bims-dicesi 2025-01-12 papers

bims-dicesi

Biomed News

on Diversification of cell signalling

Issue of 2025–01–12
33 papers selected by
Ashanika Karandawela

Small Molecule Modulators of β-arrestins.
Metabotropic GABAB Receptor Activation Induced by G Protein Coupling.
Molecular mechanisms of inverse agonism via κ-opioid receptor-G protein complexes.
Arrestin-independent internalization of the GLP-1 receptor is facilitated by a GRK, clathrin, and caveolae-dependent mechanism.
Probing non-peptide agonists binding at the human nociceptin/orphanin FQ receptor: a molecular modelling study.
Nanoscopy reveals integrin clustering reliant on kindlin-3 but not talin-1.
Structural basis of THC analog activity at the Cannabinoid 1 receptor.
The E3 ubiquitin ligase MARCH1 mediates downregulation of plasma membrane GABAB receptors under ischemic conditions by inhibiting fast receptor recycling.
Noncanonical RGS14 structural determinants control hormone-sensitive NPT2A-mediated phosphate transport.
G Protein Regulation by RGS Proteins in the Pathophysiology of Dilated Cardiomyopathy.
Correction to: Membrane progesterone receptor ε (paqr9) is necessary for chorion elevation in zebrafish.
Chemokine CXCL12 Activates CXC Receptor 4 Metastasis Signaling Through the Upregulation of a CXCL12/CXCR4/MDMX (MDM4) Axis.
Mechanistic Insights into the Adenosine A1 Receptor's Positive Allosteric Modulation for Non-Opioid Analgesics.
Investigation of serotonin-receptor interactions, stability and signal transduction pathways via molecular dynamics simulations.
Innate versus adoptive competence: the controlled distribution of signalling receptors extends the concept of competence.
Siah2 antagonism of Pard3/JamC modulates Ntn1-Dcc signaling to regulate cerebellar granule neuron germinal zone exit.
How structural interactions and receptor phosphorylation shape strigolactone signaling in rice.
Transcriptomics Unveil Canonical and Non-Canonical Heat Shock-Induced Pathways in Human Cell Lines.
Electrical signaling and coordinated behavior in the closest relative of animals.
PEAR1 Promotes Myoblast Proliferation Through Notch Signaling Pathway.
Human endometrial stem cell-derived small extracellular vesicles enhance neurite outgrowth and peripheral nerve regeneration through activating the PI3K/AKT signaling pathway.
Non-ionotropic signaling through the NMDA receptor GluN2B carboxy terminal domain drives morphological plasticity of dendritic spines and reverses fragile X phenotypes in mouse hippocampus.
The Hippo Signaling Pathway Manipulates Cellular Senescence.
Molecular Basis of Na, K-ATPase Regulation of Diseases: Hormone and FXYD2 Interactions.
The other side of the incretin story: GIPR signaling in energy homeostasis.
The Role of CXCL13 in GC-1 Cell Cycle Arrest Induced by Titanium Dioxide Nanoparticles Through JAK2/STAT3 Signaling Pathway.
Insulin signaling regulates R2 retrotransposon expression to orchestrate transgenerational rDNA copy number maintenance.
Allosteric Changes Underlie the Outside-In Transmission of Activatory Signals in the TCR.
Targeting WDR5/ATAD2 signaling by the CK2/Ikaros axis demonstrates therapeutic efficacy in T-ALL.
CD28 shapes T cell receptor signaling by regulating Lck dynamics and ZAP70 activation.
Diverging network architecture of the $\textit{C. elegans}$ connectome and signaling network.
Nuclear Factor-κB Signaling Regulates the Nociceptin Receptor but Not Nociceptin Itself.
Notch Signaling and PD-1/PD-L1 Interaction in Hepatocellular Carcinoma: Potentialities of Combined Therapies.

bioRxiv. 2024 Dec 27. pii: 2024.12.27.630464. [Epub ahead of print]

Small Molecule Modulators of β-arrestins.

Alem W Kahsai, Natalia Pakharukova, Henry Y Kwon, Kunal S Shah, Jason G Liang-Lin, Caroline T Del Real, Paul J Shim, Mason A Lee, Van A Ngo, Bowie N Shreiber, Samuel Liu, Allison M Schwalb, Emmanuel F Espinoza, Brittany N Thomas, Cal A Kunzle, Jeffrey S Smith, Jialu Wang, Jihee Kim, Xingdong Zhang, Howard A Rockman, Alex R B Thomsen, Lindsay A M Rein, Lei Shi, Seungkirl Ahn, Ali Masoudi, Robert J Lefkowitz.

β-arrestins (βarrs) are key regulators of G protein-coupled receptors (GPCRs), essential for modulating signaling pathways and physiological processes. While current pharmacological strategies target GPCR orthosteric and allosteric sites, as well as G protein transducers, comparable tools for studying βarrs are lacking. Here, we present the discovery and characterization of novel small-molecule allosteric inhibitors of βarrs through comprehensive biophysical, biochemical, pharmacological, and structural analyses. These inhibitors disrupt βarr interactions with agonist-activated GPCRs, impairing receptor internalization, desensitization, and βarr-mediated physiological functions. A cryo-EM structure of βarr1 in complex with the allosteric inhibitor Cmpd-5, complemented by molecular dynamics simulations and mutagenesis studies, reveals that Cmpd-5 binds within a cryptic cleft formed by the middle, C-, and lariat loops-a critical site for βarr activation and recruitment to GPCRs. Thus, Cmpd-5 acts as a molecular lock, hindering βarr1 activation via an allosteric mechanism. These findings introduce novel strategies and tools for probing βarr functions.
Highlights: Small molecule strategies for modulating βarr functions in both GPCR-dependent and independent contexts.Modulators disrupt βarr interaction with GPCRs, impairing their critical functions.Cryo-EM structures reveal the allosteric inhibitor Cmpd-5 binding to a cryptic pocket between the N and C domains in the central crest of βarr1, inhibiting its activation.Structural analyses, including cryo-EM, MD simulations, and mutagenesis, reveal a unique βarr1 conformation induced by Cmpd-5, shedding light on its mechanism of allosteric inhibition.

DOI: https://doi.org/10.1101/2024.12.27.630464
J Am Chem Soc. 2025 Jan 06.

Metabotropic GABAB Receptor Activation Induced by G Protein Coupling.

Moon Young Yang, Soo-Kyung Kim, William A Goddard.

G protein-coupled receptors (GPCRs) play central roles in regulating cellular responses through heterotrimeric G proteins (GP). Extensive studies have elucidated the complex cellular signaling mediated by GPCRs that accompany dynamic conformational changes upon activation. However, there has been less focus on the role of the GP on the activation process, particularly for class C GPCRs that function as obligate dimers. Herein, we report the pivotal role of GP coupling on the dynamic activation process for the metabotropic γ-aminobutyric acid receptor (GABABR) based on extensive atomistic simulations. We find that GP coupling triggers drastic conformational changes in the GABABR transmembrane domain (TMD), while an agonist alone is insufficient to shift the equilibrium state from the inactive to the active states. These conformational changes induced by GP coupling destabilize the inactive TM5/TM5 interface, shifting the equilibrium toward the activated TM6/TM6 interface. This active role of the GP in activation provides fresh insights into the activation mechanism of GABABR and perhaps other class C GPCRs. These insights should aid in the development of more potent and selective drugs.

DOI: https://doi.org/10.1021/jacs.4c14672
Nat Chem Biol. 2025 Jan 07.

Molecular mechanisms of inverse agonism via κ-opioid receptor-G protein complexes.

Aaliyah S Tyson, Saif Khan, Zenia Motiwala, Gye Won Han, Zixin Zhang, Mohsen Ranjbar, Daniel Styrpejko, Nokomis Ramos-Gonzalez, Stone Woo, Kelly Villers, Delainey Landaker, Terry Kenakin, Ryan Shenvi, Susruta Majumdar, Cornelius Gati.

Opioid receptors, a subfamily of G protein-coupled receptors (GPCRs), are key therapeutic targets. In the canonical GPCR activation model, agonist binding is required for receptor-G protein complex formation, while antagonists prevent G protein coupling. However, many GPCRs exhibit basal activity, allowing G protein association without an agonist. The pharmacological impact of agonist-free receptor-G protein complexes is poorly understood. Here we present biochemical evidence that certain κ-opioid receptor (KOR) inverse agonists can act via KOR-Gi protein complexes. To investigate this phenomenon, we determined cryo-EM structures of KOR-Gi protein complexes with three inverse agonists: JDTic, norBNI and GB18, corresponding to structures of inverse agonist-bound GPCR-G protein complexes. Remarkably, the orthosteric binding pocket resembles the G protein-free 'inactive' receptor conformation, while the receptor remains coupled to the G protein. In summary, our work challenges the canonical model of receptor antagonism and offers crucial insights into GPCR pharmacology.

DOI: https://doi.org/10.1038/s41589-024-01812-0
FEBS J. 2025 Jan 05.

Arrestin-independent internalization of the GLP-1 receptor is facilitated by a GRK, clathrin, and caveolae-dependent mechanism.

Ee Von Moo, Thor Christian Møller, Frederikke Astrid Sørensen, Asuka Inoue, Hans Bräuner-Osborne.

  The glucagon-like peptide-1 receptor (GLP-1R) plays an important role in regulating insulin secretion and reducing body weight, making it a prominent target in the treatment of type 2 diabetes and obesity. Extensive research on GLP-1R signaling has provided insights into the connection between receptor function and physiological outcomes, such as the correlation between Gs signaling and insulin secretion, yet the exact mechanisms regulating signaling remain unclear. Here, we explore the internalization pathway of GLP-1R, which is crucial for controlling insulin release and maintaining pancreatic beta-cell function. Utilizing a reliable and sensitive time-resolved fluorescence resonance energy transfer (TR-FRET) internalization assay, combined with HEK293-derived knockout cell lines, we were able to directly compare the involvement of different endocytic machinery in GLP-1R internalization. Our findings indicate that the receptor internalizes independently of arrestin and is dependent on Gs and Gi/o activation and G protein-coupled receptor kinase phosphorylation. Mechanistically, we observed that the receptor undergoes distinct clathrin- and caveolae-mediated internalization in HEK293 cells. This study also investigated the role of arrestins in GLP-1R function and regulation. These insights into key endocytic components that are involved in the GLP-1R internalization pathway could enhance the rational design of GLP-1R therapeutics for type 2 diabetes and other GLP-1R-related diseases.

Keywords:  CRISPR/cas9; GLP‐1R; GPCR; arrestins; receptor internalization

DOI:  https://doi.org/10.1111/febs.17338
RSC Med Chem. 2024 Dec 10.

Probing non-peptide agonists binding at the human nociceptin/orphanin FQ receptor: a molecular modelling study.

Matteo Gozzi, Davide Malfacini, Valentina Albanese, Salvatore Pacifico, Delia Preti, Remo Guerrini, Girolamo Calò, Antonella Ciancetta.

The N/OFQ-NOP receptor is a fascinating peptidergic system with the potential to be exploited for the development of analgesic drugs devoid of side effects associated with classical opioid signalling modulation. To date, up to four X-ray and cryo-EM structures of the NOP receptor in complex with the endogenous peptide agonist N/OFQ and three small molecule antagonists have been solved and released. Despite the available structural information, the details of selective small molecule agonist binding to the NOP receptor in the active state remain elusive. In this study, by leveraging the available structural information and using N/OFQ(1-13)-NH2 as a reference compound, we developed a computational protocol based on docking followed by short molecular dynamics (MD) simulations that can suggest small molecule agonist binding modes at the NOP receptor that are reproducible and stable over time in the solvated membrane-embedded receptor active state and in agreement with known structure-activity relationship (SAR) data.

DOI: https://doi.org/10.1039/d4md00747f
Cell Commun Signal. 2025 Jan 07. 23(1): 12

Nanoscopy reveals integrin clustering reliant on kindlin-3 but not talin-1.

Yuanyuan Wu, Ziming Cao, Wei Liu, Jason G Cahoon, Kepeng Wang, Penghua Wang, Liang Hu, Yunfeng Chen, Markus Moser, Anthony T Vella, Klaus Ley, Lai Wen, Zhichao Fan.

   BACKGROUND: Neutrophils are the most abundant leukocytes in human blood, and their recruitment is essential for innate immunity and inflammatory responses. The initial and critical step of neutrophil recruitment is their adhesion to vascular endothelium, which depends on G protein-coupled receptor (GPCR) triggered integrin inside-out signaling that induces β2 integrin activation and clustering on neutrophils. Kindlin-3 and talin-1 are essential regulators for the inside-out signaling induced β2 integrin activation. However, their contribution in the inside-out signaling induced β2 integrin clustering is unclear because conventional assays on integrin clustering are usually performed on adhered cells, where integrin-ligand binding concomitantly induces integrin outside-in signaling.
METHODS: We used flow cytometry and quantitative super-resolution stochastic optical reconstruction microscopy (STORM) to quantify β2 integrin activation and clustering, respectively, in kindlin-3 and talin-1 knockout leukocytes. We also tested whether wildtype or Pleckstrin homology (PH) domain deleted kindlin-3 can rescue the kindlin-3 knockout phenotypes.
RESULTS: GPCR-triggered inside-out signaling alone can induce β2 integrin clustering. As expected, both kindlin-3 and talin-1 knockout decreases integrin activation. Interestingly, only kindlin-3 but not talin-1 contributes to integrin clustering in the scenario of inside-out-signaling, wherein a critical role of the PH domain of kindlin-3 was highlighted.
CONCLUSIONS: Since talin was known to facilitate integrin clustering in outside-in-signaling-involved cells, our finding provides a paradigm shift by suggesting that the molecular mechanisms of integrin clustering upon inside-out signaling and outside-in signaling are different. Our data also contradict the conventional assumption that integrin activation and clustering are tightly inter-connected by showing separated regulation of the two during inside-out signaling. Our study provides a new mechanism that shows kindlin-3 regulates β2 integrin clustering and suggests that integrin clustering should be assessed independently, aside from integrin activation, when studying leukocyte adhesion in inflammatory diseases.

Keywords:  Integrin clustering; Kindlin-3; Neutrophil adhesion; STORM; Talin-1; β2 integrin

DOI:  https://doi.org/10.1186/s12964-024-02024-8
Nat Commun. 2025 Jan 08. 16(1): 486

Structural basis of THC analog activity at the Cannabinoid 1 receptor.

Thor S Thorsen, Yashraj Kulkarni, David A Sykes, Andreas Bøggild, Taner Drace, Pattarin Hompluem, Christos Iliopoulos-Tsoutsouvas, Spyros P Nikas, Henrik Daver, Alexandros Makriyannis, Poul Nissen, Michael Gajhede, Dmitry B Veprintsev, Thomas Boesen, Jette S Kastrup, David E Gloriam.

Tetrahydrocannabinol (THC) is the principal psychoactive compound derived from the cannabis plant Cannabis sativa and approved for emetic conditions, appetite stimulation and sleep apnea relief. THC's psychoactive actions are mediated primarily by the cannabinoid receptor CB1. Here, we determine the cryo-EM structure of HU210, a THC analog and widely used tool compound, bound to CB1 and its primary transducer, Gi1. We leverage this structure for docking and 1000 ns molecular dynamics simulations of THC and 10 structural analogs delineating their spatiotemporal interactions at the molecular level. Furthermore, we pharmacologically profile their recruitment of Gi and β-arrestins and reversibility of binding from an active complex. By combining detailed CB1 structural information with molecular models and signaling data we uncover the differential spatiotemporal interactions these ligands make to receptors governing potency, efficacy, bias and kinetics. This may help explain the actions of abused substances, advance fundamental receptor activation studies and design better medicines.

DOI: https://doi.org/10.1038/s41467-024-55808-4
Sci Rep. 2025 Jan 08. 15(1): 1330

The E3 ubiquitin ligase MARCH1 mediates downregulation of plasma membrane GABAB receptors under ischemic conditions by inhibiting fast receptor recycling.

Musadiq A Bhat, Mohammad Hleihil, Irene Mondéjar, Thomas Grampp, Dietmar Benke.

  GABAB receptors mediate prolonged inhibition in the brain and are important for keeping neuronal excitation and inhibition in a healthy balance. However, under excitotoxic/ischemic conditions, GABAB receptors are downregulated by dysregulated endocytic trafficking and can no longer counteract the severely enhanced excitation, eventually triggering neuronal death. Recently, we developed interfering peptides targeting protein-protein interactions involved in downregulating the receptors. Treatment with these peptides restored GABAB receptor expression after an ischemic insult and thereby inhibited neuronal overexcitation and progressive neuronal death. In this study, we searched for GABAB receptor interactions that specifically occur under ischemic conditions. We found that the E3 ubiquitin ligase MARCH1 is specifically upregulated under ischemic/excitotoxic conditions. Upregulated MARCH1 interacts with GABAB receptors and triggered downregulation of plasma membrane GABAB receptors by inhibiting fast recycling of the receptors. We developed an interfering peptide that inhibits the MARCH1/GABAB receptor interaction. Treatment of cultured neurons subjected to ischemic stress with this peptide restored receptor expression and as a consequence stopped progressive neuronal death. Thus, inhibiting the interaction of GABAB receptors with MARCH1 to restore cell surface receptor expression might be a promising strategy to prevent progressive neuronal death induced by ischemic conditions.

Keywords:  Cerebral ischemia; GABAB receptor; Interfering peptide; MARCH1; Trafficking; Ubiquitination

DOI:  https://doi.org/10.1038/s41598-025-85842-1
Biochem J. 2025 Jan 09. pii: BCJ20240122. [Epub ahead of print]

Noncanonical RGS14 structural determinants control hormone-sensitive NPT2A-mediated phosphate transport.

W Bruce Sneddon, Suneela Ramineni, G Emme Van Doorn, John R Hepler, Peter A Friedman.

  The sodium phosphate cotransporter-2A (NPT2A) mediates basal and parathyroid hormone (PTH)- and fibroblast growth factor-23 (FGF23)-regulated phosphate transport in proximal tubule cells of the kidney. Both basal and hormone-sensitive transport require sodium hydrogen exchanger regulatory factor-1 (NHERF1), a scaffold protein with tandem PDZ domains, PDZ1 and PDZ2. NPT2A binds to PDZ1. RGS14 persistently represses hormone action by binding to PDZ2. The RGS14 canonical RGS domain, Ras/Rap-binding domains, and G protein regulatory motif cannot explain its regulatory effects on hormone-sensitive phosphate transport because these actions are mediated not only by the PTH receptor, a G protein-coupled receptor (GPCR), but also by the fibroblast growth factor receptor-1, a receptor tyrosine kinase that is not governed by G protein activity. Here, we identify the structural elements of RGS14 that mutually control the action of PTH and FGF23. RGS14 truncation constructs lacking upstream sequence and the RGS domain were fully functional. Removing the linker sequence between the RGS and RBD1 domains abolished RGS14 action. Examination of the alpha-helical linker region suggested candidate serine residues that might facilitate regulatory activities. RGS14 Ser266 and Ser269 are phosphorylated in response to PTH and FGF23, and replacement of these residues by Ala eliminated the actions of RGS14 on hormone-sensitive phosphate transport. PTH stimulated the phosphorylation of a peptide construct harboring the sites of purported phosphorylation and full-length RGS14. Mutating Ser266Ala and Ser269Ala abolished phosphorylation. The results establish that RGS14 regulation of phosphate transport requires targeted phosphorylation within the linker and an intact PDZ ligand.

Keywords:  RGS14; hormone regulation; phosphorylation

DOI:  https://doi.org/10.1042/BCJ20240122
Am J Physiol Heart Circ Physiol. 2025 Jan 07.

G Protein Regulation by RGS Proteins in the Pathophysiology of Dilated Cardiomyopathy.

Yadhira E Garcia, Benita Sjögren, Patrick Osei-Owusu.

  Regulators of G protein signaling (RGS) proteins finetune signaling via heterotrimeric G proteins to maintain physiologic homeostasis in various organ systems of the human body including the brain, kidney, heart, and the vasculature. Impaired regulation of G protein signaling by RGS proteins is implicated in the pathogenesis of several human diseases including various forms of cardiomyopathy such as hypertrophic cardiomyopathy and dilated cardiomyopathy (DCM). Both genetic and non-genetic changes that impinge on G protein signaling in cardiomyocytes are implicated in the etiology of DCM, and there is accumulating evidence that such genetic and non-genetic changes affecting G protein signaling in cell types other than cardiomyocytes could serve as a DCM trigger in humans. This review discusses and highlights mammalian RGS proteins and their roles in cardiac physiology and disease, with specific focus on the current understanding of the etiology of DCM and the pathogenic roles of RGS proteins that are prominently expressed in the cardiovascular system. Growing evidence suggests that defects in G protein regulation by RGS proteins in the cardiovascular system likely contribute to cardiomyocyte structural damage and decreased contractile function that hallmark DCM. Further studies that enhance the understanding of the dynamics of G protein regulation by RGS proteins in several cell types in the myocardium and the vasculature are critical to gaining more insight into the etiology of DCM and heart failure, and to the identification of novel therapeutic targets.

Keywords:  Dilated cardiomyopathy; G protein signaling; RGS proteins; pathological mechanisms; vascular dysfunction

DOI:  https://doi.org/10.1152/ajpheart.00653.2024
Fish Physiol Biochem. 2025 Jan 07. 51(1): 5

Correction to: Membrane progesterone receptor ε (paqr9) is necessary for chorion elevation in zebrafish.

Md Razain Tanvir, Takumi Mouri, Eisei Tsutsumi, Umme Habiba Mustary, Md Almamun Farid, Md Forhad Hossain, Yuki Omori, Chihiro Yamamoto, Akiteru Maeno, Toshinobu Tokumoto.

DOI: https://doi.org/10.1007/s10695-024-01441-3
Cancers (Basel). 2024 Dec 16. pii: 4194. [Epub ahead of print]16(24):

Chemokine CXCL12 Activates CXC Receptor 4 Metastasis Signaling Through the Upregulation of a CXCL12/CXCR4/MDMX (MDM4) Axis.

Rusia Lee, Viola Ellison, Dominique Forbes, Chong Gao, Diana Katanov, Alexandra Kern, Fayola Levine, Pam Leybengrub, Olorunseun Ogunwobi, Gu Xiao, Zhaohui Feng, Jill Bargonetti.

   BACKGROUND: The metastasis-promoting G-protein-coupled receptor CXC Receptor 4 (CXCR4) is activated by the chemokine CXCL12, also known as stromal cell-derived factor 1 (SDF-1). The CXCL12/CXCR4 pathway in cancer promotes metastasis but the molecular details of how this pathway cross-talks with oncogenes are understudied. An oncogene pathway known to promote breast cancer metastasis in MDA-MB-231 xenografts is that of Mouse Double Minute 2 and 4 (MDM2 and MDM4, also known as MDMX). MDM2 and MDMX promote circulating tumor cell (CTC) formation and metastasis, and positively correlate with a high expression of CXCR4. Interestingly, this MDMX-associated upregulation of CXCR4 is only observed in cells grown in the tumor microenvironment (TME), but not in MDA-MB-231 cells grown in a tissue culture dish. This suggested a cross-talk signaling factor from the TME which was predicted to be CXCL12 and, as such, we asked if the exogenous addition of the cell non-autonomous CXCL12 ligand would recapitulate the MDMX-dependent upregulation of CXCR4.
METHODS: We used MDA-MB-231 cells and isolated CTCs, with and without MDMX knockdown, plus the exogenous addition of CXCL12 to determine if MDMX-dependent upregulation of CXCR4 could be recapitulated outside of the TME context. We added exogenous CXCL12 to the culture medium used for growth of MDA-MB-231 cells and isogenic cell lines engineered for MDM2 or MDMX depletion. We carried out immunoblotting, and quantitative RT-PCR to compare the expression of CXCR4, MDM2, MDMX, and AKT activation. We carried out Boyden chamber and wound healing assays to assess the influence of MDMX and CXCL12 on the cells' migration capacity.
RESULTS: The addition of the CXCL12 chemokine to the medium increased the CXCR4 cellular protein level and activated the PI3K/AKT signaling pathway. Surprisingly, we observed that the addition of CXCL12 mediated the upregulation of MDM2 and MDMX at the protein, but not at the mRNA, level. A reduction in MDMX, but not MDM2, diminished both the CXCL12-mediated CXCR4 and MDM2 upregulation. Moreover, a reduction in both MDM2 and MDMX hindered the ability of the added CXCL12 to promote Boyden chamber-assessed cell migration. The upregulation of MDMX by CXCL12 was mediated, at least in part, by a step upstream of the proteasome pathway because CXCL12 did not increase protein stability after cycloheximide treatment, or when the proteasome pathway was blocked.
CONCLUSIONS: These data demonstrate a positive feed-forward activation loop between the CXCL12/CXCR4 pathway and the MDM2/MDMX pathway. As such, MDMX expression in tumor cells may be upregulated in the primary tumor microenvironment by CXCL12 expression. Furthermore, CXCL12/CXCR4 metastatic signaling may be upregulated by the MDM2/MDMX axis. Our findings highlight a novel positive regulatory loop between CXCL12/CXCR4 signaling and MDMX to promote metastasis.

Keywords:  CXCR4; MDM2; MDMX; PI3K/AKT signaling; chemokine signaling; circulating tumor cells (CTCs); metastasis; triple-negative breast cancer (TNBC); tumor microenvironment (TME)

DOI:  https://doi.org/10.3390/cancers16244194
Cells. 2024 Dec 21. pii: 2121. [Epub ahead of print]13(24):

Mechanistic Insights into the Adenosine A1 Receptor's Positive Allosteric Modulation for Non-Opioid Analgesics.

Tal Weizmann, Abigail Pearce, Peter Griffin, Achille Schild, Maren Flaßhoff, Philipp Grossenbacher, Martin Lochner, Christopher A Reynolds, Graham Ladds, Giuseppe Deganutti.

  The adenosine A1 receptor (A1R) is a promising target for pain treatment. However, the development of therapeutic agonists is hampered by adverse effects, mainly including sedation, bradycardia, hypotension, or respiratory depression. Recently discovered molecules able to overcome this impediment are the positive allosteric modulator MIPS521 and the A1R-selective agonist BnOCPA, which are both potent and powerful analgesics with fewer side effects. While BnOCPA directly activates the A1R from the canonical orthosteric site, MIPS521 binds to an allosteric site, acting in concert with orthosteric adenosine and tuning its pharmacology. Given their overlapping profile in pain models but distinct mechanisms of action, we combined pharmacology and microsecond molecular dynamics simulations to address MIPS521 and BnOCPA activity and their reciprocal influence when bound to the A1R. We show that MIPS521 changes adenosine and BnOCPA G protein selectivity in opposite ways and propose a structural model where TM7 dynamics are differently affected and involved in the G protein preferences of adenosine and BnOCPA.

Keywords:  BnOCPA; GPCRs; MIPS521; adenosine A1 receptor; non-opioid analgesia

DOI:  https://doi.org/10.3390/cells13242121
Biophys Chem. 2024 Dec 27. pii: S0301-4622(24)00215-1. [Epub ahead of print]318 107386

Investigation of serotonin-receptor interactions, stability and signal transduction pathways via molecular dynamics simulations.

Arunima Verma, Padmabati Mondal.

  Serotonin-receptor binding plays a key role in several neurological and biological processes, including mood, sleep, hunger, cognition, learning, and memory. In this article, we performed molecular dynamics simulation to examine the key residues that play an essential role in the binding of serotonin to the G-protein-coupled 5-HT1B receptor (5HT1BR) via electrostatic interactions. Key residues for electrostatic interactions were identified via bond distance analysis and frustration analysis methods. An end-point free energy calculation method determines the stability of the 5-HT1BR due to serotonin binding. The single-point mutation of the polar/charged amino acid residues (Asp129, Thr134) on the binding sites and the calculation of binding free energy validate the quantitative contribution of these residues to the stability of the serotonin-receptor complex. The principal component analysis reflects that the serotonin-bound 5-HT1BR is more stabilized than the apo-receptor regarding dynamical changes. The difference dynamic cross-correlations map shows the correlation between the transmembranes and mini-Go, which indicates that the signal transduction happens between mini-Go and the receptor. Allosteric pathway analysis reveals the key nodes and key pathways for signal transduction in 5-HT1BR. These results provide useful insights into the study of signal transduction pathways and mutagenesis to regulate the binding and functionality of the complex. The developed protocols can be applied to study local non-covalent interactions and long-range allosteric communications in any protein-ligand system for computer-aided drug design.

Keywords:  Allosteric pathway; Binding free energy; Electrostatic interactions; Molecular dynamics simulation; Serotonin-receptor binding; Signal transduction

DOI:  https://doi.org/10.1016/j.bpc.2024.107386
Trends Cell Biol. 2025 Jan 06. pii: S0962-8924(24)00258-7. [Epub ahead of print]

Innate versus adoptive competence: the controlled distribution of signalling receptors extends the concept of competence.

Jessica L Bamsey, Lucy Brunt, Steffen Scholpp.

  Cellular communication through the dissemination of signal molecules is vital for tissue organisation and homeostasis. The mechanisms of signal spreading can include binding-protein-assisted transport, long membrane protrusions known as cytonemes, and exovesicles. Recent research indicates that cytonemes and exovesicles can not only transport ligands but also facilitate the regulated distribution of receptors, thereby enabling signal transduction in cells lacking endogenous receptors. This mechanism allows non-responsive cells to temporarily acquire the ability to respond to specific ligands. This review explores our understanding of ligand and receptor dispersal, offering fresh insights into the fundamental concept of cellular competence. Notably, these findings may have significant implications for diseases and their associated therapeutic targets, highlighting the urgency and importance of this research area.

Keywords:  Wnt; competence; cytonemes; exovesicles; morphogen; receptor

DOI:  https://doi.org/10.1016/j.tcb.2024.12.005
Nat Commun. 2025 Jan 07. 16(1): 355

Siah2 antagonism of Pard3/JamC modulates Ntn1-Dcc signaling to regulate cerebellar granule neuron germinal zone exit.

Christophe Laumonnerie, Maleelo Shamambo, Daniel R Stabley, Tommy L Lewis, Niraj Trivedi, Danielle Howell, David J Solecki.

Exiting a germinal zone (GZ) initiates a cascade of events that promote neuronal maturation and circuit assembly. Developing neurons and their progenitors must interpret various niche signals-such as morphogens, guidance molecules, extracellular matrix components, and adhesive cues-to navigate this region. How differentiating neurons in mouse brains integrate and adapt to multiple cell-extrinsic niche cues with their cell-intrinsic machinery in exiting a GZ is unknown. We establish cooperation between cell polarity-regulated adhesion and Netrin-1 signaling comprises a coincidence detection circuit repelling maturing neurons from their GZ. In this circuit, the Partitioning defective 3 (Pard3) polarity protein and Junctional adhesion molecule-C (JamC) adhesion molecule promote, while the Seven in absentia 2 (Siah2) ubiquitin ligase inhibits, Deleted in colorectal cancer (Dcc) receptor surface recruitment to gate differentiation linked repulsion to GZ Netrin-1. These results demonstrate cell polarity as a central integrator of adhesive- and guidance cues cooperating to spur GZ exit.

DOI: https://doi.org/10.1038/s41467-024-55400-w
Dev Cell. 2025 Jan 06. pii: S1534-5807(24)00768-8. [Epub ahead of print]60(1): 5-7

How structural interactions and receptor phosphorylation shape strigolactone signaling in rice.

Kawthar F Alashoor, Salim Al-Babili.

The phytohormone strigolactone (SL) regulates various developmental processes and plant adaptation to nutrient availability, which in turn regulates strigolactone biosynthesis. In the recent issue of Cell, Hu et al.1 advance the understanding of the interaction of the SL receptor complex and reveal exciting insights into the nitrogen-dependent regulation of SL signaling and SL-dependent tillering in rice.

DOI: https://doi.org/10.1016/j.devcel.2024.12.029
bioRxiv. 2024 Dec 23. pii: 2024.12.22.629972. [Epub ahead of print]

Transcriptomics Unveil Canonical and Non-Canonical Heat Shock-Induced Pathways in Human Cell Lines.

Andrew Reinschmidt, Luis Solano, Yonny Chavez, William Drew Hulsy, Nikolas Nikolaidis.

The cellular stress response (CSR) is a conserved mechanism that protects cells from environmental and physiological stressors. The heat shock response (HSR), a critical component of the CSR, utilizes molecular chaperones to mitigate proteotoxic stress caused by elevated temperatures. We hypothesized that while the canonical HSR pathways are conserved across cell types, specific cell lines may exhibit unique transcriptional responses to heat shock. To test this, we compared the transcriptomic responses of HEK293, HepG2, and HeLa cells under control conditions immediately following heat shock and after an 8-hour recovery period. RNA sequencing revealed conserved activation of canonical HSR pathways, including the unfolded protein response, alongside enrichment of the non-canonical "Receptor Ligand Activity" pathway across all cell lines. Cell line-specific variations were also observed, with HepG2 cells displaying more uniquely expressed genes and elevated expression levels (fold changes) of shared genes under stress conditions. Validation by qPCR confirmed the activation of key genes within the "Receptor Ligand Activity" pathway across time points. These findings provide insights into conserved and context-specific aspects of the HSR, contributing to a more comprehensive understanding of stress response mechanisms across mammalian cells.

DOI: https://doi.org/10.1101/2024.12.22.629972
Sci Adv. 2025 Jan 10. 11(2): eadr7434

Electrical signaling and coordinated behavior in the closest relative of animals.

Jeffrey Colgren, Pawel Burkhardt.

The transition from simple to complex multicellularity involves division of labor and specialization of cell types. In animals, complex sensory-motor systems are primarily built around specialized cells of muscles and neurons, though the evolutionary origins of these and their integration remain unclear. Here, to investigate sensory-behavior coupling in the closest relatives of animals, we established a line of the choanoflagellate, Salpingoeca rosetta, which stably expresses the calcium indicator RGECO1. Using this, we identify a previously unknown cellular behavior associated with electrical signaling, in which ciliary arrest is coupled with apical-basal contraction of the cell. This behavior and the associated calcium transients are synchronized in the multicellular state and result in coordinated ciliary arrest and colony-wide contraction, suggesting that information is spread among the cells. Our work reveals fundamental insights into how choanoflagellates sense and respond to their environment and enhances our understanding of the integration of cellular and organism-wide behavior in the closest protistan relatives of animals.

DOI: https://doi.org/10.1126/sciadv.adr7434
Biology (Basel). 2024 Dec 19. pii: 1063. [Epub ahead of print]13(12):

PEAR1 Promotes Myoblast Proliferation Through Notch Signaling Pathway.

Yahao Zhao, Lu Zhang, Ruotong Hao, Shuang Li, Shufeng Li, Shuai Shi, Huili Tong, Bingchen Liu.

  PEAR1, also known as platelet endothelial aggregation receptor 1, is known to play a crucial role in the migration and differentiation of muscle satellite cells (MuSCs). However, its specific effects on skeletal muscle development and regeneration require further exploration. In this study, the expression of PEAR1; the proliferation marker proteins of Pax7, CCNB1, and PCNA; and the key molecules of N1-ICD, N2-ICD, and Hes1 were all increased gradually during the process of C2C12 cell proliferation. Furthermore, Western blotting and EdU results showed that when PEAR1 was over-expressed or inhibited, the proliferation status of C2C12 cell was increased or reduced respectively. This implied that PEAR1 could regulate myoblast proliferation and might be relate to Notch cell signaling pathway. A subsequent immunoprecipitation experiment result showed that the interaction between PEAR1 and Notch1 or Notch2, respectively. Then Western blotting and EdU results showed that the proliferation of C2C12 cell was inhibited under the treatment of Notch signaling pathway inhibitor RIN1. Meanwhile, the proliferation capacity of C2C12 cell could not be improved by treatment with RIN1 even though PEAR1 was over-expressed. These results showed that PEAR1 may regulated C2C12 cell proliferation though Notch signaling pathway. Additionally, a mouse model of muscle injury repair injected with bupivacaine hydrochloride was established in this study. Immunohistochemistry results exhibited that PEAR1 may regulate skeletal muscle post-injury regeneration relevant to Notch1 and Notch2 in different patterns. These findings provide valuable insights into the potential involvement of PEAR1 in skeletal muscle development and post-injury regeneration.

Keywords:  Notch signaling pathway; PEAR1; myoblast proliferation; skeletal muscle regeneration

DOI:  https://doi.org/10.3390/biology13121063
J Transl Med. 2025 Jan 03. 23(1): 6

Human endometrial stem cell-derived small extracellular vesicles enhance neurite outgrowth and peripheral nerve regeneration through activating the PI3K/AKT signaling pathway.

Mojdeh Salehi Namini, Nima Beheshtizadeh, Somayeh Ebrahimi-Barough, Jafar Ai.

  Nowadays, extracellular vesicles (EVs) such as exosomes participate in cell-cell communication and gain attention as a new approach for cell-free therapies. Recently, various studies have demonstrated the therapeutic ability of exosomes, while the biological effect of human endometrial stem cell (hEnSC)-derived small EVs such as exosomes is still unclear. Herein, we obtained small EVs from hEnSC and indicated that these small EVs activate the vital cell signaling pathway and progress neurite outgrowth in PC-12 cell lines. For this purpose, hEnSC-derived small EVs were extracted by ultracentrifuge and characterized by DLS, SEM, TEM, and western blot. Also, dil-staining of hEnSC-derived small EVs was done to determine the penetration of hEnSC-derived small EVs into PC12 cells. The MTT assay, scratch assay, and western blot assay were applied to PC12 cells that were exposed to different concentrations of small EVs (0, 50, 100, and 150 µg/ml). Our results demonstrated that small EVs significantly increased neurite outgrowth, proliferation, and migration in PC12 cells in a dose-dependent manner. Moreover, the analysis of western blots showed increased expression of the PI3k/AKT signaling pathway in PC12 cells exposed to hEnSC-derived small EVs in a dose-dependent manner. Also, the results of this study indicated that hEnSC-derived small EVs can enhance cell proliferation and migration and promote neural outgrowth by activating the PI3k/AKT signaling pathway. Accordingly, hEnSC-derived small EVs became an effective strategy for cell-free therapies. Altogether, these positive effects make hEnSC-derived small EVs a new efficient approach in regenerative medicine, especially for the cure of neural injury.

Keywords:  Exosomes; Human endometrial stem cells; Nerve tissue regeneration; PC12 cells; PI3k/AKT signaling pathway; Small EVs

DOI:  https://doi.org/10.1186/s12967-024-06048-z
bioRxiv. 2024 Dec 23. pii: 2024.12.15.628559. [Epub ahead of print]

Non-ionotropic signaling through the NMDA receptor GluN2B carboxy terminal domain drives morphological plasticity of dendritic spines and reverses fragile X phenotypes in mouse hippocampus.

Stephanie A Barnes, Aurore Thomazeau, Peter S B Finnie, Maxwell J Heinrich, Arnold J Heynen, Noburu H Komiyama, Seth G N Grant, Frank S Menniti, Emily K Osterweil, Mark F Bear.

It is well known that activation of NMDA receptors can trigger long-term synaptic depression (LTD) and that a morphological correlate of this functional plasticity is spine retraction and elimination. Recent studies have led to the surprising conclusion that NMDA-induced spine shrinkage proceeds independently of ion flux and requires the initiation of de novo protein synthesis, highlighting an unappreciated contribution of mRNA translation to non-ionotropic NMDAR signaling. Here we used NMDA-induced spine shrinkage in slices of mouse hippocampus as a readout to investigate this novel modality of synaptic transmission. By using selective pharmacological and genetic tools, we find that structural plasticity is dependent on the ligand binding domain (LBD) of GluN2B-containing NMDA receptors and that metabotropic signaling occurs via the GluN2B carboxyterminal domain (CTD). Disruption of signaling by replacing the GluN2B CTD with the GluN2A CTD leads to increased spine density, dysregulated basal protein synthesis, and epileptiform activity in area CA3 reminiscent of phenotypes observed in the Fmr1 -/y model of fragile X syndrome. By crossing the Fmr1 -/y mice with animals in which the GluN2A CTD has been replaced with the GluN2B CTD, we observe a correction of these core fragile X phenotypes. These findings suggest that non-ionotropic NMDAR signaling through GluN2B may represent a novel therapeutic target for treatment of fragile X and related causes of intellectual disability and autism.

DOI: https://doi.org/10.1101/2024.12.15.628559
Cells. 2024 Dec 26. pii: 13. [Epub ahead of print]14(1):

The Hippo Signaling Pathway Manipulates Cellular Senescence.

Chiharu Miyajima, Mai Nagasaka, Hiromasa Aoki, Kohki Toriuchi, Shogo Yamanaka, Sakura Hashiguchi, Daisuke Morishita, Mineyoshi Aoyama, Hidetoshi Hayashi, Yasumichi Inoue.

  The Hippo pathway, a kinase cascade, coordinates with many intracellular signals and mediates the regulation of the activities of various downstream transcription factors and their coactivators to maintain homeostasis. Therefore, the aberrant activation of the Hippo pathway and its associated molecules imposes significant stress on tissues and cells, leading to cancer, immune disorders, and a number of diseases. Cellular senescence, the mechanism by which cells counteract stress, prevents cells from unnecessary damage and leads to sustained cell cycle arrest. It acts as a powerful defense mechanism against normal organ development and aging-related diseases. On the other hand, the accumulation of senescent cells without their proper removal contributes to the development or worsening of cancer and age-related diseases. A correlation was recently reported between the Hippo pathway and cellular senescence, which preserves tissue homeostasis. This review is the first to describe the close relationship between aging and the Hippo pathway, and provides insights into the mechanisms of aging and the development of age-related diseases. In addition, it describes advanced findings that may lead to the development of tissue regeneration therapies and drugs targeting rejuvenation.

Keywords:  Hippo pathway; cancer; cellular senescence

DOI:  https://doi.org/10.3390/cells14010013
Int J Mol Sci. 2024 Dec 13. pii: 13398. [Epub ahead of print]25(24):

Molecular Basis of Na, K-ATPase Regulation of Diseases: Hormone and FXYD2 Interactions.

Bárbara Martins Cordeiro, Carlos Frederico Leite Fontes, José Roberto Meyer-Fernandes.

  The Na, K-ATPase generates an asymmetric ion gradient that supports multiple cellular functions, including the control of cellular volume, neuronal excitability, secondary ionic transport, and the movement of molecules like amino acids and glucose. The intracellular and extracellular levels of Na+ and K+ ions are the classical local regulators of the enzyme's activity. Additionally, the regulation of Na, K-ATPase is a complex process that occurs at multiple levels, encompassing its total cellular content, subcellular distribution, and intrinsic activity. In this context, the enzyme serves as a regulatory target for hormones, either through direct actions or via signaling cascades triggered by hormone receptors. Notably, FXYDs small transmembrane proteins regulators of Na, K-ATPase serve as intermediaries linking hormonal signaling to enzymatic regulation at various levels. Specifically, members of the FXYD family, particularly FXYD1 and FXYD2, are that undergo phosphorylation by kinases activated through hormone receptor signaling, which subsequently influences their modulation of Na, K-ATPase activity. This review describes the effects of FXYD2, cardiotonic steroid signaling, and hormones such as angiotensin II, dopamine, insulin, and catecholamines on the regulation of Na, K-ATPase. Furthermore, this review highlights the implications of Na, K-ATPase in diseases such as hypertension, renal hypomagnesemia, and cancer.

Keywords:  FXYD2; Na, K–ATPase; cancer; diseases; hormonal regulation; hypertension; ion transport; protein kinases; receptors; renal hypomagnesemia; signal transduction

DOI:  https://doi.org/10.3390/ijms252413398
Cell Metab. 2025 Jan 07. pii: S1550-4131(24)00485-6. [Epub ahead of print]37(1): 1-3

The other side of the incretin story: GIPR signaling in energy homeostasis.

Susana C B R Nakandakari, Andin E Fosam, Rachel J Perry.

Incretin receptor agonists have been effective in combatting obesity and diabetes. While the body of knowledge regarding the signaling mechanisms of glucagon-like peptide 1 (GLP-1) receptor agonists is ever-growing, glucose-dependent insulinotropic polypeptide receptor (GIPR) agonists are less understood. The previewed papers offer insight into the impact of adipose GIPR on energy and weight homeostasis.

DOI: https://doi.org/10.1016/j.cmet.2024.12.003
J Appl Toxicol. 2025 Jan 07.

The Role of CXCL13 in GC-1 Cell Cycle Arrest Induced by Titanium Dioxide Nanoparticles Through JAK2/STAT3 Signaling Pathway.

Yuzhu Lei, Ruoyun Dong, Chenhao Sun, Yunhua Hu, Yizhong Yan, Guanling Song, Yan Wang.

  Titanium dioxide nanoparticles (TiO2 NPs) can induce the cell cycle arrest in spermatogonia, and the JAK2/STAT3 signaling pathway plays a pivotal role in cell cycle progression, but the specific upstream regulatory mechanisms are not completely clarified. The purpose of this study was to investigate whether CXCL13 regulated the JAK2/STAT3 signaling pathway to participate in cell cycle arrest after mouse spermatogonia cell line (GC-1) exposure to TiO2 NPs. The GC-1 cells were treated with TiO2 NPs at different concentrations (0, 10, 20, 30, and 40 μg/mL) for 24 h to detect cell viability, cell cycle distribution, CXCL13 protein, JAK2/STAT3 pathway-related proteins, and cell cycle-related proteins. The CXCL13 recombinant protein was used to verify the role of CXCL13 in cell cycle and JAK2/STAT3 signaling pathway. TiO2 NPs inhibited cell viability; regulated cell cycle-related proteins including remarkably decreased Cyclin D1, CDK4, Cyclin E1, and CDK2 as well as increased p21; and induced cell cycle arrest at the G0/G1 phase. TiO2 NPs inhibited the levels of CXCL13 protein and weakened the activation of the JAK2/STAT3 signaling pathway by reducing the levels of p-JAK2/JAK2 and p-STAT3/STAT3 proteins. Furthermore, CXCL13 mitigated the suppression of the JAK2/STAT3 signaling pathway and the G0/G1 cell cycle arrest caused by TiO2 NPs. Taken together, TiO2 NPs downregulated the expression of CXCL13 to inhibit the activation of downstream JAK2/STAT3 signaling pathway, eventually inducing cell cycle arrest at the G0/G1 phase. These results provide a novel insight for complemented understanding of the mechanisms of TiO2 NPs-induced cell cycle arrest in GC-1 cells.

Keywords:  CXCL13; GC‐1 cells; JAK2/STAT3 signaling pathway; cell cycle arrest; titanium dioxide nanoparticles

DOI:  https://doi.org/10.1002/jat.4747
Nat Commun. 2025 Jan 04. 16(1): 399

Insulin signaling regulates R2 retrotransposon expression to orchestrate transgenerational rDNA copy number maintenance.

Jonathan O Nelson, Alyssa Slicko, Amelie A Raz, Yukiko M Yamashita.

Preserving a large number of essential yet highly unstable ribosomal DNA (rDNA) repeats is critical for the germline to perpetuate the genome through generations. Spontaneous rDNA loss must be countered by rDNA copy number (CN) expansion. Germline rDNA CN expansion is best understood in Drosophila melanogaster, which relies on unequal sister chromatid exchange (USCE) initiated by DNA breaks at rDNA. The rDNA-specific retrotransposon R2 responsible for USCE-inducing DNA breaks is typically expressed only when rDNA CN is low to minimize the danger of DNA breaks; however, the underlying mechanism of R2 regulation remains unclear. Here we identify the insulin receptor (InR) as a major repressor of R2 expression, limiting unnecessary R2 activity. Through single-cell RNA sequencing, we find that male germline stem cells (GSCs), the major cell type that undergoes rDNA CN expansion, have reduced InR expression when rDNA CN is low. Reduced InR activity in turn leads to R2 expression and CN expansion. We further find that dietary manipulation alters R2 expression and rDNA CN expansion activity. This work reveals that the insulin pathway integrates rDNA CN surveying with environmental sensing, revealing a potential mechanism by which diet exerts heritable changes to genomic content.

DOI: https://doi.org/10.1038/s41467-024-55725-6
Immunol Rev. 2025 Jan;329(1): e13438

Allosteric Changes Underlie the Outside-In Transmission of Activatory Signals in the TCR.

Balbino Alarcon, Wolfgang W Schamel.

  Rather than being contained in a single polypeptide, and unlike receptor tyrosine kinases, the T cell receptor (TCR) divides its signaling functions among its subunits: TCRα/β bind the extracellular ligand, an antigenic peptide-MHC complex (pMHC), and the CD3 subunits (CD3γ, CD3δ, CD3ε, and CD3ζ) transmit this information to the cytoplasm. How information about the quality of pMHC binding outside is transmitted to the cytoplasm remains a matter of debate. In this review, we compile data generated using a wide variety of experimental systems indicating that TCR engagement by an appropriate pMHC triggers allosteric changes transmitted from the ligand-binding loops in the TCRα and TCRβ subunits to the cytoplasmic tails of the CD3 subunits. We summarize how pMHC and stimulatory antibody binding to TCR ectodomains induces the exposure of a polyproline sequence in the CD3ε cytoplasmic tail for binding to the Nck adapter, the exposure of the RK motif in CD3ε for recruiting the Lck tyrosine kinase, and the induced exposure and phosphorylation of tyrosine residues in all the CD3 cytoplasmic tails. We also review the yet incipient data that help elucidate the structural basis of the Active and Resting conformations of the TCR.

Keywords:  CD3; PRS; TCR; allostery; conformation; triggering

DOI:  https://doi.org/10.1111/imr.13438
Blood. 2024 Dec 27. pii: blood.2024024130. [Epub ahead of print]

Targeting WDR5/ATAD2 signaling by the CK2/Ikaros axis demonstrates therapeutic efficacy in T-ALL.

Qi Han, Yan Gu, Huimin Xiang, Linyao Zhang, Yan Wang, Chan Yang, Jun Li, Chelsea Steiner, Rosa Lapalombella, Jennifer A Woyach, Yiping Yang, Sinisa Dovat, Chunhua Song, Zheng Ge.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy with a poor prognosis and limited options for targeted therapies. Identifying new molecular targets to develop novel therapeutic strategies is the pressing immediate issue in T-ALL. Here, we observed high expression of WD Repeat-Containing Protein 5 (WDR5) in T-ALL; with in vitro and in vivo models we demonstrated the oncogenic role of WDR5 in T-ALL by activating cell cycle signaling through its new downstream effector, ATPase family AAA domain-containing 2 (ATAD2). Moreover, IKAROS' function is often impaired by genetic alteration as well as casein kinase II (CK2) which is overexpressed in T-ALL. We found IKAROS directly regulates WDR5 transcription; CK2 inhibitor, CX-4945 strongly suppresses WDR5 expression by restoring IKAROS function. Lastly, combining CX-4945 with WDR5 inhibitor demonstrates synergistic efficacy in the patient-derived xenograft mouse models. In conclusion, our results demonstrated that WDR5/ATAD2 is a new oncogenic signaling pathway in T-ALL, and simultaneous targeting of WRD5 and CK2/IKAROS has synergistic anti-leukemic efficacy and represents a promising potential strategy for T-ALL therapy.

DOI: https://doi.org/10.1182/blood.2024024130
Front Immunol. 2024 ;15 1503018

CD28 shapes T cell receptor signaling by regulating Lck dynamics and ZAP70 activation.

Kumarkrishna Raychaudhuri, Rohita Rangu, Alison Ma, Neriah Alvinez, Andy D Tran, Sandeep Pallikkuth, Katherine M McIntire, Joseph A Garvey, Jason Yi, Lawrence E Samelson.

   Introduction: T cell activation requires T cell receptor (TCR) engagement by its specific ligand. This interaction initiates a series of proximal events including tyrosine phosphorylation of the CD3 and TCRζ chains, recruitment, and activation of the protein tyrosine kinases Lck and ZAP70, followed by recruitment of adapter and signaling proteins. CD28 co-stimulation is also required to generate a functional immune response. Currently we lack a full understanding of the molecular mechanism of CD28 activation.
Methods: We employed TIRF microscopy to establish detailed spatial and kinetic relationships among these molecules in live Jurkat and murine primary T cells. We used anti-TCR (CD3) antibodies to trigger formation of TCR microclusters (MC), which are submicron-sized basic signaling units formed during T cell activation. Using this model, we aimed to delineate how the CD28 co-stimulatory signal alters the kinetics and molecular stoichiometry of TCR proximal signaling events, and how these effects could affect the immune response.
Results: Our results show that CD28 co-stimulation specifically accelerated recruitment of ZAP70 to the TCRζ chain in MCs and increased ZAP70 activation. CD28-mediated acceleration of ZAP70 recruitment was driven by enhanced Lck recruitment to the MCs. A greater spatial separation between active and inactive species of Lck was also observed in the MCs as a consequence of CD28 co-stimulation.
Conclusion: These results suggest that CD28 co- stimulation may lower the TCR activation threshold by enhancing the activated form of Lck in the TCR MCs.

Keywords:  CD28 co-stimulation; Lck; T cell signaling; ZAP70; and kinetic proof-reading; microcluster

DOI:  https://doi.org/10.3389/fimmu.2024.1503018
ArXiv. 2024 Dec 19. pii: arXiv:2412.14498v1. [Epub ahead of print]

Diverging network architecture of the $\textit{C. elegans}$ connectome and signaling network.

Sophie Dvali, Caio Seguin, Richard Betzel, Andrew M Leifer.

The connectome describes the complete set of synaptic contacts through which neurons communicate. While the architecture of the $\textit{C. elegans}$ connectome has been extensively characterized, much less is known about the organization of causal signaling networks arising from functional interactions between neurons. Understanding how effective communication pathways relate to or diverge from the underlying structure is a central question in neuroscience. Here, we analyze the modular architecture of the $\textit{C. elegans}$ signal propagation network, measured via calcium imaging and optogenetics, and compare it to the underlying anatomical wiring measured by electron microscopy. Compared to the connectome, we find that signaling modules are not aligned with the modular boundaries of the anatomical network, highlighting an instance where function deviates from structure. An exception to this is the pharynx which is delineated into a separate community in both anatomy and signaling. We analyze the cellular compositions of the signaling architecture and find that its modules are enriched for specific cell types and functions, suggesting that the network modules are neurobiologically relevant. Lastly, we identify a "rich club" of hub neurons in the signaling network. The membership of the signaling rich club differs from the rich club detected in the anatomical network, challenging the view that structural hubs occupy positions of influence in functional (signaling) networks. Our results provide new insight into the interplay between brain structure, in the form of a complete synaptic-level connectome, and brain function, in the form of a system-wide causal signal propagation atlas.
Cells. 2024 Dec 20. pii: 2111. [Epub ahead of print]13(24):

Nuclear Factor-κB Signaling Regulates the Nociceptin Receptor but Not Nociceptin Itself.

Lan Zhang, Ulrike M Stamer, Robin Moolan-Vadackumchery, Frank Stüber.

  The nociceptin receptor (NOP) and nociceptin are involved in the pathways of pain and inflammation. The potent role of nuclear factor-κB (NFκB) in the modulation of tumor necrosis factor-α (TNF-α) and interleukin (IL)-1β on the nociceptin system in human THP-1 cells under inflammatory conditions were investigated. Cells were stimulated without/with phorbol-myristate-acetate (PMA), TNF-α, IL-1β, or PMA combined with individual cytokines. To examine NFκB's contribution to the regulation of the nociceptin system, PMA-stimulated cells were treated with NFκB inhibitor BAY 11-7082, JSH-23, or anacardic acid before culturing with TNF-α or IL-1β. NOP and prepronociceptin (ppNOC) mRNA were quantified by RT-qPCR; cell membrane NOP and intracellular nociceptin protein levels were measured by flow cytometry. Phosphorylation and localization of NFκB/p65 were determined using ImageStream. PMA + TNF-α decreased NOP mRNA compared to stimulation with PMA alone, while PMA + IL-1β did not. BAY 11-7082 and JSH-23 reversed the repression of NOP by PMA + TNF-α. TNF-α and IL-1β attenuated PMA's upregulating effects on ppNOC. None of the inhibitors preserved the upregulation of ppNOC in PMA + TNF-α and PMA + IL-1β cultures. TNF-α strongly mediated the nuclear translocation of NFκB/p65 in PMA-treated cells, while IL-1β did not. Proinflammatory cytokines suppressed NOP and ppNOC mRNA in PMA-induced human THP-1 cells. NFκB signaling seems to be an important regulator controlling the transcription of NOP. These findings suggest that the nociceptin system may play an anti-inflammatory role during immune responses.

Keywords:  NFκB; cell cultures; cytokines; nociceptin; nociceptin receptor; signal transduction

DOI:  https://doi.org/10.3390/cells13242111
Biomolecules. 2024 Dec 11. pii: 1581. [Epub ahead of print]14(12):

Notch Signaling and PD-1/PD-L1 Interaction in Hepatocellular Carcinoma: Potentialities of Combined Therapies.

Annapaola Montagner, Andrea Arleo, Fabrizia Suzzi, Antonino B D'Assoro, Fabio Piscaglia, Laura Gramantieri, Catia Giovannini.

  Immunotherapy has shown significant improvement in the survival of patients with hepatocellular carcinoma (HCC) compared to TKIs as first-line treatment. Unfortunately, approximately 30% of HCC exhibits intrinsic resistance to ICIs, making new therapeutic combinations urgently needed. The dysregulation of the Notch signaling pathway observed in HCC can affect immune cell response, reducing the efficacy of cancer immunotherapy. Here, we provide an overview of how Notch signaling regulates immune responses and present the therapeutic rationale for combining Notch signaling inhibition with ICIs to improve HCC treatment. Moreover, we propose using exosomes as non-invasive tools to assess Notch signaling activation in hepatic cancer cells, enabling accurate stratification of patients who can benefit from combined strategies.

Keywords:  Notch; PD-1; PD-L1; combination therapy; hepatocellular carcinoma (HCC); immunotherapy

DOI:  https://doi.org/10.3390/biom14121581