bims-toxgon 2023-11-26 papers

bims-toxgon

Biomed News

on Toxoplasma gondii metabolism

Issue of 2023‒11‒26
nineteen papers selected by
Lakesh Kumar, BITS Pilani

iTRAQ-Based Phosphoproteomic Analysis Exposes Molecular Changes in the Small Intestinal Epithelia of Cats after Toxoplasma gondii Infection.
Boosting Mouse Defense against Lethal Toxoplasma gondii Infection with Full-Length and Soluble SAG1 Recombinant Protein.
Structural basis of Irgb6 inactivation by Toxoplasma gondii through the phosphorylation of switch I.
Analysis of codon usage bias of thioredoxin in apicomplexan protozoa.
Chronic Toxoplasma infection affects gene expression of drug-metabolizing enzymes in mouse liver.
Human trophoblast stem cells can be used to model placental susceptibility to Toxoplasma gondii and highlight the critical importance of the trophoblast cell surface in pathogen resistance.
Protein kinase PfPK2 mediated signalling is critical for host erythrocyte invasion by malaria parasite.
Toxoplasma gondii infection of the central nervous system and suicide: A case-control study of decedents.
Protective effect of arctiin against Toxoplasma gondii HSP70-induced allergic acute liver injury by disrupting the TLR4-mediated activation of cytosolic phospholipase A2 and platelet-activating factor.
5-((3-Amidobenzyl)oxy)nicotinamides as SIRT2 Inhibitors: A Study of Constrained Analogs.
Implications of Flagellar Attachment Zone Proteins TcGP72 and TcFLA-1BP in Morphology, Proliferation, and Intracellular Dynamics in Trypanosoma cruzi.
The Role of Sirtuin-1 (SIRT1) in the Physiology and Pathophysiology of the Human Placenta.
Characterizing Lysine Acetylation of Glucokinase.
Changes in the Proliferation of the Neural Progenitor Cells of Adult Mice Chronically Infected with Toxoplasma gondii.
Targeting Histone Deacetylases 6 in Dual-Target Therapy of Cancer.
The role of histone acetylation in transcriptional regulation and seed development.
Crystal Structures Reveal Hidden Domain Mechanics in Protein Kinase A (PKA).
ULK1 seen at the single-molecule level during autophagy initiation.
Sirtuins in macrophage immune metabolism: A novel target for cardiovascular disorders.

Animals (Basel). 2023 Nov 16. pii: 3537. [Epub ahead of print]13(22):

iTRAQ-Based Phosphoproteomic Analysis Exposes Molecular Changes in the Small Intestinal Epithelia of Cats after Toxoplasma gondii Infection.

Bintao Zhai, Yu-Meng Meng, Shi-Chen Xie, Jun-Jie Peng, Yang Liu, Yanhua Qiu, Lu Wang, Jiyu Zhang, Jun-Jun He.

  Toxoplasma gondii, an obligate intracellular parasite, has the ability to invade and proliferate within most nucleated cells. The invasion and destruction of host cells by T. gondii lead to significant changes in the cellular signal transduction network. One important post-translational modification (PTM) of proteins is phosphorylation/dephosphorylation, which plays a crucial role in cell signal transmission. In this study, we aimed to investigate how T. gondii regulates signal transduction in definitive host cells. We employed titanium dioxide (TiO2) affinity chromatography to enrich phosphopeptides in the small intestinal epithelia of cats at 10 days post-infection with the T. gondii Prugniuad (Pru) strain and quantified them using iTRAQ technology. A total of 4998 phosphopeptides, 3497 phosphorylation sites, and 1805 phosphoproteins were identified. Among the 705 differentially expressed phosphoproteins (DEPs), 68 were down-regulated and 637 were up-regulated. The bioinformatics analysis revealed that the DE phosphoproteins were involved in various cellular processes, including actin cytoskeleton reorganization, cell necroptosis, and MHC immune processes. Our findings confirm that T. gondii infection leads to extensive changes in the phosphorylation of proteins in the cat intestinal epithelial cells. The results of this study provide a theoretical foundation for understanding the interaction between T. gondii and its definitive host.

Keywords:  Toxoplasma gondii; cat; phosphoproteomics; post-translational modification

DOI:  https://doi.org/10.3390/ani13223537
Vaccines (Basel). 2023 Nov 02. pii: 1678. [Epub ahead of print]11(11):

Boosting Mouse Defense against Lethal Toxoplasma gondii Infection with Full-Length and Soluble SAG1 Recombinant Protein.

Xiang Li, Wei Yuan, Ting He, Ruiying Guo, Xiuxian Du, Yanhong He, Xuan Li, Saeed El-Ashram, Ebtesam M Al-Olayan, Na Yang, Xiaoyu Sang.

  Toxoplasmosis is a major worldwide protozoan zoonosis. The surface antigen 1 (SAG1) of Toxoplasma gondii (T. gondii) has always been recognized as an ideal vaccine candidate antigen. However, the intact and soluble SAG1 protein is usually difficult to acquire in vitro, which is unfavorable for employing the recombinant protein as a vaccine candidate antigen. In the present study, we obtained the full-length SAG1 recombinant protein in soluble form by Escherichia coli Transetta (DE3) cells under optimized expression conditions. The immunogenicity and protective ability of this recombinant protein against T. gondii acute infection were evaluated in a mouse model. Monitoring changes in serum antibody levels and types, the presence of cytokines, and the rate of lymphocyte proliferation in vaccinated mice were used to assess humoral and cellular immune responses. Additional assessments were performed to determine the protective potency of the recombinant protein in combating T. gondii RH tachyzoites. It was found that the titers of both IgG2a and IgG2b were considerably greater in the immunized mice compared to the titers of IgG1 and IgG3. The levels of Th1-type cytokines (IFN-γ, IL-12p70, IL-2, and TNF-α) and Th2-type cytokines (IL-10) significantly increased when splenocytes from immunological group mice were treated with T. gondii lysate antigen. Compared to the control group, a recombinant protein substantially increased the longevity of infected mice, with an average death time prolonged by 14.50 ± 0.34 days (p < 0.0001). These findings suggest that the full-length and soluble SAG1 recombinant protein produced potent immune responses in mice and could be a preferred subunit vaccine candidate for T. gondii, offering a feasible option for vaccination against acute toxoplasmosis.

Keywords:  SAG1; Toxoplasma gondii; defense; full-length; mouse

DOI:  https://doi.org/10.3390/vaccines11111678
Genes Cells. 2023 Nov 20.

Structural basis of Irgb6 inactivation by Toxoplasma gondii through the phosphorylation of switch I.

Hiromichi Okuma, Yumiko Saijo-Hamano, Hiroshi Yamada, Aalaa Alrahman Sherif, Emi Hashizaki, Naoki Sakai, Takaaki Kato, Tsuyoshi Imasaki, Satoshi Kikkawa, Eriko Nitta, Miwa Sasai, Tadashi Abe, Fuminori Sugihara, Yoshimasa Maniwa, Hidetaka Kosako, Kohji Takei, Daron M Standley, Masahiro Yamamoto, Ryo Nitta.

  Irgb6 is a priming immune-related GTPase (IRG) that counteracts Toxoplasma gondii. It is known to be recruited to the low virulent type II T. gondii parasitophorous vacuole (PV), initiating cell-autonomous immunity. However, the molecular mechanism by which immunity-related GTPases become inactivated after the parasite infection remains obscure. Here, we found that Thr95 of Irgb6 is prominently phosphorylated in response to low virulent type II T. gondii infection. We observed that a phosphomimetic T95D mutation in Irgb6 impaired its localization to the PV and exhibited reduced GTPase activity in vitro. Structural analysis unveiled an atypical conformation of nucleotide-free Irgb6-T95D, resulting from a conformational change in the G-domain that allosterically modified the PV membrane-binding interface. In silico docking corroborated the disruption of the physiological membrane binding site. These findings provide novel insights into a T. gondii-induced allosteric inactivation mechanism of Irgb6.

Keywords:  Irgb6; Toxoplasma gondii; allosteric conformational change; immune-related GTPase; phosphorylation; x-ray crystallography

DOI:  https://doi.org/10.1111/gtc.13080
Parasit Vectors. 2023 Nov 21. 16(1): 431

Analysis of codon usage bias of thioredoxin in apicomplexan protozoa.

Dawei Wang, Baoling Yang.

  BACKGROUND: Apicomplexan protozoa are a diverse group of obligate intracellular parasites causing many diseases that affect humans and animals, such as malaria, toxoplasmosis, and cryptosporidiosis. Apicomplexan protozoa possess unique thioredoxins (Trxs) that have been shown to regulate various cellular processes including metabolic redox regulation, parasite survival, and host immune evasion. However, it is still unknown how synonymous codons are used by apicomplexan protozoa Trxs.METHODS: Codon usage bias (CUB) is the unequal usage of synonymous codons during translation which leads to the over- or underrepresentation of certain nucleotide patterns. This imbalance in CUB can impact a variety of cellular processes including protein expression levels and genetic variation. This study analyzed the CUB of 32 Trx coding sequences (CDS) from 11 apicomplexan protozoa.
RESULTS: The results showed that both codon base composition and relative synonymous codon usage (RSCU) analysis revealed that AT-ended codons were more frequently used in Cryptosporidium spp. and Plasmodium spp., while the Eimeria spp., Babesia spp., Hammondia hammondi, Neospora caninum, and Toxoplasma gondii tended to end in G/C. The average effective number of codon (ENC) value of these apicomplexan protozoa is 46.59, which is > 35, indicating a weak codon preference among apicomplexan protozoa Trxs. Furthermore, the correlation analysis among codon base composition (GC1, GC2, GC3, GCs), codon adaptation index (CAI), codon bias index (CBI), frequency of optimal codons (FOP), ENC, general average hydropathicity (GRAVY), aromaticity (AROMO), length of synonymous codons (L_sym), and length of amino acids (L_aa) indicated the influence of base composition and codon usage indices on CUB. Additionally, the neutrality plot analysis, PR2-bias plot analysis, and ENC-GC3 plot analysis further demonstrated that natural selection plays an important role in apicomplexan protozoa Trxs codon bias.
CONCLUSIONS: In conclusion, this study increased the understanding of codon usage characteristics and genetic evolution of apicomplexan protozoa Trxs, which expanded new ideas for vaccine and drug research.

Keywords:  Apicomplexan Protozoa; Codon usage bias; Effective number of codons; Relative synonymous codon usage; Thioredoxin

DOI:  https://doi.org/10.1186/s13071-023-06002-w
Xenobiotica. 2023 Nov 22. 1-11

Chronic Toxoplasma infection affects gene expression of drug-metabolizing enzymes in mouse liver.

Yasuhiro Uno, Shotaro Uehara, Genki Ushirozako, Tatsunori Masatani, Hiroshi Yamazaki.

  Toxoplasma gondii is an intracellular protozoan parasite causing toxoplasmosis, an infectious disease affecting warm-blooded vertebrates worldwide. Many drug-metabolizing enzymes are located in the liver, a major organ of drug metabolism, and their function can be affected by pathogen infection.Using next-generation sequencing (RNA-seq) and quantitative polymerase chain reaction (qPCR), changes in the hepatic expressions of drug-metabolizing enzymes were analyzed in mice chronically infected with T. gondii. The analysis found that, among drug-metabolizing enzymes, 22 genes were upregulated and 28 genes were downregulated (≥1.5-fold); of these 5 and 17 genes, respectively, were cytochromes P450 (Cyp or P450).Subsequent qPCR analysis showed that six P450 genes were upregulated significantly (≥1.5-fold, P < 0.05), namely, Cyp1b1, Cyp2c29, Cyp2c65, Cyp2d9, Cyp2d12, and Cyp3a59, whereas nine P450 genes were downregulated significantly (≥1.5-fold, P < 0.05), namely, Cyp2c38, Cyp2c39, Cyp2c44, Cyp2c69, Cyp2d40, Cyp2e1, Cyp3a11, Cyp3a41, and Cyp3a44.Moreover, metabolic assays in infected mouse liver using typical P450 substrates revealed that midazolam 1'-hydroxylation and testosterone 2-hydroxylation activities decreased significantly (≥1.5-fold, P < 0.05), whereas testosterone 16-hydroxylation activity increased significantly (≥1.5-fold, P < 0.05).Chronic Toxoplasma infection affects drug metabolism, at least partly, by altering the gene expressions of drug-metabolizing enzymes, including P450s.

Keywords:  RNA-seq; Toxoplasma infection; cytochrome P450; drug-metabolizing enzymes; mouse liver

DOI:  https://doi.org/10.1080/00498254.2023.2286597
bioRxiv. 2023 Nov 11. pii: 2023.11.10.566663. [Epub ahead of print]

Human trophoblast stem cells can be used to model placental susceptibility to Toxoplasma gondii and highlight the critical importance of the trophoblast cell surface in pathogen resistance.

Rafaela J da Silva, Leah F Cabo, Jada L George, Laty A Cahoon, Liheng Yang, Carolyn B Coyne, Jon P Boyle.

The placenta is a critical barrier against viral, bacterial, and eukaryotic pathogens. For most teratogenic pathogens, the precise molecular mechanisms of placental resistance are still being unraveled. Given the importance to understand these mechanisms and challenges in replicating trophoblast- pathogen interactions using in vitro models, we tested an existing stem-cell derived model of trophoblast development for its relevance to infection with Toxoplasma gondii . We grew human trophoblast stem cells (TS CT ) under conditions leading to either syncytiotrophoblast (TS SYN ) or cytotrophoblast (TS CYT ) and infected them with T. gondii . We evaluated T. gondii proliferation and invasion, cell ultrastructure, as well as for transcriptome changes after infection. TS SYNs cells showed similar ultrastructure compared to primary cells and villous explants when analyzed by TEM and SEM, a resistance to T. gondii adhesion could be visualized on the SEM level. Furthermore, TS SYNs were highly refractory to parasite adhesion and replication, while TS CYT were not. RNA-seq data on mock-treated and infected cells identified differences between cell types as well as how they responded to T. gondii infection. We also evaluated if TS SC -derived SYNs and CYTs had distinct resistance profiles to another vertically transmitted facultative intracellular pathogen, Listeria monocytogenes . We demonstrate that TS SYNs are highly resistant to L. monocytogenes , while TS CYTs are not. Like T. gondii , TS SYN resistance to L. monocytogenes was at the level of bacterial adhesion. Altogether, our data indicate that stem-cell derived trophoblasts recapitulate resistance profiles of primary cells to T. gondii and highlight the critical importance of the placental surface in cell-autonomous resistance to teratogens.

DOI: https://doi.org/10.1101/2023.11.10.566663
PLoS Pathog. 2023 Nov;19(11): e1011770

Protein kinase PfPK2 mediated signalling is critical for host erythrocyte invasion by malaria parasite.

Rahul Singh Rawat, Ankit Gupta, Neelam Antil, Sonika Bhatnagar, Monika Singh, Akanksha Rawat, T S Keshava Prasad, Pushkar Sharma.

Signalling pathways in malaria parasite remain poorly defined and major reason for this is the lack of understanding of the function of majority of parasite protein kinases and phosphatases in parasite signalling and its biology. In the present study, we have elucidated the function of Protein Kinase 2 (PfPK2), which is known to be indispensable for the survival of human malaria parasite Plasmodium falciparum. We demonstrate that it is involved in the invasion of host erythrocytes, which is critical for establishing infection. In addition, PfPK2 may also be involved in the maturation of the parasite post-invasion. PfPK2 regulates the release of microneme proteins like Apical Membrane Antigen 1 (AMA1), which facilitates the formation of Tight Junction between the merozoite and host erythrocyte- a key step in the process of invasion. Comparative phosphoproteomics studies revealed that PfPK2 may be involved in regulation of several key proteins involved in invasion and signalling. Furthermore, PfPK2 regulates the generation of cGMP and the release of calcium in the parasite, which are key second messengers for the process of invasion. These and other studies have shed light on a novel signalling pathway in which PfPK2 acts as an upstream regulator of important cGMP-calcium signalling, which plays an important role in parasite invasion.

DOI: https://doi.org/10.1371/journal.ppat.1011770
Eur J Microbiol Immunol (Bp). 2023 Nov 23. 13(3): 77-82

Toxoplasma gondii infection of the central nervous system and suicide: A case-control study of decedents.

Laura Alejandra Mendoza-Larios, Fernando García-Dolores, Luis Francisco Sánchez-Anguiano, Elizabeth Irasema Antuna-Salcido, Jesús Hernández-Tinoco, Adriana Rocha-Salais, Marcela Araceli Segoviano-Mendoza, Antonio Sifuentes-Álvarez, Cosme Alvarado-Esquivel.

  We sought to determine the association between Toxoplasma gondii (T. gondii) infection of the central nervous system and suicide in a sample of decedents in Mexico City. One hundred and forty-seven decedents (87 who committed suicide and 60 who did not commit suicide) were studied. Brain tissues (amygdala and prefrontal cortex) of decedents were examined for the detection of T. gondii using immunohistochemistry. Detection of T. gondii was positive in 7 (8.0%) of the 87 cases (6 found in prefrontal cortex and one in amygdala), and in one (1.7%) of the 60 controls (found in prefrontal cortex) (OR: 5.16; 95% CI: 0.61-43.10; P = 0.14). Results suggest that T. gondii infection in brain is not associated with suicide. Further studies to confirm this finding are needed.

Keywords:  Toxoplasma gondii; case-control study; epidemiology; immunohistochemistry; suicide

DOI:  https://doi.org/10.1556/1886.2023.00033
Int Immunopharmacol. 2023 Nov 22. pii: S1567-5769(23)01581-3. [Epub ahead of print]126 111254

Protective effect of arctiin against Toxoplasma gondii HSP70-induced allergic acute liver injury by disrupting the TLR4-mediated activation of cytosolic phospholipase A2 and platelet-activating factor.

Jing-Mei Lu, Xiang Xu, Fumie Aosai, Ming-Yue Zhang, Lu-Lu Zhou, Lian-Xun Piao.

  Toxoplasma gondii (T. gondii)-derived heat shock protein 70 (T.g.HSP70) is a toxic protein that downregulates host defense responses against T. gondii infection. T.g.HSP70 was proven to induce fatal anaphylaxis in T. gondii infected mice through cytosolic phospholipase A2 (cPLA2) activated-platelet-activating factor (PAF) production via Toll-like receptor 4 (TLR4)-mediated signaling. In this study, we investigated the effect of arctiin (ARC; a major lignan compound of Fructus arctii) on allergic liver injury using T.g.HSP70-stimulated murine liver cell line (NCTC 1469) and a mouse model of T. gondii infection. Localized surface plasmon resonance, ELISA, western blotting, co-immunoprecipitation, and immunofluorescence were used to investigate the underlying mechanisms of action of ARC on T. gondii-induced allergic acute liver injury. The results showed that ARC suppressed the T.g.HSP70-induced allergic liver injury in a dose-dependent manner. ARC could directly bind to T.g.HSP70 or TLR4, interfering with the interaction between these two factors, and inhibiting activation of the TLR4/mitogen-activated protein kinase/nuclear factor-kappa B signaling, thereby inhibiting the overproduction of cPLA2, PAF, and interferon-γ. This result suggested that ARC ameliorates T.g.HSP70-induced allergic acute liver injury by disrupting the TLR4-mediated activation of inflammatory mediators, providing a theoretical basis for ARC therapy to improve T.g.HSP70-induced allergic liver injury.

Keywords:  Allergic liver injury; Arctiin; T. gondii HSP70; TLR4; Toxoplasma gondii; cPLA(2)

DOI:  https://doi.org/10.1016/j.intimp.2023.111254
Molecules. 2023 Nov 18. pii: 7655. [Epub ahead of print]28(22):

5-((3-Amidobenzyl)oxy)nicotinamides as SIRT2 Inhibitors: A Study of Constrained Analogs.

Teng Ai, Daniel J Wilson, Liqiang Chen.

  SIRT2 is a member of NAD+-dependent sirtuins and its inhibition has been proposed as a promising therapeutic approach for treating human diseases, including neurodegenerative diseases, cancer, and infections. Expanding SIRT2 inhibitors based on the 3-aminobenzyloxy nicotinamide core structure, we have synthesized and evaluated constrained analogs and selected stereoisomers. Our structure-activity relationship (SAR) study has revealed that 2,3-constrained (S)-isomers possess enhanced in vitro enzymatic inhibitory activity against SIRT2 and retain excellent selectivity over SIRT1 and SIRT3, provided that a suitable ring A is used. This current study further explores SIRT2 inhibitors based on the 3-aminobenzyloxy nicotinamide scaffold and contributes to the discovery of potent, selective SIRT2 inhibitors that have been actively pursued for their potential therapeutic applications.

Keywords:  SIRT1; SIRT2; SIRT3; constrained inhibitors; sirtuin inhibitors; sirtuins

DOI:  https://doi.org/10.3390/molecules28227655
Pathogens. 2023 Nov 18. pii: 1367. [Epub ahead of print]12(11):

Implications of Flagellar Attachment Zone Proteins TcGP72 and TcFLA-1BP in Morphology, Proliferation, and Intracellular Dynamics in Trypanosoma cruzi.

Normanda Souza-Melo, Carolina de Lima Alcantara, Juliana Cunha Vidal, Gustavo Miranda Rocha, Wanderley de Souza.

  The highly adaptable parasite Trypanosoma cruzi undergoes complex developmental stages to exploit host organisms effectively. Each stage involves the expression of specific proteins and precise intracellular structural organization. These morphological changes depend on key structures that control intracellular components' growth and redistribution. In trypanosomatids, the flagellar attachment zone (FAZ) connects the flagellum to the cell body and plays a pivotal role in cell expansion and structural rearrangement. While FAZ proteins are well-studied in other trypanosomatids, there is limited knowledge about specific components, organization, and function in T. cruzi. This study employed the CRISPR/Cas9 system to label endogenous genes and conduct deletions to characterize FAZ-specific proteins during epimastigote cell division and metacyclogenesis. In T. cruzi, these proteins exhibited distinct organization compared to their counterparts in T. brucei. TcGP72 is anchored to the flagellar membrane, while TcFLA-1BP is anchored to the membrane lining the cell body. We identified unique features in the organization and function of the FAZ in T. cruzi compared to other trypanosomatids. Deleting these proteins had varying effects on intracellular structures, cytokinesis, and metacyclogenesis. This study reveals specific variations that directly impact the success of cell division and differentiation of this parasite.

Keywords:  CRISPR/Cas9; flagellar attachment zone; morphological changes

DOI:  https://doi.org/10.3390/pathogens12111367
Int J Mol Sci. 2023 Nov 11. pii: 16210. [Epub ahead of print]24(22):

The Role of Sirtuin-1 (SIRT1) in the Physiology and Pathophysiology of the Human Placenta.

Mateusz Wątroba, Grzegorz Szewczyk, Dariusz Szukiewicz.

  Sirtuins, especially SIRT1, play a significant role in regulating inflammatory response, autophagy, and cell response to oxidative stress. Since their discovery, sirtuins have been regarded as anti-ageing and longevity-promoting enzymes. Sirtuin-regulated processes seem to participate in the most prevalent placental pathologies, such as pre-eclampsia. Furthermore, more and more research studies indicate that SIRT1 may prevent pre-eclampsia development or at least alleviate its manifestations. Having considered this, we reviewed recent studies on the role of sirtuins, especially SIRT1, in processes determining normal or abnormal development and functioning of the placenta.

Keywords:  PPARγ; SIRT1; SIRT1/PPARγ signaling; human placenta; peroxisome proliferator-activated receptor γ; placental pathophysiology; placental physiology; pre-eclampsia; sirtuin-1; sirtuins

DOI:  https://doi.org/10.3390/ijms242216210
Protein Sci. 2023 Nov 23. e4845

Characterizing Lysine Acetylation of Glucokinase.

Nour Fatema, Xinyu Li, Qinglei Gan, Chenguang Fan.

  Glucokinase (GK) catalyzes the phosphorylation of glucose to form glucose-6-phosphate as the substrate of glycolysis for energy production. Acetylation of lysine residues in Escherichia coli GK has been identified at multiple sites by a series of proteomic studies, but the impact of acetylation on GK functions remains largely unknown. In this study, we applied the genetic code expansion strategy to produce site-specifically acetylated GK variants which naturally exist in cells. Enzyme assays and kinetic analyses showed that lysine acetylation decreases the GK activity, mostly resulting from acetylation of K214 and K216 at the entrance of the active site, which impairs the binding of substrates. We also compared results obtained from the glutamine substitution method and the genetic acetyllysine incorporation approach, showing that glutamine substitution is not always effective for mimicking acetylated lysine. Further genetic studies as well as in vitro acetylation and deacetylation assays were performed to determine acetylation and deacetylation mechanisms, which showed that E. coli GK could be acetylated by acetyl-phosphate without enzymes and deacetylated by CobB deacetylase. This article is protected by copyright. All rights reserved.

Keywords:  deacetylase; genetic code expansion; glucokinase; glycolysis; lysine acetylation

DOI:  https://doi.org/10.1002/pro.4845
Microorganisms. 2023 Oct 31. pii: 2671. [Epub ahead of print]11(11):

Changes in the Proliferation of the Neural Progenitor Cells of Adult Mice Chronically Infected with Toxoplasma gondii.

Verónica Anaya-Martínez, Jhony Anacleto-Santos, Ricardo Mondragón-Flores, Armando Zepeda-Rodríguez, Brenda Casarrubias-Tabarez, Teresa de Jesús López-Pérez, Mariana Citlalli de Alba-Alvarado, Cintli Martínez-Ortiz-de-Montellano, Elba Carrasco-Ramírez, Norma Rivera-Fernández.

  During Toxoplasma gondii chronic infection, certain internal factors that trigger the proliferation of neural progenitor cells (NPCs), such as brain inflammation, cell death, and changes in cytokine levels, are observed. NPCs give rise to neuronal cell types in the adult brain of some mammals. NPCs are capable of dividing and differentiating into a restricted repertoire of neuronal and glial cell types. In this study, the proliferation of NPCs was evaluated in CD-1 adult male mice chronically infected with the T. gondii ME49 strain. Histological brain sections from the infected mice were evaluated in order to observe T. gondii tissue cysts. Sagittal and coronal sections from the subventricular zone of the lateral ventricles and from the subgranular zone of the hippocampal dentate gyrus, as well as sagittal sections from the rostral migratory stream, were obtained from infected and non-infected mice previously injected with bromodeoxyuridine (BrdU). A flotation immunofluorescence technique was used to identify BrdU+ NPC. The scanning of BrdU+ cells was conducted using a confocal microscope, and the counting was performed with ImageJ® software (version 1.48q). In all the evaluated zones from the infected mice, a significant proliferation of the NPCs was observed when compared with that of the control group. We concluded that chronic infection with T. gondii increased the proliferation of NPCs in the three evaluated zones. Regardless of the role these cells are playing, our results could be useful to better understand the pathogenesis of chronic toxoplasmosis.

Keywords:  Toxoplasma gondii; chronic toxoplasmosis; neural progenitor cells; neurogenesis

DOI:  https://doi.org/10.3390/microorganisms11112671
Pharmaceutics. 2023 Nov 03. pii: 2581. [Epub ahead of print]15(11):

Targeting Histone Deacetylases 6 in Dual-Target Therapy of Cancer.

Milan Beljkas, Aleksandra Ilic, Alen Cebzan, Branko Radovic, Nemanja Djokovic, Dusan Ruzic, Katarina Nikolic, Slavica Oljacic.

  Histone deacetylases (HDACs) are the major regulators of the balance of acetylation of histone and non-histone proteins. In contrast to other HDAC isoforms, HDAC6 is mainly involved in maintaining the acetylation balance of many non-histone proteins. Therefore, the overexpression of HDAC6 is associated with tumorigenesis, invasion, migration, survival, apoptosis and growth of various malignancies. As a result, HDAC6 is considered a promising target for cancer treatment. However, none of selective HDAC6 inhibitors are in clinical use, mainly because of the low efficacy and high concentrations used to show anticancer properties, which may lead to off-target effects. Therefore, HDAC6 inhibitors with dual-target capabilities represent a new trend in cancer treatment, aiming to overcome the above problems. In this review, we summarize the advances in tumor treatment with dual-target HDAC6 inhibitors.

Keywords:  cancer; dual-target therapy; epigenetics; histone deacetylases; inhibitors; kinases; rational design

DOI:  https://doi.org/10.3390/pharmaceutics15112581
Plant Physiol. 2023 Nov 18. pii: kiad614. [Epub ahead of print]

The role of histone acetylation in transcriptional regulation and seed development.

Yan Chen, Peiguo Guo, Zhicheng Dong.

  Histone acetylation is highly conserved across eukaryotes and has been linked to gene activation since its discovery nearly 60 years ago. Over the past decades, histone acetylation has been evidenced to play crucial roles in the plant development and response to various environmental cues. Emerging data indicate that histone acetylation is one of the defining features of "open chromatin", while the role of histone acetylation in transcription remains controversial. In this review, we briefly describe the discovery of histone acetylation, the mechanism of histone acetylation regulating transcription in yeast and mammals, and summarize the research progress of plant histone acetylation. Furthermore, we also emphasized the effect of histone acetylation on seed development and its potential use in plant breeding. A comprehensive knowledge of histone acetylation might provide new and more flexible research perspectives to enhance crop yield and stress resistance.

Keywords:  chromatin; histone acetylation; plant breeding; seed development; transcription regulation

DOI:  https://doi.org/10.1093/plphys/kiad614
Biology (Basel). 2023 Oct 26. pii: 1370. [Epub ahead of print]12(11):

Crystal Structures Reveal Hidden Domain Mechanics in Protein Kinase A (PKA).

Colin L Welsh, Abigail E Conklin, Lalima K Madan.

  Cyclic-AMP-dependent protein kinase A (PKA) is a critical enzyme involved in various signaling pathways that plays a crucial role in regulating cellular processes including metabolism, gene transcription, cell proliferation, and differentiation. In this study, the mechanisms of allostery in PKA were investigated by analyzing the vast repertoire of crystal structures available in the RCSB database. From existing structures of murine and human PKA, we elucidated the conformational ensembles and protein dynamics that are altered in a ligand-dependent manner. Distance metrics to analyze conformations of the G-loop were proposed to delineate different states of PKA and were compared to existing structural metrics. Furthermore, ligand-dependent flexibility was investigated through normalized B'-factors to better understand the inherent dynamics in PKA. The presented study provides a contemporary approach to traditional methods in engaging the use of crystal structures for understanding protein dynamics. Importantly, our studies provide a deeper understanding into the conformational ensemble of PKA as the enzyme progresses through its catalytic cycle. These studies provide insights into kinase regulation that can be applied to both PKA individually and protein kinases as a class.

Keywords:  catalytic domain; crystal B-factors; kinase structure; protein kinase (A); protein kinases; structural dynamics

DOI:  https://doi.org/10.3390/biology12111370
Autophagy. 2023 Nov 22.

ULK1 seen at the single-molecule level during autophagy initiation.

Chiranjib Banerjee, Elias M Puchner, Do-Hyung Kim.

  Macroautophagy/autophagy research often involves overexpressing proteins to investigate their localization, function and activity. However, this approach can disturb the inherent balance of cellular components, potentially affecting the integrity of the autophagy process. With the advent of genome-editing techniques like CRISPR-Cas9, it is now possible to tag endogenous proteins with fluorescent markers, enabling the study of their behaviors under more physiologically relevant conditions. Nevertheless, conventional microscopy methods have limitations in characterizing the behaviors of proteins expressed at endogenous levels. This challenge can be overcome by single-molecule localization microscopy (SMLM) methods, which provide single-molecule sensitivity and super-resolution imaging capabilities. In our recent study, we used SMLM in combination with genome editing to explore the behavior of endogenous ULK1 during autophagy initiation, yielding unprecedented insights into the autophagy initiation process.

Keywords:  Genome editing; PALM; SMLM; ULK1; single molecule

DOI:  https://doi.org/10.1080/15548627.2023.2286078
Int J Biol Macromol. 2023 Nov 22. pii: S0141-8130(23)05169-3. [Epub ahead of print] 128270

Sirtuins in macrophage immune metabolism: A novel target for cardiovascular disorders.

Chen-Qin Xu, Ji Li, Zhi-Qiang Liang, Yi-Lang Zhong, Zhi-Hui Zhang, Xue-Qing Hu, Yong-Bing Cao, Jian Chen.

  Sirtuins (SIRT1-SIRT7), as a family of NAD + -dependent protein modifying enzymes, have various catalytic functions, such as deacetylases, dealkalylases, and deribonucleases. The Sirtuins family is directly or indirectly involved in pathophysiological processes such as glucolipid metabolism, oxidative stress, DNA repair and inflammatory response through various pathways and assumes an important role in several cardiovascular diseases such as atherosclerosis, myocardial infarction, hypertension and heart failure. A growing number of studies supports that metabolic and bioenergetic reprogramming directs the sequential process of inflammation. Failure of homeostatic restoration leads to many inflammatory diseases, and that macrophages are the central cells involving the inflammatory response and are the main source of inflammatory cytokines. Regulation of cellular metabolism has emerged as a fundamental process controlling macrophage function, but its exact signaling mechanisms remain to be revealed. Understanding the precise molecular basis of metabolic control of macrophage inflammatory processes may provide new approaches for targeting immune metabolism and inflammation. Here, we provide an update of studies in cardiovascular disease on the function and role of sirtuins in macrophage inflammation and metabolism, as well as drug candidates that may interfere with sirtuins, pointing to future prospects in this field.

Keywords:  Cardiovascular; Immune metabolism; Inflammation; Macrophage; Sirtuin

DOI:  https://doi.org/10.1016/j.ijbiomac.2023.128270