bims-unfpre 2024-09-08 papers

bims-unfpre

Biomed News

on Unfolded protein response

Issue of 2024–09–08
eight papers selected by
Susan Logue, University of Manitoba

Disordered regions in the IRE1α ER lumenal domain mediate its stress-induced clustering.
High-grade serous ovarian cancer development and anti-PD-1 resistance is driven by IRE1α activity in neutrophils.
The Role of Endoplasmic Reticulum Stress on Reducing Recombinant Protein Production in Mammalian Cells.
The Q for immune evasion in HCC: ER stress in myeloid cells.
Investigation of endoplasmic reticulum stress-regulated chaperones as biomarkers in idiopathic non-obstructive azoospermia.
Small GTP-binding protein GDP dissociation stimulator influences cisplatin-induced acute kidney injury via PERK-dependent ER stress.
ER-associated degradation ligase HRD1 links ER stress to DNA damage repair by modulating the activity of DNA-PKcs.
GRP78 via releasing β-catenin from adherens junctions facilitates its interaction with STAT3 in mediating retinal neovascularization.

EMBO J. 2024 Sep 04.

Disordered regions in the IRE1α ER lumenal domain mediate its stress-induced clustering.

Paulina Kettel, Laura Marosits, Elena Spinetti, Michael Rechberger, Caterina Giannini, Philipp Radler, Isabell Niedermoser, Irmgard Fischer, Gijs A Versteeg, Martin Loose, Roberto Covino, G Elif Karagöz.

  Conserved signaling cascades monitor protein-folding homeostasis to ensure proper cellular function. One of the evolutionary conserved key players is IRE1, which maintains endoplasmic reticulum (ER) homeostasis through the unfolded protein response (UPR). Upon accumulation of misfolded proteins in the ER, IRE1 forms clusters on the ER membrane to initiate UPR signaling. What regulates IRE1 cluster formation is not fully understood. Here, we show that the ER lumenal domain (LD) of human IRE1α forms biomolecular condensates in vitro. IRE1α LD condensates were stabilized both by binding to unfolded polypeptides as well as by tethering to model membranes, suggesting their role in assembling IRE1α into signaling-competent stable clusters. Molecular dynamics simulations indicated that weak multivalent interactions drive IRE1α LD clustering. Mutagenesis experiments identified disordered regions in IRE1α LD to control its clustering in vitro and in cells. Importantly, dysregulated clustering of IRE1α mutants led to defects in IRE1α signaling. Our results revealed that disordered regions in IRE1α LD control its clustering and suggest their role as a common strategy in regulating protein assembly on membranes.

Keywords:  Biomolecular Condensates; IRE1; Supported Lipid Bilayers; Unfolded Protein Response

DOI:  https://doi.org/10.1038/s44318-024-00207-0
bioRxiv. 2024 Aug 07. pii: 2024.08.05.606646. [Epub ahead of print]

High-grade serous ovarian cancer development and anti-PD-1 resistance is driven by IRE1α activity in neutrophils.

Alexander Emmanuelli, Camilla Salvagno, Sung Min-Hwang, Deepika Awasthi, Tito A Sandoval, Chang-Suk Chae, Jin-Gyu Cheong, Chen Tan, Takao Iwawaki, Juan R Cubillos-Ruiz.

High-grade serous ovarian cancer (HGSOC) is an aggressive malignancy that remains refractory to current immunotherapies. While advanced stage disease has been extensively studied, the cellular and molecular mechanisms that promote early immune escape in HGSOC remain largely unexplored. Here we report that primary HGSO tumors program neutrophils to inhibit T cell anti-tumor function by activating the endoplasmic reticulum (ER) stress sensor IRE1α. We found that intratumoral neutrophils exhibited overactivation of ER stress response markers compared with their counterparts at non-tumor sites. Selective deletion of IRE1α in neutrophils delayed primary ovarian tumor growth and extended the survival of mice with HGSOC by enabling early T cell-mediated tumor control. Notably, loss of IRE1α in neutrophils sensitized tumor-bearing mice to PD-1 blockade, inducing HGSOC regression and long-term survival in ∼50% of treated hosts. Hence, neutrophil-intrinsic IRE1α facilitates early adaptive immune escape in HGSOC and targeting this ER stress sensor might be used to unleash endogenous and immunotherapy-elicited immunity that controls metastatic disease.

DOI: https://doi.org/10.1101/2024.08.05.606646
Biochem Eng J. 2024 Oct;pii: 109434. [Epub ahead of print]210

The Role of Endoplasmic Reticulum Stress on Reducing Recombinant Protein Production in Mammalian Cells.

R Chauncey Splichal, Kevin Chen, S Patrick Walton, Christina Chan.

  Therapeutic recombinant protein production relies on industrial scale culture of mammalian cells to produce active proteins in quantities sufficient for clinical use. The combination of stresses from industrial cell culture environment and recombinant protein production can overwhelm the protein synthesis machinery in the endoplasmic reticulum (ER). This leads to a buildup of improperly folded proteins which induces ER stress. Cells respond to ER stress by activating the Unfolded Protein Response (UPR). To restore proteostasis, ER sensor proteins reduce global protein synthesis and increase chaperone protein synthesis, and if that is insufficient the proteins are degraded. If proteostasis is still not restored, apoptosis is initiated. Increasing evidence suggests crosstalk between ER proteostasis and DNA damage repair (DDR) pathways. External factors (e.g., metabolites) from the cellular environment as well as internal factors (e.g., transgene copy number) can impact genome stability. Failure to maintain genome integrity reduces cell viability and in turn protein production. This review focuses on the association between ER stress and processes that affect protein production and secretion. The processes mediated by ER stress, including inhibition of global protein translation, chaperone protein production, degradation of misfolded proteins, DNA repair, and protein secretion, impact recombinant protein production. Recombinant protein production can be reduced by ER stress through increased autophagy and protein degradation, reduced protein secretion, and reduced DDR response.

Keywords:  DNA Damage Response; Endoplasmic reticulum stress; Industrial Cell Culture; Protein Production; Secretion

DOI:  https://doi.org/10.1016/j.bej.2024.109434
Gut. 2024 Aug 29. pii: gutjnl-2024-333249. [Epub ahead of print]

The Q for immune evasion in HCC: ER stress in myeloid cells.

Charlotte Rennert, Maike Hofmann.



Keywords:  AMINO ACIDS; HEPATOCELLULAR CARCINOMA; IMMUNE RESPONSE; MACROPHAGES; T LYMPHOCYTES

DOI:  https://doi.org/10.1136/gutjnl-2024-333249
Cell Stress Chaperones. 2024 Sep 03. pii: S1355-8145(24)00115-9. [Epub ahead of print]

Investigation of endoplasmic reticulum stress-regulated chaperones as biomarkers in idiopathic non-obstructive azoospermia.

Cigdem Cicek, Pelin Telkoparan-Akillilar, Semra Sertyel, Cumhur Bilgi, Osman Denizhan Ozgun.

  Azoospermia is a condition in which sperm cells are completely absent in a male's ejaculate. Typically, sperm production occurs in the testes and is regulated by a complex series of cellular and molecular interactions. Endoplasmic reticulum (ER) stress arises when there is deviation from or damage to the normal functions of the ER within cells. In response to this stress, a cascade of response mechanisms is activated to regulate ER stress within cells. This study aims to investigate the role of endoplasmic reticulum (ER) stress-regulated chaperones as potential biomarkers in male infertility. ER stress associated with azoospermia can manifest in cells such as spermatogonia in the testes and can impact sperm production. As a result of ER stress, the expression and activity of a variety of proteins within cells can be altered. Among these proteins are chaperone proteins that regulate the ER stress response. The sample size was calculated to be a minimum of 36 patients each groups. In this preliminary study, we measured and compared serum levels of protein disulfide-isomerase A1 (PDI1), protein disulfide-isomerase A3 (PDIA3), mesencephalic astrocyte-derived neurotrophic factor (MANF), glucose regulatory protein 78 (GRP78), clusterin (CLU), calreticulin (CRT), and calnexin (CNX) between male subjects with idiopathic non-obstructive azoospermia and a control group of non-infertile males. Serum PDIA1 (p=0.0004), MANF (p=0.018), PDIA3 (p<0.0001), GRP78 (p=0.0027), CRT (p=0.0009) levels were higher in the infertile group compared to the control. In summary, this study presents novel findings in a cohort of male infertile patients, emphasizing the significance of incorporating diverse biomarkers. It underscores the promising role of ER stress-regulated proteins as potential serum indicators for male infertility. By elucidating the impact of ER stress on spermatogenic cells, the research illuminates the maintenance or disruption of cellular health. A deeper understanding of these results could open the door to novel treatment approaches for reproductive conditions including azoospermia.

Keywords:  Endoplasmic reticulum chaperones; Endoplasmic reticulum stress; Idiopathic non abstructive azoospermia; Male infertility

DOI:  https://doi.org/10.1016/j.cstres.2024.08.004
Commun Biol. 2024 Sep 05. 7(1): 1091

Small GTP-binding protein GDP dissociation stimulator influences cisplatin-induced acute kidney injury via PERK-dependent ER stress.

Yuxue Yang, Ting Xiong, Ti Wang, Xiwei Chen, Ziwei Ma, Bangyun Zuo, Dong Ning, Ruilong Song, Xuesong Liu, Daxin Wang.

Cisplatin is a common anticancer drug, but its frequent nephrotoxicity limits its clinical use. Small GTP-binding protein GDP dissociation stimulator (smgGDS), a small GTPase chaperone protein, was considerably downregulated during cisplatin-induced acute kidney injury (CDDP-AKI), especially in renal tubular epithelial cells. SmgGDS-knockdown mice was established and found that smgGDS knockdown promoted CDDP-AKI, as demonstrated by an increase in serum creatine, blood urea nitrogen levels and the appearance of tubular patterns. RNA sequencing suggested that protein kinase RNA-like ER kinase (PERK), which bridges mitochondria-associated ER membranes, was involved in smgGDS knockdown following CDDP-AKI, and then identified that smgGDS knockdown increased phosphorylated-PERK in vivo and in vitro. Furthermore, we confirmed that smgGDS deficiency aggravated apoptosis and ER stress in vivo and in vitro. And the ER stress inhibitor 4-Phenylbutyric acid and the inhibition of PERK phosphorylation mitigated smgGDS deficiency-induced ER stress related apoptosis following cisplatin treatment, while the eIF2α phosphorylation inhibitor could not reverse the smgGDS deficiency accelerated cell death. Furthermore, the over-expression of smgGDS could reverse the ER stress and apoptosis caused by CDDP. Overall, smgGDS regulated PERK-dependent ER stress and apoptosis, thereby influencing renal damage. This study identified a target for diagnosing and treating cisplatin-induced acute kidney injury.

DOI: https://doi.org/10.1038/s42003-024-06792-4
Proc Natl Acad Sci U S A. 2024 Sep 10. 121(37): e2403038121

ER-associated degradation ligase HRD1 links ER stress to DNA damage repair by modulating the activity of DNA-PKcs.

Zhiyuan Xiang, Guixue Hou, Shanliang Zheng, Minqiao Lu, Tianyu Li, Qingyu Lin, Hao Liu, Xingwen Wang, Tianqi Guan, Yuhan Wei, Wenxin Zhang, Yi Zhang, Chaoran Liu, Li Li, Qun-Ying Lei, Ying Hu.

  Proteostasis and genomic integrity are respectively regulated by the endoplasmic reticulum-associated protein degradation (ERAD) and DNA damage repair signaling pathways, with both pathways essential for carcinogenesis and drug resistance. How these signaling pathways coordinate with each other remains unexplored. We found that ER stress specifically induces the DNA-PKcs-regulated nonhomologous end joining (NHEJ) pathway to amend DNA damage and impede cell death. Intriguingly, sustained ER stress rapidly decreased the activity of DNA-PKcs and DNA damage accumulated, facilitating a switch from adaptation to cell death. This DNA-PKcs inactivation was caused by increased KU70/KU80 protein degradation. Unexpectedly, the ERAD ligase HRD1 was found to efficiently destabilize the classic nuclear protein HDAC1 in the cytoplasm, by catalyzing HDAC1's polyubiquitination at lysine 74, at a late stage of ER stress. By abolishing HDAC1-mediated KU70/KU80 deacetylation, HRD1 transmits ER signals to the nucleus. The resulting enhanced KU70/KU80 acetylation provides binding sites for the nuclear E3 ligase TRIM25, resulting in the promotion of polyubiquitination and the degradation of KU70/KU80 proteins. Both in vitro and in vivo cancer models showed that genetic or pharmacological inhibition of HADC1 or DNA-PKcs sensitizes colon cancer cells to ER stress inducers, including the Food and Drug Administration-approved drug celecoxib. The antitumor effects of the combined approach were also observed in patient-derived xenograft models. These findings identify a mechanistic link between ER stress (ERAD) in the cytoplasm and DNA damage (NHEJ) pathways in the nucleus, indicating that combined anticancer strategies may be developed that induce severe ER stress while simultaneously inhibiting KU70/KU80/DNA-PKcs-mediated NHEJ signaling.

Keywords:  DNA damage; HDAC1; KU70/KU80; TRIM25; endoplasmic reticulum stress

DOI:  https://doi.org/10.1073/pnas.2403038121
Am J Pathol. 2024 Aug 31. pii: S0002-9440(24)00324-9. [Epub ahead of print]

GRP78 via releasing β-catenin from adherens junctions facilitates its interaction with STAT3 in mediating retinal neovascularization.

Raj Kumar, Gadiparthi N Rao.

  Retinopathy due neovascularization is one of the major causes of vision loss. To understand the mechanisms underlying retinal neovascularization, using oxygen-induced retinopathy (OIR) model, we performed 2D gel-MALDI-TOF/TOF analysis of normoxic and 24-h post OIR mice pups' retinas. 2D gel analysis revealed that GRP78 is one of the several molecules induced by OIR in the retinal ECs. VEGFA also induced GRP78 expression independent of ER stress response in HRMVECs and depletion of its levels reduced VEGFA-induced EC angiogenic responses. Consistent with these observations, EC-specific deletion of GRP78 inhibited OIR-induced retinal neovascularization. In exploring the mechanisms, we found that GRP78 binds with VE-cadherin and releases adherens junction's but not Wnt-mediated β-catenin and that β-catenin, in turn, via interacting with STAT3 triggers cyclin D1 expression. Furthermore, depletion of β-catenin or cyclin D1 levels negated VEGFA-induced EC angiogenic responses and OIR-induced retinal neovascularization. EC-specific deletion of GRP78 also suppressed OIR-induced vascular leakage. In elucidating the upstream signaling, we found that ATF6 mediates GRP78 induction in the modulation of VEGFA-induced EC angiogenic responses and OIR-induced retinal neovascularization. Together, these observations reveal that GRP78 independent of its response to ER stress is involved in mediating EC angiogenic responses by VEGFA and retinal neovascularization by OIR. In view of these findings, it appears that GRP78 could be a desirable target for drug development against diabetic retinopathy.

Keywords:  GRP78; VEGFA; adherens junctions; retinal neovascularization; β-catenin

DOI:  https://doi.org/10.1016/j.ajpath.2024.08.005