bims-unfpre 2022-05-01 papers

bims-unfpre

Biomed News

on Unfolded protein response

Issue of 2022–05–01
six papers selected by
Susan Logue, University of Manitoba

Sensor dimer disruption as a new mode of action to block the IRE1-mediated unfolded protein response.
Reducing ER stress with chaperone therapy reverses sleep fragmentation and cognitive decline in aged mice.
METTL3 mediates osteoblast apoptosis by regulating endoplasmic reticulum stress during LPS-induced inflammation.
Targeting DRD2 by the antipsychotic drug, penfluridol, retards growth of renal cell carcinoma via inducing stemness inhibition and autophagy-mediated apoptosis.
The PERKs of mitochondria protection during stress: insights for PERK modulation in neurodegenerative and metabolic diseases.
Emerging roles of endoplasmic reticulum proteostasis in brain development.

Comput Struct Biotechnol J. 2022 ;20 1584-1592

Sensor dimer disruption as a new mode of action to block the IRE1-mediated unfolded protein response.

Kosala N Amarasinghe, Diana Pelizzari-Raymundo, Antonio Carlesso, Eric Chevet, Leif A Eriksson, Sayyed Jalil Mahdizadeh.

  The unfolded protein response (UPR) is activated to cope with an accumulation of improperly folded proteins in the Endoplasmic reticulum (ER). The Inositol requiring enzyme 1α (IRE1α) is the most evolutionary conserved transducer of the UPR. Activated IRE1 forms 'back-to-back'-dimers that enables the unconventional splicing of X-box Binding Protein 1 (XBP1) mRNA. The spliced XBP1 (XBP1s) mRNA is translated into a transcription factor controlling the expression of UPR target genes. Herein, we report a detailed in silico screening specifically targeting for the first time the dimer interface at the IRE1 RNase region. Using the database of FDA approved drugs, we identified four compounds (neomycin, pemetrexed, quercitrin and rutin) that were able to bind to and distort IRE1 RNase cavity. The activity of the compounds on IRE1 phosphorylation was evaluated in HEK293T cells and on IRE1 RNase activity using an in vitro fluorescence assay. These analyzes revealed sub-micromolar IC50 values. The current study reveals a new and unique mode of action to target and block the IRE1-mediated UPR signaling, whereby we may avoid problems associated with selectivity occurring when targeting the IRE1 kinase pocket as well as the inherent reactivity of covalent inhibitors targeting the RNase pocket.

Keywords:  Dimer disruptor; FDA approved drugs; IRE1α; MD simulations; Peptide docking; UPR

DOI:  https://doi.org/10.1016/j.csbj.2022.03.029
Aging Cell. 2022 Apr 30. e13598

Reducing ER stress with chaperone therapy reverses sleep fragmentation and cognitive decline in aged mice.

Jennifer M Hafycz, Ewa Strus, Nirinjini Naidoo.

  As the aging population grows, the need to understand age-related changes in health is vital. Two prominent behavioral changes that occur with age are disrupted sleep and impaired cognition. Sleep disruptions lead to perturbations in proteostasis and endoplasmic reticulum (ER) stress in mice. Further, consolidated sleep and protein synthesis are necessary for memory formation. With age, the molecular mechanisms that relieve cellular stress and ensure proper protein folding become less efficient. It is unclear if a causal relationship links proteostasis, sleep quality, and cognition in aging. Here, we used a mouse model of aging to determine if supplementing chaperone levels reduces ER stress and improves sleep quality and memory. We administered the chemical chaperone 4-phenyl butyrate (PBA) to aged and young mice, and monitored sleep and cognitive behavior. We found that chaperone treatment consolidates sleep and wake, and improves learning in aged mice. These data correlate with reduced ER stress in the cortex and hippocampus of aged mice. Chaperone treatment increased p-CREB, which is involved in memory formation and synaptic plasticity, in hippocampi of chaperone-treated aged mice. Hippocampal overexpression of the endogenous chaperone, binding immunoglobulin protein (BiP), improved cognition, reduced ER stress, and increased p-CREB in aged mice, suggesting that supplementing BiP levels are sufficient to restore some cognitive function. Together, these results indicate that restoring proteostasis improves sleep and cognition in a wild-type mouse model of aging. The implications of these results could have an impact on the development of therapies to improve health span across the aging population.

Keywords:  aging; anti-aging; behavior; molecular biology of aging; mouse models; neuroscience

DOI:  https://doi.org/10.1111/acel.13598
Cell Signal. 2022 Apr 21. pii: S0898-6568(22)00096-1. [Epub ahead of print]95 110335

METTL3 mediates osteoblast apoptosis by regulating endoplasmic reticulum stress during LPS-induced inflammation.

Yiping Kong, Yiwen Zhang, Yongjie Cai, Di Li, Baicheng Yi, Qiong Xu.

  Osteoblast apoptosis is a prominent factor for disrupting skeletal homeostasis in multiple inflammatory bone diseases. METTL3, a key methyltransferase that catalyzes the N6-methyladenosine (m6A) modification of mRNA, has recently been shown to exert a critical role in osteogenic differentiation. However, the function of METTL3 in osteoblast apoptosis under inflammatory conditions remains elusive. In the present study, we observed that the total m6A level and METTL3 expression were upregulated in differentiated osteoblasts and downregulated after LPS stimulation. METTL3 knockdown induced a higher apoptotic rate in LPS-treated osteoblasts. The expression of the antiapoptotic protein BCL-2 decreased, and the apoptotic proteins cleaved Caspase-3, cleaved PARP-1 and cleaved Caspase-12 increased following METTL3 knockdown. Meanwhile, METTL3 silencing inhibited osteoblast proliferation and decreased osteogenic marker expression, ALP activity and mineralized nodules. RNA-seq analysis revealed that differentially expressed genes were significantly enriched in unfolded protein response pathways in METTL3-deficient cells. METTL3 depletion upregulated the expression of the ER stress-related markers, including p-PERK, p-eIF2α, p-IRE1α, GRP78, ATF4, CHOP and ATF6. Inhibition of ER stress by 4-PBA remarkably rescued METTL3 knockdown-induced apoptosis and promoted osteoblast proliferation and differentiation. Mechanistically, METTL3 depletion enhanced the expression and mRNA stability of Grp78, and similar results were observed after YTHDF2 knockdown. RIP-qPCR revealed that YTHDF2 directly interacted with Grp78 mRNA and that the interaction relied on METTL3. Taken together, our study demonstrated that METTL3 knockdown enhanced Grp78 expression through YTHDF2-mediated RNA degradation, which elicited ER stress, thereby promoting osteoblast apoptosis and inhibiting cell proliferation and differentiation under LPS-induced inflammatory condition.

Keywords:  ER stress; METTL3; N6-methyladenosine; apoptosis; mRNA stability; osteoblast differentiation

DOI:  https://doi.org/10.1016/j.cellsig.2022.110335
Cell Death Dis. 2022 Apr 23. 13(4): 400

Targeting DRD2 by the antipsychotic drug, penfluridol, retards growth of renal cell carcinoma via inducing stemness inhibition and autophagy-mediated apoptosis.

Min-Che Tung, Yung-Wei Lin, Wei-Jiunn Lee, Yu-Ching Wen, Yu-Cheng Liu, Ji-Qing Chen, Michael Hsiao, Yi-Chieh Yang, Ming-Hsien Chien.

Renal cell carcinoma (RCC) is one of the most lethal genitourinary malignancies with poor prognoses, since it is largely resistant to chemotherapy, radiotherapy, and targeted therapy. The persistence of cancer stem cells (CSCs) is the major cause of treatment failure with RCC. Recent evidence showed that dopamine receptor D2 (DRD2)-targeting antipsychotic drugs such as penfluridol exert oncostatic effects on several cancer types, but the effect of penfluridol on RCC remains unknown. Here, we uncovered penfluridol suppressed in vitro cell growth and in vivo tumorigenicity of various RCC cell lines (Caki-1, 786-O, A498, and ACHN) and enhanced the Sutent (sunitinib)-triggered growth inhibition on clear cell (cc)RCC cell lines. Mechanistically, upregulation of endoplasmic reticulum (ER) stress-induced unfolded protein response (UPR) was critical for autophagy-mediated apoptosis induced by penfluridol. Transcriptional inhibition of OCT4 and Nanog via inhibiting GLI1 was important for penfluridol-induced stemness and proliferation inhibition. The anticancer activities of penfluridol on ccRCC partially occurred through DRD2. In clinical ccRCC specimens, positive correlations of DRD2 with GLI1, OCT4, and Nanog were observed and their expressions were correlated with worse prognoses. Summarizing, DRD2 antagonists such as penfluridol induce UPR signaling and suppress the GLI1/OCT4/Nanog axis in ccRCC cells to reduce their growth through inducing autophagy-mediated apoptosis and stemness inhibition. These drugs can be repurposed as potential agents to treat ccRCC patients.

DOI: https://doi.org/10.1038/s41419-022-04828-3
Biol Rev Camb Philos Soc. 2022 Apr 26.

The PERKs of mitochondria protection during stress: insights for PERK modulation in neurodegenerative and metabolic diseases.

Liliana M Almeida, Brígida R Pinho, Michael R Duchen, Jorge M A Oliveira.

  Protein kinase RNA-like ER kinase (PERK) is an endoplasmic reticulum (ER) stress sensor that responds to the accumulation of misfolded proteins. Once activated, PERK initiates signalling pathways that halt general protein production, increase the efficiency of ER quality control, and maintain redox homeostasis. PERK activation also protects mitochondrial homeostasis during stress. The location of PERK at the contact sites between the ER and the mitochondria creates a PERK-mitochondria axis that allows PERK to detect stress in both organelles, adapt their functions and prevent apoptosis. During ER stress, PERK activation triggers mitochondrial hyperfusion, preventing premature apoptotic fragmentation of the mitochondria. PERK activation also increases the formation of mitochondrial cristae and the assembly of respiratory supercomplexes, enhancing cellular ATP-generating capacity. PERK strengthens mitochondrial quality control during stress by promoting the expression of mitochondrial chaperones and proteases and by increasing mitochondrial biogenesis and mitophagy, resulting in renewal of the mitochondrial network. But how does PERK mediate all these changes in mitochondrial homeostasis? In addition to the classic PERK-eukaryotic translation initiation factor 2α (eIF2α)-activating transcription factor 4 (ATF4) pathway, PERK can activate other protective pathways - PERK-O-linked N-acetyl-glucosamine transferase (OGT), PERK-transcription factor EB (TFEB), and PERK-nuclear factor erythroid 2-related factor 2 (NRF2) - contributing to broader regulation of mitochondrial dynamics, metabolism, and quality control. The pharmacological activation of PERK is protective in models of neurodegenerative and metabolic diseases, such as Huntington's disease, progressive supranuclear palsy and obesity, while the inhibition of PERK was protective in models of Parkinson's and prion diseases and diabetes. In this review, we address the molecular mechanisms by which PERK regulates mitochondrial dynamics, metabolism and quality control, and discuss the therapeutic potential of targeting PERK in neurodegenerative and metabolic diseases.

Keywords:  PERK; dynamics; endoplasmic reticulum; metabolic diseases; metabolism; mitochondria; neurodegeneration; stress; unfolded protein response

DOI:  https://doi.org/10.1111/brv.12860
Cells Dev. 2022 Apr 25. pii: S2667-2901(22)00017-1. [Epub ahead of print] 203781

Emerging roles of endoplasmic reticulum proteostasis in brain development.

Giselle Espinosa Vásquez, Danilo B Medinas, Hery Urra, Claudio Hetz.

  The development of the central nervous system requires a series of morphogenetic events that shape brain and spinal cord structures. Several brain regions and neural circuits are formed by differential gene expression patterns and cell migration events involving neurons. During neurogenesis and neuritogenesis, increased demand for protein synthesis occurs to express key neuronal proteins to generate axons, dendrites, and active synapsis. The endoplasmic reticulum (ER) is a central hub controlling protein homeostasis (proteostasis), impacting a wide range of cellular processes required for brain function. Although most of the field has focused on ER stress in neurodegenerative diseases marked by abnormal protein aggregation, accumulating evidence indicates that ER proteostasis contributes to brain development impacting processes such as neuronal migration, differentiation, and function. Here, we review emerging evidence linking neurodevelopment with ER proteostasis and its relevance to human disorders.

Keywords:  Brain development; Chaperones; Endoplasmic reticulum; Neurodevelopmental disorders; Proteostasis; Unfolded protein response

DOI:  https://doi.org/10.1016/j.cdev.2022.203781