bims-unfpre 2024-07-21 papers

bims-unfpre

Biomed News

on Unfolded protein response

Issue of 2024–07–21
eight papers selected by
Susan Logue, University of Manitoba

Inhibition of PERK mediated UPR acts as a switch for reversal of residual senescence and as senolytic therapy in glioblastoma.
Reduced Expression of Oligodendrocyte Linage-Enriched Transcripts During the Endoplasmic Reticulum Stress/Integrated Stress Response.
The unfolded protein response machinery in glioblastoma genesis, chemoresistance and as a druggable target.
The role of ER exit sites in maintaining P-body organization and transmitting ER stress response during Drosophila melanogaster oogenesis.
Dysregulation of Ceramide Metabolism Causes Phytoceramide-Dependent Induction of the Unfolded Protein Response.
ZDHHC9-mediated Bip/GRP78 S-palmitoylation inhibits unfolded protein response and promotes bladder cancer progression.
Diverse effects of synthetic glucocorticoid species on cell viability and stress response of neuroblastoma cells.
Activation of the PERK/eIF2α axis is a pivotal prerequisite of taxanes to cancer cell apoptosis and renders synergism to overcome paclitaxel resistance in breast cancer cells.

Neuro Oncol. 2024 Jul 18. pii: noae134. [Epub ahead of print]

Inhibition of PERK mediated UPR acts as a switch for reversal of residual senescence and as senolytic therapy in glioblastoma.

Madhura Ketkar, Sanket Desai, Pranav Rana, Rahul Thorat, Sridhar Epari, Amit Dutt, Shilpee Dutt.

   BACKGROUND: Glioblastoma due to recurrence is clinically challenging with 10-15months overall survival. Previously we showed therapy induced senescence (TIS) in glioblastoma reverses causing recurrence. Here, we aim to delineate TIS reversal mechanism for potential therapeutic intervention to prevent GBM recurrence.
METHODS: Residual senescent (RS) and End of Residual Senescence (ERS) cells were captured from GBM patient-derived primary-cultures and cell lines mimicking clinical scenario. RNA-sequencing, transcript/protein validations, knock-down/inhibitor studies, ChIP RT-PCR, biochemical assays and IHCs were performed for mechanistics of TIS reversal. In vivo validations were conducted in GBM orthotopic mouse model.
RESULTS: Transcriptome analysis showed co-expression of ER stress-UPR and senescence associated secretory phenotype (SASP) with TIS induction and reversal. Robust SASP production and secretion by RS cells could induce senescence, ROS, DNA damage and ER stress in paracrine fashion independent of radiation. Neutralization of most significantly enriched cytokine from RS-secretome IL1β, suppressed SASP and delayed senescence reversal. Mechanistically, with SASP and massive protein accumulation in Endoplasmic reticulum, RS cells displayed stressed ER morphology, upregulated ER stress markers and PERK pathway activation via peIF2α-ATF4-CHOP which was spontaneously resolved in ERS. ChIP RT-PCR showed CHOP occupancy at CXCL8/IL8, CDKN1A/p21 and BCL2L1/BCLXL aiding survival. PERK knockdown/inhibition with GSK2606414 in combination with radiation led to sustained ER stress and senescence without SASP. PERKi in RS functioned as senolytic via apoptosis and prevented recurrence in vitro and in vivo ameliorating overall survival.
CONCLUSION: We demonstrate that PERK mediated UPR regulates senescence reversal and its inhibition can be exploited as potential seno-therapeutic option in glioblastoma.

Keywords:  ER stress; Glioblastoma; PERK; TIS reversal; Unfolded protein response

DOI:  https://doi.org/10.1093/neuonc/noae134
ASN Neuro. 2024 ;16(1): 2371162

Reduced Expression of Oligodendrocyte Linage-Enriched Transcripts During the Endoplasmic Reticulum Stress/Integrated Stress Response.

Yonglin Gao, Lukasz P Slomnicki, Ewa Kilanczyk, Michael D Forston, Maciej Pietrzak, Eric C Rouchka, Russell M Howard, Scott R Whittemore, Michal Hetman.

  Endoplasmic reticulum (ER) stress in oligodendrocyte (OL) linage cells contributes to several CNS pathologies including traumatic spinal cord injury (SCI) and multiple sclerosis. Therefore, primary rat OL precursor cell (OPC) transcriptomes were analyzed using RNASeq after treatments with two ER stress-inducing drugs, thapsigargin (TG) or tunicamycin (TM). Gene ontology term (GO) enrichment showed that both drugs upregulated mRNAs associated with the general stress response. The GOs related to ER stress were only enriched for TM-upregulated mRNAs, suggesting greater ER stress selectivity of TM. Both TG and TM downregulated cell cycle/cell proliferation-associated transcripts, indicating the anti-proliferative effects of ER stress. Interestingly, many OL lineage-enriched mRNAs were downregulated, including those for transcription factors that drive OL identity such as Olig2. Moreover, ER stress-associated decreases of OL-specific gene expression were found in mature OLs from mouse models of white matter pathologies including contusive SCI, toxin-induced demyelination, and Alzheimer's disease-like neurodegeneration. Taken together, the disrupted transcriptomic fingerprint of OL lineage cells may facilitate myelin degeneration and/or dysfunction when pathological ER stress persists in OL lineage cells.

Keywords:  Differentiation; endoplasmic reticulum stress; integrated stress response; myelination; oligodendrocyte precursor cells; transcriptome; white matter injury

DOI:  https://doi.org/10.1080/17590914.2024.2371162
CNS Neurosci Ther. 2024 Jul;30(7): e14839

The unfolded protein response machinery in glioblastoma genesis, chemoresistance and as a druggable target.

Lucette Z Simbilyabo, Liting Yang, Jie Wen, Zhixiong Liu.

   BACKGROUND: The role of the unfolded protein response (UPR) has been progressively unveiled over the last decade and several studies have investigated its implication in glioblastoma (GB) development. The UPR restores cellular homeostasis by triggering the folding and clearance of accumulated misfolded proteins in the ER consecutive to endoplasmic reticulum stress. In case it is overwhelmed, it induces apoptotic cell death. Thus, holding a critical role in cell fate decisions.
METHODS: This article, reviews how the UPR is implicated in cell homeostasis maintenance, then surveils the evidence supporting the UPR involvement in GB genesis, progression, angiogenesis, GB stem cell biology, tumor microenvironment modulation, extracellular matrix remodeling, cell fate decision, invasiveness, and grading. Next, it concurs the evidence showing how the UPR mediates GB chemoresistance-related mechanisms.
RESULTS: The UPR stress sensors IRE1, PERK, and ATF6 with their regulator GRP78 are upregulated in GB compared to lower grade gliomas and normal brain tissue. They are activated in response to oncogenes and are implicated at different stages of GB progression, from its genesis to chemoresistance and relapse. The UPR arms can be effectors of apoptosis as mediators or targets.
CONCLUSION: Recent research has established the role of the UPR in GB pathophysiology and chemoresistance. Targeting its different sensors have shown promising in overcoming GB chomo- and radioresistance and inducing apoptosis.

Keywords:  chemoresistance; glioblastoma; glioblastoma resistance; glioblastoma stem cell; temozolomide; unfolded protein response

DOI:  https://doi.org/10.1111/cns.14839
bioRxiv. 2024 Jul 05. pii: 2024.07.03.601952. [Epub ahead of print]

The role of ER exit sites in maintaining P-body organization and transmitting ER stress response during Drosophila melanogaster oogenesis.

Samantha N Milano, Livia V Bayer, Julie J Ko, Caroline E Casella, Diana P Bratu.

Processing bodies (P-bodies) are cytoplasmic membrane-less organelles which host multiple mRNA processing events. While the fundamental principles of P-body organization are beginning to be elucidated in vitro , a nuanced understanding of how their assembly is regulated in vivo remains elusive. Here, we investigate the potential link between ER exit sites and P-bodies in Drosophila melanogaster egg chambers. Employing a combination of live and super-resolution imaging, we found that P-bodies associated with ER exit sites are larger and less mobile than cytoplasmic P-bodies, indicating that they constitute a distinct class of P-bodies which are more mature than their cytoplasmic counterparts. Moreover, we demonstrate that altering the composition of ER exit sites has differential effects on core P-body proteins (Me31B, Cup, and Trailer Hitch) suggesting a potential role for ER exit sites in P-body organization. We further show that in the absence of ER exit sites, P-body integrity is compromised and the stability and translational repression efficiency of the maternal mRNA, oskar , are reduced. Finally, we show that ER stress is communicated to P-bodies via ER exit sites, highlighting the pivotal role of ER exit sites as a bridge between membrane-bound and membrane-less organelles in ER stress response. Together, our data unveils the significance of ER exit sites not only in governing P-body organization, but also in facilitating inter-organellar communication during stress, potentially bearing implications for a variety of disease pathologies.

DOI: https://doi.org/10.1101/2024.07.03.601952
Mol Biol Cell. 2024 Jul 18. mbcE24030121

Dysregulation of Ceramide Metabolism Causes Phytoceramide-Dependent Induction of the Unfolded Protein Response.

Tamayanthi Rajakumar, Md Amin Hossain, Sylwia A Stopka, Yagmur Micoogullari, Jessie Ang, Nathalie Y R Agar, John Hanna.

The unfolded protein response (UPR) detects and mitigates the harmful effects of dysregulated endoplasmic reticulum (ER) function. The UPR has been best characterized as a protein quality control response, and the sole UPR sensor in yeast, Ire1, is known to detect misfolded ER proteins. However, recent work suggests the UPR can also sense diverse defects within the ER membrane, including increased fatty acid saturation and altered phospholipid abundance. These and other lipid-related stimuli have been referred to as lipid bilayer stress, and may be sensed independently through Ire1's transmembrane domain. Here we show that loss of Isc1, a phospholipase that catabolizes complex ceramides, causes UPR induction, even in the absence of exogenous stress. A series of chemical and genetic approaches identified a requirement for very long chain fatty acid (VLCFA)-containing phytoceramides for UPR induction. In parallel, comprehensive lipidomics analyses identified large increases in abundance of specific VLCFA-containing phytoceramides in the isc1Δ mutant. We failed to identify evidence of an accompanying defect in protein quality control or ER-associated protein degradation. These results extend our understanding of lipid bilayer stress in the UPR, and provide a foundation for mechanistic investigation of this fascinating intersection between ceramide metabolism, membrane homeostasis, and the UPR.

DOI: https://doi.org/10.1091/mbc.E24-03-0121
Cancer Lett. 2024 Jul 18. pii: S0304-3835(24)00513-5. [Epub ahead of print]598 217118

ZDHHC9-mediated Bip/GRP78 S-palmitoylation inhibits unfolded protein response and promotes bladder cancer progression.

Weiquan Li, Jingchong Liu, Tiexi Yu, Feiyi Lu, Qi Miao, Xiangui Meng, Wen Xiao, Hongmei Yang, Xiaoping Zhang.

  Recent studies have highlighted palmitoylation, a novel protein post-translational modification, as a key player in various signaling pathways that contribute to tumorigenesis and drug resistance. Despite this, its role in bladder cancer (BCa) development remains inadequately understood. In this study, ZDHHC9 emerged as a significantly upregulated oncogene in BCa. Functionally, ZDHHC9 knockdown markedly inhibited tumor proliferation, promoted tumor cell apoptosis, and enhanced the efficacy of gemcitabine (GEM) and cisplatin (CDDP). Mechanistically, SP1 was found to transcriptionally activate ZDHHC9 expression. ZDHHC9 subsequently bound to and palmitoylated the Bip protein at cysteine 420 (Cys420), thereby inhibiting the unfolded protein response (UPR). This palmitoylation at Cys420 enhanced Bip's protein stability and preserved its localization within the endoplasmic reticulum (ER). ZDHHC9 might become a novel therapeutic target for BCa and could also contribute to combination therapy with GEM and CDDP.

Keywords:  Bladder cancer; Palmitoylation; Unfolded protein response; ZDHHC9

DOI:  https://doi.org/10.1016/j.canlet.2024.217118
Neuroscience. 2024 Jul 14. pii: S0306-4522(24)00315-4. [Epub ahead of print]554 1-10

Diverse effects of synthetic glucocorticoid species on cell viability and stress response of neuroblastoma cells.

Lucrezia Zerillo, Immacolata Polvere, Romania Stilo, Pasquale Vito, Michele Rinaldi, Tiziana Zotti, Ciro Costagliola.

  Glucocorticoids (GCs) are widely used as powerful anti-inflammatory and immunosuppressive therapeutics in multiple pathological conditions. However, compelling evidence indicates that they might promote neurodegeneration by altering mitochondrial homeostatic processes. Although the effect of dexamethasone on cell survival and homeostasis has been widely investigated, the effect of other glucocorticoids needs to be explored in more detail. In this report, we have compared the neurotoxicity induced by dexamethasone, prednisolone, betamethasone, and hydrocortisone in cultured neuroblastoma cells, through the analysis of several parameters such as cell viability, ER stress, oxidative stress, and mitochondrial fusion and fission markers. Interestingly, we have found that synthetic glucocorticoids may impact neuronal viability by affecting different cellular responses, suggesting that their therapeutic use should be consciously decided after careful consideration of benefits and detrimental effects.

Keywords:  Glucocorticoids; Mitochondrial dysfunction; Neurotoxicity; Stress response

DOI:  https://doi.org/10.1016/j.neuroscience.2024.07.010
Cancer Cell Int. 2024 Jul 17. 24(1): 249

Activation of the PERK/eIF2α axis is a pivotal prerequisite of taxanes to cancer cell apoptosis and renders synergism to overcome paclitaxel resistance in breast cancer cells.

Wanhua Cai, Dade Rong, Jiayu Ding, Xiaomei Zhang, Yuwei Wang, Ying Fang, Jing Xiao, Shulan Yang, Haihe Wang.

   BACKGROUND: Microtubule polymerization is usually considered as the upstream of apoptotic cell death induced by taxanes, but recently published studies provide more insights into the mechanisms responsible for the antineoplastic effect of taxanes. In this study, we figure out the role of the stress-related PERK/eIF2α axis in tumor cell death upon taxane treatment along with paclitaxel resistance.
METHODS: Utilizing immunoblot assay, the activation status of PERK-eIF2α signaling was detected in a panel of cancer cell lines after the treatment of taxanes. The causal role of PERK-eIF2α signaling in the cancer cell apoptosis induced by taxanes was examined via pharmacological and genetic inhibitions of PERK. The relationship between microtubule polymerization and PERK-eIF2α activation was explored by immunofluorescent and immunoblotting assays. Eventaually, the combined therapeutic effect of paclitaxel (PTX) and CCT020312, a PERK agonist, was investigated in PTX-resistant breast cancer cells in vitro and in vivo.
RESULTS: PERK-eIF2α axis was dramatically activated by taxanes in several cancer cell types. Pharmacological or genetic inhibition of PERK efficiently impaired taxane-induced apoptotic cell death, independent of the cellular microtubule polymerization status. Moreover, PTX was able to activate the PERK/eIF2α axis in a very low concentration without triggering microtubule polymerization. In PTX-resistant breast cancer cells, the PERK/eIF2α axis was attenuated in comparison with the PTX-sensitive counterparts. Reactivation of the PERK/eIF2α axis in the PTX-resistant breast cancer cells with PERK agonist sensitized them to PTX in vitro. Combination treatment of the xenografted PTX-resistant breast tumors with PERK agonist and PTX validated the synergic effect of PTX and PERK activation in vivo.
CONCLUSION: Activation of the PERK/eIF2α axis is a pivotal prerequisite of taxanes to initiate cancer cell apoptosis, which is independent of the well-known microtubule polymerization-dependent manner. Simultaneous activation of PERK-eIF2α signaling would be a promising therapeutic strategy to overcome PTX resistance in breast cancer or other cancers.

Keywords:  Breast cancer; ER stress; PERK/eIF2α; Taxane; Tumor drug resistance

DOI:  https://doi.org/10.1186/s12935-024-03443-w