Project description:BRCA1-associated protein 1 (BAP1) is a tumor suppressor and its loss can result in mesothelioma, uveal and cutaneous melanoma, clear cell renal cell carcinoma and bladder cancer. BAP1 is a deubiquitinating enzyme of the UCH class that has been implicated in various cellular processes like cell growth, cell cycle progression, ferroptosis and ER metabolic stress response. Here, we identify novel BAP1 interacting proteins in the cytoplasm by expressing GFP-tagged BAP1 in an endogenous BAP1 deficient cell line using affinity purification followed by mass spec (AP-MS) analysis. Among these novel interacting proteins are all subunits of the heptameric coat protein complex I (COPI) that is involved in vesicle formation and protein cargo binding and sorting.
Project description:Compared to the well-established roles of apoptosis in tumor suppression, the roles and regulatory mechanisms of ferroptosis, a non-apoptotic form of cell death, in tumor biology remain much less understood. BRCA1-associated protein 1 (BAP1) encodes a nuclear de-ubiquitinating (DUB) enzyme to reduce histone 2A ubiquitination (H2Aub) on chromatin, and is a tumor suppressor in several human cancers. Here, integrated transcriptomic, epigenomic, and cancer genomic analyses link BAP1 to metabolism-related biological processes, including oxidative stress response, and identify cystine transporter SLC7A11 as a BAP1-repressed target gene with high relevance to BAP1-mediated tumor suppression in human cancers. Functional studies reveal that BAP1, in a DUB-dependent manner, decreases H2Aub occupancy on the SLC7A11 promoter and represses SLC7A11 expression, and that BAP1 inhibits cystine uptake and promotes ferroptosis through repressing SLC7A11 expression. Finally, we show that BAP1 inhibits tumor development partly through SLC7A11, and that cancer-associated BAP1 mutants lose their abilities to repress SLC7A11 and to promote ferroptosis. Together, the results of our study show that BAP1 executes its tumor suppression function at least partly through its regulation of SLC7A11 and ferroptosis, and uncover a previously unappreciated mechanism coupling ferroptosis to tumor suppression.
Project description:Endoplasmic reticulum (ER) stress occurs when misfolded proteins accumulate in the ER. The cellular response to ER stress involves complex transcriptional and translational changes, important to the survival of the cell. ER stress is a primary cause and a modifier of many human diseases. A first step to understanding how the ER stress response impacts human disease is to determine how the transcriptional response to ER stress varies among individuals. The genetic diversity of the eight mouse Collaborative Cross (CC) founder strains allowed us to determine how genetic variation impacts the ER stress transcriptional response. We used tunicamycin, a drug commonly used to induce ER stress, to elicit an ER stress response in mouse embryonic fibroblasts (MEFs) derived from the CC founder strains and measured their transcriptional responses. We identified hundreds of genes that differed in response to ER stress across these genetically diverse strains. Strikingly, inflammatory response genes differed most between strains; major canonical ER stress response genes showed relatively invariant responses across strains. To uncover the genetic architecture underlying these strain differences in ER stress response, we measured the transcriptional response to ER stress in MEFs derived from a subset of F1 crosses between the CC founder strains. We found a unique layer of regulatory variation that is only detectable under ER stress conditions. Over 80% of the regulatory variation under ER stress derives from cis-regulatory differences. This is the first study to characterize the genetic variation in ER stress transcriptional response in the laboratory mouse. Our findings indicate that the ER stress transcriptional response is highly variable among strains and arises from genetic variation in individual downstream response genes, rather than major signaling transcription factors. These results have important implications for understanding how genetic variation impacts the ER stress response, an important component of many human diseases.
Project description:Endoplasmic reticulum (ER) stress occurs when misfolded proteins accumulate in the ER. The cellular response to ER stress involves complex transcriptional and translational changes, important to the survival of the cell. ER stress is a primary cause and a modifier of many human diseases. A first step to understanding how the ER stress response impacts human disease is to determine how the transcriptional response to ER stress varies among individuals. The genetic diversity of the eight mouse Collaborative Cross (CC) founder strains allowed us to determine how genetic variation impacts the ER stress transcriptional response. We used tunicamycin, a drug commonly used to induce ER stress, to elicit an ER stress response in mouse embryonic fibroblasts (MEFs) derived from the CC founder strains and measured their transcriptional responses. We identified hundreds of genes that differed in response to ER stress across these genetically diverse strains. Strikingly, inflammatory response genes differed most between strains; major canonical ER stress response genes showed relatively invariant responses across strains. To uncover the genetic architecture underlying these strain differences in ER stress response, we measured the transcriptional response to ER stress in MEFs derived from a subset of F1 crosses between the CC founder strains. We found a unique layer of regulatory variation that is only detectable under ER stress conditions. Over 80% of the regulatory variation under ER stress derives from cis-regulatory differences. This is the first study to characterize the genetic variation in ER stress transcriptional response in the laboratory mouse. Our findings indicate that the ER stress transcriptional response is highly variable among strains and arises from genetic variation in individual downstream response genes, rather than major signaling transcription factors. These results have important implications for understanding how genetic variation impacts the ER stress response, an important component of many human diseases. We investigated the genetic variation in ER stress transcriptional response in mouse embryonic fibroblasts (MEFs) across eight mouse strains: A/J, C57BL/6J, 129S1Sv/ImJ, NOD/ShiLtJ, NZO/H1LtJ, CAST/EiJ, PWK/PhJ, and WSB/EiJ. MEFs from each strain were treated with a control DMSO or ER stress-inducing drug, Tunicamycin (TM). To identify the genetic architecture underlying this genetic variation, MEFs from F1 strains were also studied. MEFs from the following F1s were evaluated: C57BL/6J X CAST/EiJ, C57BL/6J X 129S1Sv/ImJ, C57BL/6J X NOD/ShiLtJ, C57BL/6J X NZO/H1LtJ, and C57BL/6J X WSB/EiJ. Again F1 MEFS were treated with either DMSO or TM. There are two or three replicates for each sample.
Project description:Integrated Stress Response (ISR) is a homeostatic mechanism induced by endoplasmic reticulum (ER) stress. With acute/transient ER stress, decreased global protein synthesis and increased uORF mRNA translation are followed by translation normalization. Here, we report a dramatically different response during more physiologically relevant chronic ER stress. This unique ISR program is characterized by persistently elevated uORF mRNA translation and concurrent gene expression reprogramming, which permits simultaneous stress sensing and proteostasis. PERK-dependent switching from eIF4F/eIF2B- to eIF3D/GADD34-regulated translation initiation results in partial but not complete translation recovery, and together with transcriptional reprogramming, selectively bolsters expression of proteins with ER functions. Coordination of these transcriptional and translational changes prevents ER dysfunction and inhibits “foamy cell” development, thus establishing a molecular basis for understanding human diseases associated with ER dysfunction.
Project description:With the intensification of global warming, rainbow trout is suffering from varying degrees thermal stimulation, heat stress may cause pathological signs or diseases by reducing the immune roles and then lead to mass mortality, so high temperatures severely restrict the development of its aquaculture. Understanding the molecular regulation mechanism of rainbow trout under heat stress is used to take measures to relieve symptoms. We performed multiple transcriptomic analysis of liver tissues from rainbow trout under heat stress (24 °C) and control conditions (18 °C) to identify circRNAs, miRNAs and mRNAs. Changes of non-specific immune parameters revealed that strong stress response of rainbow trout is caused in 24 °C. A total of 324 DEcircRNAs, 105 DEmiRNAs, and 1885 DEmRNAs were identified from six libraries, and ceRNA regulatory network is constructed. 301 circRNA–miRNA and 51 miRNA–mRNA negative correlation pairs were screened from ceRNA regulatory network, and predicted three regulatory correlation pairs that novel_circ_003889 - novel-m0674-3p - hsp90ab1, novel_circ_002325 - miR-18-y - HSPA13 and novel_circ_002446 - novel-m0556-3p - hsp70. Some genes involved in metabolic process, biological regulation or response to stimulus are highly induced at high temperatures. Several important pathways involved in heat stress were characterized, such as Protein processing in endoplasmic reticulum (ER), Estrogen signaling pathway, HIF-1 signaling pathway, etc. These results extend our understanding of the molecular mechanisms of heat stress response and expected to provide a novel insight into develop strategies for relieve heat stress.
Project description:Endoplasmic reticulum (ER) stress triggers an adaptive response which fosters tumor cell survival and resilience to stress conditions. Activation of the endoplasmic reticulum stress response, through its PERK branch, promotes the phosphorylation of the α-subunit of translation initiation factor eIF2alpha, thereby repressing general protein translation and selectively augmenting the translation of ATF4 with the downstream CHOP transcription factor and the protein disulfide oxidase ERO1. Here, we show that ISRIB, a small molecule, which inhibits the action of the phosphorylated α-subunit of eIF2, thereby activating protein translation, synergistically interacts with the genetic deficiency of protein disulfide oxidase ERO1 enfeebling tumor growth and spreading. ISRIB represses CHOP signal but surprisingly does not inhibit ERO1. Mechanistically, ISRIB increases the ER protein load with a prominent perturbing effect on ERO1 deficient Triple-Negative breast cells, which have adapted to live with low client protein load, while ERO1 deficiency selectively impairs VEGF-dependent angiogenesis. Strikingly, ERO1-deficient Triple Negative Breast Cancer xenografts have augmented ER stress response and PERK branch. In vivo, ISRIB synergistically with ERO1 deficiency inhibits the growth of Triple-Negative Breast cancer xenografts by impairing proliferation and angiogenesis, while it is not effective on the xenograft counterparts with ERO1. In summary, these results demonstrate that ISRIB together with ERO1 deficiency synergistically shatters a feature of the adaptive ER stress response while ERO1 deficiency selectively impairs angiogenesis in tumors, thereby together promoting tumor cytotoxicity. Therefore, our findings suggest two surprising findings in breast tumors: ERO1 is not regulated via CHOP and ISRIB represents a therapeutic option to efficiently inhibit tumor progression in those tumors with limited ERO1 and high PERK.
Project description:Metabolic diseases are strongly associated with endoplasmic reticulum (ER) stress. Upon ER stress, the unfolded protein response (UPR) is activated to limit cellular damage. However, escalating cellular UPR response weakens with age. Here, we show that 5-day-old Caenorhabditis elegans fed a bacteria diet with 2% glucose (high glucose diet, HGD-5) extend their lifespan while shortening the lifespan of 1-day-old (HGD-1) animals. We observed a metabolic shift in HGD-1 as glucose and fertility synergistically prolonged the lifespan of HGD-5, independently of DAF-16. Notably, we identified that UPR stress sensors ATF-6 and PEK-1 extended the longevity of HGD-5 worms, while the ire-1 ablation drastically increased HGD-1 lifespan. Based on these observations, we postulate that HGD activates the otherwise quiescent UPR in aged worms to overcome ageing-related stress and restore ER homeostasis. In contrast, young animals subjected to HGD provokes unresolved ER stress, conversely leading to a detrimental stress response.