Project description:The Akita mutation (C96Y) in the insulin gene results in early onset diabetes in both humans and mice. Expression of the mutant proinsulin (C96Y) causes endoplasmic reticulum (ER) stress in pancreatic ?-cells and consequently the cell activates the unfolded protein response (UPR). Since the proinsulin is terminally misfolded however, the ER stress is irremediable and chronic activation of the UPR eventually activates apoptosis in the cell population. We used microarray gene expression arrays to analyze the IRE1-dependent activation of genes in response to misfolded proinsulin expression in an inducible mutant proinsulin (C96Y) insulinoma cell line by inhibiting the IRE1 endoribonucleas activity with a specific inhibitor, 4u8c. Insulinoma cells with doxycycline inducible C96Y-proinsulin expression were either untreated, treated with doxycycline alone or treated with dox and 4u8c. This was done with two biological replicates.
Project description:The Akita mutation (C96Y) in the insulin gene results in early onset diabetes in both humans and mice. Expression of the mutant proinsulin (C96Y) causes endoplasmic reticulum (ER) stress in pancreatic -cells and consequently the cell activates the unfolded protein response (UPR). Since the proinsulin is terminally misfolded however, the ER stress is irremediable and chronic activation of the UPR eventually activates apoptosis in the cell population. We used microarray gene expression arrays to analyze the IRE1-dependent activation of genes in response to misfolded proinsulin expression in an inducible mutant proinsulin (C96Y) insulinoma cell line by inhibiting the IRE1 endoribonucleas activity with a specific inhibitor, 4u8c.
Project description:Lipoic acid induced endoplasmic reticulum stress-mediated apoptosis in rat hepatoma cells:identification of new ER stress aggravator (ERSA)
Project description:The accumulation of misfolded proteins in the endoplasmic reticulum (ER) induces the unfolded protein response (UPR), which acts through various mechanisms to reduce ER stress. We previously found ER stress induced by tunicamycin (TM) treatment promotes the activation of small GTPase Arl1 and thereby increasing the recruitment of downstream effector golgin Imh1 to the late-Golgi. However, the role of Imh1 under ER stress remains unknown. In this study, we found Imh1 is required for the recycling of two SNAREs, Snc1 and Tlg1, upon TM-induced ER stress and phosphorylation of Imh1 is required for this regulation. Since Ire1 is the sensor of UPR in yeast and we previous found that Ire1 is required for Arl1-Imh1 activation, we wonder whether Ire1 signaling is also responsible for the TM-induced phosphorylation of Imh1 and the subsequent SNARE transport. We compared the phosphorylation signal of Imh1 in WT with that in the absence of Ire1 and further performed SILAC method in a label swap replication. Collectively, this study illustrates the mechanism of how signaling under ER stress promotes Imh1 in cooperation with another tether factor in regulating the SNARE transport to alleviate ER stress in yeast cells.
Project description:The Unfolded Protein Response (UPR) is an adaptive pathway that restores cellular homeostasis after endoplasmic reticulum (ER) stress caused by an impairment of its protein folding capacity. The ER-resident kinase/ribonuclease Ire1 is the only UPR sensor that has been conserved during evolution from yeast to mammals; in these organisms, Ire1 transmits information from the ER to the nucleus trough the non-conventional splicing of Hac1 (yeast)/Xbp1 (metazoans) mRNA. We described the Dictyostelium discoideum ER-stress response and characterized its single bonafide Ire1 orthologue, IreA. We found that tunicamycin (TN) triggers a gene-expression program that increases the protein folding capacity of the ER and that alleviates ER protein load. Further, IreA resulted essential not only for cell-survival after TN-induced ER-stress, but also to accomplish about nearly 40% of the transcriptional changes induced upon a TN treatment. In addition, we described that autophagy is activated in Dictyostelium cells after a TN treatment and that autophagy-defective mutants exhibited increased sensitivity to this drug. The response of Dictyostelium cells to ER-stress involves the combined activation of an IreA-dependent gene expression program and the autophagy pathway.
Project description:In order to establish a rat embryonic stem cell transcriptome, mRNA from rESC cell line DAc8, the first male germline competent rat ESC line to be described and the first to be used to generate a knockout rat model was characterized using RNA sequencing (RNA-seq) analysis.
Project description:Fragile X Mental Retardation protein (FMRP), widely known for its role in hereditary intellectual disability, is an RNA-binding protein (RBP) that controls translation of select mRNAs. We discovered that endoplasmic reticulum (ER) stress induces phosphorylation of FMRP on a site that is known to enhance translation inhibition of FMRP-bound mRNAs. We show ER stress-induced activation of Inositol requiring enzyme-1 (IRE1), an ER-resident stress-sensing kinase/endoribonuclease, leads to FMRP phosphorylation and to suppression of macrophage cholesterol efflux and apoptotic cell clearance (efferocytosis). Conversely, FMRP-deficiency and pharmacological inhibition of IRE1 kinase activity enhances cholesterol efflux and efferocytosis, reducing atherosclerosis in mice. Our results provide mechanistic insights into how ER stress-induced IRE1 kinase activity contributes to macrophage cholesterol homeostasis and suggest IRE1 inhibition as a promising new way to counteract atherosclerosis.