Project description:Perturbation of tissue homeostasis accompanies a diversity of inflammatory pathologies and imposes metabolic constraints at the cellular level that elicit ER stress, protein misfolding, and cell death. In response to ER stress, cells initiate the unfolded protein response (UPR), which determines divergent cell fate decisions, either promoting recovery of ER proteostasis and cell survival or triggering programmed cell death. However, the mechanisms by which the UPR transitions from the adaptive to terminal state are not fully understood. To discover novel UPR pathway regulators that influence the outcome of cellular ER stress responses, we performed genome-scale genetic perturbations. Our genome-wide screens revealed that distinct sets of genes regulate UPR activity and maintenance of ER homeostasis. This expansive dataset provides a rich resource that can be leveraged to elucidate signaling crosstalk during ER stress and discover novel UPR regulators.
Project description:We are currently studying how these information-carrying oligosaccharides are involved in cellular stress responses, particularly in human genetic diseases called Congenital Disorders Of Glycosylation in which oligosaccharide assembly is defective. We are interested in endoplasmic stress responses/unfolded protein responses. ER glycans and ER lectins are intimately involved in the folding of ER proteins. Therefore, ER lectins and ER glycosyltransferases may be controlled by these stress responses, to produce and/or recognize key glycans in the stress response. Our model system is the human dermal fibroblast. We have successfully calibrated the ER stress responses in these cells by determining the magnitudes of various stress effects (such as chaperone transcription) with different forms of ER stress. We are also completing a study in which activation the signaling molecules Ire1 and ATF6 are also calibrated. We prepared multiple identical aliquots of RNA from cells stressed under several of these calibrated conditions. Endoplasmic reticulum (ER) stress and the unfolded protein response (UPR): Study of the role of ER stress in the expression of genes for ER transferases and lectins that participate in ER folding and quality control using human skin fibroblasts. The UPR response in these cells has been calibrated using various readouts in response to different stresses: 1) 40 nM L-azetidine-2-carboxylate (AZC) 1 hour, 2) 0.2 mg/ml castanospermine, 24 hours, 3) 2 mM Dithiothreitol (DTT), 20 minutes, 4) 100nm Thapsigargin (TG), 30 minutes, 5) 5 ug/ml tunicamycin, 5 hours, 6) untreated control cells
Project description:The unfolded protein response (UPR) is a cellular defense mechanism against glucose deprivation, a cell condition that occurs in solid tumors. A key feature of the UPR is the activation of the transcription program that allows the cell to cope with endoplasmic reticulum (ER) stress. We used micoarrays to show that the UPR transcription program is disrupted by the antitumor macrocyclic compound versipelostatin (VST) and antidiabetic biguanides metformin, buformin and phenformin, depending on cellular glucose availability. Keywords: stress response, drug response
Project description:Accumulated unfolded proteins in the endoplasmic reticulum (ER) will trigger the unfolded protein response (UPR) to increase protein-folding capacity. The ER proteostasis and UPR signaling should be precisely and timely regulated. In the project, by unbiased proteomics analysis, we identify that the serine 357 of protein disulfide isomerase (PDI) is rapidly phosphorylated by the secretory pathway kinase Fam20C under ER stress. Remarkably, phosphorylated Ser357 induces an open conformation of PDI and turns it from a ‘foldase’ to a ‘holdase’, which is critical for preventing protein misfolding in the ER.
Project description:We set out to determine the role of the IRE1/XBP1 pathway, the most ancient and highly conserved endoplasmic reticulum (ER) stress-sensing pathway of the unfolded protein response (UPR), in Schmid metaphyseal chondrodysplasia (MCDS). RNA derived from hypertrophic zones microdissected from growth plates of wildtype mice, mice lacking XBP1 activity in chondrocytes (Xbp1Cart?Ex2), mice carrying a COL10A1 pN617K mutation (ColXN617K), and compound mutants (C/X) was analyzed by whole genome microarray analysis. 1633 probes were differentially expressed between ColXN617K and wildtype, 215 probes were differentially expressed between Xbp1Cart?Ex2 and wildtype, and 1337 probes were differentially expressed between C/X and wildtype. 885 probes were differentially expressed between ColXN617K and wildtype but not Xbp1Cart?Ex2 and wildtype or C/X and wildtype, thus representing the XBP1-dependent response to hypertrophic chondrocyte ER stress. 688 probes were differentially expressed between ColXN617K and wildtype and between C/X and wildtype but not Xbp1Cart?Ex2 and wildtype, thus representing the XBP1-independent response to hypertrophic chondrocyte ER stress. Results were validated by qPCR. Entire growth plate hypertrophic zones were microdissected from one tibia from each of three 2-week old wildtype mice, three 2-week old mice carrying a COL10A1 p.N617K mutation (ColXN617K), three 2-week old mice lacking XBP1 activity in chondrocytes (Xbp1Cart?Ex2), and three 2-week old mice resulting from a cross between ColXN617K and Xbp1Cart?Ex2 (C/X).
Project description:Genome-wide CRISPR-Cas9 knockout screen using TKOv1 sgRNA library was performed in isogenic RBM10-proficient and RBM10-deficient HCC827 cells.
Project description:A human tissue screen identifies a regulator of ER secretion as a brain size determinant. Abstract: Loss-of-function (LOF) screens provide a powerful approach to identify regulators in biological processes. Pioneered in laboratory animals, LOF screens of human genes are currently restricted to two-dimensional (2D) cell culture hindering testing of gene functions requiring tissue context. Here we present CRISPR-LIneage tracing at Cellular resolution in Heterogenous Tissue (CRISPR-LICHT), enabling parallel LOF studies in human cerebral organoid tissue. We used CRISPR-LICHT to test 173 microcephaly candidate genes revealing 25 to be involved in known and uncharacterized microcephaly-associated pathways. We characterized Immediate Early Response 3 Interacting Protein 1 (IER3IP1) regulating the unfolded protein response (UPR) and extracellular matrix (ECM) protein secretion crucial for tissue integrity, with dysregulation resulting in microcephaly. Our human tissue screening technology identifies microcephaly genes and mechanisms involved in brain size control.