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Project description:The proteasome is the main proteolytic system for targeted protein degradation in the cell. Its function is fine-tuned according to cellular needs. Inhibition of the respiratory chain impairs proteasome activity, regulation of proteasome function by mitochondrial metabolism, however, is unknown. Here, we demonstrate that mitochondrial dysfunction reduces the assembly and activity of the 26S proteasome. Defects in respiratory chain caused metabolic reprogramming of the Krebs cycle and deficiency in the amino acid aspartate resulting in reduced 26S proteasome function. Aspartate supplementation fully restored assembly and activity of 26S proteasome complexes. This metabolic reprogramming involved sensing of aspartate via the mTORC1 pathway and the mTORC1-dependent transcriptional activation of defined proteasome assembly factors. Metabolic regulation of 26S function was confirmed in patient-derived skin fibroblasts with respiratory dysfunction containing a single mitochondrial mutation. Importantly, treatment of primary human lung fibroblasts with the respiratory chain inhibitor and anti-diabetic drug metformin similarly reduced assembly and activity of 26S proteasome complexes, which was fully reversible and rescued by supplementation of aspartate or pyruvate. Of note, reduced 26S activity conferred increased resistance towards the proteasome inhibitor Bortezomib, which was reversible upon pyruvate supplementation. Our study uncovers a fundamental novel mechanism of how mitochondrial metabolism adaptively adjusts protein degradation by the proteasome. It thus unravels unexpected consequences of defective mitochondrial metabolism in disease or drug-targeted mitochondrial reprogramming for proteasomal protein degradation in the cell. As metabolic inhibition of proteasome function can be alleviated by treatment with aspartate or pyruvate, our results also have therapeutic implications.
2020-07-26 | GSE153983 | GEO
Project description:Many neurodegenerative disorders are characterized by two pathological hallmarks: progressive loss of neurons and occurrence of inclusion bodies containing ubiquitinated proteins. The mechanisms responsible for these pathological features remain elusive. Inflammation may be critical to neurodegeneration associated with ubiquitin-protein aggregates. We previously showed that prostaglandin J2 (PGJ2), one of the endogenous products of inflammation, induces neuronal death and accumulation of ubiquitinated proteins into distinct aggregates. We now report that temporal microarray analysis of human neuroblastoma SK-N-SH cells treated with PGJ2 revealed changes relevant to neurodegeneration. PGJ2 triggered a “repair” response including increased expression of heat shock, protein folding, stress and cellular defense genes. PGJ2 also decreased expression of DNA repair genes and increased expression of apoptotic genes. Overtime pro-death responses prevailed over pro-survival responses, leading to cellular demise. Furthermore, PGJ2 increased the expression of proteasome and other ubiquitin-proteasome pathway genes. This increase failed to overcome PGJ2-inhibition of 26S proteasome activity. Ubiquitinated proteins are degraded by the 26S proteasome, shown here to be the most active proteasomal form in SK-N-SH cells. We demonstrate that PGJ2 impairs 26S proteasome assembly, which is an ATP-dependent process. Interestingly, PGJ2 is known to perturb mitochondrial function, which could be critical to the observed 26S proteasome disassembly and suggest a crosstalk between mitochondrial and proteasomal impairment. In conclusion neurotoxic products of inflammation, such as PGJ2, may play a role in neurodegenerative disorders associated with the aggregation of ubiquitinated proteins by impairing 26S proteasome activity and inducing a chain of events that culminates in neuronal cell death. Keywords: Drug response time course
2006-06-01 | GSE4329 | GEO
Project description:Proteasomes are a critical component of quality control that regulates turnover of short-lived, unfolded, and misfolded proteins. Proteasome activity has been therapeutically targeted and considered as a treatment option for several chronic lung disorders including pulmonary fibrosis. Though pharmacologic inhibition of proteasome activity effectively prevents the transformation of fibroblasts to myofibroblasts, the effect on alveolar type 2 (AT2) epithelial cells is not clear. To address this knowledge gap, we generated a genetic model in which a proteasome subunit, RPT3, which promotes assembly of active 26S proteasome, was conditionally deleted in AT2 cells of mice. Targeted deletion of RPT3 in AT2 cells resulted in 26S proteasome dysfunction, leading to augmented cell stress and death. Acute loss of AT2 cells resulted in depletion of alveolar surfactant, disruption of the alveolar epithelial barrier and, ultimately, lethal acute respiratory distress syndrome. This study underscores the need for further investigation into the differential effect of proteasome inhibition in lung cell types.
2019-08-29 | GSE123873 | GEO
Project description:Sarcolipin (SLN) is a key regulator of SERCA pump in atria. To determine the role of SLN in atrial Ca2+ homeostasis, we have generated a SLN null (sln-/-) mouse model. Ablation of SLN results in increased SR Ca2+ load and Ca2+ transients in atria. Further, loss of SLN results in electrophysiological and strcutural remodeling of atria. The SLN knockout and C57/BL6 wildtype mice (each n=3) were selected for RNA extraction. The cRNA probes were hybridized to Affymetrix gene array.
2010-11-01 | E-GEOD-23403 | biostudies-arrayexpress
Project description:RNA quality control (RQC) and post-transcriptional gene silencing (PTGS) target and degrade aberrant endogenous RNAs and foreign RNAs, contributing to homeostasis of cellular RNAs. In plants, RQC and PTGS compete for foreign and selected endogenous RNAs; however, little is known about the mechanism interconnecting the two pathways. Using a reporter system designed for monitoring PTGS, we revealed that the 26S proteasome subunit RPT2a enhances transgene PTGS by promoting the accumulation of transgene-derived short interfering RNAs without affecting their biogenesis. RPT2a physically associated with a subset of RQC components and downregulated the protein level. Overexpression of the RQC components interfered with transgene silencing, and impairment of the RQC machinery reinforced transgene PTGS attenuated by rpt2a. Overall, we demonstrate that the 26S proteasome subunit RPT2a promotes PTGS by repressing the RQC machinery to control foreign RNAs.
2019-08-29 | GSE131009 | GEO
Project description:Bruton’s tyrosine kinase (BTK) inhibitor Ibrutinib has been shown to synergize in vitro with proteasome inhibitors (PIs) in reducing the viability of cells derived from B-cell malignancies, but the mechanism is not known. We report here that an off-target effect of Ibrutinib causes synergy because not all BTK inhibitors exhibited the synergistic effect, and those that synergized did so even in cells that do not express BTK. The allosteric BTK inhibitor CGI-1746 showed the strongest synergy. Co-treatment of cells with CGI-1746 increased PI-induced expression of heat shock proteins and accumulation of ubiquitin conjugates. The CGI-1746 inhibited the degradation of a model substrate by a purified 26S proteasome. CGI-1746, but not other BTK inhibitors, allosterically inhibited ATPase activity and 2 and 1 peptidase activities of the 26S proteasomes. Although the effect is unlikely to contribute to the anti-neoplastic activity of BTK inhibitors in multiple myeloma and mantle cell lymphoma, it demonstrates a conceptually novel mode of inhibition that may aid the development of more potent proteasome inhibitors and improve response in solid tumors clinically.
2023-08-01 | GSE239482 | GEO
Project description:Coordinated regulation of the ubiquitin-proteasome system is crucial for the cell to adjust its protein degradation capacity to changing proteolytic requirements. The transcription factor TCF11 has been identified as a regulator for 26S-proteasome formation in human cells to compensate for reduced proteolytic activity. To expand the current knowledge of other UPS-related TCF11 target genes in response to epoxomicin, we performed microarray analyses of cells exposed to epoxomicin and with or without depletion of TCF11. Keywords: siRNA depletion Human Ea.hy926 cells were harvested 24 hours following treatment with 10nM epoxomicin or DMSO as a solvent control and with transfection of control siRNA or TCF11-specific siRNA for RNA extraction and hybridization on Affymetrix microarrays.
2010-10-08 | E-GEOD-22853 | biostudies-arrayexpress
Project description:Sarcolipin (SLN) is a key regulator of SERCA pump in atria. To determine the role of SLN in atrial Ca2+ homeostasis, we have generated a SLN null (sln-/-) mouse model. Ablation of SLN results in increased SR Ca2+ load and Ca2+ transients in atria. Further, loss of SLN results in electrophysiological and strcutural remodeling of atria.
2010-11-01 | GSE23403 | GEO
Project description:This project carries out the pilot CRISPR/Cas9 screens in the K562 background. Its goals are to confirm that positive controls work, and to assess the effects of experimental parameters (listed below) on the sequencing-based fitness readout. We test 1) length of selection 2) biological replicates 3) sampling variation during bottlenecks 4) sampling variation during DNA preparation 5) sequencing depth to inform the setup for the next round of experiments. To do so, we propose to sequence 13 samples (6 timepoints, 2 biological replicates, 2 severe bottlenecks during growth, 2 bottlenecks during DNA preparation, and the screening library itself) on two lanes of HiSeq, using 19bp reads. The sequencing libraries are prepared in our lab.This data is part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/
2016-05-03 | E-ERAD-459 | biostudies-arrayexpress
Project description:Coordinated regulation of the ubiquitin-proteasome system is crucial for the cell to adjust its protein degradation capacity to changing proteolytic requirements. The transcription factor TCF11 has been identified as a regulator for 26S-proteasome formation in human cells to compensate for reduced proteolytic activity. To expand the current knowledge of other UPS-related TCF11 target genes in response to epoxomicin, we performed microarray analyses of cells exposed to epoxomicin and with or without depletion of TCF11. Keywords: siRNA depletion
2010-10-08 | GSE22853 | GEO