Homo sapiens
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA762582 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR15879409.fastq.gz | Fastqsanger.gz | |||
| SRR15879409_1.fastq.gz | Fastqsanger.gz | |||
| SRR15879409_2.fastq.gz | Fastqsanger.gz |
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Project description:Lipid droplets protect human β-cells from lipotoxic-induced stress and cell identity changes
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Project description:Palm and coconut oils are linked to cardiovascular disease and diabetes because of their high saturated fatty acid (SFA) content but exactly how exogenous SFAs, but not unsaturated fatty acids (UFA), are toxic to cells remains unknown. In insulin-producing, β-cells of the Islets of Langerhans, loss of which exacerbates diabetes, we found that SFAs but not UFAs were toxic because they disable a highly conserved lipid droplet biogenesis machinery. We show that palmitate (a major SFA of these oils), but not palmitoleic or oleic, S-acylates the highly conserved ER-resident FITM2 protein, required for lipid coalescence and droplet budding from the ER. The S-acylation marks FITM2 for ubiquitination and proteosomal degradation, leaving SFAs within the ER instead safe sequestration within lipid droplets. ER-stress ensues with rapid induction of ER stress leading to β-cell apoptosis. Specific deletion of FITM2 in β-cells disrupts calcium signaling and key β-cell TFs and exacerbates high fat diet-induced ER stress and diabetes. Rescue by overexpression ameliorates ER-stress and β-cell apoptosis thus demonstrating an important link between lipid species and cell ability to sequester them away from the ER in the form of lipid droplets.
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Project description:The number, size, and composition of lipid droplets can be influenced by dietary changes that shift energy substrate availability. This diversification of lipid droplets can promote metabolic flexibility and shape cellular stress responses in unique tissues with distinctive metabolic roles. Using Drosophila, we uncovered a role for myocyte enhancer-factor 2 (MEF2) in modulating diet-dependent lipid droplet diversification within adult striated muscle, impacting mortality rates. Muscle-specific attenuation of MEF2, whose chronic activation maintains glucose and mitochondrial homeostasis, leads to the accumulation of large, cholesterol ester-enriched intramuscular lipid droplets in response to high calorie, carbohydrate sufficient diets. The diet-dependent accumulation of these lipid droplets also correlates with both enhanced stress protection in muscle and increases in organismal lifespan. Furthermore, MEF2 attenuation releases an antagonistic regulation of cell cycle gene expression programs, and up-regulation of Cyclin E is required for diet-and-MEF2 dependent diversification of intramuscular lipid droplets. The integration of MEF2-regulated gene expression networks with dietary responses thus plays a critical role in shaping muscle metabolism and function, further influencing organismal lifespan. Together, these results highlight a potential protective role for intramuscular lipid droplets during dietary adaptation.
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Project description:Metabolic disorders such as obesity and nonalcoholic fatty liver disease (NAFLD) are emerging disorders that affect the global population. One facet of the disorders is attributed to the disturbance of membrane lipid homeostasis. Perturbation of endoplasmic reticulum (ER) homeostasis through changes in membrane phospholipid composition results in activation of the unfolded protein response (UPR) and causes dramatic translational and transcriptional changes in cell. To restore cellular homeostasis, the three highly conserved UPR transducers ATF6, IRE1, and PERK mediate cellular processes upon ER stress. The roles of the UPR in proteostatic stress caused by the accumulation of misfolded protein is well understood but lipid perturbation-induced UPR remains elusive. We found that genetically attenuated PC synthesis in C. elegans causes lipid droplets accumulation if not for the intervention of the UPR program. Transcriptional profiling of lipid perturbation-induced ER stress animals shows a unique subset of genes modulated in an UPR-dependent manner that are unaffected by proteostatic stress. Among these, we identified IRE1-modulated autophagy genes that trigger liberation of free fatty acids from excess lipid droplets suggesting a stress release mechanism by which free fatty acids are rechannelling to restore lipid homeostasis. Considering the important role of lipid homeostasis and how its impairment contributes to the pathologies in metabolic diseases, our data uncovers the indispensable role of a fully functional UPR program in regulating lipid homeostais in the face of chronic ER stress.
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Project description:Proinflammatory cytokines are important mediators of pancreatic beta cell dysfunction and demise in type 1 diabetes (T1D). We presently characterized human beta cell responses to IFNa by combining ATAC-seq, RNA-seq and proteomics assays. The initial beta cell response to IFNa was characterized by major chromatin remodeling, followed by marked changes in transcriptional and translational regulation. IFNa-induced changes in alternative splicing (AS) and first exon usage increased the diversity of transcripts expressed by beta cells. This, combined with changes observed on protein modification/degradation, ER stress and MHC class I, may significantly expand the peptide repertoire presented by beta cells to the immune system. On the other hand, beta cells up-regulated checkpoint proteins, such as PDL1 and HLA-E, that may protect them against the autoimmune assault. Data mining of the present multi-omics analysis led to the identification of two compound classes that revert IFNa effects on human beta cells and may be translated to clinical trials.
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