In diabetic patients, dyslipidemia frequently contributes to organ damage such as diabetic kidney disease (DKD). Dyslipidemia is associated with both excessive deposition of triacylglycerol (TAG) in lipid droplets (LD) and lipotoxicity. Yet, it is unclear how these two effects correlate with each other in the kidney and how they are influenced by dietary patterns. By using a diabetes mouse model, we find here that high fat diet enriched in the monounsaturated oleic acid (OA) caused more lipid storage in LDs in renal proximal tubular cells (PTC) but less tubular damage than a corresponding butter diet with the saturated palmitic acid (PA). This effect was particularly evident S2/S3 but not S1 segments of the proximal tubule. Combining transcriptomics, lipidomics and functional studies, we identify endoplasmic reticulum (ER) stress as the main cause of PA-induced PTC injury. Mechanistically, ER stress is caused by elevated levels of saturated TAG precursors, reduced LD formation and, consequently, higher membrane order in the ER. Simultaneous addition of OA rescues the cytotoxic effects by normalizing membrane order and by increasing both TAG and LD formation. Our study thus emphasizes the importance of monounsaturated fatty acids for the dietary management of DKD by preventing lipid bilayer stress in the ER and promoting TAG and LD formation in PTCs.
- iRECs lipidomic data have been deposited in Dryadhttps://doi.org/10.5061/dryad.x95x69pm1.- Kidney cortex of diabetic mice lipidomic data have been deposited in Dryadhttps://doi.org/10.5061/dryad.qv9s4mwgx.- iRECs Transcriptome raw data (bam files) can be found at https://www.ncbi.nlm.nih.gov/sra/PRJNA809508- iRECs Transcriptome processed data (FPKM and DEG) have been deposited in DryadDOI https://doi.org/10.5061/dryad.gqnk98sq7-The full code for the TF activity-lipid correlation analysis can be found in: https://github.com/saezlab/Albert_perez_RNA_lipid/tree/main/scripts
Data from: Reducing lipid bilayer stress by monounsaturated fatty acids protects renal proximal tubules in diabetesryad Digital Repository, doi:10.5061/dryad.x95x69pm1.
Data from: Reducing lipid bilayer stress by monounsaturated fatty acids protects renal proximal tubules in diabetesDryad Digital Repository, doi:10.5061/dryad.qv9s4mwgx.
Lipotoxicity in renal tubular epithelial cellsNCBI BioProject, PRJNA809508.
Data from: Reducing lipid bilayer stress by monounsaturated fatty acids protects renal proximal tubules in diabetesDryad Digital Repository, doi:10.5061/dryad.
- Jiayi Li
- Suresh Ramakrishnan
- Matias Simons
- Kelli Grand
- Soeren S Lienkamp
- Albert Pérez-Martí
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: All of the experimental protocols in this study were performed with the approval of the animal experimentation ethics committee of the University Paris Descartes (CEEA 34), projects registered as 17-058 and 20-022
- Raymond Harris
- Received: October 1, 2021
- Accepted: May 11, 2022
- Accepted Manuscript published: May 12, 2022 (version 1)
© 2022, Pérez-Martí et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Proliferating cells undergo metabolic changes in synchrony with cell cycle progression and cell division. Mitochondria provide fuel, metabolites, and ATP during different phases of the cell cycle, however it is not completely understood how mitochondrial function and the cell cycle are coordinated. CLUH is a post-transcriptional regulator of mRNAs encoding mitochondrial proteins involved in oxidative phosphorylation and several metabolic pathways. Here, we show a role of CLUH in regulating the expression of astrin, which is involved in metaphase to anaphase progression, centrosome integrity, and mTORC1 inhibition. We find that CLUH binds both the SPAG5 mRNA and its product astrin, and controls the synthesis and the stability of the full-length astrin-1 isoform. We show that CLUH interacts with astrin-1 specifically during interphase. Astrin-depleted cells show mTORC1 hyperactivation and enhanced anabolism. On the other hand, cells lacking CLUH show decreased astrin levels and increased mTORC1 signaling, but cannot sustain anaplerotic and anabolic pathways. In absence of CLUH, cells fail to grow during G1, and progress faster through the cell cycle, indicating dysregulated matching of growth, metabolism and cell cycling. Our data reveal a role of CLUH in coupling growth signaling pathways and mitochondrial metabolism with cell cycle progression.
A developing understanding suggests that spatial compartmentalisation in pancreatic β cells is critical in controlling insulin secretion. To investigate the mechanisms, we have developed live-cell sub-cellular imaging methods using the mouse organotypic pancreatic slice. We demonstrate that the organotypic pancreatic slice, when compared with isolated islets, preserves intact β cell structure, and enhances glucose dependent Ca2+ responses and insulin secretion. Using the slice technique, we have discovered the essential role of local activation of integrins and the downstream component, focal adhesion kinase, in regulating β cells. Integrins and focal adhesion kinase are exclusively activated at the β cell capillary interface and using in situ and in vitro models we show their activation both positions presynaptic scaffold proteins, like ELKS and liprin, and regulates glucose dependent Ca2+ responses and insulin secretion. We conclude that focal adhesion kinase orchestrates the final steps of glucose dependent insulin secretion within the restricted domain where β cells contact the islet capillaries.