Biology subjects

Kakimoto, P.

Publications and source records attributed to Kakimoto, P..

2 recordsLinked to original sources

bioRxiv2023

A Spatiotemporal Proteomic Map of Human Adipogenesis

White adipocytes function as the major energy reservoir in humans by storing substantial amounts of triglycerides and their dysfunction is associated with metabolic disorders. However, the mechanisms underlying cellular specialization during adipogenesis remain unknown. Here, using a high-sensitivity-high throughput workflow, we generated a spatiotemporal proteomic atlas of human adipogenesis encompassing information for ~8.000 proteins. Our systematic approach gives insights into cellular remodeling and the spatial reorganization of metabolic pathways to optimize cells for lipid accumulation and highlights the coordinated regulation of protein localization and abundance during adipogenesis. More specifically, we identified a compartment-specific regulation of protein levels and localization changes of metabolic enzymes to reprogram branched chain amino acid and one-carbon metabolism to provide building blocks and reduction equivalents for lipid synthesis. Additionally, we identified C19orf12 as a differentiation induced and adipocyte-specific lipid droplet (LD) protein, which interacts with the translocase of the outer membrane (TOM) complex of LD associated mitochondria and regulates adipocyte lipid storage. Overall, our study provides a comprehensive resource for understanding human adipogenesis and for future discoveries in the field. KEY POINTSO_LIHuman adipogenesis induces distinct temporal changes in protein abundance C_LIO_LI20% of all detected proteins change organellar localization during adipogenesis C_LIO_LIBCAA and one-carbon metabolism enzyme levels and localizations are coordinately regulated to promote adipogenesis C_LIO_LIC19orf12 is an adipocyte specific LD protein and regulator of lipid storage C_LI

molecular biology↗

bioRxiv2020

Increased glycolysis is an early outcome of palmitate-mediated lipotoxicity

Palmitic acid is the most abundant saturated fatty acid in human serum. In cell culture systems, palmitate overload is considered a toxic stimulus, and promotes lipid accumulation, insulin resistance, endoplasmic reticulum stress, oxidative stress, as well as cell death. An increased supply of fatty acids has also been shown to change the predominant form of the mitochondrial network, although the metabolic effects of this change are still unclear. Here, we aimed to uncover the early bioenergetic outcomes of lipotoxicity. We incubated hepatic PLC/PRF/5 cells with palmitate conjugated to BSA and followed real-time oxygen consumption and extracellular acidification for 6 hours. Palmitate increased glycolysis as soon as 1 hour after the stimulus, while oxygen consumption was not disturbed, despite overt mitochondrial fragmentation and cellular reductive imbalance. Palmitate only induced mitochondrial fragmentation if glucose and glutamine were available, while glycolytic enhancement did not require glutamine, showing it is not dependent on morphological changes. NAD(P)H levels were significantly abrogated in palmitate-treated cells. Knockdown of the mitochondrial NAD(P) transhydrogenase or addition of the mitochondrial oxidant-generator menadione in control cells modulated ATP production from glycolysis. Indeed, using selective inhibitors, we found that the production of superoxide/hydrogen peroxide at the IQ site of electron transport chain complex I is associated with the metabolic rewiring promoted by palmitate, while not changing mitochondrial oxygen consumption. In conclusion, we demonstrate that increased glycolytic flux linked to mitochondrially-generated redox imbalance is an early bioenergetic result of palmitate overload and lipotoxicity.

biochemistry↗