Perilipin 5-mediated lipid droplet-mitochondria coupling determines mitochondrial capacity

ABSTRACT: Disturbances in lipid homeostasis can cause mitochondrial dysfunction and lipotoxicity requiring tight regulation of intracellular lipid metabolism and fatty acid (FA) flux. Perilipin 5 (PLIN5) decorates intracellular lipid droplets (LD) in oxidative tissues and controls triacylglycerol (TG) turnover via its interactions with Adipose triglyceride lipase (ATGL) and the ATGL co-activator Comparative gene identification-58 (CGI-58). Furthermore, PLIN5 anchors mitochondria to the LD membrane via its carboxyl-terminal domain. However, the role of this LD-mitochondria coupling (LDMC) in cellular FA flux and energy catabolism is less established. In this study, we investigated the impact of abolished LDMC on cellular FA flux, mitochondrial respiration and protein interaction. To do so, we established novel PLIN5 truncation variants lacking LDMC while maintaining normal interactions with lipolytic key players. Radiotracer studies with transgenic cell lines stably overexpressing either wild type or truncated PLIN5 revealed that LDMC has no significant impact on FA esterification upon lipid loading or TG catabolism during stimulated lipolysis. Moreover, we found that LDMC is not essential for FA shuttling into mitochondria, which was in line with only minor effects of disrupted LDMC on FA oxidation. In contrast, LDMC significantly improved the mitochondrial respiratory capacity and metabolic flexibility of lipid-challenged cardiomyocytes, which was corroborated by LDMC-dependent interactions of PLIN5 with mitochondrial proteins involved in mitochondrial respiration, dynamics and cristae organization. Taken together, this study suggests that PLIN5 preserves mitochondrial function by adjusting FA supply via the regulation of TG hydrolysis and that LDMC is a vital part of mitochondrial integrity.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Heart, Cardiocyte

SUBMITTER: Natalia Kunowska  

LAB HEAD: Urlich Stelzl

PROVIDER: PXD028541 | Pride | 2022-02-11

REPOSITORIES: pride