title: Cellular localization and associations of the major lipolytic proteins in human skeletal muscle at rest and during exercise.
abstract: Lipolysis involves the sequential breakdown of fatty acids from triacylglycerol and is increased during energy stress such as exercise. Adipose triglyceride lipase (ATGL) is a key regulator of skeletal muscle lipolysis and perilipin (PLIN) 5 is postulated to be an important regulator of ATGL action of muscle lipolysis. Hence, we hypothesized that non-genomic regulation such as cellular localization and the interaction of these key proteins modulate muscle lipolysis during exercise. PLIN5, ATGL and CGI-58 were highly (>60%) colocated with Oil Red O (ORO) stained lipid droplets. PLIN5 was significantly colocated with ATGL, mitochondria and CGI-58, indicating a close association between the key lipolytic effectors in resting skeletal muscle. The colocation of the lipolytic proteins, their independent association with ORO and the PLIN5/ORO colocation were not altered after 60 min of moderate intensity exercise. Further experiments in cultured human myocytes showed that PLIN5 colocation with ORO or mitochondria is unaffected by pharmacological activation of lipolytic pathways. Together, these data suggest that the major lipolytic proteins are highly expressed at the lipid droplet and colocate in resting skeletal muscle, that their localization and interactions appear to remain unchanged during prolonged exercise, and, accordingly, that other post-translational mechanisms are likely regulators of skeletal muscle lipolysis.
authors: Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia.
authors: Rachael R
authors: RR
authors: Mason
authors: Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia.
authors: Ruth C R
authors: RC
authors: Meex
authors: Centre of Physical Activity and Nutrition (C-PAN) Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, Australia.
authors: Aaron P
authors: AP
authors: Russell
authors: Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia.
authors: Benedict J
authors: BJ
authors: Canny
authors: Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia.
authors: Matthew J
authors: MJ
authors: Watt
mesh_terms: D051103:1-Acylglycerol-3-Phosphate O-Acyltransferase / Q000032:analysis* / Q000378:metabolism; D000328:Adult; D002478:Cells, Cultured; D015444:Exercise / Q000502:physiology*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000032:analysis* / Q000378:metabolism; D008049:Lipase / Q000032:analysis* / Q000378:metabolism; D008066:Lipolysis; D018485:Muscle Fibers, Skeletal / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D009124:Muscle Proteins / Q000032:analysis* / Q000378:metabolism; D018482:Muscle, Skeletal / Q000502:physiology* / Q000648:ultrastructure; D000070797:Perilipin-5; D012146:Rest / Q000502:physiology*; D055815:Young Adult; D000217:Acyltransferases
chemical_list: D051103:1-Acylglycerol-3-Phosphate O-Acyltransferase; D047908:Intracellular Signaling Peptides and Proteins; D008049:Lipase; D009124:Muscle Proteins; D000070797:Perilipin-5; C544352:PLIN5 protein, human; C439972:ABHD5 protein, human; C494794:PNPLA2 protein, human; D000217:Acyltransferases