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Skeletal muscle lipid droplets are resynthesized before being coated with perilipin proteins following prolonged exercise in elite male triathletes.

07:00 EST 14th January 2020 | BioPortfolio

Summary of "Skeletal muscle lipid droplets are resynthesized before being coated with perilipin proteins following prolonged exercise in elite male triathletes."

Intramuscular triglycerides (IMTG) are a key substrate during prolonged exercise, but little is known about the rate of IMTG resynthesis in the post-exercise period. We investigated the hypothesis that the distribution of the lipid droplet (LD)-associated perilipin (PLIN) proteins is linked to IMTG storage following exercise. 14 elite male triathletes (27±1 y, 66.5±1.3 mL.kg.min) completed 4 h of moderate-intensity cycling. During the first 4 h of recovery, subjects received either carbohydrate or HO, after which both groups received carbohydrate. Muscle biopsies collected pre and post-exercise, and 4 h and 24 h post-exercise were analysed using confocal immunofluorescence microscopy for fibre type-specific IMTG content and PLIN distribution with LDs. Exercise reduced IMTG content in type I fibres (-53%, =0.002), with no change in type IIa fibres. During the first 4 h of recovery, IMTG content increased in type I fibres (=0.014), but was not increased further after 24 h where it was similar to baseline levels in both conditions. During recovery the number of LDs labelled with PLIN2 (70%), PLIN3 (63%) and PLIN5 (62%; all <0.05) all increased in type I fibres. Importantly, the increase in LDs labelled with PLIN proteins only occurred at 24 h post-exercise. In conclusion, IMTG resynthesis occurs rapidly in type I fibres following prolonged exercise in highly-trained individuals. Further, increases in IMTG content following exercise preceded an increase in the number of LDs labelled with PLIN proteins. These data, therefore, suggest that the PLIN proteins do not play a key role in post-exercise IMTG resynthesis.

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Name: American journal of physiology. Endocrinology and metabolism
ISSN: 1522-1555
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Medical and Biotech [MESH] Definitions

A perilipin protein characterized by an extensive 11-mer repeat region, which forms five adjacent alpha-helices. It is expressed primarily in WHITE ADIPOSE TISSUE and differentiating ADIPOCYTES, as well as skeletal muscle and heart. It is soluble in the cytoplasm but re-localizes to the surface of LIPID DROPLETS under high lipid conditions.

A perilipin that localizes to LIPID DROPLETS; CYTOPLASM; ENDOSOMES; and PLASMA MEMBRANE, especially in MACROPHAGES. It functions as a transporter of free fatty acids to lipid droplets to promote their biogenesis and growth. It is also required for the transport of the MANNOSE-6-PHOSPHATE RECEPTOR from endosomes to the TRANS-GOLGI NETWORK. Its structure consists of four helix bundles that interact with the hydrophobic lipid droplet surface.

A perilipin that functions in LIPOGENESIS; LIPOLYSIS; and fatty acid oxidation in BROWN ADIPOSE TISSUE; heart, liver, and skeletal muscle. It recruits MITOCHONDRIA to the surface of LIPID DROPLETS where it functions in both the storage of fatty acids as TRIGLYCERIDES, and their release for mitochondrial fatty acid oxidation in response to metabolic needs.

A perilipin that is expressed by many different cell types. It binds FATTY ACIDS and CHOLESTEROL, stabilizes TRIGLYCERIDES, and localizes to both the surface and hydrophobic core of LIPID DROPLETS, as well as the ENDOPLASMIC RECTICULUM and PLASMA MEMBRANE in MACROPHAGES. It also plays a central role in the biogenesis of lipid droplets and FOAM CELLS and is highly expressed by macrophages at atherosclerotic lesions in human arteries along with the INFLAMMATION markers TNF-ALPHA; MCP-1 RECEPTOR; and IL-6.

Large, multinucleate single cells, either cylindrical or prismatic in shape, that form the basic unit of SKELETAL MUSCLE. They consist of MYOFIBRILS enclosed within and attached to the SARCOLEMMA. They are derived from the fusion of skeletal myoblasts (MYOBLASTS, SKELETAL) into a syncytium, followed by differentiation.

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