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High muscle triglyceride content in obesity is not due to elevated lipogenic enzyme activity or to the suppression of lipolytic proteins
Author(s) -
Li Minghua,
Paran Christopher,
Wolins Nathan E,
Horowitz Jeffrey F
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.1045.8
Subject(s) - adipose triglyceride lipase , medicine , endocrinology , hormone sensitive lipase , perilipin , triglyceride , lipolysis , skeletal muscle , diacylglycerol kinase , acyltransferase , monoacylglycerol lipase , chemistry , biology , adipose tissue , enzyme , biochemistry , cholesterol , protein kinase c , receptor , endocannabinoid system
We compared key factors that regulate intramyocellular triglyceride (IMTG) metabolism and IMTG trafficking between obese (OB) and lean (LN) women. Skeletal muscle biopsy samples from 8 OB and 9 LN women (BMI: 38±1 and 23±1kg/m 2 ) were obtained after an overnight fast. Despite a nearly 2‐fold greater IMTG concentration in OB vs LN (75±15 vs 40±8 umol/g dw; p<0.05), we found protein abundance of the IMTG synthetic enzyme diacylglycerol acyltransferase 1 (DGAT1) to be lower in OB (p<0.01), with a similar trend for a lower DGAT activity in OB (370±47 vs 441±57 pmol/min/mg; p=0.18). Neither the protein level nor activity of the glycerol‐3‐phosphate acyltransferase (GPAT) was different between groups. We found no differences between groups in muscle adipose triglyceride lipase (ATGL) and hormone sensitive lipase (HSL) protein abundance, and no differences in phosphorylation of specific sites known to affect HSL activity. Protein abundances of the IMTG trafficking proteins perilipin 2 and 3 were lower (p<0.05) in muscle from OB vs LN when expressed relative to IMTG content. Our findings indicate that the elevated IMTG content found in obese women was not due to an up‐regulation of key lipogenic proteins, or to the suppression of lipolytic proteins. The impact of lower levels of IMTG trafficking perilipins remains to be clarified. Supported by NIH Grant #R01 DK071955