Control of adipose triglyceride lipase action by serine 517 of perilipin A globally regulates protein kinase A-stimulated lipolysis in adipocytes.
Phosphorylation of the lipid droplet-associated protein perilipin A (Peri A) mediates the actions of cyclic AMP-dependent protein kinase A (PKA) to stimulate triglyceride hydrolysis (lipolysis) in adipocytes. Studies addressing how Peri A PKA sites regulate adipocyte lipolysis have relied on non-adipocyte cell models, which express neither adipose triglyceride lipase (ATGL), the rate-limiting enzyme for triglyceride catabolism in mice, nor the "downstream" lipase, hormone-sensitive lipase (HSL). ATGL and HSL are robustly expressed by adipocytes that we generated from murine embryonic fibroblasts of perilipin knock-out mice. Adenoviral expression of Peri A PKA site mutants in these cells reveals that mutation of serine 517 alone is sufficient to abrogate 95% of PKA (forskolin)-stimulated fatty acid (FA) and glycerol release. Moreover, a "phosphomimetic" (aspartic acid) substitution at serine 517 enhances PKA-stimulated FA release over levels obtained with wild type Peri A. Studies with ATGL-and HSL-directed small hairpin RNAs demonstrate that 1) ATGL activity is required for all PKA-stimulated FA and glycerol release in murine embryonic fibroblast adipocytes and 2) all PKA-stimulated FA release in the absence of HSL activity requires serine 517 phosphorylation. These results provide the first demonstration that Peri A regulates ATGL-dependent lipolysis and identify serine 517 as the Peri A PKA site essential for this regulation. The contributions of other PKA sites to PKA-stimulated lipolysis are manifested only in the presence of phosphorylated or phosphomimetic serine 517. Thus, serine 517 is a novel "master regulator" of PKA-stimulated adipocyte lipolysis.
Miyoshi
Hideaki
H
Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts 02111, USA.
Perfield
James W
JW
Souza
Sandra C
SC
Shen
Wen-Jun
WJ
Zhang
Hui-Hong
HH
Stancheva
Zlatina S
ZS
Kraemer
Fredric B
FB
Obin
Martin S
MS
Greenberg
Andrew S
AS
D000256:Adenoviridae / Q000235:genetics; D017667:Adipocytes / Q000166:cytology / Q000201:enzymology*; D000818:Animals; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D002352:Carrier Proteins; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology; D008049:Lipase; D008066:Lipolysis / Q000502:physiology*; D051379:Mice; D008817:Mice, Mutant Strains; D016297:Mutagenesis, Site-Directed; D000070778:Perilipin-1; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D012694:Serine / Q000378:metabolism; D000217:Acyltransferases
D002265:Carboxylic Ester Hydrolases; D002352:Carrier Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; D008049:Lipase; D000070778:Perilipin-1; D010750:Phosphoproteins; D012694:Serine; C494445:PNPLA2 protein, mouse; D000217:Acyltransferases