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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #211433
Title: Control of Adipose Triglyceride Lipase Action by Serine 517 of Perilipin A Globally Regulates Protein Kinase A-stimulated Lipolysis in Adipocytes

Author
item MIYOSHI, HIDEAKI - TUFTS/HNRCA
item PERFIELD, JAMES - TUFTS/HNRCA
item SOUZA, SANDRA - TUFTS/HNRCA
item SHEN, WEN-JUN - VA PALO ALTO HEALTH CARE
item ZHANG, HUI-HONG - TUFTS/HNRCA
item STANCHEVA, ZLATINA - TUFTS/HNRCA
item KRAEMER, FREDRIC - VA PALO ALTO HEALTH CARE
item OBIN, MARTIN - TUFTS/HNRCA
item Greenberg, Andrew

Submitted to: Journal of Biological Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2006
Publication Date: 1/12/2007
Citation: Miyoshi, H., Perfield, J.W., Souza, S.C., Shen, W., Zhang, H., Stancheva, Z., Kraemer, F.B., Obin, M.S., Greenberg, A.S. 2007. Control of Adipose Triglyceride Lipase Action by Serine 517 of Perilipin A Globally Regulates Protein Kinase A-stimulated Lipolysis in Adipocytes. Journal of Biological Chemistry. 282(2): 996-1002.

Interpretive Summary: Phosphorylation is the addition of a phosphate group to a protein molecule and is often an important regulatory event. When the protein perilipin A is phosphorylated, it mediates the actions of protein kinase A, which is a cyclic AMP-dependent protein, to stimulate fat breakdown in fat cells. Past studies addressing how perilipin and protein kinase A sites regulate fat cell breakdown have relied on non-fat cell models, which express neither the rate-limiting enzyme for triglyceride breakdown in mice called adipose triglyceride lipase, nor the "downstream" enzyme called hormone-sensitive lipase. Both adipose triglyceride lipase and hormone-sensitive lipase are strongly expressed by fat cells that we generated from mice that lack the perilipin gene. Studies with silenced gene expression of both adipose triglyceride lipase and hormone sensitive lipase demonstrate that 1) fat tissue triglyceride lipase activity is required for all protein kinase A-stimulated fatty acid release in embryonic mouse fat cells and 2) all protein kinase A-stimulated fatty acid release in the absence of hormone sensitive lipase activity requires the amino acid serine 517 to be phosphorylated. These results provide the first demonstration that perilipin A regulates adipose triglyceride lipase fat breakdown and identify serine 517 as the essential regulation site for perilipin A and protein kinase A. The contributions of other protein kinase A sites to fat breakdown are manifested only in the presence of serine 517. Thus, serine 517 is a novel "master regulator" of protein kinase A-stimulated fat cell breakdown.

Technical Abstract: 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 sties 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.