title: Lipase-selective functional domains of perilipin A differentially regulate constitutive and protein kinase A-stimulated lipolysis.
abstract: Perilipin (Peri) A is a lipid droplet-associated phosphoprotein that acts dually as a suppressor of basal (constitutive) lipolysis and as an enhancer of cyclic AMP-dependent protein kinase (PKA)-stimulated lipolysis by both hormone-sensitive lipase (HSL) and non-HSL(s). To identify domains of Peri A that mediate these multiple actions, we introduced adenoviruses expressing truncated or mutated Peri A and HSL into NIH 3T3 fibroblasts lacking endogenous perilipins and HSL but overexpressing acyl-CoA synthetase 1 and fatty acid transporter 1. We identified two lipase-selective functional domains: 1) Peri A (amino acids 1-300), which inhibits basal lipolysis and promotes PKA-stimulated lipolysis by HSL, and 2) Peri A (amino acids 301-517), which inhibits basal lipolysis by non-HSL and promotes PKA-stimulated lipolysis by both HSL and non-HSL. PKA site mutagenesis revealed that PKA-stimulated lipolysis by HSL requires phosphorylation of one or more sites within Peri 1-300 (Ser81, Ser222, and Ser276). PKA-stimulated lipolysis by non-HSL additionally requires phosphorylation of one or more PKA sites within Peri 301-517 (Ser433, Ser492, and Ser517). Peri 301-517 promoted PKA-stimulated lipolysis by HSL yet did not block HSL-mediated basal lipolysis, indicating that an additional region(s) within Peri 301-517 promotes hormone-stimulated lipolysis by HSL. These results suggest a model of Peri A function in which 1) lipase-specific "barrier" domains block basal lipolysis by HSL and non-HSL, 2) differential PKA site phosphorylation allows PKA-stimulated lipolysis by HSL and non-HSL, respectively, and 3) additional domains within Peri A further facilitate PKA-stimulated lipolysis, again with lipase selectivity.
authors.affiliation: Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts 02111, USA.
authors.forename: Hui H
authors.initials: HH
authors.lastname: Zhang
authors.forename: Sandra C
authors.initials: SC
authors.lastname: Souza
authors.forename: Kizito V
authors.initials: KV
authors.lastname: Muliro
authors.forename: Fredric B
authors.initials: FB
authors.lastname: Kraemer
authors.forename: Martin S
authors.initials: MS
authors.lastname: Obin
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Greenberg
mesh_terms: D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008049:Lipase / Q000235:genetics / Q000378:metabolism*; D008066:Lipolysis; D051379:Mice; D009154:Mutation; D041681:NIH 3T3 Cells; D000070778:Perilipin-1; D010750:Phosphoproteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D002787:Sterol Esterase / Q000235:genetics / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D000070778:Perilipin-1; D010750:Phosphoproteins; D017868:Cyclic AMP-Dependent Protein Kinases; D002787:Sterol Esterase; D008049:Lipase