Article

Perilipin promotes hormone-sensitive lipase-mediated adipocyte lipolysis via phosphorylation-dependent and -independent mechanisms.

Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts 02111, USA.
Journal of Biological Chemistry (Impact Factor: 4.6). 07/2006; 281(23):15837-44. DOI: 10.1074/jbc.M601097200
Source: PubMed

ABSTRACT Hormone-sensitive lipase (HSL) is the predominant lipase effector of catecholamine-stimulated lipolysis in adipocytes. HSL-dependent lipolysis in response to catecholamines is mediated by protein kinase A (PKA)-dependent phosphorylation of perilipin A (Peri A), an essential lipid droplet (LD)-associated protein. It is believed that perilipin phosphorylation is essential for the translocation of HSL from the cytosol to the LD, a key event in stimulated lipolysis. Using adipocytes retrovirally engineered from murine embryonic fibroblasts of perilipin null mice (Peri-/- MEF), we demonstrate by cell fractionation and confocal microscopy that up to 50% of cellular HSL is LD-associated in the basal state and that PKA-stimulated HSL translocation is fully supported by adenoviral expression of a mutant perilipin lacking all six PKA sites (Peri Adelta1-6). PKA-stimulated HSL translocation was confirmed in differentiated brown adipocytes from perilipin null mice expressing an adipose-specific Peri Adelta1-6 transgene. Thus, PKA-induced HSL translocation was independent of perilipin phosphorylation. However, Peri Adelta1-6 failed to enhance PKA-stimulated lipolysis in either MEF adipocytes or differentiated brown adipocytes. Thus, the lipolytic action(s) of HSL at the LD surface requires PKA-dependent perilipin phosphorylation. In Peri-/- MEF adipocytes, PKA activation significantly enhanced the amount of HSL that could be cross-linked to and co-immunoprecipitated with ectopic Peri A. Notably, this enhanced cross-linking was blunted in Peri-/- MEF adipocytes expressing Peri Adelta1-6. This suggests that PKA-dependent perilipin phosphorylation facilitates (either direct or indirect) perilipin interaction with LD-associated HSL. These results redefine and expand our understanding of how perilipin regulates HSL-mediated lipolysis in adipocytes.

0 Followers
 · 
94 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Energy storage and release at times of food excess or fasting are carefully coordinated processes that depend on the appropriate differentiation of mesenchymal stem cells into mature adipocytes (adipogenesis) forming white adipose tissue (WAT) and on regulatory signals for storage (lipogenesis) or mobilization (lipolysis) of triacylglycerides (TAGs) from lipid droplets. It is widely recognized that cAMP signaling via protein kinase A (PKA) is important both in adipogenesis and for hormonal control and lipolysis in WAT. A kinase anchoring proteins (AKAPs) target PKA to distinct subcellular compartments in close proximity to its specific substrates thereby providing spatial and temporal specificity in the mediation of biological effects controlled by the cAMP-PKA pathway. This review will provide an updated overview of some of the sites of regulation by cAMP in adipogenesis and lipolysis and the involvement of AKAPs and highlighting, as a recent example, the AKAP Optical Atrophy 1 (OPA1) and its role in the phosphorylation of Perilipin to induce lipolysis.
    Hormone and Metabolic Research 09/2014; 46(12). DOI:10.1055/s-0034-1389955 · 2.04 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Anabolic and catabolic signaling oppose one another in adipose tissue to maintain cellular and organismal homeostasis, but these pathways are often dysregulated in metabolic disorders. Although it has long been established that stimulation of the β-adrenergic receptor inhibits insulin-stimulated glucose uptake in adipocytes, the mechanism has remained unclear. Here we report that β-adrenergic-mediated inhibition of glucose uptake requires lipolysis. We also show that lipolysis suppresses glucose uptake by inhibiting the mammalian target of rapamycin (mTOR) complexes 1 and 2 through complex dissociation. In addition, we show that products of lipolysis inhibit mTOR through complex dissociation in vitro. These findings reveal a previously unrecognized intracellular signaling mechanism whereby lipolysis blocks the phosphoinositide 3-kinase-Akt-mTOR pathway, resulting in decreased glucose uptake. This previously unidentified mechanism of mTOR regulation likely contributes to the development of insulin resistance.
    Proceedings of the National Academy of Sciences 11/2014; 111(49). DOI:10.1073/pnas.1410530111 · 9.81 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Perilipins have been reported to limit the interaction of lipases with neutral lipids within the droplets, thereby regulating neutral lipid accumulation and utilization. This study aimed to identify the location and expression of PLIN1 and PLIN2 in porcine oocytes during maturation. Quantitative real-time polymerase chain reaction (qRT-PCR), immunostaining and Western blot methods were used to characterize the expression and distribution patterns of PLIN1 and PLIN2 in porcine oocytes. The results showed that PLIN1 was not detectable in porcine oocytes. PLIN2 and BODIPY 493/503-detected neutral lipid droplets appeared identical distribution patterns and extensive colocalization in both GV and MII porcine oocytes. PLIN2 protein expression was higher in GV oocytes than that in MII oocytes (p < 0.05), although PLIN2 mRNA expression was similar in both groups. These findings suggested that PLIN2 was a major lipid droplet-associated protein in porcine oocytes.
    Reproduction in Domestic Animals 08/2014; 49(5). DOI:10.1111/rda.12386 · 1.18 Impact Factor

Full-text (2 Sources)

Download
26 Downloads
Available from
May 16, 2014