Identification of a novel phosphorylation site in adipose triglyceride lipase as a regulator of lipid droplet localization

Xitao Xie, Paul Langlais, Xiaodong Zhang, Bradlee L. Heckmann, Alicia M. Saarinen, Lawrence J. Mandarino, Jun Liu

    Research output: Contribution to journalArticle

    14 Scopus citations

    Abstract

    Adipose triglyceride lipase (ATGL), the rate-limiting enzyme for triacylglycerol (TG) hydrolysis, has long been known to be a phosphoprotein. However, the potential phosphorylation events that are involved in the regulation of ATGL function remain incompletely defined. Here, using a combinatorial proteomics approach, we obtained evidence that at least eight different sites of ATGL can be phosphorylated in adipocytes. Among them, Thr372 resides within the hydrophobic region known to mediate lipid droplet (LD) targeting. Although it had no impact on the TG hydrolase activity, substitution of phosphorylation-mimic Asp for Thr372 eliminated LD localization and LD-degrading capacity of ATGL expressed in HeLa cells. In contrast, mutation of Thr372 to Ala gave a protein that bound LDs and functioned the same as the wild-type protein. In nonstimulated adipocytes, the Asp mutation led to decreased LD association and basal lipolytic activity of ATGL, whereas the Ala mutation produced opposite effects. Moreover, the LD translocation of ATGL upon β-adrenergic stimulation was also compromised by the Asp mutation. In accord with these findings, the Ala mutation promoted and the Asp mutation attenuated the capacity of ATGL to mediate lipolysis in adipocytes under both basal and stimulated conditions. Collectively, these studies identified Thr372 as a novel phosphorylation site that may play a critical role in determining subcellular distribution as well as lipolytic action of ATGL.

    Original languageEnglish (US)
    Pages (from-to)E1449-E1459
    JournalAmerican Journal of Physiology - Endocrinology and Metabolism
    Volume306
    Issue number12
    DOIs
    StatePublished - Jun 15 2014

      Fingerprint

    Keywords

    • Adipose triglyceride lipase
    • Lipid droplet
    • Lipid metabolism
    • Lipolysis
    • Phosphorylation
    • Triglyceride

    ASJC Scopus subject areas

    • Endocrinology, Diabetes and Metabolism
    • Physiology
    • Physiology (medical)

    Cite this