Decreased caveolae in AGPAT2 lacking adipocytes is independent of changes in cholesterol or sphingolipid levels: A whole cell and plasma membrane lipidomic analysis of adipogenesis

Biochim Biophys Acta Mol Basis Dis. 2021 Sep 1;1867(9):166167. doi: 10.1016/j.bbadis.2021.166167. Epub 2021 May 12.

Abstract

Background: Adipocytes from lipodystrophic Agpat2-/- mice have impaired adipogenesis and fewer caveolae. Herein, we examined whether these defects are associated with changes in lipid composition or abnormal levels of caveolae-associated proteins. Lipidome changes were quantified in differentiated Agpat2-/- adipocytes to identify lipids with potential adipogenic roles.

Methods: Agpat2-/- and wild type brown preadipocytes were differentiated in vitro. Plasma membrane was purified by ultracentrifugation. Number of caveolae and caveolae-associated proteins, as well as sterol, sphingolipid, and phospholipid lipidome were determined across differentiation.

Results: Differentiated Agpat2-/- adipocytes had decreased caveolae number but conserved insulin signaling. Caveolin-1 and cavin-1 levels were equivalent between Agpat2-/- and wild type adipocytes. No differences in PM cholesterol and sphingolipids abundance were detected between genotypes. Levels of phosphatidylserine at day 10 of differentiation were increased in Agpat2-/- adipocytes. Wild type adipocytes had increased whole cell triglyceride, diacylglycerol, phosphatidylglycerol, phosphatidic acid, lysophosphatidylcholine, lysophosphatidylethanolamine, and trihexosyl ceramide, and decreased 24,25-dihydrolanosterol and sitosterol, as a result of adipogenic differentiation. By contrast, adipogenesis did not modify whole cell neutral lipids but increased lysophosphatidylcholine, sphingomyelin, and trihexosyl ceramide levels in Agpat2-/- adipocytes. Unexpectedly, adipogenesis decreased PM levels of main phospholipids in both genotypes.

Conclusion: In Agpat2-/- adipocytes, decreased caveolae is not associated with changes in PM cholesterol nor sphingolipid levels; however, increased PM phosphatidylserine content may be implicated. Abnormal lipid composition is associated with the adipogenic abnormalities of Agpat2 -/- adipocytes but does not prevent insulin signaling.

Keywords: Adipogenesis; Caveolae; Lipids; Lipodystrophy; Plasma membrane; agpat2.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyltransferases / metabolism*
  • Adipocytes / metabolism*
  • Adipogenesis / physiology*
  • Animals
  • Caveolae / metabolism*
  • Cell Membrane / metabolism*
  • Cholesterol / metabolism*
  • Insulin / metabolism
  • Lipid Metabolism / physiology
  • Lipidomics / methods
  • Lipids / physiology
  • Mice
  • Signal Transduction / physiology
  • Sphingolipids / metabolism*

Substances

  • Insulin
  • Lipids
  • Sphingolipids
  • Cholesterol
  • Acyltransferases
  • 2-acylglycerophosphate acyltransferase