EH Domain-Containing 2 Deficiency Restricts Adipose Tissue Expansion and Impairs Lipolysis in Primary Inguinal Adipocytes

Claes Fryklund; Björn Morén; Shrenika Shah; Mario Grossi; Eva Degerman; Claudia Matthaeus; Karin G Stenkula

doi:10.3389/fphys.2021.740666

EH Domain-Containing 2 Deficiency Restricts Adipose Tissue Expansion and Impairs Lipolysis in Primary Inguinal Adipocytes

Front Physiol. 2021 Sep 24:12:740666. doi: 10.3389/fphys.2021.740666. eCollection 2021.

Authors

Claes Fryklund¹, Björn Morén¹, Shrenika Shah², Mario Grossi¹, Eva Degerman¹, Claudia Matthaeus³, Karin G Stenkula¹

Affiliations

¹ Department of Experimental Medical Science, Lund University, Lund, Sweden.
² School of Biomedical, Nutritional and Sport Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom.
³ National Heart, Lung and Blood Institute, NIH, Bethesda, MD, United States.

Abstract

Lipid uptake can be facilitated via caveolae, specific plasma membrane invaginations abundantly expressed in adipocytes. The dynamin-related protein EH domain-containing 2 (EHD2) stabilizes caveolae at the cell surface. Here, we have examined the importance of EHD2 for lipid handling using primary adipocytes isolated from EHD2 knockout (Ehd2^-/- ) C57BL6/N mice. Following high-fat diet (HFD) feeding, we found a clear impairment of epididymal, but not inguinal, adipose tissue expansion in Ehd2^-/- compared with Ehd2^+/+ (WT) mice. Cell size distribution analysis revealed that Ehd2^-/- mice had a lower proportion of small adipocytes, and an accumulation of medium-sized adipocytes in both epididymal and inguinal adipose tissue. Further, PPARγ activity, FABP4 and caveolin-1 expression were decreased in adipocytes isolated from Ehd2^-/- mice. Inguinal adipocytes isolated from Ehd2^-/- mice displayed reduced lipolysis in response to beta adrenergic receptor agonist, which was associated with reduced phosphorylation of perilipin-1 and hormone sensitive lipase (HSL). This impairment could not be rescued using a cAMP analog, indicating that impaired lipolysis in Ehd2^-/- primary adipocytes likely occurs at the level of, or downstream of, protein kinase A (PKA). Altogether, these findings pinpoint the importance of EHD2 for maintained intracellular lipid metabolism, and emphasize differences in mechanisms regulating lipid handling in various adipose-tissue depots.

Keywords: EH domain-containing 2; adipocytes; adipose tissue; caveolae; fatty acids.