A hypothesis for insulin resistance in primary human adipocytes involving MRTF-A and suppression of PPARγ

Björn Hansson, Sara Schumacher, Claes Fryklund, Björn Morén, Maria Björkqvist, Karl Swärd, Karin G. Stenkula

Research output: Contribution to journalArticlepeer-review

1 Citation (SciVal)


Obesity is the main risk factor behind insulin resistance and type 2 diabetes. Still, the mechanism behind adipocyte dysfunction is not yet resolved. Recently, we reported that rapid actin remodeling correlates with adipose cell size changes after short-term overfeeding. Therefore, we hypothesized that the actin-driven myocardin-related transcription factor (MRTF-A) contributes to impaired mature adipocyte function. Primary human adipocytes were subjected to adenoviral overexpression of MRTF-A or MRTF-B, followed by Western blot analysis and tracer glucose uptake assay. Further, we assessed cell size distribution, insulin response, MRTF-A localization, actin organization and degree of polymerization in adipocytes isolated from Ob/Ob mice. Overexpression of MRTF-A, but not MRTF-B, markedly suppressed PPARγ expression. Further, MRTF-A expression resulted in decreased IRS-1 level, shifted phosphorylation of Akt (pS473/pT308), IRS-1 (pS302) and AS160 (pT642), and lowered insulin-stimulated glucose uptake. Hypertrophic adipocytes from Ob/Ob mice displayed an increased proportion of polymerized actin, and increased nuclear translocation of MRTF-A compared with control (Ob/+). Similar with human adipocytes overexpressing MRTF-A, adipocytes isolated from Ob/Ob mice had reduced expression of IRS-1 and PPARγ, as well as impaired insulin response. Together, these data demonstrate that MRTF-A negatively influences insulin sensitivity and the expression of key targets in fully mature human adipocytes. This suggests that MRTF-A is poised to exert a transcriptional response in hypertrophic adipocytes, contributing to adipocyte dysfunction and insulin resistance.

Original languageEnglish
Pages (from-to)64-69
Number of pages6
JournalBiochemical and Biophysical Research Communications
Issue number1
Publication statusPublished - 2020 Nov 26

Subject classification (UKÄ)

  • Endocrinology and Diabetes


  • Adipocytes
  • Glucose transport
  • Insulin
  • Insulin signaling
  • MRTF-A
  • Obesity
  • PPARγ


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