Activin B inhibits lipolysis in 3T3-L1 adipocytes

• Activin B, consisting of two inhibin betaB (INHBB) subunits, is a hormone known to affect gonadal function, reproduction and fetal development. We have reported that INHBB and activin B receptors are highly expressed in adipocytes suggesting that activin B may have local effects in adipose tissue. In this study, we investigate the effect of activin B on lipolysis, measured as release of non-esterified fatty acids and free glycerol. Recombinant activin B decreased lipolysis in a concentration-dependent manner and increased intracellular triglyceride content in 3T3-L1 adipocytes. siRNA-mediated knock down of INHBB expression increased lipolysis, and this effect was abolished by addition of recombinant activin B. In line with its inhibitory effect on lipolysis, activin B caused a down regulation of the expression of adipose triglyceride lipase and hormone sensitive lipase, key genes involved in lipolysis. In summary, we suggest that activin B is a novel adipokine that inhibits lipolysis in a paracrine or autocrine manner.

Nyckelord

Activin B; lipolysis; adipocytes

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