Background: Heat generation in UCP-1 active cells as present in brown adipose tissue contributes to the regulation of energy homeostasis. Brown adipose tissue is known to be present in neonates and infants and has recently also been demonstrated in children and adults. Interestingly, a transition of white adipocytes into a brown phenotype has been documented in vitro in mouse and human cells, yet the underlying mechanisms are still not resolved. Using transcriptome analysis comparing human white and brown adipocyte progenitor cells, we identified TENM2 as highly expressed in white progenitor cells.
Objective and hypotheses: To test whether TENM2 deficient preadipocytes convert into the brown/beige adipocyte lineage.
Method: Human SGBS preadipocytes were transfected with siRNA against human TENM2 or control siRNA two days before inducing adipogenic differentiation. Markers of adipogenesis and brown adipocyte marker genes were analysed using qRT-PCR and Western Blot. Mitochondrial mass was quantified by measuring citrate synthase activity.
Results: During the course of adipogenesis, the mRNA expression on TENM2 was high in preadipocytes and decreased to nearly undetectable levels in adipocytes. Using siRNA we achieved a TENM2 knockdown by 70% in preadipocytes. Both TENM2 knockdown and control cells differentiated equally well into adipocytes as shown by quantification of adipogenic differentiation rates and adipocyte marker gene expression (PPARg, GLUT4, FASN). Their mitochondrial mass was comparable. The expression of the brown adipocyte marker gene UCP1 was significantly higher in TENM2 knockdown cells (mRNA 3-fold, protein 4-fold vs control).
Conclusion: Our data show that the downregulation of TENM2 leads to the induction of a brown adipocyte phenotype. We therefore conclude that TENM2 is a candidate gene for pharmacological interventions aiming at an induction of brown adipogenesis.
10 - 12 Sep 2016
European Society for Paediatric Endocrinology