MicroRNA Regulation of Endothelial Cell Secretion of Placental Growth Factor and Adipose Browning

Brown adipose tissue (BAT), a highly vascularized, thermogenic tissue, converts chemical energy into heat. The ability of BAT to expand based on the metabolic demand, known as plasticity, plays a critical role in the regulation of whole body energy balance. Endothelial cells (ECs) within the microvasculature of the adipose tissue play an important role in aiding BAT retain plasticity by actively modulating the angiogenic response. However, the mechanism of EC-adipocyte cross-talk during this process is not completely understood. In BAT ECs of obese mice, we have previously identified an anti-angiogenic microRNA, miR-409-3p, using a RNA-seq profiling approach. We now show that miR-409-3p targets MAP4K3 to confer its anti-angiogenic effects in ECs. Overexpression of miR-409-3p markedly decreased MAP4K3 expression in ECs, whereas inhibition of miR-409-3p had the opposite effects. SiRNA knockdown of MAP4K3 expression in ECs phenocopied the effects of miR-409-3p overexpression and significantly decreased cell proliferation and migration. Adipocytes co-cultured with conditioned media from ECs deficient in miR-409-3p showed increased expression of brown fat markers UCP1 and Cidea by RT-qPCR and Western. By multiplex ELISA, we identified a pro-angiogenic growth factor, Placental Growth Factor (PLGF), that is released from ECs in response to miR-409-3p deficiency. PLGF stimulation of 3T3-L1 adipocytes differentiated them into brown adipocytes. Furthermore, siRNA knockdown of MAP4K3 blocked the release of PLGF from ECs. Co-culturing conditioned media from ECs deficient in PLGF expression by siRNA silencing significantly decreased UCP1 expression in 3T3-L1 adipocytes, whereas conditioned media from ECs deficient both in miR-409-3p and PLGF further decreased UCP1 expression showing dependency for miR-409-3p regulated pathways. MiR-409-3p plays a key role in EC-BAT crosstalk by modulating PLGF, an effect that could be exploited for therapeutic intervention in obesity. Disclosure D. Perez-Cremades: None. D.R. Becker-Greene: None. H. Li: None. W. Wu: None. C.O. Aydogan: None. D. Ozdemir: None. M.W. Feinberg: None. B. Icli: None. Funding American Diabetes Association (1-16-JDF-046 to B.I.)