A microRNA cluster controls fat cell differentiation and adipose tissue expansion by regulating SNCG

The H19X-encoded miR-424(322)/503 cluster regulates multiple cellular functions. Here we report for the first time that it is also a critical linchpin of fat mass expansion. Deletion of this miRNA cluster in mice results in obesity, while increasing the pool of early adipocyte progenitors and hypertrophied adipocytes. Complementary loss and gain of function experiments and RNA sequencing demonstrate that miR-424(322)/503 regulates a conserved genetic program involved in the differentiation and commitment of white adipocytes. Mechanistically, we demonstrate that miR-424(322)/503 targets ?-Synuclein (SNCG), a factor that mediates this program rearrangement by controlling metabolic functions in fat cells, allowing adipocyte differentiation and adipose tissue enlargement. Accordingly, diminished miR-424(322) in mice and obese humans co-segregates with increased SNCG in fat and peripheral blood as mutually exclusive features of obesity, being normalized upon weight loss. Our data unveil a previously unknown regulatory mechanism of fat mass expansion tightly controlled by the miR-424(322)/503 through SNCG. Overall design: Mouse embryonic fibroblasts (MEFs) were isolated from wild-type (Wt) and miR-424(322)/503-/- (miR-KO) E14 embryos and differentiated into adipocytes. RNA sequencing was conducted in adipocyte precursor cells (PA) and in Wt and miR-KO fully-differentiated lipid-containing mature adipocytes (MA). Cryopreserved human subcutaneous preadipocytes carrying a doxycycline (Dox)-inducible pTRIPz lentiviral system were cultured and differentiated according to manufacturer's instructions. RNA sequencing was conducted in differentiated adipocytes overexpressing (OE) the miR-424(322)/503 cluster during differentiation (14d) or for last 2 days of the adipogenic course (48h) vs respective non-targeting controls (NTC) under same conditions of cell culture and treatment.