The transcription elongation factors Spt4 and Spt6 promote dermal adipocyte differentiation

Regulation of adipogenesis has classically been viewed through the lens of transcription initiation driven by lineage defining transcription factors. In this study, we uncover transcription elongation as a critical and previously underappreciated regulatory layer controlling adipocyte cell fate. We demonstrate that the elongation factors Spt4 and Spt6 are indispensable for adipogenic differentiation, as their depletion severely impairs adipogenic gene induction and perilipin expression. Spt4 and Spt6 directly regulate the genes coding for core adipogenic transcription factors, including Cebpa, Pparg, Krox20, and Stat3, by promoting RNA polymerase II (Pol II) progression through their gene bodies. In the absence of these factors, Pol II becomes stalled at the transcriptional start sites of these adipogenic genes. These data support a post transcription initiation requirement for Spt4 and Spt6 in productive elongation rather than promoter loading. Our findings identify transcription elongation control as a key determinant of adipogenic fate.