PRDM16 controls smooth muscle cell fate in atherosclerosis [RNA-Seq]

Vascular smooth muscle cells (SMCs) normally exist in a contractile state but can undergo fate switching to produce a variety of cell phenotypes in response to pathologic stimuli. In atherosclerosis, these phenotypically modulated SMCs play a critical role in determining plaque composition and the risk of major adverse cardiovascular events. We found that PRDM16, a transcription factor that has been genetically implicated in cardiovascular disease, is highly expressed in arterial SMCs, and downregulated during SMC fate switching in human and mouse atherosclerosis. Deletion of Prdm16 in SMCs of mice activates the synthetic modulation program in arteries under homeostatic conditions. Upon exposure to atherogenic conditions, these mice form strikingly dense, SMC-rich, fibroproliferative plaques that contain few foam cells. Acute deletion of Prdm16 in SMCs triggers a similar fibrotic response, resulting in the formation of collagen-rich lesions with thick fibrous caps – a hallmark of enhanced lesion stability. Reciprocally, ectopic expression of PRDM16 in cultured cells is sufficient to block SMC synthetic processes, including migration, proliferation, and fibrosis. Mechanistically, PRDM16 binds to chromatin and decreases activating histone marks at synthetic genes. Altogether, our results define PRDM16 as a specific gatekeeper of the synthetic SMC switch and reveal that PRDM16 levels in SMCs predetermine atherogenic lesion composition.