Downregulation of TCF19 and ATAD2 causes endothelial cell cycle arrest at the transition from cardiac hypertrophy to heart failure.

Cardiac hypertrophy is a key mechanism that allows the heart to adapt to increased load, but in the long term is associated with a higher risk for heart failure, arrhythmia, and death. During hypertrophic growth, cardiac myocytes signal to endothelial cells via vascular endothelial growth factor (VEGF) to promote angiogenesis and maintain myocardial oxygen supply. Insufficient angiogenesis leads to a decline in capillary density and drives the progression from compensated cardiac hypertrophy to heart failure. Here, we studied the time course of endothelial cell gene expression during heart failure development and identified transcriptional regulators of cell proliferation and angiogenesis. We applied transverse aortic constriction (TAC) in mice and isolated cardiac endothelial cells for RNA sequencing after 6 h and 1, 3, 7, or 28 days to create an inventory of gene expression during the course of cardiac hypertrophy and failure. Echocardiography revealed that decompensated heart failure occurred between days 7 and 28 after TAC. At the same time, we observed a switch in endothelial cell gene expression with an upregulation of proliferation markers in the hypertrophy state but downregulation in decompensated heart failure. Of note, endothelial cell cycle arrest occurred despite strong VEGF signaling from cardiac myocytes, indicating VEGF resistance. To investigate how endothelial cell proliferation is transcriptionally regulated, we performed a weighted gene co-expression network analysis and identified a module of 180 cell cycle-related genes. We predicted transcription factor 19 (TCF19), ATPase family AAA domain containing 2 (ATAD2), and transcription factor Dp-1 (TFDP1) to be central regulators of this gene module. Knockdown of TCF19 and ATAD2 by siRNA in HUVECs led to a downregulation of the marker of proliferation MKI67 and repressed cell proliferation, tube formation, and cell migration, confirming their regulatory function. In heart tissue biopsies from patients with aortic stenosis, TCF19 and ATAD2 abundance were positively correlated with endothelial cell proliferation. TCF19 or ATAD2 control the expression of a gene network involved in endothelial cell proliferation and angiogenesis. Downregulation of TCF19 and ATAD2 is associated with endothelial cell cycle arrest and an impaired angiogenic response to VEGF signaling that may promote the transition from compensated cardiac hypertrophy to heart failure.