Reshaping the chromatin landscape in HUVECs from small-for-gestational-age newborns.

Small for gestational age (SGA), with increased risk of adult-onset cardiovascular diseases and metabolic syndromes, is known to associate with endothelial dysfunction, but the pathogenic mechanisms remain unclear. In this study, the pathological state of human umbilical vein endothelial cells (HUVECs) from SGA individuals was characterized by presenting increased angiogenesis, migration, proliferation, and wound healing ability relative to their normal counterparts. Genome-wide mapping of transcriptomes and open chromatins unveiled global gene expression alterations and chromatin remodeling in SGA-HUVECs. Specifically, we revealed increased chromatin accessibility at active enhancers, along with dysregulation of genes associated with angiogenesis, and further identified CD44 as the key gene driving HUVECs' dysfunction by regulating pro-angiogenic genes' expression and activating phosphorylated ERK1/2 and phosphorylated endothelial NOS expression in SGA. In SGA-HUVECs, CD44 was abnormally upregulated by 3 active enhancers that displayed increased chromatin accessibility and interacted with CD44 promoter. Subsequent motif analysis uncovered activating protein-1 (AP-1) as a crucial transcription factor regulating CD44 expression by binding to CD44 promoter and associated enhancers. Enhancers CRISPR interference and AP-1 inhibition restored CD44 expression and alleviated the hyperangiogenesis of SGA-HUVECs. Together, our study provides a foundational understanding of the epigenetic alterations driving pathological angiogenesis and offers potential therapeutic insights into addressing endothelial dysfunction in SGA.