Abstract Circular RNAs (circRNAs) are generated by back-splicing and control cellular signaling and phenotypes. Pericytes stabilize the capillary structure and play an important role in the formation and maintenance of new blood vessels. Here, we characterized hypoxia-regulated circRNAs in human pericytes and showed that circPLOD2 is induced by hypoxia and regulates pericyte function. Silencing of circPLOD2 increased pericyte proliferation, endothelial-pericyte interaction and tube formation. Transcriptional profiling of circPLOD2-depleted cells and epigenomic analyses revealed widespread changes in gene expression and identified the circPLOD2-dependent regulation of the transcription factor KLF4 as a key effector of these changes. Importantly, overexpression of KLF4 was sufficient to reverse the effects on pericyte proliferation and endothelial-pericyte interactions observed after circPLOD2 depletion. Together, these data revealed a novel function of circPLOD2 in the control of pericyte proliferation and capillary formation and showed that circPLOD2-mediated regulation of KLF4 significantly contributes to the transcriptional response to hypoxia. Highlights circPLOD2 is upregulated in hypoxia in human vascular pericytes Selective depletion of circPLOD2, but not linear PLOD2 mRNA, changes pericyte migration and endothelial-pericyte interaction circPLOD2 depletion triggers widespread changes in gene expression that are mirrored in the transcriptional hypoxia response Epigenomic analyses pinpoint the transcription factor KLF4 as a central player in circPLOD2-mediated expression changes KLF4 overexpression is sufficient to rescue the changes in pericyte function caused by circPLOD2 depletion

Circular RNA circPLOD2 regulates pericyte function by targeting the transcription factor KLF4