REGION-SPECIFIC GENE EXPRESSION AND SEX INFORM ABOUT DISEASE SUSCEPTIBILITY IN THE AORTA - MCAM Knockdown

Pathology in large vessels frequently develops at specific locations, implying that local stressors and spatially restricted gene expression are likely contributors to disease susceptibility. To identify site- and sex-specific differences that could inform about vulnerability, we performed single-cell transcriptomics in the carotids, aortic arch, thoracic, and abdominal aorta. Our findings revealed: (1) regionally defined transcriptional profiles, (2) signatures associated with embryonic origins, and (3) differential contributions of sex-specific effectors. Sex differences were predominantly observed in the thoracic and abdominal aorta. MCAM/CD146, a transcript with sex-skewed expression in vSMC of the abdominal aorta showed a 2.5-fold lower expression in males when compared to females. siRNA knockdown was performed to identify downstream targets of MCAM in vascular smooth muscle cells and to assess if sex affected number and biological function of genes modulated by changes in MCAM expression. MCAM was found to be further downregulated in vSMC associated with aortic aneurysms in humans. The findings reveal underlying diversity within vSMC populations with relevance to understanding site-specific and sex-specific variation of vascular pathologies.