(DCP006) DIABETES INDUCED CIRCRNA_012164 AND MICRORNA-9-5P EXPRESSION IN CARDIAC ENDOTHELIAL CELLS REGULATE DIABETIC CARDIAC FIBROSIS

Background: Diabetic cardiac myopathy (DCM) is a potent and independent risk factor in developing cardiovascular disease and heart failure. Despite successful management of comorbid cardiovascular risks, diabetic patients still see increased incidents of heart failure. Hyperglycemia damages endothelial cells, resulting in signaling derangement and altered gene expression. These changes in endothelial cells promotes inflammatory signaling and the excessive production of extracellular matrix proteins into the basement membrane, resulting in cardiac fibrosis (CF). CF results in cardiac remodeling and hypertrophy, ultimately ending in heart failure. Previous research has shown that the noncoding RNA (ncRNA) MicroRNA-9-5p (miR9) is affected by changes in blood glucose and regulates the expression of various fibrotic and inflammatory genes related to DCM. CircularRNAs are a new class of ncRNA which function by sponging up and downregulating microRNAs. CircRNA_012164 is a circRNA which has been found by an assay to be upregulated in diabetic murine heart tissue and has a binding affinity to miR9. We hypothesize that circRNA_012164 interacts with miR9 to mediate the expression of genes associated with cardiac fibrosis in diabetes.

METHODS AND RESULTS: We induced diabetes in normal and endothelial-specific miR9-overexpressing mice to quantify the downstream effects of hyperglycemia and miR9 on the expression levels of fibrotic genes and circRN_012164. CircRNA will be quantified following digestion of linear RNA with RNase. Next, we assessed the expression of circRNA_012164 in mouse cardiovascular endothelial cells (MCECs) to observe the endothelial-specific expression of circRNA_012164 in response to hyperglycemic and normoglycemic conditions. Finally, we will establish a causational relationship between circRNA_012164, miR9 and downstream fibrotic genes with transfection experiments.
Our results show that endothelial-specific miR9-overexpressing mice show significantly reduced expression of FN1, Col1A1 and FSP1 in both diabetic and non-diabetic mice, with miR9 overexpression being able to restore gene expression to baseline non-diabetic levels. CircRNA_012164 was confirmed to be overexpressed in diabetic murine hearts. In MCECs, hyperglycemia resulted in an increase in

Conclusion: Though a relatively newly classified ncRNA, the role of circRNA in disorders that present with metabolic memory shows promise for future research. circRNA_012164 expression is tissue specific and relatively abundant, and circRNAs are resistant to exonuclease degradation, indicating its potential as a biomarker of disease and a therapeutic target.