Microarray analysis and functional characterization revealed NEDD4-mediated cardiomyocyte autophagy induced by angiotensin II.

Autophagy is a highly regulated intracellular process to maintain cellular homeostasis by degrading damaged proteins and organelles. Dysregulation of autophagic activity in cardiomyocytes is implicated in various heart diseases. However, the underlying mechanisms of cardiomyocyte autophagy are not yet known. In this study, the enhanced cardiomyocyte autophagy was induced by angiotensin II (0.1 μmol/L), demonstrated by the increase of double-membraned autophagosomes, BECN1 expression, and the conversion of LC3-I to LC3-II. Microarray assay showed that a total of 197 genes were differentially expressed in angiotensin II-treated cardiomyocytes, including 22 upregulated and 175 downregulated. Gene ontology functional enrichment analysis showed that nearly 50% of differentially expressed genes were related to metabolism and energy maintenance in biological process. Pathway analysis showed that most frequently represented pathways were involved in metabolism and the citric acid cycle and respiratory electron transport. Based on KEGG database, 10 differentially expressed genes were found to be involved in autophagic signaling pathways. The hub genes with high degree were predicted to regulate cardiomyocyte autophagy activity by PPI network analysis. NEDD4, the top focus hub gene, showed a clear time-dependent increased expression pattern in cardiomyocytes during angiotensin II treatment. Moreover, inhibition of NEDD4 could significantly reduce cardiomyocyte autophagy induced by angiotensin II. In summary, the cardiomyocyte autophagy-related genes were screened by microarray assay combining with bioinformatics analysis. The role of NEDD4 on cardiomyocyte autophagy might provide valuable clues to finding therapeutic targets for heart diseases.