MicroRNA-99 determines the Fate of Cardiac Hypertrophy and Heart Failure
Subbiah Ramasamy,
Assistant Professor,
Madurai Kamaraj University
The physiological cardiac hypertrophy is an adaptive condition without myocyte cell death, while pathological hypertrophy is a maladaptive condition associated with myocyte cell death. A2M, an acute phase protein induces cardiac hypertrophy via ERK1, 2 and PI3K/Akt signaling. This study explores the miRNome of A2M induced hypertrophied cardiomyocytes and the role of miRNA-99 family in cardiac hypertrophy. Physiological and pathological cardiac hypertrophy was induced in H9c2 cell lines using A2M and isoproterenol respectively. Total RNA isolation and small RNA sequencing were executed for physiological hypertrophy model. The differentially expressed miRNAs and its target mRNAs were validated by qPCR and western blotting. Subsequently, the selected miRNA was functionally characterized by overexpression and silencing. Analysis of small RNA reads revealed the differential expression of a large set of miRNAs during hypertrophy, of which miR-99 family was highly downregulated upon A2M treatment. ChIP-PCR confirms the binding of Egr-1 transcription factor to the miR-99 promoter. Further, siRNA-mediated silencing of Egr-1 decreased the expression pattern of miR-99. The overexpression or silencing of miR-99 diverges the physiological hypertrophy to pathological hypertrophy and vice versa by regulating Akt pathway. The results proved Egr-1 mediated regulation of miR-99 family. Upregulated miR-99 expression during pathological hypertrophy suggests that it can be a valuable diagnostic marker for heart failure.
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