The Effect of Hypoxia on Irisin Expression in HL-1 Cardiomyocytes.

Abstract

Cardiovascular diseases (CVD) are the leading cause of death worldwide. In 2019, 523 million people were diagnosed with CVD, with 18.6 million deaths. Improved treatment and diagnostics could reduce CVD's impact. Irisin (Ir) is crucial for heart function and may be a biomarker for heart attack. Ir is a glycoprotein with sugar residues attached to its protein structure. This glycosylation affects Ir stability, solubility, and receptor interactions on target cells. Its secondary structure includes a fibronectin type III domain, essential for its biological functions. Ir helps cardiomyocytes to respond to hypoxia and protects mitochondria. The aim of the study was to determine the FNDC5 gene expression level and the Ir level in HL-1 cardiomyocytes subjected to hypoxia. We examined the effect of hypoxia on the expression levels of the FNDC5 gene and those of Ir in mouse cardiomyocytes of the HL-1 cell line. Real-time PCR (RT-PCR) was used to estimate the expression levels of the FNDC5 gene. Western blot and immunofluorescence methods were used to analyze the Ir protein levels. Analyses showed an increased Ir level in HL-1 cardiomyocytes in response to hypoxia. This is the first study to confirm the presence of Ir in HL-1 cells. The observed increase in Ir expression in murine cardiomyocytes is associated with the hypoxic environment and can be potentially used to diagnose hypoxia and CVD.