Proteomic analysis of glucose-induced cardiac myoblasts and the potential role of miR-92b-5p in regulating sarcomere proteins under hyperglycemic environment.

BACKGROUND: Diabetes mellitus, a co mMon metabolic disorder that causes high blood glucose, is due to impaired insulin secretion. Prolonged high blood sugar is associated with heart disease. Many proteins involved in metabolic pathways and contractility of cardiac cells regulate cardiac hypertrophy, altering normal cardiac physiology and function. Moreover, microRNAs are essential regulators of these proteins. Thus, there is a need to study the protein and microRNA alterations in cardiomyocytes to better understand the mechanisms activated during cardiac stress.

OBJECTIVE: The study aims to profile differentially expressed sarcomere proteins in H9C2 cell lines under high glucose conditions compared to normal conditions, along with identification of miRNAs regulating these proteins.

METHODS: Cardiac myoblast cell lines were treated with D-Glucose at three concentrations (10 mM, 25 mM, and 50 mM). Total cell protein analyzed by Tandem Mass spectrometry Nano LC-MS/MS. Furthermore, next generation sequencing data were analyzed for detecting microRNAs regulating cardiac cell protein expression. Bioinformatics databases such as Uniprot, Ingenuity Pathway analysis (IPA), PANTHER, and Target scan were used.

RESULTS: The Nano LC-MS/MS analysis showed 2891 protein, 1351 protein groups, and 4381 peptide groups in both glucose treated and control samples. Most proteins were metabolite interconversion enzymes, translation proteins, and proteins regulating the cytoskeleton. IPA analysis revealed differentially expressed proteins involved in EIF2 signaling, actin cytoskeleton signaling, cardiac fibrosis, and cell death. Moreover, the proteins troponin, tropomyosin, myosin, alpha-actin, and ATP synthase were found to be downregulated, thus responsible for altering sarcomere protein expression. Rno-mir-92b-5p was observed to be highly upregulated at 50 mM. Its target genes namely TPM2, ATP1A2, and CORO1C were mostly components of the sarcomere complex and its regulators.

CONCLUSION: A combination of proteomic profile and microRNA profile of hyperglycemic cells provides an insight for advanced therapeutics. Our study has highlighted the role of sarcomere proteins, activation of Eukaryotic Initiation Factor 2 (eIF2) signaling and suppression of actin cytoskeleton signaling in pathophysiology of cardiomyopathy. MiR-92b-5p has an important role in regulating sarcomere protein complex activated.