Detection of microRNAs in the regulation of parkin protein functioning in the response to lipotoxicity in rat pancreatic beta cell line (INS-1E)

Type 2 diabetes (T2D); is an endocrine and metabolic disorder characterized by peripheral insulin resistance and impaired insulin secretion from pancreatic beta (β) cells, causing hyperglycemia. Lipid and calcium homeostasis deteriorated as a result of problems in the Endoplasmic Reticulum (ER) and Mitochondrion (Mt), ER stress, Mt dysfunction, communication disorders between ER and Mt, disruption of autophagy mechanism, and in the T2D process; It manifests itself as insulin resistance and loss of pancreatic β-cell function. The product of the Park2 gene and the Parkin protein, which is an E3 ubiquitin-protein ligase, mediates autophagy and mitophagy, and at the same time, thanks to its ubiquitination ability; It plays an active role in DNA repair, transcription, translation, organelle traffic, proliferation, inflammation, and cell death/survival pathways. It is known that the Parkin protein supports cell survival through autophagy against lipotoxicity, which is one of the leading causes of insulin resistance and T2D. In the absence of the Parkin protein, the cell tends to apoptosis. In minimal lipotoxicity differences, rapid changes occur in the expression level of the Park2 gene and the function of the protein. This has led to the hypothesis that Parkin protein regulation may be regulated by microRNAs (miRNAs) that are members of the fast-acting RNA interference (RNAi) mechanism. Based on this, in this thesis study, bioinformatics approaches and experimental analyzes were used together and miRNA expression differences in pancreatic β cells in the presence of Parkin protein in lipotoxic conditions induced by palmitic acid (PA), has been studied which causes organelle stress in ER and Mt, and in conditions where the Park2 gene was silenced by siRNA. As a result of miRNA profiling and further bioinformatic analyzes and validation studies, miRNAs thought to be involved in the regulation of Parkin protein, which has a role in cell survival, are rno-miR-344a-5p, rno-miR- 96-5p, rno-miR-153-3p, and rno-miR-30e-3p. These miRNAs have been shown to be particularly active in cell survival, autophagy, apoptosis, T2D, and insulin signaling pathways. qRT- PCR studies for the validation of the expressions of the genes targeted by the candidate miRNAs also support the regulatory roles of the selected miRNAs in this process.