Review - MicroRNAs: A new paradigm towards mechanistic insight of diseases.

In 1993 miRNAs were discovered during a research on Caenorhabditis elegans conducted by Victor Ambros and Gary Ruvkun. The gene lin-4 that played important role in development in C. elgans was observed not encoding any protein but a very small RNA molecule of just 22 nucleotides. Main objective of this review is to highlight the significance of miRNAs in regulating the expression of many genes, which are either directly or indirectly involved in many diseases. One of the major causes of illness and death in developed countries of the world is cardiovascular disease. Some of the miRNAs have certain role to play in heart that are not specified for heart. So miRNAs have been found to be in other tissues like fibroblasts, endothelial cells and smooth muscle cells that are part of physiological study of cardiovascular system. Adult heart has limited capacity of regeneration therefore lost cardiomyocytes due to myocardial ischemia or infarction can result in low performance of heart. miRNAs have been shown to play a role in apoptotic regulation of cardiomyocytes in vivo. Many studies have shown that miR146a and 155 are up regulated in peripheral blood mononuclear cells, synovial fibroblasts, synovial fluid and Th-17 cells from rheumatoid arthritis patients as compared to healthy persons. Several types of miRNAs are playing important roles in type 1 diabetes mellitus including miR-375 and miR-375 with intolerance to glucose and decreased beta cells account due to impaired proliferation. Up regulation of miR-125a in WAT of type 2 Diabetes mellitus have been observed. miRNAs have proved to be the important regulators of cytokines and growth factor expression. Thus, suggested as a good biomarker and target of therapy. miRNA profiling techniques have revealed the role of miRNAs in Multiple sclerosis.