STRUCTURE, MECHANISM, AND ROLE OF IRISIN IN CERTAIN PATHOLOGICAL DISORDERS

Abstract

In addition to being the primary storage site for glycogen, muscles release many myokines, mainly cytokines and chemokines that regulate growth, metabolism, and inflammatory responses such as IL-6, MCP-1, adiponectin, and irisin. Irisin is a novel myokine that is mainly expressed in muscles and adipose tissues, as well as the liver, heart, brain, thyroid, stomach, testes, cerebrospinal fluid, and other organs. It is a glycoprotein composed of 112 A.A residues with a molecular weight about 12 to 15 kD. Irisin production is stimulated through exercise, cold, dietary, and hormonal effects, where the expression of FNDC5 mRNA in the skeleton has been shown to increase after exercise. The AMPK-PGC-1-FNDC5 path is considered to be the main path of hormone synthesis through proteolysis of the FNDC5 molecule, which contains 209 residues of amino acids by the metalopeptidase enzyme family, where the irisin out-membrane part of FNDC5. There are currently no specific receptors for irisin, but it does its role by interacting with integrins, especially those integrin’s αV. This research aims to highlight the working mechanism of irisin and its role in many disorders as a potential therapeutic target for many neurological, bone, and metabolic disorders.