Role and Functions of Irisin: A Perspective on Recent Developments and Neurodegenerative Diseases

Irisin is a peptide derived from fibronectin type III domain-containing protein 5 (FNDC5) and is primarily produced by muscle fibers under the regulation of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) during exercise. Irisin has been the subject of extensive research due to its potential as a metabolic regulator and its antioxidant properties. Notably, it has been associated with protective actions within the brain. Despite growing interest, many questions remain regarding the molecular mechanisms underlying its effects. This review summarizes recent findings on irisin, highlighting its pleiotropic functions and the biological processes and molecular cascades involved in its action, with a particular focus on the central nervous system. Irisin plays a crucial role in neuron survival, differentiation, growth, and development, while also promoting mitochondrial homeostasis, regulating apoptosis, and facilitating autophagy-processes essential for normal neuronal function. Emerging evidence suggests that irisin may improve conditions associated with non-communicable neurological diseases, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, frontotemporal dementia, and multiple sclerosis. Given its diverse benefits, irisin holds promise as a novel therapeutic agent for preventing and treating neurological diseases.