Role of irisin in physiology and pathology

Abstract

Irisin, out-membrane part of fibronectin type III domain–containing 5 protein (FNDC5), was activated by Peroxisome proliferator-activated receptor γ (PPARγ) coactivator-1α (PGC-1α) during physical exercise in skeletal muscle tissues. Most studies have reported that the concentration of irisin is highly associated with health status. For instance, the level of irisin is significantly lower in patients with obesity, osteoporosis/fractures, muscle atrophy, Alzheimer’s disease, and cardiovascular diseases (CVDs) but higher in patients with cancer. Irisin can bind to its receptor integrin αV/β5 to induce browning of white fat, maintain glucose stability, keep bone homeostasis, and alleviate cardiac injury. However, it is unclear whether it works by directly binding to its receptors to regulate muscle regeneration, promote neurogenesis, keep liver glucose homeostasis, and inhibit cancer development. Supplementation of recombinant irisin or exercise-activated irisin might be a successful strategy to fight obesity, osteoporosis, muscle atrophy, liver injury, and CVDs in one go. Here, we summarize the publications of FNDC5/irisin from PubMed/Medline, Scopus, and Web of Science until March 2022, and we review the role of FNDC5/irisin in physiology and pathology.

Changes in the concentration of bone turnover markers in men after maximum intensity exercise

“…The level of physical activity is another factor that may influence variation in the level of bone alkaline phosphatase (b-ALP) activity in response to physical exercise ( Liu et al, 2022 ), which could also be observed in our study. However, in research conducted by Colaianni et al (2014) , it was proved that after 3 weeks of induced exercise, there is an increased differentiation of osteoblasts in vitro compared to resting conditions, which would indicate a positive effect of irisin visible during physical exercise by working muscles on bone tissue ( Colaianni et al, 2014 ).…”

Effects of recreational SCUBA diving practiced once a week on neurohormonal response and myokines-mediated communication between muscles and the brain

“…FNDC5 expression is under the control of the peroxisome proliferator-activated receptor γ coactivator 1-α (PGC1α), a metabolism regulator, thus irisin secreted from myocytes promotes mitochondrial biogenesis (58), whereas, in white adipose tissue (WAT), it promotes browning response and thermogenesis (59). Several studies showed increased irisin levels after exercise, suggesting positive effects of exercise on cardiovascular, skeletal, and muscular systems (60,61). However, some other studies observed a decrease in irisin levels after various types of physical activity (62)(63)(64)(65)(66) whereas some others reported no changes in irisin levels in different exercise programmes (67,68).…”

Irisin and Bone in Sickness and in Health: A Narrative Review of the Literature

“…Irisin is a myokine with multi-faceted actions in energy metabolism in physiological and pathological conditions [136], and emerging data have highlighted its role on the muscle-bone axis in particular (Figure 1). Recent evidence suggests that irisin acts on target cells, including bone cells [11].…”