Project description:Irisin is a recently identified myokine that is induced by exercise and stimulates brown-fat-like development of white fat and energy expenditure in humans and mice. In this study, we aimed to evaluate the pro-proliferative effect of irisin on C2C12 myoblasts and its mechanisms of action.
Project description:Identifying secreted mediators driving the cognitive benefits of exercise holds great promise for the treatment of cognitive decline in aging or Alzheimer’s disease (AD). Here, we show that irisin, the cleaved and circulating form of the exercise-induced membrane protein FNDC5, is sufficient to confer the exercise benefits on cognitive function. Genetic deletion of FNDC5/irisin (global F5KO mice) impairs cognitive function in exercise, aging, and AD. Diminished pattern separation in F5KOs can be rescued by delivering irisin directly into the dentate gyrus, suggesting that irisin is the active moiety. In F5KOs, adult-born neurons in the dentate gyrus are morphologically, transcriptionally, and functionally abnormal. Importantly, elevation of circulating irisin levels by peripheral administration, resulting in enrichment of central irisin, was sufficient to improve both the cognitive deficit and neuropathology in AD mouse models. Irisin is a crucial regulator of cognitive benefits of exercise and potential therapeutic for treating cognitive disorders including AD.
Project description:Identifying secreted mediators driving the cognitive benefits of exercise holds great promise for the treatment of cognitive decline in aging or Alzheimer’s disease (AD). Here, we show that irisin, the cleaved and circulating form of the exercise-induced membrane protein FNDC5, is sufficient to confer the exercise benefits on cognitive function. Genetic deletion of FNDC5/irisin (global F5KO mice) impairs cognitive function in exercise, aging, and AD. Diminished pattern separation in F5KOs can be rescued by delivering irisin directly into the dentate gyrus, suggesting that irisin is the active moiety. In F5KOs, adult-born neurons in the dentate gyrus are morphologically, transcriptionally, and functionally abnormal. Importantly, elevation of circulating irisin levels by peripheral administration, resulting in enrichment of central irisin, was sufficient to improve both the cognitive deficit and neuropathology in AD mouse models. Irisin is a crucial regulator of cognitive benefits of exercise and potential therapeutic for treating cognitive disorders including AD.
Project description:Identifying secreted mediators driving the cognitive benefits of exercise holds great promise for the treatment of cognitive decline in aging or Alzheimer’s disease (AD). Here, we show that irisin, the cleaved and circulating form of the exercise-induced membrane protein FNDC5, is sufficient to confer the exercise benefits on cognitive function. Genetic deletion of FNDC5/irisin (global F5KO mice) impairs cognitive function in exercise, aging, and AD. Diminished pattern separation in F5KOs can be rescued by delivering irisin directly into the dentate gyrus, suggesting that irisin is the active moiety. In F5KOs, adult-born neurons in the dentate gyrus are morphologically, transcriptionally, and functionally abnormal. Importantly, elevation of circulating irisin levels by peripheral administration, resulting in enrichment of central irisin, was sufficient to improve both the cognitive deficit and neuropathology in AD mouse models. Irisin is a crucial regulator of cognitive benefits of exercise and potential therapeutic for treating cognitive disorders including AD.
Project description:A pathological hallmark of Alzheimer’s disease (AD) is the deposition of amyloid-β protein (Aβ) in the brain. Physical exercise has been shown to reduce Aβ burden in various AD mouse models, but the underlying mechanisms have not been elucidated. Irisin, an exercise-induced hormone, is the secreted form of fibronectin-domain III containing 5 (FNDC5). Here, using a three-dimensional (3D) cell culture model of AD, we show that irisin significantly reduces Aβ pathology by increasing astrocytic release of the Aβ-degrading enzyme neprilysin (NEP). This is mediated by downregulation of ERK-STAT3 signaling. Finally, we show that integrin αV/β5 acts as the irisin receptor on astrocytes required for irisin-induced release of astrocytic NEP, leading to clearance of Aβ. Our findings reveal for the first time a cellular and molecular mechanism by which exercise-induced irisin attenuates Aβ pathology, suggesting a new target pathway for therapies aimed at the prevention and treatment of AD
Project description:Physical activity is thought to provide clinical benefit in Parkinson’s diseas (PD). Irisin is a blood-brain barrier permeable exercise-induced polypeptide secreted by muscle that mediates, in part, the beneficial effects of exercise. Here we show that irisin prevents pathologic -synuclein (-syn) induced neurodegeneration in the -syn preformed fibril mouse model of sporadic PD. Intravenous delivery of adenoviral irisin in vivo after the stereotaxic intrastriatal injection of -syn pre-formed fibrils reduced the formation of pathologic -syn and prevented the loss of dopamine neurons and reductions in striatal dopamine. Irisin also reduced the -syn pre-formed fibril induced motor deficits as assessed by the pole test and grip strength test. Administration of recombinant irisin in primary cortical neurons prevented pathologic -syn toxicity. Tandem mass spectrometry and biochemical analysis revealed that irisin reduced pathologic -syn by enhancing endolysosomal degradation of pathologic -syn. Our findings highlight the potential for therapeutic disease modification of irisin in PD.
Project description:Collectively, our study reveals that irisin can enhance chondrogenic differentiation of hMSCs via the Rap1/PI3K/AKT pathway, suggesting that irisin possesses prospects in cartilage regeneration. Collectively, our study reveals that irisin can enhance chondrogenic differentiation of hMSCs via the Rap1/PI3K/AKT pathway, suggesting that irisin possesses prospects in cartilage regeneration.
Project description:The v-erbA oncogene belongs to a superfamily of transcription factors called nuclear receptors, which includes the retinoic acid receptors (RARs) responsible for mediating the effects of retinoic acid (RA). Nuclear receptors bind to specific DNA sequences in the promoter region of target genes and v-erbA is known to exert a dominant negative effect on the activity of the RARs. The repressor activity of v-erbA has been linked to the development of hepatocellular carcinoma (HCC) in a mouse model. We have used microarray analysis to identify genes differentially expressed in hepatocytes in culture (AML12 cells) stably transfected with v-erbA and exposed to RA. We have found that v-erbA can affect expression of RA-responsive genes. We have also identified a number of v-erbA-responsive genes that are known to be involved in carcinogenesis and which may play a role in the development of HCC. Experiment Overall Design: AML12 control cells and v-erbA-transfected AML12 cells were exposed to 1 µM RA for 3h or 24h. Using microarray analysis, we compared gene expression in the presence and absence of v-erbA and identified RA-regulated genes differentially expressed in the presence of v-erbA.
Project description:Exercise benefits the human body in many ways. Irisin is secreted by muscle, increased with exercise, and conveys many physiological benefits, including improved cognition and resistance to neurodegeneration. Irisin acts via αV integrins; however, a mechanistic understanding of how small polypeptides like irisin can signal through integrins is poorly understood. Using mass spectrometry and cryo-EM, we demonstrate that extracellular heat-shock protein 90α (eHsp90α) is secreted by muscle with exercise and acts as a required cofactor that “opens” the integrin αVβ5 structure to allows for high affinity irisin binding and signaling through an eHsp90α/αV/β5 complex. By including hydrogen/deuterium exchange data, we generate and experimentally validate a 2.98 Å RMSD irisin/αVβ5 complex docking model. Irisin binds very tightly to an alternative interface on αVβ5 distinct from that involved in its interaction with known ligands. These data together elucidate a non-canonical mechanism by which a small polypeptide hormone like irisin can function through integrins.