Myokine irisin is a critical regulator of cognitive function I
Ontology highlight
ABSTRACT: 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: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.
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: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: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:Irisin, a recently identified myokine, is increased by exercise and plays pivotal roles in energy metabolism. However, it remains unknown whether irisin has any protective effects on Parkinson's disease. To examine the role of irisin in PD, irisin was peripherally delivered before or after the establishment of PD models by MPTP to explore its effect. We performed mRNA analysis in the midbrain of MPTP treated mice with irisin pre-treatment or delayed-treatment through RNA-Sequencing. And bioinformatic analysis was done on the identified deregulated genes through gene ontology (GO) analysis, KEGG pathway analysis and Gene set enrichment analysis (GSEA). Pathway analysis indicated that NAD(P)H activity and metabolism, PI3K-AKT pathway, MAPK pathway, inflammation-related signaling pathways played vital roles in the treatment of MPTP treated mice by irisin pre-treatment and irisin delayed treatment. This study provides a detailed analysis of the effects and underlying mechanisms of irisin treatment in MPTP treated mice.
Project description:BCI-838 is a pro-drug whose active metabolite BCI-632 is an antagonist at the group II metabotropic glutamate receptor (mGluR2/3). Hippocampal dentate gyrus of four-month old mouse model of AD amyloid pathology (APP/PS1) were investigated via transcriptomics analysis following BCI-838 treatment and physical exercise. Findings demonstrate up-regulated brain-derived neurotrophic factor (BDNF), PIK3C2A of the PI3K-MTOR pathway, and metabotropic glutamate receptors, and down-regulated EIF5A of ketamine-modulating mTOR activity. Our study points to BCI-838 as a safe and orally active compound capable of mimicking the beneficial effect of exercise on AHN, learning behavior, and anxiety in a mouse model of AD neuropathology.
Project description:Irisin, released from exercised muscle, has been shown to have beneficial effects on numerous tissues but its effects on bone are unclear. We found significant sex and genotype differences in bone from wildtype (WT) mice compared to mice lacking Fndc5 (KO), with and without calcium deficiency. Despite their bone being 2 indistinguishable from WT females, KO female mice were partially protected from osteocytic osteolysis and osteoclastic bone resorption when allowed to lactate or when placed on a low-calcium diet. Male KO mice have more but weaker bone compared to WT males, and when challenged with a low-calcium diet lost more bone than WT males. To begin to understand responsible molecular mechanisms, osteocyte transcriptomics was performed. Osteocytes from WT females had greater expression of genes associated with osteocytic osteolysis and osteoclastic bone resorption compared to WT males which had greater expression of genes associated with steroid and fatty acid metabolism. Few differences were observed between female KO and WT osteocytes, but with a low calcium diet, the KO females had lower expression of genes responsible for osteocytic osteolysis and osteoclastic resorption than the WT females. Male KO osteocytes had lower expression of genes associated with steroid and fatty acid metabolism, but higher expression of genes associated with bone resorption compared to male WT. In conclusion, irisin plays a critical role in the development of the male but not the female skeleton and protects male but not female bone from calcium deficiency. We propose irisin ensures the survival of offspring by targeting the osteocyte to provide calcium in lactating females, a novel function for this myokine.