Publications by authors named "Shogo Wada"

18 Publications

  • Page 1 of 1

Noncanonical WNT Activation in Human Right Ventricular Heart Failure.

Front Cardiovasc Med 2020 7;7:582407. Epub 2020 Oct 7.

Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States.

No medical therapies exist to treat right ventricular (RV) remodeling and RV failure (RVF), in large part because molecular pathways that are specifically activated in pathologic human RV remodeling remain poorly defined. Murine models have suggested involvement of Wnt signaling, but this has not been well-defined in human RVF. Using a candidate gene approach, we sought to identify genes specifically expressed in human pathologic RV remodeling by assessing the expression of 28 WNT-related genes in the RVs of three groups: explanted nonfailing donors (NF, = 29), explanted dilated and ischemic cardiomyopathy, obtained at the time of cardiac transplantation, either with preserved RV function (pRV, = 78) or with RVF ( = 35). We identified the noncanonical WNT receptor ROR2 as transcriptionally strongly upregulated in RVF compared to pRV and NF (Benjamini-Hochberg adjusted < 0.05). ROR2 protein expression correlated linearly to mRNA expression ( = 0.41, = 8.1 × 10) among all RVs, and to higher right atrial to pulmonary capillary wedge ratio in RVF ( = 0.40 = 3.0 × 10). Utilizing Masson's trichrome and ROR2 immunohistochemistry, we identified preferential ROR2 protein expression in fibrotic regions by both cardiomyocytes and noncardiomyocytes. We compared RVF with high and low ROR2 expression, and found that high ROR2 expression was associated with increased expression of the WNT5A/ROR2/Ca responsive protease calpain-μ, cleavage of its target FLNA, and FLNA phosphorylation, another marker of activation downstream of ROR2. ROR2 protein expression as a continuous variable, correlated strongly to expression of calpain-μ ( = 0.25), total FLNA ( = 0.67), calpain cleaved FLNA ( = 0.32) and FLNA phosphorylation ( = 0.62, < 0.05 for all). We demonstrate robust reactivation of a fetal WNT gene program, specifically its noncanonical arm, in human RVF characterized by activation of ROR2/calpain mediated cytoskeleton protein cleavage.
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http://dx.doi.org/10.3389/fcvm.2020.582407DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7575695PMC
October 2020

The small intestine shields the liver from fructose-induced steatosis.

Nat Metab 2020 07 22;2(7):586-593. Epub 2020 Jun 22.

Department of Chemistry and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA.

Per capita fructose consumption has increased 100-fold over the last century. Epidemiological studies suggest that excessive fructose consumption, and especially consumption of sweet drinks, is associated with hyperlipidaemia, non-alcoholic fatty liver disease, obesity and diabetes. Fructose metabolism begins with its phosphorylation by the enzyme ketohexokinase (KHK), which exists in two alternatively spliced forms. The more active isozyme, KHK-C, is expressed most strongly in the liver, but also substantially in the small intestine where it drives dietary fructose absorption and conversion into other metabolites before fructose reaches the liver. It is unclear whether intestinal fructose metabolism prevents or contributes to fructose-induced lipogenesis and liver pathology. Here we show that intestinal fructose catabolism mitigates fructose-induced hepatic lipogenesis. In mice, intestine-specific KHK-C deletion increases dietary fructose transit to the liver and gut microbiota and sensitizes mice to fructose's hyperlipidaemic effects and hepatic steatosis. In contrast, intestine-specific KHK-C overexpression promotes intestinal fructose clearance and decreases fructose-induced lipogenesis. Thus, intestinal fructose clearance capacity controls the rate at which fructose can be safely ingested. Consistent with this, we show that the same amount of fructose is more strongly lipogenic when drunk than eaten, or when administered as a single gavage, as opposed to multiple doses spread over 45 min. Collectively, these data demonstrate that fructose induces lipogenesis when its dietary intake rate exceeds the intestinal clearance capacity. In the modern context of ready food availability, the resulting fructose spillover drives metabolic syndrome. Slower fructose intake, tailored to intestinal capacity, can mitigate these consequences.
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http://dx.doi.org/10.1038/s42255-020-0222-9DOI Listing
July 2020

Functional effects of muscle PGC-1alpha in aged animals.

Skelet Muscle 2020 05 6;10(1):14. Epub 2020 May 6.

Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.

PGC-1 (peroxisome-proliferator-activated receptor-γ coactivator-1) alpha is a potent transcriptional coactivator that coordinates the activation of numerous metabolic processes. Exercise strongly induces PGC-1alpha expression in muscle, and overexpression of PGC-1alpha in skeletal muscle activates mitochondrial oxidative metabolism and neovascularization, leading to markedly increased endurance. In light of these findings, PGC-1alpha has been proposed to protect from age-associated sarcopenia, bone loss, and whole-body metabolic dysfunction, although these findings have been controversial. We therefore comprehensively evaluated muscle and whole-body function and metabolism in 24-month-old transgenic mice that over-express PGC-1alpha in skeletal muscle. We find that the powerful effects of PGC-1alpha on promoting muscle oxidative capacity and protection from muscle fatigability persist in aged animals, although at the expense of muscle strength. However, skeletal muscle PGC-1alpha does not prevent bone loss and in fact accentuates it, nor does it have long-term benefit on whole-body metabolic composition or insulin sensitivity. Protection from sarcopenia is seen in male animals with overexpression of PGC-1alpha in skeletal muscle but not in female animals. In summary, muscle-specific expression of PGC-1alpha into old age has beneficial effects on muscle fatigability and may protect from sarcopenia in males, but does not improve whole-body metabolism and appears to worsen age-related trabecular bone loss.
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http://dx.doi.org/10.1186/s13395-020-00231-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7201623PMC
May 2020

Investigation of a dilated cardiomyopathy-associated variant in BAG3 using genome-edited iPSC-derived cardiomyocytes.

JCI Insight 2019 11 14;4(22). Epub 2019 Nov 14.

Division of Cardiology and Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.

Mutations in B cell lymphoma 2-associated athanogene 3 (BAG3) are recurrently associated with dilated cardiomyopathy (DCM) and muscular dystrophy. Using isogenic genome-edited human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs), we examined how a DCM-causing BAG3 mutation (R477H), as well as complete loss of BAG3 (KO), impacts myofibrillar organization and chaperone networks. Although unchanged at baseline, fiber length and alignment declined markedly in R477H and KO iPSC-CMs following proteasome inhibition. RNA sequencing revealed extensive baseline changes in chaperone- and stress response protein-encoding genes, and protein levels of key BAG3 binding partners were perturbed. Molecular dynamics simulations of the BAG3-HSC70 complex predicted a partial disengagement by the R477H mutation. In line with this, BAG3-R477H bound less HSC70 than BAG3-WT in coimmunoprecipitation assays. Finally, myofibrillar disarray triggered by proteasome inhibition in R477H cells was mitigated by overexpression of the stress response protein heat shock factor 1 (HSF1). These studies reveal the importance of BAG3 in coordinating protein quality control subsystem usage within the cardiomyocyte and suggest that augmenting HSF1 activity might be beneficial as a means to mitigate proteostatic stress in the context of BAG3-associated DCM.
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http://dx.doi.org/10.1172/jci.insight.128799DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6948852PMC
November 2019

The ADP/ATP translocase drives mitophagy independent of nucleotide exchange.

Nature 2019 11 16;575(7782):375-379. Epub 2019 Oct 16.

Department of Medicine, Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.

Mitochondrial homeostasis depends on mitophagy, the programmed degradation of mitochondria. Only a few proteins are known to participate in mitophagy. Here we develop a multidimensional CRISPR-Cas9 genetic screen, using multiple mitophagy reporter systems and pro-mitophagy triggers, and identify numerous components of parkin-dependent mitophagy. Unexpectedly, we find that the adenine nucleotide translocator (ANT) complex is required for mitophagy in several cell types. Whereas pharmacological inhibition of ANT-mediated ADP/ATP exchange promotes mitophagy, genetic ablation of ANT paradoxically suppresses mitophagy. Notably, ANT promotes mitophagy independently of its nucleotide translocase catalytic activity. Instead, the ANT complex is required for inhibition of the presequence translocase TIM23, which leads to stabilization of PINK1, in response to bioenergetic collapse. ANT modulates TIM23 indirectly via interaction with TIM44, which regulates peptide import through TIM23. Mice that lack ANT1 show blunted mitophagy and consequent profound accumulation of aberrant mitochondria. Disease-causing human mutations in ANT1 abrogate binding to TIM44 and TIM23 and inhibit mitophagy. Together, our findings show that ANT is an essential and fundamental mediator of mitophagy in health and disease.
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http://dx.doi.org/10.1038/s41586-019-1667-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6858570PMC
November 2019

Myeloid Folliculin balances mTOR activation to maintain innate immunity homeostasis.

JCI Insight 2019 03 7;5. Epub 2019 Mar 7.

Department of Medicine, Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.

The mTOR pathway is central to most cells. How mTOR is activated in macrophages and modulates macrophage physiology remain poorly understood. The tumor suppressor Folliculin (FLCN) is a GAP for RagC/D, a regulator of mTOR. We show here that LPS potently suppresses FLCN in macrophages, allowing nuclear translocation of the transcription factor TFE3, leading to lysosome biogenesis, cytokine production, and hypersensitivity to inflammatory signals. Nuclear TFE3 additionally activates a transcriptional RagD positive feedback loop that stimulates FLCN-independent canonical mTOR signaling to S6K and increases cellular proliferation. LPS thus simultaneously suppresses the TFE3 arm and activates the S6K arm of mTOR. In vivo, mice lacking myeloid FLCN reveal chronic macrophage activation, leading to profound histiocytic infiltration and tissue disruption, with hallmarks of human histiocytic syndromes like Erdheim-Chester Disease. Our data thus identify a critical FLCN-mTOR-TFE3 axis in myeloid cells, modulated by LPS, that balances mTOR activation and curbs innate immune responses.
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http://dx.doi.org/10.1172/jci.insight.126939DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6483010PMC
March 2019

Loss of microRNA-23-27-24 clusters in skeletal muscle is not influential in skeletal muscle development and exercise-induced muscle adaptation.

Sci Rep 2019 01 31;9(1):1092. Epub 2019 Jan 31.

Division of Regenerative Medical Engineering, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan.

MicroRNAs are small regulatory noncoding RNAs that repress gene expression at the posttranscriptional level. Previous studies have reported that the expression of miR-23, miR-27, and miR-24, driven from two miR-23-27-24 clusters, is altered by various pathophysiological conditions. However, their functions in skeletal muscle have not been clarified. To define the roles of the miR-23-27-24 clusters in skeletal muscle, we generated double-knockout (dKO) mice muscle-specifically lacking the miR-23-27-24 clusters. The dKO mice were viable and showed normal growth. The contractile and metabolic features of the muscles, represented by the expression of the myosin heavy chain and the oxidative markers PGC1-α and COX IV, were not altered in the dKO mice compared with wild-type mice. The dKO mice showed increased cross-sectional areas of the oxidative fibers. However, this dKO did not induce functional changes in the muscles. The dKO mice also showed normal adaptation to voluntary wheel running for 4 weeks, including the glycolytic-to-oxidative fiber type switch, and increases in mitochondrial markers, succinate dehydrogenase activity, and angiogenesis. In conclusion, our data demonstrate that the miR-23-27-24 clusters have subtle effects on skeletal muscle development and endurance-exercise-induced muscle adaptation.
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http://dx.doi.org/10.1038/s41598-018-37765-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6355808PMC
January 2019

Role of endothelial microRNA-23 clusters in angiogenesis in vivo.

Am J Physiol Heart Circ Physiol 2018 10 15;315(4):H838-H846. Epub 2018 Jun 15.

Division of Regenerative Medical Engineering, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo , Tokyo , Japan.

The capillary network is distributed throughout the body, and its reconstruction is induced under various pathophysiological conditions. MicroRNAs are small noncoding RNAs that regulate gene expression via posttranscriptional mechanisms and are involved in many biological functions, including angiogenesis. Previous studies have shown that each microRNA of miR-23 clusters, composed of the miR-23a cluster (miR-23a~27a~24-2) and miR-23b cluster (miR-23b~27b~24-1), regulates angiogenesis in vitro. However, the role of miR-23 clusters, located within a single transcription unit, in angiogenesis in vivo has not been elucidated. In the present study, we generated vascular endothelial cell (EC)-specific miR-23 cluster double-knockout (DKO) mice and demonstrated sprouting angiogenesis under various conditions, including voluntary running exercise, hindlimb ischemia, skin wound healing, and EC sprouting from aorta explants. Here, we demonstrated that EC-specific miR-23 DKO mice are viable and fertile, with no gross abnormalities observed in pups or adults. The capillary number was normally increased in the muscles of these DKO mice in response to 2 wk of voluntary running and hindlimb ischemia. Furthermore, we did not observe any abnormalities in skin wound closure or EC sprouting from aortic ring explants in EC-specific miR-23 cluster DKO mice. Our results suggest that endothelial miR-23 clusters are dispensable for embryonic development and postnatal angiogenesis in vivo. NEW & NOTEWORTHY We generated vascular endothelial cell (EC)-specific miR-23a/b cluster double-knockout mice and determined sprouting angiogenesis under various conditions, including voluntary running exercise, hindlimb ischemia, skin wound healing, and EC sprouting from aorta explants. We demonstrated that the double-knockout mice were viable and fertile, with no gross abnormalities in exercise- and ischemia-induced angiogenesis and skin wound closure or EC sprouting from aortic ring explants.
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http://dx.doi.org/10.1152/ajpheart.00742.2017DOI Listing
October 2018

PDK4 Inhibits Cardiac Pyruvate Oxidation in Late Pregnancy.

Circ Res 2017 Dec 19;121(12):1370-1378. Epub 2017 Sep 19.

From the Cardiovascular Institute, Beth Israel Deaconess Medical Center, Boston, MA (L.X.L., F.D.); Corrigan Minehan Heart Center, Massachusetts General Hospital, Boston (L.X.L., F.D., M.C.C., S.D., A.R.); Division of Cardiovascular Disease, University of Alabama at Birmingham (G.C.R.); Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia (S.Y., J.L., S.W., M.M., Z.A.); Lewis-Sigler Institute for Integrative Genomics, Princeton University, NJ (W.L., C.J., J.D.R.); and Institute of Physiology I, Life and Brain Center, Medical Faculty, University of Bonn, Germany (M.H., B.K.F.).

Rationale: Pregnancy profoundly alters maternal physiology. The heart hypertrophies during pregnancy, but its metabolic adaptations, are not well understood.

Objective: To determine the mechanisms underlying cardiac substrate use during pregnancy.

Methods And Results: We use here C glucose, C lactate, and C fatty acid tracing analyses to show that hearts in late pregnant mice increase fatty acid uptake and oxidation into the tricarboxylic acid cycle, while reducing glucose and lactate oxidation. Mitochondrial quantity, morphology, and function do not seem altered. Insulin signaling seems intact, and the abundance and localization of the major fatty acid and glucose transporters, CD36 (cluster of differentiation 36) and GLUT4 (glucose transporter type 4), are also unchanged. Rather, we find that the pregnancy hormone progesterone induces PDK4 (pyruvate dehydrogenase kinase 4) in cardiomyocytes and that elevated PDK4 levels in late pregnancy lead to inhibition of PDH (pyruvate dehydrogenase) and pyruvate flux into the tricarboxylic acid cycle. Blocking PDK4 reverses the metabolic changes seen in hearts in late pregnancy.

Conclusions: Taken together, these data indicate that the hormonal environment of late pregnancy promotes metabolic remodeling in the heart at the level of PDH, rather than at the level of insulin signaling.
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http://dx.doi.org/10.1161/CIRCRESAHA.117.311456DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5722682PMC
December 2017

Adipose tissue browning: mTOR branches out.

Cell Cycle 2017 03 31;16(6):493-494. Epub 2017 Jan 31.

a Department of Medicine and Cardiovascular Institute , Perelman School of Medicine, University of Pennsylvania , Philadelphia , PA , USA.

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http://dx.doi.org/10.1080/15384101.2017.1285634DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5384586PMC
March 2017

The tumor suppressor FLCN mediates an alternate mTOR pathway to regulate browning of adipose tissue.

Genes Dev 2016 11 2;30(22):2551-2564. Epub 2016 Dec 2.

Department of Medicine and Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.

Noncanonical mechanistic target of rapamycin (mTOR) pathways remain poorly understood. Mutations in the tumor suppressor folliculin (FLCN) cause Birt-Hogg-Dubé syndrome, a hamartomatous disease marked by mitochondria-rich kidney tumors. FLCN functionally interacts with mTOR and is expressed in most tissues, but its role in fat has not been explored. We show here that FLCN regulates adipose tissue browning via mTOR and the transcription factor TFE3. Adipose-specific deletion of FLCN relieves mTOR-dependent cytoplasmic retention of TFE3, leading to direct induction of the PGC-1 transcriptional coactivators, drivers of mitochondrial biogenesis and the browning program. Cytoplasmic retention of TFE3 by mTOR is sensitive to ambient amino acids, is independent of growth factor and tuberous sclerosis complex (TSC) signaling, is driven by RagC/D, and is separable from canonical mTOR signaling to S6K. Codeletion of TFE3 in adipose-specific FLCN knockout animals rescues adipose tissue browning, as does codeletion of PGC-1β. Conversely, inducible expression of PGC-1β in white adipose tissue is sufficient to induce beige fat gene expression in vivo. These data thus unveil a novel FLCN-mTOR-TFE3-PGC-1β pathway-separate from the canonical TSC-mTOR-S6K pathway-that regulates browning of adipose tissue.
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http://dx.doi.org/10.1101/gad.287953.116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5159669PMC
November 2016

A branched-chain amino acid metabolite drives vascular fatty acid transport and causes insulin resistance.

Nat Med 2016 Apr 7;22(4):421-6. Epub 2016 Mar 7.

Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.

Epidemiological and experimental data implicate branched-chain amino acids (BCAAs) in the development of insulin resistance, but the mechanisms that underlie this link remain unclear. Insulin resistance in skeletal muscle stems from the excess accumulation of lipid species, a process that requires blood-borne lipids to initially traverse the blood vessel wall. How this trans-endothelial transport occurs and how it is regulated are not well understood. Here we leveraged PPARGC1a (also known as PGC-1α; encoded by Ppargc1a), a transcriptional coactivator that regulates broad programs of fatty acid consumption, to identify 3-hydroxyisobutyrate (3-HIB), a catabolic intermediate of the BCAA valine, as a new paracrine regulator of trans-endothelial fatty acid transport. We found that 3-HIB is secreted from muscle cells, activates endothelial fatty acid transport, stimulates muscle fatty acid uptake in vivo and promotes lipid accumulation in muscle, leading to insulin resistance in mice. Conversely, inhibiting the synthesis of 3-HIB in muscle cells blocks the ability of PGC-1α to promote endothelial fatty acid uptake. 3-HIB levels are elevated in muscle from db/db mice with diabetes and from human subjects with diabetes, as compared to those without diabetes. These data unveil a mechanism in which the metabolite 3-HIB, by regulating the trans-endothelial flux of fatty acids, links the regulation of fatty acid flux to BCAA catabolism, providing a mechanistic explanation for how increased BCAA catabolic flux can cause diabetes.
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http://dx.doi.org/10.1038/nm.4057DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4949205PMC
April 2016

MicroRNA-23a has minimal effect on endurance exercise-induced adaptation of mouse skeletal muscle.

Pflugers Arch 2015 Feb 23;467(2):389-98. Epub 2014 Apr 23.

Division of Regenerative Medical Engineering, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan.

Skeletal muscles contain several subtypes of myofibers that differ in contractile and metabolic properties. Transcriptional control of fiber-type specification and adaptation has been intensively investigated over the past several decades. Recently, microRNA (miRNA)-mediated posttranscriptional gene regulation has attracted increasing attention. MiR-23a targets key molecules regulating contractile and metabolic properties of skeletal muscle, such as myosin heavy-chains and peroxisome proliferator-activated receptor gamma, coactivator 1 alpha (PGC-1α). In the present study, we analyzed the skeletal muscle phenotype of miR-23a transgenic (miR-23a Tg) mice to explore whether forced expression of miR-23a affects markers of mitochondrial content, muscle fiber composition, and muscle adaptations induced by 4 weeks of voluntary wheel running. When compared with wild-type mice, protein markers of mitochondrial content, including PGC-1α, and cytochrome c oxidase complex IV (COX IV), were significantly decreased in the slow soleus muscle, but not the fast plantaris muscle of miR-23a Tg mice. There was a decrease in type IId/x fibers only in the soleus muscle of the Tg mice. Following 4 weeks of voluntary wheel running, there was no difference in the endurance exercise capacity as well as in several muscle adaptive responses including an increase in muscle mass, capillary density, or the protein content of myosin heavy-chain IIa, PGC-1α, COX IV, and cytochrome c. These results show that miR-23a targets PGC-1α and regulates basal metabolic properties of slow but not fast twitch muscles. Elevated levels of miR-23a did not impact on whole body endurance capacity or exercise-induced muscle adaptations in the fast plantaris muscle.
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http://dx.doi.org/10.1007/s00424-014-1517-zDOI Listing
February 2015

Profiling of circulating microRNAs after a bout of acute resistance exercise in humans.

PLoS One 2013 29;8(7):e70823. Epub 2013 Jul 29.

Faculty of Sport Sciences, Waseda University, Cooperative Major in Advanced Health Science, Tokyo University of Agriculture and Technology/Waseda University, Tokorozawa, Saitama, Japan.

Recent studies have revealed a new aspect of physiological regulation in which microRNAs (miRNAs) play fundamental roles in diverse biological and pathological processes. Furthermore, it was recently discovered that miRNAs are stably secreted into blood and that circulating miRNAs may play important roles in cell-cell communication. Here, we examined whether the circulating miRNA profile is affected by acute resistance exercise. Twelve males performed a resistance exercise session (bench press and leg press), consisting of five sets of 10 repetitions at 70% of maximum strength, with a 1 min rest between sets. Blood samples were taken before exercise, and at 0 and 60 min, 1 day, and 3 days after exercise. The circulating miRNA profile was determined by microarray analysis. Quantitative real-time PCR confirmed that the miR-149* level increased three days after resistance exercise. In contrast, the miR-146a and miR-221 levels decreased three days after resistance exercise. Our findings suggest that circulating miRNA levels change in response to acute resistance exercise, and miRNAs may play important roles in resistance-exercise-induced adaptation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0070823PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3726615PMC
August 2014

Regulation of miRNAs in human skeletal muscle following acute endurance exercise and short-term endurance training.

J Physiol 2013 Sep 24;591(18):4637-53. Epub 2013 Jun 24.

A. P. Russell: Centre for Physical Activity and Nutrition Research (C-PAN), School of Exercise and Nutrition Sciences, Deakin University, 221 Burwood Highway 3125, Burwood, Australia.

  The identification of microRNAs (miRNAs) has established new mechanisms that control skeletal muscle adaptation to exercise. The present study investigated the mRNA regulation of components of the miRNA biogenesis pathway (Drosha, Dicer and Exportin-5), muscle enriched miRNAs, (miR-1, -133a, -133b and -206), and several miRNAs dysregulated in muscle myopathies (miR-9, -23, -29, -31 and -181). Measurements were made in muscle biopsies from nine healthy untrained males at rest, 3 h following an acute bout of moderate-intensity endurance cycling and following 10 days of endurance training. Bioinformatics analysis was used to predict potential miRNA targets. In the 3 h period following the acute exercise bout, Drosha, Dicer and Exportin-5, as well as miR-1, -133a, -133-b and -181a were all increased. In contrast miR-9, -23a, -23b and -31 were decreased. Short-term training increased miR-1 and -29b, while miR-31 remained decreased. Negative correlations were observed between miR-9 and HDAC4 protein (r=-0.71; P=0.04), miR-31 and HDAC4 protein (r=-0.87; P=0.026) and miR-31 and NRF1 protein (r=-0.77; P=0.01) 3 h following exercise. miR-31 binding to the HDAC4 and NRF1 3 untranslated region (UTR) reduced luciferase reporter activity. Exercise rapidly and transiently regulates several miRNA species in muscle. Several of these miRNAs may be involved in the regulation of skeletal muscle regeneration, gene transcription and mitochondrial biogenesis. Identifying endurance exercise-mediated stress signals regulating skeletal muscle miRNAs, as well as validating their targets and regulatory pathways post exercise, will advance our understanding of their potential role/s in human health.
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http://dx.doi.org/10.1113/jphysiol.2013.255695DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3784204PMC
September 2013

Skeletal muscle adaptation in response to mechanical stress in p130cas-/- mice.

Am J Physiol Cell Physiol 2013 Mar 16;304(6):C541-7. Epub 2013 Jan 16.

Division of Regenerative Medical Engineering, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan.

Mammalian skeletal muscles undergo adaptation in response to changes in the functional demands upon them, involving mechanical-stress-induced cellular signaling called "mechanotransduction." We hypothesized that p130Cas, which is reported to act as a mechanosensor that transduces mechanical extension into cellular signaling, plays an important role in maintaining and promoting skeletal muscle adaptation in response to mechanical stress via the p38 MAPK signaling pathway. We demonstrate that muscle-specific p130Cas-/- mice express the contractile proteins normally in skeletal muscle. Furthermore, muscle-specific p130Cas-/- mice show normal mechanical-stress-induced muscle adaptation, including exercise-induced IIb-to-IIa muscle fiber type transformation and hypertrophy. Finally, we provide evidence that exercise-induced p38 MAPK signaling is not impaired by the muscle-specific deletion of p130Cas. We conclude that p130Cas plays a limited role in mechanical-stress-induced skeletal muscle adaptation.
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http://dx.doi.org/10.1152/ajpcell.00243.2012DOI Listing
March 2013

Disruption of skeletal muscle mitochondrial network genes and miRNAs in amyotrophic lateral sclerosis.

Neurobiol Dis 2013 Jan 4;49:107-17. Epub 2012 Sep 4.

Division of Regenerative Medical Engineering, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Bunkyo, 113-0033 Tokyo, Japan. Electronic address:

Skeletal muscle mitochondrial dysfunction is believed to play a role in the progression and severity of amyotrophic lateral sclerosis (ALS). The regulation of transcriptional co-activators involved in mitochondrial biogenesis and function in ALS is not well known. When compared with healthy control subjects, patients with ALS, but not neurogenic disease (ND), had lower levels of skeletal muscle peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) mRNA and protein and estrogen-related receptor-α (ERRα) and mitofusin-2 (Mfn2) mRNA. PGC-1β, nuclear respiratory factor-1 (NRF-1) and Mfn1 mRNA as well as cytochrome C oxidase subunit IV (COXIV) mRNA and protein were lower in patients with ALS and ND. Both patient groups had reductions in citrate synthase and cytochrome c oxidase activity. Similar observations were made in skeletal muscle from transgenic ALS G93A transgenic mice. In vitro, PGC-1α and PGC-1β regulated Mfn1 and Mfn2 in an ERRα-dependent manner. Compared to healthy controls, miRNA 23a, 29b, 206 and 455 were increased in skeletal muscle of ALS patients. miR-23a repressed PGC-1α translation in a 3' UTR dependent manner. Transgenic mice over expressing miR-23a had a reduction in PGC-1α, cytochome-b and COXIV protein levels. These results show that skeletal muscle mitochondrial dysfunction in ALS patients is associated with a reduction in PGC-1α signalling networks involved in mitochondrial biogenesis and function, as well as increases in several miRNAs potentially implicated in skeletal muscle and neuromuscular junction regeneration. As miR-23a negatively regulates PGC-1α signalling, therapeutic inhibition of miR-23a may be a strategy to rescue PGC-1α activity and ameliorate skeletal muscle mitochondrial function in ALS.
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http://dx.doi.org/10.1016/j.nbd.2012.08.015DOI Listing
January 2013

Translational suppression of atrophic regulators by microRNA-23a integrates resistance to skeletal muscle atrophy.

J Biol Chem 2011 Nov 18;286(44):38456-38465. Epub 2011 Sep 18.

Division of Regenerative Medical Engineering, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan; Institute for Biomedical Engineering Consolidated Research Institute for Advanced Science and Medical Care, Waseda University, Shinjuku, Tokyo 162-0041, Japan; Venetian Institute of Molecular Medicine, 35129 Padova, Italy. Electronic address:

Muscle atrophy is caused by accelerated protein degradation and occurs in many pathological states. Two muscle-specific ubiquitin ligases, MAFbx/atrogin-1 and muscle RING-finger 1 (MuRF1), are prominently induced during muscle atrophy and mediate atrophy-associated protein degradation. Blocking the expression of these two ubiquitin ligases provides protection against muscle atrophy. Here we report that miR-23a suppresses the translation of both MAFbx/atrogin-1 and MuRF1 in a 3'-UTR-dependent manner. Ectopic expression of miR-23a is sufficient to protect muscles from atrophy in vitro and in vivo. Furthermore, miR-23a transgenic mice showed resistance against glucocorticoid-induced skeletal muscle atrophy. These data suggest that suppression of multiple regulators by a single miRNA can have significant consequences in adult tissues.
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http://dx.doi.org/10.1074/jbc.M111.271270DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3207415PMC
November 2011