Genomic and Proteomic Profiling Reveals Reduced Mitochondrial Function and Disruption of the Neuromuscular Junction Driving Rat Sarcopenia

Ibebunjo, Chikwendu; Chick, Joel M.; Kendall, Tracee L.; Eash, John K.; Li, Christine; Zhang, Yunyu; Vickers, Chad; Wu, Zhidan; Clarke, Brian; Shi, Jun; Cruz, Joseph; Fournier, Brigitte; Brachat, Sophie; Gutzwiller, Sabine; Ma, Qicheng; Markovits, Judith; Broome, Michelle; Steinkrauss, Michelle; Skuba, Elizabeth; Galarneau, Jean-René; Gygi, Steven P.; Glass, David J.

doi:10.1128/mcb.01036-12

Cited by 239 publications

(280 citation statements)

References 79 publications

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“…This alteration in gene expression was met with a parallel progressive reduction in DNA methylation with significance being observed at both 7 and 14 d after TTXinduced atrophy. An observation similar to previous work (54), in which a significant increase in Chrna1 activity was observed as a result of sarcopenia. nAChRs are made up of 5 isoforms in human skeletal muscle, in which the subunit Chrna1 is most dominant.…”

Section: Discussion Summarysupporting

confidence: 92%

Transcriptomic and epigenetic regulation of disuse atrophy and the return to activity in skeletal muscle

et al. 2017

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Physical inactivity and disuse are major contributors to age-related muscle loss. Denervation of skeletal muscle has been previously used as a model with which to investigate muscle atrophy following disuse. Although gene regulatory networks that control skeletal muscle atrophy after denervation have been established, the transcriptome in response to the recovery of muscle after disuse and the associated epigenetic mechanisms that may function to modulate gene expression during skeletal muscle atrophy or recovery have yet to be investigated. We report that silencing the tibialis anterior muscle in rats with tetrodotoxin (TTX)-administered to the common peroneal nerve-resulted in reductions in muscle mass of 7, 29, and 51% with corresponding reductions in muscle fiber cross-sectional area of 18, 42, and 69% after 3, 7, and 14 d of TTX, respectively. Of importance, 7 d of recovery, during which rodents resumed habitual physical activity, restored muscle mass from a reduction of 51% after 14 d TTX to a reduction of only 24% compared with sham control. Returning muscle mass to levels observed at 7 d TTX administration (29% reduction). Transcriptome-wide analysis demonstrated that 3714 genes were differentially expressed across all conditions at a significance of P £ 0.001 after disuse-induced atrophy. Of interest, after 7 d of recovery, the expression of genes that were most changed during TTX had returned to that of the sham control. The 20 most differentially expressed genes after microarray analysis were identified across all conditions and were cross-referenced with the most frequently occurring differentially expressed genes between conditions. This gene subset included myogenin (MyoG), Hdac4, Ampd3, Trim63 (MuRF1), and acetylcholine receptor subunit a1 (Chrna1). Transcript expression of these genes and Fboxo32 (MAFbx), because of its previously identified role in disuse atrophy together with Trim63 (MuRF1), were confirmed by real-time quantitative RT-PCR, and DNA methylation of their promoter regions was analyzed by PCR and pyrosequencing. MyoG, Trim63 (MuRF1), Fbxo32 (MAFbx), and Chrna1 demonstrated significantly decreased DNA methylation at key time points after disuseinduced atrophy that corresponded with significantly increased gene expression. Of importance, after TTX cessation and 7 d of recovery, there was a marked increase in the DNA methylation profiles of Trim63 (MuRF1) and Chrna1 back to control levels. This also corresponded with the return of gene expression in the recovery group back to baseline expression observed in sham-operated controls. To our knowledge, this is the first study to demonstrate that skeletal muscle atrophy in response to disuse is accompanied by dynamic epigenetic modifications that are associated with alterations in gene expression, and that these epigenetic modifications and gene expression profiles are reversible after skeletal muscle returns to normal

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Section: Discussion Summarysupporting

confidence: 92%

Transcriptomic and epigenetic regulation of disuse atrophy and the return to activity in skeletal muscle

et al. 2017

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“…Age‐associated changes occur not only in muscle and nerve, but also at the interface between the two, the NMJ. Age‐related morphologic NMJ changes have been previously described (Balice‐Gordon, 1997; Boaro et al., 1998; Chai, Vukovic, Dunlop, Grounds & Shavlakadze, 2011; Deschenes et al., 2010; Jang & Van Remmen, 2010; Kawabuchi et al., 2001; Luff, 1998; McMullen & Andrade, 2009; Smith & Chapman, 1987; Steinbach, 1981; Wernig & Herrera, 1986), and NMJ disruption has been identified as a driver of sarcopenia in a rodent model (Ibebunjo et al., 2013). The majority of those studies, however, described changes in nerve terminals or AChRs.…”

Section: Discussionmentioning

confidence: 99%

Hypothalamic Sirt1 protects terminal Schwann cells and neuromuscular junctions from age‐related morphological changes

et al. 2018

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SummaryNeuromuscular decline occurs with aging. The neuromuscular junction (NMJ), the interface between motor nerve and muscle, also undergoes age‐related changes. Aging effects on the NMJ components—motor nerve terminal, acetylcholine receptors (AChRs), and nonmyelinating terminal Schwann cells (tSCs)—have not been comprehensively evaluated. Sirtuins delay mammalian aging and increase longevity. Increased hypothalamic Sirt1 expression results in more youthful physiology, but the relationship between NMJ morphology and hypothalamic Sirt1 was previously unknown. In wild‐type mice, all NMJ components showed age‐associated morphological changes with ~80% of NMJs displaying abnormalities by 17 months of age. Aged mice with brain‐specific Sirt1 overexpression (BRASTO) had more youthful NMJ morphologic features compared to controls with increased tSC numbers, increased NMJ innervation, and increased numbers of normal AChRs. Sympathetic NMJ innervation was increased in BRASTO mice. In contrast, hypothalamic‐specific Sirt1 knockdown led to tSC abnormalities, decreased tSC numbers, and more denervated endplates compared to controls. Our data suggest that hypothalamic Sirt1 functions to protect NMJs in skeletal muscle from age‐related changes via sympathetic innervation.

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“…These individual proteins varied over multiple orders of magnitude. In the present study, and in agreement with other aging studies in rodents (Alves et al., 2010; Hwang et al., 2014; Ibebunjo et al., 2012; Ori et al., 2015; Walther & Mann, 2011) and humans (Short et al., 2005), we show relatively small changes in protein concentrations between age groups, rarely exceeding a twofold change (Table S4). Conceivably, larger changes involved in stable tissue differentiation may be regulated primarily at the transcriptome level, while more subtle metabolic adaptations are regulated downstream.…”

Section: Discussionmentioning

confidence: 99%

“…mRNA abundances have been measured in biopsies from young and elderly people (Irving et al., 2015), with and without regular exercise regimes (Johnson, Lanza, Short, Asmann, & Nair, 2014). For aging rodents, multiple muscle proteome and transcriptome profiles are available, measured at different time points and subject to different interventions (Alves et al., 2010; Hwang et al., 2014; Ibebunjo et al., 2012; Padrao, Ferreira, Amado, Vitorino, & Duarte, 2016). These transcriptome and proteome data were, however, analysed separately from each other and from metabolic data.…”

Section: Introductionmentioning

confidence: 99%

Running‐wheel activity delays mitochondrial respiratory flux decline in aging mouse muscle via a post‐transcriptional mechanism

et al. 2017

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SummaryLoss of mitochondrial respiratory flux is a hallmark of skeletal muscle aging, contributing to a progressive decline of muscle strength. Endurance exercise alleviates the decrease in respiratory flux, both in humans and in rodents. Here, we dissect the underlying mechanism of mitochondrial flux decline by integrated analysis of the molecular network.Mice were given a lifelong ad libitum low‐fat or high‐fat sucrose diet and were further divided into sedentary and running‐wheel groups. At 6, 12, 18 and 24 months, muscle weight, triglyceride content and mitochondrial respiratory flux were analysed. Subsequently, transcriptome was measured by RNA‐Seq and proteome by targeted LC‐MS/MS analysis with 13C‐labelled standards. In the sedentary groups, mitochondrial respiratory flux declined with age. Voluntary running protected the mitochondrial respiratory flux until 18 months of age. Beyond this time point, all groups converged. Regulation Analysis of flux, proteome and transcriptome showed that the decline of flux was equally regulated at the proteomic and at the metabolic level, while regulation at the transcriptional level was marginal. Proteomic regulation was most prominent at the beginning and at the end of the pathway, namely at the pyruvate dehydrogenase complex and at the synthesis and transport of ATP. Further proteomic regulation was scattered across the entire pathway, revealing an effective multisite regulation. Finally, reactions regulated at the protein level were highly overlapping between the four experimental groups, suggesting a common, post‐transcriptional mechanism of muscle aging.

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Genomic and Proteomic Profiling Reveals Reduced Mitochondrial Function and Disruption of the Neuromuscular Junction Driving Rat Sarcopenia

Cited by 239 publications

References 79 publications

Transcriptomic and epigenetic regulation of disuse atrophy and the return to activity in skeletal muscle

Transcriptomic and epigenetic regulation of disuse atrophy and the return to activity in skeletal muscle

Hypothalamic Sirt1 protects terminal Schwann cells and neuromuscular junctions from age‐related morphological changes

Running‐wheel activity delays mitochondrial respiratory flux decline in aging mouse muscle via a post‐transcriptional mechanism

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