scholarly journals RESTORATION OF HYPOXIA SIGNALING IMPROVES AGING-ASSOCIATED LOSS OF SKELETAL MUSCLE REGENERATIVE POTENTIAL

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S730-S731
Author(s):  
Kodi Udeh ◽  
Bin Li ◽  
Yori Endo ◽  
Adriana Panayi ◽  
Dharaniya Sakthivel ◽  
...  
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Ex Vivo ◽  
Post Injury ◽  
Cross Sectional ◽  
Protein Levels ◽  
Aryl Hydrocarbon ◽  
Ability To Regenerate ◽  
Old Mice ◽  
Hypoxia Signaling

Abstract Skeletal muscle retains the ability to regenerate throughout life, but this decreases significantly with aging. The present study investigates whether aging-associated loss of muscle hypoxia signaling limits regenerative potential. Utilizing young (3 months) and old (22-24 months) mice, skeletal muscle from old mice exhibited a 40% decline in the cross-sectional area (CSA) of newly regenerating fibers following cryoinjury at day 10 (p < 0.01) post-injury as compared to young. Focused PCR array demonstrated a greater than 3-fold decline in expression of the majority of hypoxia signaling genes. In particular, aryl hydrocarbon receptor nuclear translocator (ARNT), which is required for downstream hypoxia signaling and the transcription of hypoxia response genes, is 5-fold lower for both gene expression (p < 0.01) and protein levels (p < 0.01) in old versus young mice. To determine the effects of ARNT on muscle regeneration, we utilized a genetically modified mouse which results in an 80% decrease in ARNT gene expression following activation, specifically in skeletal muscle. Compared to littermate controls, mice with a muscle specific knockdown of ARNT (mKO ARNT) exhibit a 30% decline in regenerating fiber sizes at day 10 (p < 0.01) following cryoinjury, without any loss of regenerative potential in FACS isolated satellite cells ex vivo. Administration of a pharmacologic hypoxia activator, ML228, induced a 30% increase in regenerating fiber CSA in both old mice and mKO ARNT mice (p < 0.01) as compared to treatment with vehicle control. These data suggest hypoxia signaling declines with aging in skeletal muscle and activation of hypoxia signaling may promote regeneration.

scholarly journals Serine and Glycine Are Essential for Skeletal Muscle Regeneration Following Injury

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 81-81
Author(s):  
Anna Thalacker-Mercer ◽  
Jamie Blum ◽  
Brandon Gheller
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Essential Amino Acids ◽  
Regenerative Process ◽  
Skeletal Muscle Regeneration ◽  
Post Injury ◽  
Foreign Study ◽  
Funding Sources ◽  
Age Related ◽  
Old Mice

Abstract Objectives Skeletal muscle (SkM) regeneration post injury is reliant on SkM-specific stem cells (muscle progenitor cells [MPCs]) and a well-orchestrated myogenic program. The regenerative process is impaired with advancing age, potentiating pathological SkM remodeling (infiltration of fat and fibrotic tissues). We have previously demonstrated that the nutritionally non-essential amino acids serine (Ser) and glycine (Gly) are required for early stages of SkM regeneration (MPC proliferation). However, Ser and Gly availability (SkM and circulating) declines with aging. The objective was to test the hypothesis that reduced endogenous Ser/Gly during regeneration promotes pathological SkM remodeling in aged animals. Methods Old mice (∼20 months of age) were given a Ser/Gly depleted diet (SGdep) or an isonitrogenous, isoenergetic diet containing Ser/Gly (SGcont) for 4 weeks followed by notexin-induced injury to the tibialis anterior (TA) SkM. At 28 days post injury the TA was harvested and histological analysis of SkM morphology (H&E and immunofluorescence [IF]) and gene expression analyses (qPCR) were completed. Results Old mice receiving the SGdep diet had a shift toward reduced myofiber size and enhanced adipocyte infiltration in the SkM. Adipocyte infiltration was confirmed with IF of perilipin-1, an adipocyte marker. Uninjured mice on the SGdep diet did not demonstrate altered SkM morphology. Gene expression analysis of differentially expressed genes underlying SkM remodeling (reduced myofiber size and increased fat infiltration) with SGdep is ongoing. Conclusions Reduced Ser and Gly availability following injury instigates SkM remodeling in old mice, which could explain in part age-related impairments in SkM regeneration. This research underscores the essentiality of Ser and Gly for the SkM regenerative process particularly with advancing age. Funding Sources Canadian Institutes of Health Research Doctoral Foreign Study Award to BG.

Aging does not alter the mechanosensitivity of the p38, p70S6k, and JNK2 signaling pathways in skeletal muscle

2005 ◽  
Vol 98 (4) ◽  
pp. 1562-1566 ◽  
Author(s):  
Troy A. Hornberger ◽  
R. D. Mateja ◽  
E. R. Chin ◽  
J. L. Andrews ◽  
K. A. Esser
Keyword(s):  
Skeletal Muscle ◽  
Signaling Pathways ◽  
Ex Vivo ◽  
Mechanical Stimuli ◽  
S6 Kinase ◽  
Diminished Capacity ◽  
Ribosomal S6 Kinase ◽  
Passive Stretch ◽  
Old Mice ◽  
Dependent Mechanism

The capacity for skeletal muscle to recover its mass following periods of unloading (regrowth) has been reported to decline with age. Although the mechanisms responsible for the impaired regrowth are not known, it has been suggested that aged muscles have a diminished capacity to sense and subsequently respond to a given amount of mechanical stimuli (mechanosensitivity). To test this hypothesis, extensor digitorum longus muscles from young (2–3 mo) and old (26–27 mo) mice were subjected to intermittent 15% passive stretch (ex vivo) as a source of mechanical stimulation and analyzed for alterations in the phosphorylation of stress-activated protein kinase (p38), ribosomal S6 kinase (p70S6k), and the p54 jun N-terminal kinase (JNK2). The results indicated that the average magnitude of specific tension (mechanical stimuli) induced by 15% stretch was similar in muscles from young and old mice. Young and old muscles also revealed similar increases in the magnitude of mechanically induced p38, p70S6k (threonine/serine 421/424 and threonine 389), and JNK2 phosphorylation. In addition, coincubation experiments demonstrated that the release of locally acting growth factors was not sufficient for the induction of JNK2 phosphorylation, suggesting that JNK2 was activated by a mechanical rather than a mechanical/growth factor-dependent mechanism. Taken together, the results of this study demonstrate that aging does not alter the mechanosensitivity of the p38, p70S6k, and JNK2 signaling pathways in skeletal muscle.

scholarly journals Physical exercise increases Sestrin 2 protein levels and induces autophagy in the skeletal muscle of old mice

2017 ◽  
Vol 97 ◽  
pp. 17-21 ◽  
Author(s):  
Luciene Lenhare ◽  
Barbara M. Crisol ◽  
Vagner R.R. Silva ◽  
Carlos K. Katashima ◽  
André V. Cordeiro ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Physical Exercise ◽  
Protein Levels ◽  
Old Mice

scholarly journals Association between vitamin D deficiency and exercise capacity in patients with CKD, a cross-sectional analysis

2020 ◽  
Author(s):  
Emma L Watson ◽  
Thomas J Wilkinson ◽  
Tom F O’Sullivan ◽  
Luke A Baker ◽  
Douglas W Gould ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Vitamin D ◽  
Vitamin D Deficiency ◽  
Exercise Capacity ◽  
Muscle Mass ◽  
Ex Vivo ◽  
Muscle Size ◽  
Cross Sectional ◽  
Cross Sectional Analysis ◽  
Sectional Analysis

AbstractEvidence is growing for a role of vitamin D in regulating skeletal muscle mass, strength and functional capacity. Given the role the kidneys play in activating total vitamin D, and the high prevalence of vitamin D deficiency in Chronic Kidney Disease (CKD), it is possible that deficiency contributes to the low levels of physical function and muscle mass in these patients. This is a secondary cross-sectional analysis of previously published interventional study, with ex vivo follow up work. 34 CKD patients at stages G3b-5 (eGFR 25.5 ± 8.3ml/min/1.73m2; age 61 ± 12 years) were recruited, with a sub-group (n=20) also donating a muscle biopsy. Vitamin D and associated metabolites were analysed in plasma by liquid chromatography tandem-mass spectroscopy and correlated to a range of physiological tests of muscle size, function, exercise capacity and body composition. The effects of 1α,25(OH)2D3 supplementation on myogenesis and myotube size was investigated in primary skeletal muscle cells from vitamin D deficient donors. In vivo, there was no association between total or active vitamin D and muscle size or strength, but a significant correlation with was seen with the total form. Ex vivo, 1α,25(OH)2D3 supplementation reduced IL-6 mRNA expression, but had no effect upon proliferation, differentiation or myotube diameter. This early preliminary work suggests that vitamin D deficiency is not a prominent factor driving the loss of muscle mass in CKD, but may play a role in reduced exercise capacity.

scholarly journals OR-009 The expression and roles of lncRNAs in the regeneration of skeletal muscle contusion

2018 ◽  
Vol 1 (2) ◽  
Author(s):  
Lifang Zheng ◽  
Peijie Chen ◽  
Weihua Xiao
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Muscle Regeneration ◽  
Myoblast Differentiation ◽  
Control Group ◽  
Myogenic Regulatory Factors ◽  
Post Injury ◽  
Regulatory Factors ◽  
Expression Levels ◽  
Skeletal Muscle Contusion

Objective In recent years, Accumulating evidence from myoblast differentiation in vitro, cardiotoxin (CTX)-mediated injury or mdx mice suggested that some lncRNAs such as Malat1, H19, linc-MD1, linc-YY1, Sirt1 AS and lnc-mg may modulate myogenesis and muscle regeneration. However, the change of lncRNAs in skeletal muscle contusion and their possible roles are still unclear. We hypothesize that the lncRNAs may be involved in the repair of skeletal muscle contusion. Methods Forty C57BL/6 male mice were randomly divided into two groups, uninjured control group (group C) and muscle contusion group (group S). The mice of group S suffered from contusion injury. All the mice were killed to harvest gastrocnemius at 3, 6, 12 and 24 days post-injury. The gene expression were detected by PCR technique. Gastrocnemius were stained with H & E to evaluate the general morphology. Data were analyzed by One-way analysis of variance, with statistical significance being set at p ≤ 0.05. Results The expression levels of linc-MD1 and Sirt1 AS were significantly higher than that of the uninjured control group at 3, 6 and 12 days post-injury (p<0.01). And Malat1 was highly expressed in the skeletal muscle of the muscle contusion group at 3 days post-injury and continuously up-regulated at 6 days (p<0.01). Moreover, linc-YY1 and H19 were all elevated significantly at 6 days (all p<0.01), but their gene expression levels did not change significantly at 3, 12 and 24 days post-injury, as compared to the uninjured control group. Furthermore, lnc-mg mRNA level did not change significantly in the whole process of regeneration after muscle contusion except the time point of 12 days post-injury which decreased significantly (p<0.01). The expression of myogenic regulatory factors (MyoD, myogenin, myf5, myf6) were studied, they were all elevated significantly at 3 and 6 days (all p<0.01; except myogenin ), and returned to normal at 24 days post-injury, as compared to the uninjured control group. Meanwhile, Pearson correlations showed that there was an correlation between lincRNAs and myogenic regulatory factors mentioned above. Conclusions The expression of myogenic regulatory factors increased significantly after muscle contusion. Meanwhile, varieties of lncRNAs (Malat1, H19, lnc-mg, linc-MD1, linc-YY1, Sirt1 AS) were also up-regulated. Moreover, there was correlation between lncRNAs and myogenic regulatory factors for skeletal muscle regeneration. These results suggest that lncRNAs may play important roles in the regeneration of skeletal muscle contusion.

scholarly journals Inactivation of the Euchromatic Histone-Lysine N-Methyltransferase 2 Pathway in Pancreatic Epithelial Cells Antagonizes Cancer Initiation and Pancreatitis-Associated Promotion by Altering Growth and Immune Gene Expression Networks

2021 ◽  
Vol 9 ◽  
Author(s):  
Guillermo Urrutia ◽  
Thiago Milech de Assuncao ◽  
Angela J. Mathison ◽  
Ann Salmonson ◽  
Romica Kerketta ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Networks ◽  
Ex Vivo ◽  
Mapk Pathway ◽  
Intraepithelial Neoplasia ◽  
Ductal Adenocarcinoma ◽  
Immune Gene ◽  
Protein Levels ◽  
Histone Lysine

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive, painful disease with a 5-year survival rate of only 9%. Recent evidence indicates that distinct epigenomic landscapes underlie PDAC progression, identifying the H3K9me pathway as important to its pathobiology. Here, we delineate the role of Euchromatic Histone-lysine N-Methyltransferase 2 (EHMT2), the enzyme that generates H3K9me, as a downstream effector of oncogenic KRAS during PDAC initiation and pancreatitis-associated promotion. EHMT2 inactivation in pancreatic cells reduces H3K9me2 and antagonizes KrasG12D-mediated acinar-to-ductal metaplasia (ADM) and Pancreatic Intraepithelial Neoplasia (PanIN) formation in both the Pdx1-Cre and P48Cre/+KrasG12D mouse models. Ex vivo acinar explants also show impaired EGFR-KRAS-MAPK pathway-mediated ADM upon EHMT2 deletion. Notably, KrasG12D increases EHMT2 protein levels and EHMT2-EHMT1-WIZ complex formation. Transcriptome analysis reveals that EHMT2 inactivation upregulates a cell cycle inhibitory gene expression network that converges on the Cdkn1a/p21-Chek2 pathway. Congruently, pancreas tissue from KrasG12D animals with EHMT2 inactivation have increased P21 protein levels and enhanced senescence. Furthermore, loss of EHMT2 reduces inflammatory cell infiltration typically induced during KrasG12D-mediated initiation. The inhibitory effect on KrasG12D-induced growth is maintained in the pancreatitis-accelerated model, while simultaneously modifying immunoregulatory gene networks that also contribute to carcinogenesis. This study outlines the existence of a novel KRAS-EHMT2 pathway that is critical for mediating the growth-promoting and immunoregulatory effects of this oncogene in vivo, extending human observations to support a pathophysiological role for the H3K9me pathway in PDAC.

scholarly journals Involvement of the Extracellular Matrix Proteins Periostin and Tenascin C in Nasal Polyp Remodeling by Regulating the Expression of MMPs

2020 ◽  
Author(s):  
Kun Du ◽  
Min Wang ◽  
Nan Zhang ◽  
Ping Wang ◽  
Pei Yu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Epithelial Cells ◽  
Chronic Rhinosinusitis ◽  
Nasal Polyp ◽  
Nasal Polyps ◽  
Ex Vivo ◽  
Tissue Remodeling ◽  
Tenascin C ◽  
Protein Levels ◽  
Control Subjects

Abstract Background: Tissue remodeling caused by increased MMPs is involved in the pathogenesis of chronic rhinosinusitis with nasal polyposis (CRSwNP). We previously found higher levels of periostin and tenascin C in CRSwNPs, but whether they are associated with the dysregulation of MMPs is unknown. Therefore, the present study aimed to investigate the regulatory roles of two ECM proteins in the expression of MMPs in nasal polyps.Methods：The concentrations of MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-12, MMP-13, TIMP-1, TIMP-2, TIMP-3, TIMP-4, periostin, and tenascin C in tissue homogenates of 51 patients with chronic rhinosinusitis with and without nasal polyps and 15 control subjects were measured and their correlations were analyzed. Primary human nasal polyp fibroblasts and epithelial cells were stimulated ex vivo with periostin and tenascin C and the gene expression of MMPs and TIMPs was determined by means of real-time PCR.Results: The protein levels of MMP-3, MMP-7, MMP-8, MMP-9, TIMP-1, TIMP-2, periostin, and tenascin C were significantly higher in patients with CRSwNPs than in healthy control subjects. Periostin was positively correlated with MMP-3 and TIMP-2, and tenascin C was positively correlated with MMP-3, MMP-7, MMP-8, MMP-9 and TIMP-2. Periostin stimulated the gene expression of MMP-3, MMP-7, and MMP-9 in fibroblasts and MMP-7 in epithelial cells ex vivo. Tenascin C stimulated the expression of MMP-3, MMP-8, and MMP-9 in epithelial cells, but not in fibroblasts. The expression of TIMPs in fibroblasts and epithelial cells was affected by neither periostin nor tenascin C. Conclusions：Periostin and tenascin C might be involved in the remodeling of nasal polyps by regulating the expression of different MMPs in epithelial cells and fibroblasts. Our findings have the potential to identify key factors of tissue remodeling in CRSwNPs.

scholarly journals Hyperthermia increases interleukin-6 in mouse skeletal muscle

2012 ◽  
Vol 303 (4) ◽  
pp. C455-C466 ◽  
Author(s):  
Steven S. Welc ◽  
Neil A. Phillips ◽  
Jose Oca-Cossio ◽  
Shannon M. Wallet ◽  
Daniel L. Chen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Core Temperature ◽  
Ex Vivo ◽  
C2c12 Myotubes ◽  
Tnf Α ◽  
Passive Hyperthermia ◽  
Circulating Levels ◽  
Cell Supernatant

Skeletal muscles produce and contribute to circulating levels of IL-6 during exercise. However, when core temperature is reduced, the response is attenuated. Therefore, we hypothesized that hyperthermia may be an important and independent stimulus for muscle IL-6. In cultured C2C12 myotubes, hyperthermia (42°C) increased IL-6 gene expression 14-fold after 1 h and 35-fold after 5 h of 37°C recovery; whereas exposure to 41°C resulted in a 2.6-fold elevation at 1 h. IL-6 protein was secreted and significantly elevated in the cell supernatant. Similar but reduced responses to heat were seen in C2C12 myoblasts. Isolated soleus muscles from mice, exposed ex vivo to 41°C for 1 h, yielded similar IL-6 gene responses (>3-fold) but without a significant effect on protein release. When whole animals were exposed to passive hyperthermia, such that core temperature increased to 42.4°C, IL-6 mRNA in soleus increased 5.4-fold compared with time matched controls. Interestingly, TNF-α gene expression was routinely suppressed at all levels of hyperthermia (40.5–42°C) in the isolated models, but TNF-α was elevated (4.2-fold) in the soleus taken from intact mice exposed, in vivo, to hyperthermia. Muscle HSP72 mRNA increased as a function of the level of hyperthermia, and IL-6 mRNA responses increased proportionally with HSP72. In cultured C2C12 myotubes, when heat shock factor was pharmacologically blocked with KNK437, both HSP72 and IL-6 mRNA elevations, induced by heat, were suppressed. These findings implicate skeletal muscle as a “heat stress sensor” at physiologically relevant hyperthermia, responding with a programmed cytokine expression pattern characterized by elevated IL-6.

scholarly journals Nutritional regulation of renal lipogenic factor expression in mice: comparison to regulation in the liver and skeletal muscle

2017 ◽  
Vol 313 (4) ◽  
pp. F887-F898 ◽  
Author(s):  
Suk-Jeong Kim ◽  
Ji-Eun Kim ◽  
Yong-Woon Kim ◽  
Jong-Yeon Kim ◽  
So-Young Park
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Nutritional Regulation ◽  
Obese Mice ◽  
Lipogenic Gene ◽  
Protein Levels ◽  
Lipogenic Gene Expression ◽  
Element Binding Protein ◽  
Fasting And Refeeding ◽  
Renal Expression

Regulation of lipogenesis by pathophysiological factors in the liver and skeletal muscle is well understood; however, regulation in the kidney is still unclear. To elucidate nutritional regulation of lipogenic factors in the kidney, we measured the renal expression of lipogenic transcriptional factors and enzymes during fasting and refeeding in chow-fed and high-fat-fed mice. We also examined the regulatory effect of the liver X receptor (LXR) on the expression of lipogenic factors. The renal gene expression of sterol regulatory element-binding protein (SREBP)-1c and fatty acid synthase (FAS) was reduced by fasting for 48 h and restored by refeeding, whereas the mRNA levels of forkhead box O (FOXO)1/3 were increased by fasting and restored by refeeding. Accordingly, protein levels of SREBP-1, FAS, and phosphorylated FOXO1/3 were reduced by fasting and restored by refeeding. The patterns of lipogenic factors expression in the kidney were similar to those in the liver and skeletal muscle. However, this phasic regulation of renal lipogenic gene expression was blunted in diet-induced obese mice. LXR agonist TO901317 increased the lipogenic gene expression and the protein levels of SREBP-1 precursor and FAS but not nuclear SREBP-1. Moreover, increases in insulin-induced gene mRNA and nuclear carbohydrate-responsive element binding protein (ChREBP) levels were observed in the TO901317-treated mice. These results suggest that the kidney shows flexible suppression and restoration of lipogenic factors following fasting and refeeding in lean mice, but this is blunted in obese mice. LXR is involved in the renal expression of lipogenic enzymes, and ChREBP may mediate the response.

scholarly journals Impact of a single session of intermittent pneumatic leg compressions on skeletal muscle and isolated artery gene expression in rats

2011 ◽  
Vol 301 (6) ◽  
pp. R1658-R1668 ◽  
Author(s):  
Bruno T. Roseguini ◽  
Arturo A. Arce-Esquivel ◽  
Sean C. Newcomer ◽  
M. H. Laughlin
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Vascular Remodeling ◽  
Single Session ◽  
Monocyte Chemoattractant Protein 1 ◽  
Protein Levels ◽  
Perforating Artery ◽  
Collateral Arteries ◽  
Clinical Benefits ◽  
A Minor

Intermittent pneumatic leg compressions (IPC) have proven to be an effective noninvasive approach for treatment of patients with claudication, but the mechanisms underlying the clinical benefits remain elusive. In the present study, a rodent model of claudication produced by bilateral ligation of the femoral artery was used to investigate the acute impact of a single session of IPC (150 min) on hemodynamics, skeletal muscle (tibialis anterior), and isolated collateral artery (perforating artery) expression of a subset of genes associated with inflammation and vascular remodeling. In addition, the effect of compression frequency (15 vs. 3 compressions/min) on the expression of these factors was studied. In ligated animals, IPC evoked an increase of monocyte chemoattractant protein-1 (MCP-1) and cytokine-induced neutrophil chemoattractant 1 (CXCL1) mRNA ( P < 0.01) and immunostaining ( P < 0.05), as well as a minor increase in VEGF immunostaining in the muscle endomysium 150 min postintervention. Further, collateral arteries from these animals showed an increased expression of MCP-1 (approximately twofold, P = 0.02). These effects were most evident in the group exposed to the high-frequency protocol (15 compressions/min). In contrast, IPC in sham-operated control animals evoked a modest initial upregulation of VEGF ( P = 0.01), MCP-1 ( P = 0.02), and CXCL1 ( P = 0.03) mRNA in the muscle without concomitant changes in protein levels. No changes in gene expression were observed in arteries isolated from sham animals. In conclusion, IPC acutely up-regulates the expression of important factors involved in vascular remodeling in the compressed muscle and collateral arteries in a model of hindlimb ischemia. These effects appear to be dependent on the compression frequency, such that a high compression frequency (15 compressions/min) evokes more consistent and robust effects compared with the frequency commonly employed clinically to treat patients with claudication (3 compressions/min).

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