scholarly journals Roles of Dkk2 in the Linkage from Muscle to Bone during Mechanical Unloading in Mice

2020 ◽  
Vol 21 (7) ◽  
pp. 2547 ◽  
Author(s):  
Naoyuki Kawao ◽  
Hironobu Morita ◽  
Shunki Iemura ◽  
Masayoshi Ishida ◽  
Hiroshi Kaji
Keyword(s):  
Skeletal Muscle ◽  
Shear Stress ◽  
Soleus Muscle ◽  
C2c12 Cells ◽  
Cyclooxygenase Inhibitors ◽  
Mrna Levels ◽  
Mineral Density ◽  
Humoral Factors ◽  
Mechanical Unloading ◽  
Dkk2 Expression

Mechanical unloading simultaneously induces muscle and bone loss, but its mechanisms are not fully understood. The interactions between skeletal muscle and bone have been recently noted. Although canonical wingless-related integration site (Wnt)/β-catenin signaling is crucial for bone metabolism, its roles in the muscle and bone interactions have remained unknown. Here, we performed comprehensive DNA microarray analyses to clarify humoral factors linking muscle to bone in response to mechanical unloading and hypergravity with 3 g in mice. We identified Dickkopf (Dkk) 2, a Wnt/β-catenin signaling inhibitor, as a gene whose expression was increased by hindlimb unloading (HU) and reduced by hypergravity in the soleus muscle of mice. HU significantly elevated serum Dkk2 levels and Dkk2 mRNA levels in the soleus muscle of mice whereas hypergravity significantly decreased those Dkk2 levels. In the simple regression analyses, serum Dkk2 levels were negatively and positively related to trabecular bone mineral density and mRNA levels of receptor activator of nuclear factor-kappa B ligand (RANKL) in the tibia of mice, respectively. Moreover, shear stress significantly suppressed Dkk2 mRNA levels in C2C12 cells, and cyclooxygenase inhibitors significantly antagonized the effects of shear stress on Dkk2 expression. On the other hand, Dkk2 suppressed the mRNA levels of osteogenic genes, alkaline phosphatase activity and mineralization, and it increased RANKL mRNA levels in mouse osteoblasts. In conclusion, we showed that muscle and serum Dkk2 levels are positively and negatively regulated during mechanical unloading and hypergravity in mice, respectively. An increase in Dkk2 expression in the skeletal muscle might contribute to disuse- and microgravity-induced bone and muscle loss.

Role of Dkk2 in the Muscle/bone Interaction of Androgen-Deficient Mice

2020 ◽  
Author(s):  
Shunki Iemura ◽  
Naoyuki Kawao ◽  
Masao Akagi ◽  
Hiroshi Kaji
Keyword(s):  
C2c12 Cells ◽  
Mrna Levels ◽  
Androgen Deficiency ◽  
Mineral Density ◽  
Trabecular Bone Mineral Density ◽  
Humoral Factors ◽  
Mouse Muscle ◽  
Canonical Wnt ◽  
Deficient Mice

AbstractAndrogen deficiency is known to cause both osteoporosis and sarcopenia. Myokines, humoral factors secreted from the skeletal muscles, have recently been getting attention as the key factors related to the interactions between muscle and bone. Dickkopf (Dkk) 2 is known as an inhibitor of canonical Wnt/β-catenin signaling, and Wnt/β-catenin signaling is crucial for the maintenance of muscle and bone. The present study was therefore performed to investigate the roles of Dkk2 in the alterations of muscle and bone of androgen-deficient mice with orchidectomy (ORX). ORX significantly enhanced Dkk2 mRNA levels, but not other Dkks and secreted frizzled related proteins, in the soleus muscles of mice. Moreover, ORX enhanced serum Dkk2 levels, but not Dkk2 mRNA levels in the tibial bone tissues, the white adipose tissues and liver of mice. In simple regression analyses, serum Dkk2 levels were negatively related to trabecular bone mineral density at the tibias in mice employed in the experiments. In vitro experiments, testosterone suppressed Dkk2 mRNA levels in mouse muscle C2C12 cells. In conclusion, we showed that androgen deficiency enhances Dkk2 expression and secretion in the muscles of mice. Dkk2 might be involved in androgen deficiency-induced muscle wasting and osteopenia as a myokine linking muscle to bone.

scholarly journals TWIST1 and TWIST2 regulate glycogen storage and inflammatory genes in skeletal muscle

2015 ◽  
Vol 224 (3) ◽  
pp. 303-313 ◽  
Author(s):  
Jonathan M Mudry ◽  
Julie Massart ◽  
Ferenc L M Szekeres ◽  
Anna Krook
Keyword(s):  
Skeletal Muscle ◽  
Metabolic Diseases ◽  
Glycogen Synthesis ◽  
C2c12 Cells ◽  
Acid Oxidation ◽  
Diabetic Patients ◽  
Mrna Levels ◽  
Intact Mouse ◽  
Mouse Muscle ◽  
The Impact

TWIST proteins are important for development of embryonic skeletal muscle and play a role in the metabolism of tumor and white adipose tissue. The impact of TWIST on metabolism in skeletal muscle is incompletely studied. Our aim was to assess the impact of TWIST1 and TWIST2 overexpression on glucose and lipid metabolism. In intact mouse muscle, overexpression of Twist reduced total glycogen content without altering glucose uptake. Expression of TWIST1 or TWIST2 reducedPdk4mRNA, while increasing mRNA levels ofIl6,Tnfα, andIl1β. Phosphorylation of AKT was increased and protein abundance of acetyl CoA carboxylase (ACC) was decreased in skeletal muscle overexpressing TWIST1 or TWIST2. Glycogen synthesis and fatty acid oxidation remained stable in C2C12 cells overexpressing TWIST1 or TWIST2. Finally, skeletal muscle mRNA levels remain unaltered inob/obmice, type 2 diabetic patients, or in healthy subjects before and after 3 months of exercise training. Collectively, our results indicate that TWIST1 and TWIST2 are expressed in skeletal muscle. Overexpression of these proteins impacts proteins in metabolic pathways and mRNA level of cytokines. However, skeletal muscle levels of TWIST transcripts are unaltered in metabolic diseases.

scholarly journals Role of Osteoglycin in the Linkage between Muscle and Bone

2012 ◽  
Vol 287 (15) ◽  
pp. 11616-11628 ◽  
Author(s):  
Ken-ichiro Tanaka ◽  
Erika Matsumoto ◽  
Yoshiko Higashimaki ◽  
Takenobu Katagiri ◽  
Toshitsugu Sugimoto ◽  
...  
Keyword(s):  
Transcriptional Activity ◽  
Type I Collagen ◽  
C2c12 Cells ◽  
Type I ◽  
Mrna Levels ◽  
Humoral Factors ◽  
Anabolic Activity ◽  
Morphogenetic Protein ◽  
Muscle Tissues

The interaction between muscle tissues and bone metabolism is incompletely understood. We hypothesized that there might be some humoral factors that are produced in muscle tissues and exhibit bone anabolic activity. We, therefore, performed comparative DNA microarray analysis between mouse myoblastic C2C12 cells transfected with either stable empty vector or ALK2 (R206H), the mutation that constitutively activates the bone morphogenetic protein (BMP) receptor, to search for muscle-derived bone anabolic factors. Twenty-five genes whose expression was decreased to <1/4, were identified; these included osteoglycin (OGN). Stable overexpression of OGN significantly decreased the levels of Runx2 and Osterix mRNA compared with those in cells transfected with vector alone in MC3T3-E1 cells. On the other hand, it significantly enhanced the levels of alkaline phosphatase (ALP), type I collagen (Col1), and osteocalcin (OCN) mRNA as well as β-catenin and mineralization. A reduction in endogenous OGN level showed the opposite effects to those of OGN overexpression in MC3T3-E1 and mouse calvarial osteoblastic cells. Transient OGN overexpression significantly suppressed the levels of Runx2, Osterix, ALP, Col1, and OCN mRNA induced by BMP-2 in C2C12 cells. The conditioned medium from OGN-overexpressed and OGN-suppressed myoblastic cells enhanced and decreased, respectively, the levels of ALP, Col1, and β-catenin in MC3T3-E1 cells. Moreover, OGN increased Smad3/4-responsive transcriptional activity as well as Col1 mRNA levels independently of endogenous TGF-β in these cells. In conclusion, this study suggests that OGN may be a crucial humoral bone anabolic factor that is produced by muscle tissues.

Skeletal muscle myostatin mRNA expression is fiber-type specific and increases during hindlimb unloading

1999 ◽  
Vol 277 (2) ◽  
pp. R601-R606 ◽  
Author(s):  
Christian J. Carlson ◽  
Frank W. Booth ◽  
Scott E. Gordon
Keyword(s):  
Skeletal Muscle ◽  
Muscle Mass ◽  
Soleus Muscle ◽  
Fiber Type ◽  
Weight Bearing ◽  
Mrna Abundance ◽  
Hindlimb Unloading ◽  
Negative Regulator ◽  
Type I ◽  
Mrna Levels

Transgenic mice lacking a functional myostatin (MSTN) gene demonstrate greater skeletal muscle mass resulting from muscle fiber hypertrophy and hyperplasia (McPherron, A. C., A. M. Lawler, and S.-J. Lee. Nature 387: 83–90, 1997). Therefore, we hypothesized that, in normal mice, MSTN may act as a negative regulator of muscle mass. Specifically, we hypothesized that the predominately slow (type I) soleus muscle, which demonstrates greater atrophy than the fast (type II) gastrocnemius-plantaris complex (Gast/PLT), would show more elevation in MSTN mRNA abundance during hindlimb unloading (HU). Surprisingly, MSTN mRNA was not detectable in weight-bearing or HU soleus muscle, which atrophied 42% by the 7th day of HU in female ICR mice. In contrast, MSTN mRNA was present in weight-bearing Gast/PLT muscle and was significantly elevated (67%) at 1 day but not at 3 or 7 days of HU. However, the Gast/PLT muscle had only atrophied 17% by the 7th day of HU. Because the soleus is composed only of type I and IIa fibers, whereas the Gast/PLT expresses type IId/x and IIb in addition to type I and IIa, it was necessary to perform a more careful analysis of the relationship between MSTN mRNA levels and myosin heavy-chain (MHC) isoform expression (as a marker of fiber type). A significant correlation ( r = 0.725, P < 0.0005) was noted between the percentage of MHC isoform IIb expression and MSTN mRNA abundance in several muscles of the mouse hindlimb. These results indicate that MSTN expression is not strongly associated with muscle atrophy induced by HU; however, it is strongly associated with MHC isoform IIb expression in normal muscle.

NFAT activation by membrane potential follows a calcium pathway distinct from other activity-related transcription factors in skeletal muscle cells

2008 ◽  
Vol 294 (3) ◽  
pp. C715-C725 ◽  
Author(s):  
Juan Antonio Valdés ◽  
Eduardo Gaggero ◽  
Jorge Hidalgo ◽  
Nancy Leal ◽  
Enrique Jaimovich ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Transcription Factors ◽  
Electrical Stimulation ◽  
Stimulus Frequency ◽  
Muscle Cells ◽  
C2c12 Cells ◽  
Skeletal Muscle Cells ◽  
Mrna Levels ◽  
Activated T Cells ◽  
Nfat Activation

Depolarization of skeletal muscle cells triggers intracellular Ca2+ signals mediated by ryanodine and inositol 1,4,5-trisphosphate (IP3) receptors. Previously, we have reported that K+-induced depolarization activates transcriptional regulators ERK, cAMP response element-binding protein, c- fos, c- jun, and egr-1 through IP3-dependent Ca2+ release, whereas NF-κB activation is elicited by both ryanodine and IP3 receptor-mediated Ca2+ signals. We have further shown that field stimulation with electrical pulses results in an NF-κB activation increase dependent of the amount of pulses and independent of their frequency. In this work, we report the results obtained for nuclear factor of activated T cells (NFAT)-mediated transcription and translocation generated by both K+ and electrical stimulation protocols in primary skeletal muscle cells and C2C12 cells. The Ca2+ source for NFAT activation is through release by ryanodine receptors and extracellular Ca2+ entry. We found this activation to be independent of the number of pulses within a physiological range of stimulus frequency and enhanced by long-lasting low-frequency stimulation. Therefore, activation of the NFAT signaling pathway differs from that of NF-κB and other transcription factors. Calcineurin enzyme activity correlated well with the relative activation of NFAT translocation and transcription using different stimulation protocols. Furthermore, both K+-induced depolarization and electrical stimulation increased mRNA levels of the type 1 IP3 receptor mediated by calcineurin activity, which suggests that depolarization may regulate IP3 receptor transcription. These results confirm the presence of at least two independent pathways for excitation-transcription coupling in skeletal muscle cells, both dependent on Ca2+ release and triggered by the same voltage sensor but activating different intracellular release channels.

scholarly journals New Intracellular Peptide Derived from Hemoglobin Alpha Chain Induces Glucose Uptake and Reduces Blood Glycemia

Pharmaceutics ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2175
Author(s):  
Renée N. O. Silva ◽  
Ricardo P. Llanos ◽  
Rosangela A. S. Eichler ◽  
Thiago B. Oliveira ◽  
Fábio C. Gozzo ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Adipose Tissue ◽  
Glucose Uptake ◽  
Knockout Mice ◽  
Conditional Knockout ◽  
C2c12 Cells ◽  
Yeast Cells ◽  
Epididymal Adipose Tissue ◽  
Mrna Levels ◽  
Akt Phosphorylation

Intracellular peptides were shown to derive from proteasomal degradation of proteins from mammalian and yeast cells, being suggested to play distinctive roles both inside and outside these cells. Here, the role of intracellular peptides previously identified from skeletal muscle and adipose tissues of C57BL6/N wild type (WT) and neurolysin knockout mice were investigated. In differentiated C2C12 mouse skeletal muscle cells, some of these intracellular peptides like insulin activated the expression of several genes related to muscle contraction and gluconeogenesis. One of these peptides, LASVSTVLTSKYR (Ric4; 600 µg/kg), administrated either intraperitoneally or orally in WT mice, decreased glycemia. Neither insulin (10 nM) nor Ric4 (100 µM) induced glucose uptake in adipose tissue explants obtained from conditional knockout mice depleted of insulin receptor. Ric4 (100 µM) similarly to insulin (100 nM) induced Glut4 translocation to the plasma membrane of C2C12 differentiated cells, and increased GLUT4 mRNA levels in epididymal adipose tissue of WT mice. Ric4 (100 µM) increased both Erk and Akt phosphorylation in C2C12, as well as in epididymal adipose tissue from WT mice; Erk, but not Akt phosphorylation was activated by Ric4 in tibial skeletal muscle from WT mice. Ric4 is rapidly degraded in vitro by WT liver and kidney crude extracts, such a response that is largely reduced by structural modifications such as N-terminal acetylation, C-terminal amidation, and substitution of Leu8 for DLeu8 (Ac-LASVSTV[DLeu]TSKYR-NH2; Ric4-16). Ric4-16, among several Ric4 derivatives, efficiently induced glucose uptake in differentiated C2C12 cells. Among six Ric4-derivatives evaluated in vivo, Ac-LASVSTVLTSKYR-NH2 (Ric4-2; 600 µg/kg) and Ac-LASVSTV[DLeu]TSKYR (Ric4-15; 600 µg/kg) administrated orally efficiently reduced glycemia in a glucose tolerance test in WT mice. The potential clinical application of Ric4 and Ric4-derivatives deserves further attention.

Skeletal muscle collagen type I and III mRNA, [corrected] prolyl 4-hydroxylase, and collagen in hypobaric trained rats

1996 ◽  
Vol 80 (6) ◽  
pp. 2226-2233 ◽  
Author(s):  
M. Perhonen ◽  
X. Han ◽  
W. Wang ◽  
J. Karpakka ◽  
T. E. Takala
Keyword(s):  
Skeletal Muscle ◽  
Soleus Muscle ◽  
Collagen Type ◽  
Mrna Level ◽  
Collagen Type I ◽  
Synthesis Rate ◽  
Type I ◽  
Mrna Levels ◽  
Edl Muscle ◽  
And Training

Skeletal muscle collagen expression was studied in normobaric sedentary (NS) and training (NT) and hypobaric sedentary (HS) and training (HT) rats after experimental periods of 10, 21, and 56 days. The weights of fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus muscles were increased between the experimental period of 21 and 56 days so that EDL weight was 57 (P < 0.01) and 36% (P < 0.05) higher in 56 days HS (56HS) and 56 days HT (56HT), respectively, than in 56 days NS (56NS). Soleus muscle weight was higher in 56HS (61%; P < 0.01) and in 56HT (27%; P < 0.05) than in 56NT. In EDL muscle, collagen type I mRNA level was lower in 56HT than in 56NS (36%; P < 0.05) and 56NT (44%; P < 0.01). In 56HT, collagen type III mRNA level was 39 (P < 0.01) and 42% (P < 0.05) lower than in 56NS and 56HS, respectively. In soleus muscle, prolyl 4-hydroxylase activity was greater (P < 0.05) in 56NT, 56HS, and 56HT than in 56NS. Total hydroxyproline content in EDL muscle was increased in 56HS and 56HT and in soleus muscle of 56HS. In conclusion, although collagen types I and III mRNA levels in EDL muscle decreased in 56HT, the prolyl 4-hydroxylase data suggest unchanged synthesis of total collagen. Exposure to hypobaric conditions as such, its combination to endurance training, as well as training in normobaric conditions increased prolyl 4-hydroxylation capacity in soleus muscle, which may indicate respective change in collagen synthesis rate.

scholarly journals Angiotensin-(1-7) Prevents Lipopolysaccharide-Induced Autophagy via the Mas Receptor in Skeletal Muscle

2020 ◽  
Vol 21 (24) ◽  
pp. 9344
Author(s):  
Juan Carlos Rivera ◽  
Johanna Abrigo ◽  
Franco Tacchi ◽  
Felipe Simon ◽  
Enrique Brandan ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Atrophy ◽  
B Cell Lymphoma ◽  
Mapk Signaling ◽  
C2c12 Cells ◽  
Skeletal Muscle Atrophy ◽  
Autophagic Flux ◽  
Mrna Levels ◽  
Mas Receptor ◽  
The Impact

Skeletal muscle atrophy, which occurs in lipopolysaccharide (LPS)-induced sepsis, causes a severe muscle function reduction. The increased autophagy contributes to sepsis-induced skeletal muscle atrophy in a model of LPS injection, increasing LC3II/LC3I ratio, autophagy flux, and autophagosomes. Angiotensin-(1-7) (Ang-(1-7)) has anti-atrophic effects via the Mas receptor in skeletal muscle. However, the impact of Ang-(1-7) on LPS-induced autophagy is unknown. In this study, we determined the effect of Ang-(1-7) on sepsis-induced muscle autophagy. C57BL6 wild-type (WT) mice and mice lacking the Mas receptor (KO Mas) were injected with LPS together with the systemic administration of Ang-(1-7) to determine autophagy in skeletal muscle. We also evaluated autophagy and p38 and c-Jun N-terminal kinase (JNK)activation. Our results show that Ang-(1-7) prevents LPS-induced autophagy in the diaphragm, tibialis anterior, and gastrocnemius of WT mice, which is demonstrated by a decrease in the LC3II/LC3I ratio and mRNA levels of lc3b and ctsl. This effect was lost in KO Mas mice, suggesting the role of the Mas receptor. The results in C2C12 cells show that Ang-(1-7) reduces several LPS-dependent effects, such as autophagy (LC3II/LC3I ratio, autophagic flux, and autophagosomes), activation of p38 and JNK, B-cell lymphoma-2 (BCL2) phosphorylation, and disassembly of the Beclin1/BCL2 complex. In conclusion, Ang-(1-7)/Mas receptor reduces LPS-induced autophagy in skeletal muscle. In vitro assays indicate that Ang-(1-7) prevents LPS-induced autophagy and modifies the MAPK signaling and the disassembly of a complex involved at the beginning of autophagy.

scholarly journals Nano-graphene oxide/polyurethane nanofibers: mechanically flexible and myogenic stimulating matrix for skeletal tissue engineering

2020 ◽  
Vol 11 ◽  
pp. 204173141990042 ◽  
Author(s):  
Seung Bin Jo ◽  
Uyanga Erdenebileg ◽  
Khandmaa Dashnyam ◽  
Guang-Zhen Jin ◽  
Jae-Ryung Cha ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Graphene Oxide ◽  
Myogenic Differentiation ◽  
C2c12 Cells ◽  
Dynamic Force ◽  
Mrna Levels ◽  
Differentiation Markers ◽  
Nanofibrous Scaffolds ◽  
Initial Adhesion ◽  
Nano Graphene

For skeletal muscle engineering, scaffolds that can stimulate myogenic differentiation of cells while possessing suitable mechanical properties (e.g. flexibility) are required. In particular, the elastic property of scaffolds is of importance which helps to resist and support the dynamic conditions of muscle tissue environment. Here, we developed highly flexible nanocomposite nanofibrous scaffolds made of polycarbonate diol and isosorbide-based polyurethane and hydrophilic nano-graphene oxide added at concentrations up to 8%. The nano-graphene oxide incorporation increased the hydrophilicity, elasticity, and stress relaxation capacity of the polyurethane-derived nanofibrous scaffolds. When cultured with C2C12 cells, the polyurethane–nano-graphene oxide nanofibers enhanced the initial adhesion and spreading of cells and further the proliferation. Furthermore, the polyurethane–nano-graphene oxide scaffolds significantly up-regulated the myogenic mRNA levels and myosin heavy chain expression. Of note, the cells on the flexible polyurethane–nano-graphene oxide nanofibrous scaffolds could be mechanically stretched to experience dynamic tensional force. Under the dynamic force condition, the cells expressed significantly higher myogenic differentiation markers at both gene and protein levels and exhibited more aligned myotubular formation. The currently developed polyurethane–nano-graphene oxide nanofibrous scaffolds, due to their nanofibrous morphology and high mechanical flexibility, along with the stimulating capacity for myogenic differentiation, are considered to be a potential matrix for future skeletal muscle engineering.

scholarly journals Neurogranin is expressed in mammalian skeletal muscle and inhibits calcineurin signaling and myoblast fusion

2019 ◽  
Vol 317 (5) ◽  
pp. C1025-C1033 ◽  
Author(s):  
Val A. Fajardo ◽  
Colton J. F. Watson ◽  
Kirsten N. Bott ◽  
Fereshteh Moradi ◽  
Lucas A. Maddalena ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Myogenic Differentiation ◽  
Vastus Lateralis ◽  
Critical Role ◽  
Myoblast Fusion ◽  
C2c12 Cells ◽  
C2c12 Myotubes ◽  
Mammalian Skeletal Muscle ◽  
Mrna Levels ◽  
Calcineurin Signaling

Calcineurin is a Ca2+/calmodulin (CaM)-dependent phosphatase that plays a critical role in promoting the slow fiber phenotype and myoblast fusion in skeletal muscle, thereby making calcineurin an attractive cellular target for enhancing fatigue resistance, muscle metabolism, and muscle repair. Neurogranin (Ng) is a CaM-binding protein thought to be expressed solely in brain and neurons, where it inhibits calcineurin signaling by sequestering CaM, thus lowering its cellular availability. Here, we demonstrate for the first time the expression of Ng protein and mRNA in mammalian skeletal muscle. Both protein and mRNA levels are greater in slow-oxidative compared with fast-glycolytic muscles. Coimmunoprecipitation of CaM with Ng in homogenates of C2C12 myotubes, mouse soleus, and human vastus lateralis suggests that these proteins physically interact. To determine whether Ng inhibits calcineurin signaling in muscle, we used Ng siRNA with C2C12 myotubes to reduce Ng protein levels by 60%. As a result of reduced Ng expression, C2C12 myotubes had enhanced CaM-calcineurin binding and calcineurin signaling as indicated by reduced phosphorylation of nuclear factor of activated T cells and increased utrophin mRNA. In addition, calcineurin signaling affects the expression of myogenin and stabilin-2, which are involved in myogenic differentiation and myoblast fusion, respectively. Here, we found that both myogenin and stabilin-2 were significantly elevated by Ng siRNA in C2C12 cells, concomitantly with an increased fusion index. Taken together, these results demonstrate the expression of Ng in mammalian skeletal muscle where it appears to be a novel regulator of calcineurin signaling.

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