Fusion between myoblasts and adult muscle fibers promotes remodeling of fibers into myotubes in vitro

Development ◽  
1990 ◽  
Vol 109 (1) ◽  
pp. 139-147 ◽  
Author(s):  
T.J. Hinterberger ◽  
K.F. Barald
Keyword(s):  
Satellite Cells ◽  
Adult Mouse ◽  
Muscle Fibers ◽  
Muscle Growth ◽  
Fibroblast Cell ◽  
C2c12 Cells ◽  
Rat Muscle ◽  
Do So

Muscle satellite cells are residual embryonic myoblast precursors responsible for muscle growth and regeneration. In order to examine the role of satellite cells in the initial events of muscle regeneration, we placed individual mature rat muscle fibers in vitro along with their satellite cells. When the satellite cells were allowed to proliferate, they produced populations of myoblasts that fused together to form myotubes on the laminin substrate. These myoblasts and myotubes also fused with the adult fibers. When they did so, the fibers lost their adult morphology, and by 8 days in vitro, essentially all of them were remodeled into structures resembling embryonic myotubes. However, when proliferating satellite cells were eliminated by exposure to cytosine arabinoside (araC), the vast majority of fibers retained their adult shape. Addition of C2C12 cells (a myoblast line derived from adult mouse satellite cells) to araC-treated fiber cultures resulted in their fusion with the rat muscle fibers and restored the ability of the fibers to remodel, whereas addition of either a fibroblast cell line or a transformed, non-fusing variant of C2C12 cells, or addition of conditioned medium from C2C12 cells, failed to do so. These results imply that myoblast fusion is responsible for triggering adult fiber remodeling in vitro.

The COX-2 pathway regulates growth of atrophied muscle via multiple mechanisms

2006 ◽  
Vol 290 (6) ◽  
pp. C1651-C1659 ◽  
Author(s):  
Brenda A. Bondesen ◽  
Stephen T. Mills ◽  
Grace K. Pavlath
Keyword(s):  
Muscle Mass ◽  
Muscle Regeneration ◽  
Muscle Growth ◽  
Cell Activity ◽  
Hindlimb Suspension ◽  
Normal Muscle ◽  
Cox 2 ◽  
Proliferation In Vitro

Loss of muscle mass occurs with disease, injury, aging, and inactivity. Restoration of normal muscle mass depends on myofiber growth, the regulation of which is incompletely understood. Cyclooxygenase (COX)-2 is one of two isoforms of COX that catalyzes the synthesis of prostaglandins, paracrine hormones that regulate diverse physiological and pathophysiological processes. Previously, we demonstrated that the COX-2 pathway regulates early stages of myofiber growth during muscle regeneration. However, whether the COX-2 pathway plays a common role in adult myofiber growth or functions specifically during muscle regeneration is unknown. Therefore, we examined the role of COX-2 during myofiber growth following atrophy in mice. Muscle atrophy was induced by hindlimb suspension (HS) for 2 wk, followed by a reloading period, during which mice were treated with either the COX-2-selective inhibitor SC-236 (6 mg·kg−1·day−1) or vehicle. COX-2 protein was expressed and SC-236 attenuated myofiber growth during reloading in both soleus and plantaris muscles. Attenuated myofiber growth in the soleus was associated with both decreased myonuclear addition and decreased inflammation, whereas neither of these processes mediated the effects of SC-236 on plantaris growth. In addition, COX-2−/− satellite cells exhibited impaired activation/proliferation in vitro, suggesting direct regulation of muscle cell activity by COX-2. Together, these data suggest that the COX-2 pathway plays a common regulatory role during various types of muscle growth via multiple mechanisms.

scholarly journals FGF-2–dependent signaling activated in aged human skeletal muscle promotes intramuscular adipogenesis

2021 ◽  
Vol 118 (37) ◽  
pp. e2021013118 ◽  
Author(s):  
Sebastian Mathes ◽  
Alexandra Fahrner ◽  
Umesh Ghoshdastider ◽  
Hannes A. Rüdiger ◽  
Michael Leunig ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Transcriptional Activation ◽  
Human Skeletal Muscle ◽  
Muscle Growth ◽  
Muscle Cells ◽  
Adeno Associated Virus ◽  
Adult Skeletal Muscle

Aged skeletal muscle is markedly affected by fatty muscle infiltration, and strategies to reduce the occurrence of intramuscular adipocytes are urgently needed. Here, we show that fibroblast growth factor-2 (FGF-2) not only stimulates muscle growth but also promotes intramuscular adipogenesis. Using multiple screening assays upstream and downstream of microRNA (miR)-29a signaling, we located the secreted protein and adipogenic inhibitor SPARC to an FGF-2 signaling pathway that is conserved between skeletal muscle cells from mice and humans and that is activated in skeletal muscle of aged mice and humans. FGF-2 induces the miR-29a/SPARC axis through transcriptional activation of FRA-1, which binds and activates an evolutionary conserved AP-1 site element proximal in the miR-29a promoter. Genetic deletions in muscle cells and adeno-associated virus–mediated overexpression of FGF-2 or SPARC in mouse skeletal muscle revealed that this axis regulates differentiation of fibro/adipogenic progenitors in vitro and intramuscular adipose tissue (IMAT) formation in vivo. Skeletal muscle from human donors aged >75 y versus <55 y showed activation of FGF-2–dependent signaling and increased IMAT. Thus, our data highlights a disparate role of FGF-2 in adult skeletal muscle and reveals a pathway to combat fat accumulation in aged human skeletal muscle.

scholarly journals miR-194-5p negatively regulates the proliferation and differentiation of rabbit skeletal muscle satellite cells

2020 ◽  
Author(s):  
Yu Shi ◽  
Xudong Mao ◽  
Mingcheng Cai ◽  
Shenqiang Hu ◽  
Xiulan Lai ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Satellite Cells ◽  
Mammalian Species ◽  
Muscle Growth ◽  
Luciferase Reporter ◽  
Stem Cell Population ◽  
Muscle Satellite Cells ◽  
Skeletal Muscle Satellite Cells ◽  
Proliferation And Differentiation

Abstract Skeletal muscle satellite cells (SMSCs), also known as a multipotential stem cell population, play a crucial role during muscle growth and regeneration. In recent years, numerous miRNAs have been associated with the proliferation and differentiation of SMSCs in a number of mammalian species; however, the regulatory mechanisms of miR-194-5p in rabbit SMSCs still remain scarce. In this study, miR-194-5p was first observed to be highly expressed in the rabbit leg muscle. Furthermore, both the mimics and inhibitor of miR-194-5p were used to explore its role in the proliferation and differentiation of rabbit SMSCs cultured in vitro. Results from both EdU and CCK8 assays showed that miR-194-5p inhibited the proliferation of SMSCs. Meanwhile, Mef2c was identified as a target gene of miR-194-5p based on the dual-luciferase reporter assay results. In addition, upregulation of miR-194-5p decreased the expression levels of Mef2c and MyoG during rabbit SMSCs differentiation on Days 3 and 7 of in vitro culture. Taken together, these data demonstrated that miR-194-5p negatively regulates the proliferation and differentiation of rabbit SMSCs by targeting Mef2c.

scholarly journals HDAC4 Regulates the Proliferation, Differentiation and Apoptosis of Chicken Skeletal Muscle Satellite Cells

Animals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 84 ◽  
Author(s):  
Jing Zhao ◽  
Xiaoxu Shen ◽  
Xinao Cao ◽  
Haorong He ◽  
Shunshun Han ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Satellite Cells ◽  
Muscle Development ◽  
Critical Role ◽  
Muscle Growth ◽  
Positive Role ◽  
Muscle Satellite Cells ◽  
Skeletal Muscle Satellite Cells ◽  
Chicken Skeletal Muscle

The development of skeletal muscle satellite cells (SMSCs) is a complex process that could be regulated by many genes. Previous studies have shown that Histone Deacetylase 4 (HDAC4) plays a critical role in cell proliferation, differentiation, and apoptosis in mouse. However, the function of HDAC4 in chicken muscle development is still unknown. Given that chicken is a very important meat-producing animal that is also an ideal model to study skeletal muscle development, we explored the functions of HDAC4 in chicken SMSCs after the interference of HDAC4. The results showed that HDAC4 was enriched in embryonic skeletal muscle, and it was highly expressed in embryonic muscle than in postnatal muscles. Meanwhile, knockdown of HDAC4 could significantly inhibit the proliferation and differentiation of chicken SMSCs but had no effect on the apoptosis of SMSCs as observed in a series of experiment conducted in vitro. These results indicated that HDAC4 might play a positive role in chicken skeletal muscle growth and development.

Possible role of gap junctions in activation of myometrium during parturition

1978 ◽  
Vol 235 (5) ◽  
pp. C168-C179 ◽  
Author(s):  
R. E. Garfield ◽  
S. M. Sims ◽  
M. S. Kannan ◽  
E. E. Daniel
Keyword(s):  
Smooth Muscle ◽  
Gap Junctions ◽  
Freeze Fracture ◽  
Normal Pregnancy ◽  
Pregnant Rats ◽  
Junction Formation ◽  
Synchronous Contraction ◽  
Do So

Gap junctions between smooth muscle cells of the myometrium of pregnant rats were found only immediately prior to, during and immediately after parturition by quantitative thin-section and freeze-fracture microscopy. Ovariectomy of 16- to 17-days-pregnant rats resulted in premature termination of pregnancy and the appearance of gap junctions. Methods that prolonged normal pregnancy in rats or maintained pregnancy in ovariectomized animals (progesterone treatment) prevented the appearance of gap junctions. Gap junctions formed in tissues incubated for 24--96 h in vitro without any hormonal influence. We propose that gap junctions are essential for normal labor and delivery for synchronous contraction of the muscle of the uterus. We present a model for control of parturition that may apply to other animals including humans. The model proposes: 1) the possible roles progesterone, prostaglandins, or estrogens may play in initiating gap-junction formation; 2) that the formation of gap junctions is a necessary step in activation of the myometrium leading to labor; and 3) that agents used to stimulate or inhibit labor may do so by affecting gap junctions.

scholarly journals Identification of a talin binding site in the cytoskeletal protein vinculin.

1989 ◽  
Vol 109 (6) ◽  
pp. 2917-2927 ◽  
Author(s):  
P Jones ◽  
P Jackson ◽  
G J Price ◽  
B Patel ◽  
V Ohanion ◽  
...  
Keyword(s):  
Amino Acids ◽  
In Vitro Transcription ◽  
Binding Activity ◽  
Cytoskeletal Protein ◽  
Translation System ◽  
Cos Cells ◽  
Cell Matrix ◽  
Do So

Binding of the cytoskeletal protein vinculin to talin is one of a number of interactions involved in linking F-actin to cell-matrix junctions. To identify the talin binding domain in vinculin, we expressed the NH2-terminal region of the molecule encoded by two closely similar, but distinct vinculin cDNAs, using an in vitro transcription translation system. The 5' Eco RI-Bam HI fragment of a partial 2.89-kb vinculin cDNA encodes a 45-kD polypeptide containing the first 398 amino acids of the molecule. The equivalent restriction enzyme fragment of a second vinculin cDNA (cVin5) lacks nucleotides 746-867, and encodes a 41-kD polypeptide missing amino acids 167-207. The radiolabeled 45-kD vinculin polypeptide bound to microtiter wells coated with talin, but not BSA, and binding was inhibited by unlabeled vinculin. In contrast, the 41-kD vinculin polypeptide was devoid of talin binding activity. The role of residues 167-207 in talin binding was further analyzed by making a series of deletions spanning this region, each deletion of seven amino acids contiguous with the next. Loss of residues 167-173, 174-180, 181-187, 188-194, or 195-201 resulted in a marked reduction in talin binding activity, although loss of residues 202-208 had much less effect. When the 45-kD vinculin polypeptide was expressed in Cos cells, it localized to cell matrix junctions, whereas the 41-kD polypeptide, lacking residues 167-207, was unable to do so. Interestingly, some deletion mutants with reduced ability to bind talin in vitro, were still able to localize to cell matrix junctions.

scholarly journals Effects of isoleucine on glucose uptake through the enhancement of muscular membrane concentrations of GLUT1 and GLUT4 and intestinal membrane concentrations of Na+/glucose co-transporter 1 (SGLT-1) and GLUT2

2016 ◽  
Vol 116 (4) ◽  
pp. 593-602 ◽  
Author(s):  
Shihai Zhang ◽  
Qing Yang ◽  
Man Ren ◽  
Shiyan Qiao ◽  
Pingli He ◽  
...  
Keyword(s):  
Glucose Uptake ◽  
Metabolic Diseases ◽  
Average Daily Gain ◽  
Muscle Growth ◽  
C2c12 Cells ◽  
Whole Body ◽  
Human Beings ◽  
Intestinal Membrane ◽  
Red Muscle

AbstractKnowledge of regulation of glucose transport contributes to our understanding of whole-body glucose homoeostasis and human metabolic diseases. Isoleucine has been reported to participate in regulation of glucose levels in many studies; therefore, this study was designed to examine the effect of isoleucine on intestinal and muscular GLUT expressions. In an animal experiment, muscular GLUT and intestinal GLUT were determined in weaning pigs fed control or isoleucine-supplemented diets. Supplementation of isoleucine in the diet significantly increased piglet average daily gain, enhanced GLUT1 expression in red muscle and GLUT4 expression in red muscle, white muscle and intermediate muscle (P<0·05). In additional, expressions of Na+/glucose co-transporter 1 and GLUT2 were up-regulated in the small intestine when pigs were fed isoleucine-supplemented diets (P<0·05). C2C12 cells were used to examine the expressions of muscular GLUT and glucose uptake in vitro. In C2C12 cells supplemented with isoleucine in the medium, cellular 2-deoxyglucose uptake was increased (P<0·05) through enhancement of the expressions of GLUT4 and GLUT1 (P<0·05). The effect of isoleucine was greater than that of leucine on glucose uptake (P<0·05). Compared with newborn piglets, 35-d-old piglets have comparatively higher GLUT4, GLUT2 and GLUT5 expressions. The results of this study demonstrated that isoleucine supplementation enhanced the intestinal and muscular GLUT expressions, which have important implications that suggest that isoleucine could potentially increase muscle growth and intestinal development by enhancing local glucose uptake in animals and human beings.

ROLE OF THE MESENCHYME IN THE INDUCTION OF THE RAT PROSTATE GLAND BY ANDROGENS IN ORGAN CULTURE

1979 ◽  
Vol 82 (1) ◽  
pp. 171-NP ◽  
Author(s):  
ILSE LASNITZKI ◽  
TAKEO MIZUNO
Keyword(s):  
Organ Culture ◽  
De Novo ◽  
Prostate Gland ◽  
Young Male ◽  
Free Medium ◽  
Foetal Rat ◽  
Rat Prostate ◽  
Do So

SUMMARY Rat prostate glands are induced de novo by androgens in 16·5-day-old male and female urogenital sinuses in vitro as epithelial buds projecting into the surrounding mesenchyme. The role of the mesenchyme in this process has been investigated in various epithelial-mesenchymal recombinations in organ culture. Isolated epithelium did not form buds but required the presence of the mesenchyme to do so. This requirement seemed to be specific; in the presence of testosterone or dihydrotestosterone only urogenital mesenchyme increased cell division in the urogenital epithelium and stimulated prostatic bud formation. In contrast, heterotypic mesenchyme did not affect epithelial mitosis and failed to induce buds while heterotypic epithelia did not respond to urogenital mesenchyme. In recombinants of urogenital mesenchyme pretreated with androgen and untreated urogenital epithelium, grown in androgen-free medium, the majority of explants developed prostatic buds while only a few buds were formed from epithelium pretreated with androgen when it was recombined with untreated mesenchyme. The role of the mesenchyme in the loss of androgen responsiveness of the older female sinuses was examined in heterochronic recombinants. It was found that the old female mesenchyme failed to induce buds in young epithelium while young male or female mesenchymes induced them in the old female epithelium. The results suggest that the urogenital mesenchyme is essential for the initiation of the foetal rat prostate gland and that it may be a target for androgens and complement or mediate their effect on the epithelium.

scholarly journals Skeletal Myogenic Progenitors Originating from Embryonic Dorsal Aorta Coexpress Endothelial and Myogenic Markers and Contribute to Postnatal Muscle Growth and Regeneration

1999 ◽  
Vol 147 (4) ◽  
pp. 869-878 ◽  
Author(s):  
Luciana De Angelis ◽  
Libera Berghella ◽  
Marcello Coletta ◽  
Laura Lattanzi ◽  
Malvina Zanchi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Satellite Cells ◽  
Developmental Stages ◽  
Vascular System ◽  
Muscle Growth ◽  
Paraxial Mesoderm ◽  
Dorsal Aorta ◽  
Myogenic Cells ◽  
Adult Skeletal Muscle

Skeletal muscle in vertebrates is derived from somites, epithelial structures of the paraxial mesoderm, yet many unrelated reports describe the occasional appearance of myogenic cells from tissues of nonsomite origin, suggesting either transdifferentiation or the persistence of a multipotent progenitor. Here, we show that clonable skeletal myogenic cells are present in the embryonic dorsal aorta of mouse embryos. This finding is based on a detailed clonal analysis of different tissue anlagen at various developmental stages. In vitro, these myogenic cells show the same morphology as satellite cells derived from adult skeletal muscle, and express a number of myogenic and endothelial markers. Surprisingly, the latter are also expressed by adult satellite cells. Furthermore, it is possible to clone myogenic cells from limbs of mutant c-Met−/− embryos, which lack appendicular muscles, but have a normal vascular system. Upon transplantation, aorta-derived myogenic cells participate in postnatal muscle growth and regeneration, and fuse with resident satellite cells. The potential of the vascular system to generate skeletal muscle cells may explain observations of nonsomite skeletal myogenesis and raises the possibility that a subset of satellite cells may derive from the vascular system.

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