Development Of Skeletal Muscle Cells Research Articles

Regulatory Role of Nfix Gene in Sheep Skeletal Muscle Cell Development and Its Interaction Mechanism with MSTN.

Skeletal muscle development is crucial for livestock production, and understanding the molecular mechanisms involved is essential for enhancing muscle growth in sheep. This study aimed to investigate the role of Nfix, a member of the nuclear factor I (NFI) family, in regulating muscle development in sheep, filling a significant gap in the current understanding of Nfix deficiency and its impact on skeletal muscle growth, as no similar studies have been reported in this species. Bioinformatic analysis, including temporal analysis of transcriptome data, identified Nfix as a potential target gene for muscle growth regulation. The effects of Nfix overexpression and knockout on the proliferation and differentiation of sheep skeletal muscle cells were investigated. Changes in the expression of associated marker genes were assessed to explore the regulatory link between Nfix and the myostatin (MSTN) gene. Additionally, target miRNAs for Nfix and MSTN were predicted using online databases such as miRWalk, resulting in the construction of an Nfix-miRNA-MSTN interactive regulatory network. The findings revealed that Nfix promotes the proliferation and differentiation of sheep skeletal muscle cells, with further analysis indicating that Nfix may regulate muscle cell development by modulating MSTN expression. This study provides preliminary insights into the function of Nfix in sheep skeletal muscle development and its regulatory interactions, addressing a critical knowledge gap regarding Nfix deficiency and its implications for muscle growth. These findings contribute to a better understanding of muscle biology in sheep and provide a theoretical foundation for future research into the regulatory mechanisms governing muscle development.

CD36 deficiency inhibits proliferation by cell cycle control in skeletal muscle cells.

Obesity-related muscular dysfunction and relative muscle atrophy affect an increasing number of people. Elucidating the molecular mechanisms of skeletal muscle cell development and growth may contribute to the maintenance of skeletal muscle mass in obesity. Fatty acid translocase (FAT/CD36), as a long-chain fatty acid transport protein, is crucial for lipid metabolism and signaling. CD36 is known to function in myogenic differentiation, and whether it affects the proliferation of skeletal muscle cells and the underlying mechanisms remain unclear. In this study, the effect of CD36 deficiency on skeletal muscle cell viability and proliferation was examined using C2C12 myoblasts. Results showed that the deletion of CD36 enhanced the inhibitory effect of PA on the proliferation and the promotion of apoptosis in skeletal muscle cells. Intriguingly, the silencing of CD36 suppressed cell proliferation by preventing the cell cycle from the G0/G1 phase to the S phase in a cyclin D1/CDK4-dependent manner. Overall, we demonstrated that CD36 was involved in skeletal muscle cell proliferation by cell cycle control, and these findings might facilitate the treatment of obesity-related muscle wasting.

Approaches to characterize the transcriptional trajectory of human myogenesis.

Human pluripotent stem cells (hPSCs) have attracted considerable interest in understanding the cellular fate determination processes and modeling a number of intractable diseases. In vitro generation of skeletal muscle tissues using hPSCs provides an essential model to identify the molecular functions and gene regulatory networks controlling the differentiation of skeletal muscle progenitor cells. Such a genetic roadmap is not only beneficial to understanding human myogenesis but also to decipher the molecular pathology of many skeletal muscle diseases. The combination of established human in vitro myogenesis protocols and newly developed molecular profiling techniques offers extensive insight into the molecular signatures for the development of normal and disease human skeletal muscle tissues. In this review, we provide a comprehensive overview of the current progress of in vitro skeletal muscle generation from hPSCs and relevant examples of the transcriptional landscape and disease-related transcriptional aberrations involving signaling pathways during the development of skeletal muscle cells.

CircARID1A regulates mouse skeletal muscle regeneration by functioning as a sponge of miR-6368.

The noncoding RNAs play important role in growth and development of mammalian skeletal muscle. Recent work has shown that circRNAs are abundant in skeletal muscle tissue, with significant changes in their expression patterns during muscle development and aging. We identified a novel circRNA called circARID1A that is highly expressed in mice skeletal muscle compare to its linear transcript. Experiments shown that circARID1A significantly inhibited the process of C2C12 cell proliferation and promoted its differentiation. Interactions between circRNA and miRNA were screened by miRNA gene chip sequencing. The results indicated that circARID1A can sponge miR-6368, which was further verified by miRNA sensor and other experiments. Besides, miR-6368 is a commonly expressed miRNA that regulates the expression of several target genes including Tlr4. A mouse model of skeletal muscle injury was successfully established to explore the role of circARID1A in skeletal muscle development and regeneration in vivo. Moreover, we found the overexpression of circARID1A significantly promoted the regeneration of skeletal muscle. The results of our study suggest that circARID1A may regulate skeletal muscle cell development and regeneration by sponging miR-6368.

Textured soy protein scaffolds enable the generation of three-dimensional bovine skeletal muscle tissue for cell-based meat

Cell-based meat (CBM) production is a promising technology that could generate meat without the need of animal agriculture. The generation of tissue requires a three-dimensional (3D) scaffold to provide support to the cells and mimic the extracellular matrix (ECM). For CBM, the scaffold needs to be edible and have suitable nutritional value and texture. Here, we demonstrate the use of textured soy protein—an edible porous protein-based biomaterial—as a novel CBM scaffold that can support cell attachment and proliferation to create a 3D engineered bovine muscle tissue. The media composition was optimized for 3D bovine satellite cell (BSC) proliferation and differentiation by adding myogenic-related growth factors. Myogenesis of several cell combinations was compared, and elevated myogenesis and ECM deposition were shown in co-culture of BSCs with bovine smooth muscle cells and tri-cultures of BSCs, bovine smooth muscle cells and bovine endothelial cells. The expression of proteins associated with ECM gene sets was increased in the co-culture compared with BSC monoculture. Volunteers tasted the product after cooking and noted its meaty flavour and sensorial attributes, achieving the goal of replicating the sensation and texture of a meat bite. This approach represents a step forward for the applied production of CBM as a food product. Animal skeletal muscle cell culture has the potential to provide new protein sources without the need for conventional animal agriculture. Ben-Ayre et. al. address one of the challenges of growing cell-based meat in vitro by using textured soy protein as an extracellular matrix scaffold. This approach allowed three-dimensional skeletal muscle cell development to produce a meat-like product for human consumption.

Structural Basis for the Distinct Membrane Binding Activity of the Homologous C2A Domains of Myoferlin and Dysferlin

Dysferlin has been implicated in acute membrane repair processes, whereas myoferlin's activity is maximal during the myoblast fusion stage of early skeletal muscle cell development. Both proteins are similar in size and domain structure; however, despite the overall similarity, myoferlin's known physiological functions do not overlap with those of dysferlin. Here we present for the first time the X‐ray crystal structure of human myoferlin C2A to 1.9 Å resolution bound to two divalent cations, and compare its three-dimensional structure and membrane binding activities to that of dysferlin C2A. We find that while dysferlin C2A binds membranes in a Ca2+-dependent manner, Ca2+ binding was the rate-limiting kinetic step for this interaction. Myoferlin C2A, on the other hand, binds two calcium ions with an affinity 3-fold lower than that of dysferlin C2A; and, surprisingly, myoferlin C2A binds only marginally to phospholipid mixtures with a high fraction of phosphatidylserine.

Roles of folate in skeletal muscle cell development and functions.

Folate is the generic term for both naturally occurring food folate and folic acid, the fully oxidized monoglutamate form of the vitamin that is used in dietary supplements and fortified foods. It is a water-soluble vitamin B9 and is important for health, growth, and development. As a precursor of various cofactors, folate is required for one-carbon donors in the synthesis of DNA bases and other essential biomolecules. A lack of dietary folate can lead to folate deficiency and can therefore result in several health problems, including macrocytic anemia, elevated plasma homocysteine, cardiovascular disease, birth defects, carcinogenesis, muscle weakness, and difficulty in walking. Several studies have implied that folate might exert a positive effect on skeletal muscle development. However, the precise effects of folate in skeletal muscle development are still poorly understood. Thus, this review provides an updated discussion of the roles of folate in skeletal muscle cell development and the effects of folic acid supplementation on the functions of skeletal muscle cells.

Folic acid is necessary for proliferation and differentiation of C2C12 myoblasts.

Folic acid, a water soluble B vitamin, plays an important role in cellular metabolic activities, such as functioning as a cofactor in one-carbon metabolism for DNA and RNA synthesis as well as nucleotide and amino acid biosynthesis in the body. A lack of dietary folic acid can lead to folic acid deficiency and result in several health problems, including macrocytic anemia, elevated plasma homocysteine, cardiovascular disease, birth defects, carcinogenesis, muscle weakness, and walking difficulty. However, the effect of folic acid deficiency on skeletal muscle development and its molecular mechanisms are unknown. We, therefore, investigated the effect of folic acid deficiency on myogenesis in skeletal muscle cells and found that folic acid deficiency induced proliferation inhibition and cell cycle breaking as well as cellular senescence in C2C12 myoblasts, implying that folic acid deficiency influences skeletal muscle development. Folic acid deficiency also inhibited differentiation of C2C12 myoblasts and induced deregulation of the cell cycle exit and many cell cycle regulatory genes. It inhibited expression of muscle-specific marker MyHC as well as myogenic regulatory factor (myogenin). Moreover, immunocytochemistry and Western blot analyses revealed that DNA damage was more increased in folic acid-deficient medium-treated differentiating C2C12 cells. Furthermore, we found that folic acid resupplementation reverses the effect on the cell cycle and senescence in folic acid-deficient C2C12 myoblasts but does not reverse the differentiation of C2C12 cells. Altogether, the study results suggest that folic acid is necessary for normal development of skeletal muscle cells.

Myogenic Maturation by Optical-Training in Cultured Skeletal Muscle Cells.

Optogenetic techniques are powerful tools for manipulating biological processes in identified cells using light under high temporal and spatial resolutions. Here, we describe an optogenetic training strategy to promote morphological maturation and functional development of skeletal muscle cells in vitro. Optical stimulation with a rhythmical frequency facilitates specific structural alignment of sarcomeric proteins. Optical stimulation also depolarizes the membrane potential, and induces contractile responses in synchrony with the given pattern of light pulses. These results suggest that optogenetic techniques can be employed to manipulate activity-dependent processes during myogenic development and control contraction of photosensitive skeletal muscle cells with high temporal and special precision.

MicroRNA-128 regulates the proliferation and differentiation of bovine skeletal muscle satellite cells by repressing Sp1.

MicroRNAs (miRNAs) play essential roles in muscle cell proliferation and differentiation. The muscle-specific miRNAs miR-1 and miR-206 have been shown to regulate muscle development and promote myogenic differentiation; however, it is likely that a number of other miRNAs play important roles in regulating myogenesis as well. microRNA-128 (miR-128) has been reported to be highly expressed in brain and skeletal muscle, and we found that miR-128 is also up-regulated during bovine skeletal muscle satellite cell differentiation using microarray analysis and qRT-PCR. However, little is known about the functions of miR-128 in bovine skeletal muscle satellite cell development. In this study, we investigated the biological functions of miR-128 in bovine skeletal muscle cell development. Using a dual-luciferase reporter assay, we confirmed that miR-128 regulates the Sp1 gene. Over-expression of miR-128 reduced Sp1 protein levels and inhibited muscle satellite cell proliferation and differentiation. Inhibition of miR-128 increased Sp1 protein levels and promoted muscle satellite cell differentiation but also suppressed proliferation. Changes in miR-128 and Sp1 expression levels also affected the protein levels of MyoD and CDKN1A. Sp1, an activator of MyoD and a suppressor of CDKN1A, plays an important role in bovine muscle cell proliferation and differentiation. The results of our study reveal a mechanism by which miR-128 regulates bovine skeletal muscle satellite cell proliferation and myogenic differentiation via Sp1.

The role of microRNA-1 and microRNA-206 in the proliferation and differentiation of bovine skeletal muscle satellite cells.

MicroRNAs (miRNAs) have been found to play essential roles in muscle cell proliferation and differentiation. MicroRNA-1 (miR-1) and microRNA-206 (miR-206), which are similar and have the same seed sequence, have specific roles in modulating skeletal muscle proliferation and differentiation in vitro and in vivo. However, there is no information about their function during bovine skeletal muscle satellite cell development. In this study, the profiles of miR-1 and miR-206 and their biological functions in bovine skeletal muscle cell development was investigated. The target genes were predicted, and we used a dual-luciferase reporter assay to demonstrate that miR-1 and miR-206 directly targeted the 3' untranslated region (3'UTR) of paired-box transcription factor Pax7 and histone deacetylase 4 (HDAC4). We showed that miR-1 and miR-206 facilitate bovine skeletal muscle satellite cell myogenic differentiation by restricting the expression of their target gene and that inhibition of miR-1 and miR-206 increased the Pax7 and HDAC4 protein levels and substantially enhanced satellite cell proliferation. Therefore, our results revealed the mechanism in which miR-1 and miR-206 positively regulate bovine skeletal muscle satellite cell myogenic differentiation via Pax7 and HDAC4 downregulation.

Transcriptional profiling of bovine muscle-derived satellite cells during differentiation in vitro by high throughput RNA sequencing.

In this study, we utilized high throughput RNA sequencing to obtain a comprehensive gene expression profile of muscle-derived satellite cells (MDSCs) upon induction of differentiation. MDSCs were cultured in vitro and RNA was extracted for sequencing prior to differentiation (MDSC-P), and again during the early and late differentiation (MDSC-D1, and MDSC-D3, respectively) stages. Sequence tags were assembled and analyzed by digital gene expression profile to screen for differentially expressed genes, Gene Ontology annotation, and pathway enrichment analysis. Quantitative real-time PCR was used to confirm the results of RNA sequencing. Our results indicate that certain of genes were changed during skeletal muscle cell development, cell cycle progression, and cell metabolism during differentiation of bovine MDSCs. Furthermore, we identified certain genes that could be used as novel candidates for future research of muscle development. Additionally, the sequencing results indicated that lipid metabolism might be the predominant cellular process that occurs during MDSC differentiation.

Organization of organelles and VAMP-associated vesicular transport systems in differentiating skeletal muscle cells

Vesicular transport plays an important role in the regulation of cellular function and differentiation of the cell, and intracellular vesicles play a role in the delivery of membrane components and in sorting membrane proteins to appropriate domains in organelles and the plasma membrane. Research on vesicular transport in differentiating cells has mostly focused on neurons and epithelial cells, and few such studies have been carried out on skeletal muscle cells. Skeletal muscle cells have specialized organelles and plasma membrane domains, including T-tubules, sarcoplasmic reticulum, neuromuscular junctions, and myotendinous junctions. The differentiation of skeletal muscle cells is achieved by multiple steps, i.e., proliferation of myoblasts, formation of myotubes by cell-cell fusion, and maturation of myotubes into myofibers. Systematic vesicular transport is expected to play a role in the maintenance and development of skeletal muscle cells. Here, we review a map of the vesicular transport system during the differentiation of skeletal muscle cells. The characteristics of organelle arrangement in myotubes are described according to morphological studies. Vesicular transport in myotubes is explained by the expression profiles of soluble N-ethylmaleimide-sensitive factor attachment protein receptor proteins.

Effect of weak static magnetic fields on the development of cultured skeletal muscle cells.

We studied the effect produced on the development and functional activity of skeletal muscle cells from newborn Wistar rats in primary culture by weak static magnetic fields (WSMF; 60-400 µT) with a high capacity of penetrating the biological media. To reduce the impact of external magnetic fields, cells were cultured at 37 °C in a multilayered shielding chamber with the attenuation coefficient equal to 160. WSMF inside the chamber was created by a circular permanent magnet. We found that the application of WSMF with the magnetic field strength only a few times that of the geomagnetic field can accelerate the development of skeletal muscle cells, resulting in the formation of multinuclear hypertrophied myotubes. WSMF was shown to induce 1.5- to 3.5-fold rise in the concentration of intracellular calcium [Ca(2+)]i due to the release of Ca(2+) from the sarcoplasmic reticulum (SR) through ryanodine receptors (RyR), which increases in the maturation of myotubes. We also found that fully differentiated myotubes at late stages of development were less sensitive to WSMF, manifesting a gradual decrease in the frequency of contractions. However, myotubes at the stage when electromechanical coupling was forming dramatically reduced the frequency of contractions during the first minutes of their exposure to WSMF.

Skeletal Muscle Characteristics of Broiler Chickens under Modified Incubation Factors

Four groups of broiler chicken hybrid ( Ross 308) eggs were incubated under different temperature and light conditions to assess the effects of both variables on musculature development. During the incubation, the first group was the control and the eggs were incubated at a temperature of 37.8 °C without light, the second group was exposed to increased temperature, while the third group was exposed to monochromatic green light. The fourth group of eggs was incubated under simultaneously changed temperature (according to the regime of the second group) and light (according to the regime of the third group) conditions. Tissue samples from the breast muscle ( M. pectoralis superficialis) were taken on embryonic days 9, 12, 15, 19 and 20, as well as on days 1, 3, 7, 14, 21 and 42 after hatching. Histological preparations were used to assess muscle cell diameter, connective tissue volume density, and the nucleocytoplasmic ratio of muscle cells. Our findings indicate that thermal and light manipulations during incubation increase diameter and decrease nucleocytoplasmic ratio in postnatal skeletal muscle cells. No differences were found among groups with regard to connective tissue volume density. These results can be explained by the influence of thermal and light manipulations during incubation on prolonged myoblast proliferation, as well as on the greater postnatal development of skeletal muscle cells.

Does the voltage‐gated calcium channel α2δ‐1 subunit play a dual function in skeletal muscle?

The dihydropyridine receptor (DHPR), a high voltage-activated calcium (Ca2+) channel, represents a key element in the excitation–contraction (EC) coupling machinery of muscle cells. In skeletal muscle, the DHPR fulfils two known functions: (i) it controls the ryanodine receptor activity, which makes it commonly referred to as the voltage-sensor for EC coupling and (ii) it supports an L-type voltage-activated Ca2+ current. The DHPR is a macromolecular complex composed of the Cav1.1 pore-forming subunit, surrounded by β1a, γ1 and α2δ-1 auxiliary subunits. Whereas knock-out animals have clearly demonstrated the essential role of Cav1.1 and β1a subunits in EC coupling and in the control of the Ca2+ conductance, the functional importance of α2δ-1 in skeletal muscle remains largely elusive, despite the lethal phenotype of α2δ-1-null embryos. Interestingly, down-regulation of the α2δ-1 protein in the BC3H1 muscle cell line with siRNA only resulted in acceleration of Ca2+ current activation kinetics with no effect on both EC coupling and Cav1.1 trafficking (Obermair et al. 2005). However, it is hard to understand how alteration of Ca2+ current kinetics could be the cause of the lethal phenotype observed in α2δ-1-null mice embryos; instead α2δ-1 is most likely to be involved in other cell functions independent of the DHPR activity. Previous observations suggested such a function: (i) α2δ-1 appears early during muscle development, at a period when the Cav1.1 subunit is not yet expressed, and (ii) sequence analysis of α2δ-1 revealed the presence of consensus domains, known to be involved in cell adhesion and protein–protein interactions (see Fig. 1 for structural organization of the α2δ-1 subunit). In a recent issue of The Journal of Physiology, Garcia et al. raised the possibility that α2δ-1 could mediate the interaction of muscle cells with the extracellular matrix (Garcia et al. 2008). Using immunohistochemistry and a siRNA knock-down strategy, the authors provided new insights into the functional involvement of α2δ-1 in skeletal muscle cells.

Differential expression analysis and regulatory network reconstruction for genes associated with muscle growth and adipose deposition in obese and lean pigs

During the growth and development of skeletal muscle cells and adipose cells, the regulatory mechanism of micro-effect polygenes determines porcine meat quality, carcass characteristics and other relative quantitative traits. Obese and lean type pig breeds show obvious differences in muscle growth and adipose deposition; however, the molecular mechanism underlying this phenotypic variation remains unknown. We used pathway-focused oligo microarray studies to examine the expression changes of 140 genes associated with muscle growth and adipose deposition in longissimus dorsi muscle at six growth stages (birth, 1, 2, 3, 4 and 5 months) of Landrace (a leaner, Western breed) and Taihu pigs (a fatty, indigenous, Chinese breed). Variance analysis (ANOVA) revealed that differences in the expression of 18 genes in Landrace pigs and three genes in Taihu pigs were very significant (FDR-adjusted permutation, P < 0.01) and differences for 22 genes in Landrace pigs and seven genes in Taihu pigs were significant (FDR-adjusted permutation, P < 0.05) among six growth stages. Clustering analysis revealed a high level of significance (FDR-adjusted, P < 0.01) for four gene expression patterns, in which genes that strongly up-regulated were mainly associated with the positive regulation of myofiber formation and fatty acid biogenesis and genes that strongly down-regulated were mainly associated with the inhibition of cell proliferation and positive regulation of fatty acid β-oxidation. Based on a dynamic Bayesian network (DBN) model, gene regulatory networks (GRNs) were reconstructed from time-series data for each pig breed. These two GRNs initially revealed the distinct differences in physiological and biochemical aspects of muscle growth and adipose deposition between the two pig breeds; from these results, some potential key genes could be identified. Quantitative real-time RT-PCR (QRT-PCR) was used to verify the microarray data for five modulated genes, and a good correlation between the two measures of expression was observed for both two pig breeds at different growth stages ( r = 0.876 ± 0.095). These results highlight some possible candidate genes for porcine meat quality and carcass traits and provide some data on which gene(s) should be further studied for elucidating the molecular mechanism of muscle growth and fat deposition.

Abnormal formation of sarcoplasmic reticulum networks and triads during early development of skeletal muscle cells in mitsugumin29-deficient mice.

Recently, we detected a novel membrane protein, mitsugumin29 (MG29), in the triads in rabbit skeletal muscle cells and suggested important roles for this membrane protein in the formation of the sarcoplasmic reticulum (SR) networks and triads in muscle cells. In the present study, we examined the development of skeletal muscle cells in MG29-deficient mice to try to determine the roles played by MG29 in the formation of the SR networks and triads. Ultrastructural observations revealed some morphological abnormalities in these mice, such as incomplete formation of the SR networks, an irregular running of the transverse tubule and a partial defect in the triads at the A-I junctional region. These ultrastructural abnormalities occurred during early myogenesis and were preserved until the adult stage. The possible roles for MG29 in the formation of SR networks and triads in skeletal muscle cells are discussed in the light of these observations.

Role of protein kinase C in 1,25(OH)2-vitamin D3 modulation of intracellular calcium during development of skeletal muscle cells in culture

Regulation of muscle cell Ca(2+) metabolism by 1, 25-dihydroxy-vitamin D(3) [1,25(OH)(2)D(3)] is mediated by the classic nuclear mechanism and a fast, nongenomic mode of action that activates signal transduction pathways. The role of individual protein kinase C (PKC) isoforms in the regulation of intracellular Ca(2+) levels ([Ca(2+)](i)) by the hormone was investigated in cultured proliferating (myoblasts) and differentiated (myotubes) chick skeletal muscle cells. 1,25(OH)(2)D(3) (10(-9) M) induced a rapid (30- to 60-s) and sustained (>5-min) increase in [Ca(2+)](i) which was markedly higher in myotubes than in myoblasts. The effect was suppressed by the PKC inhibitor calphostin C. In differentiated cells, PKC activity increased in the particulate fraction and decreased in cytosol to a greater extent than in proliferating cells after 5-min treatment with 1,25(OH)(2)D(3). By Western blot analysis, these changes were correlated to translocation of the PKC alpha isoform from cytosol to the particulate fraction, which was more pronounced in myotubes than in myoblasts. Specific inhibition of PKC alpha activity using antibodies against this isoform decreased the 1, 25(OH)(2)D(3)-induced [Ca(2+)](i) sustained response associated with Ca(2+) influx through voltage-dependent calcium channels. Neomycin, a phospholipase C (PLC) inhibitor, blocked its effects on [Ca(2+)](i), PKC activity, and translocation of PKC alpha. Exposure of myotubes to 1,2-dioleyl-rac-glycerol (1,2-diolein), also increased [Ca(2+)](i), PKC activity, and the amount of PKC alpha associated with the particulate fraction. Changes in [Ca(2+)](i) induced by diolein were inhibited by calphostin C and nifedipine. The results indicate that PKC alpha activation via PLC-catalyzed phosphoinositide hydrolysis is part of the mechanism by which 1, 25(OH)(2)D(3) regulates muscle intracellular Ca(2+) through modulation of the Ca(2+) influx pathway of the Ca(2+) response to the sterol.

Expression of the Sodium/Calcium Exchanger in Mammalian Skeletal Muscle Cells in Primary Culture

Previous investigations have demonstrated molecular and functional expression, at early phases of development of skeletal muscle cells in primary culture, of cardiac isoforms of proteins involved in calcium transport and regulation, like the L-type calcium channel. Here the expression of the cardiac isoform of the Na+/Ca2+ exchanger (NCX1) was studied in skeletal muscle cells developing in vitro, by using biochemical, immunological, and electrophysiological techniques. Northern and Western blot experiments revealed the presence of this cardiac exchanger and its increasing expression during the early phases of development. Confocal imaging of myotubes showed an NCX1 distribution that was predominantly sarcolemmal. The whole-cell patch-clamp technique allowed us to record ionic currents, the direction and the amplitude of which depended on extracellular sodium and calcium concentrations. The developmental changes of this functional expression could be correlated with the molecular NCX1 expression changes. Taken together these data demonstrate the presence of the NCX1 isoform of the Na+/Ca2+ exchanger during in vitro myogenesis and reinforce the theory that significant levels of cardiac-type proteins are transiently expressed during the early phases of the skeletal muscle cell development.