Myoblast are a type of stem cells that exist in muscles. Skeletal muscle cells are called muscle fibers and are made when myoblasts fuse together; muscle fibers therefore have multiple nuclei. Myoblasts that do not form muscle fibers differentiate into satellite cells. These satellite cells remain adjacent to a muscle fiber, separated only by its cell membrane and by the endomycium (the connective tissue of collagen surrounding the muscle fiber).

Acetylcholinesterase (AChE)

• Membrane-bound AChE can thus serve as an early differentiation marker for embryonic chick myoblasts in mixed primary cultures. PMID: 1472543

ADAM12

• In C2C12 cells, ADAM12 is expressed at low levels in undifferentiated myoblasts and is transiently up-regulated at the onset of differentiation when myoblasts fuse into multinucleated myotubes, whereas other ADAMs, such as ADAMs 9, 10, 15, 17, and 19, are expressed at all stages of differentiation. PMID: 10788519

alpha- and beta-tropomyosin (pT)

• normally concentrated in myotubes. PMID: 6301863

beta-Enolase

• a marker of human myoblast heterogeneity prior to differentiation. PMID: 1339335
• expressed in proliferating adult myoblasts as well as in differentiated myotubes. PMID: 7852315

CD56

• a common antigen shared by NK cells and muscle fibers during certain stages of muscle maturation, regeneration, or denervation. When expressed in the muscle, CD56 may facilitate the adhesion of cytotoxic lymphocytes to the muscle and play a role in muscle fiber injury. PMID: 1371910
• Immunohistochemistry and flow cytometry for the identification of the myoblasts was carried out. The results were obtained through flow cytometry, using CD56 as an indicator of the presence of myoblasts. PMID: 15909099
• The present study describes the application of a new technique for the isolation of adult human myoblasts and putative muscle-derived stem cells (MDSCs), based on microbead-immunomagnetic selection of CD56+ cells, derived from craniofacial skeletal muscle. PMID: 15270704

Desmin

• a muscle-specific intermediate filament protein, is upregulated during skeletal myogenesis. PMID: 11396722
• one of the earliest myogenic markers and play a key role in this myogenesis. PMID: 8120103  
• a muscle-specific structural protein and one of the earliest known muscle-specific genes to be expressed during cardiac and skeletal muscle development, and stably and firmly connected to the outer nuclear surface in skeletal muscles cells in vivo and in vitro. PMID: 16160856
• desmin-positive, myosin-negative myoblasts are proliferating cells, and we conclude that the progeny of adult myoblasts exhibit more desmin-expressing cells of this type than embryonic myoblasts do. PMID: 2292359

Fluoro-Gold (FG)

• as a vital stain to label the nuclei of donor myoblasts in myoblast transfer studies. PMID: 2036600

Lactate Dehydrogenase (LDH)

• marker of myogenesis. PMID: 9635277
• myoblasts incubated 24 hours in the presence of 1 mM divicine, showed an increase of a significant release of iron and lactate dehydrogenase in the culture medium. PMID: 10794072

M-Cadherin (muscle cadherin)

• a calcium-dependent intercellular adhesion molecule, is expressed in skeletal muscle cells, and important for skeletal muscle development, in particular the fusion of myoblasts into myotubes. PMID: 9841904
• expressed in mammalian skeletal myoblasts, and plays an important role in skeletal myogenesis. PMID: 7994077

M-Calpain

• present at the onset of myoblast fusion and throughout this phenomenon and involved in myoblast fusion via desmin cleavage. PMID: 8785519
• the muscular dysgenesis mouse provides a relevant model to study myoblast fusion and that m-calpain is involved in this process. PMID: 10949052
• involved in myoblast fusion by cleaving certain proteins identified here. This cleavage could modify membrane and cytoskeleton organization for the myoblasts to fuse. PMID: 9925759
• m-calpain and calpastatin are functionally involved in myoblast fusion. PMID: 9587056, PMID: 9299163, PMID: 7813519

M-CAM (melanoma cell adhesion molecule)

• expressed on activated myoblasts, both in vitro and in vivo. These studies identify M-CAM as a novel marker for myogenic progenitors in human fetal muscle and confirm that downregulation of this protein promotes myoblast fusion. PMID: 16835268

MRF4 (myogenic/muscle regulating factor-4)

• the myoblast differentiation factor, is expressed in skeletal muscles. PMID: 16007210
• the myogenic regulatory factors, play a key role in skeletal muscle formation. PMID: 15110722
• MRF4 mRNAs were detected in satellite cell-derived myoblasts in the first stages of muscle regeneration analyzed (2--3 days P-I). PMID: 11410613

Myf-5 (muscle regulatory factor-5)

• Myf5 mRNAs were detected in satellite cell-derived myoblasts in the first stages of muscle regeneration analyzed (2--3 days P-I). PMID: 11410613
• the earliest-known muscle-specific factor to be expressed in vivo and its expression is associated with determination of the myoblast lineage. PMID: 9425159
• involved in the establishment of skeletal muscle precursor cells. PMID: 9427286

MyoD

• MyoD mRNAs were detected in satellite cell-derived myoblasts in the first stages of muscle regeneration analyzed (2--3 days P-I). PMID: 11410613
• MyoD controls myotube formation by regulating the expression of alpha4, alpha5, and alpha7 integrins. PMID: 16179075
• belong to the family of basic helix-loop-helix transcription factors that are key operators in skeletal muscle differentiation. PMID: 9658178

Myogenin

• an important regulator of skeletal muscle cell differentiation, and the expression of myogenin is under the control of FGF. PMID: 1690720
• one of the regulatory genes involved in the regulation of differentiation to myofibers after treatment with 3-deazaadenosine, a metabolic inhibitor of methyl transfer reactions. PMID: 8853901
• myogenin is not only required for early steps during differentiation but also maturation steps of myotubes. PMID: 9669033
• fetal myoblasts express both MyoD and myogenin within the first day in culture and rapidly transit into the differentiated myosin-expressing state. In contrast, adult myoblasts are essentially negative for MyoD and myogenin by culture Day 1 and subsequently express first MyoD and then myogenin before expressing sarcomeric myosin. PMID: 11259448

Myosin

• in the rat, each myoblast population expresses a unique pattern of myosin heavy chains (MyHCs) during differentiation in vitro. PMID: 9056645
• majority of fetal myocytes (differentiated myoblasts) and myotubes coexpressed ventricular and embryonic myosin heavy chains in culture. PMID: 1936563

nls beta-Galactosidase

• a marker for studying myogenic lineage or the efficacy of myoblast transfer. PMID: 9143666

N-Cadherin (neural cadherin)

• expressed in mammalian skeletal myoblasts. PMID: 7994077

p21

• transient p21 gene silencing represent a basis for viral vector-mediated drug-inducible p21 shRNA expression in Dys(-) myoblasts which might enhance, prolong and regulate the proliferation effect. PMID: 15536518

Phosphoprotein (pp(65;4.5))

• normally concentrated in presumptive myoblasts (PMbs). PMID: 6301863

Pax3

• an evolutionarily conserved transcription factor expressed in the lateral dermomyotome, a region that gives rise to limb muscle progenitors. Pax3 may suppress the terminal differentiation of migrating limb myoblasts and that the PAX3-forkhead fusion may contribute to the phenotype of alveolar rhabdomyosarcoma by preventing terminal differentiation. PMID: 7744814
• differentially regulated within the somite in both spatial and temporal domains. Hypaxial muscle Cre mice will allow for specific manipulation of gene expression in this subset of developing skeletal muscle. PMID: 15789408
• a premyoblast marker. PMID: 12361602

Pax7

• a specific marker of satellite cells. PMID: 15469979, PMID: 16608873
• play key roles in muscle cell development and differentiation. PMID: 16157701
• Anti-Pax7 reactivity was found in the majority of satellite cells but a small population was Pax7 negative. Neither could we identify Pax7-positive nuclei in freshly regenerating myotubes or in presumed myoblasts in these biopsies. Similarly, in myogenic cell cultures derived from the explantation of human foetal muscle Pax7 expression was low or undetectable at the proliferative myoblast stage but it became prominent in an increasing proportion of mononucleate cells after the induction of differentiation. Despite this, in the biopsy samples, we occasionally found Pax7-positive nuclei in muscle fibres that seemed to be undergoing degenerative changes. Most of these were found to be the nuclei of cells engaged in focal regenerative processes, but Pax7 re-expression by myonuclei "in distress" cannot be ruled out entirely. PMID: 14648195
• a member of mouse Pax gene family. It was expressed from day 8 to 17 p. c. during murine embryogenesis, mainly restricted to the central nerve systems. Additional Pax7 expression could be followed during myogenesis from the dermamyotome of the somites to the skeletal muscle tissues. For the first time, we demonstrated that Pax7 is expressed in mouse myoblast cell line, C2C12. PMID: 9387795

PK-K (K-isozyme of pyruvate kinase)

• normally concentrated in presumptive myoblasts (PMbs). PMID: 6301863

PK-M (M-isozyme of pyruvate kinase)

• normally concentrated in myotubes. PMID: 6301863

Tbx3

• a member of the T-box family of transcription factors, can efficiently blocks myogenic differentiation of C2C12 myoblasts. PMID: 12032820

Titin

• linked during myofibrillogenesis in postmitotic mononucleated myoblasts. PMID: 3536962