Determination versus differentiation and the MyoD family of transcription factors

1995 ◽  
Vol 73 (9-10) ◽  
pp. 723-732 ◽  
Author(s):  
Lynn A. Megeney ◽  
Michael A. Rudnicki
Keyword(s):  
Skeletal Muscle ◽  
Transcription Factors ◽  
Sequence Homology ◽  
Expression Patterns ◽  
Myogenic Regulatory Factors ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix

The myogenic regulatory factors (MRFs) form a family of basic helix–loop–helix transcription factors consisting of Myf-5, MyoD, myogenin, and MRF4. The MRFs play key regulatory roles in the development of skeletal muscle during embryogenesis. Sequence homology, expression patterns, and genetargeting experiments have revealed a two-tiered subclassification within the MRF family. Myf-5 and MyoD are more homologous to one another than to the others, are expressed in myoblasts before differentiation, and are required for the determination or survival of muscle progenitor cells. By contrast, myogenin and MRF4 are more homologous to one another than to the others and are expressed upon differentiation, and myogenin is required in vivo as a differentiation factor while the role of MRF4 remains unclear. On this basis, MyoD and Myf-5 are classified as primary MRFs, as they are required for the determination of myoblasts, and myogenin and MRF4 are classified as secondary MRFs, as they likely function during terminal differentiation.Key words: MyoD, Myf-5, myogenin, MRF4, skeletal muscle.

scholarly journals An Examination of the Role of Transcriptional and Posttranscriptional Regulation in Rhabdomyosarcoma

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Alexander J. Hron ◽  
Atsushi Asakura
Keyword(s):  
Skeletal Muscle ◽  
Soft Tissue ◽  
Posttranscriptional Regulation ◽  
Progenitor Cell ◽  
Treatment Options ◽  
Soft Tissue Tumors ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Bhlh Proteins

Rhabdomyosarcoma (RMS) is an aggressive family of soft tissue tumors that most commonly manifests in children. RMS variants express several skeletal muscle markers, suggesting myogenic stem or progenitor cell origin of RMS. In this review, the roles of both recently identified and well-established microRNAs in RMS are discussed and summarized in a succinct, tabulated format. Additionally, the subtypes of RMS are reviewed along with the involvement of basic helix-loop-helix (bHLH) proteins, Pax proteins, and microRNAs in normal and pathologic myogenesis. Finally, the current and potential future treatment options for RMS are outlined.

scholarly journals SCL Assembles a Multifactorial Complex That Determines Glycophorin A Expression

2004 ◽  
Vol 24 (4) ◽  
pp. 1439-1452 ◽  
Author(s):  
Rachid Lahlil ◽  
Eric Lécuyer ◽  
Sabine Herblot ◽  
Trang Hoang
Keyword(s):  
Transcription Factors ◽  
Hematopoietic Cells ◽  
Inhibitory Effect ◽  
Erythroid Cell ◽  
Glycophorin A ◽  
Protein Activity ◽  
Protein Levels ◽  
Helix Loop Helix

ABSTRACT SCL/TAL1 is a hematopoietic-specific transcription factor of the basic helix-loop-helix (bHLH) family that is essential for erythropoiesis. Here we identify the erythroid cell-specific glycophorin A gene (GPA) as a target of SCL in primary hematopoietic cells and show that SCL occupies the GPA locus in vivo. GPA promoter activation is dependent on the assembly of a multifactorial complex containing SCL as well as ubiquitous (E47, Sp1, and Ldb1) and tissue-specific (LMO2 and GATA-1) transcription factors. In addition, our observations suggest functional specialization within this complex, as SCL provides its HLH protein interaction motif, GATA-1 exerts a DNA-tethering function through its binding to a critical GATA element in the GPA promoter, and E47 requires its N-terminal moiety (most likely entailing a transactivation function). Finally, endogenous GPA expression is disrupted in hematopoietic cells through the dominant-inhibitory effect of a truncated form of E47 (E47-bHLH) on E-protein activity or of FOG (Friend of GATA) on GATA activity or when LMO2 or Ldb-1 protein levels are decreased. Together, these observations reveal the functional complementarities of transcription factors within the SCL complex and the essential role of SCL as a nucleation factor within a higher-order complex required to activate gene GPA expression.

The Mef2c gene is a direct transcriptional target of myogenic bHLH and MEF2 proteins during skeletal muscle development

Development ◽  
2001 ◽  
Vol 128 (22) ◽  
pp. 4623-4633 ◽  
Author(s):  
Da-Zhi Wang ◽  
M. Renee Valdez ◽  
John McAnally ◽  
James Richardson ◽  
Eric N. Olson
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Transcription Factors ◽  
Binding Site ◽  
Control Region ◽  
Muscle Development ◽  
Regulatory Elements ◽  
Skeletal Muscle Development ◽  
Helix Loop Helix

Members of the MEF2 family of transcription factors are upregulated during skeletal muscle differentiation and cooperate with the MyoD family of myogenic basic helix-loop-helix (bHLH) transcription factors to control the expression of muscle-specific genes. To determine the mechanisms that regulate MEF2 gene expression during skeletal muscle development, we analyzed the mouse Mef2c gene for cis-regulatory elements that direct expression in the skeletal muscle lineage in vivo. We describe a skeletal muscle-specific control region for Mef2c that is sufficient to direct lacZ reporter gene expression in a pattern that recapitulates that of the endogenous Mef2c gene in skeletal muscle during pre- and postnatal development. This control region is a direct target for the binding of myogenic bHLH and MEF2 proteins. Mutagenesis of the Mef2c control region shows that a binding site for myogenic bHLH proteins is essential for expression at all stages of skeletal muscle development, whereas an adjacent MEF2 binding site is required for maintenance but not for initiation of Mef2c transcription. Our findings reveal the existence of a regulatory circuit between these two classes of transcription factors that induces, amplifies and maintains their expression during skeletal muscle development.

Regulation of neurogenesis by interactions between HEN1 and neuronal LMO proteins

Development ◽  
2000 ◽  
Vol 127 (2) ◽  
pp. 425-435 ◽  
Author(s):  
J. Bao ◽  
D.A. Talmage ◽  
L.W. Role ◽  
J. Gautier
Keyword(s):  
Neuronal Differentiation ◽  
Transcriptional Activity ◽  
Expression Patterns ◽  
Dorsal Side ◽  
Neural Plate ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Human Genes ◽  
Early Neurogenesis

Basic-helix-loop-helix transcription factors regulate neurogenesis and neuronal differentiation by as yet unknown mechanisms. We show that an embryonic neuronal-specific basic-helix-loop-helix protein, HEN1 (also known as NSCL1 or NHLH), interacts with ‘LIM only’ proteins. Examination of the expression patterns of XHEN1 and XLMO-3, the Xenopus homologues of these human genes, reveals extensive overlap during early neurogenesis: at the onset of gastrulation on the dorsal side of the blastopore lip and, subsequently, in the prospective neural plate. Binding of XLMO-3 increases the transcriptional activity of XHEN1 in vivo. Co-expression of these two genes in Xenopus embryos induces a cascade of expression of neuronal-specific basic-helix-loop-helix proteins that leads to neuronal differentiation. We propose that XHEN1, in concert with XLMO-3, is a critical regulator of neurogenesis.

Sign in / Sign up

Export Citation Format

Share Document