1: Biochem Biophys Res Commun. 1999 Nov;265(1):222-32. 

Transcriptional activation of the myogenin gene by MEF2-mediated recruitment of
myf5 is inhibited by adenovirus E1A protein.

Johanson M, Meents H, Ragge K, Buchberger A, Arnold HH, Sandmoller A.

University of Uppsala, BMC, Husargatan 3, Uppsala, 75124, Sweden.

The basic helix-loop-helix (bHLH) transcription factor myogenin plays a crucial
role in terminal differentiation of committed myoblasts into mature myocytes.
Transcriptional activation of the myogenin gene requires coordinate action of
myocyte enhancer factor 2 (MEF2) proteins and the myogenic bHLH regulators, MyoD
or Myf5. Here we show that transcription of the myogenin gene in differentiated
cells correlates with MEF2 and NF1 binding to their cognate sites in the
proximal myogenin promoter but not with binding of Myf5 or MyoD to the E-box.
The importance of MEF2 activity was further demonstrated by expression of
antisense MEF2 RNA which repressed MEF2 and Myf5-mediated MEF2 site-dependent
reporter gene activation and the synergistic transactivation of a myogenin CAT
reporter by Myf5 and MEF2. Adenovirus E1A which has previously been shown to
specifically interfere with myogenin gene transcription also inhibited the
cooperative transactivation by Myf5/MEF2 and MEF2. Consistently,
coimmunoprecipitation studies revealed impaired MEF2/Myf5 protein-protein
interactions. These results support a model of transcriptional activation and
stabilization of myogenin expression in which DNA-bound MEF2 recruits myogenic
bHLH factors into an active but E1A-sensitive transcription factor complex.
Copyright 1999 Academic Press.

PMID: 10548518 [PubMed - indexed for MEDLINE]


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2: J Mol Biol. 1995 Oct 13;253(1):17-31. 

Myotube-specific activity of the human aldolase A M-promoter requires an
overlapping binding site for NF1 and MEF2 factors in addition to a binding site
(M1) for unknown proteins.

Salminen M, Spitz F, Fiszman MY, Demignon J, Kahn A, Daegelen D, Maire P.

Institut Cochin de Genetique Moleculaire, INSERM U129, Universite Rene
Descartes, Paris, France.

The human aldolase A gene is expressed in several tissues through the use of
three alternative promoters. The activity of one of the promoters, pM, is
restricted to skeletal muscle. We reported previously that a proximal 280 bp pM
fragment confers tissue-specific expression to a CAT reporter gene in transgenic
mice. This small regulatory region directs expression to muscle composed mainly
of fast-twitch fibers. Here we show that a minimal promoter fragment from
base-pairs -164 to +45 is sufficient to highly active pM during myoblast
differentiation in cell culture and demonstrate that two DNA elements play a
major role in this activation. These elements consist of a binding site (M1) for
unknown ubiquitous proteins and an overlapping binding site for MEF2 and NF1
families of transcription factors. The NF1 factor constitute the main binding
activity on the MEF2/NF1 site and, interestingly, some of the DNA-protein
complexes that form with muscle nuclear extracts on the NF1 element differ from
those that form with non-muscular extracts.

PMID: 7473711 [PubMed - indexed for MEDLINE]


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