The four members of the MEF2 family of MADS-box transcription factors, MEF2-A, MEF2-B, MEF2-C and MEF2-D, are expressed in overlapping patterns in developing muscle and neural cell lineages during embryogenesis. However, during late fetal development and postnatally, MEF2 transcripts are also expressed in a wide range of cell types. Because MEF2 expression is controlled by translational and post-translational mechanisms, it has been unclear whether the presence of MEF2 transcripts in the embryo reflects transcriptionally active MEF2 proteins. To define the temporospatial expression pattern of transcriptionally active MEF2 proteins during mouse embryogenesis, we generated transgenic mice harboring a lacZ reporter gene controlled by three tandem copies of the MEF2 site and flanking sequences from the desmin enhancer, which is active in cardiac, skeletal and smooth muscle cells. Expression of this MEF2-dependent transgene paralleled expression of MEF2 mRNAs in developing myogenic lineages and regions of the adult brain. However, it was not expressed in other cell types that express MEF2 transcripts. Tandem copies of the MEF2 site from the c-jun promoter directed expression in a similar pattern to the desmin MEF2 site, suggesting that transgene expression reflects the presence of transcriptionally active MEF2 proteins, rather than other factors specific for DNA sequences flanking the MEF2 site. These results demonstrate the presence of transcriptionally active MEF2 proteins in the early muscle and neural cell lineages during embryogenesis and argue against the existence of lineage-restricted MEF2 cofactors that discriminate between MEF2 sites with different immediate flanking sequences. The discordance between MEF2 mRNA expression and MEF2 transcriptional activity in nonmuscle cell types of embryos and adults also supports the notion that post-transcriptional mechanisms regulate the expression of MEF2 proteins.

Reference

Amacher
S. L.
,
Buskin
J. N.
,
Hauschka
S. D.
(
1993
)
Multiple regulatory elements contribute differentially to muscle creatine kinase enhancer activity in skeletal and cardiac muscle.
Mol. Cell. Biol
13
,
2753
2764
Andres
V.
,
Cervera
M.
,
Mahdavi
V.
(
1995
)
Determination of the consensus binding site for MEF2 expressed in muscle and brain reveals tissue-specific sequence constraints.
J. Biol. Chem
270
,
23246
23249
Black
B. L.
,
Martin
J. F.
,
Olson
E. N.
(
1995
)
The mouse MRF4 promoter is transactivated directly and indirectly by muscle specific transcription factors.
J. Biol. Chem
270
,
2889
2892
Black
B. L.
,
Ligon
K. L.
,
Zhang
Y.
,
Olson
E. N.
(
1996
)
Cooperative transcriptional activation by the neurogenic basic helix-loop-helix protein MASH1 and members of the myocyte enhancer factor-2 (MEF2) family.
J. Biol. Chem
271
,
26659
26663
Black
B. L.
,
Lu
J.
,
Olson
E. N.
(
1997
)
The MEF2A 3untranslated region functions as a cis-acting translational repressor.
Mol. Cell. Biol
17
,
2756
2763
Black
B. L.
,
Olson
E. N.
(
1998
)
Transcriptional control of muscle development by myocyte enhancer factor-2 (MEF2) proteins.
Annu. Rev. Cell Dev. Biol
14
,
167
196
Braun
T.
,
Bober
E.
,
Rudnicki
M. A.
,
Jaenisch
R.
,
Arnold
H. H.
(
1994
)
MyoD expression marks the onset of skeletal myogenesis in Myf-5 mutant mice.
Development
120
,
3083
3092
Breitbart
R. E.
,
Liang
C.
,
Smoot
L. B.
,
Laheru
D. A.
,
Mahdavi
V.
,
Nadal-Ginard
B.
(
1993
)
A fourth human MEF2 transcription factor, hMEF2D, is an early marker of the myogenic lineage.
Development
118
,
1095
1106
Chambers
A. E.
,
Kotecha
S.
,
Towers
N.
,
Mohun
T. J.
(
1992
)
Muscle-specific expression of SRF-related genes in the early embryo of Xenopus laevis.
EMBO J
11
,
4981
4991
Cheng
T.-C.
,
Hanley
T. A.
,
Mudd
J.
,
Merlie
J. P.
,
Olson
E. N.
(
1992
)
Mapping of myogenin transcription during embryogenesis using transgenes linked to the myogenin control region.
J. Cell Biol
119
,
1649
1656
Cheng
T.-C.
,
Wallace
M.
,
Merlie
J. P.
,
Olson
E. N.
(
1993
)
Separable regulatory elements govern myogenin transcription in embryonic somites and limb buds.
Science
261
,
215
218
Cserjesi
P.
,
Olson
E. N.
(
1991
)
Myogenin induces muscle-specific enhancer factor MEF-2 independently of other muscle-specific gene products.
Mol. Cell. Biol
11
,
4854
4862
Dalton
S.
,
Treisman
R.
(
1992
)
Characterization of SAP-1, a protein recruited by serum response factor to the c-fos serum response element.
Cell
68
,
597
612
Dodou
E.
,
Sparrow
D. B.
,
Mohun
T.
,
Treisman
R.
(
1995
)
MEF2 proteins, including MEF2A, are expressed in both muscle and non-muscle cells.
Nucleic Acids Res
23
,
4267
4274
Edmondson
D. G.
,
Lyons
G. E.
,
Martin
J. F.
,
Olson
E. N.
(
1994
)
Mef2 gene expression marks the cardiac and skeletal muscle lineages during mouse embryogenesis.
Development
120
,
1251
1263
Gossett
L. A.
,
Kelvin
D. J.
,
Sternberg
E. A.
,
Olson
E. N.
(
1989
)
A new myocyte-specific enhancer-binding factor that recognizes a conserved element associated with multiple muscle-specific genes.
Mol. Cell. Biol
9
,
5022
5033
Grueneberg
D.
,
Natesan
S.
,
Alexandre
C.
,
Gilman
M. Z.
(
1992
)
Human and Drosophila homeodomain proteins that enhance the DNA-binding activity of serum response factor.
Science
257
,
1089
1095
Han
J.
,
Jiang
Y.
,
Li
Z.
,
Kravchenko
V. V.
,
Ulevitch
R. J.
(
1997
)
Activation of the transcription factor MEF2C by the MAP kinase p38 in inflammation.
Nature
386
,
296
299
Han
T. H.
,
Lamph
W. W.
,
Prywes
R.
(
1992
)
Mapping of epidermal growth factor-, serum-, and phorbol ester-responsive sequence elements in the c-jun promoter.
Mol. Cell. Biol
12
,
4472
4477
Han
T. H.
,
Prywes
R.
(
1995
)
Regulatory role of MEF2D in serum induction of the c-jun promoter.
Mol. Cell. Biol
15
,
2907
2915
Herzog
A.
,
Brosamle
C.
(
1997
)
Semi free-floating treatment: a simple and fast method to process consecutive sections for immunohistochemistry and neuronal tracing.
J. Neuroscience Methods
72
,
57
61
Kato
Y.
,
Kravchenko
V. V.
,
Tapping
R. I.
,
Han
J.
,
Ulevitch
R. J.
,
Lee
J. D.
(
1997
)
BMK1/ERK5 regulates serum-induced early gene expression through transcription factor MEF2C.
EMBO J
16
,
7054
7066
Kaushal
S.
,
Schneider
J. W.
,
Nadal-Ginard
B.
,
Mahdavi
V.
(
1994
)
Activation of the myogenic lineage by MEF2A, a factor that induces and cooperates with MyoD.
Science
266
,
1236
1240
Kothary
R.
,
Clapoff
S.
,
Darling
S.
,
Perry
M. D.
,
Moran
L. A.
,
Rossant
J.
(
1989
)
Inducible expression of an hsp68-lacZ hybrid gene in transgenic mice.
Development
105
,
707
714
Krainc
D.
,
Bai
G.
,
Okamoto
S.
,
Carles
M.
,
Kusiak
J. W.
,
Brent
R. N.
,
Lipton
S. A.
(
1998
)
Synergistic activation of the N-methyl-d-aspartate receptor subunit 1 promoter by myocyte enhancer factor 2C and Sp1.
J. Biol. Chem
273
,
26218
26224
Kuisk
I. R.
,
Li
H.
,
Tran
D.
,
Capetanaki
Y.
(
1996
)
A single MEF2 site governs desmin transcription in both heart and skeletal muscle during mouse embryogenesis.
Dev. Biol
174
,
1
13
Lee
K. J.
,
Hickey
R.
,
Zhu
H.
,
Chien
K. R.
(
1994
)
Positive regulatoryelements (HF-1a and HF-1b) and a novel negative regulatory element (HF-3) mediate ventricular muscle-specific expression of myosin light-chain 2-luciferase fusion genes in transgenic mice.
Mol. Cell. Biol
14
,
1220
1229
Leifer
D.
,
Krainc
D.
,
Yu
Y.-T.
,
McDermott
J. C.
,
Breitbart
R. E.
,
Heng
J.
,
Neve
R. L.
,
Kosofsky
B.
,
Nadal-Ginard
B.
,
Lipton
S. A.
(
1993
)
MEF2C, a MADS/MEF2-family transcription factor expressed in a laminar distribution in cerebral cortex.
Proc. Natl. Acad. Sci. USA
90
,
1546
1550
Li
H.
,
Capetanaki
Y.
(
1994
)
An E box in the desmin promoter cooperates with the E box and MEF-2 sites of a distal enhancer to direct muscle-specific transcriptions.
EMBO J
13
,
3580
3589
Liu
S.
,
Liu
P.
,
Borras
A.
,
Chatila
T.
,
Speck
S. H.
(
1997
)
Cyclosporin A-sensitive induction of the Epstein-Barr virus lytic switch is mediated via a novel pathway involving a MEF2 family member.
EMBO J
16
,
143
153
Lin
Q.
,
Schwarz
J.
,
Bucana
C.
,
Olson
E. N.
(
1997
)
Control of cardiac morphogenesis and myogenesis by transcription factor MEF2C.
Science
276
,
1404
1407
Lin
Q.
,
Lu
J.
,
Yanagisawa
H.
,
Webb
R.
,
Lyons
G. E.
,
Richardson
J. A.
,
Olson
E. N.
(
1998
)
Requirement of the MADS box transcription factor MEF2C for vascular development.
Development
125
,
4565
4574
Lin
X.
,
Shah
S.
,
Bulleit
R. F.
(
1996
)
The expression of MEF2 genes is implicated in CNS neuronal differentiation.
Brain Res. Mol. Brain Res
42
,
307
316
Lyons
G. E.
,
Micales
B. K.
,
Schwarz
J.
,
Martin
J. F.
,
Olson
E. N.
(
1995
)
Expression of mef2 genes in the mouse central nervous system suggests a role in neuronal maturation.
J. Neurosci
15
,
5727
5728
Mao
Z.
,
Nadal-Ginard
B.
(
1996
)
Functional and physical interactions between mammalian achaete-scute homolog 1 and myocyte enhancer factor 2A.
J. Biol. Chem
271
,
14371
14375
Martin
J. F.
,
Schwarz
J. J.
,
Olson
E. N.
(
1993
)
Myocyte enhancer factor (MEF) 2C: A tissue-restricted member of the MEF-2 family of transcription factors.
Proc. Natl. Acad. Sci. USA
90
,
5282
5286
Martin
J. F.
,
Miano
J. M.
,
Hustad
C. M.
,
Copeland
N. G.
,
Jenkins
N. A.
,
Olson
E. N.
(
1994
)
A Mef2 gene that generates a muscle-specific isoform via alternative mRNA splicing.
Mol. Cell. Biol
14
,
1647
1656
McDermott
J. C.
,
Cardoso
M. C.
,
Yu
Y.-T.
,
Andres
V.
,
Leifer
D.
,
Krainc
D.
,
Lipton
S. A.
,
Nadal-Ginard
B.
(
1993
)
hMEF2C gene encodes skeletal muscle-and brain-specific transcription factors.
Mol. Cell. Biol
13
,
2564
2577
Molkentin
J. D.
,
Li
L.
,
Olson
E. N.
(
1996
)
Phosphorylation of the MADS-box transcription factor MEF2C enhances its DNA binding activity.
J. Biol. Chem
271
,
17199
17204
Naidu
P. S.
,
Ludolph
D. C.
,
To
R. Q.
,
Hinterberger
T. J.
,
Konieczny
S. F.
(
1995
)
Myogenin and MEF2 function synergistically to activate the MRF4 promoter during myogenesis.
Mol. Cell. Biol
15
,
2707
2718
Navankasattusas
S.
,
Zhu
H.
,
Garcia
A. V.
,
Evans
S. M.
,
Chien
K. R.
(
1992
)
A ubiquitous factor (HF-1a) and a distinct muscle factor (HF-1b/MEF2) form an E-box independent pathway for cardiac muscle gene expression.
Mol. Cell. Biol
12
,
1469
1479
Navankasattusas
S.
,
Sawadogo
M.
,
vanBilsen
M.
,
Dang
C. V.
,
Chien
K. R.
(
1994
)
The helix-loop-helix protein upstream stimulating factor regulates the cardiac ventricular myosin light-chain 2 gene via independent cis regulatory elements.
Mol. Cell. Biol
14
,
7331
7339
Pollock
R.
,
Treisman
R.
(
1991
)
Human SRF-related proteins: DNA-binding properties and potential regulatory targets.
Genes Dev
5
,
2327
2341
Ross
R. S.
,
Navankasatussas
S.
,
Harvey
R. P.
,
Chien
K. R.
(
1996
)
An HF-1a/HF-1b/MEF-2 combinatorial element confers cardiac ventricular specificity and establishes an anterior-posterior gradient of expression.
Development
122
,
1799
1809
Subramanian
S. V.
,
Nadal-Ginard
B.
(
1996
)
Early expression of the different isoforms of the myocyte enhancer factor-2 (MEF2) protein in myogenic as well as non-myogenic cell lineages during mouse embryogenesis.
Mech Dev
57
,
103
112
Woronicz
J. D.
,
Lina
A.
,
Calnan
B. J.
,
Szychowski
S.
,
Cheng
L.
,
Winoto
A.
(
1995
)
Regulation of Nur77 orphan steroid receptor in activation-induced apoptosis.
Mol. Cell. Biol
15
,
6364
6376
Yaworsky
P. J.
,
Gardner
D. P.
,
Klappen
C.
(
1997
)
Transgenic analyses reveal developmentally regulated neuron-and muscle-specific elements in the murine neurofilament light chain gene promoter.
J. Biol. Chem
272
,
25112
25120
Yee
S. P.
,
Rigby
P. W.
(
1993
)
The regulation of myogenin gene expression during the embryonic development of the mouse.
Genes Dev
7
,
1277
1289
Yu
Y.-T.
,
Breitbart
R. E.
,
Smoot
L. B.
,
Lee
Y.
,
Mahdavi
V.
,
Nadal-Ginard
B.
(
1992
)
Human myocyte-specific enhancer factor 2 comprises a group of tissue-restricted MADS box transcription factors.
Genes Dev
6
,
1783
1798
Zhao
M.
,
New
L.
,
Kravchenko
V. V.
,
Kato
Y.
,
Gram
H. M.
,
Padova
F. D.
,
Olson
E. N.
,
Ulevitch
R. J.
,
Han
J.
(
1999
)
Regulation of theMEF2 family of transcription factors by p38.
Mol. Cell. Biol
19
,
21
30
Zhu
H.
,
Nguyen
V. T. B.
,
Brown
A. B.
,
Pourhossieni
A.
,
Garcia
A. V.
,
van Bilsen
M.
,
Chien
K. R.
(
1993
)
A novel, tissue-restricted zinc finger protein (HF-1b) binds to the cardiac regulatory element (HF-1b/MEF2) within the rat myosin light chain-2 gene.
Mol. Cell. Biol
13
,
4432
4444
This content is only available via PDF.