TY - JOUR
T1 - Dominant negative murine serum response factor
T2 - Alternative splicing within the activation domain inhibits transactivation of serum response factor binding targets
AU - Belaguli, Narasimhaswamy S.
AU - Zhou, Wei
AU - Trinh, Thuy Hanh T.
AU - Majesky, Mark W.
AU - Schwartz, Robert J.
PY - 1999/7
Y1 - 1999/7
N2 - Primary transcripts encoding the MADS box superfamily of proteins, such as MEF2 in animals and ZEMa in plants, are alternatively spliced, producing several isoformic species. We show here that murine serum response factor (SRF) primary RNA transcripts are alternatively spliced at the fifth exon, deleting approximately one-third of the C-terminal activation domain. Among the different muscle types examined, visceral smooth muscles have a very low ratio of SRFΔ5 to SRF. Increased levels of SRFΔ5 correlates well with reduced smooth muscle contractile gene activity within the elastic aortic arch, suggesting important biological roles for differential expression of SRFΔ5 variant relative to wild-type SRF. SRFΔ5 forms DNA binding-competent homodimers and heterodimers. SRFΔ5 acts as a naturally occurring dominant negative regulatory mutant that blocks SRF-dependent skeletal α-actin, cardiac α-actin, smooth α-actin, SM22α, and SRF promoter-luciferase reporter activities. Expression of SRFA5 interferes with differentiation of myogenic C2C12 cells and the appearance of skeletal α-actin and myogenin mRNAs. SRFΔ5 repressed the serum-induced activity of the c-fos serum response element. SRFΔ5 fused to the yeast Gal4 DNA binding domain displayed low transcriptional activity, which was complemented by overexpression of the coactivator ATF6. These results indicate that the absence of exon 5 might be bypassed through recruitment of transcription factors that interact with extra-exon 5 regions in the transcriptional activating domain. The novel alternatively spliced isoform of SRF, SRFΔ5, may play an important regulatory role in modulating SRF-dependent gene expression.
AB - Primary transcripts encoding the MADS box superfamily of proteins, such as MEF2 in animals and ZEMa in plants, are alternatively spliced, producing several isoformic species. We show here that murine serum response factor (SRF) primary RNA transcripts are alternatively spliced at the fifth exon, deleting approximately one-third of the C-terminal activation domain. Among the different muscle types examined, visceral smooth muscles have a very low ratio of SRFΔ5 to SRF. Increased levels of SRFΔ5 correlates well with reduced smooth muscle contractile gene activity within the elastic aortic arch, suggesting important biological roles for differential expression of SRFΔ5 variant relative to wild-type SRF. SRFΔ5 forms DNA binding-competent homodimers and heterodimers. SRFΔ5 acts as a naturally occurring dominant negative regulatory mutant that blocks SRF-dependent skeletal α-actin, cardiac α-actin, smooth α-actin, SM22α, and SRF promoter-luciferase reporter activities. Expression of SRFA5 interferes with differentiation of myogenic C2C12 cells and the appearance of skeletal α-actin and myogenin mRNAs. SRFΔ5 repressed the serum-induced activity of the c-fos serum response element. SRFΔ5 fused to the yeast Gal4 DNA binding domain displayed low transcriptional activity, which was complemented by overexpression of the coactivator ATF6. These results indicate that the absence of exon 5 might be bypassed through recruitment of transcription factors that interact with extra-exon 5 regions in the transcriptional activating domain. The novel alternatively spliced isoform of SRF, SRFΔ5, may play an important regulatory role in modulating SRF-dependent gene expression.
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U2 - 10.1128/MCB.19.7.4582
DO - 10.1128/MCB.19.7.4582
M3 - Article
C2 - 10373507
AN - SCOPUS:0033000331
SN - 0270-7306
VL - 19
SP - 4582
EP - 4591
JO - Molecular and cellular biology
JF - Molecular and cellular biology
IS - 7
ER -