Transcriptional Regulation of the Chicken Caldesmon Gene
ACTIVATION OF GIZZARD-TYPE CALDESMON PROMOTER REQUIRES A CArG BOX-LIKE MOTIF (*)
- From the Department of Neurochemistry and Neuropharmacology, Biomedical Research Center, Osaka University Medical School, 2-2 Yamadaoka, Suita, Osaka 565, Japan
- § To whom all correspondence should be addressed. Tel.: 81-6-879-3680; Fax: 81-6-879-3689.
Abstract
Caldesmon, which plays a vital role in the actomyosin system, is distributed in smooth muscle and non-muscle cells, and its
isoformal interconversion between a high M
form and low M
form is a favorable molecular event for studying phenotypic modulation of smooth muscle cells. Genomic analysis reveals two
promoters, of which the gizzard-type promoter displays much higher activity than the brain-type promoter. Here, we have characterized
transcriptional regulation of the gizzard-type promoter. Transient transfection assays in chick gizzard smooth muscle cells,
chick embryo fibroblasts, mouse skeletal muscle cell line (C2C12), and HeLa cells revealed that the promoter activity was
high in smooth muscle cells and fibroblasts, but was extremely low in other cells. Cell type-specific promoter activity depended
on an element, CArG1, containing a unique CArG box-like motif (CCAAAAAAGG) at −315, while multiple E boxes were not directly
involved in this event. Gel shift assays showed the specific interaction between the CArG1 and nuclear protein factors in
smooth muscle cells and fibroblasts. These results suggest that the CArG1 is an essential cis-element for cell type-specific expression of caldesmon and that the function of CArG1 might be controlled under phenotypic
modulation of smooth muscle cells.
Footnotes
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↵* This research was supported in part by grants-in-aid for scientific research from the Ministry of Education, Science and Culture of Japan. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵1 The abbreviations used are:
- SMC
-
smooth muscle cell
- SM
-
smooth muscle
- CaD
-
caldesmon
- l- and h-CaD
-
low and high M
CaD
- CEF
-
chick embryo fibroblasts
- CAT
-
chloramphenicol acetyltransferase
- DMEM
-
Dulbecco's modified Eagle's medium
- RSV
-
Rous sarcoma virus.
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↵2 K. Hayashi, T. Momiyama, and K. Sobue, manuscript in preparation.
-
- Received March 2, 1995.
- Revision received May 22, 1995.
- © 1995 by The American Society for Biochemistry and Molecular Biology, Inc.
