Expression of the Smooth Muscle Cell Calponin Gene Marks the Early Cardiac and Smooth Muscle Cell Lineages during Mouse Embryogenesis

doi:10.1074/jbc.271.12.7095

Expression of the Smooth Muscle Cell Calponin Gene Marks the Early Cardiac and Smooth Muscle Cell Lineages during Mouse Embryogenesis (*)

From the Department of Biochemistry and Molecular Biology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030

^§ Supported by a National Research Service Award. Sequence analysis was supported through National Cancer Institute Grant CA-16672 to the Dept. of Biomathematics. To whom correspondence and reprint requests should be addressed:
Dept. of Physiology, Cardiovascular Research Center, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226
. Tel: 414-456-5716; Fax: 414-266-8712; jmiano{at}post.its.mew.edu.

^¶ Current address: Hamon Center for Basic Cancer Research, The University of Texas, Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd., Dallas, TX 75235-9148. Tel.: 214-648-1187; Fax: 214-648-1196.

Abstract

Although several genes are considered markers for vascular smooth muscle cell (SMC) differentiation, few have been rigorously tested for SMC specificity in mammals, particularly during development where considerable overlap exists between different muscle gene programs. Here we describe the temporospatial expression pattern of the SMC calponin gene (formerly h1 or basic calponin) during mouse embryogenesis and in adult mouse tissues and cell lines. Whereas SMC calponin mRNA expression is restricted exclusively to SMCs in adult tissues, during early embryogenesis, SMC calponin transcripts are expressed throughout the developing cardiac tube as well as in differentiating SMCs. Transcription of the SMC calponin gene initiates at two closely juxtaposed sites in the absence of a consensus TATAA or initiator element. Transient transfection assays in cultured SMC demonstrated that high level SMC calponin promoter activity required no more than 549 nucleotides of 5′ sequence. In contrast to the strict cell type-specificity of SMC calponin mRNA expression, the SMC calponin promoter showed activity in several cell lines that do not express the endogenous SMC calponin gene. These results demonstrate that SMC calponin responds to cardiac and smooth muscle gene regulatory programs and suggest that the cardiac and smooth muscle cell lineages may share a common gene regulatory program early in embryogenesis, which diverges as the heart matures. The finding that the isolated SMC calponin promoter is active in a wider range of cells than the endogenous SMC calponin gene also suggests that long-range repression or higher order regulatory mechanism(s) are involved in cell-specific regulation of SMC calponin expression.

Footnotes

↵* This work was supported in part by grants from the National Institutes of Health, The Robert A. Welch Foundation, and the Muscular Dystrophy Association (to E. N. O.). 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.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank(™)/EMBL Data Bank with accession number(s) U37071 and U28932.
↵¹ The abbreviations used are:

SMC

smooth muscle cell(s)

SM α-actin

smooth muscle α-actin

SMMHC

smooth muscle myosin heavy chain

RASMC

rat aortic smooth muscle cell(s)

RACE

rapid amplification of cDNA end

PCR

polymerase chain reaction

nt

nucleotide(s)

Tricine

N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine.
↵² J. M. Miano and E. N. Olson, unpublished observations.
- Received October 25, 1995.
- Revision received January 2, 1996.