Primary Structure, Developmental Expression, and Immunolocalization of the Murine Laminin α4 Chain*
- Antti Iivanainenद,
- Jarkko Kortesmaa‡§,
- Carin Sahlberg‖,
- Takako Morita‡,
- Ulrich Bergmann‡,
- Irma Thesleff‖ and
- Karl Tryggvason‡§**
- From the ‡Department of Medical Biochemistry and Biophysics, Division of Matrix Biology, Karolinska Institute, S-171 77 Stockholm, Sweden, §Biocenter and Department of Biochemistry, University of Oulu, SF-90570 Oulu, Finland, and¶Department of Anatomy and Embryology, Faculty of Veterinary Medicine and ‖Institute of Biotechnology, University of Helsinki, FIN-00014 Helsinki, Finland
Abstract
The complete primary structure of the mouse laminin α4 chain was derived from cDNA clones. The translation product contains a 24-residue signal peptide preceding the mature α4 chain of 1,792 residues. Northern analysis on whole mouse embryos revealed that the expression was weak at day 7, but it later increased and peaked at day 15. In adult tissues the strongest expression was observed in lung and cardiac and skeletal muscles. Weak expression was also seen in other adult tissues such as brain, spleen, liver, kidney, and testis. By in situ hybridization of fetal and newborn tissues, expression of the laminin α4 chain was mainly localized to mesenchymal cells. Strong expression was seen in the villi and submucosa of the developing intestine, the mesenchymal stroma surrounding the branching lung epithelia, and the external root sheath of vibrissae follicles, as well as in cardiac and skeletal muscle fibers. In the developing kidney, intense but transient expression was associated with the differentiation of epithelial kidney tubules from the nephrogenic mesenchyme. Immunohistologic staining with affinity-purified IgG localized the laminin α4 chain primarily to lung septa, heart, and skeletal muscle, capillaries, and perineurium.
Footnotes
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↵* This work was supported in part by grants from the Swedish Medical Research Council, Swedish Cancer Foundation, Academy of Finland, Sigrid Juselius Foundation, and Finland’s Cancer Institute.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be 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) U59865.
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↵** To whom correspondence should be addressed. Tel.: 46-8-728-7720; Fax: 46-8-31-34-45; E-mail: Karl.Tryggvason{at}mbb.ki.se.
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↵1 The abbreviations used are: kb, kilobase(s); bp, base pair(s); PCR, polymerase chain reaction.
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- Received January 15, 1997.
- Revision received June 19, 1997.
