Cloning of the LamA3 gene encoding the alpha 3 chain of the adhesive ligand epiligrin. Expression in wound repair

• Published in: The Journal of biological chemistry 1994-09, Vol.269 (36), p.22779-22787
• Main Authors: Ryan, M C, Tizard, R, VanDevanter, D R, Carter, W G
• Format: Article
• Language: English
• Subjects: alpha 3 chain; Amino Acid Sequence; Animals; Base Sequence; Blotting, Northern; cDNA; Cell Adhesion Molecules - biosynthesis; Cell Adhesion Molecules - chemistry; Cell Adhesion Molecules - genetics; Chromosome Mapping; Chromosomes, Human, Pair 8; cloning; Cloning, Molecular; DNA Primers; DNA, Complementary - isolation & purification; DNA, Complementary - metabolism; Drosophila - genetics; epiligrin; foreskin; Gene Expression; homology; Humans; In Situ Hybridization, Fluorescence; Kalinin; Keratinocytes - metabolism; LamA3 gene; laminin; Laminin - chemistry; Laminin - genetics; Macromolecular Substances; man; Molecular Sequence Data; prediction; RNA, Messenger - analysis; RNA, Messenger - biosynthesis; role; Sequence Homology, Amino Acid; Transcription, Genetic; Vertebrates; Wound Healing; Wounds and Injuries - metabolism; Wounds and Injuries - pathology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/s0021-9258(17)31713-1

We have isolated cDNA clones encoding the entire 170-kDa chain of epiligrin (alpha 3Ep) and a genomic clone encoding the alpha 3Ep gene (LamA3). Analysis of multiple cDNA clones revealed two distinct transcripts (alpha 3EpA and alpha 3EpB). Sequencing of the alpha 3EpA transcript indicated sequence and structural homology to laminin alpha 1 and alpha 2 chains that extend from domain IIIa through the carboxyl-terminal G domain. The alpha 3EpB transcript encodes a larger amino-terminal domain and contains additional epidermal growth factor repeats and sequences corresponding to domain IV of alpha 1 laminin. Fluorescence in situ hybridization indicated that the LamA3 gene is located on chromosome 18q11.2, a locus distinct from the LamA1 gene (18p11.3). The G domain of the epiligrin alpha 3 chain contains five subdomains that are individually related to the G subdomains reported for Drosophila and vertebrate laminin alpha chains. Sequence divergence within the G domain of alpha 3 epiligrin suggests that it is functionally distinct from laminin, consistent with our previous report showing that epiligrin interacts with different integrin adhesion receptors. Analysis of RNA from human foreskin keratinocytes (HFKs) identified multiple epiligrin transcripts that were down-regulated by viral transformation and differentiation. In contrast, epiligrin expression was up-regulated in wound sites of human skin.