Differential expression of mouse laminin γ2 and γ2*chain transcripts

Laminins are large heterotrimeric basement membrane proteins that consist of alpha, beta, and gamma chains. We have previously shown that the human gamma 2 and gamma 2* transcripts result from the alternative use of the LAMC2 gene 3'-end exons. To explore the biological significance of the alternative gamma 2 transcripts, we isolated the cDNA coding for the mouse laminin gamma 2* transcript, characterized the 3'-end of the murine LAMC2 gene, and studied the expression of alternative gamma 2 transcripts in several mouse tissues. The sequence reported here is the first one containing a full-length gamma 2* 3'-UTR from any species. The mouse gamma 2* transcript is 4110 bases and encodes a putative polypeptide of 1110 amino acids. This polypeptide lacks the C-terminal cysteine residue thought to be important fur heterotrimer formation. The mouse gamma 2* transcript was found to be expressed in several tissues by polymerase chain reaction (PCR), but at very low levels. The dearest signals were obtained on embryonic day 7, and in heart and testis of adult tissues. When the laminin gamma 2* transcript expression pattern was compared with that of the gamma 2 chain, a similar tissue distribution was observed. There was, however, a significant difference in expression levels. The longer gamma 2 transcript was found to be much more abundant than the shorter gamma 2* variant.