Oakwood College1, Biological Sciences, Huntsville, AL 35896 Western Michigan University2, Biological Sciences, Kalamazoo, MI 49008
The gene mup-4 (Muscle position-4) is critical for proper muscle and epithelial cell development in Caenorhabditis elegans (Gatewood and Bucher, 1997). The protein MUP-4 plays a role in the maintenance of muscle position and in epidermal morphogenesis during embryonic development. It has many similarities to muscle development proteins found in Drosophila melanogaster and even humans! Additionally, its predicted sequence has many similarities to the MUA-3 (Muscle attachment-3) protein, which is required to maintain mechanical tissue integrity in C. elegans. The genomic DNA encoding the mup-4 gene has been identified (Hong et al., 2001), and computer analysis predicts that the mup-4 gene contains 20 exons (http://www.wormbase.org/). The predicted gene structure has been partially confirmed by sequencing of mup-4 cDNAs. However, a number of predicted exons had not yet been shown to be present in transcripts from the gene. Further, the holes in the partial cDNA sequences might contain evidence for alternative splicing. Here, we present our sequencing data that fills in the gaps present in existing cDNA clones. The polymerase chain reaction (PCR) was used to amplify the inserts from Yugi Kohara’s cDNA clones yk1218, yk1120, and yk767, which are 4.2, 2.3, and 3.1 kBs respectively. In addition, we used PCR to amplify the 5’ end of the mup-4 gene from first-strand cDNA. We report the probability that alternative splicing takes place in mup-4 which may lead to the exclusion of key protein domains that are necessary for anchorage in the plasma membrane and attachment to intermediate filaments (the cytoskeleton). This raises the possibility that a previously undetected secreted form of the MUP-4 protein is produced when alternative splicing takes place. The existing anti-MUP-4 antibody and the GFP tag (Hong et al., 2001) label the intracellular domain, and would therefore not detect the secreted form predicted from our cDNA analyses.
[Abstract (DOC)]