Abstract
CD44 molecules function as a receptor for various extracellular matrices. Recently, molecular structure of CD44 has been extensively analyzed and have been identified multiple isoforms produced by alternative splicing of mRNA.
In this study, we examined the expression of CD44 isoforms on different cell types isolated from periodontal tissue. In vitro cell lines of different cell types, human gingival fibroblasts (HGF), human periodontal ligament cells (HPDL) and human gingival epithelial cells (HGEC) were isolated and CD44 isoform expressions were analyzed. All of these in vitro cell lines expressed CD44 protein as determined by immunoprecipitation. Interestingly, the immunoprecipitated CD44 from HGEC showed higher molecular mass than those from HGF and HPDL.
To detect CD44 mRNA heterogeneity in details, reverse transcription polymerase chain reaction (RT-PCR) utilizing primer flanking the insertion site of alternatively spliced exons was introduced. All cells examined expressed one major band detected in the absence of alternatively spliced exons and additional bands. In particular, HGEC contained more abundant high molecular species in size than others. HGEC after confluent culture contained less amount of larger CD44 isoforms than the one before confluent culture.
These findings suggest that CD44 isoform expression in periodontal tissue is tissuespecifically regulated and its expression is modulated in epithelial cells.
