Increased Expression of Integrin and Receptor Tyrosine Kinase Genes During Autograft Fusion in the Sponge Geodia cydonium

Recently cDNAs coding for cell surface molecules have been isolated from sponges. The molecules for α-integrin, galectin, and receptor tyrosine kinase (RTK), obtained from the marine sponge, Geodia cydonium, have been described earlier. In the present study also the cDNA for one putative β-integrin has been identified from G. cydonium. The deduced aa sequence comprises the characteristic signatures, found in other metazoan β-integrin molecules; the estimated size is 95,215 Da. To obtain first insights into the molecular events which proceed during autograft fusion, the expressions of these genes were determined on transcriptional and translational level. The cDNAs as well as antibodies raised against the recombinant sponge proteins α-integrin, RTK and galectin were used and Northern blot experiments and immunocytochemical analyses have been performed. The results show that transcription of the two subunits of an integrin receptor as well as of the RTK are strongly upregulated after grafting; levels of > 1...