Identification and functional characterization of lactadherin, an agglutinating glycoprotein from the chordate Styela clava

Lactadherin is an extracellular matrix glycoprotein with stimulating agglutination ability that plays crucial roles in animal immunology. In the present study, a novel lactadherin, Sc-lactadherin, was identified from the marine invertebrate chordate, Styela clava. Its full-length cDNA consisted of 579 bps, encoding 193 amino acids with a coagulation FA58C domain. Recombinant Sc-lactadherin via a prokaryotic expression system showed strong hemocyte fusion activity. Therefore, we further examined its effects on cell behaviors using human umbilical vein endothelial cells (HUVECs) and human cervical cancer (HeLa) cells. Recombinant Sc-lactadherin significantly increased the proliferation rate of HUVECs and HeLa cells and improved the cell migration rate of HUVECs. These results demonstrated that the lactadherin identified from the marine ascidian displayed the agglutinating activity. Functional characterization of the recombinant protein showed that it promoted cell proliferation and migration, indicating the potential roles of Sc-lactadherin in immunology and organogenesis in marine ascidians.