Integrins are heterodimeric transmembrane receptors composed of an α and a β subunit, that are expressed on the surface of all metazoan cells. These bidirectional signaling molecules are involved in many well-known aspects of cell function, although the role of integrins in early embryonic development remains a mystery. The purpose of this study was to characterize S. purpuratus integrins and determine if they are necessary for early embryonic development. Full length cDNA sequences for four incomplete gene predictions, αC, αD, αF, and βD, were determined by amplifying overlapping fragments and sequencing EST clones. Each cDNA has a single open reading frame predicting a protein with canonical integrin features. QPCR results show αC, αD, and βD are expressed in the embryo at relatively constant levels during the first 96 hours of development. αF is expressed in blastulae, during morphogenesis and tissue differentiation, at up to 35 times the levels of mRNA in the egg. Using a morpholino antisense oligonucleotide to block translation of αC results in a higher than normal mortality rate (57.1%) by 24 hours of development and 36.7% of embryos during this period have defects in aspects of cell division. These results indicate that αC is an essential gene for early development and that it may function in coordination of mitosis and cytokinesis. The expression of multiple subunits and the demonstration that αC has an essential role suggests that there are several non-overlapping functions for integrins in early embryonic development.

Integrins are heterodimeric transmembrane receptors composed of an α and a β subunit, that are expressed on the surface of all metazoan cells. These bidirectional signaling molecules are involved in many well-known aspects of cell function, although the role of integrins in early embryonic development remains a mystery. The purpose of this study was to characterize S. purpuratus integrins and determine if they are necessary for early embryonic development. Full length cDNA sequences for four incomplete gene predictions, αC, αD, αF, and βD, were determined by amplifying overlapping fragments and sequencing EST clones. Each cDNA has a single open reading frame predicting a protein with canonical integrin features. QPCR results show αC, αD, and βD are expressed in the embryo at relatively constant levels during the first 96 hours of development. αF is expressed in blastulae, during morphogenesis and tissue differentiation, at up to 35 times the levels of mRNA in the egg. Using a morpholino antisense oligonucleotide to block translation of αC results in a higher than normal mortality rate (57.1%) by 24 hours of development and 36.7% of embryos during this period have defects in aspects of cell division. These results indicate that αC is an essential gene for early development and that it may function in coordination of mitosis and cytokinesis. The expression of multiple subunits and the demonstration that αC has an essential role suggests that there are several non-overlapping functions for integrins in early embryonic development.