Expression pattern of alternatively spliced PECAM-1 isoforms in retinal vasculature.

PURPOSE Platelet/endothelial cell adhesion molecule-1 (PECAM-1) is a cell adhesion-signaling molecule with important roles in angiogenesis and inflammation. The alternative splicing of the PECAM-1 cytoplasmic domain modulates its adhesive properties during vascular development and angiogenesis. This study was designed to identify alternatively spliced PECAM-1 isoforms in human and murine retina and during postnatal vascularization of murine retina. METHODS RT-PCR, DNA sequencing, and Western blot analysis were utilized to examine the expression pattern of alternatively spliced PECAM-1 isoforms in human and mouse retina, and during vascularization of murine retina. RESULTS We demonstrate that the PECAM-1 cytoplasmic domain undergoes alternative splicing generating multiple isoforms in vascular beds of human and mouse retina. We detected full length PECAM-1 and an isoform that lacks exon 14 (Delta14) in human retina. Seven isoforms of PECAM-1 were detected in murine retina. These included full length, Delta12, Delta14, Delta15, Delta1215, Delta1415, and Delta12, 1415 PECAM-1 isoforms. The full length PECAM-1 was the predominant isoform detected in human retina, while the isoform lacking exon 1415 (Delta1415) was the predominant isoform detected in murine retina. In addition, the expression pattern of PECAM-1 isoforms changed during vascularization of murine retina. CONCLUSIONS PECAM-1 mRNA undergoes alternative splicing generating multiple isoforms in human and murine retinal vasculature. The regulated expression pattern of these isoforms may influence endothelial cell adhesive properties impacting vasculogenesis and angiogenesis.