Identification of a novel transcript of human PECAM-1 and its role in the transendothelial migration of monocytes and Ca2+ mobilization.
Platelet-endothelial cell adhesion molecule-1 (PECAM-1) is an integral component of endothelial cells and has been implicated in the transendothelial migration (TEM) of circulating leukocytes mediated by its 1st and 2nd extracellular immunoglobulin (Ig)-like domains and regulation of intracellular Ca(2+) homeostasis with its 6th domain. Up-to-date, little is known about the role of the 5th extracellular (Ig)-like domain. We have discovered a novel human PECAM-1 transcript missing the entire 7th exon, which encodes the 5th extracellular (Ig)-like domain of PECAM-1. A synthetic peptide with sequence homology to the 5th domain of PECAM-1 (JHS-7 peptide) and a corresponding polyclonal antibody (JHS-7 Ab) were prepared and their potential role in transendothelial migration and Ca(2+) influx was measured. The JHS-7 peptide and the antibody exerted a dose dependent decrease (50-80%) in the transendothelial migration of freshly isolated human monocytes and a promonocytic cell line (U-937) in resting HUVECs and HUVECs activated with tumor necrosis factor-alpha. This was accompanied by an increase in Ca(2+) influx and decrease in refilling of the intracellular Ca(2+) stores in HUVECs. In summary, we have identified a novel PECAM-1 transcript (Deltaexon 7) and shown that the 5th (Ig)-like domain of PECAM-1 plays a role in monocyte TEM and Ca(2+) homeostasis.
Wei
Heming
H
Laboratory of Atherosclerosis and Vascular Biology, Johns Hopkins Singapore-National Heart Centre Vascular Biology Program, National Heart Centre of Singapore, Singapore.
Song
Jie
J
Fang
Lu
L
Li
Guodong
G
Chatterjee
Subroto
S
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D002118:Calcium / Q000378:metabolism*; D002465:Cell Movement / Q000502:physiology*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009000:Monocytes / Q000166:cytology / Q000502:physiology*; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000737:chemistry* / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D014158:Transcription, Genetic / Q000235:genetics; D020298:U937 Cells
D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011994:Recombinant Proteins; D002118:Calcium