title: Cutting Edge: Internalization of transduced E-selectin by cultured human endothelial cells: comparison of dermal microvascular and umbilical vein cells and identification of a phosphoserine-type di-leucine motif.
abstract: Persistent E-selectin expression on human dermal microvascular endothelial cells (HDMEC), believed to mediate skin-specific T cell homing, results from a slow rate of surface protein internalization after cytokine induction. Following transduction of unactivated HDMEC with E-selectin cDNA, the rate of internalization was largely independent of increasing levels of surface protein expression, leading to prolonged t(1/2) values of over 4 h, comparable to that observed following cytokine induction. In HUVEC, the rate of internalization increased with surface expression level, leading to an essentially constant t(1/2) of under 2 h. Thus, the internalization process rather than cytokine responsiveness or E-selectin structure underlies the difference in endothelial cell behavior. Mutational analysis of the cytoplasmic region demonstrated a role for a di-leucine-type motif involving I588 and L589 but not for a putative tyrosine-type motif. Control of E-selectin surface expression appears to be phosphoserine dependent, since alanine but not aspartic acid substitution for S581 slows E-selectin internalization.
authors.affiliation: Interdepartmental Program in Vascular Biology and Transplantation, Department of Dermatology, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA. martin.kluger@yale.edu
authors.forename: Martin S
authors.initials: MS
authors.lastname: Kluger
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Shiao
authors.forename: Alfred L M
authors.initials: AL
authors.lastname: Bothwell
authors.forename: Jordan S
authors.initials: JS
authors.lastname: Pober
mesh_terms: D020816:Amino Acid Motifs; D002196:Capillaries / Q000166:cytology; D002478:Cells, Cultured; D020405:Dermis / Q000166:cytology*; D019040:E-Selectin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis; D004730:Endothelium, Vascular / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D007930:Leucine / Q000032:analysis; D010768:Phosphoserine / Q000032:analysis; D012190:Retroviridae / Q000235:genetics; D014161:Transduction, Genetic; D014471:Umbilical Veins / Q000166:cytology*
chemical_list: D019040:E-Selectin; D010768:Phosphoserine; D007930:Leucine