Mechanisms of VE-cadherin processing and degradation in microvascular endothelial cells.
VE-cadherin is an endothelial-specific cadherin that plays important roles in vascular morphogenesis and growth control. To investigate the mechanisms by which endothelial cells regulate cadherin cell surface levels, a VE-cadherin mutant containing the non-adhesive interleukin-2 (IL-2) receptor extracellular domain and the VE-cadherin cytoplasmic tail (IL-2R-VE-cadcyto) was expressed in microvascular endothelial cells. Expression of the IL-2R-VE-cadcyto mutant resulted in the internalization of endogenous VE-cadherin and in a dramatic decrease in endogenous VE-cadherin levels. The internalized VE-cadherin co-localized with early endosomes, and the lysosomal inhibitor chloroquine dramatically inhibited the down-regulation of VE-cadherin in cells expressing the IL-2R-VE-cadcyto mutant. Chloroquine treatment also resulted in the accumulation of a VE-cadherin fragment lacking the beta-catenin binding domain of the VE-cadherin cytoplasmic tail. The formation of the VE-cadherin fragment could be prevented by treating endothelial cells with proteasome inhibitors. Furthermore, inhibition of the proteasome prevented VE-cadherin internalization and inhibited the disruption of endothelial intercellular junctions by the IL-2RVE-cadcyto mutant. These results provide new insights into the mechanisms of VE-cadherin processing and degradation in microvascular endothelial cells.
Xiao
Kanyan
K
Department of Dermatology and Emory Skin Diseases Research Center, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Allison
David F
DF
Kottke
Margaret D
MD
Summers
Susan
S
Sorescu
George P
GP
Faundez
Victor
V
Kowalczyk
Andrew P
AP
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D015703:Antigens, CD; D015153:Blotting, Western; D019556:COS Cells; D015820:Cadherins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D002738:Chloroquine / Q000494:pharmacology; D003546:Cysteine Endopeptidases; D011992:Endosomes / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D017353:Gene Deletion; D015870:Gene Expression; D005822:Genetic Vectors; D006801:Humans; D007365:Intercellular Junctions / Q000187:drug effects; D007668:Kidney; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008833:Microcirculation; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors; D016296:Mutagenesis; D046988:Proteasome Endopeptidase Complex; D015375:Receptors, Interleukin-2 / Q000235:genetics; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D012867:Skin / Q000098:blood supply; D014162:Transfection; D000099152:Cadherin 5
D015703:Antigens, CD; D015820:Cadherins; D002738:Chloroquine; D003546:Cysteine Endopeptidases; D009097:Multienzyme Complexes; D046988:Proteasome Endopeptidase Complex; D015375:Receptors, Interleukin-2; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D000099152:Cadherin 5