c-Abl mediates endothelial apoptosis induced by inhibition of integrins alphavbeta3 and alphavbeta5 and by disruption of actin.
Inhibition of integrins alphavbeta3 and alphavbeta5 in human brain microvascular endothelial cells (HBMECs) by the function-blocking peptide RGDfV induces loss of spreading on vitronectin, cell detachment, and apoptosis. We demonstrate that cell detachment is not required for apoptosis because plating on bovine serum albumin-blocked poly-L-lysine (allows attachment, but not integrin ligation and cell spreading) also induced apoptosis. Latrunculin B (LatB), which inhibits F-actin polymerization, induced transient loss of HBMEC spreading on vitronectin, but not their detachment, and induced apoptosis despite recovery of cell spreading. However, LatB did not cause apoptosis in 5 tumor cell lines. In HBMECs, both LatB and RGDfV induced transient Y412 and Y245 phosphorylation of endogenous c-Abl, a nonreceptor tyrosine kinase that reciprocally regulates F-actin. LatB also induced nuclear translocation of c-Abl in HBMECs. STI-571 (imatinib), a targeted therapy for BCR-ABL1(+) leukemias and inhibitor of c-Abl, platelet-derived growth factor receptor, and c-Kit, decreased endothelial apoptosis. LatB-induced HBMEC apoptosis, and its inhibition by STI-571 also occurred in a 3-dimensional collagen model, supporting physiologic relevance. Last, siRNA to c-Abl (but not nonspecific siRNA) also inhibited RGDfV- and LatB-induced apoptosis. Thus, endogenous c-Abl mediates endothelial apoptosis induced by inhibition of integrins alphavbeta3/alphavbeta5 or by LatB-induced disruption of F-actin.
Xu
Jingying
J
Department of Pediatrics, Neil Bogart Memorial Laboratories, Division of Hematology-Oncology, Saban Research Institute at Childrens Hospital Los Angeles, USA.
Millard
Melissa
M
Ren
Xiuhai
X
Cox
Orla T
OT
Erdreich-Epstein
Anat
A
D008841:Actin Cytoskeleton / Q000187:drug effects / Q000648:ultrastructure; D000199:Actins / Q000037:antagonists & inhibitors*; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002417:Cattle; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D048430:Cell Shape / Q000187:drug effects; D003470:Culture Media / Q000494:pharmacology; D016895:Culture Media, Serum-Free; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects; D005312:Fetal Blood; D016313:Genes, abl; D005909:Glioblastoma / Q000473:pathology; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000037:antagonists & inhibitors*; D008527:Medulloblastoma / Q000473:pathology; D053078:Membrane Potential, Mitochondrial; D009447:Neuroblastoma / Q000473:pathology; D016315:Proto-Oncogene Proteins c-abl / Q000037:antagonists & inhibitors / Q000502:physiology*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D019030:Receptors, Vitronectin / Q000037:antagonists & inhibitors*; D053778:Thiazolidines / Q000494:pharmacology
D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D003470:Culture Media; D016895:Culture Media, Serum-Free; D039302:Integrin alphaVbeta3; D034741:RNA, Small Interfering; D019030:Receptors, Vitronectin; D053778:Thiazolidines; C064660:integrin alphaVbeta5; D016315:Proto-Oncogene Proteins c-abl; C037068:latrunculin B