Thrombomodulin protects endothelial cells from a calcineurin inhibitor-induced cytotoxicity by upregulation of extracellular signal-regulated kinase/myeloid leukemia cell-1 signaling.
OBJECTIVE
We have recently reported that recombinant human soluble thrombomodulin (rTM) counteracted capillary leakage associated with engraftment, as well as sinusoidal obstructive syndrome after hematopoietic stem cell transplantation. These observations prompted us to explore whether rTM possessed cytoprotective effects on endothelial cells.


RESULTS
Exposure of human umbilical vein endothelial cells to rTM induced expression of antiapoptotic protein myeloid leukemia cell-1 through the activation of extracellular signal-regulated kinase in these cells. Additional studies found that exposure of human umbilical vein endothelial cells to cyclosporine A and FK506, an immunosuppressant used for the individuals receiving hematopoietic stem cell transplantation, induced apoptosis, which was attenuated when human umbilical vein endothelial cells were exposed to these agents in the presence of rTM. Further studies using deletion mutants of thrombomodulin (TM) identified that the epidermal growth factor domain of TM possessed cytoprotective effects. A single nucleotide substitution at codon 376 or 424 of TM, which impairs the ability of TM to produce activated protein C or bind to thrombin, respectively, did not hamper the cytoprotective effects of TM, which suggested that cytoprotective effects of rTM were distinctive from those of activated protein C.


CONCLUSIONS
TM may be useful for prevention, as well as treatment of endothelial cell damage after hematopoietic stem cell transplantation.
Department of Hematology and Respiratory Medicine, Kochi University, Nankoku, Kochi 783-8505, Japan. ikezoet@kochi-u.ac.jp
Takayuki
T
Ikezoe
Jing
J
Yang
Chie
C
Nishioka
Goichi
G
Honda
Mutsuo
M
Furihata
Akihito
A
Yokoyama
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D019556:COS Cells; D019703:Calcineurin / Q000378:metabolism; D065095:Calcineurin Inhibitors; D002522:Chlorocebus aethiops; D016572:Cyclosporine / Q000633:toxicity*; D019610:Cytoprotection; D004305:Dose-Response Relationship, Drug; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005260:Female; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D006801:Humans; D007166:Immunosuppressive Agents / Q000633:toxicity*; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D018919:Neovascularization, Physiologic; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010766:Phosphorylation; D011486:Protein C / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D016559:Tacrolimus / Q000633:toxicity*; D013917:Thrombin / Q000378:metabolism; D018180:Thrombomodulin / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection
D065095:Calcineurin Inhibitors; D007166:Immunosuppressive Agents; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D011486:Protein C; D047428:Protein Kinase Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins; C546931:THBD protein, human; D018180:Thrombomodulin; D016572:Cyclosporine; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D048049:Extracellular Signal-Regulated MAP Kinases; D019703:Calcineurin; D013917:Thrombin; D016559:Tacrolimus