The expression and localization of RNase and RNase inhibitor in blood cells and vascular endothelial cells in homeostasis of the vascular system.
RNA may be released from vascular cells including endothelial cells in the event of injury and in vascular disease. Extracellular RNAs have been recognized as novel procoagulant and permeability-increasing factors. Extracellular RNA may function as inflammatory host alarm signals that serve to amplify the defense mechanism, but it may provide important links to thrombus formation. Extracellular RNA is degraded by RNase. We propose that RNase and its inhibitor RNase inhibitor (RI) act as modulators of homeostasis in the vasculature to control the functions of extracellular RNA. We aimed to investigate the expression and localization of RNase 1 and RI in cells that contact blood, such as platelets, mononuclear cells, polymorphonuclear cells, and red blood cells. RNase 1 and RI expression and localization in blood cells were compared with those in the human umbilical vein endothelial cell line, EAhy926. Additionally, we further investigated the effect of thrombin on the expression of RNase 1 and RI in platelets. We used an RNase activity assay, reverse transcription-polymerase chain reaction, western blot, immunocytochemistry, transmission electron microscopy, and immunoelectron microscopy (pre- and post-embedding methods). RNase activity in the supernatant from EAhy926 cells was 50 times than in blood cells (after 60 min). RNase 1 mRNA and protein expression in EAhy926 cells was highest among the cells examined. However, RI mRNA and protein expression was similar in most cell types examined. Furthermore, we observed that RNase 1 and von Willebrand factor were partially colocalized in EAhy926 cells and platelets. In conclusion, we propose that high RNase activity is ordinarily released from endothelial cells to support anticoagulation in the vasculature. On the other hand, platelets and leukocytes within thrombi at sites of vascular injury show very low RNase activity, which may support hemostatic thrombus formation. However, activated platelets and leukocytes may accelerate pathologic thrombus formation.
Laboratory Molecular Genetics of Hematology, Field of Applied Laboratory Science, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Ayaka
A
Ohashi
Laboratory Molecular Genetics of Hematology, Field of Applied Laboratory Science, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Aya
A
Murata
Anatomy and Physiological Science, Field of Applied Laboratory Science, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Yuichiro
Y
Cho
Instrumental Analysis Research Center, Tokyo Medical and Dental University, Tokyo, Japan.
Shizuko
S
Ichinose
Instrumental Analysis Research Center, Tokyo Medical and Dental University, Tokyo, Japan.
Yuriko
Y
Sakamaki
Laboratory Molecular Genetics of Hematology, Field of Applied Laboratory Science, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Miwako
M
Nishio
Anatomy and Physiological Science, Field of Applied Laboratory Science, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Osamu
O
Hoshi
Institute for Biochemistry, Medical Faculty, Justus-Liebig-Universität, Giessen, Germany.
Silvia
S
Fischer
Institute for Biochemistry, Medical Faculty, Justus-Liebig-Universität, Giessen, Germany.
Klaus T
KT
Preissner
Laboratory Molecular Genetics of Hematology, Field of Applied Laboratory Science, Graduate School of Health Care Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Takatoshi
T
Koyama
D001773:Blood Cells / Q000378:metabolism*; D001777:Blood Coagulation / Q000502:physiology; D001792:Blood Platelets / Q000378:metabolism; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism*; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D007962:Leukocytes / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism*; D013917:Thrombin / Q000378:metabolism; D013927:Thrombosis / Q000378:metabolism; D014471:Umbilical Veins / Q000378:metabolism; D014652:Vascular Diseases / Q000378:metabolism; D014841:von Willebrand Factor / Q000378:metabolism
D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D014841:von Willebrand Factor; D012260:Ribonucleases; D013917:Thrombin