Regulation of tie2 expression by angiopoietin--potential feedback system.
To study a potential feedback system in the angiopoietin (Ang)-Tie2 system, the authors examined effects of Ang1 and Ang2 on Tie2 expression on human umbilical vein endothelial cells (HUVECs) with or without stimulation by a potent inflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha). Ang1, but not Ang2, down-regulated Tie2 expression on HUVECs without TNF-alpha stimulation. Both Ang1 and Ang2 attenuated TNF-alpha-induced Tie2 up-regulation. Regulation of Tie2 expression by Ang1 or Ang2 was not dependent on phosphatidylinositol 3-kinase. The Ang-Tie2 system appears to have an autoregulatory feedback system that may be regulating the overall activity of the Tie2 system in both physiological and pathological conditions.
Hashimoto
Tomoki
T
Department of Anesthesia and Perioperative Care and the Center for Cerebrovascular Research, University of California, San Francisco, California 94110, USA. hashimot@anesthesia.ucsf.edu
Wu
Yongqin
Y
Boudreau
Nancy
N
Li
Jenny
J
Matsumoto
Melissa
M
Young
William
W
D042683:Angiopoietin-1 / Q000378:metabolism* / Q000494:pharmacology; D042702:Angiopoietin-2 / Q000378:metabolism* / Q000494:pharmacology; D002460:Cell Line; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D025461:Feedback, Physiological / Q000187:drug effects / Q000502:physiology*; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology; D006801:Humans; D019869:Phosphatidylinositol 3-Kinases / Q000187:drug effects / Q000378:metabolism; D042787:Receptor, TIE-2 / Q000187:drug effects / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
C467630:ANGPT1 protein, human; D042683:Angiopoietin-1; D042702:Angiopoietin-2; D014409:Tumor Necrosis Factor-alpha; D019869:Phosphatidylinositol 3-Kinases; D042787:Receptor, TIE-2