Heat shock cognate protein 70 is essential for Akt signaling in endothelial function.
OBJECTIVE
Heat shock protein 70s (Hsp70s) are molecular chaperones that protect cells from damage in response to various stress stimuli. However, the functions and mechanisms in endothelial cells (ECs) have not been examined. Herein, we investigate the role of Hsp70s, including heat shock cognate protein 70 (Hsc70), which is constitutively expressed in nonstressed cells (ie, ECs).


RESULTS
The Hsp70 inhibitor, KNK437, significantly decreased vascular endothelial growth factor (VEGF)-induced cell migration and tube formation in vitro. KNK437 inhibited the phosphorylation of VEGF-induced Akt and endothelial nitric oxide synthase (eNOS) in human umbilical vein endothelial cells. In a mouse hind limb model of vascular insufficiency, intramuscular inhibition of Hsp70s attenuated collateral and capillary vessel formation. Silencing the Hsc70 gene by short interfering RNA abolished VEGF-induced Akt phosphorylation and VEGF-stimulated human umbilical vein endothelial cell migration and tube formation. As the molecular mechanisms, Hsc70 knockdown reduced the expression of phosphatidylinositol 3-kinase.


CONCLUSIONS
Collectively, Hsc70 plays a significant role in ECs via the phosphatidylinositol 3-kinase/Akt pathway. Hsc70 may provide the basis for the development of new therapeutic strategies for angiogenesis.
Shiota
Masayuki
M
Department of Pharmacology, Osaka City University Medical School, 1-4-3 Asahi-machi, Abeno-ku, Osaka 545-8585, Japan. sio@med.osaka-cu.ac.jp
Kusakabe
Hiromi
H
Izumi
Yasukatsu
Y
Hikita
Yuko
Y
Nakao
Takafumi
T
Funae
Yoshihiko
Y
Miura
Katsuyuki
K
Iwao
Hiroshi
H
D000818:Animals; D001559:Benzhydryl Compounds / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D050883:HSC70 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D006614:Hindlimb / Q000098:blood supply; D006801:Humans; D007511:Ischemia / Q000503:physiopathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018919:Neovascularization, Physiologic / Q000502:physiology; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology*; D011760:Pyrrolidinones / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D001559:Benzhydryl Compounds; D050883:HSC70 Heat-Shock Proteins; C410027:KNK 437; D011760:Pyrrolidinones; D042461:Vascular Endothelial Growth Factor A; D052250:Nitric Oxide Synthase Type III; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt