Nitrite-mediated S-nitrosylation of caspase-3 prevents hypoxia-induced endothelial barrier dysfunction.
BACKGROUND
Hypoxia is a significant perturbation that exacerbates endothelial barrier dysfunction, contributing to the disruption of vascular homeostasis and the development of various diseases such as atherosclerosis and metastasis of tumors. To date, it is not known what strategy might be used to counter the effect of hypoxia on endothelial permeability.


OBJECTIVE
This study investigated the role of nitrite in regulating vascular integrity under hypoxic conditions.


RESULTS
We found denitrosylation and the resulting activation of caspase-3 to be critical for hypoxia-induced endothelial permeability. Nitrite treatment led to S-nitrosylation and the inactivation of caspase-3, suppressing the barrier dysfunction of endothelia caused by hypoxia. This process required the conversion of nitrite to bioactive nitric oxide in a nitrite reductase-dependent manner. Using primary human umbilical vein endothelial cells as a model, we showed that in the presence of nitrite, the S-nitrosylated and inactivated form of caspase-3 was unable to cleave β-catenin, a key component in the VE-cadherin complex. Therefore, nitrite treatment led to the maintenance of VE-cadherin-mediated adherens junctions under hypoxic conditions. In in vivo experiments using a zebrafish model, nitrite was found to protect blood vessels from hypoxia-induced vascular leakage.


CONCLUSIONS
These results are the first to demonstrate that nitrite plays a critical role in the protection of endothelial barrier function against hypoxic insult. Our findings show that nitrite holds great potential for the treatment of diseases associated with hypoxia-induced disorder of vascular homeostasis.
Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.
Yen-Chun
YC
Lai
Kuan-Ting
KT
Pan
Gao-Fong
GF
Chang
Chia-Hao
CH
Hsu
Kay-Hooi
KH
Khoo
Chen-Hsiung
CH
Hung
Yun-Jin
YJ
Jiang
Feng-Ming
FM
Ho
Tzu-Ching
TC
Meng
D022005:Adherens Junctions / Q000187:drug effects / Q000502:physiology; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism*; D002417:Cattle; D002463:Cell Membrane Permeability / Q000187:drug effects* / Q000502:physiology*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000503:physiopathology*; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D000860:Hypoxia / Q000150:complications / Q000503:physiopathology*; D051379:Mice; D023421:Models, Animal; D009569:Nitric Oxide / Q000378:metabolism; D009573:Nitrites / Q000494:pharmacology*; D015027:Zebrafish; D051176:beta Catenin / Q000378:metabolism; D000099152:Cadherin 5
D015703:Antigens, CD; D015820:Cadherins; D053148:Caspase 3; D009569:Nitric Oxide; D009573:Nitrites; D051176:beta Catenin; D000099152:Cadherin 5