Antiapoptotic action of hypoxia-inducible factor-1 alpha in human endothelial cells

Erik Z Yu, Ying-Yue Li, Xiu-Huai Liu, Elliott Kagan, Richard M McCarron
Laboratory Investigation; a Journal of Technical Methods and Pathology 2004, 84 (5): 553-61
Hypoxia-inducible factor-1 (HIF-1) is the major transcription factor involved in the adaptive response to hypoxia and consists of HIF-1 alpha and HIF-1 beta subunits. Indirect evidence suggests that HIF-1 alpha may exert both proapoptotic and antiapoptotic actions in response to hypoxia. In this study, we evaluated the effects of RNA interference (RNAi) targeting HIF-1 alpha messenger RNA (mRNA) on apoptosis in primary cultured human umbilical vascular endothelial cells (HUVECs) exposed to anoxia and reoxygenation (A/R). HUVECs were transfected with specific 21-nt small interfering RNA (siRNA) duplexes targeting HIF-1 alpha mRNA sequences or scrambled RNA duplexes and subjected either to normoxia for 251/2 h or to anoxia for 11/2 h, and subsequently normoxia for 24 h (A/R). Control samples were subjected to A/R but not transfected. HUVECs apoptosis was evaluated by Tdt-mediated dUTP nick end-labeling (TUNEL) assay and by activated caspase-3 immunostaining and immunoblotting. The efficacy of RNAi was assessed by knockdown of HIF-1 alpha mRNA and protein expression via in situ hybridization, real-time quantitative PCR, immunohistochemistry, and Western blotting. When compared with normoxic cultures, A/R significantly upregulated HIF- 1 alpha mRNA and protein expression in HUVECs, but did not appreciably alter the percentage of apoptotic cells. In contrast, a significantly greater proportion of HUVECs transfected with specific siRNA duplexes and exposed to A/R demonstrated evidence of apoptosis when compared with nontransfected cells. Transfection with specific siRNA duplexes knocked down HIF-1 alpha mRNA and protein expression in A/R-treated cells by approximately 60%, whereas transfection with scrambled siRNA duplexes had no noticeable effect on HIF-1 alpha expression. These findings strongly suggest that HIF-1 alpha exerts an antiapoptotic role in HUVECs stressed by anoxia.

Full Text Links

Find Full Text Links for this Article


You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Remove bar
Read by QxMD icon Read

Save your favorite articles in one place with a free QxMD account.


Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"