Powell JD, Elshtein R, Forest DJ, Palladino MA. Stimulation of hypoxia-inducible factor-1 alpha (HIF-1alpha) protein in the adult rat testis following ischemic injury occurs without an increase in HIF-1alpha messenger RNA expression.
Biol Reprod 2002;
67:995-1002. [PMID:
12193413 DOI:
10.1095/biolreprod.101.002576]
[Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Hypoxia-inducible factor 1 (HIF-1) is a transcription factor composed of alpha and beta subunits. Stabilized from proteasome degradation and activated by hypoxia, HIF-1 stimulates expression of hypoxia-sensitive genes that mediate oxygen homeostasis in many tissues. Our hypothesis is that HIF-1 is involved in the cellular response to hypoxia in the ischemic testis. Goals of this study were to determine if HIF-1alpha mRNA is expressed in the testis, epididymis, and accessory sex glands of adult Sprague-Dawley rats and to determine if HIF-1alpha mRNA and protein expression in the testis is affected by experimentally induced ischemia. Total RNA from reproductive organs of adult rats was analyzed by relative reverse transcription-polymerase chain reaction (RT-PCR) analysis. HIF-1alpha mRNA showed equal expression in testis, all segments of epididymis, ductus deferens, accessory sex glands, and penis. To examine the effects of ischemia on HIF-1alpha mRNA and protein expression in the testis, rats were subjected to unilateral testicular ischemia by placing a ligature around spermatic artery or ischemia-inducing experimental torsion and reperfusion. RT-PCR revealed that HIF-1alpha mRNA expression at all times of ischemic treatment and reperfusion was unchanged compared with normoxic controls. HIF-1alpha protein was detected by immunoblot analysis of nuclear protein extracts from normoxic testes. Steady-state levels of HIF-1alpha protein were stimulated by 15 min of ischemia and showed a 2-fold increase at 30 min and 1, 3, and 6 h. HIF-1alpha protein was also elevated by experimental torsion and reperfusion compared with normoxic controls. These results support the hypothesis that HIF-1 may play a role in the cellular response to hypoxia in the ischemic testis.
Collapse