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.
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.
Powell
John D
JD
Biology Department, Monmouth University, West Long Branch, New Jersey 07764, USA.
Elshtein
Ronit
R
Forest
Daniel J
DJ
Palladino
Michael A
MA
D000818:Animals; D004822:Epididymis / Q000737:chemistry; D015870:Gene Expression; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007511:Ischemia / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D010413:Penis / Q000737:chemistry; D010766:Phosphorylation; D012333:RNA, Messenger / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013086:Spermatic Cord Torsion / Q000378:metabolism; D013737:Testis / Q000098:blood supply* / Q000737:chemistry; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D014649:Vas Deferens / Q000737:chemistry
D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D014157:Transcription Factors