Stage-specific expression of Gadd45 induced by X-irradiation in rat spermatogenesis.
OBJECTIVE
Gadd45 is involved in the response to DNA damage in somatic cells. The effect of X-irradiation and chemical treatments on expression of Gadd45 and two other 53-regulated genes, p21 and cyclin-G, was studied in rat testis.


METHODS
The reverse-transcriptase polymerase chain reaction (RT-PCR) was performed on testis extracts of control, X-irradiated (6Gy), etoposide (10 mg kg(-1)) and adriamycin (5mg kg(-1))-treated rats. For stage-specific analysis, seminiferous tubules were isolated and segments representing the 14 epithelial stages were obtained.


RESULTS
In whole testis extracts, increases in Gadd45, p21 and cyclin-G expression were detectable after irradiation, but not after etoposide or adriamycin treatments. Analysis of fractions consisting of defined epithelial stages showed a high expression of Gadd45 in stages VII-XII and of p21 in stages VII-VIII. Irradiation significantly increased the level of Gadd45 mRNA in stages VI-VIII and of p21 mRNA in stages VI-I. Although no overall increase could be observed in whole testis samples of the etoposide-treated rat, stage-specific analysis revealed an induction of p21 expression in stages XIII-I. Gadd45 and cyclin-G mRNA were localized to spermatocytes and round spermatids known to express p21.


CONCLUSIONS
Although X-irradiation, etoposide and adriamycinare known spermatogenic mutagens and activators of apoptosis, only X-rays induce slightly Gadd45 expression in testis. This small induction was very stage specific.
West
A
A
Department of Medical Genetics, University of Turku, Kiinamyllynkatu 10, FIN-20520 Turku, Finland. annwes@utu.fi
Priante
G
G
Lähdetie
J
J
D000818:Animals; D017209:Apoptosis; D056746:Cyclin G; D056766:Cyclin G1; D016213:Cyclins / Q000096:biosynthesis; D004317:Doxorubicin / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology; D017403:In Situ Hybridization; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000096:biosynthesis; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012671:Seminiferous Tubules / Q000187:drug effects / Q000528:radiation effects; D013091:Spermatogenesis / Q000528:radiation effects*; D013737:Testis / Q000378:metabolism; D013997:Time Factors; D014965:X-Rays; D000097642:GADD45 Proteins
D056746:Cyclin G; D056766:Cyclin G1; D016213:Cyclins; D004317:Doxorubicin; D005047:Etoposide; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; D016283:Proto-Oncogene Proteins p21(ras); D012313:RNA; D012333:RNA, Messenger; D000097642:GADD45 Proteins; C534704:Ccng1 protein, rat