Expression and regulation of interferon-gamma-inducible protein 10 gene in rat Leydig cells.
In the present study, we report the cloning of a gene that is differentially expressed in normal adult rat Leydig cells and whose expression is inhibited by hCG but is induced by interferon-gamma (IFNgamma). DNA sequence analysis identified this gene as rat IFNgamma-inducible protein 10 (IP-10), a member of the -C-X-C- chemokine superfamily of proinflammatory cytokines. High levels of IP-10 messenger RNA (mRNA) were constitutively expressed in freshly isolated and primary cultured Leydig cells. hCG inhibited this expression in a dose-dependent manner. The addition of 1 ng/ml hCG inhibited IP-10 mRNA levels more than 80%. Conversely, IP-10 mRNA levels were markedly increased in response to murine interleukin-1alpha, murine tumor necrosis factor-alpha, and murine IFNgamma by 3.3-, 10-, and 26-fold, respectively. Concomitant addition of murine interleukin-1alpha, murine tumor necrosis factor-alpha, and murine IFNgamma synergistically increased IP-10 mRNA levels by 58-fold. Furthermore, in addition to one previously described rat IP-10 mRNA transcript (1.5 kb), another larger transcript (2.7 kb) was identified by Northern blot in rat Leydig cells. After screening a rat testis complementary DNA library, we obtained a partial structural gene and an intron sequence, which possibly originated from the larger transcript of rat IP-10 mRNA. Histochemical and immunocytochemical staining revealed that purified cells were positive for 3beta-hydroxysteroid dehydrogenase and IP-10, confirming that IP-10 is indeed present in Leydig cells. IP-10 antisense oligonucleotides enhanced basal and hCG-induced testosterone formation. This suggests that endogenous IP-10 has an inhibitory effect on Leydig cell steroidogenesis. In conclusion, IP-10 is expressed in rat Leydig cells and may have paracrine and autocrine effects on testicular function.
Hu
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J
Research and Medical Service, WJB Dorn Veterans Medical Center, University of South Carolina School of Medicine, Columbia 29208, USA.
You
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Li
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Wang
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Nagpal
M L
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Mi
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Liang
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Lin
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D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002478:Cells, Cultured; D054357:Chemokine CXCL10; D019743:Chemokines, CXC / Q000235:genetics* / Q000494:pharmacology; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D018076:DNA, Complementary / Q000032:analysis / Q000737:chemistry; D005786:Gene Expression Regulation / Q000187:drug effects; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D007985:Leydig Cells / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013737:Testis / Q000737:chemistry; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D054357:Chemokine CXCL10; D019743:Chemokines, CXC; D006063:Chorionic Gonadotropin; D018076:DNA, Complementary; D007375:Interleukin-1; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma