Article

Characterization of a testicular 17alpha, 20beta-dihydroxy-4-pregnen-3-one (a spermiation-inducing steroid in fish) receptor from a teleost, Japanese eel (Anguilla japonica).

Laboratory of Reproductive Biology, National Institute for Basic Biology, Okazaki, Japan.
FEBS Letters (Impact Factor: 3.58). 02/2000; 465(1):12-7. DOI: 10.1016/S0014-5793(99)01714-7
Source: PubMed

ABSTRACT A cDNA encoding a nuclear 17alpha,20beta-dihydroxy-4-pregnen-3-one (17alpha,20beta-DP, spermiation-inducing hormone in fish) receptor (DPR) was, for the first time, isolated from an eel testis cDNA library. The amino acid sequence of DPR shows high homology with those of human and chicken progesterone receptors. The affinity of the bacterial recombinant DPR ligand binding domain protein for 17alpha,20beta-DP is higher than that of progesterone. In transfection experiments using COS7 cells, the DPR showed progestin-dependent activation of transcription. 17alpha,20beta-DP was the most effective activator of transcription. These results indicate that the cDNA encodes a functional eel DPR, and show that 17alpha,20beta-DP has a nuclear receptor-mediated action in eel testes.

0 Bookmarks
 · 
60 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The transactivational property of natural and synthetic chemicals via medaka vitamin D receptor β subtype (VDRβ) was investigated after the development of a stable cell line expressing a Gal4-VDRβ fusion protein for reporter gene assay. Members of vitamin D class, including 1α, 25- dihydroxyvitamin D3 (1,25VD3) were specifically detected as agonists in our system. Although other steroids and chemicals used in the present estimation induced no agonistic response, 10 compounds displayed antagonistic or synergistic activity. Spironolactone, which is an antagonist of corticoid receptors in mammals, competitively inhibited the transactivity of 1,25VD3 by over 80% in a dosedependent manner. Mifepristone and cyproterone acetate were also detected as antagonists, but they significantly acted only at 10µ. Pregnenolone and raloxifene dose-dependently enhanced the activity of 1,25VD3 at EC50 to the maximum level. Diethylstilbestrol, 17α-ethynylestradiol, genistein, and stanozolol were also synergists, but their potency was low. Interestingly, dibutyltin dichloride, which is used as a stabilizer in the production of polyvinyl chloride plastics, produced greater response than maximum effect of 1,25VD3 although the concentration-response curve was not typically sigmoidal. In the present study, we successfully developed a stable reporter gene assay, which allows assessment of the vitamin D-like chemicals toward the medaka VDRβ.
    ZOOLOGICAL SCIENCE 04/2014; 31(4):195-201. · 1.08 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In vitro studies indicated that maturation inducing hormone, 17α, 20β-Dihydroxy-4-pregnen-3-one (DHP), probably through nuclear progestin receptor (Pgr), might be involved in spermatogonia proliferation and meiotic initiation in several fish species. However, it is necessary to provide further in vivo evidences to elucidate DHP actions in spermatogenesis during sexual differentiation in teleosts. In this study, we cloned and analyzed the expression of pgr in Nile tilapia (Oreochromis niloticus), and performed RU486 (synthetic Pgr antagonist) treatment in XY fish from 5 day after hatching (dah). Sequences and phylogenetic analysis revealed that it is a genuine Pgr. Tilapia Pgr was expressed in the Sertoli cells surrounding spermatogonia and spermatids. Real-time PCR analysis demonstrated that pgr expression was significantly up-regulated from 10dah, further increased at 50dah and persisted till adulthood in testes. In RU486-treated testes, transcript levels of germ cell markers and meiotic marker were substantially reduced. However, the expression of Sertoli cell markers remained unchanged. Moreover, 11-KT production and expression of various steroidogenic genes were also not altered. On the contrary, cyp17a2, encoding one of the critical steroidogenic enzymes for DHP biosynthesis, significantly declined suggesting a possible inhibition of DHP production by RU486 treatment. Spermatogenesis was unaffected with RU486 treatment for two months, however, treatment exceeding three months resulted in the decrease of spermatogonia numbers and absence of later phase spermatogenic cells. Simultaneous excessive DHP supplementation restored spermatogenesis in RU486-treated testis. Taken together, our data further proved that DHP, possibly through Pgr, might be essential in the spermatogonia proliferation and spermatogenesis in fish.
    Journal of Molecular Endocrinology 05/2014; · 3.58 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this study, although the highest production of two physiologically significant progestins in teleosts [17,20β-dihydroxypregn-4-en-3-one (17,20β-P) and 17,20β,21-trihydroxypregn-4-en-3-one (17,20β,21-P)] was observed in the period just prior to spawning in both male and female roach Rutilus rutilus, there was also a substantial production (mean levels of 5-10 ng ml(-1) in blood; and a rate of release of 5-20 ng fish(-1) h(-1) into the water) in males and females in the late summer and early autumn (at least 7 months prior to spawning). During this period, the ovaries were increasing rapidly in size and histological sections were dominated by oocytes in the secondary growth phase [i.e. incorporation of vitellogenin (VTG)]. At the same time, the testes were also increasing rapidly in size and histological sections were dominated by cysts containing mainly spermatogonia type B. Measurements were also made of 11-ketotestosterone (11-KT) in males and 17β-oestradiol and VTG in females. The 3 months with the highest production of 11-KT coincided with the period that spermatozoa were present in the testes. In females, the first sign of a rise in 17β-oestradiol concentrations coincided with the time of the first appearance of yolk globules in the oocytes (in August). The role of the progestins during the late summer and autumn has not been established.
    Journal of Fish Biology 08/2013; 83(2):233-49. · 1.83 Impact Factor

Full-text

Download
0 Downloads
Available from