|Budget Amount *help
¥6,100,000 (Direct Cost : ¥6,100,000)
Fiscal Year 1994 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1993 : ¥2,400,000 (Direct Cost : ¥2,400,000)
Fiscal Year 1992 : ¥2,700,000 (Direct Cost : ¥2,700,000)
SRY-related cDNA encoding a protein with an HMG box and a leucine zipper motif, designated SOX-LZ,was isolated from a rainbow trout testis cDNA library. Its comparison with the mouse homologous cDNA isolated from a testis cDNA library exhibits an overall amino acid sequence identity of 77%, which is a striking contrast to the abrupt loss of amino acid sequence homology outside the HMG found among mammalian SRY genes. In both rainbow trout and mouse, Northern blot analyzes have revealed the presence of a trstis-specific 3 kb-long SOX-LZ mRNA,and this transcript appeared coincidently with the protamine mRNA,suggesting its expression in the germ line. Recombinant HMG box region protein of SOX-LZ could bind strongly with an oligonucleotide containing an AACAAT sequence, which is also recognized by mouse SRY and Sox-5. Upon cotransfection into CHO cells, SOX-LZ transactivated transcription through its binding motif was deleted (DELTASOX-LZ). The intact SOX-LZ could form homodimers, but retained much weaker DNA binding activity by the HMG box than DELTASOX-LZ which was incapable of dimerization. Thus, the repressed transactivation of the intact SOX-LZ in CHO cells was at least partiey attributable to the low DNA binding of SOX-LZ homodimers. Taken together, these data suggest that SOX-LZ plays a role in spermatogenesis as a transcriptional regulator.
We also have isolated three types of SRY-related cDNAs (SOX-OvA,OvB,and OvC) from ovary cDNA library and one type (SOX-P1) from pituitary cDNA library of the immature rainbow trout. Northern blot analyzes have shown that SOX-OvA,OvB,and OvC mRNAs were more abundunt in ovarian tissues than other tissues. The expression of SOX-P1 gene was much higer in pituitaries of immature trout than mature trout, suggesting a role of development or sexual differentiation of pituitaries.