Androgen regulation of prostatic binding protein messenger RNA studied by using cloned complementary DNA.

The construction of a double-stranded cDNA library using rat prostatic poly(A)RNA and pBR322/kappa 1776 system and the isolation of three prostatic binding protein (PBP) cDNA clones are described. These cDNA clones were characterized and identified by in situ hybridization, mRNA selection-translation and immuno-precipitation as coding for the three subunit components, C1, C2, and C3, of PBP. These clones were used in hybridization experiments with prostatic poly(A)RNA to determine the effect of testosterone on the levels of PBP-mRNA. The results showed that synthesis of these mRNAs varied in response to either androgen withdrawal or replacement. Accumulation of PBP-mRNAs coding for C2 and C3 components occurred 1 hr after androgen administration to castrated rat, whereas the mRNA coding for the C1 component did not appear until 4 hr after androgen replacement. Quantitation of PBP-mRNA sequences in nuclear and polysomal poly(A)RNAs showed that they did not vary coordinately in response to androgen withdrawal. These results indicate differential regulation of PBP genes and suggest possible multiple levels of androgen control of PBP synthesis.