@entity398 receptor gene expression in XXXX mammary gland: structural characterization and regulation.

@entity398 @entity172 @entity440 @entity2036 @entity134 @entity35 @entity25809
The differential, tissue-specific regulation of @entity398 (OT) binding sites allows the neurohypophysial nonapeptide OT to fulfill a dual role: to induce uterine contractions at parturition and to mediate milk ejection during lactation. Whereas uterine OT binding sites are up-regulated prior to parturition and are rapidly down-regulated thereafter, mammary gland OT binding sites gradually increase throughout gestation and remain up-regulated during the ensuing lactation period. Here, we structurally characterized @entity25809 ( @entity25809 ) mRNA in mammary gland and analyzed its expression during gestation and lactation and in response to @entity134 treatment. In mammary gland tissues, we found a 6.7 and a 5.4 kb @entity25809 mRNA species, and both species were further analyzed by RACE (rapid amplification of cDNA ends). The 6.7 kb mRNA was found to be common to mammary gland and uterus and to extend 618 @entity2036 beyond the published sequence of the @entity35 @entity25809 gene. The 5.4 kb mRNA species is unique to the mammary gland and terminates at a mammary gland-specific polyadenylation site that is not preceded by a classical polyadenylation signal. RT-PCR analysis did not provide any evidence for differences in the coding regions, suggesting that both uterine and mammary gland @entity25809 mRNAs encode the same receptor protein. Furthermore, primer extension experiments showed that no differences exist in the specific transcriptional initiation sites of the @entity25809 gene in the two tissues. During pregnancy, @entity25809 mRNA per mammary gland increased approximately 150-fold and remained high during lactation, consistent with the previously identified regulation of OT binding sites and the role of OT during lactation. Whereas @entity172 administration strongly induced the uterine @entity25809 mRNA levels (>5-fold), mammary gland remained unaffected by @entity134 treatment. Moreover, @entity440 had no effect on the mammary gland @entity25809 mRNA level. In summary, our data demonstrate a differential control of @entity25809 expression in uterus versus mammary gland and a mammary gland-specific @entity25809 mRNA polyadenylation site. However, this differential control apparently does not involve the expression of different receptor genes nor the utilization of tissue-specific transcriptional initiation sites.
