Bera T K, Hwang S I, Swanson S M, Guzman R C, Edery M, Nandi S
Department of Molecular and Cell Biology, University of California, Berkeley 94720.
Mol Cell Biochem. 1994 Mar 30;132(2):145-9. doi: 10.1007/BF00926923.
The receptors for prolactin (PRLR) are expressed in many tissues including the mammary gland, a classical target tissue for prolactin (PRL), but the cellular localization of expression of the PRLR gene in mammary gland has not yet been identified. PRL is known to up regulate its own receptor. We therefore employed the pituitary isografted mouse as a model to distinguish the cells expressing PRLR since PRL blood levels are known to be constitutively elevated in these animals. Mammary glands of virgin or pituitary isografted mice were analyzed by northern blot or in situ hybridization with a digoxygenin-labeled cRNA probe. Northern analysis revealed the expression of 1.3 kb and 2.5 kb forms of PRLR corroborating the results of various laboratories studying other tissues. PRLR was barely detectable by in situ hybridization in non-isografted mice. Two weeks after pituitary isografting, however, PRLR expression was substantially increased in the epithelial cells of mammary ducts and alveoli. No signal was ever detected in the mammary stromal compartment of either virgin or pituitary-isografted mice. The localization of PRL-responsive cells to the parenchyma of the mammary gland suggests that epithelial cells are the mediators of PRL action and that the transcriptional regulation of PRLR expression by PRL is direct in the epithelial cell.
催乳素受体（PRLR）在包括乳腺在内的许多组织中表达，乳腺是催乳素（PRL）的经典靶组织，但PRLR基因在乳腺中的细胞定位尚未确定。已知PRL可上调其自身受体。因此，我们采用垂体移植小鼠作为模型来区分表达PRLR的细胞，因为已知这些动物的PRL血水平持续升高。通过Northern印迹法或用洋地黄毒苷标记的cRNA探针进行原位杂交分析处女小鼠或垂体移植小鼠的乳腺。Northern分析显示1.3 kb和2.5 kb形式的PRLR的表达，证实了研究其他组织的各个实验室的结果。在未移植的小鼠中，原位杂交几乎检测不到PRLR。然而，垂体移植两周后，乳腺导管和腺泡的上皮细胞中PRLR表达显著增加。在处女小鼠或垂体移植小鼠的乳腺间质区均未检测到信号。PRL反应性细胞定位于乳腺实质表明上皮细胞是PRL作用的介质，并且PRL对PRLR表达的转录调控在上皮细胞中是直接的。
