Developmental aspects of prolactin receptor gene expression in fetal and neonatal mice

Abstract

The prolactin receptor (PRL-R), a member of the hematopoietin cytokine receptor superfamily, is widely distributed among mammalian tissues. To understand better the potential sites of action and onset of potential PRL responsiveness, the developmental distribution pattern of PRL-R mRNA expression in fetal and neonatal mice was examined. Fetal mouse tissues were collected at distinct stages from timed pregnancies. Following extraction of total RNA, onset of gene expression was evaluated via reverse transcription-polymerase chain reaction (RT-PCR) and Southern hybridization was employed for verification. Expression of PRL-R mRNA was first observed on day 14 in the liver and cranium and on day 15 in the kidney, lung and thymus gland. Pituitary and adrenal glands were positive for PRL-R at day 18 of gestation through to day 1 of postnatal life. Neither whole fetuses prior to day 14 (days 10-13) of gestation nor skin and bladder tissues from 2-day-old mice generated detectable RT-PCR signals for PRL-R. The presence of PRL-R mRNA in fetal thymus and spleen tissues suggests a possible role for PRL in the development of the immune system. Prolactin may act directly on the pituitary to influence its own secretion and/or that of other pituitary-derived factors, as evidenced by the presence of PRL-R mRNA in the pituitary glands of fetal and 1-day-old mice. These data are the first to show the presence of PRL-R gene expression in various organ systems in fetal mice and suggest that PRL is among several factors necessary to coordinate developmental activities.

Prolactin Binding Analysis and Immunohistochemical Localization of Prolactin Receptor in Porcine Ovarian Cells.

“…First appearance of PRL binding was seen in Tc of medium follicles (Bmax = 0.97 ± 0.052, n = 5) , in Tc of large follicle (1.573 ± 0.45, n=7) and in ECL cells (1.7 ±0.14, N=8) which contained the largest number of PRL-R. Discussion PRL binding to ovaries was reported in rat [17,33], hamster [16] mouse [19] and human [20]. Magoffin and Erickson [18,34] demonstrated specific high affinity PRL-Rs in cultured interstitial cells of the rat ovary.…”

Administration of unmodified prolactin (U-PRL) and a molecular mimic of phosphorylated prolactin (PP-PRL) during rat pregnancy provides evidence that the U-PRL:PP-PRL ratio is crucial to the normal development of pup tissues

“…The present study has demonstrated that changes in the ratio of unmodified to phosphorylated PRL in the maternal circulation, produced via administration of recombinant unmodified PRL (U-PRL) or pseudophosphorylated PRL (PP-PRL) have a marked influence on the development of a number of fetal tissues; tissues previously shown by others to express high levels of PRL receptors (Royster et al 1995, Brown-Borg et al 1996, Tzeng & Linzer 1997.…”

“…Fetal thymocytes also express the PRL receptor , Royster et al 1995, Brown-Borg et al 1996. In the PP-PRL-exposed pups, the thymus contained abundant apoptotic thymocytes.…”

Identification of Prolactin Synthesis at Early Differentiation Stage of T Cells in the Thymus

“…Moreover, PRL receptors have been detected on thymic epithelial cells [8], which may be a direct paracrine target of thymic produced PRL. Recent studies have shown that about 70% of T cells express PRL receptors [3,11,12,14,25]. These findings suggest that PRL may also act as a local cytokine in an autocrine fashion as well.…”