Reproductive actions of prolactin mediated through short and long receptor isoforms

Prolactin (PRL) is a polypeptide hormone with a wide range of physiological functions, and is critical for female reproduction. PRL exerts its action by binding to membrane bound receptor isoforms broadly classified as the long form and the short form receptors. Both receptor isoforms are highly expressed in the ovary as well as in the uterus. Although signaling through the long form is believed to be more predominant, it remains unclear whether activation of this isoform alone is sufficient to support reproductive functions or whether both types of receptor are required. The generation of transgenic mice selectively expressing either the short or the long form of PRL receptor has provided insight into the differential signaling mechanisms and physiological functions of these receptors. This review describes the essential finding that both long and short receptor isoforms are crucial for ovarian functions and female fertility, and highlights novel mechanisms of action for these receptors.     

Identification and sequence analysis of prolactin receptor and its differential expression profile at various developmental stages in striped hamsters

Prolactin (PRL) plays critical roles in regulation of biological functions with the binding of specific prolactin receptor (PRLR). Revealing the expression patterns of PRLR at different developmental stages is beneficial to better understand the role of PRL and its mechanism of action in striped hamsters. In this study, the cDNA sequence of PRLR (2866-base-pairs) was harvested from the pituitary of mature female striped hamsters (Cricetulus barabensis) that contains an 834-base-pair 5′-untranslated region (1-834 bp), a 1848-base-pair open reading frame (835-2682 bp), and a 184-base-pair 3′-untranslated region (2683-2866). The 1848-base-pair open reading frame encodes a mature prolactin-binding protein of 592 amino acids. In the mature PRLR, two prolactin-binding motifs, 12 cysteines, and five potential Asn-linked glycosylation sites were detected. Our results showed that the PRLR mRNA quantity in the hypothalamus, pituitary, ovaries, or testis was developmental-stage-dependent, with the highest level at sub-adult stage and the lowest level at old stage. We also found that PRLR mRNAs were highest in pituitary, medium level in hypothalamus, and lowest in ovaries or testis. PRLR mRNAs were significantly higher in males than in females, except in the hypothalamus and pituitary from 7-week-old striped hamsters. Moreover, the PRLR mRNAs in the hypothalamus, pituitary, and ovaries or testis were positively correlated with the expression levels of GnRH in the hypothalamus. These results indicated that the PRLR has conserved domain in striped hamster, but also possesses specific character. PRLR has multiple biological functions including positively regulating reproduction in the striped hamster.     

补肾益气清热方对溴隐亭致低PRL大鼠流产模型蜕膜PRLR、PR、ER mRNA的影响

目的 :从基因转录水平探讨补肾益气清热中药对溴隐亭致低 PRL流产大鼠模型的 PRLR、PR、ER m RNA在蜕膜上表达的影响 ,同时观察血中 PRL、P、E2 的动态变化。方法 :采用 RT- PCR方法行半定量图像分析 ,观察溴隐亭致低 PRL流产大鼠模型组 ( A组 )与模型 +中药保胎组 ( A+ H组 )之间 PRLR、PR、ER m RNA表达的差异 ;放免法测定血清 PRL、P、E2 的水平。结果 :A组蜕膜PRLR、PR m RNA表达明显低于 A+ H组 ( P<0 .0 1 ) ,ER m RNA表达两组间无显著性差异 ( P>0 .0 5 ) ;A组流产率为 67% ,而 A+ H组流产率仅为 1 7% ,差异有显著性 ;A组孕 7～ 1 0 d血清PRL、P水平显著低于 A+ H组 ( P<0 .0 5 )。结论 :溴隐亭可导致血清 PRL、P水平下降 ,且下调早孕大鼠蜕膜 PRLR、PR m RNA的表达而导致流产发生 ,补肾益气清热方可能通过促进 PRL、P分泌 ,上调 PRLR、PR m RNA的表达 ,恢复正常的妊娠微环境而起到保胎作用。     

催乳素受体基因多态性对西藏小型猪繁殖性能的影响

目的了解催乳素受体（PRLR）基因AIuI位点在西藏小型猪中的多态性分布情况;研究其在西藏小型猪上的遗传效应,为生长繁殖性状的分子遗传标记辅助选择提供实验依据。方法收集44头西藏小型猪母猪窝产仔数及离乳仔数数据,测定所产仔猪的初生重和离乳重,采用PCR-RFLP方法测定PRLR基因AIuI位点多态性,并与上述生长繁殖性能指标进行相关性分析。结果西藏小型猪PRLR侯选基因AIuI位点表现出多态性,分为AA、AB、BB,频率分别为0.273、0.500、0.227。经产母猪的仔猪初生重在不同基因型间存在显著性差异,而初产和经产母猪的其他生长繁殖指标在不同基因型间均未达到显著性水平。结论本研究中PRLR基因AIuI位点多态性AA、AB、BB不同基因型之间窝产仔数和离乳仔数差异不显著。     

Prolactin-induced activation of phagocyte NADPH oxidase in the teleost fish gilthead seabream involves the phosphorylation of p47phox by protein kinase C

The pituitary hormone prolactin (PRL) is a multifunctional polypeptide which act as a key component of the neuroendocrine-immune loop and as a local regulator of the macrophage response. The involvement of PRL in regulating monocyte/macrophage functions is suggested by the presence of PRL receptors in these cells. Recently, we reported that physiological concentrations of native PRL were able to induce the expression of the pro-inflammatory cytokines IL-1β and TNFα, and the production of reactive oxygen species (ROS) in head kidney leukocytes and macrophages from the teleost fish gilthead seabream (Sparus aurata L.). In this study, we show that the NADPH oxidase subunit p47phox becomes phosphorylated in leukocytes stimulated with PRL, an effect that is blocked when neutralizing polyclonal antibodies to PRL are added. Additionally, the pharmacological inhibition of either protein kinase C (PKC) with calphostin C or the Jak/Stat signaling pathway with AG490 impaired PKC activation, p47phox phosphorylation and ROS production in seabream leukocytes activated with PRL. Taken together, our results demonstrate for the first time the need for PKC in regulating the PRL-mediated phosphorylation of p47phox, the activation of NADPH oxidase and the production of ROS by macrophages in vertebrates.     

Prolactin stimulates cell migration and invasion by human trophoblast in vitro

Introduction

Prolactin (PRL) is present in endometrium at the time of embryo implantation and throughout pregnancy. Extrapituitary PRL acts as a cytokine in cells expressing PRL receptor (PRLR). So far no specific function has been demonstrated for PRL in the trophoblast of early pregnancy.

Methods

PRLR in placental tissue and trophoblast cells was shown here immunochemically. The possibility that PRL could influence trophoblast cell migration and invasion was investigated in vitro using isolated cytotrophoblast of the first trimester of pregnancy placental tissue and HTR-8/SVneo cell line. Wound healing cell migration test was performed on HTR-8/SVneo cells, and both cell types were used in Matrigel invasion test.

Results

PRLR is expressed by extravillous cytotrophoblast of the cell column and the placental bed, as well as in isolated cytotrophoblast (CT) and HTR-8/SVneo cells. PRL (at 100 and 1000 ng/ml) stimulated HTR-8/SVneo cell migration and cell invasion in both cell types, which could be blocked by anti-PRLR. Integrins α1 and α5, and galectin-1 (gal-1) were variably increased in PRL treated CT and HTR-8/SVneo cells.

Discussion

To our knowledge this is the first study demonstrating that PRL stimulates trophoblast invasiveness through PRLR, which is accompanied by increased integrins and gal-1, not excluding change in other potential mediators. This finding further supports relevance of PRLR for invasive trophoblast.

Conclusion

This report supports a possibility that PRL may have a role in trophoblast invasion in vivo.     

PRLR基因反义RNA对人乳腺癌细胞系MCF-7增殖的影响

目的:构建表达人催乳素受体基因(prolactin receptor,PRLR)反义RNA的真核表达质粒,观察其对乳腺癌细胞MCF-7增殖的影响.方法:应用基因重组技术,将人PRLR的cDNA反向克隆至pcDAN3.1(-)载体中,构建PRLR反义RNA真核表达质粒,将其转染人人乳腺癌细胞系MCF-7中,经G418筛选得到稳定细胞克隆,利用荧光定量PCR检测转染后细胞PRLR基因表达量的变化,应用MTT法、平板克隆形成实验及流式细胞术评价转染后细胞的增殖情况.结果:成功构建出能够表达PRLR反义RNA的真核表达质粒,转染该质粒后,MCF-7中PRLR基因表达量下降,细胞生长变慢,克隆形成能力降低,G1期细胞增加,S期细胞减少.结论:PRLR反义RNA能够下调该基因的表达,并且抑制乳腺癌细胞的增殖,证明反义基因干预治疗的可能性,为乳腺癌基因治疗的进一步研究提供了必要的依据.