Dusanter-Fourt I, Belair L, Gespach C, Djiane J
Unité d'Endocrinologie Moléculaire, Institut National de la Recherche Agronomique, Jouy-en-Josas, France.
Endocrinology. 1992 May;130(5):2877-82. doi: 10.1210/endo.130.5.1572300.
Specific binding sites for PRL were identified on isolated intestinal epithelial cells from both male and female rabbits. These receptors exhibited a very high affinity for PRL (Kd = 5 x 10(-11) M) and were immunologically very similar to the well characterized mammary PRL receptor. About 3500 PRL receptors/cell were expressed on isolated epithelial cells from rabbit jejunum. These receptors were distributed in precise portions of the gut, being highly expressed in the proximal small intestine (duodenum and jejunum), moderately expressed in the ileum, and barely detectable in the colon. The levels of intestinal epithelial PRL receptors were low in 15-day-old rabbits, moderate at 1 month, and reached adult levels at 2 months, indicating enhanced PRL receptor expression in the intestine as development proceeded. The PRL receptor gene was specifically and highly expressed in the rabbit intestine, and four PRL receptor transcripts were detected that were identical to the transcripts characterized in the mammary gland. In individual intestinal segments, the expression of PRL-binding sites was always highly correlated with the level of PRL receptor mRNA. These results show that isolated intestinal epithelial cells express the PRL receptor gene as well as specific binding sites with a high affinity for PRL. They suggest that PRL regulates intestinal functions by exerting direct actions on the intestinal epithelial cells.
在雄性和雌性兔的离体肠上皮细胞上均鉴定出了催乳素（PRL）的特异性结合位点。这些受体对PRL表现出非常高的亲和力（解离常数Kd = 5×10⁻¹¹ M），并且在免疫学上与特征明确的乳腺PRL受体非常相似。兔空肠的离体上皮细胞上每个细胞表达约3500个PRL受体。这些受体分布在肠道的特定部位，在小肠近端（十二指肠和空肠）高度表达，在回肠中度表达，在结肠中几乎检测不到。15日龄兔的肠上皮PRL受体水平较低，1月龄时适中，2月龄时达到成年水平，表明随着发育的进行，肠道中PRL受体的表达增强。PRL受体基因在兔肠道中特异性且高度表达，检测到四种PRL受体转录本，它们与乳腺中鉴定出的转录本相同。在各个肠段中，PRL结合位点的表达始终与PRL受体mRNA的水平高度相关。这些结果表明，离体肠上皮细胞表达PRL受体基因以及对PRL具有高亲和力的特异性结合位点。它们提示PRL通过对肠上皮细胞发挥直接作用来调节肠道功能。
