BACKGROUND: Prolactin (PRL), originally identified as an anterior pituitary hormone exhibiting lactogenic activity, is now recognized as a versatile hormone expressed in a wide variety of tissues. METHODS: In this study, the expression of PRL in the mouse kidney was investigated by solution-phase and in situ reverse transcription-polymerase chain reaction (RT-PCR) methods and immunohistochemistry. RESULTS: Mouse PRL (mPRL) transcript and protein are localized in the parietal epithelial cells of Bowman's capsule. Pit-1 is a positive transcription factor for the expression of the PRL gene. The presence of Pit-1 transcript in the kidney was also assessed by RT-PCR methods. The localization of Pit-1 mRNA coincided well with that of PRL. Immunoreactivity to mouse PRL receptor (mPRL-R) is distributed on the luminal membrane of the proximal tubule cells and the parietal epithelial cells of Bowman's capsule. CONCLUSION: These data indicate that the parietal epithelial cells of Bowman's capsule synthesize PRL de novo and suggest that Pit-1 contributes to the transcriptional regulation of PRL gene expression in the kidney, and PRL expressed in this tissue functions in an autocrine/paracrine fashion.
BACKGROUND:Prolactin (PRL), originally identified as an anterior pituitary hormone exhibiting lactogenic activity, is now recognized as a versatile hormone expressed in a wide variety of tissues. METHODS: In this study, the expression of PRL in the mouse kidney was investigated by solution-phase and in situ reverse transcription-polymerase chain reaction (RT-PCR) methods and immunohistochemistry. RESULTS:MousePRL (mPRL) transcript and protein are localized in the parietal epithelial cells of Bowman's capsule. Pit-1 is a positive transcription factor for the expression of the PRL gene. The presence of Pit-1 transcript in the kidney was also assessed by RT-PCR methods. The localization of Pit-1 mRNA coincided well with that of PRL. Immunoreactivity to mousePRL receptor (mPRL-R) is distributed on the luminal membrane of the proximal tubule cells and the parietal epithelial cells of Bowman's capsule. CONCLUSION: These data indicate that the parietal epithelial cells of Bowman's capsule synthesize PRL de novo and suggest that Pit-1 contributes to the transcriptional regulation of PRL gene expression in the kidney, and PRL expressed in this tissue functions in an autocrine/paracrine fashion.