Targeted expression of the dominant-negative prolactin receptor in the mammary gland of transgenic mice results in impaired lactation.
The F3-short form of the rat PRL receptor (F3-SPRLR) form acts as a dominant negative inhibitor in vitro. We have developed a transgenic mouse model in which the rat F3-SPRLR was expressed in mammary epithelium under the control of the mouse mammary tumor virus promoter. Two lines of mice were characterized and shown to express the transgene in the mammary gland. No developmental abnormalities or differences from wild-type littermates were observed on the basis of size, activity, or fertility. Mice with a low level of transgene expression had a mammary phenotype similar to the wild type. However, mice overexpressing the transgene (levels much higher than those of the endogenous long PRLR transcript) had impaired mammary gland differentiation and lactation. In these mice, whole-mount and histological analyses demonstrated normal ductal development, but severely reduced lobuloalveolar outgrowth. signal transducer and activator of transcription-5 phosphorylation and expression of beta-casein and whey acidic protein gene were decreased. In vivo bromodeoxyuridine incorporation at midpregnancy showed that the reduction in mammary development was not due to an inhibition of ductal growth and side-branching. This model demonstrates for the first time in vivo a function of the SPRLR and a local and targeted effect of PRL on the mammary gland that are essential for its function, but not for its development.
Institut National de la Santé et de la Recherche Médicale, Unité 344, Endocrinologie Moléculaire, Faculté de Médecine Necker, 75730 Paris, France.
Elise
E
Saunier
Fariel
F
Dif
Paul A
PA
Kelly
Marc
M
Edery
D000818:Animals; D002455:Cell Division / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D015870:Gene Expression; D005799:Genes, Dominant; D007775:Lactation Disorders / Q000503:physiopathology*; D008321:Mammary Glands, Animal / Q000166:cytology / Q000254:growth & development / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D008894:Milk Proteins / Q000235:genetics; D010641:Phenotype; D011981:Receptors, Prolactin / Q000235:genetics*; D050799:STAT5 Transcription Factor; D015534:Trans-Activators / Q000378:metabolism; D019076:Transgenes / Q000235:genetics
D004268:DNA-Binding Proteins; D008894:Milk Proteins; D011981:Receptors, Prolactin; D050799:STAT5 Transcription Factor; D015534:Trans-Activators