Changes in the cytologic distribution of heparin/heparan sulfate interacting protein/ribosomal protein L29 (HIP/RPL29) during in vivo and in vitro mouse mammary epithelial cell expression and differentiation.
HIP/RPL29 is a small, highly basic, heparin/heparan sulfate interacting protein identical to ribosomal protein L29 and present in most adult epithelia. In the present study, we show that mouse HIP/RPL29 is ubiquitously present in adult mammary epithelia and is significantly increased during pregnancy and lactation. We observed for the first time that HIP/RPL29 intracellular expression and distribution varies, depending on the growth/differentiation state of the luminal epithelium. HIP/RPL29 was detected at low levels in mammary glands of virgin animals, increased markedly during lactation, and was lost again during involution. HIP/RPL29, preferentially found in the expanded cytoplasm of mature epithelial cells secreting milk, is present also in the nucleus of proliferating and differentiating ductal and alveolar elements. We used COMMA-D cells as an in vitro model for mammary-specific differentiation and examined similar intracellular redistribution of HIP/RPL29 associated with functional differentiation. However, no changes in HIP/RPL29 expression levels were detected in response to lactogenic hormones. Finally, the cellular distribution of HIP/RPL29 in both nuclear and cytoplasmic compartments was confirmed by transfecting a normal mammary epithelial cell line, NMuMG, with a fusion protein of HIP/RPL29 and EGFP. Collectively, these data support the idea that HIP/RPL29 plays more than one role during adult mammary gland development.
Kirn-Safran
Catherine B
CB
Department of Biological Sciences, University of Delaware, Newark, Delaware 19716, USA. ckirn@udel.edu
Julian
Joanne
J
Fongemie
Jennifer E
JE
Hoke
David E
DE
Czymmek
Kirk J C
KJ
Carson
Daniel D
DD
D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D002809:Chondroitin Sulfates / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism*; D005260:Female; D049452:Green Fluorescent Proteins; D006133:Growth Substances / Q000378:metabolism; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism; D006801:Humans; D017403:In Situ Hybridization; D007202:Indicators and Reagents / Q000378:metabolism; D007633:Keratins / Q000378:metabolism; D007774:Lactation / Q000502:physiology; D008164:Luminescent Proteins / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D011247:Pregnancy; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012269:Ribosomal Proteins / Q000378:metabolism*
D006133:Growth Substances; D019812:Heparan Sulfate Proteoglycans; D007202:Indicators and Reagents; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D012269:Ribosomal Proteins; C035078:ribosomal protein L29; C071927:perlecan; D049452:Green Fluorescent Proteins; D007633:Keratins; D002809:Chondroitin Sulfates