title: The functional expression of transient receptor potential channels in the mouse endometrium.
abstract: Does mouse endometrial epithelial cells and stromal cells have a similar transient receptor potential (TRP)-channel expression profile and to that found in the human endometrium?
  
  
  
  Mouse endometrial epithelial and stromal cells have a distinct TRP channel expression profile analogous to what has been found in human endometrium, and hence suggests the mouse a good model to investigate the role of TRP channels in reproduction.
  
  
  
  An optimal intercellular communication between epithelial and stromal endometrial cells is crucial for successful reproduction. Members of the TRP family were recently described in the human endometrial stroma; however their functional expression in murine endometrium remains unspecified. Furthermore, epithelial and stromal cells have distinct functions in the reproductive process, implying the possibility for a different expression profile. However, knowledge about the functional expression pattern of TRP channels in either epithelial or stromal cells is not available.
  
  
  
  In this study, the expression pattern of TRP channels in the murine (C57BL/6 J strain) endometrium was investigated and compared to the human expression pattern. Therefore, expression was examined in uterine tissue isolated during the natural estrous cycle (n = 16) or during an induced menstrual cycle using the menstruating mouse model (n = 28). Next, the functional expression of TRP channels was assessed separately in endometrial epithelial and stromal cell populations.
  
  
  
  Quantitative RT-PCR was used to evaluate the relative mRNA expression of TRP channels in murine uterine tissue and cells. To further assess the functional expression in epithelial or stromal cells, primary endometrial cell cultures and Fura2-based calcium-microfluorimetry experiments were performed.
  
  
  
  The expression pattern of TRP channels during the natural estrous cycle or the induced menstrual cycle is analog to what has been shown in human samples. Furthermore, a very distinct expression pattern was observed in epithelial cells compared to stromal cells. Expression of TRPV4, TRPV6 and TRPM6 was significantly higher in epithelial cells whereas TRPV2, TRPC1/4 and TRPC6 were almost exclusively expressed in stromal cells.
  
  
  
  N/A.
  
  
  
  Although relevant mRNA levels are detected for TRPV6 and TRPM6, and TRPM4, lack of selective, available pharmacology restricted functional analysis of these ion channels.
  
  
  
  Successful reproduction, and more specifically embryo implantation, is a dynamic developmental process that integrates many signaling molecules into a precisely orchestrated program. Here, we describe the expression pattern of TRP channels in mouse endometrium that is similar to human tissue and their restricted functionality in either stromal cells or epithelial cells, suggesting a role in the epithelial-stromal crosstalk. These results will be very helpful to identify key players involved in the signaling cascades required for successful embryo implantation. In addition, these results illustrate that mouse endometrium is a valid representative for human endometrium to investigate TRP channels in the field of reproduction.
  
  
  
  The Research Foundation-Flanders (G.0856.13 N to J.V.); the Research Council of the Katholieke Universiteit Leuven (OT/13/113 to J.V. and PF-TRPLe to T.V.); the Planckaert-De Waele fund (to J.V.);  Fonds Wetenschappelijk Onderzoek Belgium (to K.D.C. and A.H.). None of the authors have a conflict of interest.
authors.affiliation: Laboratory of Obstetrics and Experimental Gynaecology, KU Leuven, Herestraat 49 box 611, B-3000 Leuven, Belgium.
authors.forename: Katrien
authors.initials: K
authors.lastname: De Clercq
authors.affiliation: Laboratory of Obstetrics and Experimental Gynaecology, KU Leuven, Herestraat 49 box 611, B-3000 Leuven, Belgium.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Van den Eynde
authors.affiliation: Laboratory of Obstetrics and Experimental Gynaecology, KU Leuven, Herestraat 49 box 611, B-3000 Leuven, Belgium.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Hennes
authors.affiliation: Laboratory of Obstetrics and Experimental Gynaecology, KU Leuven, Herestraat 49 box 611, B-3000 Leuven, Belgium.
authors.forename: Rieta
authors.initials: R
authors.lastname: Van Bree
authors.affiliation: Laboratory of Ion Channel Research and TRP Research Platform Leuven (TRPLe), KU Leuven, Herestraat 49 box 802, B-3000 Leuven, Belgium.
authors.forename: Thomas
authors.initials: T
authors.lastname: Voets
authors.affiliation: Laboratory of Obstetrics and Experimental Gynaecology, KU Leuven, Herestraat 49 box 611, B-3000 Leuven, Belgium.
authors.forename: Joris
authors.initials: J
authors.lastname: Vriens
mesh_terms: D000818:Animals; D004717:Endometrium / Q000378:metabolism*; D030762:Estrous Cycle / Q000378:metabolism*; D005260:Female; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D017154:Stromal Cells / Q000378:metabolism; D050051:Transient Receptor Potential Channels / Q000235:genetics / Q000378:metabolism*
chemical_list: D050051:Transient Receptor Potential Channels
keywords: TRP channels; epithelial cells; estrous cycle; menstruating mouse model; mouse endometrium; stromal cells