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ATP secretion in the male reproductive tract: essential role of CFTR

Authors

  • Ye Chun Ruan,

    1. Center for Systems Biology/Program in Membrane Biology/Nephrology Division, Massachusetts General Hospital/Harvard Medical School, Boston, MA 02114, USA
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  • Winnie W. C. Shum,

    1. Center for Systems Biology/Program in Membrane Biology/Nephrology Division, Massachusetts General Hospital/Harvard Medical School, Boston, MA 02114, USA
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  • Clémence Belleannée,

    1. Center for Systems Biology/Program in Membrane Biology/Nephrology Division, Massachusetts General Hospital/Harvard Medical School, Boston, MA 02114, USA
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  • Nicolas Da Silva,

    1. Center for Systems Biology/Program in Membrane Biology/Nephrology Division, Massachusetts General Hospital/Harvard Medical School, Boston, MA 02114, USA
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  • Sylvie Breton

    1. Center for Systems Biology/Program in Membrane Biology/Nephrology Division, Massachusetts General Hospital/Harvard Medical School, Boston, MA 02114, USA
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S. Breton: Massachusetts General Hospital, Program in Membrane Biology, Simches Building, 185 Cambridge Street, Suite 8.204, Boston, MA 02114, USA.  Email: sbreton@partners.org

Key points

  • CFTR is expressed in principal cells but not clear cells in mouse cauda epididymis.

  • Inhibition or knockdown of CFTR inhibits ATP release from mouse epididymal principal cells.

  • Inhibition of CFTR reduces ATP release into the lumen of cauda epididymis in mice in vivo.

  • These results show the involvement of CFTR in the regulation of ATP release from epithelial principal cells in the cauda epididymidis.

  • Defective ATP signalling in the epididymis might contribute to dysfunction of the male reproductive tract associated with CFTR mutations.

Abstract  Extracellular ATP is essential for the function of the epididymis and spermatozoa, but ATP release in the epididymis remains uncharacterized. We investigated here whether epithelial cells release ATP into the lumen of the epididymis, and we examined the role of the cystic fibrosis transmembrane conductance regulator (CFTR), a Cl and HCO3 conducting ion channel known to be associated with male fertility, in this process. Immunofluorescence labelling of mouse cauda epididymidis showed expression of CFTR in principal cells but not in other epithelial cells. CFTR mRNA was not detectable in clear cells isolated by fluorescence-activated cell sorting (FACS) from B1-EGFP mice, which express enhanced green fluorescent protein (EGFP) exclusively in these cells in the epididymis. ATP release was detected from the mouse epididymal principal cell line (DC2) and increased by adrenaline and forskolin. Inhibition of CFTR with CFTRinh172 and transfection with CFTR-specific siRNAs in DC2 cells reduced basal and forskolin-activated ATP release. CFTR-dependent ATP release was also observed in primary cultures of mouse epididymal epithelial cells. In addition, steady-state ATP release was detected in vivo in mice, by measuring ATP concentration in a solution perfused through the lumen of the cauda epididymidis tubule and collected by cannulation of the vas deferens. Luminal CFTRinh172 reduced the ATP concentration detected in the perfusate. This study shows that CFTR is involved in the regulation of ATP release from principal cells in the cauda epididymidis. Given that mutations in CFTR are a leading cause of male infertility, we propose that defective ATP signalling in the epididymis might contribute to dysfunction of the male reproductive tract associated with these mutations.

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