Mol. Hum. Reprod. Advance Access originally published online on November 26, 2008
Molecular Human Reproduction 2009 15(1):11-17; doi:10.1093/molehr/gan070
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Identification of WNT/β-CATENIN signaling pathway components in human cumulus cells
1Department of Physiology and Pharmacology, The University of Western Ontario, London, ON, Canada N6A 5C1 2Department of Obstetrics and Gynaecology, The University of Western Ontario, London, ON, Canada N6A 5C1 3Reproductive Endocrinology and Infertility Program, London Health Sciences Centre, 339 Windermere Road, London, ON, Canada N6A 5A5 4Department of Paediatrics, The University of Western Ontario, London, ON, Canada N6A 5C1 5 Children’s Health Research Institute, 800 Commissioners Road East, London, ON, Canada N6C 2V5
6 Correspondence address. Tel: +1-519-661-3132; Fax: +1-519-850-2562; E-mail: gerald.kidder{at}schulich.uwo.ca
Signaling via the conserved WNT/β-CATENIN pathway controls diverse developmental processes. To explore its potential role in the ovary, we investigated the expression of WNTs, frizzled (FZD) receptors and other pathway components in human cumulus cells obtained from oocytes collected for in vitro fertilization. Proteins were detected in cultured cells using immunofluorescence microscopy. Protein–protein interactions were analyzed by means of immunoprecipitation. WNT2, FZD2, FZD3 and FZD9 were identified but WNT1, WNT4 and FZD4 were not detected. WNT2 is co-expressed with FZD2, FZD3 and FZD9. Co-immunoprecipitation using WNT2 antibody demonstrated that WNT2 interacts with both FZD3 and FZD9, but only FZD9 antibody precipitated WNT2. We also identified DVL (disheveled), AXIN, GSK-3β (glycogen synthase kinase-3β) and β-CATENIN. β-CATENIN is concentrated in the plasma membranes. DVL co-localizes with FZD9 and AXIN in the membranes, but GSK-3β has little co-localization with AXIN and β-CATENIN. Interestingly, β-CATENIN is highly co-localized with FZD9 and AXIN. CDH1 (E-cadherin) was also detected in the plasma membranes and cytoplasm, co-localized with β-CATENIN, and CDH1 antibody precipitated β-CATENIN. The results suggest that WNT2 could act through its receptor FZD9 to regulate the β-CATENIN pathway in cumulus cells, recruiting β-CATENIN into plasma membranes and promoting the formation of adherens junctions involving CDH1.
Key words: ovarian follicle/paracrine signaling/folliculogenesis/gene expression/signal transduction
Submitted on September 16, 2008; resubmitted on November 11, 2008; accepted on November 17, 2008.