MOLECULAR REPRODUCTION AND DEVELOPMENT 71:444–452 (2005) Localization of Transient Receptor Potential Ion Channels in Primary and Motile Cilia of the Female Murine Reproductive Organs STEFAN C. TEILMANN, 1 ANNE GRETE BYSKOV, 1 PER A. PEDERSEN, 2 DENYS N. WHEATLEY, 3 GREGORY J. PAZOUR, 4 AND SØREN T. CHRISTENSEN 5 * 1 Laboratory of Reproductive Biology, Rigshospitalet, Denmark 2 Institute for Molecular Biology and Physiology, The August Krogh Building, Laboratory of Cellular and Molecular Physiology, University of Copenhagen, Denmark 3 BioMedES, Leggat House, Keithhall, Inverurie, Aberdeen, Scotland, United Kingdom 4 University of Massachusetts Medical School, Worcester, Massachusetts 5 Institute for Molecular Biology and Physiology, The August Krogh Building, Department of Biochemistry, University of Copenhagen, Denmark ABSTRACT We have examined the subcellu- lar localization of transient receptor potential (TRP) ion channels and the potential sensory role of cilia in murine female reproductive organs using confocal laser scanning microscopy analysis on ovary and oviduct tissue sections as well as on primary cultures of fol- licular granulosa cells. We show that the Ca 2þ permeable cation channel, polycystin-2, as well as polycystin-1, a receptor that forms a functional protein complex with polycystin 2, distinctively localize to primary cilia emerging from granulosa cells of antral follicles in vivo and in vitro. Both polycystins are localized to motile oviduct cilia and this localization is greatly increased upon ovulatory gonadotropic stimula- tion. Further, the Ca 2þ permeable cation channel, TRP vaniloid 4 (TRPV4), localizes to a sub-population of motile cilia on the epithelial cells of the ampulla and isthmus with high intensity in proximal invaginations of the epithelial folds. These observations are the first to demonstrate ciliary localization of TRP ion channels and their possible receptor function in the female reproductive organs. We suggest that polycystins 1 and 2 play an important role in granulosa cell differentiation and in development and maturation of ovarian fol- licles. In the oviduct both TRPV4 and polycystins could be important in relaying physiochemical changes in the oviduct upon ovulation. Mol. Reprod. Dev. 71: 444–452, 2005. ß 2005 Wiley-Liss, Inc. Key Words: ovary; granulosa cells; oviduct; cilia; polycystin; TRPV4; reproduction INTRODUCTION In the mouse, the ovary and oviduct operate as highly coordinated functional unit with the purpose of follicu- logenesis, delivery of cumulus – oocyte complexes (COC) to the oviduct by ovulation, and transporting the devel- oping blastocysts to the uterus for implantation. These processes are regulated by cellular and endocrine signaling events beginning with the growth and matu- ration of the follicle, in which granulosa cells play a supportive role in oocyte maturation and are involved in ovulation and luteinization. During follicular growth, granulosa cells undergo massive proliferative and differential changes mediated by a variety of hormones and growth factors (Matzuk et al., 2002). At some point the gonadotropic hormones FSH and LH and the steroid hormone estradiol, drives the formation of a large fluid filled cavity or ‘‘antrum’’ within the follicle, expanding follicle volume dramatically (Byskov, 1969). Although the exact function of the antrum is not yet clear, follicle fluid contains—besides high concentrations of ster- oids—factors that are necessary for oocyte maturation and fertilization (Odum et al., 2002). The cranical segment of the oviduct, the infundibulum, is lined by a ciliated epithelium that, by ciliary beating, helps to provide the motive force necessary for COC pickup and transport (Talbot et al., 1999). Soon after ovulation fluid accumulates around the COCs and dilates the otherwise narrow oviductal tract as the ovulated COCs moves towards ampulla, the site of fertilization (Croxatto, 2002). The establishment of a suitable environment for COC transport after adhesion to the ciliated infundibu- lum and priming of the ampulla for reception and fertilization of the oocytes are regulated through a series of physiochemical changes. These include changes in ionic composition and osmolarity of the oviduct fluid (Gandolfi, 1995) and rises in temperature, which ß 2005 WILEY-LISS, INC. Grant sponsor: The Danish Research Council, The NOVO Foundation; Grant sponsor: ‘‘Fonden af 1870’’ (to STC); Grant sponsor: EU project QLRT-2000-00305 (to AGB). *Correspondence to: Søren T. Christensen, Department of Biochem- istry, The August Krogh Institute, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen, Denmark. E-mail: stchristensen@aki.ku.dk Received 22 October 2004; Accepted 14 December 2004 Published online 27 April 2005 in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mrd.20312