title: An intelligent nano-antenna: Primary cilium harnesses TRP channels to decode polymodal stimuli.
abstract: The primary cilium is a solitary hair-like organelle on the cell surface that serves as an antenna sensing ever-changing environmental conditions. In this review, we will first recapitulate the molecular basis of the polymodal sensory function of the primary cilia, specifically focusing on transient receptor potential (TRP) channels that accumulate inside the organelle and conduct calcium ions (Ca(2+)). Each subfamily member, namely TRPP2 TRPP3, TRPC1 and TRPV4, is gated by multiple environmental factors, including chemical (receptor ligands, intracellular second messengers such as Ca(2+)), mechanical (fluid shear stress, hypo-osmotic swelling), or physical (temperature, voltage) stimuli. Both activity and heterodimer compositions of the TRP channels may be dynamically regulated for precise tuning to the varying dynamic ranges of the individual input stimuli. We will thus discuss the potential regulation of TRP channels by local second messengers. Despite its reported importance in embryonic patterning and tissue morphogenesis, the precise functional significance of the downstream Ca(2+) signals of the TRP channels remains unknown. We will close our review by featuring recent technological advances in visualizing and analyzing signal transduction inside the primary cilia, together with current perspectives illuminating the functional significance of intraciliary Ca(2+) signals.
authors.affiliation: Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA; Center for Cell Dynamics, Institute for Basic Biomedical Sciences, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA. Electronic address: sphua1@jhmi.edu.
authors.forename: Siew Cheng
authors.initials: SC
authors.lastname: Phua
authors.affiliation: Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA; Center for Cell Dynamics, Institute for Basic Biomedical Sciences, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Yu-Chun
authors.initials: YC
authors.lastname: Lin
authors.affiliation: Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA; Center for Cell Dynamics, Institute for Basic Biomedical Sciences, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA; Precursory Research for Embryonic Science and Technology (PRESTO) Investigator, Japan Science and Technology Agency (JST), Saitama 332-0012, Japan. Electronic address: jctinoue@jhmi.edu.
authors.forename: Takanari
authors.initials: T
authors.lastname: Inoue
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D002462:Cell Membrane / Q000378:metabolism*; D006801:Humans; D050051:Transient Receptor Potential Channels / Q000378:metabolism*
chemical_list: D050051:Transient Receptor Potential Channels; D002118:Calcium
keywords: Cilium-targeted Ca(2+) indicators; Local Ca(2+)signals; Polymodal sensitivity; Primary cilium; TRPC1; TRPP2; TRPP3; TRPV4
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