Caenorhabditis elegans as a Model to Study Renal Development and Disease: Sexy Cilia
Maureen M. Barr
School of Pharmacy, University of Wisconsin Madison, Madison, Wisconsin
Address correspondence to: Dr. Maureen M. Barr, School of Pharmacy, University of Wisconsin at Madison, 777 Highland Avenue, Madison, WI 53705. Phone: 608-265-1174; Fax: 608-262-5345; E-mail: mmbarr{at}pharmacy.wisc.edu
The nematode Caenorhabditis elegans has no kidney per se, yet"the worm" has proved to be an excellent model to study renal-relatedissues, including tubulogenesis of the excretory canal, membranetransport and ion channel function, and human genetic diseasesincluding autosomal dominant polycystic kidney disease (ADPKD).The goal of this review is to explain how C. elegans has providedinsight into cilia development, cilia function, and human cystickidney diseases.
At first glance, worms and kidneys have as little to do witheach other as do Caenorhabditis elegans geneticists and practicingmedical nephrologists. Sydney Brenner’s choice of C. elegansas a model organism has provided a means for studying the genetics,molecular biology, and biochemistry of many human diseases.The Nobel laureate Brenner selected C. elegans because of itssmall size (approximately 1 mm), rapid free-living life cycle(2 to 3 d from egg to adult), hermaphroditism, large brood size(self-fertilizing hermaphrodites produce approximately 300 offspringand approximately 1000 progeny when mated with males), geneticamenability, transparency, and simple cellular complexity (<1000somatic cells).
The constantly expanding C. elegans molecular toolkit includestransgenesis, a completely sequenced genome, green fluorescenceprotein (GFP) to look at gene expression and protein localizationin vivo, primary cell culture, and RNA interference (RNAi) toknockdown gene function. The C. elegans genome project servedas a prototype for other sequencing projects (1). Likewise,C. elegans systematic genome-wide approaches culminating ineffective, public data archiving at WormBase for C. elegansgenome and biology (http://www.wormbase.org) provide an examplefor high-throughput functional genomics in more complex biologicsystems. Forward or classical genetics is aimed at understandinga biologic process and moves from mutant phenotype to gene/proteinidentification. Reverse genetics starts with the knowledge ofgene/protein sequence and moves to function/phenotype. C. elegansis amenable to both approaches, making the worm an attractivemodel system in which to study your favorite gene (2).
Renal cysts are observed in a number of human genetic disorders,suggesting that disrupting any one of a number of differentcellular processes may result in cyst formation. An alternativehypothesis is that for those disorders that share a subset ofrenal and extrarenal manifestations, cysts may arise from disruptionof a conserved cellular function. Autosomal dominant polycystickidney disease (ADPKD), autosomal recessive PKD (ARPKD), nephronophthisis(NPHP), and Bardet-Biedl syndrome (BBS) share two common features:Cystic kidneys and ciliary localized gene products (Table 1)(3,4). "Ciliary cystoproteins" (3) include polycystin-1 (PC-1)and PC-2, which are defective in ADPKD (5–7); fibrocystinor polyductin, which is defective in ARPKD (8–10); nephrocystin-1and nephrocystin-2/inversin, which are defective in nephronophthisis(11,12); and BBS3 and BBS5 through BBS8, which are defectivein BBS (13–16).
Table 1. Mammalian kidney disease genes and C. elegans homologs
Cystic kidney diseases, primary cilia dyskinesia, retinitispigmentosa, and situs inversus (reversal of left-right organasymmetry) are human diseases that result from ciliary defects(17). Establishing and maintaining ciliary function is clearlyessential for the well-being of an organism. Cilia are specializedorganelles that function in motility (9 + 2 motile cilia or9 + 0 nodal cilia) or sensation (9 + 0 primary or sensory cilia).Primary kidney cilia project from the apical surfaces of epithelialcells of the kidney nephron and act as flow mechanosensors (18–20).Nodal cilia are located on the embryonic node, exhibit a uniquerotation, and are necessary to establish left-right (L-R) asymmetryin vertebrates (21). The greatest challenges to both molecularbiologists and nephrologists are determining the mechanismsunderlying renal cystic diseases, understanding their interconnections,and designing therapies to prevent, delay, or halt cyst progression.
All Cilia Are Created Equal: Lessons from Algae and Worms
Intraflagellar transport (IFT) is an evolutionarily conserved,microtubule-based motility that is responsible for the assemblyand maintenance of all cilia and flagella (22). IFT was firstobserved by Rosenbaum and colleagues (23) as microscopic particlesmoving up and down the length of the flagella of the green algaChlamydomonas. The cellular machinery driving IFT was determinedusing primarily cellular and biochemical approaches (see referenceswithin 22). The IFT machinery comprises heterotrimeric kinesin-II(consisting of two motor subunits and one nonmotor accessorysubunit) and retrograde cytoplasmic dynein motors that moveIFT particles and cargo to and from the distal tip of cilia.The IFT particle is composed of two complexes (A or B) thatcontain 16 to 18 polypeptides. Kinesin-II and complex B polypeptidesseem to regulate anterograde transport; dynein and complex Apolypeptides may regulate retrograde transport.
Scholey and colleagues (24–29) have performed exquisiteexperiments to examine the IFT machinery in C. elegans usingtime-lapse microscopy of GFP-tagged IFT motors and polypeptidesin conjunction with ciliary mutants. C. elegans chemosensorycilia contain two anterograde IFT motors: The canonical heterotrimerickinesin-II and homodimeric OSM-3 kinesin-II. Surprising, theseanterograde motors act cooperatively and redundantly, with kinesin-IIand OSM-3 building the cilium from the transition zone/basalbody to the middle region of the cilium (25). At the mid-zone,kinesin-II turns back and OSM-3 continues, acting alone to buildthe distal end of the cilium. Several interesting questionsare raised by this study. What regulates the transition fromcooperation to autonomy? Is this mechanism specific for wormcilia, or is this an evolutionarily conserved phenomenon?
In C. elegans, IFT builds and maintains cilia on dendritic endingsof sensory neurons. Ciliated sensory neurons located in thehead and tail (Figure 1) sense an extensive variety of environmentalsignals and mediate a wide spectrum of behaviors. For example,animals must locate food and males must find hermaphrodite mates.Of the 302 neurons in the hermaphrodite, 60 have dendritic endingsthat terminate in cilia (30). The male possesses an additional52 ciliated neurons (Figure 1) (31). In C. elegans, cilia aresensory and nonmotile, possessing a 9 + 0 doublet microtubulearray. Twenty-six of 60 ciliated neurons shared between thesexes have endings that are exposed to the environment and locatedin the head amphid, inner labial sensilla, and tail phasmidsensilla. It is interesting that many of the genes requiredfor the formation, maintenance, and function of C. elegans ciliahave human counterparts, which, when mutated, cause diseaseswith renal pathologies, including ADPKD, ARPKD, BBS, and NPHP(Table 1).
Figure 1. The ciliated nervous system of Caenorhabditis elegans. (A) Positions of nuclei of all ciliated neurons in the C. elegans hermaphrodite (30), reprinted with permission from reference 53. All but two of the 60 neurons are members of bilateral pairs and are represented by a single cell with L (for left side of animal) and R (for right side of animal). The asymmetric ciliated neurons are AQR and PQR. In the head, the four male-specific ciliated CEM neurons are indicated in red. In the hermaphrodite, the CEM undergo programmed cell death (64). The inset shows PKD-2::green fluorescence protein (GFP) localization in the CEM cilia (arrowheads) and cell bodies (arrow) in an adult C. elegans male. Scale bar = 10 µm. (B) Positions of nuclei of all ciliated neurons in the C. elegans adult male tail, adapted from reference 31. The male possesses an additional 52 ciliated neurons for a total of 112. All but two of the 52 male-specific ciliated neurons are arranged as left-right bilateral pairs. The asymmetric ciliated neurons are HOA and HOB, which mediate Lov behavior (51). The male tail has nine bilaterally arranged rays (numbered 1 to 9, anterior to posterior) required for response and turning behaviors (51). The inset shows PKD-2::GFP localization in the C. elegans adult male tail; indicated are the cell body of HOB (arrow) and cilia of HOB and ray 3 (arrowheads). Scale bar = 10 µm.
For identifying genes that are required for cilia developmentin C. elegans, classical genetic screens were performed on thebasis of the ability of chemosensory amphid and phasmid neuronsto fill with fluorescence dyes in living animals. Mutationsin 27 genes prevent dye uptake (the "Dyf," or dye filling defectivephenotype) (32,33). Mutations in 10 of these genes affect thestructure of all neuronal cilia (32). These cilium structuregenes encode IFT homologs. For example, osm-5 (for osmotic avoidancedefective) is homologous to the Chlamydomonas Complex B IFT88polypeptide and mouse ARPKD Tg737 gene (Polaris protein product)(34–36). Mutations in ift88, Tg737, and osm-5 result indefective ciliogenesis in Chlamydomonas, mouse, and worm, respectively(40,41). The osm-3 homomeric kinesin-II is required only foramphid and phasmid cilia development (32) and is expressed inonly chemosensory neurons (27,37), indicating that ciliogenesismay require at least two levels of regulation: General and specific.First, IFT builds and is common to all cilia. Once the ciliaryfoundation is laid, cell type–specific machineries perhapsrefine the cilium for certain functions (in the case of osm-3,chemosensation). In mammals, the KIF3A subunit of heterotrimerickinesin-II is essential for viability, with conventional knockoutmice dying as early embryos and failing to synthesize ciliain the embryonic node (38,39). Kidney-specific inactivationof the KIF3A subunit of heterotrimeric kinesin-II results inPKD in mice (42). In contrast, the human homologue of OSM-3is KIF17, a neuron-specific molecular motor that acts in neuronaldendrites (43). KIF17 involvement in ciliogenesis or kidneydevelopment has not been examined. The cloning and characterizationof the remaining C. elegans dyf genes will be informative aswill genetic screens designed to identify specialization genes.
The RFX transcription factor DAF-19 is required for the formationof all C. elegans cilia and regulates the activity of targetgenes by binding to an X-box promoter motif (15,36,45). TheC. elegans genome has >200 candidate X-box genes. The fruitfly Drosophila melanogaster uses a DAF-19 transcription factorto regulate sensory cilia formation via the X-box motif (46,47).Moreover, the mammalian transcription factor RFX3 is requiredfor the development of nodal cilia and L-R asymmetry (but isnot expressed in the kidney) (48). Combined, these data indicatethat both IFT machinery and the ciliary transcriptional apparatusmay be conserved from worm to human.
Comparative genomics was recently used by two groups to predictthe ciliary proteome (15,47). In brief, the genomes of nonciliatedorganisms were subtracted from ciliates to identify between200 and 700 cilia-specific genes in the "Flagellar and BasalBody" genome (reviewed in 49 and 50). This approach identifiedthe known players, including IFT components, polyductin/fibrocystin,BBS proteins, nephrocystins, ion channels, and intracellulartransport proteins. Model organisms will be essential in determiningthe function of the ciliary proteome.
Male mating behavior of C. elegans offers an intriguing modelto study the genetics of sensory behavior, cilia function, andADPKD. The C. elegans polycystins LOV-1 and PKD-2 are requiredfor male sensory behaviors. The C. elegans male executes a complexseries of stereotyped sub-behaviors to mate with the hermaphrodite.Mating behavior is shown in Supplemental Movie 1. The male nervoussystem possesses 381 neurons to the hermaphrodite’s 302.Sexual dimorphism is reflected in behavior: Many of the 87 male-specificneurons mediate male sensory behaviors (51). Males with severedefects in all sensory neuron cilia, such as the mutant osm-5,exhibit pleiotropic male mating defects in response, vulva location,and ejaculation (35,52). The only ciliated cells in C. elegansare chemosensory and mechanosensory neurons (30). The male has48 predicted ciliated sensory neurons in his tail and four inhis head (31). osm-5::gfp is expressed exclusively in ciliatedneurons, including male-specific expression in four CEM headneurons and neurons of the hook and rays (Figure 1) (35).
lov-1 and pkd-2 mutants are specifically response- and Lov-defective (Table 1, Supplemental Movie 2). lov-1 encodes theC. elegans homolog of the human polycystic kidney disease genePKD1 (52). Mutations in PKD1 or PKD2 account for 95% of ADPKD,a human genetic disorder that affects 1 in 1000 individuals.PKD-2 is the C. elegans homologue of the human PC-2 channel(encoded by the PKD2 gene) (54). PC-1 (encoded by PKD1) andPC-2 are proposed to form a receptor/channel complex (55). PC-2is a member of the transient receptor potential (TRP) ion channelfamily that has been implicated in a variety of sensory modalities.lov-1 and pkd-2 act in the same genetic pathway (54).
Consistent with a role in male sensation, lov-1 and pkd-2 areexpressed in the 21 male-specific exposed ciliated sensory neuronsthat mediate response (rays), vulva location (hook), and possiblychemotaxis to hermaphrodites (the head CEM; Figure 1). Usinga combination of translational GFP fusions and antibodies, weshowed that LOV-1 and PKD-2 proteins are enriched in sensorycilia (Figure 1) and that ciliary localization is a requisitefor polycystin function (52,54). Stunningly, sensory functionand ciliary localization of the C. elegans polycystins seemto be evolutionarily conserved. PC-2 localizes to renal cilia(5,6) and forms a mechanosensitive channel with PC-1 in primarycilium of cultured kidney cells (7). The powerful moleculargenetic tools of C. elegans will enable simultaneous dissectionof the molecular basis of male sensory behaviors, ciliary proteinlocalization, and PKD.
LOV-1 and all PC-1 family members share a similar architecture:A large extracellular domain (although there is no primary sequencehomology between the extracellular regions of LOV-1 and PC-1),a G protein–coupled receptor proteolysis site (GPS), 11transmembrane (TM) domains, and an intracellular polycystin-lipoxygenasealpha toxin (PLAT) domain located between TM1 and TM2 (55).The function of the evolutionarily conserved PLAT domain foundin all PC-1 family members remains an enigma. On the basis ofPLAT sequence homology, a nonredundant genetic PKD pathway,and PC ciliary subcellular localization in both C. elegans andmammals, we hypothesize that the PLAT domain may perform anevolutionarily conserved role in mediating PC-1 intracellularsignaling pathways. Overexpression of the LOV-1 PLAT domainin transgenic C. elegans dominantly interferes with responseand vulva location, suggesting that the PLAT domain dominantlyinterferes with the function of LOV-1 effectors (56).
For identifying targets of the PLAT domain, 1 x 106 cDNA werescreened for yeast two-hybrid interaction with the LOV-1 PLATdomain. ATP-2, the subunit of the ATP synthase, physicallyassociates with the LOV-1 PLAT domain (56). Moreover, C. elegansATP-2 and the human PC-1 PLAT domain physically interact, indicatingthat this interaction may be evolutionarily conserved. In additionto the expected mitochondria localization, ATP-2 and other ATPsynthase components co-localize with LOV-1 and PKD-2 in cilia.Whereas lov-1 and pkd-2 mutants are response- and Lov-defective,RNAi treatment of ATP synthase components or overexpressionof atp-2 causes only response but not Lov mating behavior defects.LOV-1 may have tissue-specific effectors. In other words, ATP-2may be required for polycystin-mediated signaling in ray neurons(with defects resulting in abnormal male response behaviors)but not the HOB hook neuron (as evidenced by wild-type vulvalocation behavior). Given the diverse clinical manifestationof ADPKD and broad distribution of the polycystins, it is likelythat the polycystins will have tissue-specific regulators andtargets. We propose that the ciliary localized ATP synthasemay play a previously unsuspected role in polycystin signaling.Whether the ATP synthase and PC-1 co-localize in the primarycilium of renal epithelial cells is unknown. Our studies usingC. elegans as a model for ADPKD promise new avenues to understandingpolycystin PLAT function and ciliary sensory signaling.
BBS is a multigenic, pleiotropic disorder characterized by kidneycysts/abnormalities, retinal degeneration, polydactyly, situsinversus, obesity, mental retardation, and hypogenitalism (OMIM#209900 at http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=209900).Several of these phenotypes bear resemblance to other humanciliary diseases. Six C. elegans homologs of the human BBS genes(bbs-1, bbs-2, bbs-3, bbs-5, bbs-7, and bbs-8) are expressedin ciliated sensory neurons and contain DAF-19–regulatedX-boxes in their promoter regions (Table 1) (6,13,15,57). bbs-7and bbs-8 mutants have abnormal cilia, compromised IFT rates,and defects in chemosensation (16). It is interesting that bbsand osm-3 mutants are similar in that only the distal end ofthe cilium is lacking (16,32), whereas complex B mutants lackboth proximal and distal ciliary regions. Combined, these datasuggest that the BBS proteins interact with the IFT machinery,but the physiologic relevance has yet to be determined.
NPHP is an autosomal recessive cystic kidney disease and mostfrequent genetic cause for end-stage renal failure in infants,children, and young adults (58). NPHP can also be associatedwith the extrarenal manifestations indicative of ciliary dysfunction,including retinitis pigmentosa and situs inversus. Mutationin one of four NPHP genes (NPHP1 through 4) results in NPHP.The NPHP1 protein product interacts with NPHP2, NPHP3, and NPHP4.NPHP1 and NPHP2 (also known as inversin) localize to cilia (12,59).The molecular functions underlying NPHP biochemical interactionsand ciliary localization are not well understood at this time.C. elegans has obvious NPHP1 and NPHP4 homologs (60,61), whereasNPHP2 and NPHP3 counterparts are less well conserved (Table 1;Jauregui AR, Barr M, unpublished observations). nphp-1 andnphp-4 are expressed in a subset of C. elegans sensory neurons,and their protein products localize to cilia (Jauregui AR, BarrM, unpublished observations). nphp-1 and nphp-4 single and doublehypomorphic mutants have wild-type cilia, as judged by dye filling.However, the nphp-1; nphp-4 double mutants have male matingdefects, suggesting genetic redundancy (Jauregui AR, Barr M,unpublished observations).
Worms Don’t Have It All: No Cystin (Cys), No Fibrocystin (PKHD1)
The C. elegans genome does not contain a cystin or fibrocystinhomolog. Cystin, a novel cilia-associated protein, is disruptedin the congenital polycystic kidney (cpk) mouse model of ARPKD(6,62). Human ARPKD is caused by mutation in the PKHD1 gene,which encodes fibrocystin, a novel receptor-like protein expressedon primary cilia (8,9,63). Originally thought to be chordate-specificgenes playing specialized roles in higher vertebrates, a fibrocystinhomolog is located in the unicellular Chlamydomonas genome (HongminQin and Joel Rosenbaum, personal communication). Unlike Chlamydomonas,C. elegans lacks motile cilia and has a more simple basal bodystructure. The Flagellar and Basal Body genome contains 326proteins that are found in humans and Chlamydomonas but notC. elegans, suggesting that this protein set (including fibrocystin)may be required for motile cilia and complex basal body formation(15).
The genomes of human, rat, and mouse all are known, which allowsthe cloning of human disease genes by means of comparative genomicanalysis (e.g., the identification of PKHD1 as the gene mutatedin ARPKD [8]). A great challenge is ascertaining gene function.C. elegans is clearly a powerful model system to study developmentand diseases of cilia. Systematic RNAi and classic genetic screenshave the potential to identify, in an unbiased manner, new genesthat are required for cilia development, maintenance, function,and signaling. The worm is your oyster.
C. elegans research in my laboratory is funded by grants fromthe National Institute of Diabetes and Digestive and KidneyDisorders and Polycystic Kidney Disease Foundation. The Barrlaboratory is a member of the Johns Hopkins PKD Center for Excellence.
Dr. Luis Rene Garcia (Texas A&M University) and Andrew Jauregui(University of Wisconsin) provided movies of wild-type and pkd-2male mating behavior. I am particularly grateful to Drs. JoelRosenbaum and Hongmin Qin (Yale) for ongoing discussions andthe two anonymous reviewers for constructive criticisms. I alsothank Doug, Peter, Luke, and Liam Tilton for constant support.
Footnotes
Published online ahead of print. Publication date availableat www.jasn.org.
The C. elegans Sequencing Consortium. Genome sequence of the nematode C. elegans: A platform for investigating biology.
Science 282
: 2012
–2018, 1998[Abstract/Free Full Text]
Watnick T, Germino G: From cilia to cyst.
Nat Genet 34
: 355
–356, 2003[CrossRef][Medline]
Pazour GJ: Intraflagellar transport and cilia-dependent renal disease: The ciliary hypothesis of polycystic kidney disease.
J Am Soc Nephrol 15
: 2528
–2536, 2004[Abstract/Free Full Text]
Pazour GJ, San Agustin JT, Follit JA, Rosenbaum JL, Witman GB: Polycystin-2 localizes to kidney cilia and the ciliary level is elevated in orpk mice with polycystic kidney disease.
Curr Biol 12
: R378
–R380, 2002[CrossRef][Medline]
Yoder BK, Hou X, Guay-Woodford LM: The polycystic kidney disease proteins, polycystin-1, polycystin-2, polaris, and cystin, are co-localized in renal cilia.
J Am Soc Nephrol 13
: 2508
–2516, 2002[Abstract/Free Full Text]
Nauli SM, Alenghat FJ, Luo Y, Williams E, Vassilev P, Li X, Elia AE, Lu W, Brown EM, Quinn SJ, Ingber DE, Zhou J: Polycystins 1 and 2 mediate mechanosensation in the primary cilium of kidney cells.
Nat Genet 33
: 129
–137, 2003[CrossRef][Medline]
Ward CJ, Hogan MC, Rossetti S, Walker D, Sneddon T, Wang X, Kubly V, Cunningham JM, Bacallao R, Ishibashi M, Milliner DS, Torres VE, Harris PC: The gene mutated in autosomal recessive polycystic kidney disease encodes a large, receptor-like protein.
Nat Genet 30
: 259
–269, 2002[CrossRef][Medline]
Wang S, Luo Y, Wilson PD, Witman GB, Zhou J: The autosomal recessive polycystic kidney disease protein is localized to primary cilia, with concentration in the basal body area.
J Am Soc Nephrol 15
: 592
–602, 2004[Abstract/Free Full Text]
Zhang MZ, Mai W, Li C, Cho SY, Hao C, Moeckel G, Zhao R, Kim I, Wang J, Xiong H, Wang H, Sato Y, Wu Y, Nakanuma Y, Lilova M, Pei Y, Harris RC, Li S, Coffey RJ, Sun L, Wu D, Chen XZ, Breyer MD, Zhao ZJ, McKanna JA, Wu G: PKHD1 protein encoded by the gene for autosomal recessive polycystic kidney disease associates with basal bodies and primary cilia in renal epithelial cells.
Proc Natl Acad Sci U S A 101
: 2311
–2316, 2004[Abstract/Free Full Text]
Ostrowski LE, Blackburn K, Radde KM, Moyer MB, Schlatzer DM, Moseley A, Boucher RC: A proteomic analysis of human cilia: Identification of novel components.
Mol Cell Proteomics 1
: 451
–465, 2002[Abstract/Free Full Text]
Otto EA, Schermer B, Obara T, O’Toole JF, Hiller KS, Mueller AM, Ruf RG, Hoefele J, Beekmann F, Landau D, Foreman JW, Goodship JA, Strachan T, Kispert A, Wolf MT, Gagnadoux MF, Nivet H, Antignac C, Walz G, Drummond IA, Benzing T, Hildebrandt F: Mutations in INVS encoding inversin cause nephronophthisis type 2, linking renal cystic disease to the function of primary cilia and left-right axis determination.
Nat Genet 34
: 413
–420, 2003[CrossRef][Medline]
Ansley SJ, Badano JL, Blacque OE, Hill J, Hoskins BE, Leitch CC, Kim JC, Ross AJ, Eichers ER, Teslovich TM, Mah AK, Johnsen RC, Cavender JC, Lewis RA, Leroux MR, Beales PL, Katsanis N: Basal body dysfunction is a likely cause of pleiotropic Bardet-Biedl syndrome.
Nature 425
: 628
–633, 2003[CrossRef][Medline]
Kim JC, Badano JL, Sibold S, Esmail MA, Hill J, Hoskins BE, Leitch CC, Venner K, Ansley SJ, Ross AJ, Leroux MR, Katsanis N, Beales PL: The Bardet-Biedl protein BBS4 targets cargo to the pericentriolar region and is required for microtubule anchoring and cell cycle progression.
Nat Genet 36
: 462
–470, 2004[CrossRef][Medline]
Li JB, Gerdes JM, Haycraft CJ, Fan Y, Teslovich TM, May-Simera H, Li H, Blacque OE, Li L, Leitch CC, Lewis RA, Green JS, Parfrey PS, Leroux MR, Davidson WS, Beales PL, Guay-Woodford LM, Yoder BK, Stormo GD, Katsanis N, Dutcher SK: Comparative genomics identifies a flagellar and basal body proteome that includes the BBS5 human disease gene.
Cell 117
: 541
–552, 2004[CrossRef][Medline]
Blacque OE, Reardon MJ, Li C, McCarthy J, Mahjoub MR, Ansley SJ, Badano JL, Mah AK, Beales PL, Davidson WS, Johnsen RC, Audeh M, Plasterk RH, Baillie DL, Katsanis N, Quarmby LM, Wicks SR, Leroux MR: Loss of C. elegans BBS-7 and BBS-8 protein function results in cilia defects and compromised intraflagellar transport.
Genes Dev 18
: 1630
–1642, 2004[Abstract/Free Full Text]
Pazour GJ, Rosenbaum JL: Intraflagellar transport and cilia-dependent diseases.
Trends Cell Biol 12
: 551
–555, 2002[CrossRef][Medline]
Praetorius HA, Spring KR: Bending the MDCK cell primary cilium increases intracellular calcium.
J Membr Biol 184
: 71
–79, 2001[CrossRef][Medline]
Praetorius HA, Spring KR: Removal of the MDCK cell primary cilium abolishes flow sensing.
J Membr Biol 191
: 69
–76, 2003[CrossRef][Medline]
Praetorius HA, Spring KR: The renal cell primary cilium functions as a flow sensor.
Curr Opin Nephrol Hypertens 12
: 517
–520, 2003[Medline]
McGrath J, Brueckner M: Cilia are at the heart of vertebrate left-right asymmetry.
Curr Opin Genet Dev 13
: 385
–392, 2003[CrossRef][Medline]
Kozminski KG, Forscher P, Rosenbaum JL: Three flagellar motilities in Chlamydomonas unrelated to flagellar beating. Video supplement.
Cell Motil Cytoskeleton 39
: 347
–348 1998[Medline]
Scholey JM, Ou G, Snow J, Gunnarson A: Intraflagellar transport motors in Caenorhabditis elegans neurons.
Biochem Soc Trans 32[Suppl]
: 682
–684, 2004[CrossRef]
Snow JJ, Ou G, Gunnarson AL, Walker MR, Zhou HM, Brust-Mascher I, Scholey JM: Two anterograde intraflagellar transport motors cooperate to build sensory cilia on C. elegans neurons.
Nat Cell Biol 6
: 1109
–1113, 2004[CrossRef][Medline]
Signor D, Rose LS, Scholey JM: Analysis of the roles of kinesin and dynein motors in microtubule-based transport in the Caenorhabditis elegans nervous system.
Methods 22
: 317
–325, 2000[CrossRef][Medline]
Signor D, Wedaman KP, Rose LS, Scholey JM: Two heteromeric kinesin complexes in chemosensory neurons and sensory cilia of Caenorhabditis elegans.Mol Biol Cell 10
: 345
–360, 1999[Abstract/Free Full Text]
Signor D, Wedaman KP, Orozco JT, Dwyer ND, Bargmann CI, Rose LS, Scholey JM: Role of a class DHC1b dynein in retrograde transport of IFT motors and IFT raft particles along cilia, but not dendrites, in chemosensory neurons of living Caenorhabditis elegans.J Cell Biol 14
7 519
–530, 1999
Orozco JT, Wedaman KP, Signor D, Brown H, Rose L, Scholey JM: Movement of motor and cargo along cilia.
Nature 398
: 674
, 1999[CrossRef][Medline]
White JG, Southgate E, Thomson JN, Brenner S: The structure of the nervous system of the nematode Caenorhabditis elegans: the mind of a worm.
Phil Trans R Soc Lond 314
: 1
–340, 1986[CrossRef]
Sulston JE, Albertson DG, Thomson JN: The Caenorhabditis elegans male: Postembryonic development of nongonadal structures.
Dev Biol 78
: 542
–576, 1980[CrossRef][Medline]
Starich TA, Herman RK, Kari CK, Yeh WH, Schackwitz WS, Schuyler MW, Collet J, Thomas JH, Riddle DL: Mutations affecting the chemosensory neurons of Caenorhabditis elegans.Genetics 139
: 171
–188, 1995[Abstract]
Pazour GJ, Dickert BL, Vucica Y, Seeley ES, Rosenbaum JL, Witman GB, Cole DG: Chlamydomonas IFT88 and its mouse homologue, polycystic kidney disease gene tg737, are required for assembly of cilia and flagella.
J Cell Biol 151
: 709
–718, 2000[Abstract/Free Full Text]
Qin H, Rosenbaum JL, Barr MM: An autosomal recessive polycystic kidney disease gene homolog is involved in intraflagellar transport in C. elegans ciliated sensory neurons.
Curr Biol 11
: 457
–461, 2001[CrossRef][Medline]
Haycraft CJ, Swoboda P, Taulman PD, Thomas JH, Yoder BK: The C. elegans homolog of the murine cystic kidney disease gene Tg737 functions in a ciliogenic pathway and is disrupted in osm-5 mutant worms.
Development 128
: 1493
–1505, 2001[Abstract]
Tabish M, Siddiqui ZK, Nishikawa K, Siddiqui SS: Exclusive expression of C. elegans osm-3 kinesin gene in chemosensory neurons open to the external environment.
J Mol Biol 247
: 377
–389, 1995[CrossRef][Medline]
Marszalek JR, Ruiz-Lozano P, Roberts E, Chien KR, Goldstein LS: Situs inversus and embryonic ciliary morphogenesis defects in mouse mutants lacking the KIF3A subunit of kinesin-II.
Proc Natl Acad Sci U S A 96
: 5043
–5048, 1999[Abstract/Free Full Text]
Takeda S, Yonekawa Y, Tanaka Y, Okada Y, Nonaka S, Hirokawa N: Left-right asymmetry and kinesin superfamily protein KIF3A: New insights in determination of laterality and mesoderm induction by kif3A–/– mice analysis.
J Cell Biol 145
: 825
–836, 1999[Abstract/Free Full Text]
Murcia NS, Richards WG, Yoder BK, Mucenski ML, Dunlap JR, Woychik RP: The Oak Ridge Polycystic Kidney (orpk) disease gene is required for left-right axis determination.
Development 127
: 2347
–2355, 2000[Abstract]
Taulman PD, Haycraft CJ, Balkovetz DF, Yoder BK: Polaris, a protein involved in left-right axis patterning, localizes to basal bodies and cilia.
Mol Biol Cell 12
: 589
–599, 2001[Abstract/Free Full Text]
Lin F, Hiesberger T, Cordes K, Sinclair AM, Goldstein LS, Somlo S, Igarashi P: Kidney-specific inactivation of the KIF3A subunit of kinesin-II inhibits renal ciliogenesis and produces polycystic kidney disease.
Proc Natl Acad Sci U S A 100
: 5286
–5291, 2003[Abstract/Free Full Text]
Setou M, Nakagawa T, Seog DH, Hirokawa N: Kinesin superfamily motor protein KIF17 and mLin-10 in NMDA receptor-containing vesicle transport.
Science 288
: 1796
–1802, 2000[Abstract/Free Full Text]
Haycraft CJ, Schafer JC, Zhang Q, Taulman PD, Yoder BK: Identification of CHE-13, a novel intraflagellar transport protein required for cilia formation.
Exp Cell Res 284
: 251
–263, 2003[CrossRef][Medline]
Swoboda P, Adler HT, Thomas JH: The RFX-type transcription factor DAF-19 regulates sensory neuron cilium formation in C. elegans.Mol Cell 5
: 411
–421, 2000[CrossRef][Medline]
Dubruille R, Laurencon A, Vandaele C, Shishido E, Coulon-Bublex M, Swoboda P, Couble P, Kernan M, Durand B: Drosophila regulatory factor X is necessary for ciliated sensory neuron differentiation.
Development 129
: 5487
–5498, 2002[Abstract/Free Full Text]
Bonnafe E, M. Touka M, AitLounis A, Baas D, Barras E, Ucla C, Moreau A, Flamant F, Dubruille R, Couble P, Collignon J, Durand B, Reith W: The transcription factor RFX3 directs nodal cilium development and left-right asymmetry specification.
Mol Cell Biol 24
: 4417
–4427, 2004[Abstract/Free Full Text]
Pazour GJ: Comparative genomics: Prediction of the ciliary and basal body proteome.
Curr Biol 14
: R575
–R577, 2004[CrossRef][Medline]
Snell WJ, Pan J, Wang Q: Cilia and flagella revealed: From flagellar assembly in Chlamydomonas to human obesity disorders.
Cell 117
: 693
–697, 2004[CrossRef][Medline]
Liu KS, Sternberg PW: Sensory regulation of male mating behavior in Caenorhabditis elegans.
Neuron 14
: 79
–89, 1995[CrossRef][Medline]
Barr MM, Sternberg PW: A polycystic kidney-disease gene homologue required for male mating behaviour in C. elegans.Nature 401
: 386
–389, 1999[CrossRef][Medline]
Collet J, Spike CA, Lundquist EA, Shaw JE, Herman RK: Analysis of osm-6, a gene that affects sensory cilium structure and sensory neuron function in Caenorhabditis elegans.Genetics 148
: 187
–200, 1998[Abstract/Free Full Text]
Barr MM, DeModena J, Braun D, Nguyen CQ, Hall DH, Sternberg PW: The Caenorhabditis elegans autosomal dominant polycystic kidney disease gene homologs lov-1 and pkd-2 act in the same pathway.
Curr Biol 11
: 1341
–1346, 2001[CrossRef][Medline]
Igarashi P, Somlo S: Genetics and pathogenesis of polycystic kidney disease.
J Am Soc Nephrol 13
: 2384
–2398, 2002[Free Full Text]
Hu J, Barr MM: ATP-2 interacts with the PLAT domain of LOV-1 and is involved in C. elegans polycystin signaling.
Mol Biol Cell Nov 24, 2004 [Epub ahead of print]
Fan Y, Esmail MA, Ansley SJ, Blacque OE, Boroevich K, Ross AJ, Moore SJ, Badano JL, May-Simera H, Compton DS, Green JS, Lewis RA, van Haelst MM, Parfrey PS, Baillie DL, Beales PL, Katsanis N, Davidson WS, Leroux MR: Mutations in a member of the Ras superfamily of small GTP-binding proteins causes Bardet-Biedl syndrome.
Nat Genet 36
: 989
–993, 2004[CrossRef][Medline]
Watanabe D, Saijoh Y, Nonaka S, Sasaki G, Ikawa Y, Yokoyama T, Hamada H: The left-right determinant Inversin is a component of node monocilia and other 9+0 cilia.
Development 130
: 1725
–1734, 2003[Abstract/Free Full Text]
Otto E, Hoefele J, Ruf R, Mueller AM, Hiller KS, Wolf MT, Schuermann MJ, Becker A, Birkenhager R, Sudbrak R, Hennies HC, Nurnberg P, Hildebrandt F: A gene mutated in nephronophthisis and retinitis pigmentosa encodes a novel protein, nephroretinin, conserved in evolution.
Am J Hum Genet 71
: 1161
–1167, 2002[CrossRef][Medline]
Hildebrandt F, Otto E: Molecular genetics of nephronophthisis and medullary cystic kidney disease.
J Am Soc Nephrol 11
: 1753
–1761, 2000[Abstract/Free Full Text]
Hou X, Mrug M, Yoder BK, Lefkowitz EJ, Kremmidiotis G, D’Eustachio P, Beier DR, Guay-Woodford LM: Cystin, a novel cilia-associated protein, is disrupted in the cpk mouse model of polycystic kidney disease.
J Clin Invest 109
: 533
–540, 2002[CrossRef][Medline]
Ward CJ, Yuan D, Masyuk TV, Wang X, Punyashthiti R, Whelan S, Bacallao R, Torra R, LaRusso NF, Torres VE, Harris PC: Cellular and subcellular localization of the ARPKD protein; fibrocystin is expressed on primary cilia.
Hum Mol Genet 12
: 2703
–2710, 2003[Abstract/Free Full Text]
Sulston JE, Horvitz HR: Post-embryonic cell lineages of the nematode, Caenorhabditis elegans.Dev Biol 56
: 110
–156, 1977[CrossRef][Medline]
Kamath RS, Fraser AG, Dong Y, Poulin G, Durbin R, Gotta M, Kanapin A, LeBot N, Moreno S, Sohrmann M, Welchman DP, Zipperlen P, Ahringer J: Systemic functional analysis of the Caenorhabditis elegans genome using RNAi.
Nature 421
: 231
–237, 2003[CrossRef][Medline]
Gonczy P, Echeverri C, Oegema K, Coulson A, Jones SJ, Copley RR, Duperon J, Oegema J, Brehm M, Cassin E, Hannak E, Kirkham M, Pichler S, Flohrs K, Goessen A, Leidel S, Alleaume AM, Martin C, Ozlu N, Bork P, Hyman AA: Functional genomic analysis of cell division in C. elegans using RNAi of genes on chromosome III.
Nature 408
: 331
–336, 2000[CrossRef][Medline]
Pothof J, Van Haaften G, Thijssen K, Kamath RS, Fraser AG, Ahringer J, Plasterk RH, Tijsterman M: Identification of genes that protect the C. elegans genome against mutations by genome-wide RNAi.
Genes Dev 17
: 443
–448, 2003[Abstract/Free Full Text]
Piano F, Schetter AJ, Morton DG, Gunsalus KC, Reinke V, Kim SK, Kemphues KJ: Gene clustering based on RNAi phenotypes of ovary-enriched genes in C. elegans.Curr Biol 12
: 1959
–1964, 2002[CrossRef][Medline]
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Top
Abstract
Introduction
subunit of the ATP synthase, physically associates with the LOV-1 PLAT domain (56). Moreover, C. elegans ATP-2 and the human PC-1 PLAT domain physically interact, indicating that this interaction may be evolutionarily conserved. In addition to the expected mitochondria localization, ATP-2 and other ATP synthase components co-localize with LOV-1 and PKD-2 in cilia. Whereas lov-1 and pkd-2 mutants are response- and Lov-defective, RNAi treatment of ATP synthase components or overexpression of atp-2 causes only response but not Lov mating behavior defects. LOV-1 may have tissue-specific effectors. In other words, ATP-2 may be required for polycystin-mediated signaling in ray neurons (with defects resulting in abnormal male response behaviors) but not the HOB hook neuron (as evidenced by wild-type vulva location behavior). Given the diverse clinical manifestation of ADPKD and broad distribution of the polycystins, it is likely that the polycystins will have tissue-specific regulators and targets. We propose that the ciliary localized ATP synthase may play a previously unsuspected role in polycystin signaling. Whether the ATP synthase and PC-1 co-localize in the primary cilium of renal epithelial cells is unknown. Our studies using C. elegans as a model for ADPKD promise new avenues to understanding polycystin PLAT function and ciliary sensory signaling. 
