The primary cilium, a microtubule-based organelle found in most cells, is a centre for mechano-sensing fluid movement and cellular signalling, notably through the Hedgehog pathway. We recently found that each lens fibre cell has an apically situated primary cilium that is polarised to the side of the cell facing the anterior pole of the lens. The direction of polarity is similar in neighbouring cells so that in the global view, lens fibres exhibit planar cell polarity (PCP) along the equatorial-anterior polar axis. Ciliogenesis has been associated with the establishment of PCP, although the exact relationship between PCP and the role of cilia is still controversial. To test the hypothesis that the primary cilia have a role in coordinating the precise alignment/orientation of the fibre cells, IFT88, a key component of the intraflagellar transport (IFT) complex, was removed specifically from the lens at different developmental stages using several lens-specific Cre-expressing mouse lines (MLR10- and LR-Cre). Irrespective of which Cre-line was adopted, both demonstrated that in IFT88-depleted cells, the ciliary axoneme was absent or substantially shortened, confirming the disruption of primary cilia formation. However no obvious histological defects were detected even when IFT88 was removed from the lens placode as early as E9.5. Specifically, the lens fibres aligned/oriented towards the poles to form the characteristic Y-shaped sutures as normal. Consistent with this, in primary lens epithelial explants prepared from these conditional knockout mouse lenses, the basal bodies still showed polarised localisation at the apical surface of elongating cells upon FGF-induced fibre differentiation. We further investigated the lens phenotype in knockouts of Bardet-Biedl Syndrome (BBS) proteins 4 and 8, the components of the BBSome complex which modulate ciliary function. In these BBS4 and 8 knockout lenses, again we found the pattern of the anterior sutures formed by the apical tips of elongating/migrating fibres were comparable to the control lenses. Taken together, these results indicate that primary cilia do not play an essential role in the precise cellular alignment/orientation of fibre cells. Thus, it appears that in the lens cilia are not required to establish PCP.

Anatomy and Histology School of Medical Sciences and Bosch Institute University of Sydney Sydney NSW 2006 Australia

Department of Cell Developmental and Integrative Biology University of Alabama at Birmingham Birmingham AL 35294 USA

Department of Transcriptional Regulation Institute of Molecular Genetics Prague CZ 14220 Czech Republic

Genetics and Genomic Medicine University College London Institute of Child Health London WC1N 1EH UK

Institute of Zoology Johannes Gutenberg University Mainz 55128 Germany

Save Sight Institute The University of Sydney Sydney NSW 2000 Australia

Zobrazit více v PubMed

Berbari NF, O’Connor AK, Haycraft CJ, Yoder BK. The primary cilium as a complex signaling center. Curr Biol. 2009;19:R526–35. PubMed PMC

Briscoe J, Therond PP. The mechanisms of Hedgehog signalling and its roles in development and disease. Nat Rev Mol Cell Biol. 2013;14:416–29. PubMed

Choi JJ, Ting CT, Trogrlic L, Milevski SV, Familari M, Martinez G, de Iongh RU. A role for smoothened during murine lens and cornea development. PLoS One. 2014;9:e108037. PubMed PMC

Dawes LJ, Sugiyama Y, Lovicu FJ, Harris CG, Shelley EJ, McAvoy JW. Interactions between lens epithelial and fiber cells reveal an intrinsic self-assembly mechanism. Dev Biol. 2014;385:291–303. PubMed PMC

Dora NJ, Collinson JM, Hill RE, West JD. Hemizygous Le-Cre transgenic mice have severe eye abnormalities on some genetic backgrounds in the absence of LoxP sites. PLoS One. 2014;9:e109193. PubMed PMC

Forsythe E, Beales PL. Bardet-Biedl syndrome. Eur J Hum Genet. 2013;21:8–13. PubMed PMC

Gongal PA, French CR, Waskiewicz AJ. Aberrant forebrain signaling during early development underlies the generation of holoprosencephaly and coloboma. Biochim Biophys Acta. 2011;1812:390–401. PubMed

Guirao B, Meunier A, Mortaud S, Aguilar A, Corsi JM, Strehl L, Hirota Y, Desoeuvre A, Boutin C, Han YG, Mirzadeh Z, Cremer H, Montcouquiol M, Sawamoto K, Spassky N. Coupling between hydrodynamic forces and planar cell polarity orients mammalian motile cilia. Nat Cell Biol. 2010;12:341–50. PubMed

Gunhaga L. The lens: a classical model of embryonic induction providing new insights into cell determination in early development. Philos Trans R Soc Lond B Biol Sci. 2011;366:1193–203. PubMed PMC

Haycraft CJ, Banizs B, Aydin-Son Y, Zhang Q, Michaud EJ, Yoder BK. Gli2 and Gli3 localize to cilia and require the intraflagellar transport protein polaris for processing and function. PLoS Genet. 2005;1:e53. PubMed PMC

Haycraft CJ, Zhang Q, Song B, Jackson WS, Detloff PJ, Serra R, Yoder BK. Intraflagellar transport is essential for endochondral bone formation. Development. 2007;134:307–16. PubMed

Jones C, Roper VC, Foucher I, Qian D, Banizs B, Petit C, Yoder BK, Chen P. Ciliary proteins link basal body polarization to planar cell polarity regulation. Nat Genet. 2008;40:69–77. PubMed

Kreslova J, Machon O, Ruzickova J, Lachova J, Wawrousek EF, Kemler R, Krauss S, Piatigorsky J, Kozmik Z. Abnormal lens morphogenesis and ectopic lens formation in the absence of beta-catenin function. Genesis. 2007;45:157–68. PubMed

Kulaga HM, Leitch CC, Eichers ER, Badano JL, Lesemann A, Hoskins BE, Lupski JR, Beales PL, Reed RR, Katsanis N. Loss of BBS proteins causes anosmia in humans and defects in olfactory cilia structure and function in the mouse. Nat Genet. 2004;36:994–8. PubMed

Kuszak JR, Mazurkiewicz M, Zoltoski R. Computer modeling of secondary fiber development and growth: I. Nonprimate lenses. Mol Vis. 2006;12:251–70. PubMed

Lehman JM, Michaud EJ, Schoeb TR, Aydin-Son Y, Miller M, Yoder BK. The Oak Ridge Polycystic Kidney mouse: modeling ciliopathies of mice and men. Dev Dyn. 2008;237:1960–71. PubMed PMC

May-Simera HL, Petralia RS, Montcouquiol M, Wang YX, Szarama KB, Liu Y, Lin W, Deans MR, Pazour GJ, Kelley MW. Ciliary proteins Bbs8 and Ift20 promote planar cell polarity in the cochlea. Development. 2015;142:555–66. PubMed PMC

Mirzadeh Z, Han YG, Soriano-Navarro M, Garcia-Verdugo JM, Alvarez-Buylla A. Cilia organize ependymal planar polarity. J Neurosci. 2010;30:2600–10. PubMed PMC

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. 2000;127:2347–55. PubMed

Mykytyn K, Mullins RF, Andrews M, Chiang AP, Swiderski RE, Yang B, Braun T, Casavant T, Stone EM, Sheffield VC. Bardet-Biedl syndrome type 4 (BBS4)-null mice implicate Bbs4 in flagella formation but not global cilia assembly. Proc Natl Acad Sci U S A. 2004;101:8664–9. PubMed PMC

Ross AJ, May-Simera H, Eichers ER, Kai M, Hill J, Jagger DJ, Leitch CC, Chapple JP, Munro PM, Fisher S, Tan PL, Phillips HM, Leroux MR, Henderson DJ, Murdoch JN, Copp AJ, Eliot MM, Lupski JR, Kemp DT, Dollfus H, Tada M, Katsanis N, Forge A, Beales PL. Disruption of Bardet-Biedl syndrome ciliary proteins perturbs planar cell polarity in vertebrates. Nat Genet. 2005;37:1135–40. PubMed

Satir P, Pedersen LB, Christensen ST. The primary cilium at a glance. J Cell Sci. 2010;123:499–503. PubMed PMC

Sugiyama Y, Lovicu FJ, McAvoy JW. Planar cell polarity in the mammalian eye lens. Organogenesis. 2011;7:191–201. PubMed PMC

Sugiyama Y, McAvoy JW. Analysis of PCP defects in mammalian eye lens. Methods Mol Biol. 2012;839:147–56. PubMed PMC

Sugiyama Y, Stump RJ, Nguyen A, Wen L, Chen Y, Wang Y, Murdoch JN, Lovicu FJ, McAvoy JW. Secreted frizzled-related protein disrupts PCP in eye lens fiber cells that have polarised primary cilia. Dev Biol. 2010;338:193–201. PubMed PMC

Sung CH, Leroux MR. The roles of evolutionarily conserved functional modules in cilia-related trafficking. Nat Cell Biol. 2013;15:1387–97. PubMed PMC

Tadenev AL, Kulaga HM, May-Simera HL, Kelley MW, Katsanis N, Reed RR. Loss of Bardet-Biedl syndrome protein-8 (BBS8) perturbs olfactory function, protein localization, and axon targeting. Proc Natl Acad Sci U S A. 2011;108:10320–5. PubMed PMC

Wallingford JB, Mitchell B. Strange as it may seem: the many links between Wnt signaling, planar cell polarity, and cilia. Genes Dev. 2011;25:201–13. PubMed PMC

Waters AM, Beales PL. Ciliopathies: an expanding disease spectrum. Pediatr Nephrol. 2011;26:1039–56. PubMed PMC

Yang J, Liu X, Yue G, Adamian M, Bulgakov O, Li T. Rootletin, a novel coiled-coil protein, is a structural component of the ciliary rootlet. J Cell Biol. 2002;159:431–40. PubMed PMC

Zhao H, Yang Y, Rizo CM, Overbeek PA, Robinson ML. Insertion of a Pax6 consensus binding site into the alphaA-crystallin promoter acts as a lens epithelial cell enhancer in transgenic mice. Invest Ophthalmol Vis Sci. 2004;45:1930–9. PubMed

Analysis of genome-wide knockout mouse database identifies candidate ciliopathy genes