Cilia:&Movers,&Shakers,&and&Receivers&

James&Hejna&Osamu&Chisaka&Graduate&School&of&Biostudies&

Kyoto&University&

15Jan2016&

1.&&What&are&cilia?&

2.&&Ciliogenesis&

3.&&Ciliopathies&

5.&Primary&cilia&as&antennas&

Outline&

4.&&Trafficking&in&and&out&of&cilia&

Anton&van&Leeuwenhoek’&drawings&of&sperm,&ca.&1679&&

Portrait&of&Leeuwenhoek&by&Jan&Verkolje.&&Rijksmuseum.nl&

Leeuwenoek.&Rabbit&and&dog&sperm.&&Commons.wikimedia.org&

Commons.wikimedia.org&

We&have&known&about&flagella&for&hundreds&of&years…&

Afzelius&BA&(1976)&A&human&syndrome&caused&by&immo^le&cilia,&Science&193:317_9&

Kartagener’s&Syndrome:&&defec^ve&dynein&arms=&bronchial&infec^ons,&immobile&sperm,&situs&inversus&

Normal&Sperm& Pa^ent&(L.P.)&Sperm& Diagram&of&Normal&Sperm&

But&it&wasn’t&un^l&1976&that&a&physical&defect&was&acributed&to&immobile&sperm&&

Fundamentals:&&What&are&cilia?&&What&are&flagella?&&Are&they&precy&much&the&same&thing?&

Yes.&&Eukaryo^c&&mo^le&cilia&are&precy&similar&to&eukaryo^c&flagella.&

The&term&“Intraflagellar&transport”&(IFT)&applies&to&both&flagella&and&cilia.&

Cilia&are&generally&shorter&(~6_10&μm)&than&flagella&(~150&μm)&&

The&mo.ons&of&cilia&and&flagella&are&different,&although&the&gross&features&are&similar&

Cells&that&are&mul^_ciliated&tend&to&have&their&cilia&beat&in&a&coordinated&fashion&

A&brief&digression&on&prokaryo.c&flagella&

The&filament&component&of&bacterial&flagella&is&a&protein&called&flagellin&

Prokaryo.c&flagella&are&structurally&different&from&eukaryo^c&flagella/cilia&

Mo^on&is&driven&by&a&rotary&motor&mechanism,&like&a&crank.&

Recall&that&flagellin&is&recognized&by&the&innate&immune&system&in&both&plants&and&animals&

Pallen&and&Matzke&(2006)Nat&Rev&Microbiol&4,&784_790&

Prokaryo.c&Flagellum&

Rotary&Engine&

No&membrane&

Assembly&by&a&secre^on&type&system&

The&rotor&is&driven&by&a&proton&pump&

Pallen&and&Matzke&(2006)Nat&Rev&Microbiol&4,&784_790&

Archaeal&Flagella&resemble&bacterial&flagella,&but&the&composi.on&and&assembly&are&different&

The&surprisingly&diverse&ways&that&prokaryotes&move&Ken&F.&Jarrell&&&Mark&J.&McBride&Nature'Reviews'Microbiology'6,&466_476&(June&2008)&

What&types&of&organisms&have&cilia/flagella?&

Plants?&

Animals?&

Fungi?&

Bacteria?&

Unicellular&Algae&(Chlamydomonas)?&

Archaebacteria?&

!&

!&

!&

!&

!& (some&species,&e.g.,&chytrids,&have&mo^le&gametes)&

!& (Some&species,&like&Ginko&and&moss,&have&mo^le&sperm)&

(these&are&en^rely&different&from&eukaryo^c&flagella)&

(these&are&en^rely&different&from&eukaryo^c&flagella)&

Protozoans&(Tetrahymena)?& !&

hcps://s10.lite.msu.edu/res/msu/botonl/b_online/fo47/ginkgo/ogura.htm&

1896,&Sakugoru&Hirase&described&"Spermatozoid&of&Ginkgo'biloba”:''mo:le'sperm&&

&

~100&μm&&

hcp://kwanten.home.xs4all.nl/ovule.htm&

Prof.&Jin&Murata&

“The&symbolic&Ginkgo&tree&from&which&zoospore&was&discovered”&

Model&Organisms&for&structural&studies&of&cilia&and&flagella&

Tetrahymena&

©&Dennis&Kunkel&Microscopy,&Inc/Visuals&Unlimited/Corbis&

©&Carolina&Biological/Visuals&Unlimited/Corbis&

Chlamydomonas&

George&Watchmaker&Lawrence&Livermore&Na^onal&Laboratory&

Sea&Urchin&sperm&

Other&model&organisms&include:&Trypanosomes,&Drosophila,&C.&elegans,&zebrafish,&mice,&dog&(MDCK&cells),&and&cultured&human&cells&(e.g.,&re^nal&pigmented&epithethelial&cells).&Even&HEK293&cells&have&primary&cilia,&but&they&are&a&bit&small&and&hard&to&visualize.&&

(a&Ciliate)&

Diversity of cilia types in vertebrates (e.g., mammals).

Choksi S P et al. Development 2014;141:1427-1441

Luse,&S.&(1956)&J&Biophys&Biochem&Cytol.&2:531_42.&

(Associa^on&with&clearance&of&the&airway:1930s)&

1679&

mid_1950s&

Ca.&1961&

Ca.&1956&

Why&was&there&an&explosion&of&ar^cles&on&cilia&in&the&1950s&and&1960s?&&

Fliegauf&M&et&al.&(2007) Nat&Rev&Mol&Cell&Biol.&8:880_93.&

Not&all&9+2&cilia&are&mo.le,&and&not&all&9+0&cilia&are&nonLmo.le&

Animals:&&where&can&we&find&cilia?&

Human&ES&cells&

He&et&al.&(2014)&Mol&Biol&Cell.&25:1715_29&

Almost&all&mammalian&cells&are&ciliated—with&either&specialized&cilia&or&primary&cilia.&

Mo.le&&cilia&&are&generally&“9+2”&and&primary&cilia&are&generally&“9+0”&

Cardenas_Rodriguez&M,&Badano&JL.&2009.&Ciliary&biology:&Understanding&the&cellular&and&gene^c&basis&of&human&ciliopathies.&Am&J&Med&Genet&Part&C&Semin&Med&Genet&151C:263&–&280&

Plasma&membrane&

Transi^on&Zone&Basal&body&is&derived&from&the&mother&centriole&

microtubules&

There&may&be&up&to&300&proteins&either&in&cilia&or&related&to&ciliogenesis&&

No&central&pair&

Review&of&Microtubules,&Dynein,&and&Kinesin&

1.&&Microtubules:&&heterodimers&of&α_tubulin&and&β_tubulin,&both&of&which&bind&GTP.&&&&&&&Microtubules&are&a&major&part&of&the&intracellular&cytoskeleton,&and&are&&&&&&&&&&&&&&&&&&&&&&

&involved&in&localiza^on&of&organelles,&intracellular&transport,&as&well&as&the&&&&&&&mito^c&spindle.&

•  &Polarity:&&there&is&a&–&end&and&a&+&end.&Hydrolysis&of&GTP&to&GDP&destabilizes&microtubules.&

•  &The&minus&end&(α)&is&(o{en)&anchored&in&the&basal&body,&and&the&plus&end&(β)&is&the&growing&end.&&&

•  &In&axonemes,&the&peripheral&microtubules&have&a&&doublet&structure,&&13&in&ring&A&plus&10&in&ring&B&&

•  &In&the&cytoskeleton,&microtubules&are&built&from&α_β&heterodimers&that&form&a&hollow&tube&with&13&units&per&helical&repeat.&&&

(top&view)&

A&B&

α& β&β&β& α&α&GTP&GDP&GDP& GTP&GTP&GTP&

www.mechanobio.info&

_& +&

Figure 16-11 Molecular Biology of the Cell (© Garland Science 2008)

The&microtubules&in&axonemes&grow&at&the&“+”&.p&

GTP&

α_Tubulin&TUBA1A*&TUBA1B&TUBA1C&TUBA3C/D&TUBA3E&TUBA4A*&TUBA8*&

β_Tubulin&TUBB*&TUBB1(*)&TUBB2A*&TUBB2B*&TUBB2C&TUBB3*&TUBB4Q&TUBB6&

γ_tubulin&&TUBG1*&TUBG2&TUBGCP2&TUBGCP3&TUBGCP4*&TUBGCP5&TUBGCP6*&

δ_tubulin&TUBD1&ε_tubulin&TUBE1&

As&early&as&the&1980s,&people&speculated&that&different&isoforms&would&confer&different&proper.es&to&microtubules&

•  With&post_transla^onal&modifica^ons&and&differen^ally&expressed&isoforms,&we&have&a&large&amount&of&combinatorial&diversity&

Keep&in&mind&that&much&of&what&we&know&is&based&on&model&organisms&

In&Flies,&all&9+2&mo^le&axonemes&u^lize&α84B&α_tubulin&plus&β2&β_tubulin&&

In&worms,&sensory&cilia&work&op^mally&with&TBA_6&and&TBA_9&α_tubulins,&and&TBB_4&β_tubulin&

*&Muta^ons&associated&with&human&gene^c&diseases&

Janke&and&Bulinski&(2011)&Nat&Rev&Mol&Cell&Biol.&:773_86&

HDAC6&deacetylates&α_tubulin&during&cilia&disassembly&&

The&CLtermini&of&αLtubulin&and&βLtubulin&are&postLtransla.onally&modified&&

A&tubulin_specific&lysine&acetyltransferase&modifies&the&α&subunit&

In&cycling&cells,&cilia&are&disassembled,&and&the&centrioles&organize&the&mito^c&spindle&during&M&phase&&

Wloga&D&et&al.&(2009)&Dev&Cell&16:867_76&

Overexpression&of&a&DominantLnega.ve&GlycylLligase,&TTLL3&causes&defec.ve&axoneme&assembly&in&Tetrahymena&

WT&

B_G&=&Dominant&Nega^ve&overexpressing&axonemes&

Deple.on&of&TTLL3&Produces&Defects&in&the&LR&Asymmetry&in&Zebrafish&

Le{y&is&a&TGFβ&family&member&that&determines&LR&Asymmetry&

cmlc2&(cardiac&myosin&light&chain&2)&is&a&marker&of&heart&development&

Wloga&D&et&al.&(2009)&Dev&Cell&16:867_76&

A&tubulin&monoglycylase&is&required&for&proper&L_R&symmetry&breaking&

2.&&Dyneins&

Cilia&have&2&types&of&dyneins,&Cytoplasmic&and&Axonemal&•  Cytoplasmic&Dynein:&&this&is&a&large&(~1.5&Mda)&mul^subunit&motor&

protein&that&“walks”&along&microtubules,&and&carries&out&Retrograde&Intraflagellar&Transport&(IFT)&of&various&cargos&

hcps://www.youtube.com/watch?v=_7AQVbrmzFw&

•  Ciliary&(Axonemal)&Dynein&is&the&motor&that&bends&cilia&

~96nm&

Side&view&

Top&View&

(outer&dynein&arms)&

(Inner&dynein&arm)&

3.&&Kinesins& •  Anterograde&IFT&

hcps://www.youtube.com/watch?v=y_uuk4Pr2i8&

Mul^subunit&motor&proteins&that&“walk”&along&microtubules&toward&the&+&end&(anterograde)&and&deliver&cargos&(e.g.&tubulin,&dynein,&receptors)&to&the&cilia&^p.&

Ciliogenesis&

Ciliogenesis&commonly&occurs&as&cells&exit&the&cell&cycle&(Go).&&

Cilia&grow&out&of&the&basal&body,&&derived&from&the&mother&centriole.&&Posi^oning,&orienta^on,&and&docking&of&the&basal&body&are&^ghtly&regulated.&

Axonemes&are&ini^ated&by&adding&tubulin&subunits&to&the&distal&end&of&the&basal&body&and&then&extending&by&adding&tubulin&at&the&^p.&That&means&that&IFT&is&essen^al&for&ciliogenesis.&

Two&types&of&transcrip^on&factors,&the&RFX&family&and&FoxJ1,&are&involved&in&triggering&ciliogenesis.&

(in&the&lab,&starving&cells&by&limi^ng&serum&promotes&ciliogenesis)&

Direct and indirect targets of ciliary transcription factors.

Choksi S P et al. Development 2014;141:1427-1441

RFX'target'genes'

FoxJ1'target'genes'

Multiple pathways of ciliogenesis.

Dawe H R et al. J Cell Sci 2007;120:7-15

©2007 by The Company of Biologists Ltd

RFX&target&genes&are&required&for&mo^le&and&non_mo^le&cilia&

FoxJ1&target&genes&are&required&for&mo^le&cilia&

RFX&target&genes&are&required&for&docking&of&the&basal&body&to&the&apical&membrane&

Forming&mul^ple&cilia&involves&duplica^ng&centrioles&

Pihan&(2013)&Front.&Oncol.&3:277&

Structural&studies&and&microscopy&have&localized&many&centrosomal&proteins&

Some&of&these,&like&CEP164,&are&essen^al&for&docking&the&mother&centriole&to&the&&membrane&

PLK4,&a&kinase&involved&in&centriole&duplica^on&is&also&required&for&ciliogenesis.&One&target&is&TUBGCP6.&

Schmidt&et&al.&(2012)&J.&Cell&Biol.199:1083_1101&

Steps&of&Ciliogenesis&

DA=&Distal&Appendages&(Includes&CEP164)&

CEP164&is&required&for&docking&of&the&PCV&

0&

PCV=&Primary&Ciliary&Vessicle&

V=&2o&vessicles&fuse&with&the&PCV&&

1&

CB=&Ciliary&Bud.&&The&cap&protein&CP110&is&released&by&TTBK2&

2&

CiPo=&Ciliary&Pocket;&&invagina^on&of&the&PCV&

3&

AS=Axonemal&Sha{&

PM=Plasma&Membrane&4&

The&membrane&composi.on&of&the&ciliary&membrane&is&different&from&the&plasma&membrane.&&

What&determines&the&length&of&cilia?&

IFT&probably&has&a&lot&to&do&with&it&(rate&of&anterograde&assembly&versus&rate&of&retrograde&disassembly),&but&there&are&sure&to&be&other&factors...&

A&large&siRNA_based&screen&in&human&re^nal&pigmented&epithelial&cells&&iden^fied&expected&genes,&like&KIF3A&(no&cilia!),&a&kinesin&

Surprisingly,&deple^on&of&2&gelsolin_family&proteins&reduced&cilia&numbers.&&

gelsolin&regulates&ac^n&organiza^on&by&cleaving&ac^n&filaments&

Deple^on&of&an&ARP3&homolog,&which&is&required&for&ac^n&branching,&lengthened&cilia,&sugges^ng&that&branched&ac^n&networks&inhibit&ciliogenesis&

Kim&et&al,&(2010)&Nature&464:1048_51&&&&

Size&of&pools&of&precursors&

Is&there&a&connec^on&to&ac^n??&

NCBI Annotation: Confirmed negative ciliogenesis modulators (13 genes)

Entrez GeneID Official Symbol On Ciliome Gene Location General Protein Information 10096 ACTR3 - 2q14.1 [ARP3 actin-related protein 3 homolog] 55966 AJAP1 - 1p36.32 [adherens junction associated protein 1, OTTHUMP00000000694, OTTHUMP00000000695, transmembrane protein SHREW1] 25820 ARIH1 - 15q24 [ariadne ubiquitin-conjugating enzyme E2 binding protein homolog 1, ariadne, Drosophila, homolog of] 8727 CTNNAL1 - 9q31.2 [catenin, alpha-like 1, alpha-catulin, alpha2-catulin, OTTHUMP00000021872]

4281 MID1 - Xp22 [midline 1, OTTHUMP00000022896, OTTHUMP00000022898, OTTHUMP00000022900, OTTHUMP00000022901, midline 1 ring finger, tripartite motif protein TRIM18, putative transcription factor XPRF, zinc finger on X and Y, mouse, homolog of]

55742 PARVA - 11p15.3 [parvin, alpha, actopaxin, alpha-parvin, matrix-remodelling associated 2] 11187 PKP3 - 11p15 [plakophilin 3] 50487 PLA2G3 - 22q11.2-q13.2 [phospholipase A2, group III, group III secreted phospholipase A2, phosphatidylcholine 2-acylhydrolase GIII]

8613 PPAP2B - 1pter-p22.1 [phosphatidic acid phosphatase type 2B, OTTHUMP00000009855, lipid phosphate phosphohydrolase 3, phosphatidic acid phosphohydrolase 2b, type-2 phosphatidic acid phosphatase-beta, vascular endothelial growth factor and type I collagen inducible]

51422 PRKAG2 - 7q36.1 [AMP-activated protein kinase gamma2 subunit, AMPK gamma2] 29127 RACGAP1 - 12q13.13 [Rac GTPase activating protein 1, GTPase activating protein] 5998 RGS3 - 9q32 [regulator of G-protein signalling 3, OTTHUMP00000022813, OTTHUMP00000022814, OTTHUMP00000022815] 331 XIAP - Xq25 [baculoviral IAP repeat-containing protein 4, OTTHUMP00000023975, OTTHUMP00000196392, apoptosis inhibitor 3, baculoviral IAP repeat-containing 4]

Deple.on&of&PLA2G3&a&phospholipase,&lengthened&cilia,&sugges.ng&the&involvement&of&recycling&endocytosis&in&cilia&length&determina.on&

Kim&et&al,&(2010)&Nature&464:1048_51&&&&

Overexpressed&PLA2G3&inhibited&ciliogenesis.&

(phospholipases&have&been&proposed&to&induce&curvature&of&membranes,&and&may&be&indirectly&involved&in&endosome&trafficking)&&

Ciliopathies&

Human&Gene.cs&and&ciliopathies&

1.&&Primary&Ciliary&Dyskinesia&&(includes&Kartagener’s&Syndrome)&

2.&&Bardet_Biedl&Syndrome&

3.&&Joubert&Syndrome&

Others:&&Nephronophthisis&(Senior_Loken&syndrome);Polycys^c&Kidney&disease;&Re^ni^s&pigmentosa;&Alstrom&Syndrome;&OCRL,&etc.&

Afzelius&BA&(1976)&A&human&syndrome&caused&by&immo^le&cilia,&Science&193:317_9&

Kartagener’s&Syndrome:&&defec^ve&dynein&arms=&bronchial&infec^ons,&immobile&sperm,&situs&inversus&

Normal&Sperm& Pa^ent&(L.P.)&Sperm& Diagram&of&Normal&Sperm&

Zariwala,&Knowles,&and&Leigh,&(2009)&Gene&Reviews,&Copyright&©&1993_2011,&University&of&Washington,&Seacle.&&&

Primary&Ciliary&Dyskinesia&

1.&&Frequent&lung&infec^ons&

2.&&Male&infer^lity&

3.&When&accompanied&by&&Situs&

inversus&=&Kartegener’s&

4.&&Other,&variable&features:&&poor&sense&of&smell;&poor&hearing&

Cilia&mo^on&in&the&trachea'

hcp://visual.merriam_webster.com/human_being/anatomy/respiratory_system.php

Primary&Ciliary&Dyskinesia&affects&cilia&in&the&airway,&making&it&hard&to&clear&junk&out&of&the&lungs,&leading&to&frequent&lung&infec^ons&

Mo^le&&cilia&&are&generally&“9+2”&and&primary&cilia&are&generally&“9+0”&

Cardenas_Rodriguez&M,&Badano&JL.&2009.&Ciliary&biology:&Understanding&the&cellular&and&gene^c&basis&of&human&ciliopathies.&Am&J&Med&Genet&Part&C&Semin&Med&Genet&151C:263&–&280&

Review&

Muta.ons*&in&subunits&of&dynein,&or&components&of&the&axoneme,&or&assembly&factors&can&lead&to&immobile&cilia&

Zariwala&et&al.&(2011)Proc&Am&Thorac&Soc&8:430–433&&

*Interes^ngly,&this&is&an&autosomal&recessive&disorder&

DRC&=&Dynein&Regulatory&Center&

Situs&Inversus—What&is&it,&and&what’s&the&connec^on&to&cilia?&

hcp://en.academic.ru/dic.nsf/enwiki/336675&

How&is&LLR&asymmetry&established?&

Diego&Franco,&Jorge&N&Domínguez,&Amelia&Aránega.&

(Le{&lateral&plate&mesoderm)&(Right&lateral&plate&mesoderm)&

LeeLRight&Asymmetry:&clockwise&twirling&of&cilia&creates&a&RightLtoLLee&flow&across&&the&Node&

Okada&et&al.,&Cell&121,&pp.633_644

A& P&

L&

R&Macromolecules&>&~15&kDa&are&moved&along&the&current&

Okada&et&al.,&Cell&121,&pp.633_644

LeeLright&asymmetry&determined&by&currents&generated&by&cilia&&

Posteriorly&Tilted&Rota^on&of&Cilia&of&the&Mouse&Nodal&Pit

Okada&et&al.,&Cell&121,&pp.633_644

Nodal&cilia&establish&an&asymmetric&distribu.on&of&a&fluorescent&macromolecule&

Planar&Cell&Polarity&mechanisms&establish&the&orienta^on&and&angle&of&the&cilia&

Bardet_Biedl&Syndrome&Phenotype:&&postaxial&polydactyly,&mental&retarda^on,&hypogonadism,&renal&dysfunc^on,&re^nal&degenera^on,&situs&inversus,&obesity&&

Alexander&K.&C.&Leung,&MD&and&Reginald&S.&Sauve,&MD&|&Pediatrics&Consultant&LiveSeptember&14,&2005&

How&are&these&features&connected?&

This&was&a&key&publica^on&that&heralded&a&wave&of&publica^ons&collec^vely&describing&“ciliopathies”&

Count&the&toes!&

The&BBSome&

•  Discovered&by&Localiza^on&and&tandem&affinity&purifica^on&

GFP& BBS4&S_tag&

Nachury&et&al,&(2007)&Cell&129:1201_13&

7&BBS&proteins&co_purify&BBS5&binds&phospha^dyl&inositol&triphosphate&

Nature'425,&628_633(9&October&2003)&

GenotypeLPhenotype&correla.ons—BBS8&

Different'muta:ons'in'the'same'gene'can'cause'different'phenotypes'

BardetLBiedl&Syndrome:&&&obesity,&re^ni^s&pigmentosa,&polydactyly,&hypogonadism,&renal&disease&&&

15&different&genes,&and&coun^ng,&plus&some&modifier&genes&

some&clinical&features&overlap&with&other&diseases,&e.g.,&Meckel&Syndrome,&Alstrom&Syndrome&

Leroux&(2007)&Cell&129:1041_3&&

The&BBSome&is&an&integral&element&of&anterograde&IFT&

How&does&“Turnaround”&at&the&^p&of&the&cilia&happen?&

Defects&in&the&BBSome&could&affect&localiza^on&of&receptors.&&How&would&this&explain&some&of&the&phenotypes&of&BBS?&

Wei&et&al,&(2012)&Nat&Cell&Biol.&14:950_7&&

A&point&muta^on&in&BBS1&par:ally&impairs&binding&of&the&BBSome&to&IFT_A/B,&slowing&the&return&of&IFT&components&to&the&cytoplasm&by&retrograde&transport&

A&point&muta^on&in&DYF_2&par:ally&impairs&binding&of&the&BBSome&to&IFT_A/B,&slowing&the&return&of&IFT&components&to&the&cytoplasm&by&retrograde&transport&

Update:&&The&BBSome&is&involved&in&the&transi.on&between&anterograde&and&retrograde&IFT&

All&drawings&of&IFT&are&oversimplified!&

Much&of&Cilia&diversity&is&governed&by&IFT.&&What&governs&the&selec^vity&of&kinesins&for&cargo?&

How&do&you&keep&unwanted&cytoplasmic&proteins&from&entering&the&cilia?&

Silverman&and&Leroux&(2009)&19:306_16&

Ciliary&Targe^ng&Signal&(CTS)?&

Is&there&a&

Cilia&are&primary&Antennae&for&many&cells&

Many&receptors,&such&as&GPCRs,&are&preferen^ally&localized&to&cilia.&

•  Olfactory&receptors&

•  (Some)&Neuronal&receptors&(somatosta^n&receptor&3;&serotonin&receptor&6;&dopamine&receptors,&etc.&&

Omori&et&al.&looked&for&ciliary&localiza^on&of&138&GPCRs&in&brain,&but&only&found&12/138&that&were&reproducibly&ciliary.&&Kind&of&interes^ng,&although&a&bit&disappoin^ng…&

Omori&et&al.&PLoS&One.&2015;&10(6):&e0128422.&

Neurobiol&Dis.&2010&38:&167–172.&

Cilia&organize&several&signaling&receptors,&including&Patched&

…also&the&lep^n&receptor&

Joubert&Syndrome/Cerebrooculorenal&Syndrome&

Hypoplasia&of&cerebellar&vermis&(“molar&tooth&sign”),&re^nal&dysplasia&(blindness),&renal&disease.&&This&affects&balance&and&coordina^on&(hypotonia),&development,&and&cogni^ve&func^on.&&Features&can&be&variable&in&severity.&&Affected&genes&include&INPP5E,&TMEM216...&

Autosomal&recessive,&gene^cally&heterogeneous,&with&20&loci&iden^fied&(JBTS1_20).&&A&recently&described&muta^on&in&CEP41&affects&localiza^on&of&a&tubulin&glutamylase&(TTLL6)&to&cilia.&(Centrosomal&Protein&41)&

hcp://globalgenes.org&Lee&et&al&(2012)&Nat&Genet&44:193_9&Maria&et&al&(1999)&J&Child&Neurol&14:&583_591&

“Molar&Tooth&Sign”&

What’s&the&connec.on&with&mental&retarda.on?&

Cilia&are&antennae&for&sensing&the&environment&

Defects&in&cilia&disrupt&signaling&during&neural&development&

cerebellum&

hippocampus&

axonal&guidance&

The&primary&cilia&are&packed&with&receptors&(GPCRs,&etc.)&

Mo^le&cilia&circulate&cerebrospinal&fluid—recall&that&ependymal&cells&line&ventricles&

Another&example&of&signaling&in&primary&cilia&

Exosomes&are&a&hot&topic&right&now&

Do&cilia&release&exosomes&from&the&^ps?&

Model illustrating unidirectional trafficking of SAG1 during ciliary adhesion and signaling.SAG1* in resting cells is present at the cell periphery, with only small amounts in

cilia.

Muqing Cao et al. eLife Sciences 2015;4:e05242

Chlamydomonas&ma^ng&may&involve&release&of&exosomes&from&the&^ps&of&the&flagella.&

Other&groups&have&proposed&models&where&GPCRs&in&mammalian&cells&are&released&from&cilia&by&exosomes,&but&this&idea&needs&more&suppor^ng&evidence&(one&paper&was&retracted!)&

Cilia&and&Cancer&

Many&types&of&cancer&show&a&loss&of&cilia:& Prostate&Cancer&Reneal&Cell&Carcinoma&Pancrea^c&Cancer&Ovrian&Cancer&Melanoma&Breast&Cancer&

There&are&at&least&2&explana^ons:&1.&&Rapidly&prolifera^ng&cancer&cells&never&exit&the&cell&cycle&

2.&A&hallmark&of&cancer&is&genomic&instability&and&aneuplody,&which&is&a&hallmark&of&aberrant&mitoses;&this&could&result&from&defec^ve&centrosomes.&Defec^ve&centrosomes&may&be&impaired&for&ciliogenesis.&

In&addi^on&to&ORC&proteins&associated&with&centrosomes,&there&are&several&reports&of&DNA&repair&proteins&associated&with&centrosomes&

Centrosomes&and&DNA&Repair???&

Gen1&(resolvase)&FANCJ&(ICL&repair)&BRCA2&(HR)&BRCA1&(HR)&TopBP1&(DSB&repair)&NBS1&(end&resec^on)&Rad51&(HR)&Rad51&paralogs&(HR)&PARP1&(DDR)&ATM&(DDR&checkpoint)&ATR&(DDR&and&replica^on&checkpoint)&Chk2&(DDR&checkpoint)&

WHY?&

Main&Points&

•  Cilia&are&highly&complex&organelles&(300_600&proteins)&

•  Cilia&can&be&both&mo^le&or&non_mo^le&

•  The&ciliary&membrane&is&dis^nct&from&the&plasma&membrane.&This&allows&the&assembly&of&a&dis^nct&cell&signaling&environment,&with&specific&receptors&localized&to&the&ciliary&membrane&

•  Mo^le&cilia&are&required&for&cell&movement,&establishing&flow&over&a&surface,&or&clearance&of&par^cles&from&the&airway&

•  Many&human&gene^c&diseases,&“ciliopathies”,&are&caused&by&defects&in&either&ciliogenesis&or&ciliary&func^on&