Planar Cell Polarity Effector Research Articles

Structure of the metazoan Rab7 GEF complex Mon1–Ccz1–Bulli

The endosomal system of eukaryotic cells represents a central sorting and recycling compartment linked to metabolic signaling and the regulation of cell growth. Tightly controlled activation of Rab GTPases is required to establish the different domains of endosomes and lysosomes. In metazoans, Rab7 controls endosomal maturation, autophagy, and lysosomal function. It is activated by the guanine nucleotide exchange factor (GEF) complex Mon1-Ccz1-Bulli (MCBulli) of the tri-longin domain (TLD) family. While the Mon1 and Ccz1 subunits have been shown to constitute the active site of the complex, the role of Bulli remains elusive. We here present the cryo-electron microscopy (cryo-EM) structure of MCBulli at 3.2Å resolution. Bulli associates as a leg-like extension at the periphery of the Mon1 and Ccz1 heterodimers, consistent with earlier reports that Bulli does not impact the activity of the complex or the interactions with recruiter and substrate GTPases. While MCBulli shows structural homology to the related ciliogenesis and planar cell polarity effector (Fuzzy-Inturned-Wdpcp) complex, the interaction of the TLD core subunits Mon1-Ccz1 and Fuzzy-Inturned with Bulli and Wdpcp, respectively, is remarkably different. The variations in the overall architecture suggest divergent functions of the Bulli and Wdpcp subunits. Based on our structural analysis, Bulli likely serves as a recruitment platform for additional regulators of endolysosomal trafficking to sites of Rab7 activation.

Planar Cell Polarity Effector Fuzzy in Actin Regulation and Ciliogenesis

Planar Cell Polarity Effector Fuzzy in Actin Regulation and Ciliogenesis

Multifaceted investigation underlies diverse mechanisms contributing to the downregulation of Hedgehog pathway-associated genes INTU and IFT88 in lung adenocarcinoma and uterine corpus endometrial carcinoma.

Hedgehog (Hh) signaling primarily functions in the control of mammalian embryonic development but also has roles in cancer. The Hh activation depends on ciliogenesis, a cellular process that describes outgrowth of the primary cilium from cell membrane. Ciliogenesis initiation requires a set of proteins known as planar cell polarity (PCP) effectors. Inturned (INTU) is a PCP effector that reportedly functions synergistically with Hh signaling in basal cell carcinoma, suggesting that INTU has an oncogenic role. In this study, we carried out a pan-cancer investigation on the prognostic significance of INTU in different types of cancer. We demonstrated that INTU downregulation correlated with reduced survival probabilities in lung adenocarcinoma (LUAD) and uterine corpus endometrial carcinoma (UCEC) patients. Similar expression patterns and prognostic values were identified for intraflagellar transport 88 (IFT88), another Hh pathway-associated gene. We elucidated multiple mechanisms at transcriptional, post-transcriptional and translational levels that involved transcription factor 4 and non-coding RNAs-associated regulatory networks contributing to the reduction of INTU and IFT88 levels in LUAD and UCEC samples. Taken together, this study demonstrates the prognostic significance of the Hh-related genes INTU and IFT88 in LUAD and UCEC and further delineates multifaceted mechanisms leading to INTU and IFT88 downregulation in tumor samples.

Fuzzy Planar Cell Polarity Gene (FUZ) Promtes Cell Glycolysis, Migration, and Invasion in Non-small Cell Lung Cancer via the Phosphoinositide 3-Kinase/Protein Kinase B Pathway.

Purpose: Fuzzy planar cell polarity gene (FUZ) is regarded as a planar cell polarity effector that controls multiple cellular processes during vertebrate development. The role of FUZ in glucose metabolism, invasion, and metastasis of non-small cell lung cancer (NSCLC) is unclear. The aims of this study were to investigate the relationship between FUZ and glucose metabolism and its mechanism of action.Materials and methods: Quantitative real-time polymerase chain reaction (qRT-PCR) analysis was used to detect FUZ expression in A549 and H1299 cells. Additionally, qRT-PCR and western blot analysis were used to detect the expression of related glucose metabolism indicators, and lactate and 18 Fluorine fludeoxyglucose (18F-FDG) uptake assays used to detect changes in glucose metabolites. Further, cell invasion and migration behavior were evaluated by transwell and wound healing assays. In vivo tumor growth assay was conducted to assess the effect of FUZ.Results: We found that FUZ was significantly upregulated in the NSCLC cell lines compared to that in the normal HBE cells. FUZ was found to promote energy metabolism through the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway, and overexpression of FUZ increased both lactic acid and 18F-FDG uptake. Moreover, FUZ knockdown significantly inhibited the migration and invasion of NSCLC cells. In vivo, FUZ knockdown can significantly inhibit tumor proliferation in the xenograft model, which was well identified by Micro-PET scan.Conclusion: The present finding in vitro and vivo show that FUZ is involved in NSCLC cell energy metabolism, invasion and migration via the PI3K/AKT signaling pathway, suggesting that FUZ can be a potential therapeutic target for NSCLC.

Loss of Planar Cell Polarity Effector Fuzzy Causes Renal Hypoplasia by Disrupting Several Signaling Pathways.

In vertebrates, the planar cell polarity (PCP) pathway regulates tissue morphogenesis during organogenesis, including the kidney. Mutations in human PCP effector proteins have been associated with severe syndromic ciliopathies. Importantly, renal hypoplasia has been reported in some patients. However, the developmental disturbance that causes renal hypoplasia is unknown. Here, we describe the early onset of profound renal hypoplasia in mice homozygous for null mutation of the PCP effector gene, Fuzzy. We found that this phenotype is caused by defective branching morphogenesis of the ureteric bud (UB) in the absence of defects in nephron progenitor specification or in early steps of nephrogenesis. By using various experimental approaches, we show that the loss of Fuzzy affects multiple signaling pathways. Specifically, we found mild involvement of GDNF/c-Ret pathway that drives UB branching. We noted the deficient expression of molecules belonging to the Bmp, Fgf and Shh pathways. Analysis of the primary cilia in the UB structures revealed a significant decrease in ciliary length. We conclude that renal hypoplasia in the mouse Fuzzy mutants is caused by defective UB branching associated with dysregulation of ciliary and non-ciliary signaling pathways. Our work suggests a PCP effector-dependent pathogenetic mechanism that contributes to renal hypoplasia in mice and humans.

Loss of Zic3 impairs planar cell polarity leading to abnormal left-right signaling, heart defects and neural tube defects.

Loss of function of ZIC3 causes heterotaxy (OMIM #306955), a disorder characterized by organ laterality defects including complex heart defects. Studies using Zic3 mutant mice have demonstrated that loss of Zic3 causes heterotaxy due to defects in establishment of left-right (LR) signaling, but the mechanistic basis for these defects remains unknown. Here, we demonstrate Zic3 null mice undergo cilia positioning defects at the embryonic node consistent with impaired planar cell polarity (PCP). Cell-based assays demonstrate that ZIC3 must enter the nucleus to regulate PCP and identify multiple critical ZIC3 domains required for regulation of PCP signaling. Furthermore, we show that Zic3 displays a genetic interaction with the PCP membrane protein Vangl2 and the PCP effector genes Rac1 and Daam1 resulting in increased frequency and severity of neural tube and heart defects. Gene and protein expression analyses indicate that Zic3 null embryos display disrupted expression of PCP components and reduced phosphorylation of the core PCP protein DVL2 at the time of LR axis determination. These results demonstrate that ZIC3 interacts with PCP signaling during early development, identifying a novel role for this transcription factor, and adding additional evidence about the importance of PCP function for normal LR patterning and subsequent heart development.

WDPCP Modulates Cilia Beating Through the MAPK/ERK Pathway in Chronic Rhinosinusitis With Nasal Polyps.

Cilia loss and dysfunction is one of the typical pathological features of chronic rhinosinusitis with nasal polyps (CRSwNP). Tryptophan-aspartic acid (W-D) repeat containing planar cell polarity effector (WDPCP) has been proven to be an essential element for ciliogenesis in human nasal epithelium, but its role in the beating of cilia remains unclear. In this study, we sought to investigate the role of WDPCP and its underlying mechanism behind the dysfunction in the beating of cilia in nasal polyp tissue. We demonstrated WDPCP expression in the epithelium of nasal polyps. We also investigated the MAPK/ERK pathway in primary human sinonasal epithelial cells to explore the function of WDPCP. The air–liquid interface culture system was used as a model to verify the role of WDPCP and the MAPK/ERK pathway in the beating of cilia. With the dysfunction of cilia beating, we observed a low expression of WDPCP in the epithelium of nasal polyp tissues. Within the in vitro study, we found that WDPCP was critical for mitochondrial biogenesis and mitochondrial function in human sinonasal epithelial cells, possibly due to the activation of the MAPK/ERK pathway. The mitochondrial dysfunction caused by U0126 or lacking WDPCP could be partially recovered by dexamethasone. The low expression of WDPCP in nasal epithelium could affect mitochondria via the MAPK/ERK pathway, which may contribute to the dysfunction in the beating of cilia in CRSwNP.

Planar Cell Polarity Effector Proteins Inturned and Fuzzy Form a Rab23 GEF Complex.

SummaryA subset of Rab GTPases have been implicated in cilium formation in cultured mammalian cells [1, 2, 3, 4, 5, 6]. Rab11 and Rab8, together with their GDP-GTP exchange factors (GEFs), TRAPP-II and Rabin8, promote recruitment of the ciliary vesicle to the mother centriole and its subsequent maturation, docking, and fusion with the cell surface [2, 3, 4, 5]. Rab23 has been linked to cilium formation and membrane trafficking at mature cilia [1, 7, 8]; however, the identity of the GEF pathway activating Rab23, a member of the Rab7 subfamily of Rabs, remains unclear. Longin-domain-containing complexes have been shown to act as GEFs for Rab7 subfamily GTPases [9, 10, 11, 12]. Here, we show that Inturned and Fuzzy, proteins previously implicated as planar cell polarity (PCP) effectors and in developmentally regulated cilium formation [13, 14], contain multiple longin domains characteristic of the Mon1-Ccz1 family of Rab7 GEFs and form a specific Rab23 GEF complex. In flies, loss of Rab23 function gave rise to defects in planar-polarized trichome formation consistent with this biochemical relationship. In cultured human and mouse cells, Inturned and Fuzzy localized to the basal body and proximal region of cilia, and cilium formation was compromised by depletion of either Inturned or Fuzzy. Cilium formation arrested after docking of the ciliary vesicle to the mother centriole but prior to axoneme elongation and fusion of the ciliary vesicle and plasma membrane. These findings extend the family of longin domain GEFs and define a molecular activity linking Rab23-regulated membrane traffic to cilia and planar cell polarity.

Planar cell polarity signaling regulates polarized second heart field morphogenesis to promote both arterial and venous pole septation.

The second heart field (SHF) harbors progenitors that are important for heart formation, but little is known about its morphogenesis. We show that SHF population in the mouse splanchnic mesoderm (SpM-SHF) undergoes polarized morphogenesis to preferentially elongate anteroposteriorly. Loss of Wnt5, a putative ligand of the planar cell polarity (PCP) pathway, causes the SpM-SHF to expand isotropically. Temporal tracking reveals that the Wnt5a lineage is a unique subpopulation specified as early as E7.5, and undergoes bi-directional deployment to form specifically the pulmonary trunk and the dorsal mesenchymal protrusion (DMP). In Wnt5a-/- mutants, Wnt5a lineage fails to extend into the arterial and venous poles, leading to both outflow tract and atrial septation defects that can be rescued by an activated form of PCP effector Daam1. We identify oriented actomyosin cables in the medial SpM-SHF as a potential Wnt5a-mediated mechanism that promotes SpM-SHF lengthening and restricts its widening. Finally, the Wnt5a lineage also contributes to the pulmonary mesenchyme, suggesting that Wnt5a/PCP is a molecular circuit recruited by the recently identified cardiopulmonary progenitors to coordinate morphogenesis of the pulmonary airways and the cardiac septations necessary for pulmonary circulation.This article has an associated 'The people behind the papers' interview.

Planar cell polarity gene Fuz triggers apoptosis in neurodegenerative disease models.

Planar cell polarity (PCP) describes a cell-cell communication process through which individual cells coordinate and align within the plane of a tissue. In this study, we show that overexpression of Fuz, a PCP gene, triggers neuronal apoptosis via the dishevelled/Rac1 GTPase/MEKK1/JNK/caspase signalling axis. Consistent with this finding, endogenous Fuz expression is upregulated in models of polyglutamine (polyQ) diseases and in fibroblasts from spinocerebellar ataxia type 3 (SCA3) patients. The disruption of this upregulation mitigates polyQ-induced neurodegeneration in Drosophila We show that the transcriptional regulator Yin Yang 1 (YY1) associates with the Fuz promoter. Overexpression of YY1 promotes the hypermethylation of Fuz promoter, causing transcriptional repression of Fuz Remarkably, YY1 protein is recruited to ATXN3-Q84 aggregates, which reduces the level of functional, soluble YY1, resulting in Fuz transcriptional derepression and induction of neuronal apoptosis. Furthermore, Fuz transcript level is elevated in amyloid beta-peptide, Tau and α-synuclein models, implicating its potential involvement in other neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. Taken together, this study unveils a generic Fuz-mediated apoptotic cell death pathway in neurodegenerative disorders.

In vitro study of FUZ as a novel potential therapeutic target in non-small-cell lung cancer

FUZ is regarded as a planar cell polarity effector that controls multiple cellular processes during vertebrate development. However, the role of FUZ in tumor biology remains poorly studied. Our purpose of this study is to discover the physiological effects and mechanism of FUZ in non-small-cell lung cancer (NSCLC) in vitro. With the help of bioinformatics analysis, we noticed that the expression level of FUZ negatively correlates with prognosis of NSCLC patients. Exogenous FUZ expression markedly promoted cell proliferation of NSCLC cells. The phosphorylation of Erk1/2, STAT3 and related signaling molecules were induced activated after FUZ over-expression. FUZ also plays an important role in cell motility by regulating cell signaling pathways and inducing epithelial to mesenchymal transition (EMT). FUZ promotes EMT along with the up-regulation of N-cadherin, vimentin, Zeb1, Twist1 and decreased level of E-cadherin. Furthermore, we also carried out FUZ directed siRNA treatments to prove the above observations. Knockdown of FUZ resulted in delayed cell growth as well as impaired cell migration and reversed EMT phonotype. Importantly, we reported for the first time that FUZ is a BNIP3-interacting protein. Loss of FUZ resulted in decreased BNIP3 protein level, but no influence on BNIP3 mRNA level, suggesting weakened stability of BNIP3 protein. Overall, our results in vitro show that FUZ is responsible for NSCLC progression and metastasis, suggesting that FUZ can be a potential therapeutic target for NSCLC.

Planar Cell Polarity Effector Fritz Interacts with Dishevelled and Has Multiple Functions in Regulating PCP.

The Planar cell Polarity Effector (PPE) genes inturned, fuzzy, and fritz are downstream components in the frizzled/starry night signaling pathway, and their function is instructed by upstream Planar Cell Polarity (PCP) core genes such as frizzled and dishevelled. PPE proteins accumulate asymmetrically in wing cells and function in a protein complex mediated by direct interactions between In and Frtz and In and Fy. How the PCP proteins instruct the accumulation of PPE protein is unknown. We found a likely direct interaction between Dishevelled and Fritz and Dishevelled and Fuzzy that could play a role in this. We previously found that mild overexpression of frtz rescued a weak in allele. To determine if this was due to extra Frtz stabilizing mutant In or due to Frtz being able to bypass the need for In we generate a precise deletion of the inturned gene (inPD). We found that mild overexpression of Fritz partially rescued inPD, indicating that fritz has In independent activity in PCP. Previous studies of PPE proteins used fixed tissues, and did not provide any insights into the dynamic properties of PPE proteins. We used CRISPR/Cas9 genome editing technology to edit the fritz gene to add a green fluorescent protein tag. fritzmNeonGreen provides complete rescue activity and works well for in vivo imaging. Our data showed that Fritz is very dynamic in epidermal cells and preferentially distributed to discrete membrane subdomains (“puncta”). Surprisingly, we found it in stripes in developing bristles.

The GPSM2/LGN GoLoco motifs are essential for hearing

The planar cell polarity (PCP) pathway is responsible for polarizing and orienting cochlear hair cells during development through movement of a primary cilium, the kinocilium. GPSM2/LGN, a mitotic spindle-orienting protein associated with deafness in humans, is a PCP effector involved in kinocilium migration. Here, we link human and mouse truncating mutations in the GPSM2/LGN gene, both leading to hearing loss. The human variant, p.(Trp326*), was identified by targeted genomic enrichment of genes associated with deafness, followed by massively parallel sequencing. Lgn (ΔC) mice, with a targeted deletion truncating the C-terminal GoLoco motifs, are profoundly deaf and show misorientation of the hair bundle and severe malformations in stereocilia shape that deteriorates over time. Full-length protein levels are greatly reduced in mutant mice, with upregulated mRNA levels. The truncated Lgn (ΔC) allele is translated in vitro, suggesting that mutant mice may have partially functioning Lgn. Gαi and aPKC, known to function in the same pathway as Lgn, are dependent on Lgn for proper localization. The polarization of core PCP proteins is not affected in Lgn mutants; however, Lgn and Gαi are misoriented in a PCP mutant, supporting the role of Lgn as a PCP effector. The kinocilium, previously shown to be dependent on Lgn for robust localization, is essential for proper localization of Lgn, as well as Gαi and aPKC, suggesting that cilium function plays a role in positioning of apical proteins. Taken together, our data provide a mechanism for the loss of hearing found in human patients with GPSM2/LGN variants.

The planar cell polarity effector protein Wdpcp (Fritz) controls epithelial cell cortex dynamics via septins and actomyosin

Planar cell polarity (PCP) signaling controls polarized behaviors in diverse tissues, including the collective cell movements of gastrulation and the planar polarized beating of motile cilia. A major question in PCP signaling concerns the mechanisms linking this signaling cascade with more general cytoskeletal elements to drive polarized behavior. Previously, we reported that the PCP effector protein Wdpcp (formerly known as Fritz) interacts with septins and is critical for collective cell migration and cilia formation. Here, we report that Wdpcp is broadly involved in maintaining cortical tension in epithelial cells. In vivo 3D time-lapse imaging revealed that Wdpcp is necessary for basolateral plasma membrane stability in epithelial tissues, and we further show that Wdpcp controls cortical septin localization to maintain cortical rigidity in mucociliary epithelial cells. Finally, we show that Wdpcp acts via actomyosin to maintain balanced cortical tension in the epithelium. These data suggest that, in addition to its role in controlling plasma membrane dynamics in collective mesenchymal cell movements, Wdpcp is also essential for normal cell cortex stability during epithelial homeostasis.

Combover/CG10732, a Novel PCP Effector for Drosophila Wing Hair Formation

The polarization of cells is essential for the proper functioning of most organs. Planar Cell Polarity (PCP), the polarization within the plane of an epithelium, is perpendicular to apical-basal polarity and established by the non-canonical Wnt/Fz-PCP signaling pathway. Within each tissue, downstream PCP effectors link the signal to tissue specific readouts such as stereocilia orientation in the inner ear and hair follicle orientation in vertebrates or the polarization of ommatidia and wing hairs in Drosophila melanogaster. Specific PCP effectors in the wing such as Multiple wing hairs (Mwh) and Rho Kinase (Rok) are required to position the hair at the correct position and to prevent ectopic actin hairs. In a genome-wide screen in vitro, we identified Combover (Cmb)/CG10732 as a novel Rho kinase substrate. Overexpression of Cmb causes the formation of a multiple hair cell phenotype (MHC), similar to loss of rok and mwh. This MHC phenotype is dominantly enhanced by removal of rok or of other members of the PCP effector gene family. Furthermore, we show that Cmb physically interacts with Mwh, and cmb null mutants suppress the MHC phenotype of mwh alleles. Our data indicate that Cmb is a novel PCP effector that promotes to wing hair formation, a function that is antagonized by Mwh.

SCRIB and PUF60 Are Primary Drivers of the Multisystemic Phenotypes of the 8q24.3 Copy-Number Variant

Copy-number variants (CNVs) represent a significant interpretative challenge, given that each CNV typically affects the dosage of multiple genes. Here we report on five individuals with coloboma, microcephaly, developmental delay, short stature, and craniofacial, cardiac, and renal defects who harbor overlapping microdeletions on 8q24.3. Fine mapping localized a commonly deleted 78 kb region that contains three genes: SCRIB, NRBP2, and PUF60. Invivo dissection of the CNV showed discrete contributions of the planar cell polarity effector SCRIB and the splicing factor PUF60 to the syndromic phenotype, and the combinatorial suppression of both genes exacerbated some, but not all, phenotypic components. Consistent with these findings, we identified an individual with microcephaly, short stature, intellectual disability, and heart defects with a de novo c.505C>T variant leading to a p.His169Tyr change in PUF60. Functional testing of this allele invivo and invitro showed that the mutation perturbs the relative dosage of two PUF60 isoforms and, subsequently, the splicing efficiency of downstream PUF60 targets. These data inform the functions of two genes not associated previously with human genetic disease and demonstrate how CNVs can exhibit complex genetic architecture, with the phenotype being the amalgam of both discrete dosage dysfunction of single transcripts and also of binary genetic interactions.

The Small GTPase Rsg1 is important for the cytoplasmic localization and axonemal dynamics of intraflagellar transport proteins

BackgroundCilia are small, microtubule-based protrusions important for development and homeostasis. We recently demonstrated that the planar cell polarity effector protein Fuz is a critical regulator of axonemal intraflagellar transport dynamics and localization. Here, we report our findings on the role of the small GTPase Rsg1, a known binding partner of Fuz, and its role in the dynamics and cytoplasmic localization of intraflagellar transport proteins.ResultsWe find that Rsg1 loss of function leads to impaired axonemal IFT dynamics in multiciliated cells. We further show that Rsg1 is required for appropriate cytoplasmic localization of the retrograde IFT-A protein IFT43. Finally, we show that Rsg1 governs the apical localization of basal bodies, the anchoring structures of cilia.ConclusionsOur data suggest that Rsg1 is a regulator of multiple aspects of ciliogenesis, including apical trafficking of basal bodies and the localization and dynamics intraflagellar transport proteins.

The PCP effector Fuzzy controls cilial assembly and signaling by recruiting Rab8 and Dishevelled to the primary cilium

The planar cell polarity (PCP) pathway controls multiple cellular processes during vertebrate development. Recently the PCP pathway was implicated in ciliogenesis and in ciliary function. The primary cilium is an apically projecting solitary organelle that is generated via polarized intracellular trafficking. Because it acts as a signaling nexus, defects in ciliogenesis or cilial function cause multiple congenital anomalies in vertebrates. Loss of the PCP effector Fuzzy affects PCP signaling and formation of primary cilia; however, the mechanisms underlying these processes are largely unknown. Here we report that Fuzzy localizes to the basal body and ciliary axoneme and is essential for ciliogenesis by delivering Rab8 to the basal body and primary cilium. Fuzzy appears to control subcellular localization of the core PCP protein Dishevelled, recruiting it to Rab8-positive vesicles and to the basal body and cilium. We show that loss of Fuzzy results in inhibition of PCP signaling and hyperactivation of the canonical WNT pathway. We propose a mechanism by which Fuzzy participates in ciliogenesis and affects both canonical WNT and PCP signaling.

Planar cell polarity, cilia, and human disease

The planar cell polarity (PCP) proteins govern diverse cellular behaviors, are essential for embryonic development, and are associated in a variety of human birth defects, including ciliopathies. While many PCP proteins have been extensively characterized, the “PCP effector” proteins, Inturned, Fuzzy and Fritz, remain largely unstudied. We have shown that each of these novel proteins is broadly essential for ciliogenesis in vertebrate animals. Here, we will discuss our efforts to combine bioinformatics, genomics, mouse genetics, and in vivo time-lapse imaging of intraflagellar transport to understand the mechanisms by which the PCP proteins govern cilia structure and function.

Investigating the link between PCP signalling and ciliogenesis during zebrafish development

Polycystic kidney disease (PKD) is characterized by dilated collecting tubules causing fluid filled cysts and enlarged kidneys. Dilated tubules can result from disrupted convergence and extension (C&E) movements and defects in oriented cell divisions (OCD). Planar cell polarity (PCP) signalling has been implicated in PKD since defects in C&E and OCD are both characteristic of disrupted PCP. Surprisingly, genetic studies of mutations causing PKD predominantly affect proteins that localize near cilia and basal bodies. The functional relationship between cilia and PCP signalling in the context of PKD is still poorly understood. Previous studies of PCP effector proteins suggested that PCP signalling was required for cilia formation. However, these proteins are not specific to PCP signalling and are shared with other Wnt pathways. To determine the role of a core and specific PCP regulator on ciliogenesis, we examined maternal-zygotic (MZ) vangl2 zebrafish mutants. Analysis of MZvangl2 mutants revealed that PCP is not required for cilia formation but is required for the posterior tilting and posterior positioning of motile cilia. To determine whether cilia were required to establish cell polarity, we generated MZift88 mutants where ciliogenesis is completely abolished. MZift88 mutants have normal C&E movements, suggesting that cilia are not directly required for PCP mediated morphogenetic movements. However, we have observed defects in PCP-controlled OCD occurring during gastrulation. Remarkably, these divisions occur prior to cilia formation, suggesting a cilia-independent role for IFT proteins in cell divisions. We are currently determining whether IFT88 regulates all OCD or just those that are PCP-controlled.