Altered centriolar cohesion by CEP250 and appendages impact outcome of patients with pancreatic cancer.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is one of the leading cause of cancer death worldwide. PDACs are characterized by centrosome aberrations, but whether centrosome-related genes influence patient outcomes has not been tested. METHODS: Publicly available RNA-sequencing data of patients diagnosed with PDAC were interrogated with unsupervised approaches to identify centrosome protein-encoding genes with prognostic relevance. Candidate genes were validated by immunohistochemistry and multiplex immunofluorescence in a set of clinical PDAC and normal pancreatic tissues. RESULTS: Results showed that two genes CEP250 and CEP170, involved in centrosome linker and centriolar subdistal appendages, were expressed at high levels in PDAC tissues and were correlated with prognosis of PDAC patients in independent databases. Large clustered γ-tubulin-labelled centrosomes were linked together by aberrant circular and planar-shaped CEP250 arrangements in CEP250-high expressing PDACs. Furthermore, PDACs displayed prominent centrosome separation and reduced CEP164-centrosomal labelling associated with acetylated-tubulin staining compared to normal pancreatic tissues. Interestingly, in a small validation cohort, CEP250-high expressing patients had shorter disease free- and overall-survival and almost none of those who received gemcitabine plus nab-paclitaxel first-line therapy achieved a clinical response. In contrast, weak CEP250 expression was associated with long-term survivors or responses to medical treatments. CONCLUSIONS: Alteration of the centriolar cohesion and appendages has effect on the survival of patients with PDAC.

CEP164-GLI2 association ensures the hedgehog signaling in pancreatic cancer cells.

Hedgehog (Hh) signaling is involved in multiple biological events including development and cancers. It is processed through primary cilia, which are assembled from the mother centriole in most mammalian cells. Pancreatic ductal adenocarcinoma (PDAC) cells generally lose their primary cilia; thus, the Hh signaling pathway is postulated to be independent of the organelle in PDAC. We previously reported that the mother centriole-specific protein, centrosomal protein 164 (CEP164), is required for centriolar localization of the GLI2 transcription factor in Hh signaling and for suppressing the expression of Hh-target genes. In this study, we demonstrated the physical interaction between CEP164 and GLI2, and delineated their binding modes at the mother centriole. The ectopically expressed GLI2-binding region of CEP164 reduced the centriolar GLI2 localization and enhanced the expression of Hh-target genes in PDAC cells. Furthermore, similar phenotypes were observed in PDAC cells lacking primary cilia. These results suggest that the CEP164-GLI2 association at the mother centriole is responsible for controlling Hh signaling, independent of primary cilia in PDAC cells.

Biallelic variants in CEP164 cause a motile ciliopathy-like syndrome.

Ciliopathies may be classed as primary or motile depending on the underlying ciliary defect and are usually considered distinct clinical entities. Primary ciliopathies are associated with multisystem syndromes typically affecting the brain, kidney, and eye, as well as other organ systems such as the liver, skeleton, auditory system, and metabolism. Motile ciliopathies are a heterogenous group of disorders with defects in specialised motile ciliated tissues found within the lung, brain, and reproductive system, and are associated with primary ciliary dyskinesia, bronchiectasis, infertility and rarely hydrocephalus. Primary and motile cilia share defined core ultra-structures with an overlapping proteome, and human disease phenotypes can reflect both primary and motile ciliopathies. CEP164 encodes a centrosomal distal appendage protein vital for primary ciliogenesis. Human CEP164 mutations are typically described in patients with nephronophthisis-related primary ciliopathies but have also been implicated in motile ciliary dysfunction. Here we describe a patient with an atypical motile ciliopathy phenotype and biallelic CEP164 variants. This work provides further evidence that CEP164 mutations can contribute to both primary and motile ciliopathy syndromes, supporting their functional and clinical overlap, and informs the investigation and management of CEP164 ciliopathy patients.

Expanding the genetic landscape of oral-facial-digital syndrome with two novel genes.

Oral-facial-digital syndromes (OFDS) are a heterogeneous and rare group of Mendelian disorders characterized by developmental abnormalities of the oral cavity, face, and digits caused by dysfunction of the primary cilium, a mechanosensory organelle that exists atop most cell types that facilitates organ patterning and growth. OFDS is inherited both in an X-linked dominant, X-linked recessive, and autosomal recessive manner. Importantly, though many of the causal genes for OFDS have been identified, up to 40% of OFD syndromes are of unknown genetic basis. Here we describe three children with classical presentations of OFDS including lingual hamartomas, polydactyly, and characteristic facial features found by exome sequencing to harbor variants in causal genes not previously associated with OFDS. We describe a female with hypothalamic hamartoma, urogenital sinus, polysyndactyly, and multiple lingual hamartomas consistent with OFDVI with biallelic pathogenic variants in CEP164, a gene associated with ciliopathy-spectrum disease, but never before with OFDS. We additionally describe two unrelated probands with postaxial polydactyly, multiple lingual hamartomas, and dysmorphic features both found to be homozygous for an identical TOPORS missense variant, c.29 C>A; (p.Pro10Gln). Heterozygous TOPORS pathogenic gene variants are associated with autosomal dominant retinitis pigmentosa, but never before with syndromic ciliopathy. Of note, both probands are of Dominican ancestry, suggesting a possible founder allele.

Roscovitine blocks collecting duct cyst growth in Cep164-deficient kidneys.

Nephronophthisis is an autosomal recessive kidney disease with high genetic heterogeneity. Understanding the functions of the individual genes contributing to this disease is critical for delineating the pathomechanisms of this disorder. Here, we investigated kidney function of a novel gene associated with nephronophthisis, CEP164, coding a centriolar distal appendage protein, using a Cep164 knockout mouse model. Collecting duct-specific deletion of Cep164 abolished primary cilia from the collecting duct epithelium and led to rapid postnatal cyst growth in the kidneys. Cell cycle and biochemical studies revealed that tubular hyperproliferation is the primary mechanism that drives cystogenesis in the kidneys of these mice. Administration of roscovitine, a cell cycle inhibitor, blocked cyst growth in the cortical collecting ducts and preserved kidney parenchyma in Cep164 knockout mice. Thus, our findings provide evidence that therapeutic modulation of cell cycle activity can be an effective approach to prevent cyst progression in the kidney.

CEP164-null cells generated by genome editing show a ciliation defect with intact DNA repair capacity.

Primary cilia are microtubule structures that extend from the distal end of the mature, mother centriole. CEP164 is a component of the distal appendages carried by the mother centriole that is required for primary cilium formation. Recent data have implicated CEP164 as a ciliopathy gene and suggest that CEP164 plays some roles in the DNA damage response (DDR). We used reverse genetics to test the role of CEP164 in the DDR. We found that conditional depletion of CEP164 in chicken DT40 cells using an auxin-inducible degron led to no increase in sensitivity to DNA damage induced by ionising or ultraviolet irradiation. Disruption of CEP164 in human retinal pigmented epithelial cells blocked primary cilium formation but did not affect cellular proliferation or cellular responses to ionising or ultraviolet irradiation. Furthermore, we observed no localisation of CEP164 to the nucleus using immunofluorescence microscopy and analysis of multiple tagged forms of CEP164. Our data suggest that CEP164 is not required in the DDR.

GPC2 as a diagnostic and prognostic marker regulated progression of colorectal cancer.

BACKGROUND AND STUDY AIMS: Glypican 2 (GPC2) is a member of the glypican gene family and is expressed in multiple kinds of cancer. However, the function and mechanism of GPC2 in colorectal cancer remains unclear. In this study, we aimed to identify the role of GPC2 on tumor cell proliferation and survival in colorectal cancer. PATIENTS AND METHODS: Ten pairs of colon cancer and matched normal colon tissues were collected in this research. GEPIA was used to analysis the GPC2 gene expression profile in TGCA data base. RT-qPCR and western blot assay were performed to determine the mRNA and protein expressions. CCK-8, Flow cytometry and colon formation assay were applied to evaluate cell viability. IHC staining was performed to evaluate the protein expression in tissues. The function of GPC2 in vivo was verified by an animal model of colon cancer. RESULTS: Through the bioinformatics analysis and qRT-PCR validation, we found that GPC2 was upregulated in the colon cancer tissues and cells. GPC2 knockdown suppressed cell proliferation in vitro and in vivo was confirmed by the results of CCK-8, colony formation assays, and tumor xenograft models. Moreover, by the analysis of flow cytometry assay and gain-or-loss function experiments, we discovered that CEP164 was highly associated with the expression state of GPC2, and mediated G2/M-phase arrest in GPC2-downregulated tumor cells. CONCLUSION: GPC2 might be a novel oncogenic gene in colorectal cancer, suggesting that it could be a considerable marker for the diagnosis and prognosis of colorectal cancer.

Drosophila transition fibers are essential for IFT-dependent ciliary elongation but not basal body docking and ciliary budding.

Cilia are highly conserved organelles critical for animal development and perception. Dysfunction of cilia has been linked to a wide spectrum of human genetic diseases, termed ciliopathies.1,2 Transition fibers (TFs) are striking ciliary base structures essential for cilia assembly. Vertebrates' TFs that originate from centriole distal appendages (DAs) mediate basal body docking to ciliary vesicles to initiate ciliogenesis and regulate the entry of ciliary proteins for axoneme assembly via intraflagellar transport (IFT) machinery.3 Although no distal appendages can be observed on Drosophila centrioles,4,5 three key TF proteins, FBF1, CEP164, and CEP89, have obvious homologs in Drosophila. We aimed to compare their functions with their mammalian counterparts in Drosophila ciliogenesis. Here, we show that all three proteins are localized like TF proteins at the ciliary base in both sensory neurons and spermatocytes, the only two types of ciliated cells in flies. Fbf1 and Cep89 are essential for the formation of IFT-dependent neuronal cilia, but Cep164 is dispensable for ciliogenesis in flies. Strikingly, none are required for basal body docking and transition zone (TZ) assembly in IFT-dependent neuronal cilia or IFT-independent spermatocyte cilia. Furthermore, we demonstrate that Unc is essential to recruit all three TF proteins and establish a hierarchical order, with Cep89 acting on Fbf1. Collectively, our results not only demonstrate that TF proteins are required for IFT-dependent ciliogenesis in Drosophila, in agreement with an evolutionarily conserved function of these proteins in regulating ciliary protein entry, but also that the basal body docking function of TFs has diverged during evolution.

Molecular mechanisms underlying the role of the centriolar CEP164-TTBK2 complex in ciliopathies.

Cilia formation is essential for human life. One of the earliest events in the ciliogenesis program is the recruitment of tau-tubulin kinase 2 (TTBK2) by the centriole distal appendage component CEP164. Due to the lack of high-resolution structural information on this complex, it is unclear how it is affected in human ciliopathies such as nephronophthisis. Furthermore, it is poorly understood if binding to CEP164 influences TTBK2 activities. Here, we present a detailed biochemical, structural, and functional analysis of the CEP164-TTBK2 complex and demonstrate how it is compromised by two ciliopathic mutations in CEP164. Moreover, we also provide insights into how binding to CEP164 is coordinated with TTBK2 activities. Together, our data deepen our understanding of a crucial step in cilia formation and will inform future studies aimed at restoring CEP164 functionality in a debilitating human ciliopathy.

Sustained glymphatic transport and impaired drainage to the nasal cavity observed in multiciliated cell ciliopathies with hydrocephalus.

BACKGROUND: Hydrocephalus (increased ventricular size due to CSF accumulation) is a common finding in human ciliopathies and in mouse models with genetic depletion of the multiciliated cell (MCC) cilia machinery. However, the contribution of MCC to CSF dynamics and, the mechanism by which impaired MCC function leads to hydrocephalus remains poorly understood. The aim of our study was to examine if defects in MCC ciliogenesis and cilia-generated CSF flow impact central nervous system (CNS) fluid homeostasis including glymphatic transport and solute waste drainage. METHODS: We used two distinct mouse models of MCC ciliopathy: MCC-specific CEP164 conditional knockout mice (FOXJ1-Cre;CEP164fl/fl (N = 10), 3-month-old) and p73 knock-out (p73-/- (N = 8), 5-month-old) mice. Age-matched, wild-type littermates for each of the mutants served as controls. Glymphatic transport and solute drainage was quantified using in vivo T1 mapping by magnetic resonance imaging (MRI) after CSF infusion of gadoteric acid. Brain morphometry and aquaporin 4 expression (AQP4) was also assessed. Intracranial pressure (ICP) was measured in separate cohorts. RESULTS: In both of the two models of MCC ciliopathy we found the ventriculomegaly to be associated with normal ICP. We showed that FOXJ1-Cre;CEP164fl/fl mice with hydrocephalus still demonstrated sustained glymphatic transport and normal AQP4 expression along capillaries. In p73-/- mice glymphatic transport was even increased, and this was paralleled by an increase in AQP4 polarization around capillaries. Further, solute drainage via the cribriform plate to the nasal cavity was severely impaired in both ciliopathy models and associated with chronic rhinitis and olfactory bulb hypoplasia. CONCLUSIONS: The combination of sustained glymphatic transport, impaired solute drainage via the cribriform plate to the nasal cavity and hydrocephalus has not previously been reported in models of MCC ciliopathy. Our data enhance our understanding of how different types of ciliopathies contribute to disruption of CNS fluid homeostasis, manifested in pathologies such as hydrocephalus.

CEP164 Deficiency Causes Hyperproliferation of Pancreatic Cancer Cells.

Primary cilia are hair-like projections that protrude from most mammalian cells and mediate various extracellular signaling pathways. Pancreatic ductal adenocarcinoma (PDAC) cells are known to lose their primary cilia, but the relevance of this phenomenon remains unclear. In this study, we generated PDAC-originated Panc1 cells devoid of primary cilia by mutating a centriolar protein, centrosomal protein 164 (CEP164), which is required for ciliogenesis. CEP164 depletion enhanced the clonogenicity of Panc1 cells, along with chemically induced elimination of primary cilia, suggesting that a lack of these organelles promotes PDAC cells proliferation. In addition, the loss of CEP164 altered the cell cycle progression irrespective of absence of primary cilia. We found that CEP164 was co-localized with the GLI2 transcription factor at the mother centriole and controlled its activation, thus inducing Cyclin D-CDK6 expression. Furthermore, CEP164-mutated Panc1 cells were significantly tolerant to KRAS depletion-dependent growth inhibition. This study suggests that CEP164 deficiency is advantageous for PDAC cells proliferation due to not only lack of ciliation but also cilia-independent GLI2-Cyclin D/CDK6 activation, and that CEP164 is a potential therapeutic target for PDAC.

Insights Into the Somatic Mutation Burden of Hepatoblastomas From Brazilian Patients.

Hepatoblastoma is a very rare embryonal liver cancer supposed to arise from the impairment of hepatocyte differentiation during embryogenesis. In this study, we investigated by exome sequencing the burden of somatic mutations in a cohort of 10 hepatoblastomas, including a congenital case. Our data disclosed a low mutational background and pointed out to a novel set of candidate genes for hepatoblastoma biology, which were shown to impact gene expression levels. Only three recurrently mutated genes were detected: CTNNB1 and two novel candidates, CX3CL1 and CEP164. A relevant finding was the identification of a recurrent mutation (A235G) in two hepatoblastomas at the CX3CL1 gene; evaluation of RNA and protein expression revealed upregulation of CX3CL1 in tumors. The analysis was replicated in two independents cohorts, substantiating that an activation of the CX3CL1/CX3CR1 pathway occurs in hepatoblastomas. In inflammatory regions of hepatoblastomas, CX3CL1/CX3CR1 were not detected in the infiltrated lymphocytes, in which they should be expressed in normal conditions, whereas necrotic regions exhibited negative labeling in tumor cells, but strongly positive infiltrated lymphocytes. Altogether, these data suggested that CX3CL1/CX3CR1 upregulation may be a common feature of hepatoblastomas, potentially related to chemotherapy response and progression. In addition, three mutational signatures were identified in hepatoblastomas, two of them with predominance of either the COSMIC signatures 1 and 6, found in all cancer types, or the COSMIC signature 29, mostly related to tobacco chewing habit; a third novel mutational signature presented an unspecific pattern with an increase of C>A mutations. Overall, we present here novel candidate genes for hepatoblastoma, with evidence that CX3CL1/CX3CR1 chemokine signaling pathway is likely involved with progression, besides reporting specific mutational signatures.