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Karlien L M Coene,
Dorus A Mans,
Karsten Boldt,
C Johannes Gloeckner,
Jeroen van Reeuwijk,
Emine Bolat,
Susanne Roosing,
Stef J F Letteboer,
Theo A Peters,
Frans P M Cremers,
Marius Ueffing,
Ronald Roepman
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ABSTRACT: Recent studies have established ciliary dysfunction as the underlying cause of a broad range of multi-organ phenotypes, known as 'ciliopathies'. Ciliopathy-associated proteins have a common site of action in the cilium, however, their overall importance for ciliary function differs, as implied by the extreme variability in ciliopathy phenotypes. The aim of this study was to gain more insight in the function of two ciliopathy-associated protein homologs, RPGR interacting protein 1 (RPGRIP1) and RPGRIP1-like protein (RPGRIP1L). Mutations in RPGRIP1 lead to the eye-restricted disease Leber congenital amaurosis, while mutations in RPGRIP1L are causative for Joubert and Meckel syndrome, which affect multiple organs and are at the severe end of the ciliopathy spectrum. Using tandem affinity purification in combination with mass spectrometry, we identified Nek4 serine/threonine kinase as a prominent component of both the RPGRIP1- as well as the RPGRIP1L-associated protein complex. In ciliated cells, this kinase localized to basal bodies, while in ciliated organs, the kinase was predominantly detected at the ciliary rootlet. Down-regulation of NEK4 in ciliated cells led to a significant decrease in cilium assembly, pointing to a role for Nek4 in cilium dynamics. We now hypothesize that RPGRIP1 and RPGRIP1L function as cilium-specific scaffolds that recruit a Nek4 signaling network which regulates cilium stability. Our data are in line with previously established roles in the cilium of other members of the Nek protein family and define NEK4 as a ciliopathy candidate gene.
Human Molecular Genetics 06/2011; 20(18):3592-605. · 7.64 Impact Factor
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Audrey Putoux,
Sophie Thomas, Karlien L M Coene,
Erica E Davis,
Yasemin Alanay,
Gönül Ogur,
Elif Uz,
Daniela Buzas,
Céline Gomes,
Sophie Patrier, [......],
Nicolas Goudin,
Stanislas Lyonnet,
Férechté Encha-Razavi,
Jean-Pierre Siffroi,
Mark Winey,
Nicholas Katsanis,
Marie Gonzales,
Michel Vekemans,
Philip L Beales,
Tania Attié-Bitach
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ABSTRACT: KIF7, the human ortholog of Drosophila Costal2, is a key component of the Hedgehog signaling pathway. Here we report mutations in KIF7 in individuals with hydrolethalus and acrocallosal syndromes, two multiple malformation disorders with overlapping features that include polydactyly, brain abnormalities and cleft palate. Consistent with a role of KIF7 in Hedgehog signaling, we show deregulation of most GLI transcription factor targets and impaired GLI3 processing in tissues from individuals with KIF7 mutations. KIF7 is also a likely contributor of alleles across the ciliopathy spectrum, as sequencing of a diverse cohort identified several missense mutations detrimental to protein function. In addition, in vivo genetic interaction studies indicated that knockdown of KIF7 could exacerbate the phenotype induced by knockdown of other ciliopathy transcripts. Our data show the role of KIF7 in human primary cilia, especially in the Hedgehog pathway through the regulation of GLI targets, and expand the clinical spectrum of ciliopathies.
Nature Genetics 06/2011; 43(6):601-6. · 35.53 Impact Factor
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Edgar A Otto,
Toby W Hurd,
Rannar Airik,
Moumita Chaki,
Weibin Zhou,
Corinne Stoetzel,
Suresh B Patil,
Shawn Levy,
Amiya K Ghosh,
Carlos A Murga-Zamalloa, [......],
Gudrun Nürnberg,
Peter Nürnberg,
Eric A Pierce,
Peter K Jackson,
Corinne Antignac,
Sophie Saunier,
Ronald Roepman,
Helene Dollfus,
Hemant Khanna,
Friedhelm Hildebrandt
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ABSTRACT: Nephronophthisis-related ciliopathies (NPHP-RC) are recessive disorders that feature dysplasia or degeneration occurring preferentially in the kidney, retina and cerebellum. Here we combined homozygosity mapping with candidate gene analysis by performing 'ciliopathy candidate exome capture' followed by massively parallel sequencing. We identified 12 different truncating mutations of SDCCAG8 (serologically defined colon cancer antigen 8, also known as CCCAP) in 10 families affected by NPHP-RC. We show that SDCCAG8 is localized at both centrioles and interacts directly with OFD1 (oral-facial-digital syndrome 1), which is associated with NPHP-RC. Depletion of sdccag8 causes kidney cysts and a body axis defect in zebrafish and induces cell polarity defects in three-dimensional renal cell cultures. This work identifies loss of SDCCAG8 function as a cause of a retinal-renal ciliopathy and validates exome capture analysis for broadly heterogeneous single-gene disorders.
Nature Genetics 10/2010; 42(10):840-50. · 35.53 Impact Factor
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Dikla Bandah-Rozenfeld,
Rob W J Collin,
Eyal Banin,
L Ingeborgh van den Born, Karlien L M Coene,
Anna M Siemiatkowska,
Lina Zelinger,
Muhammad I Khan,
Dirk J Lefeber,
Inbar Erdinest, [......],
Francesca Simonelli,
Krysta Voesenek,
Ellen A W Blokland,
Tim M Strom,
Caroline C W Klaver,
Raheel Qamar,
Sandro Banfi,
Frans P M Cremers,
Dror Sharon,
Anneke I den Hollander
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ABSTRACT: Retinitis pigmentosa (RP) is a heterogeneous group of inherited retinal diseases caused by progressive degeneration of the photoreceptor cells. Using autozygosity mapping, we identified two families, each with three affected siblings sharing large overlapping homozygous regions that harbored the IMPG2 gene on chromosome 3. Sequence analysis of IMPG2 in the two index cases revealed homozygous mutations cosegregating with the disease in the respective families: three affected siblings of Iraqi Jewish ancestry displayed a nonsense mutation, and a Dutch family displayed a 1.8 kb genomic deletion that removes exon 9 and results in the absence of seven amino acids in a conserved SEA domain of the IMPG2 protein. Transient transfection of COS-1 cells showed that a construct expressing the wild-type SEA domain is properly targeted to the plasma membrane, whereas the mutant lacking the seven amino acids appears to be retained in the endoplasmic reticulum. Mutation analysis in ten additional index cases that were of Dutch, Israeli, Italian, and Pakistani origin and had homozygous regions encompassing IMPG2 revealed five additional mutations; four nonsense mutations and one missense mutation affecting a highly conserved phenylalanine residue. Most patients with IMPG2 mutations showed an early-onset form of RP with progressive visual-field loss and deterioration of visual acuity. The patient with the missense mutation, however, was diagnosed with maculopathy. The IMPG2 gene encodes the interphotoreceptor matrix proteoglycan IMPG2, which is a constituent of the interphotoreceptor matrix. Our data therefore show that mutations in a structural component of the interphotoreceptor matrix can cause arRP.
The American Journal of Human Genetics 08/2010; 87(2):199-208. · 10.60 Impact Factor
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Karlien L M Coene,
Ronald Roepman,
Dan Doherty,
Bushra Afroze,
Hester Y Kroes,
Stef J F Letteboer,
Lock H Ngu,
Bartlomiej Budny,
Erwin van Wijk,
Nicholas T Gorden,
Malika Azhimi,
Christel Thauvin-Robinet,
Joris A Veltman,
Mireille Boink,
Tjitske Kleefstra,
Frans P M Cremers,
Hans van Bokhoven,
Arjan P M de Brouwer
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ABSTRACT: We ascertained a multi-generation Malaysian family with Joubert syndrome (JS). The presence of asymptomatic obligate carrier females suggested an X-linked recessive inheritance pattern. Affected males presented with mental retardation accompanied by postaxial polydactyly and retinitis pigmentosa. Brain MRIs showed the presence of a "molar tooth sign," which classifies this syndrome as classic JS with retinal involvement. Linkage analysis showed linkage to Xpter-Xp22.2 and a maximum LOD score of 2.06 for marker DXS8022. Mutation analysis revealed a frameshift mutation, p.K948NfsX8, in exon 21 of OFD1. In an isolated male with JS, a second frameshift mutation, p.E923KfsX3, in the same exon was identified. OFD1 has previously been associated with oral-facial-digital type 1 (OFD1) syndrome, a male-lethal X-linked dominant condition, and with X-linked recessive Simpson-Golabi-Behmel syndrome type 2 (SGBS2). In a yeast two-hybrid screen of a retinal cDNA library, we identified OFD1 as an interacting partner of the LCA5-encoded ciliary protein lebercilin. We show that X-linked recessive mutations in OFD1 reduce, but do not eliminate, the interaction with lebercilin, whereas X-linked dominant OFD1 mutations completely abolish binding to lebercilin. In addition, recessive mutations in OFD1 did not affect the pericentriolar localization of the recombinant protein in hTERT-RPE1 cells, whereas this localization was lost for dominant mutations. These findings offer a molecular explanation for the phenotypic spectrum observed for OFD1 mutations; this spectrum now includes OFD1 syndrome, SGBS2, and JS.
The American Journal of Human Genetics 10/2009; 85(4):465-81. · 10.60 Impact Factor
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Nicholas T Gorden,
Heleen H Arts,
Melissa A Parisi, Karlien L M Coene,
Stef J F Letteboer,
Sylvia E C van Beersum,
Dorus A Mans,
Abigail Hikida,
Melissa Eckert,
Dana Knutzen, [......],
John B Vincent,
Friedhelm Hildebrandt,
Edwin W Rubel,
David W Raible,
Nine V A M Knoers,
Phillip F Chance,
Ronald Roepman,
Cecilia B Moens,
Ian A Glass,
Dan Doherty
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ABSTRACT: Joubert syndrome and related disorders (JSRD) are primarily autosomal-recessive conditions characterized by hypotonia, ataxia, abnormal eye movements, and intellectual disability with a distinctive mid-hindbrain malformation. Variable features include retinal dystrophy, cystic kidney disease, and liver fibrosis. JSRD are included in the rapidly expanding group of disorders called ciliopathies, because all six gene products implicated in JSRD (NPHP1, AHI1, CEP290, RPGRIP1L, TMEM67, and ARL13B) function in the primary cilium/basal body organelle. By using homozygosity mapping in consanguineous families, we identify loss-of-function mutations in CC2D2A in JSRD patients with and without retinal, kidney, and liver disease. CC2D2A is expressed in all fetal and adult tissues tested. In ciliated cells, we observe localization of recombinant CC2D2A at the basal body and colocalization with CEP290, whose cognate gene is mutated in multiple hereditary ciliopathies. In addition, the proteins can physically interact in vitro, as shown by yeast two-hybrid and GST pull-down experiments. A nonsense mutation in the zebrafish CC2D2A ortholog (sentinel) results in pronephric cysts, a hallmark of ciliary dysfunction analogous to human cystic kidney disease. Knockdown of cep290 function in sentinel fish results in a synergistic pronephric cyst phenotype, revealing a genetic interaction between CC2D2A and CEP290 and implicating CC2D2A in cilium/basal body function. These observations extend the genetic spectrum of JSRD and provide a model system for studying extragenic modifiers in JSRD and other ciliopathies.
The American Journal of Human Genetics 11/2008; 83(5):559-71. · 10.60 Impact Factor
