Judit Horvath

Publications (11)85.04 Total impact

• Article: DNAI2 mutations cause primary ciliary dyskinesia with defects in the outer dynein arm.

  Niki Tomas Loges, Heike Olbrich, Lale Fenske, Huda Mussaffi, Judit Horvath, Manfred Fliegauf, Heiner Kuhl, Gyorgy Baktai, Erzsebet Peterffy, Rahul Chodhari, [......], Christopher O'Callaghan, Hannah Blau, Laszlo Tiszlavicz, Katarzyna Voelkel, Michal Witt, Ewa Zietkiewicz, Juergen Neesen, Richard Reinhardt, Hannah M Mitchison, Heymut Omran
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  ABSTRACT: Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder characterized by chronic destructive airway disease and randomization of left/right body asymmetry. Males often have reduced fertility due to impaired sperm tail function. The complex PCD phenotype results from dysfunction of cilia of the airways and the embryonic node and the structurally related motile sperm flagella. This is associated with underlying ultrastructural defects that frequently involve the outer dynein arm (ODA) complexes that generate cilia and flagella movement. Applying a positional and functional candidate-gene approach, we identified homozygous loss-of-function DNAI2 mutations (IVS11+1G > A) in four individuals from a family with PCD and ODA defects. Further mutational screening of 105 unrelated PCD families detected two distinct homozygous mutations, including a nonsense (c.787C > T) and a splicing mutation (IVS3-3T > G) resulting in out-of-frame transcripts. Analysis of protein expression of the ODA intermediate chain DNAI2 showed sublocalization throughout respiratory cilia. Electron microscopy showed that mutant respiratory cells from these patients lacked DNAI2 protein expression and exhibited ODA defects. High-resolution immunofluorescence imaging demonstrated absence of the ODA heavy chains DNAH5 and DNAH9 from all DNAI2 mutant ciliary axonemes. In addition, we demonstrated complete or distal absence of DNAI2 from ciliary axonemes in respiratory cells of patients with mutations in genes encoding the ODA chains DNAH5 and DNAI1, respectively. Thus, DNAI2 and DNAH5 mutations affect assembly of proximal and distal ODA complexes, whereas DNAI1 mutations mainly disrupt assembly of proximal ODA complexes.
  The American Journal of Human Genetics 10/2008; 83(5):547-58. · 10.60 Impact Factor
• Source

  Available from: Maimoona Zariwala

  Article: Mutations of DNAI1 in primary ciliary dyskinesia: evidence of founder effect in a common mutation.

  Maimoona A Zariwala, Margaret W Leigh, Franck Ceppa, Marcus P Kennedy, Peadar G Noone, Johnny L Carson, Milan J Hazucha, Adriana Lori, Judit Horvath, Heike Olbrich, [......], Hannah M Mitchison, Rahul Chodhari, Eddie M K Chung, Lucy C Morgan, Robbert U de Iongh, Jonathan Rutland, Ugo Pradal, Heymut Omran, Serge Amselem, Michael R Knowles
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  ABSTRACT: Primary ciliary dyskinesia (PCD) is a rare, usually autosomal recessive, genetic disorder characterized by ciliary dysfunction, sino-pulmonary disease, and situs inversus. Disease-causing mutations have been reported in DNAI1 and DNAH5 encoding outer dynein arm (ODA) proteins of cilia. We analyzed DNAI1 to identify disease-causing mutations in PCD and to determine if the previously reported IVS1+2_3insT (219+3insT) mutation represents a "founder" or "hot spot" mutation. Patients with PCD from 179 unrelated families were studied. Exclusion mapping showed no linkage to DNAI1 for 13 families; the entire coding region was sequenced in a patient from the remaining 166 families. Reverse transcriptase-polymerase chain reaction (RT-PCR) was performed on nasal epithelial RNA in 14 families. Mutations in DNAI1 including 12 novel mutations were identified in 16 of 179 (9%) families; 14 harbored biallelic mutations. Deep intronic splice mutations were not identified by reverse transcriptase-polymerase chain reaction. The prevalence of mutations in families with defined ODA defect was 13%; no mutations were found in patients without a defined ODA defect. The previously reported IVS1+2_3insT mutation accounted for 57% (17/30) of mutant alleles, and marker analysis indicates a common founder for this mutation. Seven mutations occurred in three exons (13, 16, and 17); taken together with previous reports, these three exons are emerging as mutation clusters harboring 29% (12/42) of mutant alleles. A total of 10% of patients with PCD are estimated to harbor mutations in DNAI1; most occur as a common founder IVS1+2_3insT or in exons 13, 16, and 17. This information is useful for establishing a clinical molecular genetic test for PCD.
  American Journal of Respiratory and Critical Care Medicine 11/2006; 174(8):858-66. · 11.08 Impact Factor
• Article: Nephrocystin specifically localizes to the transition zone of renal and respiratory cilia and photoreceptor connecting cilia.

  Manfred Fliegauf, Judit Horvath, Christian von Schnakenburg, Heike Olbrich, Dominik Müller, Julia Thumfart, Bernhard Schermer, Gregory J Pazour, Hartmut P H Neumann, Hanswalter Zentgraf, Thomas Benzing, Heymut Omran
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  ABSTRACT: Nephronophthisis (NPHP) is a hereditary cystic kidney disorder that causes renal failure in children and young adults and can be associated with various extrarenal disorders, including retinitis pigmentosa. Six NPHP genes, whose functions are disrupted by autosomal recessive mutations in patients with NPHP, have been identified. The majority of patients with NPHP carry homozygous deletions of NPHP1 encoding nephrocystin. Previous data indicate that nephrocystin forms a complex at cell junctions and focal adhesions. Here, it is shown that nephrocystin specifically localizes at the ciliary base to the transition zone of renal and respiratory cilia and to photoreceptor connecting cilia. During in vitro ciliogenesis of primary human respiratory epithelial cells, nephrocystin can be detected first with a diffuse cytoplasmic localization as soon as cell polarization starts, and translocates to the transition zone when cilia are formed. In columnar respiratory cells, nephrocystin is attached tightly to the axonemal structure of the transition zone at a region that contains the calcium-sensitive cilia autotomy site. In patients with homozygous NPHP1 deletions, nephrocystin is absent from the entire respiratory cell, including the transition zone, which might be of interest for future diagnostic approaches. Cilia formation is not altered in primary nephrocystin-deficient respiratory cells, which is consistent with previous findings obtained for the Caenorhabditis elegans ortholog. In addition, it is shown that the localization pattern of intraflagellar transport proteins and nephrocystin differs, suggesting distinct functional roles. In conclusion, nephrocystin deficiency or dysfunction at the transition zone of renal monocilia and the photoreceptor connecting cilium might explain renal failure and retinal degeneration that are observed in patients with NPHP1.
  Journal of the American Society of Nephrology 10/2006; 17(9):2424-33. · 9.66 Impact Factor
• Source

  Available from: Ralf Sudbrak

  Article: DNAH5 mutations are a common cause of primary ciliary dyskinesia with outer dynein arm defects.

  Nada Hornef, Heike Olbrich, Judit Horvath, Maimoona A Zariwala, Manfred Fliegauf, Niki Tomas Loges, Johannes Wildhaber, Peadar G Noone, Marcus Kennedy, Stylianos E Antonarakis, Jean-Louis Blouin, Lucia Bartoloni, Thomas Nüsslein, Peter Ahrens, Matthias Griese, Heiner Kuhl, Ralf Sudbrak, Michael R Knowles, Richard Reinhardt, Heymut Omran
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  ABSTRACT: Primary ciliary dyskinesia (PCD) is characterized by recurrent airway infections and randomization of left-right body asymmetry. To date, autosomal recessive mutations have only been identified in a small number of patients involving DNAI1 and DNAH5, which encode outer dynein arm components. We screened 109 white PCD families originating from Europe and North America for presence of DNAH5 mutations by haplotype analyses and/or sequencing. Haplotype analyses excluded linkage in 26 families. In 30 PCD families, we identified 33 novel (12 nonsense, 8 frameshift, 5 splicing, and 8 missense mutations) and two known DNAH5 mutations. We observed clustering of mutations within five exons harboring 27 mutant alleles (52%) of the 52 detected mutant alleles. Interestingly, 6 (32%) of 19 PCD families with DNAH5 mutations from North America carry the novel founder mutation 10815delT. Electron microscopic analyses in 22 patients with PCD with mutations invariably detected outer dynein arm ciliary defects. High-resolution immunofluorescence imaging of respiratory epithelial cells from eight patients with DNAH5 mutations showed mislocalization of mutant DNAH5 and accumulation at the microtubule organizing centers. Mutant DNAH5 was absent throughout the ciliary axoneme in seven patients and remained detectable in the proximal ciliary axoneme in one patient carrying compound heterozygous splicing mutations at the 3'-end (IVS75-2A>T, IVS76+5G>A). In a preselected subpopulation with documented outer dynein arm defects (n = 47), DNAH5 mutations were identified in 53% of patients. DNAH5 is frequently mutated in patients with PCD exhibiting outer dynein arm defects and mutations cluster in five exons.
  American Journal of Respiratory and Critical Care Medicine 07/2006; 174(2):120-6. · 11.08 Impact Factor
• Article: Mutations in ACY1, the gene encoding aminoacylase 1, cause a novel inborn error of metabolism.

  Jorn Oliver Sass, Verena Mohr, Heike Olbrich, Udo Engelke, Judit Horvath, Manfred Fliegauf, Niki Tomas Loges, Susanne Schweitzer-Krantz, Ralf Moebus, Polly Weiler, Andreas Kispert, Andrea Superti-Furga, Ron A Wevers, Heymut Omran
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  ABSTRACT: N-terminal acetylation of proteins is a widespread and highly conserved process. Aminoacylase 1 (ACY1; EC 3.5.14) is the most abundant of the aminoacylases, a class of enzymes involved in hydrolysis of N-acetylated proteins. Here, we present four children with genetic deficiency of ACY1. They were identified through organic acid analyses using gas chromatography-mass spectrometry, revealing increased urinary excretion of several N-acetylated amino acids, including the derivatives of methionine, glutamic acid, alanine, leucine, glycine, valine, and isoleucine. Nuclear magnetic resonance spectroscopy analysis of urine samples detected a distinct pattern of N-acetylated metabolites, consistent with ACY1 dysfunction. Functional analyses of patients' lymphoblasts demonstrated ACY1 deficiency. Mutation analysis uncovered recessive loss-of-function or missense ACY1 mutations in all four individuals affected. We conclude that ACY1 mutations in these children led to functional ACY1 deficiency and excretion of N-acetylated amino acids. Questions remain, however, as to the clinical significance of ACY1 deficiency. The ACY1-deficient individuals were ascertained through urine metabolic screening because of unspecific psychomotor delay (one subject), psychomotor delay with atrophy of the vermis and syringomyelia (one subject), marked muscular hypotonia (one subject), and follow-up for early treated biotinidase deficiency and normal clinical findings (one subject). Because ACY1 is evolutionarily conserved in fish, frog, mouse, and human and is expressed in the central nervous system (CNS) in human, a role in CNS function or development is conceivable but has yet to be demonstrated. Thus, at this point, we cannot state whether ACY1 deficiency has pathogenic significance with pleiotropic clinical expression or is simply a biochemical variant. Awareness of this new genetic entity may help both in delineating its clinical significance and in avoiding erroneous diagnoses.
  The American Journal of Human Genetics 04/2006; 78(3):401-9. · 10.60 Impact Factor
• Article: Phosphorylation by casein kinase 2 induces PACS-1 binding of nephrocystin and targeting to cilia.

  Bernhard Schermer, Katja Höpker, Heymut Omran, Cristina Ghenoiu, Manfred Fliegauf, Andrea Fekete, Judit Horvath, Michael Köttgen, Matthias Hackl, Stefan Zschiedrich, Tobias B Huber, Albrecht Kramer-Zucker, Hanswalter Zentgraf, Andree Blaukat, Gerd Walz, Thomas Benzing
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  ABSTRACT: Mutations in proteins localized to cilia and basal bodies have been implicated in a growing number of human diseases. Access of these proteins to the ciliary compartment requires targeting to the base of the cilia. However, the mechanisms involved in transport of cilia proteins to this transitional zone are elusive. Here we show that nephrocystin, a ciliary protein mutated in the most prevalent form of cystic kidney disease in childhood, is expressed in respiratory epithelial cells and accumulates at the base of cilia, overlapping with markers of the basal body area and the transition zone. Nephrocystin interacts with the phosphofurin acidic cluster sorting protein (PACS)-1. Casein kinase 2 (CK2)-mediated phosphorylation of three critical serine residues within a cluster of acidic amino acids in nephrocystin mediates PACS-1 binding, and is essential for colocalization of nephrocystin with PACS-1 at the base of cilia. Inhibition of CK2 activity abrogates this interaction and results in the loss of correct nephrocystin targeting. These data suggest that CK2-dependent transport processes represent a novel pathway of targeting proteins to the cilia.
  The EMBO Journal 01/2006; 24(24):4415-24. · 9.20 Impact Factor
• Article: Phosphorylation by casein kinase 2 induces PACS-1 binding of nephrocystin and targeting to cilia

  Bernhard Schermer, Katja H|[ouml]|pker, Heymut Omran, Cristina Ghenoiu, Manfred Fliegauf, Andrea Fekete, Judit Horvath, Michael K|[ouml]|ttgen, Matthias Hackl, Stefan Zschiedrich, Tobias B Huber, Albrecht Kramer-Zucker, Hanswalter Zentgraf, Andree Blaukat, Gerd Walz, Thomas Benzing
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  ABSTRACT: Mutations in proteins localized to cilia and basal bodies have been implicated in a growing number of human diseases. Access of these proteins to the ciliary compartment requires targeting to the base of the cilia. However, the mechanisms involved in transport of cilia proteins to this transitional zone are elusive. Here we show that nephrocystin, a ciliary protein mutated in the most prevalent form of cystic kidney disease in childhood, is expressed in respiratory epithelial cells and accumulates at the base of cilia, overlapping with markers of the basal body area and the transition zone. Nephrocystin interacts with the phosphofurin acidic cluster sorting protein (PACS)-1. Casein kinase 2 (CK2)-mediated phosphorylation of three critical serine residues within a cluster of acidic amino acids in nephrocystin mediates PACS-1 binding, and is essential for colocalization of nephrocystin with PACS-1 at the base of cilia. Inhibition of CK2 activity abrogates this interaction and results in the loss of correct nephrocystin targeting. These data suggest that CK2-dependent transport processes represent a novel pathway of targeting proteins to the cilia.
  The EMBO Journal 11/2005; 24(24):4415-4424. · 9.20 Impact Factor
• Article: Mislocalization of DNAH5 and DNAH9 in respiratory cells from patients with primary ciliary dyskinesia.

  Manfred Fliegauf, Heike Olbrich, Judit Horvath, Johannes H Wildhaber, Maimoona A Zariwala, Marcus Kennedy, Michael R Knowles, Heymut Omran
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  ABSTRACT: Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder characterized by recurrent infections of the airways and situs inversus in half of the affected offspring. The most frequent genetic defects comprise recessive mutations of DNAH5 and DNAI1, which encode outer dynein arm (ODA) components. Diagnosis of PCD usually relies on electron microscopy, which is technically demanding and sometimes difficult to interpret. Using specific antibodies, we determined the subcellular localization of the ODA heavy chains DNAH5 and DNAH9 in human respiratory epithelial and sperm cells of patients with PCD and control subjects by high-resolution immunofluorescence imaging. We also assessed cilia and sperm tail function by high-speed video microscopy. In normal ciliated airway epithelium, DNAH5 and DNAH9 show a specific regional distribution along the ciliary axoneme, indicating the existence of at least two distinct ODA types. DNAH5 was completely or only distally absent from the respiratory ciliary axoneme in patients with PCD with DNAH5- (n = 3) or DNAI1- (n = 1) mutations, respectively, and instead accumulated at the microtubule-organizing centers. In contrast to respiratory cilia, sperm tails from a patient with DNAH5 mutations had normal ODA heavy chain distribution, suggesting different modes of ODA generation in these cell types. Blinded investigation of a large cohort of patients with PCD and control subjects identified DNAH5 mislocalization in all patients diagnosed with ODA defects by electron microscopy (n = 16). Cilia with complete axonemal DNAH5 deficiency were immotile, whereas cilia with distal DNAH5 deficiency showed residual motility. Immunofluorescence staining can detect ODA defects, which will possibly aid PCD diagnosis.
  American Journal of Respiratory and Critical Care Medicine 07/2005; 171(12):1343-9. · 11.08 Impact Factor
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  Available from: Heymut Omran

  Article: Identification of the human CYS1 gene and candidate gene analysis in Boichis disease.

  Manfred Fliegauf, Christian Fröhlich, Judit Horvath, Heike Olbrich, Friedhelm Hildebrandt, Heymut Omran
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  ABSTRACT: Recessive mutations cause cystic kidney disease and a variable degree of biliary liver fibrosis in cpk mice. Recently, the responsible murine gene ( Cys1) was identified and expression in renal cilia demonstrated. Here we describe the cDNA cloning of the full-length coding region of the orthologous human CYS1 gene. CYS1 is located on Chromosome 2p25. The CYS1 genomic region comprises three coding exons, which span 22 kb. The transcript harbors an open reading frame of 477 nucleotides encoding a protein with 158 amino acid residues, which is called cystin. Northern analysis identified an expression pattern resembling that of murine Cys1. We studied affected individuals of eight families with nephronophthisis and liver fibrosis for evidence of CYS1 mutations. All three coding exons were amplified by polymerase chain reaction and directly sequenced. Despite the failure to detect a mutation, the human cystin gene remains an interesting candidate for recessive cystic kidney disease.
  Pediatric Nephrology 07/2003; 18(6):498-505. · 2.52 Impact Factor
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  Available from: Maimoona Zariwala

  Article: Mis-localization of DNAH5 and DNAH9 in respiratory cells from primary ciliary dyskinesia patients

  Manfred Fliegauf, Heike Olbrich, Judit Horvath, Johannes H Wildhaber, Maimoona A Zariwala, Marcus Kennedy, Michael R Knowles, Heymut Omran
• Source

  Available from: Hannah Blau

  Article: DNAI2 mutations can cause primary ciliary dyskinesia with outer dynein arm defects.

  Niki Tomas Loges, Heike Olbrich, Lale Fenske, Judit Horvath, Manfred Fliegauf, Heiner Kuhl, Gyorgy Baktai, Erzsebet Peterffy, Rahul Chodhari, Eddie M K Chung, [......], Huda Mussaffi-Georgy, Hannah Blau, Laszlo Tiszlavicz, Katarzyna Voelkel, Michal Witt, Ewa Ziętkiewicz, Juergen Neesen, Richard Reinhardt, Hannah M Mitchison, Heymut Omran
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  ABSTRACT: This is the author’s final draft of the paper published as The American Journal of Human Genetics, 2008, 83 (5), pp. 547-558. The final published version is available at http://www.elsevier.com, Doi: 10.1016/j.ajhg.2008.10.001. Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder characterized by recurrent infections of the airways and randomization of left/right body asymmetry. The phenotype results from dysfunction of motile cilia of the respiratory epithelium and the embryonic node. Dysmotile sperm tails often cause infertility in male PCD patients. Underlying ultrastructural defects frequently involve outer dynein arms (ODA), which are responsible for generation of cilia movement. We recently showed that recessive mutations of DNAH5 encoding a heavy dynein chain are frequently found in PCD with ODA defects. Genes (DNAI1, TXNDC3, DNAH11) encoding for other ODA components can also account for PCD. Here, we analyzed the protein expression of the ODA intermediate chain DNAI2 and found sub-localization throughout respiratory cilia and sperm tails. Mutational screening of 105 PCD families revealed in one affected a homozygous mutation within the facultative splice acceptor site of exon 4. RNA studies confirmed absence of exon 4 in all transcripts predicting a premature stop codon. Consistently mutant respiratory cells lacked DNAI2 expression and exhibited ODA defects by electron microscopy. High-resolution immunofluorescence imaging demonstrated mis-localization of DNAH5 indicating that DNAI2 is essential for assembly of these ODA components. In addition we report homozygous loss-of-function DNAI2 mutations located within the obligatory splice donor site of exon 11 in four affected individuals with ODA defects originating from a consanguineous PCD family that showed significant linkage to the DNAI2 locus in a total genome scan. In summary, we provide the first evidence that DNAI2 can account for PCD with ODA defects.