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Favero CB, Henshaw RN, Grimsley-Myers CM, Shrestha A, Beier DR, Dwyer ND. Mutation of the BiP/GRP78 gene causes axon outgrowth and fasciculation defects in the thalamocortical connections of the mammalian forebrain. J Comp Neurol 2013; 521:677-96. [PMID: 22821687 PMCID: PMC3515720 DOI: 10.1002/cne.23199] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 05/13/2012] [Accepted: 07/13/2012] [Indexed: 02/05/2023]
Abstract
Proper development of axonal connections is essential for brain function. A forward genetic screen for mice with defects in thalamocortical development previously isolated a mutant called baffled. Here we describe the axonal defects of baffled in further detail and identify a point mutation in the Hspa5 gene, encoding the endoplasmic reticulum chaperone BiP/GRP78. This hypomorphic mutation of BiP disrupts proper development of the thalamocortical axon projection and other forebrain axon tracts, as well as cortical lamination. In baffled mutant brains, a reduced number of thalamic axons innervate the cortex by the time of birth. Thalamocortical and corticothalamic axons are delayed, overfasciculated, and disorganized along their pathway through the ventral telencephalon. Furthermore, dissociated mutant neurons show reduced axon extension in vitro. Together, these findings demonstrate a sensitive requirement for the endoplasmic reticulum chaperone BiP/GRP78 during axon outgrowth and pathfinding in the developing mammalian brain.
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Leshchiner I, Alexa K, Kelsey P, Adzhubei I, Austin-Tse CA, Cooney JD, Anderson H, King MJ, Stottmann RW, Garnaas MK, Ha S, Drummond IA, Paw BH, North TE, Beier DR, Goessling W, Sunyaev SR. Mutation mapping and identification by whole-genome sequencing. Genome Res 2012; 22:1541-8. [PMID: 22555591 PMCID: PMC3409267 DOI: 10.1101/gr.135541.111] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Genetic mapping of mutations in model systems has facilitated the identification of genes contributing to fundamental biological processes including human diseases. However, this approach has historically required the prior characterization of informative markers. Here we report a fast and cost-effective method for genetic mapping using next-generation sequencing that combines single nucleotide polymorphism discovery, mutation localization, and potential identification of causal sequence variants. In contrast to prior approaches, we have developed a hidden Markov model to narrowly define the mutation area by inferring recombination breakpoints of chromosomes in the mutant pool. In addition, we created an interactive online software resource to facilitate automated analysis of sequencing data and demonstrate its utility in the zebrafish and mouse models. Our novel methodology and online tools will make next-generation sequencing an easily applicable resource for mutation mapping in all model systems.
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Stottmann RW, Turbe-Doan A, Tran P, Kratz LE, Moran JL, Kelley RI, Beier DR. Cholesterol metabolism is required for intracellular hedgehog signal transduction in vivo. PLoS Genet 2011; 7:e1002224. [PMID: 21912524 PMCID: PMC3164675 DOI: 10.1371/journal.pgen.1002224] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 06/20/2011] [Indexed: 12/20/2022] Open
Abstract
We describe the rudolph mouse, a mutant with striking defects in both central nervous system and skeletal development. Rudolph is an allele of the cholesterol biosynthetic enzyme, hydroxysteroid (17-beta) dehydrogenase 7, which is an intriguing finding given the recent implication of oxysterols in mediating intracellular Hedgehog (Hh) signaling. We see an abnormal sterol profile and decreased Hh target gene induction in the rudolph mutant, both in vivo and in vitro. Reduced Hh signaling has been proposed to contribute to the phenotypes of congenital diseases of cholesterol metabolism. Recent in vitro and pharmacological data also indicate a requirement for intracellular cholesterol synthesis for proper regulation of Hh activity via Smoothened. The data presented here are the first in vivo genetic evidence supporting both of these hypotheses, revealing a role for embryonic cholesterol metabolism in both CNS development and normal Hh signaling. The molecules and signaling pathways that regulate growth and patterning of the developing embryo are still being elucidated, and one valuable experimental approach is the use of animal models, such as the mouse. We have identified a recessive mutation in the mouse, rudolph, that causes abnormal forebrain development and have determined that the mutated gene encodes hydroxysteroid (17-beta) dehydrogenase 7 gene, an enzyme necessary for cholesterol biosynthesis. Cholesterol is essential for proper signal transduction of the hedgehog family of proteins, key regulators of both developmental biology and tumor progression. We show that hedgehog signaling is diminished in our rudolph mutant. Our conclusions from studying this mouse mutant support two recent hypotheses in developmental biology. First, several human malformation syndromes are known to be caused by defects in cholesterol metabolism, but support linking the malformation to abnormal hedgehog signaling has not definitively been made. Second, while in vitro studies have shown that proper levels of metabolic by-products of cholesterol are necessary for proper hedgehog signaling, our studies offer the strongest genetic animal model evidence to support this idea.
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Zheng Y, Yin H, Boeglin WE, Elias PM, Crumrine D, Beier DR, Brash AR. Lipoxygenases mediate the effect of essential fatty acid in skin barrier formation: a proposed role in releasing omega-hydroxyceramide for construction of the corneocyte lipid envelope. J Biol Chem 2011; 286:24046-56. [PMID: 21558561 DOI: 10.1074/jbc.m111.251496] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A barrier to water loss is vital to maintaining life on dry land. Formation of the mammalian skin barrier requires both the essential fatty acid linoleate and the two lipoxygenases 12R-lipoxygenase (12R-LOX) and epidermal lipoxygenase-3 (eLOX3), although their roles are poorly understood. Linoleate occurs in O-linoleoyl-ω-hydroxyceramide, which, after hydrolysis of the linoleate moiety, is covalently attached to protein via the free ω-hydroxyl of the ceramide, forming the corneocyte lipid envelope, a scaffold between lipid and protein that helps seal the barrier. Here we show using HPLC-UV, LC-MS, GC-MS, and (1)H NMR that O-linoleoyl-ω-hydroxyceramide is oxygenated in a regio- and stereospecific fashion by the consecutive actions of 12R-LOX and eLOX3 and that these products occur naturally in pig and mouse epidermis. 12R-LOX forms 9R-hydroperoxy-linoleoyl-ω-hydroxyceramide, further converted by eLOX3 to specific epoxyalcohol (9R,10R-trans-epoxy-11E-13R-hydroxy) and 9-keto-10E,12Z esters of the ceramide; an epoxy-ketone derivative (9R,10R-trans-epoxy-11E-13-keto) is the most prominent oxidized ceramide in mouse skin. These products are absent in 12R-LOX-deficient mice, which crucially display a near total absence of protein-bound ω-hydroxyceramides and of the corneocyte lipid envelope and die shortly after birth from transepidermal water loss. We conclude that oxygenation of O-linoleoyl-ω-hydroxyceramide is required to facilitate the ester hydrolysis and allow bonding of the ω-hydroxyceramide to protein, providing a coherent explanation for the roles of multiple components in epidermal barrier function. Our study uncovers a hitherto unknown biochemical pathway in which the enzymic oxygenation of ceramides is involved in building a crucial structure of the epidermal barrier.
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Dwyer ND, Manning DK, Moran JL, Mudbhary R, Fleming MS, Favero CB, Vock VM, O'Leary DDM, Walsh CA, Beier DR. A forward genetic screen with a thalamocortical axon reporter mouse yields novel neurodevelopment mutants and a distinct emx2 mutant phenotype. Neural Dev 2011; 6:3. [PMID: 21214893 PMCID: PMC3024922 DOI: 10.1186/1749-8104-6-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Accepted: 01/07/2011] [Indexed: 12/02/2022] Open
Abstract
Background The dorsal thalamus acts as a gateway and modulator for information going to and from the cerebral cortex. This activity requires the formation of reciprocal topographic axon connections between thalamus and cortex. The axons grow along a complex multistep pathway, making sharp turns, crossing expression boundaries, and encountering intermediate targets. However, the cellular and molecular components mediating these steps remain poorly understood. Results To further elucidate the development of the thalamocortical system, we first created a thalamocortical axon reporter line to use as a genetic tool for sensitive analysis of mutant mouse phenotypes. The TCA-tau-lacZ reporter mouse shows specific, robust, and reproducible labeling of thalamocortical axons (TCAs), but not the overlapping corticothalamic axons, during development. Moreover, it readily reveals TCA pathfinding abnormalities in known cortical mutants such as reeler. Next, we performed an unbiased screen for genes involved in thalamocortical development using random mutagenesis with the TCA reporter. Six independent mutant lines show aberrant TCA phenotypes at different steps of the pathway. These include ventral misrouting, overfasciculation, stalling at the corticostriatal boundary, and invasion of ectopic cortical cell clusters. An outcross breeding strategy coupled with a genomic panel of single nucleotide polymorphisms facilitated genetic mapping with small numbers of mutant mice. We mapped a ventral misrouting mutant to the Emx2 gene, and discovered that some TCAs extend to the olfactory bulbs in this mutant. Mapping data suggest that other lines carry mutations in genes not previously known for roles in thalamocortical development. Conclusions These data demonstrate the feasibility of a forward genetic approach to understanding mammalian brain morphogenesis and wiring. A robust axonal reporter enabled sensitive analysis of a specific axon tract inside the mouse brain, identifying mutant phenotypes at multiple steps of the pathway, and revealing a new aspect of the Emx2 mutant. The phenotypes highlight vulnerable choice points and latent tendencies of TCAs, and will lead to a refined understanding of the elements and interactions required to form the thalamocortical system. See Commentary: http://www.biomedcentral.com/1741-7007/9/1
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Bjork BC, Fujiwara Y, Davis SW, Qiu H, Saunders TL, Sandy P, Orkin S, Camper SA, Beier DR. A transient transgenic RNAi strategy for rapid characterization of gene function during embryonic development. PLoS One 2010; 5:e14375. [PMID: 21179568 PMCID: PMC3002952 DOI: 10.1371/journal.pone.0014375] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 11/24/2010] [Indexed: 01/14/2023] Open
Abstract
RNA interference (RNAi) is a powerful strategy for studying the phenotypic consequences of reduced gene expression levels in model systems. To develop a method for the rapid characterization of the developmental consequences of gene dysregulation, we tested the use of RNAi for “transient transgenic” knockdown of mRNA in mouse embryos. These methods included lentiviral infection as well as transposition using the Sleeping Beauty (SB) and PiggyBac (PB) transposable element systems. This approach can be useful for phenotypic validation of putative mutant loci, as we demonstrate by confirming that knockdown of Prdm16 phenocopies the ENU-induced cleft palate (CP) mutant, csp1. This strategy is attractive as an alternative to gene targeting in embryonic stem cells, as it is simple and yields phenotypic information in a matter of weeks. Of the three methodologies tested, the PB transposon system produced high numbers of transgenic embryos with the expected phenotype, demonstrating its utility as a screening method.
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Beier DR. New genetic resources for mammalian developmental biologists. F1000 BIOLOGY REPORTS 2010; 2:72. [PMID: 21173845 PMCID: PMC2989628 DOI: 10.3410/b2-72] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The utilization of homologous recombination in embryonic stem cells as a means to generate mice carrying pre-determined modifications of genomic sequences has revolutionized the study of developmental biology. Recognizing the potential efficiencies that can be obtained by high-throughput production at centralized technology centers, a number of large-scale efforts for generating mice with targeted mutations have been funded. These programs are reaching fruition, and a variety of libraries of embryonic stem cells with defined mutations are now available.
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Stottmann RW, Bjork BC, Doyle JB, Beier DR. Identification of a Van der Woude syndrome mutation in the cleft palate 1 mutant mouse. Genesis 2010; 48:303-8. [PMID: 20196077 DOI: 10.1002/dvg.20618] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Mutations in Interferon Regulatory Factor 6 (IRF6) have been identified in two human allelic syndromes with cleft lip and/or palate: Van der Woude (VWS) and Popliteal Pterygium syndromes (PPS). Furthermore, common IRF6 haplotypes and single nucleotide polymorphisms (SNP) alleles are strongly associated with nonsyndromic clefting defects in multiple ethnic populations. Mutations in the mouse often provide good models for the study of human diseases and developmental processes. We identified the cleft palate 1 (clft1) mouse mutant in a forward genetic screen for phenotypes modeling human congenital disease. In the clft1 mutant, we have identified a novel missense point mutation in the mouse Irf6 gene, which confers an amino acid alteration that has been found in a VWS family. Phenotypic comparison of clft1 mutants to previously reported Irf6 mutant alleles demonstrates the Irf6(clft1) allele is a hypomorphic allele. The cleft palate seen in these mutants appears to be due to abnormal adhesion between the palate and tongue. The Irf6(clft1) allele provides the first mouse model for the study of an etiologic IRF6 missense mutation observed in a human VWS family.
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Kamp A, Peterson MA, Svenson KL, Bjork BC, Hentges KE, Rajapaksha TW, Moran J, Justice MJ, Seidman JG, Seidman CE, Moskowitz IP, Beier DR. Genome-wide identification of mouse congenital heart disease loci. Hum Mol Genet 2010; 19:3105-13. [PMID: 20511334 DOI: 10.1093/hmg/ddq211] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Empirical evidence supporting a genetic basis for the etiology of congenital heart disease (CHD) is limited and few disease-causing mutations have been identified. To identify novel CHD genes, we performed a forward genetic screen to identify mutant mouse lines with heritable CHD. Lines with recessive N-ethyl-N-nitrsourea-induced CHD-causing mutations were identified using a three-generation backcross. A hierarchical screening protocol was used to test the hypothesis that the fetal-to-neonatal circulatory transition unmasks the specific structural heart defects observed in CHD. Mice with heart defects were efficiently ascertained by selecting for pups exhibiting perinatal lethality and characterizing their cardiac pathology. A marked increase of perinatal lethality was observed in the mutagen-treated cohort compared with an untreated backcross population. Cardiac pathology on perinatal lethals revealed cardiovascular defects in 79 pups from 47 of 321 mutagenized lines. All identified structural abnormalities were analogous to previously described forms of human CHD. Furthermore, the phenotypic recurrence and variance patterns across all lines were similar to human CHD prevalence and recurrence patterns. We mapped the locus responsible for heritable atrioventricular septal defects in six lines (avc1-6). Our screen demonstrated that 'sporadic' CHD may have major genetic component and established a practical, efficient approach for identifying CHD candidate genes.
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Shiba D, Manning DK, Koga H, Beier DR, Yokoyama T. Inv acts as a molecular anchor for Nphp3 and Nek8 in the proximal segment of primary cilia. Cytoskeleton (Hoboken) 2010; 67:112-9. [PMID: 20169535 DOI: 10.1002/cm.20428] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A primary cilium is an antenna-like structure extending from the surface of most vertebrate cells. It is structurally divided along its vertical axis into sub-compartments that include the ciliary tip, the shaft, the ciliary necklace segment, the transitional zone and the basal body. We recently discovered that the shaft of the primary cilia has a distinct molecular compartment, termed the "Inv compartment", which is characterized by the accumulation of Inv at the base of primary cilia. Inv was discovered as a causative gene in inv mutant mice. It was later found to be responsible for the infantile type of nephronophthisis (NPHP2). Nephronophthisis (NPHP) is an autosomal recessive kidney disease. Nine causative genes have been identified, with all examined products thought to function in cilia, basal body and/or centrioles. However, their exact intra-ciliary localization and relationship have not been clear. Here, we report that products of Nphp3 and Nek8 (the mouse orthologs of the causative genes for NPHP3 and NPHP9, respectively) localize to the Inv compartment. We also show that Inv is essential for the compartmental localization of Nphp3 and Nek8, whereas localization of Inv does not require Nphp3 or Nek8. Nphp1 and Nphp4 also localize at the proximal region of the cilium, but not in Inv compartment. Our results indicate that Inv acts as an anchor for Nphp3 and Nek8 in the Inv compartment, and suggest that Inv compartment is a candidate site for intra-ciliary interaction of Inv, Nphp3 and Nek8.
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Smits P, Bolton AD, Funari V, Hong M, Boyden ED, Lu L, Manning DK, Dwyer ND, Moran JL, Prysak M, Merriman B, Nelson SF, Bonafé L, Superti-Furga A, Ikegawa S, Krakow D, Cohn DH, Kirchhausen T, Warman ML, Beier DR. Lethal skeletal dysplasia in mice and humans lacking the golgin GMAP-210. N Engl J Med 2010; 362:206-16. [PMID: 20089971 PMCID: PMC3108191 DOI: 10.1056/nejmoa0900158] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Establishing the genetic basis of phenotypes such as skeletal dysplasia in model organisms can provide insights into biologic processes and their role in human disease. METHODS We screened mutagenized mice and observed a neonatal lethal skeletal dysplasia with an autosomal recessive pattern of inheritance. Through genetic mapping and positional cloning, we identified the causative mutation. RESULTS Affected mice had a nonsense mutation in the thyroid hormone receptor interactor 11 gene (Trip11), which encodes the Golgi microtubule-associated protein 210 (GMAP-210); the affected mice lacked this protein. Golgi architecture was disturbed in multiple tissues, including cartilage. Skeletal development was severely impaired, with chondrocytes showing swelling and stress in the endoplasmic reticulum, abnormal cellular differentiation, and increased cell death. Golgi-mediated glycosylation events were altered in fibroblasts and chondrocytes lacking GMAP-210, and these chondrocytes had intracellular accumulation of perlecan, an extracellular matrix protein, but not of type II collagen or aggrecan, two other extracellular matrix proteins. The similarities between the skeletal and cellular phenotypes in these mice and those in patients with achondrogenesis type 1A, a neonatal lethal form of skeletal dysplasia in humans, suggested that achondrogenesis type 1A may be caused by GMAP-210 deficiency. Sequence analysis revealed loss-of-function mutations in the 10 unrelated patients with achondrogenesis type 1A whom we studied. CONCLUSIONS GMAP-210 is required for the efficient glycosylation and cellular transport of multiple proteins. The identification of a mutation affecting GMAP-210 in mice, and then in humans, as the cause of a lethal skeletal dysplasia underscores the value of screening for abnormal phenotypes in model organisms and identifying the causative mutations.
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Bjork BC, Turbe-Doan A, Prysak M, Herron BJ, Beier DR. Prdm16 is required for normal palatogenesis in mice. Hum Mol Genet 2009; 19:774-89. [PMID: 20007998 DOI: 10.1093/hmg/ddp543] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Transcriptional cofactors are essential to the regulation of transforming growth factor beta (TGFbeta) superfamily signaling and play critical and widespread roles during embryonic development, including craniofacial development. We describe the cleft secondary palate 1 (csp1) N-ethyl-N-nitrosourea-induced mouse model of non-syndromic cleft palate (NSCP) that is caused by an intronic Prdm16 splicing mutation. Prdm16 encodes a transcriptional cofactor that regulates TGFbeta signaling, and its expression pattern is consistent with a role in palate and craniofacial development. The cleft palate (CP) appears to be the result of micrognathia and failed palate shelf elevation due to physical obstruction by the tongue, resembling human Pierre Robin sequence (PRS)-like cleft secondary palate. PRDM16 should be considered a candidate for mutation in human clefting disorders, especially NSCP and PRS-like CP.
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Heydemann A, Ceco E, Lim JE, Hadhazy M, Ryder P, Moran JL, Beier DR, Palmer AA, McNally EM. Latent TGF-beta-binding protein 4 modifies muscular dystrophy in mice. J Clin Invest 2009; 119:3703-12. [PMID: 19884661 DOI: 10.1172/jci39845] [Citation(s) in RCA: 141] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Accepted: 09/09/2009] [Indexed: 11/17/2022] Open
Abstract
Most single-gene diseases, including muscular dystrophy, display a nonuniform phenotype. Phenotypic variability arises, in part, due to the presence of genetic modifiers that enhance or suppress the disease process. We employed an unbiased mapping approach to search for genes that modify muscular dystrophy in mice. In a genome-wide scan, we identified a single strong locus on chromosome 7 that influenced two pathological features of muscular dystrophy, muscle membrane permeability and muscle fibrosis. Within this genomic interval, an insertion/deletion polymorphism of 36 bp in the coding region of the latent TGF-beta-binding protein 4 gene (Ltbp4) was found. Ltbp4 encodes a latent TGF-beta-binding protein that sequesters TGF-beta and regulates its availability for binding to the TGF-beta receptor. Insertion of 12 amino acids into the proline-rich region of LTBP4 reduced proteolytic cleavage and was associated with reduced TGF-beta signaling, decreased fibrosis, and improved muscle pathology in a mouse model of muscular dystrophy. In contrast, a 12-amino-acid deletion in LTBP4 was associated with increased proteolysis, SMAD signaling, and fibrosis. These data identify Ltbp4 as a target gene to regulate TGF-beta signaling and modify outcomes in muscular dystrophy.
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Stottmann RW, Tran PV, Turbe-Doan A, Beier DR. Ttc21b is required to restrict sonic hedgehog activity in the developing mouse forebrain. Dev Biol 2009; 335:166-78. [PMID: 19732765 DOI: 10.1016/j.ydbio.2009.08.023] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2009] [Revised: 08/24/2009] [Accepted: 08/24/2009] [Indexed: 10/20/2022]
Abstract
Organizing centers in the developing brain provide an assortment of instructive patterning cues, including Sonic hedgehog (Shh). Here we characterize the forebrain phenotype caused by loss of Ttc21b, a gene we identified in an ENU mutagenesis screen as a novel ciliary gene required for retrograde intraflagellar transport. The Ttc21b mutant has defects in limb, eye and, most dramatically, brain development. We show that Shh signaling is elevated in the rostral portion of the mutant embryo, including in a domain in or near the zona limitans intrathalamica. We demonstrate here that ciliary defects seen in the Ttc21b mutant extend to the embryonic brain, adding forebrain development to the spectrum of tissues affected by defects in ciliary physiology. We show that development of the Ttc21b brain phenotype is modified by lowering levels of the Shh ligand, supporting our hypothesis that the abnormal patterning is a consequence of elevated Shh signaling. Finally, we evaluate Wnt signaling but do not find evidence that this plays a role in causing the perturbed neurodevelopmental phenotype we describe.
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Trapp ML, Galtseva A, Manning DK, Beier DR, Rosenblum ND, Quarmby LM. Defects in ciliary localization of Nek8 is associated with cystogenesis. Pediatr Nephrol 2008; 23:377-87. [PMID: 18189147 PMCID: PMC6890203 DOI: 10.1007/s00467-007-0692-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2007] [Revised: 10/08/2007] [Accepted: 10/10/2007] [Indexed: 01/01/2023]
Abstract
Mutations in the human NIMA (Never in Mitosis gene A)-related kinase 8 (Nek8) are associated with a rare form of the juvenile renal cystic disease, nephronophthisis type 9, and mutations in murine Nek8 cause renal cysts in jck mice. Cystogenesis involves dysfunctional ciliary signaling, and we have previously reported that Nek8 localizes to the primary cilium in mouse kidney epithelial cells. We now report that in developing mouse kidney, Nek8 is detected in the cilia of a subset of ureteric-bud-derived tubules at embryonic day (E)15.5. An increasing proportion of ureteric-bud-derived tubules express ciliary Nek8 until E18.5. Postnatal day 1 and 7 Nek8 is observed with equal frequency in both ureteric-bud and non-ureteric-bud-derived tubules. To investigate the cell biological consequences of kinase-deficient and jck mutant forms of Nek8, we transiently expressed green fluorescent protein (GFP)-tagged constructs in vitro. Mutations in the kinase and C-terminal domains of Nek8 adversely affected ciliary targeting but did not affect ciliogenesis or ciliary length. Consistent with these in vitro observations, kidneys from homozygous jck mice revealed reduced ciliary expression of Nek8 compared with kidneys from heterozygous (unaffected) mice. These data indicate that the ciliary localization of Nek8 in a subset of ureteric-bud-derived kidney tubules is essential for maintaining the integrity of those tubules in the mammalian kidney.
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Sohara E, Luo Y, Zhang J, Manning DK, Beier DR, Zhou J. Nek8 regulates the expression and localization of polycystin-1 and polycystin-2. J Am Soc Nephrol 2008; 19:469-76. [PMID: 18235101 DOI: 10.1681/asn.2006090985] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Nek8 is a serine/threonine kinase that is mutated in the jck (juvenile cystic kidneys) mouse, a model of autosomal recessive juvenile polycystic kidney disease, but its function is poorly understood. We used the jck mouse to study the functional relationship between Nek8 and other proteins that have been implicated in polycystic kidney diseases. In the collecting tubules and collecting ducts of wild-type mice, we found that Nek8 was localized to the proximal portion of primary cilia and was weakly detected in the cytosol. In the jck mutant, however, Nek8 was found along the entire length of cilia. Coimmunoprecipitation experiments demonstrated that Nek8 interacted with polycystin-2, but not with polycystin-1, and that the jck mutation did not affect this interaction. Western blot analysis and real-time reverse transcriptase PCR revealed that the protein and mRNA expression of polycystin-1 (PC1) and polycystin-2 (PC2) were increased in jck mouse kidneys. The jck mutation also led to abnormal phosphorylatin of PC2, and this was associated with longer cilia and ciliary accumulation of PC1 and PC2. Our data suggests that Nek8 interacts with the signal transduction pathways of the polycystins and may control the targeting of these ciliary proteins. Dysfunction Nek8 may lead to cystogenesis by altering the structure and function of cilia in the distal nephron.
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Kubo E, Fatma N, Akagi Y, Beier DR, Singh SP, Singh DP. TAT-mediated PRDX6 protein transduction protects against eye lens epithelial cell death and delays lens opacity. Am J Physiol Cell Physiol 2008; 294:C842-55. [PMID: 18184874 DOI: 10.1152/ajpcell.00540.2007] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A diminished level of endogenous antioxidant in cells/tissues is associated with reduced resistance to oxidative stress. Peroxiredoxin 6 (PRDX6), a protective molecule, regulates gene expression/function by controlling reactive oxygen species (ROS) levels. Using PRDX6 protein linked to TAT, the transduction domain from human immunodeficiency virus type 1 TAT protein, we demonstrated that PRDX6 was transduced into lens epithelial cells derived from rat or mouse lenses. The protein was biologically active, negatively regulating apoptosis and delaying progression of cataractogenesis by attenuating deleterious signaling. Lens epithelial cells from cataractous lenses bore elevated levels of ROS and were susceptible to oxidative stress. These cells harbored increased levels of active transforming growth factor (TGF)-beta 1 and of alpha-smooth muscle actin and beta ig-h3, markers for cataractogenesis. Importantly, cataractous lenses showed a 10-fold reduction in PRDX6 expression, whereas TGF-beta1 mRNA and protein levels were elevated. The changes were reversed, and cataractogenesis was delayed when PRDX6 was supplied. Results suggest that delivery of PRDX6 can postpone cataractogenesis, and this should be an effective approach to delaying cataracts and other degenerative diseases that are associated with increased ROS.
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Leder A, McMenamin J, Zhou F, Moran JL, Beier DR, Leder P. Genome-wide SNP analysis of Tg.AC transgenic mice reveals an oncogenic collaboration between v-Ha-ras and Ink4a, which is absent in p53 deficiency. Oncogene 2007; 27:2456-65. [DOI: 10.1038/sj.onc.1210866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Matera I, Cockroft JL, Moran JL, Beier DR, Goldowitz D, Pavan WJ. A mouse model of Waardenburg syndrome type IV resulting from an ENU-induced mutation in endothelin 3. ACTA ACUST UNITED AC 2007; 20:210-5. [PMID: 17516928 DOI: 10.1111/j.1600-0749.2007.00371.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A line of mutant mice (114-CH19) exhibiting white spotting and preweaning lethality was identified during an N-ethyl-N-nitrosourea (ENU) mutagenesis screen. The trait segregated as a semidominant bellyspot with reduced penetrance. Homozygous mutant mice showed preweaning lethality, and exhibited white spotting over the majority of the body surface, with pigmented patches remaining around the pinnae, eyes and tail. Linkage analysis localized 114-CH19 on mouse chromosome 2, suggesting endothelin 3 (Edn3) as a candidate gene. Sequence analysis of Edn3 identified a G > A transversion that encodes an arginine to histidine substitution (R96H). This mutation is predicted to disrupt furin-mediated proteolytic cleavage of pro-endothelin that is necessary to form biologically active EDN3. This mutation is novel among human and mouse EDN3 mutants, is the first reported EDN3 ENU mutant, and is the second reported EDN3 point mutation. This study demonstrates the power of using ENU mutagenesis screens to generate new animal models of human disease, and expands the spectrum of EDN3 mutant alleles.
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Poirier C, Moran JL, Kovanci E, Petit DC, Beier DR, Bishop CE. Three loci on mouse chromosome 5 and 10 modulate sex determination in XX Ods/+ mice. Genesis 2007; 45:452-5. [PMID: 17607692 DOI: 10.1002/dvg.20312] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In mouse, XY embryos are committed to the male sex determination pathway after the transient expression of the Y-linked Sry gene in the Sertoli cell lineage between 10.5 and 12.5 dpc. In the C57BL/6J strain, male sex determination program can be modulated by some autosomal genes. The C57BL/6J alleles at these autosomal loci can antagonize male sex determination in combination with specific Sry alleles. In this report, the authors have identified an effect of these C57BL/6J specific alleles in combination with a mutated Sox9 allele, Sox9(Ods). Authors report the mapping of three of these genetic loci on mouse chromosome 5 and 10 in a backcross of the Ods mutation to the C57BL/6J background. Our study confirms the importance of the strain C57BL/6J for the investigation of the genetic mechanisms that control sex determination.
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Moran JL, Qiu H, Turbe-Doan A, Yun Y, Boeglin WE, Brash AR, Beier DR. A mouse mutation in the 12R-lipoxygenase, Alox12b, disrupts formation of the epidermal permeability barrier. J Invest Dermatol 2007; 127:1893-7. [PMID: 17429434 DOI: 10.1038/sj.jid.5700825] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Nonbullous congenital ichthyosiform erythroderma (NCIE) is a nonsyndromic form of autosomal recessive congenital ichthyosis characterized by hyperkeratosis and a disruption in the epidermal permeability barrier. Identification of mutations in two lipoxygenases (LOXs), ALOX12B (12R-LOX) and ALOXE3 (eLOX3), and further functional studies implicate ALOX12B and ALOXE3 in the etiology of NCIE. Here, we report a mutation in Alox12b in the recessive ethylnitrosurea-induced mouse mutant, mummy (Alox12b(mmy-Bei)). mummy mutants have red, scaly skin and die perinatally. Histologically, mummy mutants display defects in the epidermis. We mapped mummy to a 1.9 Mb interval on Chr. 11 containing Alox12b (12R-LOX), Aloxe3 (eLOX3) and Alox15b (8-LOX). Sequencing of all three genes identified a nonsense mutation in the catalytic domain of Alox12b. We demonstrate that mummy mutants have a disrupted epidermal permeability barrier and that the nonsense mutation in mummy abolishes the enzyme activity of 12R-LOX. The mummy mutant provides a mouse model for LOX-mediated NCIE and is the first described mouse mutant affecting epidermal barrier formation identified by forward genetics.
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Ackerman KG, Wang J, Luo L, Fujiwara Y, Orkin SH, Beier DR. Gata4 is necessary for normal pulmonary lobar development. Am J Respir Cell Mol Biol 2006; 36:391-7. [PMID: 17142311 PMCID: PMC1899327 DOI: 10.1165/rcmb.2006-0211rc] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Mutations of Fog2 in mice result in a phenotype that includes pulmonary lobar defects. To determine whether formation of the accessory lobe bronchus is mediated by a Gata family cofactor, we evaluated embryonic lungs from mice carrying missense mutations that cause loss of FOG-GATA protein interaction. Lungs from embryos carrying a missense mutation in Gata6 were structurally normal, while lungs from embryos carrying mutations of either Gata4 or of both Gata4 and Gata6 had a structural phenotype that matched the Fog2 mutant phenotype. Expression analysis showed that Gata4 and Fog2 are expressed in the ventral and medial pulmonary mesenchyme during secondary budding. Although Gata4 has not previously been suspected as playing a role in lung development, we have found that a Fog2-Gata4 interaction is critical for the development of normal pulmonary lobar structure, and this phenotype is not influenced by the additional loss of Gata6 interaction. Fog2 and Gata4 in the early pulmonary mesenchyme participate in patterning the secondary bronchus of the accessory lobe.
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Holland KD, Fleming MT, Cheek S, Moran JL, Beier DR, Meisler MH. De novo exon duplication in a new allele of mouse Glra1 (spasmodic). Genetics 2006; 174:2245-7. [PMID: 17028313 PMCID: PMC1698620 DOI: 10.1534/genetics.106.065532] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The novel neurological mutant Cincinatti arose by genomic duplication of exon 5 in the glycine receptor gene Glra1. The mutant transcript results in premature protein truncation. A direct repeat of the pentamer GGGGC is present adjacent to the breakpoints and may have mediated the duplication event by a replication slippage mechanism.
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Lehoczky JA, Cai WW, Douglas JA, Moran JL, Beier DR, Innis JW. Description and genetic mapping of Polypodia: an X-linked dominant mouse mutant with ectopic caudal limbs and other malformations. Mamm Genome 2006; 17:903-13. [PMID: 16964440 DOI: 10.1007/s00335-006-0041-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Accepted: 05/04/2006] [Indexed: 11/25/2022]
Abstract
In this report we present a spontaneous mouse mutant, named Polypodia (Ppd), that primarily exhibits ectopic, ventral/caudal limbs and associated pelvic girdle malformation or duplication. Less penetrant features include diphallia, microphthalmia, small kidney, curled or kinked tail, forelimb anomaly, and skin papillae. Ppd mice have a normal karyotype and no large-scale genomic deletions or insertions by BAC-based array comparative genomic hybridization (CGH). Ppd is X-linked dominant with approximately 20% penetrance on the C3H background and maps to X:61.6 Mb-X:71.24 Mb. The limb and a subset of the nonlimb anomalies are similar to those in offspring from retinoic acid-treated dams at E4.5-5.5 and feature overlap with the Disorganization mouse mutant and human patients with ectopic legs. We hypothesize that Ppd affects very early steps in the formation of caudal structures including limb and appendage number. The existence of noncaudal anomalies implies the involvement of Ppd in a broad array of cell fate decisions.
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Smith LA, Bukanov NO, Husson H, Russo RJ, Barry TC, Taylor AL, Beier DR, Ibraghimov-Beskrovnaya O. Development of polycystic kidney disease in juvenile cystic kidney mice: insights into pathogenesis, ciliary abnormalities, and common features with human disease. J Am Soc Nephrol 2006; 17:2821-31. [PMID: 16928806 DOI: 10.1681/asn.2006020136] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Significant progress in understanding the molecular mechanisms of polycystic kidney disease (PKD) has been made in recent years. Translating this understanding into effective therapeutics will require testing in animal models that closely resemble human PKD by multiple parameters. Similar to autosomal dominant PKD, juvenile cystic kidney (jck) mice develop cysts in multiple nephron segments, including cortical collecting ducts, distal tubules, and loop of Henle. The jck mice display gender dimorphism in kidney disease progression with more aggressive disease in male mice. Gonadectomy experiments show that testosterone aggravates the severity of the disease in jck male mice, while female gonadal hormones have protective effects. EGF receptor is overexpressed and mislocalized in jck cystic epithelia, a hallmark of human disease. Increased cAMP levels in jck kidneys and activation of the B-Raf/extracellular signal-regulated kinase pathway are demonstrated. The effect of jck mutation on the expression of Nek8, a NIMA-related (never in mitosis A) kinase, and polycystins in jck cilia is shown for the first time. Nek8 overexpression and loss of ciliary localization in jck epithelia are accompanied by enhanced expression of polycystins along the cilia. The primary cilia in jck kidneys are significantly more lengthened than the cilia in wild-type mice, suggesting a role for Nek8 in controlling ciliary length. Collectively, these data demonstrate that the jck mice should be useful for testing potential therapies and for studying the molecular mechanisms that link ciliary structure/function and cystogenesis.
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