RESUMO
Polymerizing laminins are multi-domain basement membrane (BM) glycoproteins that self-assemble into cell-anchored planar lattices to establish the initial BM scaffold. Nidogens, collagen-IV and proteoglycans then bind to the scaffold at different domain loci to create a mature BM. The LN domains of adjacent laminins bind to each other to form a polymer node, while the LG domains attach to cytoskeletal-anchoring integrins and dystroglycan, as well as to sulfatides and heparan sulfates. The polymer node, the repeating unit of the polymer scaffold, is organized into a near-symmetrical triskelion. The structure, recently solved by cryo-electron microscopy in combination with AlphaFold2 modeling and biochemical studies, reveals how the LN surface residues interact with each other and how mutations cause failures of self-assembly in an emerging group of diseases, the LN-lamininopathies, that include LAMA2-related dystrophy and Pierson syndrome.
Assuntos
Membrana Basal , Laminina , Humanos , Laminina/metabolismo , Laminina/química , Laminina/genética , Animais , Membrana Basal/metabolismo , Distrofias Musculares/metabolismo , Distrofias Musculares/genética , Deformidades Congênitas dos Membros/metabolismo , Deformidades Congênitas dos Membros/genética , Mutação , Síndrome Nefrótica , Distúrbios Pupilares , Síndromes Miastênicas CongênitasRESUMO
Human families with chromosomal rearrangements at 2q31, where the human HOXD locus maps, display mesomelic dysplasia, a severe shortening and bending of the limb. In mice, the dominant Ulnaless inversion of the HoxD cluster produces a similar phenotype suggesting the same origin for these malformations in humans and mice. Here we engineer 1 Mb inversion including the HoxD gene cluster, which positioned Hoxd13 close to proximal limb enhancers. Using this model, we show that these enhancers contact and activate Hoxd13 in proximal cells, inducing the formation of mesomelic dysplasia. We show that a secondary Hoxd13 null mutation in-cis with the inversion completely rescues the alterations, demonstrating that ectopic HOXD13 is directly responsible for this bone anomaly. Single-cell expression analysis and evaluation of HOXD13 binding sites suggests that the phenotype arises primarily by acting through genes normally controlled by HOXD13 in distal limb cells. Altogether, these results provide a conceptual and mechanistic framework to understand and unify the molecular origins of human mesomelic dysplasia associated with 2q31.
Assuntos
Anormalidades Múltiplas/genética , Doenças do Desenvolvimento Ósseo/genética , Proteínas de Homeodomínio/genética , Deformidades Congênitas dos Membros/genética , Fatores de Transcrição/genética , Anormalidades Múltiplas/embriologia , Anormalidades Múltiplas/metabolismo , Animais , Doenças do Desenvolvimento Ósseo/embriologia , Doenças do Desenvolvimento Ósseo/metabolismo , Modelos Animais de Doenças , Feminino , Deleção de Genes , Proteínas de Homeodomínio/metabolismo , Humanos , Deformidades Congênitas dos Membros/embriologia , Deformidades Congênitas dos Membros/metabolismo , Mutação com Perda de Função , Masculino , Camundongos Endogâmicos C57BL , Família Multigênica , Fatores de Transcrição/metabolismoRESUMO
The extensive clinical and genetic heterogeneity of congenital limb malformation calls for comprehensive genome-wide analysis of genetic variation. Genome sequencing (GS) has the potential to identify all genetic variants. Here we aim to determine the diagnostic potential of GS as a comprehensive one-test-for-all strategy in a cohort of undiagnosed patients with congenital limb malformations. We collected 69 cases (64 trios, 1 duo, 5 singletons) with congenital limb malformations with no molecular diagnosis after standard clinical genetic testing and performed genome sequencing. We also developed a framework to identify potential noncoding pathogenic variants. We identified likely pathogenic/disease-associated variants in 12 cases (17.4%) including four in known disease genes, and one repeat expansion in HOXD13. In three unrelated cases with ectrodactyly, we identified likely pathogenic variants in UBA2, establishing it as a novel disease gene. In addition, we found two complex structural variants (3%). We also identified likely causative variants in three novel high confidence candidate genes. We were not able to identify any noncoding variants. GS is a powerful strategy to identify all types of genomic variants associated with congenital limb malformation, including repeat expansions and complex structural variants missed by standard diagnostic approaches. In this cohort, no causative noncoding SNVs could be identified.
Assuntos
Heterogeneidade Genética , Proteínas de Homeodomínio/genética , Deformidades Congênitas dos Membros/genética , Mutação , Fatores de Transcrição/genética , Enzimas Ativadoras de Ubiquitina/genética , Sequência de Bases , Estudos de Coortes , Variações do Número de Cópias de DNA , Expressão Gênica , Testes Genéticos , Humanos , Lactente , Deformidades Congênitas dos Membros/metabolismo , Deformidades Congênitas dos Membros/patologia , Masculino , Linhagem , Fatores de Transcrição/deficiência , Enzimas Ativadoras de Ubiquitina/deficiência , Sequenciamento Completo do GenomaRESUMO
MicroRNAs (miRNAs, miRs) finely tune protein expression and target networks of hundreds to thousands of genes that control specific biological processes. They are critical regulators of glycosylation, one of the most diverse and abundant post-translational modifications. In recent work, miRs have been shown to predict the biological functions of glycosylation enzymes, leading to the "miRNA proxy hypothesis" which states, "if a miR drives a specific biological phenotype..., the targets of that miR will drive the same biological phenotype." Testing of this powerful hypothesis is hampered by our lack of knowledge about miR targets. Target prediction suffers from low accuracy and a high false prediction rate. Herein, we develop a high-throughput experimental platform to analyze miR-target interactions, miRFluR. We utilize this system to analyze the interactions of the entire human miRome with beta-3-glucosyltransferase (B3GLCT), a glycosylation enzyme whose loss underpins the congenital disorder Peters' Plus Syndrome. Although this enzyme is predicted by multiple algorithms to be highly targeted by miRs, we identify only 27 miRs that downregulate B3GLCT, a >96% false positive rate for prediction. Functional enrichment analysis of these validated miRs predicts phenotypes associated with Peters' Plus Syndrome, although B3GLCT is not in their known target network. Thus, biological phenotypes driven by B3GLCT may be driven by the target networks of miRs that regulate this enzyme, providing additional evidence for the miRNA proxy hypothesis.
Assuntos
Fenda Labial/metabolismo , Córnea/anormalidades , Galactosiltransferases/metabolismo , Glucosiltransferases/metabolismo , Transtornos do Crescimento/metabolismo , Ensaios de Triagem em Larga Escala/métodos , Deformidades Congênitas dos Membros/metabolismo , MicroRNAs/metabolismo , Regiões 3' não Traduzidas , Algoritmos , Fenda Labial/genética , Córnea/metabolismo , Regulação para Baixo/fisiologia , Galactosiltransferases/genética , Glucosiltransferases/genética , Transtornos do Crescimento/genética , Células HEK293 , Humanos , Deformidades Congênitas dos Membros/genética , Proteínas Luminescentes/genética , Regulação para Cima/fisiologia , Proteína Vermelha FluorescenteRESUMO
We report a case of a 1-year and 2-month-old girl with clinical features consistent with congenital hemidysplasia with ichthyosis and limb defects syndrome. Sterol analysis from skin flakes revealed increased levels of a mono 4-alpha methyl sterol also seen in plasma as well as the presence of 4-alpha-carboxy-4-methyl-cholest-8(9)-en-3beta-ol and several keto-sterols, which are usually below the limit of detection. This sterol pattern is consistent with abnormal function of the 4-alpha-methylsterol-4-demethylase complex. NSDHL gene testing revealed the presence of a variant of uncertain significance, c.130G>A (p.Gly44Ser). This missense mutation currently is not included in population databases (ExAC no frequency) and has not been reported in individuals with an NSDHL-related condition. Parental studies showed that neither parent carries the NSDHL variant. On this basis, this variant has been reclassified as likely pathogenic. Symptomatic treatment with keratolytic agents, emollients and ketoconazole was initiated.
Assuntos
3-Hidroxiesteroide Desidrogenases/genética , Anormalidades Múltiplas/genética , DNA/genética , Doenças Genéticas Ligadas ao Cromossomo X/genética , Eritrodermia Ictiosiforme Congênita/genética , Deformidades Congênitas dos Membros/genética , Mutação de Sentido Incorreto , 3-Hidroxiesteroide Desidrogenases/metabolismo , Anormalidades Múltiplas/diagnóstico , Anormalidades Múltiplas/metabolismo , Análise Mutacional de DNA , Diagnóstico Diferencial , Feminino , Doenças Genéticas Ligadas ao Cromossomo X/diagnóstico , Doenças Genéticas Ligadas ao Cromossomo X/metabolismo , Variação Genética , Humanos , Eritrodermia Ictiosiforme Congênita/diagnóstico , Eritrodermia Ictiosiforme Congênita/metabolismo , Lactente , Deformidades Congênitas dos Membros/diagnóstico , Deformidades Congênitas dos Membros/metabolismo , RadiografiaRESUMO
Aims: Split-hand/split-foot malformation (SHFM) is a developmental and congenital limb malformation characterized by variable degrees of medial clefting or absence of one or more digits in hands and/or feet. The aim of this study was to identify the underlying cause of three consanguineous Pakistani families showing various types of SHFM-related features. Materials and Methods: Standard molecular methods, including whole-genome sequencing (WGS), whole-exome sequencing (WES), microsatellite markers-based genotyping, and Sanger sequencing were performed to search for the likely causative variants. Results: In family A, WES revealed a novel homozygous missense variant [c.338G>A, p.(Gly113Asp)] in the WNT10B gene. In family B, microsatellite-based genotyping followed by Sanger sequencing revealed a novel homozygous 13 base pairs deletion [c.884-896delTCCAGCCCCGTCT, p.(Phe295Cysfs*87)] in the same gene. In family C, WGS divulged a previously reported heterozygous missense variant [c.956G>A, p.(Arg319His)] in the TP63 gene. Conclusions: Mapping and sequencing genes and variants for severe skeletal disorders, such as SHRM, will facilitate establishing specific genotype-phenotype correlations and providing genetic counseling for the families suffering from such conditions.
Assuntos
Deformidades Congênitas dos Membros/genética , Proteínas Proto-Oncogênicas/genética , Fatores de Transcrição/genética , Proteínas Supressoras de Tumor/genética , Proteínas Wnt/genética , Adulto , Criança , Pré-Escolar , Família , Feminino , Estudos de Associação Genética , Genótipo , Heterozigoto , Homozigoto , Humanos , Deformidades Congênitas dos Membros/metabolismo , Masculino , Pessoa de Meia-Idade , Mutação de Sentido Incorreto , Paquistão/epidemiologia , Linhagem , Fenótipo , Proteínas Proto-Oncogênicas/metabolismo , Fatores de Transcrição/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Sequenciamento do Exoma , Proteínas Wnt/metabolismo , Adulto JovemAssuntos
Alelos , Substituição de Aminoácidos , Predisposição Genética para Doença , Deformidades Congênitas dos Membros/diagnóstico , Deformidades Congênitas dos Membros/genética , MAP Quinase Quinase Quinases/genética , Mutação de Sentido Incorreto , Animais , Deleção Cromossômica , Cromossomos Humanos Par 7 , Análise Mutacional de DNA , Modelos Animais de Doenças , Evolução Molecular , Estudos de Associação Genética , Humanos , Deformidades Congênitas dos Membros/metabolismo , MAP Quinase Quinase Quinases/química , MAP Quinase Quinase Quinases/metabolismo , Camundongos , Camundongos Knockout , Modelos Moleculares , Polimorfismo de Nucleotídeo Único , Conformação Proteica , Transdução de Sinais , Relação Estrutura-AtividadeRESUMO
Defects in serine biosynthesis resulting from loss of function mutations in PHGDH, PSAT1, and PSPH cause a set of rare, autosomal recessive diseases known as Neu-Laxova syndrome (NLS) or serine-deficiency disorders. The diseases present with a broad range of phenotypes including lethality, severe neurological manifestations, seizures, and intellectual disability. However, because L-serine supplementation, especially if started prenatally, can ameliorate and in some cases even prevent symptoms, knowledge of pathogenic variants is medically actionable. Here, we describe a functional assay that leverages the evolutionary conservation of an enzyme in the serine biosynthesis pathway, phosphoserine aminotransferase, and the ability of the human protein-coding sequence (PSAT1) to functionally replace its yeast ortholog (SER1). Results from our quantitative, yeast-based assay agree well with clinical annotations and expectations based on the disease literature. Using this assay, we have measured the functional impact of the 199 PSAT1 variants currently listed in ClinVar, gnomAD, and the literature. We anticipate that the assay could be used to comprehensively assess the functional impact of all SNP-accessible amino acid substitution mutations in PSAT1, a resource that could aid variant interpretation and identify potential NLS carriers.
Assuntos
Anormalidades Múltiplas/genética , Encefalopatias/genética , Retardo do Crescimento Fetal/genética , Ictiose/genética , Deformidades Congênitas dos Membros/genética , Microcefalia/genética , Fosfoglicerato Desidrogenase/genética , Anormalidades Múltiplas/metabolismo , Encefalopatias/metabolismo , Retardo do Crescimento Fetal/metabolismo , Humanos , Ictiose/metabolismo , Deformidades Congênitas dos Membros/metabolismo , Microcefalia/metabolismo , Mutação de Sentido Incorreto , Fenótipo , Fosfoglicerato Desidrogenase/deficiência , Saccharomyces cerevisiae/metabolismo , Serina/biossínteseRESUMO
Peters plus syndrome (MIM #261540 PTRPLS), characterized by defects in eye development, prominent forehead, hypertelorism, short stature and brachydactyly, is caused by mutations in the ß3-glucosyltransferase (B3GLCT) gene. Protein O-fucosyltransferase 2 (POFUT2) and B3GLCT work sequentially to add an O-linked glucose ß1-3fucose disaccharide to properly folded thrombospondin type 1 repeats (TSRs). Forty-nine proteins are predicted to be modified by POFUT2, and nearly half are members of the ADAMTS superfamily. Previous studies suggested that O-linked fucose is essential for folding and secretion of POFUT2-modified proteins and that B3GLCT-mediated extension to the disaccharide is essential for only a subset of targets. To test this hypothesis and gain insight into the origin of PTRPLS developmental defects, we developed and characterized two mouse B3glct knockout alleles. Using these models, we tested the role of B3GLCT in enabling function of ADAMTS9 and ADAMTS20, two highly conserved targets whose functions are well characterized in mouse development. The mouse B3glct mutants developed craniofacial and skeletal abnormalities comparable to PTRPLS. In addition, we observed highly penetrant hydrocephalus, white spotting and soft tissue syndactyly. We provide strong genetic and biochemical evidence that hydrocephalus and white spotting in B3glct mutants resulted from loss of ADAMTS20, eye abnormalities from partial reduction of ADAMTS9 and cleft palate from loss of ADAMTS20 and partially reduced ADAMTS9 function. Combined, these results provide compelling evidence that ADAMTS9 and ADAMTS20 were differentially sensitive to B3GLCT inactivation and suggest that the developmental defects in PTRPLS result from disruption of a subset of highly sensitive POFUT2/B3GLCT targets such as ADAMTS20.
Assuntos
Proteínas ADAMTS/metabolismo , Proteína ADAMTS9/metabolismo , Fenda Labial/metabolismo , Córnea/anormalidades , Glicosiltransferases/deficiência , Transtornos do Crescimento/metabolismo , Deformidades Congênitas dos Membros/metabolismo , Alelos , Animais , Fenda Labial/enzimologia , Fenda Labial/genética , Córnea/enzimologia , Córnea/metabolismo , Modelos Animais de Doenças , Feminino , Fucosiltransferases/genética , Fucosiltransferases/metabolismo , Sistema da Enzima Desramificadora do Glicogênio/metabolismo , Glicosiltransferases/genética , Glicosiltransferases/metabolismo , Transtornos do Crescimento/enzimologia , Transtornos do Crescimento/genética , Deformidades Congênitas dos Membros/enzimologia , Deformidades Congênitas dos Membros/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mutação , Organogênese/genéticaRESUMO
BACKGROUND: Geleophysic dysplasia (GPHYSD) is a disorder characterized by dysmorphic features, stiff joints and cardiac involvement due to defects of TGF-ß signaling. GPHYSD can be caused by mutations in FBN1, ADAMTLS2, and LTBP3 genes. METHODS AND RESULTS: Consistent with previous reports, we found intracellular inclusions of unknown material by electron microscopy (EM) in skin fibroblasts of two GPHYSD individuals carrying FBN1 mutations. Moreover, we found that the storage material is enclosed within lysosomes and is associated with the upregulation of several lysosomal genes. Treatment of GPHYSD fibroblasts carrying FBN1 mutations with the angiotensin II receptor type 1 inhibitor losartan that inhibits TGF-ß signaling did not reduce the storage but improved the extracellular deposition of fibrillin-1 microfibrils. CONCLUSION: Losartan is a promising candidate drug for treatment of GPHYSD due to FBN1 defects.
Assuntos
Doenças do Desenvolvimento Ósseo/genética , Doenças do Desenvolvimento Ósseo/metabolismo , Fibrilina-1/genética , Fibroblastos/metabolismo , Deformidades Congênitas dos Membros/genética , Deformidades Congênitas dos Membros/metabolismo , Losartan/farmacologia , Lisossomos/metabolismo , Microfibrilas/metabolismo , Pele/metabolismo , Pele/patologia , Adolescente , Doenças do Desenvolvimento Ósseo/patologia , Criança , Pré-Escolar , Matriz Extracelular , Feminino , Fibroblastos/ultraestrutura , Humanos , Lactente , Deformidades Congênitas dos Membros/patologia , Masculino , Transdução de Sinais/efeitos dos fármacos , Fator de Crescimento Transformador beta/metabolismoRESUMO
Heterozygous missense mutations in several genes in the WNT5A signaling pathway cause autosomal dominant Robinow syndrome 1 (DRS1). Our objective was to clarify the functional impact of a missense mutation in WNT5A on the skeleton, one of the main affected tissues in RS. We delivered avian replication competent retroviruses (RCAS) containing human wild-type WNT5A (wtWNT5A), WNT5AC83S variant or GFP/AlkPO4 control genes to the chicken embryo limb. Strikingly, WNT5AC83S consistently caused a delay in ossification and bones were more than 50% shorter and 200% wider than controls. In contrast, bone dimensions in wtWNT5A limbs were slightly affected (20% shorter, 25% wider) but ossification occurred on schedule. The dysmorphology of bones was established during cartilage differentiation. Instead of stereotypical stacking of chondrocytes, the WNT5AC83S-infected cartilage was composed of randomly oriented chondrocytes and that had diffuse, rather than concentrated Prickle staining, both signs of disrupted planar cell polarity (PCP) mechanisms. Biochemical assays revealed that C83S variant was able to activate the Jun N-terminal kinase-PCP pathway similar to wtWNT5A; however, the activity of the variant ligand was influenced by receptor availability. Unexpectedly, the C83S change caused a reduction in the amount of protein being synthesized and secreted, compared to wtWNT5A. Thus, in the chicken and human, RS phenotypes are produced from the C83S mutation, even though the variant protein is less abundant than wtWNT5A. We conclude the variant protein has dominant-negative effects on chondrogenesis leading to limb abnormalities.
Assuntos
Condrócitos/citologia , Condrogênese , Anormalidades Craniofaciais/metabolismo , Nanismo/metabolismo , Extremidades/embriologia , Deformidades Congênitas dos Membros/metabolismo , Anormalidades Urogenitais/metabolismo , Proteína Wnt-5a/genética , Animais , Animais Geneticamente Modificados , Cartilagem/metabolismo , Polaridade Celular/fisiologia , Embrião de Galinha , Galinhas , Condrogênese/genética , Anormalidades Craniofaciais/genética , Modelos Animais de Doenças , Nanismo/genética , Células HEK293 , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Deformidades Congênitas dos Membros/genética , Mutação de Sentido Incorreto , Fenótipo , Anormalidades Urogenitais/genética , Via de Sinalização Wnt , Proteína Wnt-5a/metabolismoRESUMO
DOCK6 is a RAC1/CDC42 guanine nucleotide exchange factor, however, little is known about its function and sub-cellular localization. DOCK6 regulates the balance between RAC1 and RHOA activity during cell adhesion and is important for CDC42-dependent mitotic chromosome alignment. Surprisingly, a cell intrinsic adaptation mechanism compensates for errors in these DOCK6 functions that arise as a consequence of prolonged DOCK6 depletion or complete removal in DOCK6 knockout cells. Down-regulation of the ubiquitin-like modifier ISG15 accounts for this adaptation. Strikingly, although most other DOCK family proteins are deployed on the plasma membrane, here we show that DOCK6 localizes to the endoplasmic reticulum (ER) in dependence of its DHR-1 domain. ER localization of DOCK6 opens up new insights into its functions.
Assuntos
Membrana Celular/metabolismo , Citocinas/metabolismo , Retículo Endoplasmático/metabolismo , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Ubiquitinas/metabolismo , Membrana Celular/genética , Citocinas/genética , Displasia Ectodérmica/genética , Displasia Ectodérmica/metabolismo , Displasia Ectodérmica/patologia , Retículo Endoplasmático/genética , Técnicas de Silenciamento de Genes , Fatores de Troca do Nucleotídeo Guanina/genética , Células HeLa , Humanos , Deformidades Congênitas dos Membros/genética , Deformidades Congênitas dos Membros/metabolismo , Deformidades Congênitas dos Membros/patologia , Dermatoses do Couro Cabeludo/congênito , Dermatoses do Couro Cabeludo/genética , Dermatoses do Couro Cabeludo/metabolismo , Dermatoses do Couro Cabeludo/patologia , Ubiquitinas/genética , Proteínas rac1 de Ligação ao GTP/genética , Proteínas rac1 de Ligação ao GTP/metabolismo , Proteína rhoA de Ligação ao GTP/genética , Proteína rhoA de Ligação ao GTP/metabolismoAssuntos
Anormalidades Múltiplas/genética , Proteínas de Ligação ao Cálcio/genética , Síndrome de Ellis-Van Creveld/genética , Deformidades Congênitas dos Membros/genética , Mutação de Sentido Incorreto , Proteínas/genética , Anormalidades Dentárias/genética , Anormalidades Múltiplas/metabolismo , Anormalidades Múltiplas/patologia , Proteínas de Ligação ao Cálcio/metabolismo , Clonagem Molecular , Síndrome de Ellis-Van Creveld/metabolismo , Síndrome de Ellis-Van Creveld/patologia , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Células HEK293 , Heterozigoto , Humanos , Peptídeos e Proteínas de Sinalização Intercelular , Deformidades Congênitas dos Membros/metabolismo , Deformidades Congênitas dos Membros/patologia , Linhagem , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Proteínas/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Anormalidades Dentárias/metabolismo , Anormalidades Dentárias/patologia , TransfecçãoRESUMO
Domestic dog breeds exhibit remarkable morphological variations that result from centuries of artificial selection and breeding. Identifying the genetic changes that contribute to these variations could provide critical insights into the molecular basis of tissue and organismal morphogenesis. Bulldogs, French Bulldogs and Boston Terriers share many morphological and disease-predisposition traits, including brachycephalic skull morphology, widely set eyes and short stature. Unlike other brachycephalic dogs, these breeds also exhibit vertebral malformations that result in a truncated, kinked tail (screw tail). Whole genome sequencing of 100 dogs from 21 breeds identified 12.4 million bi-allelic variants that met inclusion criteria. Whole Genome Association of these variants with the breed defining phenotype of screw tail was performed using 10 cases and 84 controls and identified a frameshift mutation in the WNT pathway gene DISHEVELLED 2 (DVL2) (Chr5: 32195043_32195044del, p = 4.37 X 10-37) as the most strongly associated variant in the canine genome. This DVL2 variant was fixed in Bulldogs and French Bulldogs and had a high allele frequency (0.94) in Boston Terriers. The DVL2 variant segregated with thoracic and caudal vertebral column malformations in a recessive manner with incomplete and variable penetrance for thoracic vertebral malformations between different breeds. Importantly, analogous frameshift mutations in the human DVL1 and DVL3 genes cause Robinow syndrome, a congenital disorder characterized by similar craniofacial, limb and vertebral malformations. Analysis of the canine DVL2 variant protein showed that its ability to undergo WNT-induced phosphorylation is reduced, suggesting that altered WNT signaling may contribute to the Robinow-like syndrome in the screwtail breeds.
Assuntos
Anormalidades Craniofaciais/veterinária , Proteínas Desgrenhadas/genética , Doenças do Cão/genética , Cães/genética , Nanismo/veterinária , Deformidades Congênitas dos Membros/veterinária , Anormalidades Urogenitais/veterinária , Sequência de Aminoácidos , Animais , Anormalidades Craniofaciais/genética , Anormalidades Craniofaciais/metabolismo , Proteínas Desgrenhadas/metabolismo , Doenças do Cão/metabolismo , Cães/anatomia & histologia , Cães/classificação , Nanismo/genética , Nanismo/metabolismo , Feminino , Mutação da Fase de Leitura , Variação Genética , Estudo de Associação Genômica Ampla , Humanos , Deformidades Congênitas dos Membros/genética , Deformidades Congênitas dos Membros/metabolismo , Masculino , Compostos de Organossilício , Homologia de Sequência de Aminoácidos , Especificidade da Espécie , Cauda/anatomia & histologia , Anormalidades Urogenitais/genética , Anormalidades Urogenitais/metabolismo , Via de Sinalização Wnt/genéticaRESUMO
Neu-Laxova syndrome (NLS) is a very rare autosomal recessive congenital disorder characterized by disturbed development of the central nervous system and the skin and caused by mutations in any of the three genes involved in de novo l-serine biosynthesis: PHGDH, PSAT1, and PSPH l-Serine is essential for the biosynthesis of phosphatidylserine and sphingolipids. The extracellular lipid of the stratum corneum, of which sphingolipid constitutes a significant part, plays a primary role in skin barrier function. Here, we describe a Japanese NLS pedigree with a previously unreported nonsense mutation in PHGDH and a unique inversion of chromosome 1. In addition, the levels of 11 major ceramide classes in the tape-stripped stratum corneum of the NLS patient's skin were assessed by LC/MS. Notably, lower amounts of ceramides of all classes were found in the patient's stratum corneum than in those of controls. This is the first report to demonstrate the reduction of ceramides in the stratum corneum of an NLS patient due to PHGDH mutations. The clinical findings and a detailed analysis of ceramides from the stratum corneum in the family extend the spectrum of clinical anomalies and give us a clue to the pathomechanisms of ichthyosis in NLS patients with phosphoglycerate dehydrogenase deficiency.
Assuntos
Anormalidades Múltiplas/metabolismo , Encefalopatias/metabolismo , Erros Inatos do Metabolismo dos Carboidratos/metabolismo , Ceramidas/metabolismo , Retardo do Crescimento Fetal/metabolismo , Ictiose/metabolismo , Deformidades Congênitas dos Membros/metabolismo , Microcefalia/metabolismo , Fosfoglicerato Desidrogenase/deficiência , Fosfoglicerato Desidrogenase/metabolismo , Transtornos Psicomotores/metabolismo , Convulsões/metabolismo , Adulto , Aminoácidos/metabolismo , Feminino , Idade Gestacional , Humanos , Imuno-Histoquímica , Recém-Nascido , Masculino , Gravidez , Esfingolipídeos/metabolismo , Sequenciamento do Exoma , Adulto JovemRESUMO
The Notch signaling pathway is highly conserved and essential for animal development. It is required for cell differentiation, survival, and proliferation. Regulation of Notch signaling is a crucial process for human health. Ligands initiate a signal cascade by binding to Notch receptors expressed on a neighboring cell. Notch receptors interact with ligands through their epidermal growth factor-like repeats (EGF repeats). Most EGF repeats are modified by O-glycosylation with residues such as O-linked N-acetylglucosamine (O-GlcNAc), O-fucose, and O-glucose. These O-glycan modifications are important for Notch function. Defects in O-glycosylation affect Notch-ligand interaction, trafficking of Notch receptors, and Notch stability on the cell surface. Although the roles of each modification are not fully understood, O-fucose is essential for binding of Notch receptors to their ligands. We reported an EGF domain-specific O-GlcNAc transferase (EOGT) localized in the endoplasmic reticulum. Mutations in genes encoding EOGT or NOTCH1 cause Adams-Oliver syndrome. Dysregulation of Notch signaling because of defects or mutations in Notch receptors or Notch signal-regulating proteins, such as glycosyltransferases, induce a variety of congenital disorders. In this review, we discuss O-glycosylation of Notch receptors and congenital human diseases caused by defects in O-glycans on Notch receptors.
Assuntos
Receptores Notch/metabolismo , Animais , Displasia Ectodérmica/metabolismo , Fator de Crescimento Epidérmico/metabolismo , Glicosilação , Humanos , Deformidades Congênitas dos Membros/metabolismo , N-Acetilglucosaminiltransferases/metabolismo , Dermatoses do Couro Cabeludo/congênito , Dermatoses do Couro Cabeludo/metabolismoRESUMO
Ribosome biogenesis is a global process required for growth and proliferation in all cells, but disruptions in this process surprisingly lead to tissue-specific phenotypic disorders termed ribosomopathies. Pathogenic variants in the RNA Polymerase (Pol) I subunit POLR1A cause Acrofacial Dysostosis-Cincinnati type, which is characterized by craniofacial and limb anomalies. In a zebrafish model of Acrofacial Dysostosis-Cincinnati type, we demonstrate that polr1a-/- mutants exhibit deficient 47S rRNA transcription, reduced monosomes and polysomes and, consequently, defects in protein translation. This results in Tp53-dependent neuroepithelial apoptosis, diminished neural crest cell proliferation and cranioskeletal anomalies. This indicates that POLR1A is critical for rRNA transcription, which is considered a rate limiting step in ribosome biogenesis, underpinning its requirement for neuroepithelial cell and neural crest cell proliferation and survival. To understand the contribution of the Tp53 pathway to the pathogenesis of Acrofacial Dysostosis-Cincinnati type, we genetically inhibited tp53 in polr1a-/- mutant embryos. Tp53 inhibition suppresses neuroepithelial apoptosis and partially ameliorates the polr1a mutant phenotype. However, complete rescue of cartilage development is not observed due to the failure to improve rDNA transcription and neural crest cell proliferation. Altogether, these data reveal specific functions for both Tp53-dependent and independent signaling downstream of polr1a in ribosome biogenesis during neural crest cell and craniofacial development, in the pathogenesis of Acrofacial Dysostosis-Cincinnati type. Furthermore, our work sets the stage for identifying Tp53-independent therapies to potentially prevent Acrofacial dysostosis-Cincinnati type and other similar ribosomopathies.
Assuntos
Deformidades Congênitas dos Membros/metabolismo , Disostose Mandibulofacial/metabolismo , Crista Neural/patologia , Proteína Supressora de Tumor p53/metabolismo , Proteínas de Peixe-Zebra/metabolismo , Animais , Diferenciação Celular/genética , Proliferação de Células/genética , Modelos Animais de Doenças , Embrião não Mamífero , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Deformidades Congênitas dos Membros/patologia , Disostose Mandibulofacial/patologia , Mutação , RNA Polimerase I/genética , RNA Polimerase I/metabolismo , Transdução de Sinais , Proteína Supressora de Tumor p53/genética , Peixe-Zebra/embriologia , Peixe-Zebra/genética , Proteínas de Peixe-Zebra/genéticaRESUMO
Feingold syndrome is a skeletal dysplasia caused by loss-of-function mutations of either MYCN (type 1) or MIR17HG that encodes miR-17-92 microRNAs (type 2). Since miR-17-92 expression is transcriptionally regulated by MYC transcription factors, it has been postulated that Feingold syndrome type 1 and 2 may be caused by a common molecular mechanism. Here we show that Mir17-92 deficiency upregulates TGF-ß signaling, whereas Mycn-deficiency downregulates PI3K signaling in limb mesenchymal cells. Genetic or pharmacological inhibition of TGF-ß signaling efficiently rescues the skeletal defects caused by Mir17-92 deficiency, suggesting that upregulation of TGF-ß signaling is responsible for the skeletal defect of Feingold syndrome type 2. By contrast, the skeletal phenotype of Mycn-deficiency is partially rescued by Pten heterozygosity, but not by TGF-ß inhibition. These results strongly suggest that despite the phenotypical similarity, distinct molecular mechanisms underlie the pathoetiology for Feingold syndrome type 1 and 2.
Assuntos
Pálpebras/anormalidades , Deficiência Intelectual/genética , Deformidades Congênitas dos Membros/genética , MicroRNAs/genética , Microcefalia/genética , Proteína Proto-Oncogênica N-Myc/genética , Transdução de Sinais/genética , Fístula Traqueoesofágica/genética , Animais , Modelos Animais de Doenças , Pálpebras/metabolismo , Pálpebras/patologia , Feminino , Regulação da Expressão Gênica , Heterozigoto , Humanos , Deficiência Intelectual/metabolismo , Deficiência Intelectual/patologia , Deformidades Congênitas dos Membros/metabolismo , Deformidades Congênitas dos Membros/patologia , Masculino , Camundongos , Camundongos Knockout , MicroRNAs/metabolismo , Microcefalia/metabolismo , Microcefalia/patologia , Proteína Proto-Oncogênica N-Myc/deficiência , PTEN Fosfo-Hidrolase/genética , PTEN Fosfo-Hidrolase/metabolismo , Fator de Transcrição STAT3/genética , Fator de Transcrição STAT3/metabolismo , Fístula Traqueoesofágica/metabolismo , Fístula Traqueoesofágica/patologia , Fator de Crescimento Transformador beta1/genética , Fator de Crescimento Transformador beta1/metabolismoRESUMO
Macrodactyly is a congenital disease characterized by aggressive overgrowth of adipose tissue in digits or limbs frequently accompanied with hyperostosis and nerve enlargement; its pathological mechanism is poorly understood. Adipose-derived stem cells (ASCs) have been extensively studied in tissue engineering and regenerative medicine as an ideal alternative substitute for bone marrow-derived mesenchymal stem cells (BM-MSCs), but their pathological role is largely unknown. In this study, ASCs from macrodactyly adipose tissues (Mac-ASCs) were isolated and compared to ASCs derived from the normal abdominal subcutaneous adipose tissue (Sat-ASCs) for cell morphology, surface marker expression, proliferation rate, and tri-lineage differentiation potential. Despite similar cell morphology and cell surface marker expression, Mac-ASCs showed higher cell proportion in the S phase and increased proliferation compared with Sat-ASCs. Moreover, osteogenic and chondrogenic differentiation capacities were enhanced in Mac-ASCs, with reduced adipogenic potential. In addition, the expression levels of adipogenic genes were lower in undifferentiated Mac-ASCs than in Sat-ASCs. These findings unraveled enhanced proliferation activity, a regression in the differentiation stage, and greater potentiality of ASCs in macrodactyly, which could contribute to hyperostosis and nerve enlargement in addition to adipose tissue overgrowth in patients.
Assuntos
Tecido Adiposo/citologia , Dedos/anormalidades , Deformidades Congênitas dos Membros/diagnóstico , Deformidades Congênitas dos Membros/metabolismo , Fenótipo , Células-Tronco/citologia , Células-Tronco/metabolismo , Adipócitos/citologia , Adipócitos/metabolismo , Adipogenia/genética , Tecido Adiposo/metabolismo , Tecido Adiposo/patologia , Biomarcadores , Diferenciação Celular/genética , Proliferação de Células , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica , Humanos , ImunofenotipagemRESUMO
The most impressive phenotypic appearance of sirenomelia is the presence of a 180°-rotated, axially positioned, single lower limb. Associated gastrointestinal and genitourinary anomalies are almost always present. This rare anomaly is still the subject of ongoing controversies concerning its nosology, pathogenesis, and possible genetic etiology. Sirenomelia can be part of a syndromic continuum, overlapping with other complex conditions including caudal dysgenesis and VATER/VACTERL/VACTERL-H associations, which could all be part of a heterogeneous spectrum, and originate from an early defect in blastogenesis. It is imaginable that different "primary field defects," whether or not genetically based, induce a spectrum of caudal malformations. In the current study, we review the contemporary hypotheses and conceptual approaches regarding the etiology and pathogenesis of sirenomelia, especially in the context of concomitant conditions. To expand on the latter, we included the external and internal dysmorphology of one third trimester sirenomelic fetus from our anatomical museum collection, in which multiple concomitant but discordant anomalies were observed compared with classic sirenomelia, and was diagnosed as VACTERL-H association with sirenomelia. Birth Defects Research 109:791-804, 2017. © 2017 The Authors. Birth Defects Research Published by Wiley Periodicals, Inc.