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1.
Cell ; 142(5): 787-99, 2010 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-20813264

RESUMO

The complexity of organogenesis hinders in vitro generation of organs derived from a patient's pluripotent stem cells (PSCs), an ultimate goal of regenerative medicine. Mouse wild-type PSCs injected into Pdx1(-/-) (pancreatogenesis-disabled) mouse blastocysts developmentally compensated vacancy of the pancreatic "developmental niche," generating almost entirely PSC-derived pancreas. To examine the potential for xenogenic approaches in blastocyst complementation, we injected mouse or rat PSCs into rat or mouse blastocysts, respectively, generating interspecific chimeras and thus confirming that PSCs can contribute to xenogenic development between mouse and rat. The development of these mouse/rat chimeras was primarily influenced by host blastocyst and/or foster mother, evident by body size and species-specific organogenesis. We further injected rat wild-type PSCs into Pdx1(-/-) mouse blastocysts, generating normally functioning rat pancreas in Pdx1(-/-) mice. These data constitute proof of principle for interspecific blastocyst complementation and for generation in vivo of organs derived from donor PSCs using a xenogenic environment.


Assuntos
Blastocisto , Quimera/embriologia , Pâncreas/citologia , Pâncreas/embriologia , Células-Tronco Pluripotentes , Animais , Diabetes Mellitus/induzido quimicamente , Diabetes Mellitus/terapia , Desenvolvimento Embrionário , Técnicas de Introdução de Genes , Proteínas de Homeodomínio/genética , Camundongos , Camundongos Endogâmicos , Organogênese , Ratos , Ratos Wistar , Transativadores/genética
2.
Int J Obes (Lond) ; 2024 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-39277655

RESUMO

BACKGROUND: Metabolic dysfunction-associated steatotic liver disease (MASLD) is considered multifactorial with a number of predisposing gene polymorphisms known. METHODS: The occurrence of MASLD in 7 and 10 year old siblings, one without classical risk factors and one with type 2 diabetes suggested a monogenic etiology and prompted next-generation sequencing. Exome sequencing was performed in the proband, both parents and both siblings. The impact of a likely disease-causing DNA variant was assessed on the transcript and protein level. RESULTS: Two siblings have hepatomegaly, elevated serum transaminase activity, and steatosis and harbor a homozygous DECR1 splice-site variant, c.330+3A>T. The variant caused DECR1 transcript decay. Immunostaining demonstrated lack of DECR1 in patient liver. CONCLUSIONS: These patients may represent the first individuals with DECR1 deficiency, then defining within MASLD an autosomal-recessive entity, well corresponding to the reported steatotic liver disease in Decr1 knockout mice. DECR1 may need to be considered in the genetic work-up of MASLD.

3.
Clin Genet ; 106(3): 224-233, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38553872

RESUMO

Exome sequencing (ES) has identified biallelic kinesin family member 12 (KIF12) mutations as underlying neonatal cholestatic liver disease. We collected information on onset and progression of this entity. Among consecutively referred pediatric patients at our centers, diagnostic ES identified 4 patients with novel, biallelic KIF12 variants using the human GRCh38 reference sequence, as KIF12 remains incompletely annotated in the older reference sequence GRCh37. A review of these and of 21 reported patients with KIF12 variants found that presentation with elevated serum transaminase activity in the context of trivial respiratory infection, without clinical features of liver disease, was more common (n = 18) than manifest cholestatic disease progressing rapidly to liver transplantation (LT; n = 7). Onset of liver disease was at age <1 year in 15 patients; LT was more common in this group. Serum gamma-glutamyl transpeptidase activity (GGT) was elevated in all patients, and total bilirubin was elevated in 15 patients. Liver fibrosis or cirrhosis was present in 14 of 18 patients who were biopsied. The 16 different pathogenic variants and 11 different KIF12 genotypes found were not correlated with age of onset or progression to LT. Identification of biallelic pathogenic KIF12 variants distinguishes KIF12-related disease from other entities with elevated GGT.


Assuntos
Cinesinas , Hepatopatias , Mutação , gama-Glutamiltransferase , Humanos , Cinesinas/genética , gama-Glutamiltransferase/sangue , gama-Glutamiltransferase/genética , Masculino , Feminino , Hepatopatias/genética , Hepatopatias/patologia , Lactente , Sequenciamento do Exoma , Recém-Nascido , Predisposição Genética para Doença , Transplante de Fígado , Genótipo , Alelos , Pré-Escolar , Criança
4.
Liver Int ; 43(5): 1089-1095, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36938759

RESUMO

Neonatal sclerosing cholangitis (NSC) is associated with progressing biliary fibrosis that often requires liver transplantation in childhood. Several recent studies have identified variants in DCDC2, encoding doublecortin domain-containing protein 2 (DCDC2), expressed in primary cilia, that accompany syndromic disease and NSC. We report four patients with hepatobiliary disease associated with two novel homozygous or compound heterozygous variants in DCDC2. Three patients with protein-truncating variants in DCDC2, expressing no DCDC2, presented with the originally described severe hepatic phenotype in infancy. One patient with a novel homozygous DCDC2 missense variant shows a markedly milder phenotype only manifest in childhood and with retained DCDC2 expression. Concomitant nephronophthisis is present in three patients and learning disability in two. This report widens the phenotypic spectrum of DCDC2-associated hepatobiliary disease. Testing for DCDC2 expression and DCDC2 variants should be included in the evaluation of cholangiopathy of unknown aetiology in childhood as well as in infancy.


Assuntos
Colestase , Humanos , Colangite Esclerosante/genética , Colestase/genética , Homozigoto , Hepatopatias , Proteínas Associadas aos Microtúbulos/metabolismo , Fenótipo
5.
Brain ; 144(10): 3036-3049, 2021 11 29.
Artigo em Inglês | MEDLINE | ID: mdl-34037727

RESUMO

Golgi-associated retrograde protein (GARP) and endosome-associated recycling protein (EARP) complexes are membrane-tethering heterotetramers located at the trans-Golgi network and recycling endosomes, respectively. GARP and EARP share the three subunits VPS51, VPS52 and VPS53, while VPS50 is unique to EARP and VPS54 to GARP. Retrograde transport of endosomal cargos to the trans-Golgi network is mediated by GARP and endocytic recycling by EARP. Here we report two unrelated individuals with homozygous variants in VPS50, a splice variant (c.1978-1G>T) and an in-frame deletion (p.Thr608del). Both patients had severe developmental delay, postnatal microcephaly, corpus callosum hypoplasia, seizures and irritability, transient neonatal cholestasis and failure to thrive. Light and transmission electron microscopy of liver from one revealed the absence of gamma-glutamyltransferase at bile canaliculi, with mislocalization to basolateral membranes and abnormal tight junctions. Using patient-derived fibroblasts, we identified reduced VPS50 protein accompanied by reduced levels of VPS52 and VPS53. While the transferrin receptor internalization rate was normal in cells of both patients, recycling of the receptor to the plasma membrane was significantly delayed. These data underscore the importance of VPS50 and/or the EARP complex in endocytic recycling and suggest an additional function in establishing cell polarity and trafficking between basolateral and apical membranes in hepatocytes. Individuals with biallelic hypomorphic variants in VPS50, VPS51 or VPS53 show an overarching neurodegenerative disorder with severe developmental delay, intellectual disability, microcephaly, early-onset epilepsy and variable atrophy of the cerebellum, cerebrum and/or brainstem. The term 'GARP/EARP deficiency' designates disorders in such individuals.


Assuntos
Colestase/diagnóstico , Colestase/genética , Variação Genética/genética , Transtornos do Neurodesenvolvimento/diagnóstico , Transtornos do Neurodesenvolvimento/genética , Proteínas de Transporte Vesicular/genética , Alelos , Células Cultivadas , Pré-Escolar , Colestase/complicações , Humanos , Lactente , Recém-Nascido , Masculino , Transtornos do Neurodesenvolvimento/complicações , Linhagem , Proteínas de Transporte Vesicular/metabolismo , Rede trans-Golgi/fisiologia
6.
Pediatr Transplant ; 26(6): e14318, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35633129

RESUMO

BACKGROUND: Cerebrotendinous xanthomatosis (CTX) is a disorder of bile acid (BA) metabolism due to biallelic mutations in CYP27A1. The deposition of cholesterol and cholestanol in multiple tissues results, manifesting as neurologic disease in adults or older children. Neonatal cholestasis (NC) as a presentation of CTX is rare; it may self-resolve or persist, evolving to require liver transplantation (LT). METHODS: We present in the context of similar reports an instance of CTX manifest as NC and requiring LT. RESULTS: A girl aged 4mo was evaluated for NC with normal serum gamma-glutamyl transpeptidase activity. An extensive diagnostic work-up, including liver biopsy, identified no etiology. Rapid progression to end-stage liver disease required LT aged 5mo. The explanted liver showed hepatocyte loss and micronodular cirrhosis. Bile salt export pump (BSEP), encoded by ABCB11, was not demonstrable immunohistochemically. Both severe ABCB11 disease and NR1H4 disease-NR1H4 encodes farsenoid-X receptor, necessary for ABCB11 transcription-were considered. However, selected liver disorder panel sequencing and mass-spectrometry urinary BA profiling identified CTX, with homozygosity for the predictedly pathogenic CYP27A1 variant c.646G > C p.(Ala216Pro). Variation in other genes associated with intrahepatic cholestasis was not detected. Immunohistochemical study of the liver-biopsy specimen found marked deficiency of CYP27A1 expression; BSEP expression was unremarkable. Aged 2y, the girl is free from neurologic disease. CONCLUSIONS: Bile acid synthesis disorders should be routinely included in the NC/"neonatal hepatitis" work-up. The mutually supportive triple approach of BA profiling, immunohistochemical study, and genetic analysis may optimally address diagnosis in CTX, a treatable disease with widely varying presentation.


Assuntos
Colestase , Falência Hepática , Transplante de Fígado , Xantomatose Cerebrotendinosa , Adolescente , Ácidos e Sais Biliares , Criança , Colestase/diagnóstico , Colestase/etiologia , Colestase/cirurgia , Feminino , Humanos , Lactente , Recém-Nascido , Falência Hepática/complicações , Xantomatose Cerebrotendinosa/complicações , Xantomatose Cerebrotendinosa/diagnóstico , Xantomatose Cerebrotendinosa/genética
7.
J Med Genet ; 58(8): 514-525, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-32737136

RESUMO

BACKGROUND: For many children with intrahepatic cholestasis and high-serum gamma-glutamyl transferase (GGT) activity, a genetic aetiology of hepatobiliary disease remains undefined. We sought to identify novel genes mutated in children with idiopathic high-GGT intrahepatic cholestasis, with clinical, histopathological and functional correlations. METHODS: We assembled a cohort of 25 children with undiagnosed high-GGT cholestasis and without clinical features of biliary-tract infection or radiological features of choledochal malformation, sclerosing cholangitis or cholelithiasis. Mutations were identified through whole-exome sequencing and targeted Sanger sequencing. We reviewed histopathological findings and assessed phenotypical effects of ZFYVE19 deficiency in cultured cells by immunofluorescence microscopy. RESULTS: Nine Han Chinese children harboured biallelic, predictedly complete loss-of-function pathogenic mutations in ZFYVE19 (c.314C>G, p.S105X; c.379C>T, p.Q127X; c.514C>T, p.R172X; c.547C>T, p.R183X; c.226A>G, p.M76V). All had portal hypertension and, at liver biopsy, histopathological features of the ductal plate malformation (DPM)/congenital hepatic fibrosis (CHF). Four children required liver transplantation for recurrent gastrointestinal haemorrhage. DPM/CHF was confirmed at hepatectomy, with sclerosing small-duct cholangitis. Immunostaining for two primary-cilium axonemal proteins found expression that was deficient intraluminally and ectopic within cholangiocyte cytoplasm. ZFYVE19 depletion in cultured cells yielded abnormalities of centriole and axoneme. CONCLUSION: Biallelic ZFYVE19 mutations can lead to high-GGT cholestasis and DPM/CHF in vivo. In vitro, they can lead to centriolar and axonemal abnormalities. These observations indicate that mutation in ZFYVE19 results, through as yet undefined mechanisms, in a ciliopathy.


Assuntos
Colangite Esclerosante/genética , Colestase Intra-Hepática/genética , Mutação/genética , Proteínas Oncogênicas/genética , Alelos , Sequência de Aminoácidos , Linhagem Celular Tumoral , Doenças Genéticas Inatas , Células HeLa , Humanos , Cirrose Hepática , Sequenciamento do Exoma/métodos
8.
Hum Mutat ; 41(2): 502-511, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31696999

RESUMO

To assess the spectrum of pediatric clinical phenotypes in TJP2 disease, we reviewed records of our seven patients in whom intrahepatic cholestasis was associated with biallelic TJP2 variants (13; 12 novel) and correlated clinical manifestations with mutation type. The effect of a splicing variant was analyzed with a minigene assay. The effects of three missense variants were analyzed with protein expression in vitro. Our patients had both remitting and persistent cholestasis. Three exhibited growth retardation. Six responded to treatment with cholestyramine, ursodeoxycholic acid, or both. Two had cholecystolithiasis. None required liver transplantation or developed hepatocellular or cholangiocellular malignancy. None manifested extrahepatic disease not attributable to effects of cholestasis. The variant c.2180-5T>G resulted in exon 15 skipping with in-frame deletion of 32 amino acid residues in TJP2. The three missense variants decreased but did not abolish TJP2 expression. Patients with truncating or canonical splice-site variants had clinically more severe disease. TJP2 disease in children includes a full clinical spectrum of severity, with mild or intermittent forms as well as the severe and minimal forms hitherto described. Biallelic TJP2 variants must be considered in children with clinically intermittent or resolved intrahepatic cholestasis.


Assuntos
Colestase Intra-Hepática/diagnóstico , Colestase Intra-Hepática/genética , Predisposição Genética para Doença , Variação Genética , Proteína da Zônula de Oclusão-2/genética , Idade de Início , Alelos , Substituição de Aminoácidos , Biópsia , Biologia Computacional/métodos , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Mutação , Linhagem , Splicing de RNA , Sequenciamento do Exoma
9.
Liver Int ; 40(11): 2788-2796, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32808743

RESUMO

BACKGROUND & AIMS: ABCB11 deficiency presenting in infancy is believed generally to manifest as persistent/progressive cholestasis. We describe a group of patients with biallelic ABCB11 variants whose disorder manifested as transient neonatal cholestasis (TNC). METHODS: Neonatal intrahepatic cholestasis in 68 children (31 males) with biallelic predictedly pathogenic variants (PPV) in ABCB11 was classified as transient (TNC group, n = 23, 11 males), intermittent (benign recurrent intrahepatic cholestasis [BRIC] group, n = 3, 1 male) or persistent/ progressive (progressive familial intrahepatic cholestasis [PFIC] group, n = 42, 19 males). Clinical, genetic and bile salt export pump (BSEP) expression information was correlated with outcomes. RESULTS: The median onset age of jaundice was 3 days (birth to 2 months) for the TNC group and 10.5 days (birth to 3 months) for the PFIC group (P = .034). The median length of follow-up of TNC patients was 44 months (12 months-168 months). At presentation, hepatobiliary-injury biomarker values were similar between the groups (P > .05). TNC patients (17/23) more often than PFIC patients (20/42, P = .041) harboured biallelic non-null variants (predicted not to terminate translation prematurely). TNC patient livers (7/7) more often than PFIC patient livers (5/16, P = .005) expressed immunohistochemically detectable BSEP. Kaplan-Meier analysis showed better prognosis for patients with BSEP expression (P = .009). Too few BRIC patients were available for statistical study. CONCLUSIONS: Neonatal cholestasis associated with biallelic PPV in ABCB11 can resolve temporarily or persistently in one third of cases. Resolution is more likely in patients with biallelic non-null PPV or with liver BSEP expression.


Assuntos
Colestase Intra-Hepática , Colestase , Membro 11 da Subfamília B de Transportadores de Cassetes de Ligação de ATP/genética , Transportadores de Cassetes de Ligação de ATP/genética , Criança , Colestase/genética , Colestase Intra-Hepática/diagnóstico , Colestase Intra-Hepática/genética , Genótipo , Humanos , Lactente , Recém-Nascido , Masculino , Mutação
10.
Liver Int ; 40(5): 1142-1150, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32124521

RESUMO

BACKGROUND & AIMS: In about 20% of children with cholestasis and normal or low serum gamma-glutamyltransferase (GGT) activity, no aetiology is identified. We sought new genes implicated in paediatric hepatobiliary disease. METHODS: We conducted whole-exome sequencing in 69 children evaluated at our centre from 2011 to 2018 who had low-GGT cholestasis and in whom homozygous/compound heterozygous predictedly pathogenic variants (PPVs) in ATP8B1, ABCB11, NR1H4, MYO5B or TJP2 were not found. Clinical records and findings on light microscopy and transmission electron microscopy of liver biopsy materials were reviewed. RESULTS: In seven patients from seven unrelated families, biallelic PPVs (10 in total) were found in USP53, recently associated with intrahepatic cholestasis. Seven variants were classified as pathogenic: one canonical splicing, c.569 + 2T > C, and six nonsense or frameshifting: c.169C > T (p.Arg57Ter), c.581delA (p.Arg195GlufsTer38), c.831_832insAG (p.Val279GlufsTer16), c.1012C > T (p.Arg338Ter), c.1426C > T (p.Arg476Ter) and c.1558C > T (p.Arg520Ter). Three were likely pathogenic: c.297G > T (p.Arg99Ser), c.395A > G (p.His132Arg) and c.878G > T (p.Gly293Val). In all patients, jaundice began at age <7 months. Cholestasis was transient, with documented resolution of hyperbilirubinaemia in all (oldest patient now aged 5 years) except one, who was lost to follow-up. Light microscopy identified intralobular cholestasis, giant-cell change of hepatocytes and perisinusoidal-perihepatocytic and portal-tract fibrosis. Ultrastructural study revealed elongated hepatocyte-hepatocyte tight junctions. One patient was deaf. CONCLUSION: USP53 interacts with the tight junction constituent TJP2. TJP2 mutation can cause low-GGT intrahepatic cholestasis, with elongated hepatocyte-hepatocyte tight junctions, as well as deafness. Our findings extend a preliminary report of USP53 disease and indicate that USP53 mutation may generate a partial phenocopy of TJP2 disease.


Assuntos
Colestase Intra-Hepática , Colestase , Proteases Específicas de Ubiquitina , Criança , Colestase/genética , Colestase Intra-Hepática/genética , Hepatócitos , Humanos , Lactente , Mutação , Proteases Específicas de Ubiquitina/genética , gama-Glutamiltransferase
11.
Am J Hum Genet ; 99(2): 414-22, 2016 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-27426735

RESUMO

tRNA synthetase deficiencies are a growing group of genetic diseases associated with tissue-specific, mostly neurological, phenotypes. In cattle, cytosolic isoleucyl-tRNA synthetase (IARS) missense mutations cause hereditary weak calf syndrome. Exome sequencing in three unrelated individuals with severe prenatal-onset growth retardation, intellectual disability, and muscular hypotonia revealed biallelic mutations in IARS. Studies in yeast confirmed the pathogenicity of identified mutations. Two of the individuals had infantile hepatopathy with fibrosis and steatosis, leading in one to liver failure in the course of infections. Zinc deficiency was present in all affected individuals and supplementation with zinc showed a beneficial effect on growth in one.


Assuntos
Alelos , Retardo do Crescimento Fetal/genética , Deficiência Intelectual/genética , Isoleucina-tRNA Ligase/genética , Hepatopatias/congênito , Hepatopatias/genética , Hipotonia Muscular/congênito , Hipotonia Muscular/genética , Mutação , Adolescente , Animais , Criança , Pré-Escolar , Suplementos Nutricionais , Fígado Gorduroso/genética , Feminino , Fibrose/genética , Humanos , Lactente , Recém-Nascido , Isoleucina-tRNA Ligase/deficiência , Falência Hepática/genética , Masculino , Síndrome , Peixe-Zebra/genética , Zinco/administração & dosagem , Zinco/deficiência , Zinco/uso terapêutico
13.
J Pediatr Gastroenterol Nutr ; 68(1): e1-e6, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30589726

RESUMO

Mutations in the nuclear gene DGUOK, encoding deoxyguanosine kinase, cause an infantile hepatocerebral type of mitochondrial depletion syndrome (MDS). We report 6 MDS patients harboring bi-allelic DGUOK mutations, of which 3 are novel, including a large intragenic Austrian founder deletion. One patient was diagnosed with hepatocellular carcinoma aged 6 months, supporting a link between mitochondrial DNA depletion and tumorigenesis; liver transplantation proved beneficial with regard to both tumor treatment and psychomotor development.


Assuntos
Doenças Mitocondriais/genética , Áustria , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/cirurgia , DNA Mitocondrial/genética , Feminino , Humanos , Lactente , Recém-Nascido , Fígado/patologia , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/cirurgia , Transplante de Fígado , Masculino , Doenças Mitocondriais/patologia , Doenças Mitocondriais/cirurgia , Mutação
15.
Pediatr Dev Pathol ; 22(4): 365-369, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30497332

RESUMO

Hepatic mesenchymal hamartoma is a rare benign neoplasm principally encountered in young children. Its origin is unknown. We report an unusual hepatic mesenchymal hamartoma in a 7-month-old girl, including histopathologic findings, immunophenotype, and karyotype. Chromosomal microarray analysis of tumoral tissue and circulating lymphocytes found 4 copies of a segment at 1q44 and fluorescence in situ hybridization indicated tandem triplication, ascribed to expansion of a paternal tandem duplication. This genetic abnormality may have played a role in pathogenesis.


Assuntos
Hamartoma/genética , Neoplasias Hepáticas/genética , Cariótipo Anormal , Feminino , Hamartoma/diagnóstico por imagem , Hamartoma/patologia , Humanos , Imunofenotipagem , Hibridização in Situ Fluorescente , Lactente , Neoplasias Hepáticas/diagnóstico por imagem , Neoplasias Hepáticas/patologia , Mesoderma/diagnóstico por imagem , Mesoderma/patologia
16.
Hepatology ; 65(5): 1655-1669, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28027573

RESUMO

Hereditary cholestasis in childhood and infancy with normal serum gamma-glutamyltransferase (GGT) activity is linked to several genes. Many patients, however, remain genetically undiagnosed. Defects in myosin VB (MYO5B; encoded by MYO5B) cause microvillus inclusion disease (MVID; MIM251850) with recurrent watery diarrhea. Cholestasis, reported as an atypical presentation in MVID, has been considered a side effect of parenteral alimentation. Here, however, we report on 10 patients who experienced cholestasis associated with biallelic, or suspected biallelic, mutations in MYO5B and who had neither recurrent diarrhea nor received parenteral alimentation. Seven of them are from two study cohorts, together comprising 31 undiagnosed low-GGT cholestasis patients; 3 are sporadic. Cholestasis in 2 patients was progressive, in 3 recurrent, in 2 transient, and in 3 uncategorized because of insufficient follow-up. Liver biopsy specimens revealed giant-cell change of hepatocytes and intralobular cholestasis with abnormal distribution of bile salt export pump (BSEP) at canaliculi, as well as coarse granular dislocation of MYO5B. Mass spectrometry of plasma demonstrated increased total bile acids, primary bile acids, and conjugated bile acids, with decreased free bile acids, similar to changes in BSEP-deficient patients. Literature review revealed that patients with biallelic mutations predicted to eliminate MYO5B expression were more frequent in typical MVID than in isolated-cholestasis patients (11 of 38 vs. 0 of 13). CONCLUSION: MYO5B deficiency may underlie 20% of previously undiagnosed low-GGT cholestasis. MYO5B deficiency appears to impair targeting of BSEP to the canalicular membrane with hampered bile acid excretion, resulting in a spectrum of cholestasis without diarrhea. (Hepatology 2017;65:1655-1669).


Assuntos
Subfamília B de Transportador de Cassetes de Ligação de ATP/deficiência , Colestase Intra-Hepática/genética , Cadeias Pesadas de Miosina/genética , Miosina Tipo V/genética , Subfamília B de Transportador de Cassetes de Ligação de ATP/sangue , Subfamília B de Transportador de Cassetes de Ligação de ATP/genética , Membro 11 da Subfamília B de Transportadores de Cassetes de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/metabolismo , Ácidos e Sais Biliares/sangue , Colestase Intra-Hepática/sangue , Colestase Intra-Hepática/patologia , Análise Mutacional de DNA , Exoma , Feminino , Humanos , Lactente , Recém-Nascido , Fígado/metabolismo , Fígado/patologia , Masculino , Cadeias Pesadas de Miosina/metabolismo , Miosina Tipo V/metabolismo , Estudos Retrospectivos
17.
Liver Int ; 38(9): 1676-1685, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29412511

RESUMO

BACKGROUND & AIMS: Genetic defects causing dysfunction in bile salt export pump (BSEP/ABCB11) lead to liver diseases. ABCB11 mutations alter the bile acid metabolome. We asked whether profiling plasma bile acids could reveal compensatory mechanisms and track genetic and clinical status. METHODS: We compared plasma bile acids in 17 ABCB11-mutated patients, 35 healthy controls and 12 genetically undiagnosed cholestasis patients by ultra-high-performance liquid chromatography/multiple-reaction monitoring-mass spectrometry (UPLC/MRM-MS). We developed an index to rank bile acid hydrophobicity, and thus toxicity, based on LC retention times. We recruited 42 genetically diagnosed hereditary cholestasis patients, of whom 12 were presumed to have impaired BSEP function but carried mutations in genes other than ABCB11, and 8 healthy controls, for further verification. RESULTS: The overall hydrophobicity indices of total bile acids in both the ABCB11-mutated group (11.89 ± 1.07 min) and the undiagnosed cholestasis group (11.46 ± 1.07 min) were lower than those of healthy controls (13.69 ± 0.77 min) (both p < 0.005). This was owing to increased bile acid modifications. Secondary bile acids were detected in patients without BSEP expression, suggesting biliary bile acid secretion through alternative routes. A diagnostic panel comprising lithocholic acid (LCA), tauro-LCA, glyco-LCA and hyocholic acid was identified that could differentiate the ABCB11-mutated cohort from healthy controls and undiagnosed cholestasis patients (AUC=0.946, p < 0.0001) and, in non-ABCB11-mutated cholestasis patients, could distinguish BSEP dysfunction from normal BSEP function (9/12 vs 0/38, p < 0.0000001). CONCLUSIONS: Profiling of plasma bile acids has provided insights into cholestasis alleviation and may be useful for the clinical management of cholestatic diseases.


Assuntos
Membro 11 da Subfamília B de Transportadores de Cassetes de Ligação de ATP/genética , Ácidos e Sais Biliares/sangue , Colestase Intra-Hepática/sangue , Colestase Intra-Hepática/genética , Estudos de Casos e Controles , Pré-Escolar , China , Cromatografia Líquida de Alta Pressão , Feminino , Humanos , Lactente , Masculino , Mutação
18.
J Hepatol ; 66(5): 1001-1011, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28082148

RESUMO

BACKGROUND & AIMS: In the normal liver, hepatocytes form a uniquely polarised cell layer that enables movement of solutes from sinusoidal blood to canalicular bile. Whilst several cholestatic liver diseases with defects of hepatocyte polarity have been identified, the molecular mechanisms of pathogenesis are not well defined. One example is arthrogryposis, renal dysfunction and cholestasis syndrome, which in most patients is caused by VPS33B mutations. VPS33B is a protein involved in membrane trafficking that interacts with RAB11A at recycling endosomes. To understand the pathways that regulate hepatocyte polarity better, we investigated VPS33B deficiency using a novel mouse model with a liver-specific Vps33b deletion. METHODS: To assess functional polarity, plasma and bile samples were collected from Vps33b liver knockout (Vps33bfl/fl-AlfpCre) and control (Vps33bfl/fl) mice; bile components or injected substrates were quantitated by mass spectrometry or fluorometry. For structural analysis, livers underwent light and transmission electron microscopy. Apical membrane and tight junction protein localisation was assessed by immunostaining. Adeno-associated virus vectors were used for in vivo gene rescue experiments. RESULTS: Like patients, Vps33bfl/fl-AlfpCre mice showed mislocalisation of ATP-binding cassette proteins that are specifically trafficked to the apical membrane via Rab11a-positive recycling endosomes. This was associated with retention of bile components in blood. Loss of functional tight junction integrity and depletion of apical microvilli were seen in knockout animals. Gene transfer partially rescued these defects. CONCLUSIONS: Vps33b has a key role in establishing structural and functional aspects of hepatocyte polarity and may be a target for gene replacement therapy. LAY SUMMARY: Hepatocytes are liver cells with tops and bottoms; that is, they are polarised. At their bottoms they absorb substances from blood. They then, at their tops, secrete these substances and their metabolites into bile. When polarity is lost, this directional flow of substances from blood to bile is disrupted and liver disease follows. In this study, using a new mouse model with a liver-specific mutation of Vps33b, the mouse version of a gene that is mutated in most patients with arthrogryposis, renal dysfunction and cholestasis (ARC) syndrome, we investigated how the Vps33b gene product contributes to establishing hepatocyte polarity. We identified in these mice abnormalities similar to those in children with ARC syndrome. Gene transfer could partly reverse the mouse abnormalities. Our work contributes to the understanding of VPS33B disease and hepatocyte polarity in general, and may point towards gene transfer mediated treatment of ARC liver disease.


Assuntos
Polaridade Celular , Hepatócitos/fisiologia , Proteínas de Transporte Vesicular/fisiologia , Animais , Artrogripose/patologia , Artrogripose/terapia , Ácidos e Sais Biliares/sangue , Colestase/patologia , Colestase/terapia , Colesterol/sangue , Terapia Genética , Fígado/patologia , Camundongos , Camundongos Endogâmicos C57BL , Mutação , Insuficiência Renal/patologia , Insuficiência Renal/terapia , Junções Íntimas/fisiologia , Proteínas de Transporte Vesicular/genética
19.
Hepatology ; 63(2): 524-37, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26516723

RESUMO

UNLABELLED: Progressive familial intrahepatic cholestasis type 2 (PFIC-2) is caused by mutations in ABCB11, encoding the bile salt export pump (BSEP). In 2009, we described a child with PFIC-2 who developed PFIC-like symptoms after orthotopic liver transplantation (OLT). BSEP-reactive antibodies were demonstrated to account for disease recurrence. Here, we characterize the nature of this antibody response in 7 more patients with antibody-induced BSEP deficiency (AIBD). Gene sequencing and immunostaining of native liver biopsies indicated absent or strongly reduced BSEP expression in all 7 PFIC-2 patients who suffered from phenotypic disease recurrence post-OLT. Immunofluorescence, western blotting analysis, and transepithelial transport assays demonstrated immunoglobulin (Ig) G-class BSEP-reactive antibodies in these patients. In all cases, the N-terminal half of BSEP was recognized, with reaction against its first extracellular loop (ECL1) in six sera. In five, antibodies reactive against the C-terminal half also were found. Only the sera recognizing ECL1 showed inhibition of transepithelial taurocholate transport. In a vesicle-based functional assay, transport inhibition by anti-BSEP antibodies binding from the cytosolic side was functionally proven as well. Within 2 hours of perfusion with antibodies purified from 1 patient, rat liver showed canalicular IgG staining that was absent after perfusion with control IgG. CONCLUSIONS: PFIC-2 patients carrying severe BSEP mutations are at risk of developing BSEP antibodies post-OLT. The antibody response is polyclonal, targeting both extra- and intracellular BSEP domains. ECL1, a unique domain of BSEP, likely is a critical target involved in transport inhibition as demonstrated in several patients with AIBD manifest as cholestasis.


Assuntos
Transportadores de Cassetes de Ligação de ATP/deficiência , Transportadores de Cassetes de Ligação de ATP/imunologia , Anticorpos/sangue , Colestase Intra-Hepática/sangue , Colestase Intra-Hepática/imunologia , Complicações Pós-Operatórias/sangue , Complicações Pós-Operatórias/imunologia , Membro 11 da Subfamília B de Transportadores de Cassetes de Ligação de ATP , Adolescente , Criança , Colestase Intra-Hepática/genética , Feminino , Humanos , Transplante de Fígado , Masculino , Mutação , Complicações Pós-Operatórias/genética , Adulto Jovem
20.
BMC Gastroenterol ; 17(1): 77, 2017 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-28629372

RESUMO

BACKGROUND: Underlying causes in Chinese children with recurrent acute liver failure (RALF), including liver crises less than full acute liver failure, are incompletely understood. We sought to address this by searching for genes mutated in such children. METHODS: Five unrelated Chinese boys presenting between 2012 and 2015 with RALF of unexplained etiology were studied. Results of whole exome sequencing were screened for mutations in candidate genes. Mutations were verified in patients and their family members by Sanger sequencing. All 5 boys underwent liver biopsy. RESULTS: NBAS was the only candidate gene mutated in more than one patient (biallelic mutations, 3 of 5 patients; 5 separate mutations). All NBAS mutations were novel and predictedly pathogenic (frameshift insertion mutation c.6611_6612insCA, missense mutations c.2407G > A and c.3596G > A, nonsense mutation c.586C > T, and splicing-site mutation c.5389 + 1G > T). Of these mutations, 3 lay in distal (C-terminal) regions of NBAS, a novel distribution. Unlike the 2 patients without NBAS mutations, the 3 patients with confirmed NBAS mutations all suffered from a febrile illness before each episode of liver crisis (fever-related RALF), with markedly elevated alanine aminotransferase and aspartate aminotransferase activities 24-72 h after elevation of body temperature, succeeded by severe coagulopathy and mild to moderate jaundice. CONCLUSIONS: As in other countries, so too in China; NBAS disease is a major cause of fever-related RALF in children. The mutation spectrum of NBAS in Chinese children seems different from that described in other populations.


Assuntos
Povo Asiático/genética , Febre/genética , Falência Hepática Aguda/genética , Mutação , Proteínas de Neoplasias/genética , Criança , Pré-Escolar , China , Humanos , Lactente , Falência Hepática Aguda/complicações , Masculino , Recidiva , Estudos Retrospectivos
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