North American Indian Childhood Cirrhosis Research Articles

Early predictors of unfavourable outcome in progressive cholestasis of northwestern Quebec.

Progressive cholestasis of northwestern Quebec (PCNQ) is a rare and severe form of cirrhosis affecting children from Quebec's First Nations. First described by our group in 1981 and historically named North American Indian childhood cirrhosis, such a condition often requires liver transplantation during the pediatric age. This study aimed at suggesting a more culturally sensitive name for the disease and identifying early prognostic factors for an unfavourable outcome. We retrospectively collected data of all 14 consecutive patients diagnosed with PCNQ over the last 20 years and compared children listed for liver transplant before 18 years of age (LT, n = 7) to those with milder disease progression (no-LT, n = 7). Compared with the no-LT group, LT children developed serious complications with an unusually high incidence of gastrointestinal bleeding. Over the first 12 months from presentation, a greater increase of alanine aminotransferase plasma levels, decrease of total bilirubin, and increase of alanine aminotransferase-to-total bilirubin ratio was observed in the LT group. Bone mineral density was lower in LT children independently of vitamin D levels. Patients with PCNQ showed poorer bone health than age-matched children with other cholestatic disorders. In the name of cultural sensitivity, PCNQ should be the preferred name for this condition. Variation of alanine aminotransferase and total bilirubin plasma levels over the first 12 months from presentation might be used for the early identification of children with PCNQ who are at higher risk of unfavourable outcomes. This might help optimize clinical management to populations that are underserved by health care services.

Quantum Language of MicroRNA: Application for New Cancer Therapeutic Targets.

MicroRNA (miRNA) is the noncoding gene: therefore, the miRNA gene inheritably controls protein gene expression through transcriptional and post-transcriptional levels. Aberrant expression of miRNA genes causes various human diseases, especially cancers. Although cancer is a complex disease, cancer/miRNA implication has yet been grasped from the perspective of miRNA profile in bed side. Since miRNA is the mobile genetic element, the clinical verification of miRNAin microvesicle of blood is too much straggle to predict potential cancer/miRNA associations without bioinformatical computing. Further, experimental investigation of miRNA/cancer pathways is expensive and time-consuming. While the accumulated data (big data) of miRNA profiles has been on line as the databases in cancers, using the database algorithms for miRNA target prediction have reduced required time for conventional experiments and have cut the cost. Computational prediction of miRNA/target mRNA has shown numerous significant outcomes that are unobtainable only by experimental approaches. However, ID of miRNA in the annotation is an arbitrary number and the ID is not related with miRNA its functions. Therefore, it has not been physicochemically shown why multiple miRNAs in blood or tissues are useful for diagnosis and porgnosis of human diseases or why function of single miRNA in cancer is rendered to oncomir or tumopr suppressor. In addition, it is less cleared why environmental factors, such as temperature, radiation, therapeutic anti-cancer immune or chemical agents can alter the expression of miRNAs in the cell. The ceRNA theory would not be enough for the investigation of such subjects. Given miRNA/target prediction tools, to elucidate such issues with computer simulationwe have previously introduced the quantum miRNA/miRNA interaction as a new scoring using big database. The quantum score was implicated in miRNA synergisms in cancer and participated in the miRNA/target interaction on human diseases. On the other hand, ribosomal RNA (rRNA) is the dominant RNA species of the cells. It is well known that ribosomopathies, such as Diamond-Blackfan anemia, dyskeratiosis congenital, Shwachman-Diamond syndrome, 5q-myelodysplastic syndrome, Treacher Collins syndrome, cartilage-hair hypoplasia, North American Indian childhood cirrhosis, isolated congenital asplenia, Bowen-Conradi syndrome and cancer are caused by altered expression of ribosomal proteins or rRNA genes. We haveproposed the hypothesis thatthe interaction among miRNAs from rRNA and/or other cellular miRNAs would be involved into cancer as the ribosomopathy. Subsequently, we found rRNA-derived miRNAs (rmiRNAs) by using the sequence homology search(miPS) with miRNA database(miRBase). Further, the pathwayrelated with cancer between rmiRNA/target protein gene was predicted by miRNA entangling target sorting (METS) algorithm. In this chapter, we describe about the usage of in silico miRNA identification program, miRNA/target prediction search through the database and quantum language of miRNAby the METS, and the ontology analysis. In particular, the METS algorithm according to the quantum value would be useful simulator to discover a new therapeutic target aganist cancer. It mayalso partly contribute to the elucidation of complex mechanisms and development of agents of anti-cancer.

Human diseases of the SSU processome

Ribosomes are the cellular machines responsible for protein synthesis. Ribosome biogenesis, the production of ribosomes, is a complex process involving pre-ribosomal RNA (rRNA) cleavages and modifications as well as ribosomal protein assembly around the rRNAs to create the functional ribosome. The small subunit (SSU) processome is a large ribonucleoprotein (RNP) in eukaryotes required for the assembly of the SSU of the ribosome as well as for the maturation of the 18S rRNA. Despite the fundamental nature of the SSU processome to the survival of any eukaryotic cell, mutations in SSU processome components have been implicated in human diseases. Three SSU processome components and their related human diseases will be explored in this review: hUTP4/Cirhin, implicated in North American Indian childhood cirrhosis (NAIC); UTP14, implicated in infertility, ovarian cancer, and scleroderma; and EMG1, implicated in Bowen–Conradi syndrome (BCS). Diseases with suggestive, though inconclusive, evidence for the involvement of the SSU processome in their pathogenesis are also discussed, including a novel putative ribosomopathy. This article is part of a Special Issue entitled: Role of the Nucleolus in Human Disease.

P53-Mediated Biliary Defects Caused by Knockdown of cirh1a, the Zebrafish Homolog of the Gene Responsible for North American Indian Childhood Cirrhosis

North American Indian Childhood Cirrhosis (NAIC) is a rare, autosomal recessive, progressive cholestatic disease of infancy affecting the Cree-Ojibway first Nations of Quebec. All NAIC patients are homozygous for a missense mutation (R565W) in CIRH1A, the human homolog of the yeast nucleolar protein Utp4. Utp4 is part of the t-Utp subcomplex of the small subunit (SSU) processome, a ribonucleoprotein complex required for ribosomal RNA processing and small subunit assembly. NAIC has thus been proposed to be a primary ribosomal disorder (ribosomopathy); however, investigation of the pathophysiologic mechanism of this disease has been hindered by lack of an animal model. Here, using a morpholino oligonucleotide (MO)-based loss-of-function strategy, we have generated a model of NAIC in the zebrafish, Danio rerio. Zebrafish Cirhin shows substantial homology to the human homolog, and cirh1a mRNA is expressed in developing hepatocytes and biliary epithelial cells. Injection of two independent MOs directed against cirh1a at the one-cell stage causes defects in canalicular and biliary morphology in 5 dpf larvae. In addition, 5 dpf Cirhin-deficient larvae have dose-dependent defects in hepatobiliary function, as assayed by the metabolism of an ingested fluorescent lipid reporter. Previous yeast and in vitro studies have shown that defects in ribosome biogenesis cause stabilization and nuclear accumulation of p53, which in turn causes p53-mediated cell cycle arrest and/or apoptosis. Thus, the nucleolus appears to function as a cellular stress sensor in some cell types. In accordance with this hypothesis, transcriptional targets of p53 are upregulated in Cirhin-deficient zebrafish embryos, and defects in biliary function seen in Cirhin-deficient larvae are completely abrogated by mutation of tp53. Our data provide the first in vivo evidence of a role for Cirhin in biliary development, and support the hypothesis that congenital defects affecting ribosome biogenesis can activate a cellular stress response mediated by p53.

NOL11, implicated in the pathogenesis of North American Indian Childhood Cirrhosis, is required for pre‐rRNA transcription and processing

The R565W mutation in the C‐terminus of the nucleolar ribosome biogenesis factor, hUTP4/Cirhin, causes North American Indian childhood cirrhosis (NAIC). Our objective was to identify non‐conserved interaction partners for hUTP4/Cirhin, as a defective protein‐protein interaction may underlie NAIC. By screening a yeast two‐hybrid cDNA library derived from human liver, and through affinity purification followed by mass spectrometry, we identified an uncharacterized nucleolar protein, NOL11, as an interaction partner for hUTP4/Cirhin. Co‐immunoprecipitation experiments show that NOL11 is a component of the nucleolar human ribosomal small subunit (SSU) processome. siRNA knockdown of NOL11 revealed that it is required to generate the mature 18S rRNA and for optimal rDNA transcription. Yeast two‐hybrid analysis shows that NOL11 interacts with the C‐terminus of hUTP4/Cirhin, and that the R565W mutation partially disrupts this interaction. Expression of the hUTP4/Cirhin R565W mutation only partially rescues the ribosome biogenesis defects, indicating that the disease mutation confers a defect in ribosome biogenesis. We have therefore identified NOL11 as a novel protein required for the nucleolar stages of ribosome biogenesis in humans. Our results further implicate a role for NOL11 in the pathogenesis of NAIC. Supported by NIH GM52581.

NOL11, Implicated in the Pathogenesis of North American Indian Childhood Cirrhosis, Is Required for Pre-rRNA Transcription and Processing

The fundamental process of ribosome biogenesis requires hundreds of factors and takes place in the nucleolus. This process has been most thoroughly characterized in baker's yeast and is generally well conserved from yeast to humans. However, some of the required proteins in yeast are not found in humans, raising the possibility that they have been replaced by functional analogs. Our objective was to identify non-conserved interaction partners for the human ribosome biogenesis factor, hUTP4/Cirhin, since the R565W mutation in the C-terminus of hUTP4/Cirhin was reported to cause North American Indian childhood cirrhosis (NAIC). By screening a yeast two-hybrid cDNA library derived from human liver, and through affinity purification followed by mass spectrometry, we identified an uncharacterized nucleolar protein, NOL11, as an interaction partner for hUTP4/Cirhin. Bioinformatic analysis revealed that NOL11 is conserved throughout metazoans and their immediate ancestors but is not found in any other phylogenetic groups. Co-immunoprecipitation experiments show that NOL11 is a component of the human ribosomal small subunit (SSU) processome. siRNA knockdown of NOL11 revealed that it is involved in the cleavage steps required to generate the mature 18S rRNA and is required for optimal rDNA transcription. Furthermore, abnormal nucleolar morphology results from the absence of NOL11. Finally, yeast two-hybrid analysis shows that NOL11 interacts with the C-terminus of hUTP4/Cirhin and that the R565W mutation partially disrupts this interaction. We have therefore identified NOL11 as a novel protein required for the early stages of ribosome biogenesis in humans. Our results further implicate a role for NOL11 in the pathogenesis of NAIC.

The C-terminus of Utp4, mutated in childhood cirrhosis, is essential for ribosome biogenesis

The small subunit (SSU) processome is a large ribonucleoprotein that is required for maturation of the 18S rRNA of the ribosome. Recently, a missense mutation in the C-terminus of an SSU processome protein, Utp4/Cirhin, was reported to cause North American Indian childhood cirrhosis (NAIC). In this study, we use Saccharomyces cerevisiae as a model to investigate the role of the NAIC mutation in ribosome biogenesis. While we find that the homologous NAIC mutation does not cause growth defects or aberrant ribosome biogenesis in yeast, we show that an intact C-terminus of Utp4 is required for cell growth and maturation of the 18S and 25S rRNAs. A protein–protein interaction map of the seven-protein t-Utp subcomplex of which Utp4 is a member shows that Utp8 interacts with the C-terminus of Utp4 and that this interaction is essential for assembly of the SSU processome and for the function of Utp4 in ribosome biogenesis. Furthermore, these results allow us to propose that NAIC may be caused by dysfunctional pre-ribosome assembly due to the loss of an interaction between the C-terminus of Utp4/Cirhin and another SSU processome protein.

Cirhin up-regulates a canonical NF-κB element through strong interaction with Cirip/HIVEP1

North American Indian childhood cirrhosis ( NAIC/CIRH1A) is a severe autosomal recessive intrahepatic cholestasis. All NAIC patients have a homozygous mutation in CIRH1A that changes conserved Arg565 to Trp (R565W) in Cirhin, a nucleolar protein of unknown function. Subcellular localization is unaffected by the mutation. Yeast two-hybrid screening identified Cirip (Cirhin interaction protein) and found that interaction between Cirip and R565W-Cirhin was weakened. Co-immunoprecipitation of the two proteins from nuclear extracts of HeLa cells strongly supports the yeast two hybrid results. Cirip has essentially the same sequence as the C-terminal of HIVEP1, a regulator of a canonical NF-κB sequence. Since Cirip has the zinc fingers required for this interaction, we developed an in vitro assay based on this element in mammalian cells to demonstrate functional Cirhin–Cirip interaction. The strong positive effect of Cirip on the NF-κB sequence was further increased by both Cirhin and R565W-Cirhin. Importantly, the effect of R565W-Cirhin was weaker than that of the wild type protein. We observed increased levels of Cirhin–Cirip complex in nuclear extracts in the presence of this NF-κB sequence. Our hypothesis is that Cirhin is a transcriptional regulatory factor of this NF-κB sequence and could be a participant in the regulation of other genes with NF-κB responsive elements. Since the activities of genes regulated through NF-κB responsive elements are especially important during development, this interaction may be a key to explain the perinatal appearance of NAIC.

La cirrhose amérindienne infantile

North American Indian childhood cirrhosis is a distinct form of neonatal familial cholestasis. To date, it has only been described in aboriginal children from northwestern Quebec. The disease rapidly evolves into cirrhosis with early portal hypertension and bleeding from esophageal varices. Twelve of 36 children followed at l'Hôpital Ste-Justine since 1970 received a liver transplant. As of now, there are 17 living NAIC patients, 6 of whom had liver transplantation. We mapped NAIC to chromosome 16q22, and identified mutations in CIRH1A in patients. All are homozygous for the R565W mutation in cirhin, a WD40 repeat protein of unknown function. We showed that cirhin is a resident in the nucleolus. Cirhin interacts with Cirip, a functional, alternative splice variant of the HIVEP1 protein. Their interaction indicates synergistic action. The complete inactivation of mouse homolog, tex292 is likely embryonic lethal. The continued collaboration between patients, their families, clinicians and researchers that has helped to identify the disease gene and to develop a diagnostic test now focuses on finding a new treatment for this unique disease affecting First Nations children from Québec.

Nucleolar localization of cirhin, the protein mutated in North American Indian childhood cirrhosis

Cirhin (NP_116219), the product of the CIRH1A gene is mutated in North American Indian childhood cirrhosis (NAIC/CIRH1A, OMIM 604901), a severe autosomal recessive intrahepatic cholestasis. It is a 686-amino-acid WD40-repeat containing protein of unknown function that is predicted to contain multiple targeting signals, including an N-terminal mitochondrial targeting signal, a C-terminal monopartite nuclear localization signal (NLS) and a bipartite nuclear localization signal (BNLS). We performed the direct determination of subcellular localization of cirhin as a crucial first step in unraveling its biological function. Using EGFP and His-tagged cirhin fusion proteins expressed in HeLa and HepG2, cells we show that cirhin is a nucleolar protein and that the R565W mutation, for which all NAIC patients are homozygous, has no effect on subcellular localization. Cirhin has an active C-terminal monopartite nuclear localization signal (NLS) and a unique nucleolar localization signal (NrLS) between residues 315 and 432. The nucleolus is not known to be important specifically for intrahepatic cholestasis. These observations provide a new dimension in the study of hereditary cholestasis.

Population history and its impact on medical genetics in Quebec

Knowledge of the genetic demography of Quebec is useful for gene mapping, diagnosis, treatment, community genetics and public health. The French-Canadian population of Quebec, currently about 6 million people, descends from about 8500 French settlers who arrived in Nouvelle-France between 1608 and 1759. The migrations of those settlers and their descendants led to a series of regional founder effects, reflected in the geographical distribution of genetic diseases in Quebec. This review describes elements of population history and clinical genetics pertinent to the treatment of French Canadians and other population groups from Quebec and summarizes the cardinal features of over 30 conditions reported in French Canadians. Some were discovered in French Canadians, such as autosomal recessive ataxia of the Charlevoix-Saguenay (MIM 270550), agenesis of corpus callosum and peripheral neuropathy (MIM 218000) and French-Canadian-type Leigh syndrome (MIM 220111). Other conditions are particularly frequent or have special genetic characteristics in French Canadians, including oculopharyngeal muscular dystrophy, hepatorenal tyrosinaemia, cystic fibrosis, Leber hereditary optic neuropathy and familial hypercholesterolaemia. Three genetic diseases of Quebec First Nations children are also discussed: Cree encephalitis (MIM 608505), Cree leukoencephalopathy (MIM 603896) and North American Indian childhood cirrhosis (MIM 604901).

Ascites after orthotopic liver transplantation in children

Ascites is a poorly understood postoperative complication of orthotopic liver transplantation (OLT). It is associated with additional morbidity and can prolong hospitalization considerably. The incidence, the factors predictive of occurrence and the etiology of this complication are not known. The charts of 118 patients with 138 OLT were analyzed according to the following criteria: ascites lasting longer than the first 10 postoperative days, assessed by loss of ascitic fluid through drainage tubes, surgical wounds or paracentesis, with a peak volume of > or =10 mL/kg/day. Patients were divided into three groups: Group 1, no ascites; Group 2, ascites associated with postoperative complications, including chylus ascites; and Group 3, ascites not associated with postoperative complications. Postoperative ascites occurred in 43 of 138 OLT (31.2%). Patients with biliary atresia, preoperative portal hypertension, postoperative pleural effusion or at retransplantation had ascites significantly more often. In 32 of 138 (23.2%) OLT, ascites was associated with postoperative complications, including thrombosis, abdominal infections, intestinal perforation, biliary leak, pancreatitis, and chylus ascites. In 11 of 138 (7.9%) OLT, ascites was the only postoperative complication (group 3). Group three patients were significantly older, and had lower preoperative platelet counts and preoperative ascites more often than group 1 patients. The primary liver diseases were mainly cystic fibrosis of the pancreas, congenital hepatic fibrosis, and North American Indian childhood cirrhosis. The serum-ascites albumin gradient suggested a hepatic origin of ascites. Postoperative ascites is associated with the duration and degree of preoperative portal hypertension. We speculate that the mechanism involved includes a disproportion between venous blood volume and liver uptake capacity of the donor organ.

Molecular basis of intrahepatic cholestasis

Intrahepatic cholestasis, or impairment of bile flow, is an important manifestation of inherited and acquired liver disease. In recent years, human genetic and molecular studies have identified several genes, the disruption of which results in cholestasis. ATP8B1 (FIC1), ABCB11 (BSEP), and ABCB4 (MDR3) are disrupted in forms of progressive familial intrahepatic cholestasis (PFIC) and related disorders. Mutations in BAAT, TJP2 (ZO‐2), and EPHX1 have been identified in patients with hypercholanemia. A CLDN1 mutation was recently reported in patients with ichthyosis, leukocyte vacuoles, alopecia and sclerosing cholangitis (ILVASC), and North American Indian childhood cirrhosis (NAIC) is associated with a missense mutation in CIRH1A. Alagille syndrome patients carry mutations in JAG1, and mutations in VPS33B have been identified in patients with arthrogryposis, renal dysfunction and cholestasis syndrome (ARC). Identification of these genes, and characterization of the proteins they encode, is enhancing our understanding of the biology of the enterohepatic circulation in health and disease.

A Missense Mutation (R565W) in Cirhin (FLJ14728) in North American Indian Childhood Cirrhosis

North American Indian childhood cirrhosis (CIRH1A, or NAIC), a severe autosomal recessive intrahepatic cholestasis described in Ojibway-Cree children from northwestern Quebec, is one of several familial cholestases with unknown molecular etiology. It typically presents with transient neonatal jaundice, in a child who is otherwise healthy, and progresses to biliary cirrhosis and portal hypertension. Clinical and physiological investigations have not revealed the underlying cause of the disease. Currently, liver transplantation is the only effective therapy for patients with advanced disease. We previously identified the NAIC locus by homozygosity mapping to chromosome 16q22. Here we report that an exon 15 mutation in gene FLJ14728 (alias Cirhin) causes NAIC: c.1741C-->T in GenBank cDNA sequence NM_032830, found in all NAIC chromosomes, changes the conserved arginine 565 codon to a tryptophan, altering the predicted secondary structure of the protein. Cirhin is preferentially expressed in embryonic liver, is predicted to localize to mitochondria, and contains WD repeats, which are structural motifs frequently associated with molecular scaffolds.

Localization of a Recessive Gene for North American Indian Childhood Cirrhosis to Chromosome Region 16q22—and Identification of a Shared Haplotype

North American Indian childhood cirrhosis (NAIC, or CIRH1A) is an isolated nonsyndromic form of familial cholestasis reported in Ojibway-Cree children and young adults in northwestern Quebec. The pattern of transmission is consistent with an autosomal recessive mode of inheritance. To map the NAIC locus, we performed a genomewide scan on three DNA pools of samples from 13 patients, 16 unaffected siblings, and 22 parents from five families. Analysis of 333 highly polymorphic markers revealed 3 markers with apparent excess allele sharing among affected individuals. Additional mapping identified a chromosome 16q segment shared by all affected individuals. When the program FASTLINK/LINKAGE was used and a completely penetrant autosomal recessive mode of inheritance was assumed, a maximum LOD score of 4.44 was observed for a recombination fraction of 0, with marker D16S3067. A five-marker haplotype (D16S3067, D16S752, D16S2624, D16S3025, and D16S3106) spanning 4.9 cM was shared by all patients. These results provide significant evidence of linkage for a candidate gene on chromosome 16q22.