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Tomotsugu Yasuda,
Naoki Yamaguchi,
Keiko Kobayashi,
Ikumi Nishi,
Hidehito Horinouchi,
Md. Abdul Jalil,
Meng Xian Li,
Miharu Ushikai,
Mikio Iijima,
Ikuko Kondo,
Takeyori Saheki
[show abstract]
[hide abstract]
ABSTRACT: Adult-onset type II citrullinemia (CTLN2) is characterized by a liver-specific deficiency of argininosuccinate synthetase
(ASS) protein. We have recently identified the gene responsible for CTLN2, viz., SLC25A13, which encodes a calcium-binding
mitochondrial carrier protein, designated citrin, and found five mutations of the SLC25A13 gene in CTLN2 patients. In the
present study, we have identified two novel mutations, 1800ins1 and R605X, in SLC25A13 mRNA and the SLC25A13 gene. Diagnostic
analysis for the seven mutations in 103 CTLN2 patients diagnosed by biochemical and enzymatic studies has revealed that 102
patients had one or two of the seven mutations and 93 patients were homozygotes or compound heterozygotes. These results indicate
that CTLN2 is caused by an abnormality in the SLC25A13 gene, and that our criteria for CTLN2 before DNA diagnosis are correct.
Five of 22 patients from consanguineous unions have been shown to be compound heterozygotes, suggesting a high frequency of
the mutated genes. The frequency of homozygotes is calculated to be more than 1 in 20,000 from carrier detection (6 in 400
individuals tested) in the Japanese population. We have detected no cross-reactive immune materials in the liver of CTLN2
patients with any of the seven mutations by Western blot analysis with anti-human citrin antibody. From these findings, we
hypothesize that CTLN2 is caused by a complete deletion of citrin, although the mechanism of ASS deficiency is still unknown.
Human Genetics 04/2012; 107(6):537-545. · 5.07 Impact Factor
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Hong-Zhi Gao,
Keiko Kobayashi,
Ayako Tabata,
Hideaki Tsuge,
Mikio Iijima, Tomotsugu Yasuda,
H Serap Kalkanoglu,
Ali Dursun,
Aysegul Tokatli,
Turgay Coskun, [......],
Margarita Rodés,
Pornswan Wasant,
Ichiro Yoshida,
Linda De Meirleir,
Md Abdul Jalil,
Laila Begum,
Masahisa Horiuchi,
Nobuhiko Katunuma,
Shiro Nakagawa,
Takeyori Saheki
[show abstract]
[hide abstract]
ABSTRACT: Classical citrullinemia (CTLN1), a rare autosomal recessive disorder, is caused by mutations of the argininosuccinate synthetase (ASS) gene, localized on chromosome 9q34.1. ASS functions as a rate-limiting enzyme in the urea cycle. Previously, we identified 32 mutations in the ASS gene of CTLN1 patients mainly in Japan and the United States, and to date 34 different mutations have been described in 50 families worldwide. In the present study, we report ASS mutations detected in 35 additional CTLN1 families from 11 countries. By analyzing the entire coding sequence and the intron-exon boundaries of the ASS gene using RT-PCR and/or genomic DNA-PCR, we have identified 16 novel mutations (two different 1-bp deletions, a 67-bp insertion, and 13 missense) and have detected 12 known mutations. Altogether, 50 different mutations (seven deletion, three splice site, one duplication, two nonsense, and 37 missense) in 85 CTLN1 families were identified. On the basis of primary sequence comparisons with the crystal structure of E. coli ASS protein, it may be concluded that any of the 37 missense mutations found at 30 different positions led to structural and functional impairments of the human ASS protein. It has been found that three mutations are particularly frequent: IVS6-2A>G in 23 families (Japan: 20 and Korea: three), G390R in 18 families (Turkey: six, U.S.: five, Spain: three, Israel: one, Austria: one, Canada: one, and Bolivia: one), and R304W in 10 families (Japan: nine and Turkey: one). Most mutations of the ASS gene are "private" and are distributed throughout the gene, except for exons 5 and 12-14. It seems that the clinical course of the patients with truncated mutations or the G390R mutation is early-onset/severe. The phenotype of the patients with certain missense mutations (G362V or W179R) is more late-onset/mild. Eight patients with R86H, A118T, R265H, or K310R mutations were adult/late-onset and four of them showed severe symptoms during pregnancy or postpartum. However, it is still difficult to prove the genotype-phenotype correlation, because many patients were compound heterozygotes (with two different mutations), lived in different environments at the time of diagnosis, and/or had several treatment regimes or various knowledge of the disease.
Human Mutation 07/2003; 22(1):24-34. · 5.69 Impact Factor
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Milagros Ramos,
Araceli del Arco,
Beatriz Pardo,
Alberto Martínez-Serrano,
Juan Ramón Martínez-Morales,
Keiko Kobayashi, Tomotsugu Yasuda,
Elena Bogónez,
Paola Bovolenta,
Takeyori Saheki,
Jorgina Satrústegui
[show abstract]
[hide abstract]
ABSTRACT: Aralar1 and citrin are two isoforms of the mitochondrial carrier of aspartate-glutamate (AGC), a calcium regulated carrier, which is important in the malate-aspartate NADH shuttle. The expression and cell distribution of aralar1 and citrin in brain cells has been studied during development in vitro and in vivo. Aralar1 is the only isoform expressed in neurons and its levels undergo a marked increase during in vitro maturation, which is higher than the increase in mitochondrial DNA in the same time window. The enrichment in aralar1 per mitochondria during neuronal maturation is associated with a prominent rise in the function of the malate-aspartate NADH shuttle. Paradoxically, during in vivo development of rat or mouse brain there is very little postnatal increase in total aralar1 levels per mitochondria. This is explained by the fact that astrocytes develop postnatally, have aralar1 levels much lower than neurons, and their increase masks that of aralar1. Aralar1 mRNA and protein are widely expressed throughout neuron-rich areas in adult mouse CNS with clear enrichments in sets of neuronal nuclei in the brainstem and, particularly, in the ventral horn of the spinal cord. These aralar1-rich neurons represent a subset of the cytochrome oxidase-rich neurons in the same areas. The presence of aralar1 could reflect a tonic activity of these neurons, which is met by the combination of high malate-aspartate NADH shuttle and respiratory chain activities.
Developmental Brain Research 07/2003; 143(1):33-46. · 1.78 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Adult-onset type II citrullinemia (CTLN2), characterized by a liver-specific deficiency of urea cycle enzyme, argininosuccinate synthetase, is caused by mutations in SLC25A13 that encodes a calcium binding mitochondrial solute carrier protein, citrin. Citrin deficiency causes not only CTLN2 but also neonatal intrahepatic cholestasis caused by citrin deficiency at neonatal period. Moreover citrin and its isoform aralar were found to be aspartate glutamate carrier. From the viewpoint of the metabolic functions of citrin as aspartate glutamate carrier in urea synthesis and NADH shuttle, symptoms of CTLN2 and neonatal intrahepatic cholestasis caused by citrin deficiency are analyzed.
Metabolic Brain Disease 01/2003; 17(4):335-46. · 2.20 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: In an infant who suffered from prolonged icterus and hepatocellular dysfunction we detected an increase of citrulline and dibasic amino acids in plasma and urine. The amino acid levels along with all the abnormal liver tests normalized upon replacing breast-milk by formula feeding; there was no relapse after human milk was tentatively reintroduced. A novel mutation, a approximately 9.5-kb genomic duplication, was identified in the citrin gene (SLC25A13) resulting in the insertion of exon 15. No mutation was detected in the CAT2A specific exon of the SLC7A2 gene which encodes for the liver transporter of cationic amino acids. This is the first report of infantile citrin deficiency in non-Asian patients.
Molecular Genetics and Metabolism 12/2002; 77(3):202-8. · 3.19 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: The present report describes the expression profiles of different tissues and developmental changes of mouse aspartate/glutamate carrier (AGC) genes, Slc25a13 and Slc25a12, and an ornithine transporter gene, Ornt1, in relation to urea cycle enzyme genes, carbamoylphosphate synthetase I (CPS) and argininosuccinate synthetase (ASS). Slc25a13 encodes citrin, recently found to be deficient in adult-onset type II citrullinemia and to function as AGC together with its isoform and product of Slc25a12, aralar1. Citrin was broadly distributed, but mainly in the liver, kidney and heart. Aralar1 was expressed in diaphragm, skeletal muscle, heart, brain and kidney, but not in the liver. These distribution profiles are different from the restricted of Ornt1, ASS and CPS. Citrin, ASS, CPS and Ornt1 showed similar patterns of developmental changes in the liver and small intestine, where they play a role in urea and arginine synthesis. Dietary, hormonal and physical manipulations caused varied changes of CPS, ASS and Ornt1 in the liver, but the change of citrin was not so marked as that of the others. Analysis using RT-PCR and restriction enzyme digestion revealed that the ornithine transporter most expressed is Ornt1, although Ornt2 is detectable at a minute level. All these results suggest that citrin as AGC plays a role in urea synthesis as well as many fundamental metabolic pathways in the liver, and shares metabolic functions with aralar1 in other tissues, and that Ornt1 is an important component in urea synthesis in the liver and in arginine synthesis in the small intestine during the neonatal period.
Biochimica et Biophysica Acta 05/2002; 1574(3):283-92. · 4.66 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: We have recently identified SLC25A13 on chromosome 7q21.3 as the gene responsible for adult-onset type II citrullinemia (CTLN2) and found seven mutations in the SLC25A13 gene of CTLN2 patients. Most recently, the SLC25A13 mutations have been detected in neonatal/infantile patients with a type of neonatal hepatitis associated with cholestasis (NICCD). In the present study, we identified a novel mutation, E601X, in the SLC25A13 gene and established multiple DNA diagnosis methods for eight mutations by using a genetic analyzer with GeneScan and the single primer extension procedure (SNaPshot). An additional novel missense mutation (variation), E601K, was detected by SNaPshot analysis and was indistinguishable from the mutation E601X detected by the PCR/RFLP method. Multiple DNA diagnoses for the nine mutations revealed that 100 (male/female: 70/30) out of 115 CTLN2 and 38 (14/24) out of 45 NICCD patients tested were homozygotes or compound heterozygotes. The frequency of homozygotes carrying SLC25A13 mutations in both alleles is estimated to be minimally 1 in 21,000 from carrier detection (18 in 1,315 individuals tested) in the Japanese population. The differences in the gender ratio and in mutation types between CTLN2 and NICCD patients are significant. It is, however, unknown whether all homozygotes with mutated SLC25A13 in both alleles suffer from NICCD, CTLN2, both, or neither.
Human Mutation 03/2002; 19(2):122-30. · 5.69 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: We have previously reported that CDV (carnitine deficiency-associated gene expressed in ventricle)-1 was a down-regulated gene in the hypertrophied ventricle of carnitine-deficient juvenile visceral steatosis mice and that
the related gene (CDV-1R) showed no tissue specificity and no sensitivity to carnitine deficiency. In the present paper, the CDV-1/1R gene was isolated from a mouse genomic BAC library, and the genomic structure was characterized. We found that the CDV-1/1R gene consisted of at least 19 exons and encompassed approximately 48 kb. The splice sites conformed to the GT-AG rule, and
the CDV-1R mRNA containing 19 exons was processed. CDV-1 mRNA containing 5 exons was constructed from the 3′ half of CDV-1R.
The first exon of CDV-1 consisted of the 3′ side (116 bp) of intron 14 and exon 15 (87 bp) of CDV-1R. The presumed promoter
sequence for CDV-1 located in the intron 14 of CDV-1R contained the common TATA box and consensus binding sites for various
transcription factors (Nkx-2.5, Sp1, C/EBP, SRF, YY1, and CREB), which seem to play roles in the heart-specific expression
and carnitine deficiency-associated suppression of CDV-1. In the upstream region of the CDV-1 promoter, we found two VNTRs,
13 repeats of GATA1, and 16 copies of STRE involved in yeast stress response. The CDV-1/1R gene was located close to D5MIT68 on mouse Chromosome (Chr) 5, corresponding to human Chr 12q24. All these data revealed that two mRNA species, CDV-1 and CDV-1R,
are expressed tissue-specifically by using promoters peculiar to each transcript in a single gene.
Mammalian Genome 01/2000; 11(12):1053-1057. · 2.89 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Near-infrared spectroscopy (NIRS) is a cerebral monitoring method that noninvasively and continuously measures cerebral hemoglobin oxygenation and the redox state of cytochrome oxidase using highly tissue-permeable near-infrared light. This technique now has wide clinical application, and its usefulness in the measurement of cerebral hemoglobin oxygenation has been confirmed under global cerebral injury and/or hypoxemic hypoxia; however, regional cerebral infarction located far from the monitoring site may not be detected by NIRS. Furthermore, the specificity and accuracy of the measurement of the redox state of cytochrome oxidase remain controversial. We apply NIRS to both animal and clinical investigations. Based on these results, we discuss the significance of the measurement of cerebral hemoglobin oxygenation and cytochrome oxidase in vivo and in clinical medicine. Using our algorithm, cytochrome oxidase signals are unaffected by hemoglobin signals, even when hematocrit values change from 35 to 5% under cardiopulmonary bypass in a dog model. In the clinical study, cytochrome oxidase during surgery is likely to be a good (though not perfect) predictor of postoperative cerebral outcome. NIRS appears to be a promising technology, but additional investigations are required to establish its clinical efficacy and justify its routine use during operative and perioperative periods.
Journal of Biomedical Optics 13(3):033001. · 3.16 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: The present report describes the expression profiles of different tissues and developmental changes of mouse aspartate/glutamate carrier (AGC) genes, Slc25a13 and Slc25a12, and an ornithine transporter gene, Ornt1, in relation to urea cycle enzyme genes, carbamoylphosphate synthetase I (CPS) and argininosuccinate synthetase (ASS). Slc25a13 encodes citrin, recently found to be deficient in adult-onset type II citrullinemia and to function as AGC together with its isoform and product of Slc25a12, aralar1. Citrin was broadly distributed, but mainly in the liver, kidney and heart. Aralar1 was expressed in diaphragm, skeletal muscle, heart, brain and kidney, but not in the liver. These distribution profiles are different from the restricted of Ornt1, ASS and CPS. Citrin, ASS, CPS and Ornt1 showed similar patterns of developmental changes in the liver and small intestine, where they play a role in urea and arginine synthesis. Dietary, hormonal and physical manipulations caused varied changes of CPS, ASS and Ornt1 in the liver, but the change of citrin was not so marked as that of the others. Analysis using RT-PCR and restriction enzyme digestion revealed that the ornithine transporter most expressed is Ornt1, although Ornt2 is detectable at a minute level. All these results suggest that citrin as AGC plays a role in urea synthesis as well as many fundamental metabolic pathways in the liver, and shares metabolic functions with aralar1 in other tissues, and that Ornt1 is an important component in urea synthesis in the liver and in arginine synthesis in the small intestine during the neonatal period.
Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression.
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Milagros Ramos,
Araceli del Arco,
Beatriz Pardo,
Alberto Martı́nez-Serrano,
Juan Ramón Martı́nez-Morales,
Keiko Kobayashi, Tomotsugu Yasuda,
Elena Bogónez,
Paola Bovolenta,
Takeyori Saheki,
Jorgina Satrústegui
[show abstract]
[hide abstract]
ABSTRACT: Aralar1 and citrin are two isoforms of the mitochondrial carrier of aspartate–glutamate (AGC), a calcium regulated carrier, which is important in the malate–aspartate NADH shuttle. The expression and cell distribution of aralar1 and citrin in brain cells has been studied during development in vitro and in vivo. Aralar1 is the only isoform expressed in neurons and its levels undergo a marked increase during in vitro maturation, which is higher than the increase in mitochondrial DNA in the same time window. The enrichment in aralar1 per mitochondria during neuronal maturation is associated with a prominent rise in the function of the malate–aspartate NADH shuttle. Paradoxically, during in vivo development of rat or mouse brain there is very little postnatal increase in total aralar1 levels per mitochondria. This is explained by the fact that astrocytes develop postnatally, have aralar1 levels much lower than neurons, and their increase masks that of aralar1. Aralar1 mRNA and protein are widely expressed throughout neuron-rich areas in adult mouse CNS with clear enrichments in sets of neuronal nuclei in the brainstem and, particularly, in the ventral horn of the spinal cord. These aralar1-rich neurons represent a subset of the cytochrome oxidase-rich neurons in the same areas. The presence of aralar1 could reflect a tonic activity of these neurons, which is met by the combination of high malate–aspartate NADH shuttle and respiratory chain activities.
Developmental Brain Research.
