• Environmental Mutagens and Carcinogens
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• v.22 no.4
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• pp.236-242
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• 2002

Using agarose-coupled methotrexate, we have successfully isolated two proteins, which have strong interactions with methotrexate. The two proteins were analyzed by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry and identified as carbamoyl-phosphate synthetase 2 and phosphoribosylglycinamide formyltransferase, respectively. Interestingly, both of these two proteins are essential key enzymes in nucleotide biosynthetic pathways, like dihydrofolate reductase, a well-known methotrexate target. We confirmed the specificity of their interactions between methotrexate and two target proteins by the methods of competition binding assay, which were followed by western blotting using antibody against carbamoyl-phosphate synthetase 2 and phosphoribosylglycinamide formyltransferase, respectively. Moreover, we could observe that carbamoyl-phosphate synthetase 2 is overexpressed in methotrexate-resistant MOLT-3 cells comparing with control MOLT-3 cells. This result indicates that carbamoyl-phosphate synthetase 2 may be a novel target of methotrexate in cancer therapy. We propose that chemical proteomics can be a powerful technique to identify target proteins of a chemical.

• YAKHAK HOEJI
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• v.51 no.3
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• pp.214-218
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• 2007

In the previous reports, we developed the CO5 by introducing genes for the first and second urea cycle enzymes, carbamoyl phosphate synthetase I (CPS I) and ornithine transcarbamoylase (OTC) into the IBE cell lines producing erythropoietin (EPO). The CO5 have been found out to have 15-20% higher cell growth rate and produce 2-times more EPO than the parental cell line, IBE. To investigate the role of CPS I in CO5 cell line for the cell growth and amount of EPO, we knock-downed CPS I gene expression via siRNA treatment. Expression level of EPO in cell lysate of CO5 was 3-5 fold higher than that of IBE. After siRNA treatment, the cell growth of CO5 was decreased 8-21% and the EPO productivity in the cell Iysate was significantly decreased. However, these changes of the cell growth and EPO productivity were not observed in IBE. These results indicate that CPS I gene expression is important for the increased cell growth and EPO productivity of CO5 cell line.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.16 no.2
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• pp.109-114
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• 2016

Carbamoyl phosphate synthetase 1 (CPS1) deficiency is an autosomal recessive urea cycle disorder which causes hyperammonemia. CPS1 is the first enzyme step in the urea cycle and almost patients present their symptoms during neonatal period. We report a case of CPS1 deficiency in a boy who developed symptoms including lethargy and seizure at 3 days of age. The ammonia level was up to $2,325{\mu}mol/L$, sodium benzoate (250 mg/kg/d) and high calories of both dextrose and lipid was promptly administered. Central access by experienced pediatric surgeon and emergent continuous hemodialysis by pediatric nephrologist was performed within 3 hours and ammonia was less than $100{\mu}mol/L$ at 5 days of age. Currently, he has showed excellent response to treatments including scavenging drugs and a low-protein diet. Despite of diffuse increasing signal intensity on cerebral white matters and basal ganglia on brain MRI, his development and weight gain were good at the last follow-up at 11 months of age. Molecular assay of the CPS1 gene demonstrated that patient had compound heterozygous for c.1529del ($p.Gly510Alafs^*5$) in exon 14 and c.3142-1G>C (IVS25(-1)G>C) in intron 25 and exon 26 boundary. The splicing mutation was novel mutation and inherited from patient's mother. Here, we report a neonatal lethal type CPS1 deficiency patient having novel mutation.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.18 no.1
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• pp.23-29
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• 2018

Carbamoyl phosphate synthetase 1 deficiency (CPS1D) is a rare autosomal recessive urea cycle disorder characterized by hyperammonemia. CPS1D is caused by mutations in the CPS1 gene on chromosome 2q35. Based on the age of onset, there are two phenotypes: the neonatal type and the delayed-onset type. The severity of clinical manifestation depends on the degree of CPS1 residual enzymatic activity, and can result in hyperammonemia and neurological dysfunction. We report a case of CPS1D in a neonate who developed vomiting, decreased consciousness and hyperammonemia at 25th day after birth. She showed excellent response to treatment including hydration, ammonia-lowering drugs and a low-protein diet without hemodialysis. Her growth, development and neurological outcomes were fair at the last follow-up at 17 months of age.

• Journal of Microbiology and Biotechnology
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• v.14 no.4
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• pp.844-851
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• 2004

Efficient mammalian erythropoietin (EPO)-expression systems are required for therapeutic applications. The accumulation of ammonia is a major problem in the production of recombinant proteins in cultured animal cells. To counter this problem we introduced the first two genes of the urea cycle, carbamoyl phosphate synthetase (CPSI) and ornithine transcarbamylase (OTC), into IBE Chinese Hamster Ovary (CHO) cells by stable transfection. The resulting cell line, CO5, had a higher growth rate and accumulated less ammonia per cell than the parental cell line, IBE. In addition, it produced 2 times more EPO than the parent, and the purified EPO contained a higher proportion of acidic isoforms with approximately 15% more sialic acid.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.17 no.1
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• pp.31-37
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• 2017

Carbamoyl phosphate synthetase 1 deficiency (CPS1D) is an autosomal recessive disorder of the urea cycle that causes hyperammonemia. Two forms of CPS1D are recognized: a lethal neonatal type and a less severe, delayed-onset type. Neonatal CPS1D cases often present their symptoms within the first days of life. Delayed-onset cases are predominantly adolescents or adults, and infantile delayed-onset cases are rare. Severe hyperammonemia in the neonatal period leads to serious brain damage, coma, and death if not treated promptly. Therefore, early diagnosis and acute treatment are crucial. Despite the improvement of treatments, including continuous hemodialysis, ammonia-lowering agents, and a low-protein diet, the overall outcome of severe forms of hyperammonemia often remains disappointing. As the liver is the only organ in which ammonia is converted into urea, liver transplantation has been considered as an elegant and radical alternative therapy to classical dietary and medical therapies. However, liver transplantation has many disadvantages, such as a considerable risk for technical complications and perioperative metabolic derangement, especially in neonates. Additionally, there is a lack of suitable donor organs in most countries. According to recent studies, liver cell transplantation is a therapeutic option and serves as a bridge to liver transplantation. Here, we report a Korean CPS1D patient with novel mutations in CPS1 who was treated by liver cell transplantation after being diagnosed in the neonatal period and showed a good neurodevelopmental outcome at the last follow-up at six months of age.

• Archives of Pharmacal Research
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• v.28 no.2
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• pp.220-226
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• 2005

Temperature and medium composition were changed with the aim of increasing growth and erythropoietin (EPO) production in EPO-producing Chinese hamster ovary (CHO) cells. We used the CHO cell line, IBE, and its derivative, CO5, which over-expresses the first two enzymes of the urea cycle, carbamoyl phosphate synthetase I (CPS I) and ornithine transcar-bamoylase (OTC). When supplements were added to the medium at $33\;^{\circ}C$, the growth of IBE and CO5 cells increased by $27\%\;and;26\%$, respectively and the maximum yield of EPO was increased by $40\%$ in both cell lines. The absolute EPO concentration in the CO5 cells was always $55{\sim}60\%$ higher than in the IBE cells. In addition, when the two cell lines were continuously cultured with supplements at $33\;^{\circ}C$ until their growth rates approached those at $37\;^{\circ}C$, the growth rates of both IBE and CO5 cells increased by $54\%$ and their maximum EPO levels increased by up to $73\%\;and\;56\%$, respectively. Therefore, the growth and EPO expression levels of CO5 cells increased 2.2-fold and 2.6-fold, respectively, compared to those of the IBE cells. These results indicate that adaptation to lower temperature as well as medium supplementation could be important for improving cell growth and EPO production.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.21 no.1
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• pp.15-21
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• 2021

Purpose: Urea cycle disorder (UCD) is an inherited inborn error of metabolism, acting on each step of urea cycle that cause various phenotypes. The purpose of the study was to investigate the long-term clinical consequences in different groups of UCD to characterize it. Methods: Twenty-two patients with UCD genetically confirmed were enrolled at Pusan National University Children's hospital and reviewed clinical features, biochemical and genetic features retrospectively. Results: UCD diagnosed in the present study included ornithine transcarbamylase deficiency (OTCD) (n=10, 45.5%), argininosuccinate synthase 1 deficiency (ASSD) (n=6, 27.3%), carbamoyl-phosphate synthetase 1 deficiency (CPS1D) (n=3, 13.6%), hyperornithinemia-hyperammonemia-homocitrullinuria syndrome (HHHS) (n=2, 9.1%), and arginase-1 deficiency (ARG1D) (n=1, 4.5%). The age at the diagnosis was 32.7±66.2 months old (range 0.1 to 228.0 months). Eight (36.4%) patients with UCD displayed short stature. Neurologic sequelae were observed in eleven (50%) patients with UCD. Molecular analysis identified 37 different mutation types (14 missense, 6 nonsense, 6 deletion, 6 splicing, 3 delins, 1 insertion, and 1 duplication) including 14 novel variants. Progressive growth impairment and poor neurological outcomes were associated with plasma isoleucine and leucine concentrations, respectively. Conclusion: Although combinations of treatments such as nutritional restriction of proteins and use of alternative pathways for discarding excessive nitrogen are extensively employed, the prognosis of UCD remains unsatisfactory. Prospective clinical trials are necessary to evaluate whether supplementation with BCAAs might improve growth or neurological outcomes and decrease metabolic crisis episodes in patients with UCD.