Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Methionine synthase reductase (MSR; gene name MTRR) is responsible for the reductive activation of methionine synthase. Cloning of the MTRR gene had revealed two major transcription start sites which, by alternative splicing, allows for two potential translation products of 698 and 725 amino acids. While the shorter protein was expected to target the cytosol where methionine synthase is located, the additional sequence in the longer protein was consistent with a role as a mitochondrial leader sequence. The possibility that MSR might target mitochondria was also suggested by the work of Leal et al. [N.A. Leal, H. Olteanu, R. Banerjee, T.A. Bobik, Human ATP:Cob(I)alamin adenosyltransferase and its interaction with methionine synthase reductase, J. Biol. Chem. 279 (2004) 47536-47542.] who showed that it can act as the reducing enzyme in combination with MMAB (ATP:Cob(I)alamin adenosyltransferase) to generate adenosylcobalamin from cob(II)alamin in vitro. Here we examined directly whether MSR protein is found in mitochondria. We show that, while two transcripts are produced by alternative splicing, the N-terminal segment of the putative mitochondrial form of MSR fused to GFP does not contain a sufficiently strong mitochondrial leader sequence to direct the fusion protein to the mitochondria of human fibroblasts. Further, antibodies to MSR protein localized MSR to the cytosol, but not to the mitochondria of human fibroblasts or the human hepatoma line Huh-1, as determined by Western blot analysis and immunofluorescence of cells in situ. These data confirm that MSR protein is restricted to the cytosol but, based on the Leal study, suggest that a similar protein may interact with MMAB to reduce the mitochondrial cobalamin substrate in the generation of adenosylcobalamin.
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PMID:Restricted role for methionine synthase reductase defined by subcellular localization. 1822 6

Hepatocellular carcinoma (HCC) is the third most frequent cause of cancer death in South Korea, but genetic susceptibility factors of HCC have not been examined extensively. Methylenetetrahydrofolate reductase (MTHFR) and methionine synthase reductase (MTRR) play an essential role in both DNA synthesis and methylation and polymorphisms in the MTHFR gene, 677C>T, 1298A>C and the MTRR gene, 66A>G, are associated with several types of malignancy. In this study, the allelic frequencies and genotype distribution of three polymorphisms in the MTHFR and MTRR genes from 96 hepatocellular carcinoma (HCC) patients and 201 controls were examined to assess the association between these polymorphisms and the development of HCC in this Korean population. The 66AG+GG (G allele-bearing) genotype of the MTRR gene was significantly associated with an increased risk of HCC (odds ratio, OR, 1.687; 95% confidence interval, CI=1.022-2.787). Moreover, the combination of MTHFR 1298AA/MTRR 66AG+GG (OR=1.854, 95% CI=1.005-3.420) and MTHFR 1298AC+CC/MTRR 66AG+GG (OR=2.733, 95% CI=1.195-6.249) showed a significant association with HCC risk. In the data classified by age and etiology, MTRR 66A>G over the age of 65 years, MTHFR 1298A>C under the age of 65 years and the MTRR 66AG+GG genotype in the hepatitis B virus (HBV) patients were increased risk factors for the disease. The MTHFR 1298A>C and the MTRR 66A>G genotypes were associated with an increased risk of HCC in this Korean population. Further studies involving larger and varied populations could provide a potential tool for cancer risk assessment in patients who are at risk of developing HCC.
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PMID:Methylenetetrahydrofolate reductase (MTHFR) and methionine synthase reductase (MTRR) gene polymorphisms as risk factors for hepatocellular carcinoma in a Korean population. 1903 14