Genetic polymorphisms of aldehyde dehydrogenase 2, cytochrome p450 2E1 for liver cancer risk in HCV antibody-positive japanese patients and the variations of CYP2E1 mRNA expression levels in the liver due to its polymorphism.

BACKGROUND: Hepatocellular carcinoma (HCC) in persons with liver cirrhosis (LC) arises following hepatitis virus infection. Alcohol may accelerate the risk of development of LC and HCC. Cytochrome p450 2E1 (CYP2E1) oxidizes ethanol to form acetaldehyde and aldehyde dehydrogenase 2 (ALDH2) detoxifies acetaldehyde, which is carcinogenic in humans, and both alcohol-metabolizing enzymes show the genetic polymorphisms in a Japanese population. METHODS: Using polymorphism analysis, we studied the frequency of ALDH2 functional deletion due to the G to A single-bp mutation in exon 12 and CYP2E1 polymorphism in the transcriptional region, both associated with higher levels of acetaldehyde, in 135 patients with LC and/or HCC, including 99 with HCC, and 135 non-cancer controls. The mRNA expression levels of CYP2E1 in the liver were also examined in 55 surgical specimens. RESULTS: The allelic frequency of the homozygous ALDH2 2-2 genotype, coding for the enzyme deletion, was significantly higher compared to that of the homozygous or heterozygous ALDH2 1-1 genotypes in cases with HCC (OR = 5.4, 95% CI 2.1-14.0). There were no differences in the frequencies of specific genotypes of CYP2E1 in cases of HCC, but combined analysis of ALDH2 and CYP2E1 revealed that the odds ratio of occurrence of the C1/C1 homozygosity of CYP2E1 and the ALDH2 2-2 homozygosity was as high as 23.0 (2.9-182). The mRNA levels of CYP2E1 were higher in the liver of patients with the C1/C1 homozygosity of CYP2E1 than in those with other genotypes (P < 0.05). CONCLUSIONS: ALDH2 and CYP2E1 polymorphisms may modify the risk of development of HCC against the background of LC in the Japanese. Polymorphism analysis of alcohol-metabolizing enzymes using molecular techniques may be useful in the risk assessment of liver cancer in patients with hepatitis C virus infection.

Genomic structure and transcriptional regulation of the early B cell gene chB1.

The avian B cell differentiation Ag chB1 is a membrane glycoprotein relative of the mammalian B cell differentiation Ag CD72. Unlike CD72, this C-type lectin is expressed in relatively high levels on immature B cells in the bursa of Fabricius and is down-regulated on mature B cells in the periphery. An immunoreceptor tyrosine-based inhibitory motif in the chB1 cytoplasmic tail suggests a potential regulatory role in intrabursal B cell development. To gain further insight into the selective expression and function of chB1, we determined the genomic organization of chB1 and examined the mechanism of its transcriptional regulation. The 8-exon chB1 gene proved to have very similar organization to that of mouse CD72, further supporting the idea that chB1 is a CD72 relative. As for mouse CD72, the chB1 promoter region lacks a TATA box but contains a conserved initiator element. The 131-bp region (-161 to -30) proximal to the transcriptional start site, which contains a potential early B cell factor binding site, is essential for the B lineage stage-specific transcription of chB1, whereas PU.1 and B cell-specific activator protein/Pax5 have been shown to play important roles in CD72 promoter activity and cell-type specificity. This analysis suggests that differences in transcriptional regulation of these phylogenetically related genes may determine the differences in expression pattern and, therefore, the function of avian chB1 and mammalian CD72 during B cell development.

BASH, a novel signaling molecule preferentially expressed in B cells of the bursa of Fabricius.

The bursa of Fabricius is a gut-associated lymphoid organ that is essential for the generation of a diversified B cell repertoire in the chicken. We describe here a novel gene preferentially expressed in bursal B cells. The gene encodes an 85-kDa protein, designated BASH (B cell adaptor containing SH2 domain), that contains N-terminal acidic domains with SH2 domain-binding phosphotyrosine-based motifs, a proline-rich domain, and a C-terminal SH2 domain. BASH shows a substantial sequence similarity to SLP-76, an adaptor protein functioning in TCR-signal transduction. BASH becomes tyrosine-phosphorylated with the B cell Ag receptor (BCR) cross-link or by coexpression with Syk and Lyn and associates with signaling molecules including Syk and a putative chicken Shc homologue. Overexpression of BASH results in suppression of the NF-AT activation induced by BCR-cross-linking. These findings suggest that BASH is involved in BCR-mediated signal transduction and could play a critical role in B cell development in the bursa.

Takaokamycin, a new peptide antibiotic produced by Streptomyces sp.

A new peptide antibiotic named takaokamycin was isolated from a fermentation broth of Streptomyces sp. AC-1978, a soil isolate. It exhibits antibacterial activity against some Gram-positive bacteria. The molecular weight was found to be 1,130 on the basis of elemental analysis, FD-mass spectrum and 1H and 13C NMR. Acid hydrolysate of takaokamycin contains isoleucine, threonine and unidentified amino acids.

Effect of ammonium ion, inorganic phosphate and amino acids on the biosynthesis of protylonolide, a precursor of tylosin aglycone.

The production of tylosin by Streptomyces fradiae KA-427 in a defined medium was inhibited by ammonium ions and by inorganic phosphate. The production of protylonolide, an early lactonic intermediate of tylosin biosynthesis with the same carbon skeleton as tylosin aglycone, by a mutant of strain KA-427 was also reduced by these two kinds of ions. In contrast, the bioconversion of protylonolide to tylosin by another mutant was less susceptible to ammonium ions but was sensitive to inorganic phosphate. The addition of protylonolide to a culture of S. fradiae KA-427 increased the tylosin yield, suggesting that aglycone synthesis is limiting under the conditions used. When L-valine, L-leucine, L-isoleucine, L-threonine, or the corresponding 2-keto acid was added to the culture medium, the protylonolide titer increased. The addition of [14C]valine gave rise to [14C]protylonolide. 13C NMR spectroscopic analysis revealed that iso-butyrate, which is a valine metabolite, was incorporated into protylonolide at the carbons known to originate from propionate and n-butyrate. Taking account of these findings, the regulation of tylosin biosynthesis in S. fradiae by ammonium ion is discussed in relation to amino acid metabolism.