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Start Over Author "Lin, Ya" Journal journal of biological chemistry
13 results on '"Lin, Ya"'

10. The Eukaryotic DNMT2 Genes Encode a New Class of Cytosine-5 DNA Methyltransferases

Author

Lin Ya Tang, M. Narsa Reddy, Ming Shiu Hung, Vanya Rasheva, Meng Jau Lin, Tai-Lin Lee, and C. K.James Shen

Subjects
DNA, Complementary, Insecta, Methyltransferase, Genetic Linkage, Blotting, Western, Molecular Sequence Data, Biology, Transfection, Polymerase Chain Reaction, Biochemistry, Genome, DNA methyltransferase, Cell Line, Animals, Genetically Modified, chemistry.chemical_compound, Sequence Homology, Nucleic Acid, Complementary DNA, Animals, Drosophila Proteins, Sulfites, Gene family, DNA (Cytosine-5-)-Methyltransferases, Molecular Biology, Gene, Genetics, Base Sequence, Models, Genetic, fungi, DNA, Cell Biology, DNA Methylation, Physical Chromosome Mapping, Phenotype, chemistry, DNMT1, Drosophila, Plasmids
Abstract

DNMT2 is a subgroup of the eukaryotic cytosine-5 DNA methyltransferase gene family. Unlike the other family members, proteins encoded by DNMT2 genes were not known before to possess DNA methyltransferase activities. Most recently, we have shown that the genome of Drosophila S2 cells stably expressing an exogenous Drosophila dDNMT2 cDNA became anomalously methylated at the 5'-positions of cytosines (Reddy, M. N., Tang, L. Y., Lee, T. L., and Shen, C.-K. J. (2003) Oncogene, in press). We present evidence here that the genomes of transgenic flies overexpressing the dDnmt2 protein also became hypermethylated at specific regions. Furthermore, transient transfection studies in combination with sodium bisulfite sequencing demonstrated that dDnmt2 as well as its mouse ortholog, mDnmt2, are capable of methylating a cotransfected plasmid DNA. These data provide solid evidence that the fly and mouse DNMT2 gene products are genuine cytosine-5 DNA methyltransferases.

Published
2003
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11. DNA Methyltransferase Gene dDnmt2 and Longevity of Drosophila.

Author

Meng-Jau Lin, Lin-Ya Tang, Reddy, M. Narsa, and Shen, C.-K. James

Subjects
*METHYLTRANSFERASES, *DROSOPHILA, *NUCLEIC acids, *DNA, *GENES, *METHYLATION
Abstract

The DNA methylation program of the fruit fly Drosophila melanogaster is carried out by the single DNA methyltransferase gene dDnmt2, the function of which is unknown before. We present evidence that intactness of the gene is required for maintenance of the normal life span of the fruit flies. In contrast, overexpression of dDnmt2 could extend Drosophila life span. The study links the Drosophila DNA methylation program with the small heatshock proteins and longevity/aging and has interesting implication on the eukaryotic DNA methylation programs in general. [ABSTRACT FROM AUTHOR]

Published
2005
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12. N-Glycosylation and Residues Asn805and Asn890Are Involved in the Functional Properties of Type VI Adenylyl Cyclase*

Author

Wu, Gour-Cheng, Lai, Hsing-Lin, Lin, Ya-Wen, Chu, Yin-Ting, and Chern, Yijuang

Abstract

In this study, we demonstrate that type VI adenylyl cyclase (ACVI) is glycosylated in vivo. Treating HEK293 cells expressing ACVI with tunicamycin to block the addition ofN-linked oligosaccharide or removing theN-linked oligosaccharide by in vitropeptidyl-N-glycosidase F digestion reduced the molecular mass of ACVI. Furthermore, tunicamycin treatment suppressed the forskolin-stimulated activity of ACVI. Mutation of either one or both potential N-glycosylation sites (Asn805and Asn890, located on extracellular loops 5 and 6, respectively) also reduced the molecular mass of ACVI. Therefore, ACVI was glycosylated at both Asn805and Asn890. Confocal analysis indicated that glycosylation was not required for the delivery of ACVI to the cell surface. Although no significant alterations in Kmvalues for ATP or sensitivity to divalent cations were detected, the glycosylation-deficient ACVI mutant N805Q/N890Q-ACVI exhibited much lower forskolin-, Mn2+-, and Mg2+-stimulated cyclase activities than did wild-type ACVI. By contrast, the Gαs-stimulated cyclase activities of wild-type ACVI and N805Q/N890Q-ACVI were indistinguishable. Furthermore, compared with wild-type ACVI, N805Q/N890Q-ACVI was less sensitive to inhibition mediated by dopamine D2 receptors or by protein kinase C. Collectively, glycosylation of ACVI not only affected its catalytic activity in an activator-dependent manner, but also altered its ability to be regulated by a Gαiprotein-coupled receptor or by protein kinase C.

Published
2001
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13. Purification and characterization of an endotoxin-binding protein with protease inhibitory activity from Limulus amebocytes.

Author

Minetti CA, Lin YA, Cislo T, and Liu TY

Subjects
Amino Acid Sequence, Animals, Base Sequence, Binding, Competitive, Cell Degranulation, Cloning, Molecular, DNA genetics, Disulfides, Horseshoe Crabs cytology, Microscopy, Electron, Molecular Sequence Data, Polymerase Chain Reaction, Polymyxin B metabolism, Trypsin Inhibitors chemistry, Endotoxins metabolism, Horseshoe Crabs enzymology, Lipopolysaccharides metabolism, Trypsin Inhibitors isolation & purification
Abstract

Using a lipopolysaccharide affinity column and ion exchange chromatography, a 12-kDa protein has been purified from Limulus amebocytes. In solid phase binding assays, the radiolabeled protein binds specifically to lipopolysaccharide (LPS) with a Kd value on the order of 10(-7) M. A cDNA coding for this protein has been isolated and sequenced. The amino acid sequence deduced from the cDNA indicates that this protein shares no sequence homology with LPS-binding proteins isolated from different species of vertebrates (Schumann, R. R., Leong, S. R., Flaggs, G. W., Gray, P. W., Wright, S. D., Mathison, J. C., Tobias, P. S., and Ulevitch, R. J. (1990) Science 249, 1429-1431) and invertebrates (Aketagawa, J., Miyata, T., Ohtsubo, S., Nakamura, T., Morita, T., Hayashida, H., Miyata, T., Iwanaga, S., Takao, T., and Shimonishi, Y. (1986) J. Biol. Chem. 261, 7357-7365). The binding to LPS can be displaced by the unlabeled 12-kDa protein, polymyxin B, lipid A, and to a lesser extent by D-glucosamine. In whole cell binding assays, the 12-kDa protein has also been shown to bind to Escherichia coli. Using both [14C]casein and a synthetic substrate, the protein has been shown to inhibit the proteolytic activity of trypsin, with an IC50 of approximately 10(-7) M. In the presence of LPS, the antitryptic acitivity of the Limulus endotoxin-binding protein-protease inhibitor remains unaffected. The protein is a major component of the cytoplasmic proteins (1%). Immunocytochemical analysis reveals that this protein exists in the secretory granules of the amebocytes where enzymes and substrates for the clotting cascade reside. Based on the unusual dual functional properties, the newly isolated protein was named a "Limulus endotoxin-binding protein-protease inhibitor" (LEBP-PI).

Published
1991

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