Multiple Functions of Nuclear DNA Helicase II (RNA Helicase A) in Nucleic Acid Metabolism

Abstract Nuclear DNA helicase II (NDH II), or RNA helicase A (RHA), was initially discovered in mammals by conventional protein purification methods. Molecular cloning identified apparent sequence homologies between NDH II and a Drosophila protein named maleless (MLE), the latter being essential for the Drosophila X-chromosome dosage compensation. Increasing amounts of evidence suggest that NDH II is involved in multiple aspects of cellular and viral DNA and RNA metabolism. Moreover the functions of NDH II may have potential clinical implications related to viral infection, autoimmune diseases, or even tumorigenesis.

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DNA-dependent protein kinase (DNA-PK) phosphorylates nuclear DNA helicase II/RNA helicase A and hnRNP proteins in an RNA-dependent manner

Nucleic Acids Research ◽

10.1093/nar/gkg933 ◽

2004 ◽

Vol 32 (1) ◽

pp. 1-10 ◽

Cited By ~ 80

Author(s):

S. Zhang

Keyword(s):

Protein Kinase ◽

Nuclear Dna ◽

Rna Helicase ◽

Dna Helicase ◽

Dependent Manner ◽

Dependent Protein Kinase ◽

Rna Helicase A ◽

Dna Helicase Ii ◽

Hnrnp Proteins ◽

Dependent Protein

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Nuclear DNA Helicase II (RNA Helicase A) Interacts with Werner Syndrome Helicase and Stimulates Its Exonuclease Activity

Journal of Biological Chemistry ◽

10.1074/jbc.m503882200 ◽

2005 ◽

Vol 280 (35) ◽

pp. 31303-31313 ◽

Cited By ~ 28

Author(s):

Jana Friedemann ◽

Frank Grosse ◽

Suisheng Zhang

Keyword(s):

Nuclear Dna ◽

Werner Syndrome ◽

Rna Helicase ◽

Dna Helicase ◽

Exonuclease Activity ◽

Rna Helicase A ◽

Dna Helicase Ii

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Molecular Cloning of the Gene Encoding Nuclear DNA Helicase II. A BOVINE HOMOLOGUE OF HUMAN RNA HELICASE A ANDDROSOPHILAMle PROTEIN

Journal of Biological Chemistry ◽

10.1074/jbc.270.27.16422 ◽

1995 ◽

Vol 270 (27) ◽

pp. 16422-16427 ◽

Cited By ~ 34

Author(s):

Suisheng Zhang ◽

Heiko Maacke ◽

Frank Grosse

Keyword(s):

Molecular Cloning ◽

Nuclear Dna ◽

Rna Helicase ◽

Dna Helicase ◽

Rna Helicase A ◽

Gene Encoding ◽

Dna Helicase Ii

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Domain Structure of Human Nuclear DNA Helicase II (RNA Helicase A)

Journal of Biological Chemistry ◽

10.1074/jbc.272.17.11487 ◽

1997 ◽

Vol 272 (17) ◽

pp. 11487-11494 ◽

Cited By ~ 75

Author(s):

Suisheng Zhang ◽

Frank Grosse

Keyword(s):

Domain Structure ◽

Nuclear Dna ◽

Rna Helicase ◽

Dna Helicase ◽

Rna Helicase A ◽

Dna Helicase Ii

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Pre-mRNA and mRNA binding of human nuclear DNA helicase II (RNA helicase A)

Journal of Cell Science ◽

10.1242/jcs.112.7.1055 ◽

1999 ◽

Vol 112 (7) ◽

pp. 1055-1064

Author(s):

S. Zhang ◽

C. Herrmann ◽

F. Grosse

Keyword(s):

Nuclear Dna ◽

Binding Protein ◽

Rna Helicase ◽

Dna Helicase ◽

Hnrnp A1 ◽

Rna Helicase A ◽

Dna Helicase Ii ◽

Transcriptional Inhibition ◽

Mrna Binding Protein ◽

Mrna Binding

Nuclear DNA helicase II (NDH II), alternatively named RNA helicase A, seems to function as a pre-mRNA and mRNA binding protein in human cells. Immunofluorescence studies of NDH II gave a highly diffused nucleoplasmic staining that was similar to that of hnRNP A1 but differed from the localization of the RNA splicing factor Sc-35. Upon transcriptional inhibition, NDH II migrated from the nucleus into the cytoplasm. During mitosis, NDH II was released into the cytoplasm during pro- to metaphase, and was gradually recruited back into telophase nuclei. The timing of nuclear import of NDH II at telophase was found to be later than that of hnRNP A1 but paralleled that of Sc-35. At the ultrastructural level, both NDH II and hnRNP A1 were identified within perichromatin ribonucleoparticle fibrils. However, the subnuclear distributions of NDH II and hnRNP A1 were not overlapping. NDH II could be extracted together with poly(A)-containing mRNA from HeLa cell nuclei and, to a much lesser extent, from the cytoplasm. Following transcriptional inhibition, NDH II was preferentially associated with mRNA from the cytosol, which biochemically confirmed the microscopic observations. Although NDH II is mainly a nuclear enzyme, it is apparently not associated with the nuclear matrix, since it could be extracted with 2 M NaCl from DNase I-treated nuclei. Our cellular and biochemical observations strongly suggest that NDH II is a pre-mRNA and mRNA binding protein. Its significant affinity for ssDNA, but not for dsDNA, points to a transient role in DNA binding during the process of transcript formation. According to our model, single-stranded DNA might be necessary to retain NDH II in the nuclear compartment.

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