Identification of a human 17p‐located cDNA encoding a protein of the Snf2‐like helicase family

Abstract

Following immunoscreening, we have cloned and sequenced a human cDNA encoding a novel member of the expanding helicase family. The deduced protein, designated hZFH (human zinc-finger helicase), contains the seven domains conserved among the helicase superfamily II and four potential zinc-fingers motifs. In particular, hZFH shows significant similarity to some proteins of the Snf2-like family, known to act as transcriptional regulators for multiples genes. Furthermore, hZFH has 68.5% identity to a human Mi-2 autoantigen to which autoantibodies are produced by a subgroup of patients affected by dermatomyositis. Northern-blot analyses have revealed several hZFH mRNAs with quantitative differences in various human tissues. One alternative splice site of hZFH mRNA was demonstrated and others were predicted. We also report the chromosomal localization of gene hZFH to locus 17p13-17p12 by in situ hybridization. Thus, this novel gene appears as a candidate for several malignant and genetic diseases associated with this region of the genome. The combination of these features suggests that hZFH plays an important role in gene regulation.Keywords : helicase ; human; cDNA; autoimmunity; chromosomal localization.Helicases constitute a large family of enzymes endowed with tional activation of a large set of inducible genes [7, 8]. These factors are believed to enhance transcription by assisting on ATPase activity and involved in double-stranded DNA and RNA unwinding. Numerous processes of nucleic acid metabolism, in-gene-specific activators in relieving repression, probably via an alteration of the chromatin structure [6, 9, 10]. cluding DNA replication, DNA repair, transcription, RNA splicing and translation require DNA and/or RNA helicases [1Ϫ3].Snf/Swi homologs have now been identified in Drosophila, mouse and human, suggesting a conserved role throughout euDespite the diversity of their physiological functions and the wide range of organisms in which they have been found, pro-karyotes in transcriptional activation. The human homolog, called hBRM, is 56% identical to brahma (also called brm), a nounced sequence conservation was maintained in helicase families. On the basis of different sequence signatures, the members regulator of homeotic genes in Drosophila [11], and 33% identical to yeast Snf2. hBRM was shown to be a strong activator of this protein family are subdivided into superfamilies I, II and III [4, 5]. Each protein of superfamilies I and II contains seven of transcription when tethered to DNA through fusion with a specific DNA-binding domain [12]. Moreover, hBRM (also highly conserved motifs (I, Ia, IIϪVI) termed helicase domains, clustered in a region of 200Ϫ700 amino acids. The similarity known as hSNF2A) and a strikingly related (75% identity) protein, BRG1 (also known as hSNF2β), can function as two tranin the structure and arrangement of these motifs suggests that superfamilies I and II have evolved from a common ances-scriptional coactivators cooperating with the estrogen, the glucocorticoid and the retin...

The Chromatin Remodeling Factor Mi-2α Acts as a Novel Co-activator for Human c-Myb

“…The expression plasmid for full-length FLAG-tagged Mi-2␣ (pCIneoB-3FLAG-Mi2␣) was made from three partial Mi-2␣ cDNA clones (hZFH clones 37-1 and 37-8 (25), covering the cDNA of Mi-2␣ from bp 945 to bp 6005, relative to ATG and a commercially bought construct pUC57-NTD-Mi-2␣ (GeneScript) covering the cDNA of Mi-2␣ from bp 1 to bp 974 relative to ATG) and the vector pCIneoB-3FLAG (unpublished construct; pCIneo from Promega). The mammalian expression plasmid for FLAG-tagged N-terminal domain (amino acid residues 1-315) of Mi-2␣ (pCIneoB-3FLAG-Mi2␣-NTD) was made by subcloning the region encoding the N-terminal Mi-2␣ (GeneScript) from pUC57-NTD-Mi-2␣ into pCIneoB-3FLAG.…”

“…AF006515), except for a 102-bp insert present in the C-terminal part of hZFH and a slightly extended C terminus. The clone we identified started in this 102-bp insert, which has been shown to be an optional exon (25). CHD3, also designated Mi-2␣, is reported to be one of two helicase subunits of the NuRD complex (19).…”

CHD8 Associates with Human Staf and Contributes to Efficient U6 RNA Polymerase III Transcription

“…The subfamily II CHD3 (Mi2a) and CHD4 (Mi2b) proteins are closely related and characterized by two PHD (plant homeodomain) zinc fingers (3,15) located N terminal of the double chromodomain. They are in complexes containing the histone deacetylases HDAC1/HDAC2 and referred to as the Mi2 (71), NuRD (nucleosome-remodeling histone deacetylase) (76,77), and NRD (nucleosome remodeling and deacetylating) (66) complexes.…”

Ki-1/57 Interacts with RACK1 and Is a Substrate for the Phosphorylation by Phorbol 12-Myristate 13-Acetate-activated Protein Kinase C

“…Our analysis resulted in the identification of the human protein chromo-helicase-DNA-binding domain protein 3 (CHD3) as a partner for both proteins (9). The CHD proteins are members of the chromo domain family, a class of proteins that are involved in transcriptional regulation and chromatin remodeling (11)(12)(13)(14)(15)(16)(17). The binding of the proteins Ki-1/57 and CGI-55 to CHD3 might define them as a family of CHD3-binding proteins and suggested the possibility that they could be involved in nuclear functions associated with the remodeling of chromatin and the regulation of transcription.…”