Journal of Biological Chemistry
Volume 276, Issue 34, 24 August 2001, Pages 32300-32312
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GENES: STRUCTURE AND REGULATION
Characterization of Two Evolutionarily Conserved, Alternatively Spliced Nuclear Phosphoproteins, NFAR-1 and -2, That Function in mRNA Processing and Interact with the Double-stranded RNA-dependent Protein Kinase, PKR*

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We report here the isolation and characterization of two proteins, NFAR-1 and -2, which were isolated through their ability to interact with the dsRNA-dependent protein kinase, PKR. The NFAR proteins, of 90 and 110 kDa, are derived from a single gene through alternative splicing and are evolutionarily conserved nuclear phosphoproteins that interact with double-stranded RNA. Both NFAR-1 and -2 are phosphorylated by PKR, reciprocally co-immunoprecipitate with PKR, and colocalize with the kinase in a diffuse nuclear pattern within the cell. Transfection studies indicate that the NFARs regulate gene expression at the level of transcription, probably during the processing of pre-mRNAs, an activity that was increased in fibroblasts lacking PKR. Subsequent functional analyses indicated that amino acids important for NFAR's activity were localized to the C terminus of the protein, a region that was found to specifically interact with FUS and SMN, proteins also known as regulators of RNA processing. Accordingly, both NFARs were found to associate with both pre-mRNAs and spliced mRNAs in post-transcriptional studies, similar to the known splicing factor ASF/SF-2. Collectively, our data indicate that the NFARs may facilitate double-stranded RNA-regulated gene expression at the level of post-transcription and possibly contribute to host defense-related mechanisms in the cell.

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Published, JBC Papers in Press, July 3, 2001, DOI 10.1074/jbc.M104207200

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The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) AF320227– (human NFAR gene) and and (NFAR-1 and -2 cDNA nucleotide and amino acid sequences, respectively) (41).

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Supported by funds awarded from the Lucille P. Markey Trust and American Cancer Society Instututional Research Grant 1RG-98-277-04.