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

J Biol Chem. 2001 Aug 24;276(34):32300-12. doi: 10.1074/jbc.M104207200. Epub 2001 Jul 3.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alternative Splicing*
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • COS Cells
  • Cell Nucleus / metabolism
  • DNA Primers
  • DNA, Complementary
  • Evolution, Molecular*
  • Molecular Sequence Data
  • Nuclear Factor 90 Proteins
  • Phosphoproteins*
  • Precipitin Tests
  • Protein Isoforms / chemistry
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism*
  • Protein Isoforms / physiology
  • RNA Processing, Post-Transcriptional / physiology*
  • RNA, Messenger / metabolism*
  • RNA-Binding Proteins / chemistry
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*
  • RNA-Binding Proteins / physiology
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sequence Homology, Amino Acid
  • Substrate Specificity
  • eIF-2 Kinase / metabolism*

Substances

  • DNA Primers
  • DNA, Complementary
  • ILF3 protein, human
  • Nuclear Factor 90 Proteins
  • Phosphoproteins
  • Protein Isoforms
  • RNA, Messenger
  • RNA-Binding Proteins
  • eIF-2 Kinase

Associated data

  • GENBANK/AF167569
  • GENBANK/AF167570
  • GENBANK/AF320227
  • GENBANK/AF320228
  • GENBANK/AF320229
  • GENBANK/AF320230
  • GENBANK/AF320231
  • GENBANK/AF320232
  • GENBANK/AF320233
  • GENBANK/AF320234
  • GENBANK/AF320235
  • GENBANK/AF320236
  • GENBANK/AF320237
  • GENBANK/AF320238
  • GENBANK/AF320239
  • GENBANK/AF320240
  • GENBANK/AF320241
  • GENBANK/AF320242
  • GENBANK/AF320243
  • GENBANK/AF320244
  • GENBANK/AF320245
  • GENBANK/AF320246
  • GENBANK/AF320247