Enhancer of rudimentary homologue interacts with scaffold attachment factor B at the nuclear matrix to regulate SR protein phosphorylation

FEBS J. 2017 Aug;284(15):2482-2500. doi: 10.1111/febs.14141. Epub 2017 Jul 8.

Abstract

Scaffold attachment factor B1 (SAFB1) is an integral component of the nuclear matrix of vertebrate cells. It binds to DNA on scaffold/matrix attachment region elements, as well as to RNA and a multitude of different proteins, affecting basic cellular activities such as transcription, splicing and DNA damage repair. In the present study, we show that enhancer of rudimentary homologue (ERH) is a new molecular partner of SAFB1 and its 70% homologous paralogue, scaffold attachment factor B2 (SAFB2). ERH interacts directly in the nucleus with the C-terminal Arg-Gly-rich region of SAFB1/2 and co-localizes with it in the insoluble nuclear fraction. ERH, a small ubiquitous protein with striking homology among species and a unique structure, has also been implicated in fundamental cellular mechanisms. Our functional analyses suggest that the SAFB/ERH interaction does not affect SAFB1/2 function in transcription (e.g. as oestrogen receptor α co-repressors), although it reverses the inhibition exerted by SAFB1/2 on the splicing kinase SR protein kinase 1 (SRPK1), which also binds on the C-terminus of SAFB1/2. Accordingly, ERH silencing decreases lamin B receptor and SR protein phosphorylation, which are major SRPK1 substrates, further substantiating the role of SAFB1 and SAFB2 in the co-ordination of nuclear function.

Keywords: ERH; SAFB; SR protein; SRPK1; nuclear matrix.

MeSH terms

  • Active Transport, Cell Nucleus
  • Animals
  • Cell Cycle Proteins / antagonists & inhibitors
  • Cell Cycle Proteins / chemistry
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Cell Line, Tumor
  • Genes, Reporter
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • HEK293 Cells
  • Humans
  • Matrix Attachment Region Binding Proteins / chemistry
  • Matrix Attachment Region Binding Proteins / genetics
  • Matrix Attachment Region Binding Proteins / metabolism*
  • Microscopy, Fluorescence
  • Nuclear Matrix-Associated Proteins / chemistry
  • Nuclear Matrix-Associated Proteins / genetics
  • Nuclear Matrix-Associated Proteins / metabolism*
  • Peptide Fragments / chemistry
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism
  • Phosphorylation
  • Protein Interaction Domains and Motifs
  • Protein Multimerization
  • Protein Processing, Post-Translational*
  • Protein Serine-Threonine Kinases / antagonists & inhibitors
  • Protein Serine-Threonine Kinases / chemistry
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism*
  • RNA Interference
  • Rats
  • Receptors, Estrogen / chemistry
  • Receptors, Estrogen / genetics
  • Receptors, Estrogen / metabolism*
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / metabolism
  • Serine-Arginine Splicing Factors / chemistry
  • Serine-Arginine Splicing Factors / metabolism*
  • Transcription Factors / antagonists & inhibitors
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Two-Hybrid System Techniques

Substances

  • Cell Cycle Proteins
  • ERH protein, human
  • Matrix Attachment Region Binding Proteins
  • Nuclear Matrix-Associated Proteins
  • Peptide Fragments
  • Receptors, Estrogen
  • Recombinant Fusion Proteins
  • SAFB protein, human
  • SAFB2 protein, human
  • Transcription Factors
  • Green Fluorescent Proteins
  • Serine-Arginine Splicing Factors
  • SRPK1 protein, human
  • Protein Serine-Threonine Kinases