AF6/s-afadin is a dual residency protein and localizes to a novel subnuclear compartment

J Cell Physiol. 2007 Jan;210(1):212-23. doi: 10.1002/jcp.20853.

Abstract

The AF6/afadin protein is a component of cell membranes at specialized sites of cell-cell contact. Two main splice variants exist, known as l- and s-afadin, respectively. L-afadin is widely expressed in cells of epithelial origin, whilst s-afadin expression is restricted to the brain. Here we demonstrate that the short form of AF6/s-afadin is a dual residency protein able to localize to the plasma membrane or nucleus whilst the long form of AF6, l-afadin is unable to localize to the nucleus. AF6/s-afadin clusters in a distinctive speckled pattern in the nucleus, but is unable to do so when cell cycle progression is inhibited at the G(1)/S or G(2)/M checkpoints. The formation of AF6/s-afadin nuclear bodies is also sensitive to the transcriptional activity of the cell with inhibition of RNA polymerase activity abolishing AF6/s-afadin nuclear clustering. AF6/s-afadin nuclear bodies localize to a novel subnuclear compartment, failing to colocalize with other known nuclear bodies. Formation of the AF6/s-afadin nuclear foci can be regulated by specific growth factor receptor mediated signaling events and by cytoplasmic tyrosine kinases, but does not correlate with tyrosine phosphorylation of AF6/s-afadin. AF6/s-afadin is a candidate for mediating control of cellular growth processes by regulated translocation to the nucleus.

MeSH terms

  • Alternative Splicing
  • Animals
  • Cell Cycle / drug effects
  • Cell Line
  • Cell Membrane / metabolism*
  • Cell Nucleus / metabolism*
  • Cell Nucleus Structures / metabolism
  • DNA-Directed RNA Polymerases / antagonists & inhibitors
  • Dogs
  • Green Fluorescent Proteins / genetics
  • Humans
  • Kinesin / genetics
  • Kinesin / metabolism*
  • LIM Domain Proteins
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism*
  • Mitosis Modulators / pharmacology
  • Myosins / genetics
  • Myosins / metabolism*
  • Nucleic Acid Synthesis Inhibitors / pharmacology
  • Oligopeptides
  • Peptides / genetics
  • Phosphorylation
  • Protein Transport / drug effects
  • Protein-Tyrosine Kinases / genetics
  • Protein-Tyrosine Kinases / metabolism
  • Rats
  • Recombinant Proteins / metabolism
  • Signal Transduction
  • Time Factors
  • Transcription, Genetic / drug effects
  • Transfection

Substances

  • AFDN protein, human
  • Afdn protein, rat
  • LIM Domain Proteins
  • Microfilament Proteins
  • Mitosis Modulators
  • Nucleic Acid Synthesis Inhibitors
  • Oligopeptides
  • Peptides
  • Recombinant Proteins
  • afadin
  • Green Fluorescent Proteins
  • FLAG peptide
  • Protein-Tyrosine Kinases
  • DNA-Directed RNA Polymerases
  • Myosins
  • Kinesin