Coupling of dephosphorylation and nuclear export of Smads in TGF-beta signaling

Methods Mol Biol. 2010:647:125-37. doi: 10.1007/978-1-60761-738-9_7.

Abstract

In eukaryotes, regulation of signaling mediators/effectors in the nucleus is one of the principal mechanisms that govern duration and strength of signaling. Smads are a family of structurally related intracellular proteins that serve as signaling effectors for transforming growth factor beta (TGF-beta) and TGF-beta-related proteins. Accumulating evidence demonstrates that Smads possess intrinsic nucleocytoplasmic shuttling capacity, which enables them to transmit TGF-beta signals from cell membrane to nucleus. We recently identified two important steps in the termination of nuclear Smad signaling. The first step is initiated by a serine/threonine phosphatase PPM1A that dephosphorylates Smad2/3 in the nucleus, thereby shutting down signaling capacity of phosphorylated Smad2/3. The second step involves nuclear export of dephosphorylated Smad2/3 with the aid of nuclear protein RanBP3 to terminate Smad signaling. This chapter introduces methods for examining nuclear export of Smad2/3 in TGF-beta signaling.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus
  • Cell Fractionation
  • Cell Line
  • Cell Nucleus / metabolism*
  • Humans
  • Intracellular Space / metabolism
  • Phosphoric Monoester Hydrolases / metabolism
  • Phosphorylation
  • Signal Transduction*
  • Smad Proteins / metabolism*
  • Transforming Growth Factor beta / metabolism*

Substances

  • Smad Proteins
  • Transforming Growth Factor beta
  • Phosphoric Monoester Hydrolases