Non-Smad signaling pathways

Cell Tissue Res. 2012 Jan;347(1):11-20. doi: 10.1007/s00441-011-1201-y. Epub 2011 Jun 24.

Abstract

Transforming growth factor-beta (TGFβ) is a key regulator of cell fate during embryogenesis and has also emerged as a potent driver of the epithelial-mesenchymal transition during tumor progression. TGFβ signals are transduced by transmembrane type I and type II serine/threonine kinase receptors (TβRI and TβRII, respectively). The activated TβR complex phosphorylates Smad2 and Smad3, converting them into transcriptional regulators that complex with Smad4. TGFβ also uses non-Smad signaling pathways such as the p38 and Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) pathways to convey its signals. Ubiquitin ligase tumor necrosis factor (TNF)-receptor-associated factor 6 (TRAF6) and TGFβ-associated kinase 1 (TAK1) have recently been shown to be crucial for the activation of the p38 and JNK MAPK pathways. Other TGFβ-induced non-Smad signaling pathways include the phosphoinositide 3-kinase-Akt-mTOR pathway, the small GTPases Rho, Rac, and Cdc42, and the Ras-Erk-MAPK pathway. Signals induced by TGFβ are tightly regulated and specified by post-translational modifications of the signaling components, since they dictate the subcellular localization, activity, and duration of the signal. In this review, we discuss recent findings in the field of TGFβ-induced responses by non-Smad signaling pathways.

Publication types

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

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism
  • Epithelial-Mesenchymal Transition / physiology
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • GTP Phosphohydrolases / metabolism
  • Integrins / metabolism
  • MAP Kinase Kinase Kinases / metabolism
  • Receptors, Transforming Growth Factor beta / metabolism
  • Signal Transduction / physiology*
  • Smad Proteins / metabolism*
  • TNF Receptor-Associated Factor 6 / metabolism
  • Transforming Growth Factor beta / metabolism

Substances

  • Adaptor Proteins, Signal Transducing
  • Integrins
  • PARD6A protein, human
  • Receptors, Transforming Growth Factor beta
  • Smad Proteins
  • TNF Receptor-Associated Factor 6
  • Transforming Growth Factor beta
  • Extracellular Signal-Regulated MAP Kinases
  • MAP Kinase Kinase Kinases
  • MAP kinase kinase kinase 7
  • GTP Phosphohydrolases