BiP links TOR signaling to ER stress in Chlamydomonas

Plant Signal Behav. 2012 Feb;7(2):273-5. doi: 10.4161/psb.18767. Epub 2012 Feb 1.

Abstract

The highly conserved target of rapamycin (TOR) Ser/Thr kinase promotes protein synthesis under favorable growth conditions in all eukaryotes. Downregulation of TOR signaling in the model unicellular green alga Chlamydomonas reinhardtii has recently revealed a link between control of protein synthesis, endoplasmic reticulum (ER) stress and the reversible modification of the BiP chaperone by phosphorylation. Inhibition of protein synthesis by rapamycin or cycloheximide resulted in the phosphorylation of BiP on threonine residues while ER stress induced by tunicamycin or heat shock caused the fast dephosphorylation of the protein. Regulation of BiP function by phosphorylation/dephosphorylation events was proposed in early studies in mammalian cells although no connection to TOR signaling has been established so far. Here I will discuss about the coordinated regulation of BiP modification by TOR and ER stress signals in Chlamydomonas.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chlamydomonas reinhardtii / metabolism*
  • Chlamydomonas reinhardtii / physiology
  • Endoplasmic Reticulum Stress / physiology*
  • Heat-Shock Proteins / metabolism*
  • Phosphorylation
  • Plant Proteins / metabolism*
  • Protein Biosynthesis*
  • Signal Transduction
  • Stress, Physiological*
  • TOR Serine-Threonine Kinases / metabolism*
  • Threonine / metabolism

Substances

  • Heat-Shock Proteins
  • Plant Proteins
  • Threonine
  • TOR Serine-Threonine Kinases
  • molecular chaperone GRP78