Control of macroautophagy by calcium, calmodulin-dependent kinase kinase-beta, and Bcl-2

Mol Cell. 2007 Jan 26;25(2):193-205. doi: 10.1016/j.molcel.2006.12.009.

Abstract

Macroautophagy is an evolutionary conserved lysosomal pathway involved in the turnover of cellular macromolecules and organelles. In spite of its essential role in tissue homeostasis, the molecular mechanisms regulating mammalian macroautophagy are poorly understood. Here, we demonstrate that a rise in the free cytosolic calcium ([Ca(2+)](c)) is a potent inducer of macroautophagy. Various Ca(2+) mobilizing agents (vitamin D(3) compounds, ionomycin, ATP, and thapsigargin) inhibit the activity of mammalian target of rapamycin, a negative regulator of macroautophagy, and induce massive accumulation of autophagosomes in a Beclin 1- and Atg7-dependent manner. This process is mediated by Ca(2+)/calmodulin-dependent kinase kinase-beta and AMP-activated protein kinase and inhibited by ectopic Bcl-2 located in the endoplasmatic reticulum (ER), where it lowers the [Ca(2+)](ER) and attenuates agonist-induced Ca(2+) fluxes. Thus, an increase in the [Ca(2+)](c) serves as a potent inducer of macroautophagy and as a target for the antiautophagy action of ER-located Bcl-2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinases
  • Adenosine Triphosphate / pharmacology
  • Autophagy / drug effects*
  • Autophagy / physiology*
  • Autophagy-Related Protein 7
  • Base Sequence
  • Calcitriol / analogs & derivatives
  • Calcitriol / pharmacology
  • Calcium / metabolism*
  • Calcium Signaling
  • Calcium-Calmodulin-Dependent Protein Kinase Kinase
  • Cell Line
  • Endoplasmic Reticulum / metabolism
  • HeLa Cells
  • Humans
  • Ionomycin / pharmacology
  • Microscopy, Electron
  • Models, Biological
  • Multienzyme Complexes / metabolism
  • Protein Kinases / metabolism
  • Protein-Serine-Threonine Kinases / metabolism*
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • RNA, Small Interfering / genetics
  • Signal Transduction
  • TOR Serine-Threonine Kinases
  • Ubiquitin-Activating Enzymes / genetics
  • Ubiquitin-Activating Enzymes / metabolism

Substances

  • Multienzyme Complexes
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Small Interfering
  • Ionomycin
  • Adenosine Triphosphate
  • Protein Kinases
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • Protein-Serine-Threonine Kinases
  • CAMKK2 protein, human
  • Calcium-Calmodulin-Dependent Protein Kinase Kinase
  • AMP-Activated Protein Kinases
  • Atg7 protein, human
  • Autophagy-Related Protein 7
  • Ubiquitin-Activating Enzymes
  • Calcitriol
  • seocalcitol
  • Calcium