ATG5: From Autophagy to Alzheimer's Disease

Fri, 08/30/2013 - 08:42

Autophagy is a conserved mechanism whereby cells form double membrane autophagosomes to sequester cytoplasmic components for subsequent destruction by fusion with lysosomes (eukaryotes) or vacuoles (yeast). Targets of autophagy include aging proteins, damaged organelles and invasive pathogens, and the resulting breakdown products can be recycled back to the cytoplasm for re-use under conditions of starvation (1). Autophagy is critical for cell survival and homeostasis, and is up-regulated in response to cellular stresses such as growth factor deprivation or pathogen infection. However, a number of pathological conditions are associated with defective autophagy including cancer, neurodegeneration and cardiovascular disorders (2).

In mammalian systems autophagy consists of a number of sequential steps that are known to be regulated by more than thirty genes (3). Broadly, the stages of autophagy consist of induction, autophagosome formation and fusion with the lysosome; ATG5 (autophagy protein 5) is involved in autophagosome formation. The covalent binding of ATG5 to ATG12 is catalyzed by ATG7; the ATG5-ATG12 dimer subsequently forms a complex with ATG16 and is recruited to the autophagosome membrane where it promotes membrane expansion (2).

Immunocytochemistry/Immunofluorescence: ATG5 Antibody Immunocytochemistry/Immunofluorescence: ATG5 Antibody

Zheng, et. al. have investigated the effects of knocking down expression of the ATG5 protein using ATG5 RNAi. They exposed SH-SY5Y neuroblastoma cells to hyperoxic conditions for 5 days to trigger autophagy, and demonstrated enhanced apoptosis and the accumulation of amyloid beta protein in lysosomes. Oxidative stress and intracellular amyloid build up in neurons are heavily implicated in Alzheimer’s disease, but by down-regulating ATG5 the effects of these were prevented. The ATG5 knockdown was demonstrated by Western blotting and by immunocytochemistry using ATG5 antibodies; these results provide evidence that targeting ATG5 may be one mechanism of preventing intralysosomal accumulation of amyloid proteins and the resulting apoptosis of neurons (4).

  1. PMID: 19653858
  2. PMID: 22275084
  3. PMID: 22257882
  4. PMID: 22108004

Novus Biologicals offers various ATG5 reagents for your research needs including:

Written by Emma Easthope

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