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Title: SnRK1 activates autophagy via the TOR signaling pathway in Arabidopsis thaliana

Autophagy is a degradation process in which cells break down and recycle their cytoplasmic contents when subjected to environmental stress or during cellular remodeling. The Arabidopsis thaliana SnRK1 complex is a protein kinase that senses changes in energy levels and triggers downstream responses to enable survival. Its mammalian ortholog, AMPK, and yeast ortholog, Snf-1, activate autophagy in response to low energy conditions. We therefore hypothesized that SnRK1 may play a role in the regulation of autophagy in response to nutrient or energy deficiency in Arabidopsis. To test this hypothesis, we determined the effect of overexpression or knockout of the SnRK1 catalytic subunit KIN10 on autophagy activation by abiotic stresses, including nutrient deficiency, salt, osmotic, oxidative, and ER stress. While wild-type plants had low basal autophagy activity in control conditions, KIN10 overexpression lines had increased autophagy under these conditions, indicating activation of autophagy by SnRK1. A kin10 mutant had a basal level of autophagy under control conditions similar to wild-type plants, but activation of autophagy by most abiotic stresses was blocked, indicating that SnRK1 is required for autophagy induction by a wide variety of stress conditions. In mammals, TOR is a negative regulator of autophagy, and AMPK acts to activate autophagymore » both upstream of TOR, by inhibiting its activity, and in a parallel pathway. Inhibition of Arabidopsis TOR leads to activation of autophagy; inhibition of SnRK1 did not block this activation. Furthermore, an increase in SnRK1 activity was unable to induce autophagy when TOR was also activated. The results presented here demonstrate that SnRK1 acts upstream of TOR in the activation of autophagy in Arabidopsis.« less
 [1] ; ORCiD logo [2]
  1. Iowa State Univ., Ames, IA (United States). Dept. of Genetics, Development, and Cell Biology
  2. Iowa State Univ., Ames, IA (United States). Dept. of Genetics, Development, and Cell Biology and Plant Sciences Inst.
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Additional Journal Information:
Journal Volume: 12; Journal Issue: 8; Journal ID: ISSN 1932-6203
Public Library of Science
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Iowa State Univ., Ames, IA (United States)
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United States
59 BASIC BIOLOGICAL SCIENCES; Autophagic cell death; Seedlings; Plant resistance to abiotic stress; Arabidopsis thaliana; Liquid chromatography-mass spectrometry; Osmotic shock; Regulator genes; Sucrose
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OSTI ID: 1425736