Reference: Dai, L., Wang, B., Wang, T., Meyer, E. H., Kettel, V., Hoffmann, N., ... & Zhang, Y. (2022). The TOR complex controls ATP levels to regulate actin cytoskeleton dynamics in Arabidopsis. Proceedings of the National Academy of Sciences, 119(38), e2122969119.
TOR (Target of Rapamycin) complex has been known to be an information hub to integrate different nutrition and energy signals, and serves as a master regulator for multiple downstream cellular processes. The actin cytoskeleton in plant cells is highly dynamic, with rapid changes of its organization and constant turnover between its monomeric and filamentous forms, which requires large energy supply. While both TOR complex and actin cytoskeleton dynamics relate to energy level, little is known about the connection between the TOR complex and actin cytoskeleton dynamics. In this recent work from Dai et al. from Yi Zhang lab, the connection of TOR complex (TORC1) and actin cytoskeleton dynamics in Arabidopsis have been established. Using spinning-disc confocal microscopy, the authors studied the actin filament dynamics under impaired TORC1 conditions and ATP-deficient conditions. Impairment of TORC1 by genetic mutations and TOR inhibitor treatment led to decreased actin cytoskeleton dynamics quantified by correlation coefficient, and reduced sensitivity to actin inhibitors (Latrunculin B and cytochalasin D). But the organization of actin cytoskeleton was not altered, in terms of density and skewness. To fill in the gap between TORC1 function and actin filament dynamics, the authors showed that inhibition of TORC1 functions led to reduced ATP levels, and actin filaments displayed reduced dynamics in ATP-deficient conditions. Further, exogenous feeding of adenine partially rescues the actin filament dynamics upon TORC1 function impairment. Additionally, the authors examined the subcellular localization of an important component of the TOR complex, RAPTOR1B, using fluorescence marker tagged functional complementation lines. The subcellular localization of RAPTOR1B was revealed to be cytosol and mitochondria surface. (Summary by Xiaohui Li) PNAS 10.1073/pnas.2122969119
TOR (Target of Rapamycin) complex has been known to be an information hub to integrate different nutrition and energy signals, and serves as a master regulator for multiple downstream cellular processes. The actin cytoskeleton in plant cells is highly dynamic, with rapid changes of its organization and constant turnover between its monomeric and filamentous forms, which requires large energy supply. While both TOR complex and actin cytoskeleton dynamics relate to energy level, little is known about the connection between the TOR complex and actin cytoskeleton dynamics. In this recent work from Dai et al. from Yi Zhang lab, the connection of TOR complex (TORC1) and actin cytoskeleton dynamics in Arabidopsis have been established. Using spinning-disc confocal microscopy, the authors studied the actin filament dynamics under impaired TORC1 conditions and ATP-deficient conditions. Impairment of TORC1 by genetic mutations and TOR inhibitor treatment led to decreased actin cytoskeleton dynamics quantified by correlation coefficient, and reduced sensitivity to actin inhibitors (Latrunculin B and cytochalasin D). But the organization of actin cytoskeleton was not altered, in terms of density and skewness. To fill in the gap between TORC1 function and actin filament dynamics, the authors showed that inhibition of TORC1 functions led to reduced ATP levels, and actin filaments displayed reduced dynamics in ATP-deficient conditions. Further, exogenous feeding of adenine partially rescues the actin filament dynamics upon TORC1 function impairment. Additionally, the authors examined the subcellular localization of an important component of the TOR complex, RAPTOR1B, using fluorescence marker tagged functional complementation lines. The subcellular localization of RAPTOR1B was revealed to be cytosol and mitochondria surface. (Summary by Xiaohui Li) PNAS 10.1073/pnas.2122969119