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ArfGAP1 inhibits mTORC1 lysosomal localization and activation
Delong Meng1,2,3, Qianmei Yang1,2,3, Chase H Melick1,2,3
1Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
The EMBO Journal
|May 14, 2021
Summary
ADP-ribosylation factor GTPase-activating protein 1 (ArfGAP1) inhibits cell growth by preventing mTORC1 activation and lysosomal localization. ArfGAP1 is a prognostic factor in pancreatic cancer, suggesting therapeutic potential.
Area of Science:
- Cellular metabolism and signaling
- Molecular biology
- Cancer research
Background:
- The mammalian target of rapamycin complex 1 (mTORC1) is a central regulator of cell growth and metabolism, integrating various cellular signals.
- Amino acids are known activators of mTORC1, promoting its lysosomal localization.
- The precise mechanisms governing mTORC1 regulation under nutrient-deprived conditions, particularly its subcellular localization and interacting proteins, remain incompletely understood.
Purpose of the Study:
- To identify novel regulators of mTORC1 under amino acid-deficient conditions.
- To elucidate the role of ADP-ribosylation factor GTPase-activating protein 1 (ArfGAP1) in mTORC1 signaling.
- To investigate the functional and prognostic significance of ArfGAP1 in pancreatic cancer.
Main Methods:
- Co-immunoprecipitation assays to identify interacting proteins of mTORC1.
- Immunofluorescence microscopy to determine subcellular localization of mTORC1.
- Cell growth assays to assess the impact of ArfGAP1 on proliferation.
- Bioinformatic analysis of patient data to evaluate prognostic significance.
Main Results:
- ArfGAP1 was identified as a novel interacting protein of mTORC1 specifically under amino acid-deficient conditions.
- ArfGAP1 inhibits the lysosomal localization and subsequent activation of mTORC1.
- The membrane-binding amphipathic lipid packing sensor (ALPS) motifs of ArfGAP1 are essential for its interaction with and regulation of mTORC1.
- ArfGAP1 represses cell growth via mTORC1 inhibition and serves as an independent prognostic marker for overall survival in pancreatic cancer patients.
Conclusions:
- ArfGAP1 is a critical negative regulator of mTORC1, acting by preventing its transport to lysosomes and subsequent activation.
- ArfGAP1's role in repressing cell growth and its prognostic value highlight its potential as a therapeutic target in pancreatic cancer.
- This study uncovers a new mechanism controlling mTORC1 signaling with implications for understanding cancer progression and developing novel treatment strategies.
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