Abstract

mTORC1 senses nutrients and growth factors and phosphorylates downstream targets, including the transcription factor TFEB, to coordinate metabolic supply and demand. These functions position mTORC1 as a central controller of cellular homeostasis, but the behavior of this system in individual cells has not been well characterized. Here, we provide measurements necessary to refine quantitative models for mTORC1 as a metabolic controller. We developed a series of fluorescent protein-TFEB fusions and a multiplexed immunofluorescence approach to investigate how combinations of stimuli jointly regulate mTORC1 signaling at the single-cell level. Live imaging of individual MCF10A cells confirmed that mTORC1-TFEB signaling responds continuously to individual, sequential, or simultaneous treatment with amino acids and the growth factor insulin. Under physiologically relevant concentrations of amino acids, we observe correlated fluctuations in TFEB, AMPK, and AKT signaling that indicate continuous activity adjustments to nutrient availability. Using partial least squares regression modeling, we show that these continuous gradations are connected to protein synthesis rate via a distributed network of mTORC1 effectors, providing quantitative support for the qualitative model of mTORC1 as a homeostatic controller and clarifying its functional behavior within individual cells.

Data availability

The following files contain the per-cell fluorescence intensity data, extracted from microscope image data, that were used to generate each figure in the paper:Sparta2023_Figure1_SourceData1.xlsSparta2023_Figure1_SourceData2.xlsSparta2023_Figure2_SourceData1.xlsxSparta2023_Figure3_SourceData1.xlsSparta2023_Figure4_SourceData1.xlsxSparta2023_Figure4_SourceData2.xlsxSparta2023_Figure4_SourceData3.xlsxSparta2023_Figure4_SourceData4.xlsxSparta2023_Figure4_SourceData5.xlsxSparta2023_Figure4_SourceData6.xlsxSparta2023_Figure5_SourceData1.xlsxSparta2023_Figure5_SourceData2.xlsxSparta2023_Figure5_SourceData3.xlsxSparta2023_Figure5_SourceData4.xlsxSparta2023_Figure6_SourceData1.xlsx

Article and author information

Author details

  1. Breanne Sparta

    Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
    Competing interests
    No competing interests declared.
  2. Nont Kosaisawe

    Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
    Competing interests
    No competing interests declared.
  3. Michael Pargett

    Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
    Competing interests
    No competing interests declared.
  4. Madhura Patankar

    Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
    Competing interests
    No competing interests declared.
  5. Nicholaus DeCuzzi

    Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
    Competing interests
    No competing interests declared.
  6. John G Albeck

    Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
    For correspondence
    jgalbeck@ucdavis.edu
    Competing interests
    John G Albeck, John Albeck has received research grants from Kirin Corporation..
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-2688-8653

Funding

National Institute of General Medical Sciences (R35GM139621)

  • John G Albeck

National Institute of General Medical Sciences (R01GM115650)

  • John G Albeck

National Science Foundation (2136040)

  • John G Albeck

National Heart, Lung, and Blood Institute (T32HL007013)

  • Nicholaus DeCuzzi

National Institute of General Medical Sciences (F31GM120937)

  • Breanne Sparta

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Ivan Topisirovic, Jewish General Hospital, Canada

Version history

  1. Preprint posted: August 8, 2021 (view preprint)
  2. Received: October 21, 2021
  3. Accepted: September 11, 2023
  4. Accepted Manuscript published: September 12, 2023 (version 1)
  5. Version of Record published: October 3, 2023 (version 2)

Copyright

© 2023, Sparta et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Breanne Sparta
  2. Nont Kosaisawe
  3. Michael Pargett
  4. Madhura Patankar
  5. Nicholaus DeCuzzi
  6. John G Albeck
(2023)
Continuous sensing of nutrients and growth factors by the mTORC1-TFEB axis
eLife 12:e74903.
https://doi.org/10.7554/eLife.74903

Share this article

https://doi.org/10.7554/eLife.74903

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