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Growing Macrophages Regulate High Rates of Solute Flux by Pinocytosis
Biniam M Tebeje1, Natalie W Thiex2, Joel A Swanson1
1Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109-5620.
Biorxiv : the Preprint Server for Biology
|November 1, 2024
Summary
Growth factors stimulate solute uptake via pinocytosis in cells. This study shows pinocytosis is crucial for cell growth and nutrient uptake, regulated by nutrient availability and mTOR signaling.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Growth factors stimulate solute uptake through pinocytosis in metazoan cells.
- Pinocytosis plays a role in cell growth and nutrient acquisition.
Purpose of the Study:
- To investigate the role of pinocytosis in cell proliferation.
- To measure solute flux rates by pinocytosis in response to colony-stimulating factor-1 (CSF1).
Main Methods:
- Murine macrophages were cultured and treated with CSF1.
- Cell proliferation and solute flux rates were measured.
- Inhibitors of pinocytosis and mTOR were used.
Main Results:
- Macrophages internalized 72% of their cell volume in fluid per hour during CSF1-dependent growth.
- Leucine deprivation increased macropinocytosis but limited protein synthesis and growth.
- Pinocytosis capacity was insufficient to support leucine needs for growth.
- Lysosomal recycling secreted small molecules, and mTOR inhibitors reduced growth and recycling.
Conclusions:
- Pinocytosis is essential for cell growth and nutrient uptake.
- Nutrient sensing regulates solute flux via pinocytosis, involving mTOR signaling.
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