Journal Article

A two-pore channel protein required for regulating mTORC1 activity on starvation

Dmitriev, Phillip, Gross, Julian, Wang, Yuntao, Pears, Catherine, Chang, Fu-Sheng, Galione, Antony

2020

Overview

Background Two-pore channels (TPCs) release Ca 2+ from acidic intracellular stores and are implicated in a number of diseases, but their role in development is unclear. The social amoeba Dictyostelium discoideum proliferates as single cells that aggregate to form a multicellular organism on starvation. Starvation is sensed by the mTORC1 complex which, like TPC proteins, is found on acidic vesicles. Here, we address the role of TPCs in development and under starvation. Results We report that disruption of the gene encoding the single Dictyostelium TPC protein, TPC2, leads to a delay in early development and prolonged growth in culture with delayed expression of early developmental genes, although a rapid starvation-induced increase in autophagy is still apparent. Ca 2+ signals induced by extracellular cAMP are delayed in developing tpc2 − cells, and aggregation shows increased sensitivity to weak bases, consistent with reduced acidity of the vesicles. In mammalian cells, the mTORC1 protein kinase has been proposed to suppress TPC channel opening. Here, we show a reciprocal effect as tpc2 − cells show an increased level of phosphorylation of an mTORC1 substrate, 4E-BP1. mTORC1 inhibition reverses the prolonged growth and increases the efficiency of aggregation of tpc2 − cells. Conclusion TPC2 is required for efficient growth development transition in Dictyostelium and acts through modulation of mTORC1 activity revealing a novel mode of regulation.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Acidic vesicles / Acidity / Agglomeration / Aggregates / Amoeba / Analysis / Autophagy / Biological complexity / Biomedical and Life Sciences / Calcium (extracellular) / Calcium (intracellular) / Calcium channels / Calcium Channels - genetics / Calcium Channels - metabolism / Calcium ions / Calcium signalling / Cell culture / Channel opening / Control / Dictyostelium / Dictyostelium - genetics / Dictyostelium - physiology / Disruption / Endoplasmic reticulum / Gene Expression / Influence / Ion channels / Kinases / Life Sciences / Mammalian cells / Mechanistic Target of Rapamycin Complex 1 - genetics / Mechanistic Target of Rapamycin Complex 1 - metabolism / mTORC1 / Phagocytosis / Phosphorylation / Protein kinase / Proteins / Protozoan Proteins - genetics / Protozoan Proteins - metabolism / Research Article / Signal Transduction / Starvation / Substrate inhibition / Two-pore channel (TPC) / Vesicles