Plant Vacuolar and Human Endolysosomal Two-Pore Channels: Similarities and Differences

Area of Science:

• Cellular Biology
• Ion Channel Physiology
• Molecular Mechanisms

Background:

• Two-pore channels (TPCs) are conserved across species, mediating ion fluxes in endomembrane systems.
• Plant TPCs, like AtTPC1, are voltage-dependent and Ca2+-regulated, with roles in signaling and stress.
• Human TPCs (HsTPC1, HsTPC2) are found in endosomes/lysosomes, regulated by PI(3,5)P2, and selective for Na+.

Purpose of the Study:

• To review the known functions and regulatory mechanisms of TPCs in plants and humans.
• To highlight the emerging roles of human TPCs in cellular trafficking, signaling, and disease.
• To identify knowledge gaps in TPC regulation and physiological integration.

Main Methods:

• Patch-clamp electrophysiology on isolated plant vacuoles.
• Functional characterization of human TPC isoforms (HsTPC1, HsTPC2).
• Investigation of regulatory molecules like PI(3,5)P2 and NAADP.

Main Results:

• Plant TPCs contribute to systemic signaling and stress responses.
• Human TPCs are involved in endolysosomal trafficking, membrane fusion, and intracellular signaling.
• Human TPCs exhibit Ca2+-dependent non-selective cation conductance via NAADP.

Conclusions:

• TPCs are vital for intracellular ion homeostasis and cellular functions.
• Precise regulatory mechanisms and integrated physiological roles of TPCs require further elucidation.
• Understanding TPCs offers insights into immunity, metabolism, and disease pathogenesis.