JPT2: The missing link between intracellular Ca²⁺ release channels and NAADP?

Area of Science:

• Cellular biology
• Molecular signaling
• Calcium homeostasis

Background:

• Nicotinic acid adenine dinucleotide phosphate (NAADP) is a key calcium (Ca²⁺) second messenger.
• NAADP activates calcium release from endolysosomes (via TPCs) and endoplasmic reticulum (via RyR1).
• The precise mechanism of NAADP channel activation has remained elusive for over a decade.

Purpose of the Study:

• To elucidate the molecular mechanism by which NAADP activates TPCs and RyR1.
• To identify potential protein intermediaries linking NAADP to its target calcium channels.
• To resolve a long-standing debate in calcium signaling pathways.

Main Methods:

• Biochemical assays to study protein-protein interactions.
• Electrophysiological recordings to assess channel activity.
• Cell-based assays to validate the role of the identified protein.

Main Results:

• A novel protein has been identified that interacts with both NAADP and the TPCs/RyR1 channels.
• This protein appears to mediate the activation of calcium release by NAADP.
• Experimental evidence supports a direct or indirect link mediated by this protein.

Conclusions:

• The newly discovered protein is a potential missing link in NAADP signaling.
• This finding provides a mechanistic explanation for NAADP-evoked calcium release.
• Advances our understanding of calcium signaling and its regulation by second messengers.