Pharmacological characterization of NAADP-induced Ca2+ signals in starfish oocytes
F Moccia1, R A Billington, Luigia Santella
1Laboratory of Cell Signaling, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy. moccia1997@hotmail.it
Abstract:
The recently discovered second messenger nicotinic acid adenine dinucleotide phosphate (NAADP) is central to the onset of intracellular Ca2+ signals induced by several stimuli, including fertilization. The nature of the Ca2+ pool mobilized by NAADP is still controversial. Depending on the cell type, NAADP may target either an acidic compartment with lysosomal properties or ryanodine receptors (RyRs) on endoplasmic reticulum. In addition, NAADP elicits a robust Ca2+ influx into starfish oocytes by activating a Ca2+-mediated current across the plasma membrane. In the present study, we employed the single-electrode intracellular recording technique to assess the involvement of either acidic organelles or RyRs in NAADP-elicited Ca2+ entry. We found that neither drugs which interfere with acidic compartments nor inhibitors of RyRs affected NAADP-induced depolarization. These data further support the hypothesis that a yet unidentified plasma membrane Ca2+ channel is the target of NAADP in starfish oocytes.
Insights
Nicotinic acid adenine dinucleotide phosphate (NAADP) triggers calcium signals. In starfish oocytes, NAADP-induced calcium entry does not involve acidic organelles or ryanodine receptors, suggesting a novel plasma membrane channel target.
Area of Science:
- Cellular Biology
- Molecular Physiology
- Signal Transduction
Background:
- Nicotinic acid adenine dinucleotide phosphate (NAADP) is a key second messenger initiating intracellular calcium (Ca2+) signals.
- The specific Ca2+ pool and molecular targets of NAADP remain debated, with possibilities including acidic organelles or ryanodine receptors (RyRs).
- NAADP is known to induce Ca2+ influx in starfish oocytes via a Ca2+-mediated current.
Purpose of the Study:
- To investigate the cellular targets of NAADP responsible for Ca2+ entry in starfish oocytes.
- To determine whether acidic compartments or RyRs are involved in NAADP-mediated Ca2+ influx.
- To identify the mechanism underlying NAADP-elicited depolarization in these cells.
Main Methods:
- Single-electrode intracellular recording technique was utilized.
- Experiments involved applying NAADP to starfish oocytes.
- The effects of acidic compartment modulators and RyR inhibitors on NAADP-induced responses were assessed.
Main Results:
- Neither drugs affecting acidic compartments nor RyR inhibitors altered NAADP-induced depolarization.
- These findings indicate that acidic organelles and RyRs are not the primary targets for NAADP-induced Ca2+ entry in this model.
- The results strongly suggest the involvement of an unknown plasma membrane Ca2+ channel.
Conclusions:
- NAADP-induced Ca2+ entry in starfish oocytes is independent of acidic organelles and RyRs.
- A novel, unidentified plasma membrane Ca2+ channel is likely the direct target of NAADP in starfish oocytes.
- This study advances the understanding of NAADP signaling pathways and Ca2+ mobilization mechanisms.
More Related Videos
10:08Microtransplantation of Synaptic Membranes to Reactivate Human Synaptic Receptors for Functional Studies
Published on: July 20, 2022
08:56Demonstration of Proteolytic Activation of the Epithelial Sodium Channel (ENaC) by Combining Current Measurements with Detection of Cleavage Fragments
Published on: July 5, 2014
