Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP) and Ca²⁺ Mobilization

Abstract

Many physiological processes are controlled by a great diversity of Ca^{2 +} signals that depend on Ca^{2 +} entry into the cell and/or Ca^{2 +} release from internal Ca^{2 +} stores. Ca^{2 +} mobilization from intracellular stores is gated by a family of messengers including inositol-1,4,5-trisphosphate (InsP₃), cyclic ADP-ribose (cADPR), and nicotinic acid adenine dinucleotide phosphate (NAADP). There is increasing evidence for a novel intracellular Ca^{2 +} release channel that may be targeted by NAADP and that displays properties distinctly different from the well-characterized InsP₃ and ryanodine receptors. These channels appear to localize on a wider range of intracellular organelles, including the acidic Ca^{2 +} stores. Activation of the NAADP-sensitive Ca^{2 +} channels evokes complex changes in cytoplasmic Ca^{2 +} levels by means of channel chatter with other intracellular Ca^{2 +} channels. The recent demonstration of changes in intracellular NAADP levels in response to physiologically relevant extracellular stimuli highlights the significance of NAADP as an important regulator of intracellular Ca^{2 +} signaling.

Key Words: :

• Calcium
• Nicotinic acid adenine dinucleotide phosphate (NAADP)
• ADP-rybosyl cyclase (ADPRC)
• Endoplasmic reticulum (ER)
• Lysosomes

Abbreviations
ADPRC	=	ADP-ribosyl cyclase enzyme family
cADPR	=	cyclic adenosine disphosphate ribose
CICR	=	Ca2 +-induced Ca2 + release
ER	=	endoplasmic reticulum
InsP3	=	D-myo-inositol-1,4,5-trisphosphate
HSR	=	heavy sarcoplasmic reticulum
NAADP	=	nicotinic acid adenine dinucleotide phosphate
SERCA	=	sarco(endo)plasmic reticulum Ca2 +-ATPase
RuRed	=	ruthenium red
RyR	=	ryanodine receptor

Abbreviations
ADPRC	=	ADP-ribosyl cyclase enzyme family
cADPR	=	cyclic adenosine disphosphate ribose
CICR	=	Ca2 +-induced Ca2 + release
ER	=	endoplasmic reticulum
InsP3	=	D-myo-inositol-1,4,5-trisphosphate
HSR	=	heavy sarcoplasmic reticulum
NAADP	=	nicotinic acid adenine dinucleotide phosphate
SERCA	=	sarco(endo)plasmic reticulum Ca2 +-ATPase
RuRed	=	ruthenium red
RyR	=	ryanodine receptor