Dinucleoside polyphosphates and their interaction with other nucleotide signaling pathways

Area of Science:

• Neuroscience
• Molecular Biology
• Cell Signaling

Background:

• Dinucleoside polyphosphates, such as Ap(4)A, Ap(5)A, and Ap(6)A, are co-released with neurotransmitters from secretory vesicles.
• Extracellularly, these dinucleotides interact with both ATP receptors (P2Y, P2X) and specific dinucleotide receptors.

Purpose of the Study:

• To investigate the specific receptors and signaling pathways activated by dinucleoside polyphosphates in the central nervous system (CNS).
• To elucidate the physiological roles of dinucleoside polyphosphates beyond their interaction with ATP receptors.

Main Methods:

• Characterization of ionotropic dinucleotide receptors in rat midbrain presynaptic terminals.
• Analysis of calcium influx and neurotransmitter release upon dinucleotide receptor activation.
• Investigation of Ap(5)A-mediated signaling in cerebellar synaptosomes, neurons, and astrocytes, including CaMKII and ERK pathway activation.

Main Results:

• Specific ionotropic dinucleotide receptors in presynaptic terminals mediate calcium entry and subsequent neurotransmitter release.
• Ap(5)A induces calcium signals and CaMKII activation in cerebellar neurons, and ERK activation in astrocytes via a pertussis toxin-insensitive pathway involving src and ras.
• Dinucleoside polyphosphates interact with both specific dinucleotide receptors and ATP receptors, influencing various neurotransmitter systems.

Conclusions:

• Dinucleoside polyphosphates exert diverse effects in the CNS through distinct receptor pathways.
• The identified specific dinucleotide receptors and their downstream signaling cascades highlight novel mechanisms of neuronal and glial communication.
• Further research is needed to fully determine the physiological significance of dinucleoside polyphosphates in the CNS.