P2X7 receptor-pannexin 1 interaction mediates extracellular alpha-synuclein-induced ATP release in neuroblastoma SH-SY5Y cells

Abstract

Abnormalities of alpha-synuclein (ASN), the main component of protein deposits (Lewy bodies), were observed in Parkinson’s disease (PD), dementia with Lewy bodies, Alzheimer’s disease, and other neurodegenerative disorders. These alterations include increase in the levels of soluble ASN oligomers in the extracellular space. Numerous works have identified several mechanisms of their toxicity, including stimulation of the microglial P2X7 receptor leading to oxidative stress. While the significant role of purinergic signaling—particularly, P2 family receptors—in neurodegenerative disorders is well known, the interaction of extracellular soluble ASN with neuronal purinergic receptors is yet to be studied. Therefore, in this study, we have investigated the effect of ASN on P2 purinergic receptors and ATP-dependent signaling. We used neuroblastoma SH-SY5Y cell line and rat synaptoneurosomes treated with exogenous soluble ASN. The experiments were performed using spectrofluorometric, radiochemical, and immunochemical methods. We found the following: (i) ASN-induced intracellular free calcium mobilization in neuronal cells and nerve endings depends on the activation of purinergic P2X7 receptors; (ii) activation of P2X7 receptors leads to pannexin 1 recruitment to form an active complex responsible for ATP release; and (iii) ASN greatly decreases the activity of extracellular ecto-ATPase responsible for ATP degradation. Thus, it is concluded that purinergic receptors might be putative pharmacological targets in the molecular mechanism of extracellular ASN toxicity. Interference with P2X7 signaling seems to be a promising strategy for the prevention or therapy of PD and other neurodegenerative disorders.

P2X7 Receptors Amplify CNS Damage in Neurodegenerative Diseases

“…The microglial cell line BV2 and primary cultured microglia responded to α-synuclein with NADPH oxidase activation [ 189 ]. The activation of NADPH oxidase depended on the presence of P2X7Rs and has led to the cleavage of caspase-3 in the dopaminergic cell line SH-SY5Y [ 190 ]. The oxidative damage by α-synuclein of SH-SY5Y cells was due to P2X7R activation and the simultaneously occurring increased release of ATP as well as its decreased degradation by ecto-ATPase.…”

Connexin43- and Pannexin-Based Channels in Neuroinflammation and Cerebral Neuropathies

“…A recent study showed that extracellular ASN neurotoxicity is mediated by the P2X7 receptor signaling complex. Treatment of neuroblastoma cells and rat synaptoneurosomes with exogenous ASN activated P2X7 receptors leading to Panx 1 recruitment responsible for ATP release that could lead to neurotoxicity (Wilkaniec et al, 2017 ).…”

Papel do receptor B2 de cininas na terapia da neurodegeneração dopaminérgica em modelo animal

“…Moreover, P2X1 receptor activation induced lysosomal dysfunction that seems to be involved in αsynuclein aggregation, since it delayed protein turnover and led to its accumulation (Gan et al, 2015). Although P2X7 receptor blockade did not result in reduction of α-synuclein aggregation in this study, ATP release triggered by α-synuclein in vitro activated the P2X7 receptor and mobilized the release of intracellular Ca 2+ , showing that P2X7 receptor activation is a consequence of α-synuclein aggregation (Wilkaniec et al, 2017). Additionally, another study showed that microglial cells challenged with αsynuclein presented increased ROS production through P2X7 receptor activation, which was prevented in the presence of a receptor antagonist (Jiang et al, 2015).…”