Human P2Y11 Expression Level Affects Human P2X7 Receptor-Mediated Cell Death.

Adenosine triphosphate (ATP) is known to induce cell death in T lymphocytes at high extracellular concentrations. CD4+ and CD8+ T lymphocytes have a differential response to ATP, which in mice is due to differences in the P2X7 receptor expression levels. By contrast, we observed that the difference in human CD4+ and CD8+ T lymphocyte response toward the synthetic ATP-analog BzATP is not explained by a difference in human P2X7 receptor expression. Rather, the BzATP-induced human P2X7 receptor response in naïve and immune-activated lymphocyte subtypes correlated with the expression of another ATP-binding receptor: the human P2Y11 receptor. In a recombinant expression system, the coexpression of the human P2Y11 receptor counteracted BzATP-induced human P2X7 receptor-driven lactate dehydrogenase release (a marker of cell death) and pore formation independent of calcium signaling. A mutated non-signaling human P2Y11 receptor had a similar human P2X7 receptor-inhibitory effect on pore formation, thus demonstrating that the human P2X7 receptor interference was not caused by human P2Y11 receptor signaling. In conclusion, we demonstrate an important species difference in the ATP-mediated cell death between mice and human cells and show that in human T lymphocytes, the expression of the human P2Y11 receptor correlates with human P2X7 receptor-driven cell death following BzATP stimulation.

Validation of antibodies for neuroanatomical localization of the P2Y11 receptor in macaque brain.

Focus on the purinergic receptor P2Y11 has increased following the finding of an association between the sleep disorder narcolepsy and a genetic variant in P2RY11 causing decreased gene expression. Narcolepsy is believed to arise from an autoimmune destruction of the hypothalamic neurons that produce the neuropeptide hypocretin/orexin. It is unknown how a decrease in expression of P2Y11 might contribute to an autoimmune reaction towards the hypocretin neurons and the development of narcolepsy. To advance narcolepsy research it is therefore extremely important to determine the neuroanatomical localization of P2Y11 in the brain with particular emphasis on the hypocretin neurons. In this article we used western blot, staining of blood smears, and flow cytometry to select two antibodies for immunohistochemical staining of macaque monkey brain. Staining was seen in neuron-like structures in cortical and hypothalamic regions. Rats do not have a gene orthologue to the P2Y11 receptor and therefore rat brain was used as negative control tissue. The chromogenic signal observed in macaque monkey brain in neurons was not considered reliable, because the antibodies stained rat brain in a similar distribution pattern. Hence, the neuroanatomical localization of the P2Y11 receptor remains undetermined due to the lack of specific P2Y11 antibodies for brain immunohistochemistry.