Signalling mechanisms mediating Zn2+-induced TRPM2 channel activation and cell death in microglial cells

• Published in: Scientific reports Vol. 7; no. 1; p. 45032
• Main Authors: Mortadza, Sharifah Syed, Sim, Joan A., Stacey, Martin, Jiang, Lin-Hua
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 21-03-2017; Nature Publishing Group
• Subjects: 14/19; 631/378/1934; 631/443/376; 64/60; 96/95; Apoptosis; Brain injury; Calcium signalling; Cell activation; Cell death; Chelerythrine; CYBB protein; Enzyme inhibitors; Extracellular signal-regulated kinase; Feedback; Humanities and Social Sciences; Kinases; Microglia; Mortality; multidisciplinary; NAD(P)H oxidase; Poly(ADP-ribose) polymerase; Protein kinase; Protein kinase C; Science; Signal transduction; Transient receptor potential proteins; Zinc
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep45032

Excessive Zn
2+
causes brain damage via promoting ROS generation. Here we investigated the role of ROS-sensitive TRPM2 channel in H
2
O
2
/Zn
2+
-induced Ca
2+
signalling and cell death in microglial cells. H
2
O
2
/Zn
2+
induced concentration-dependent increases in cytosolic Ca
2+
concentration ([Ca
2+
]
c
), which was inhibited by PJ34, a PARP inhibitor, and abolished by TRPM2 knockout (TRPM2-KO). Pathological concentrations of H
2
O
2
/Zn
2+
induced substantial cell death that was inhibited by PJ34 and DPQ, PARP inhibitors, 2-APB, a TRPM2 channel inhibitor, and prevented by TRPM2-KO. Further analysis indicate that Zn
2+
induced ROS production, PARP-1 stimulation, increase in the [Ca
2+
]
c
and cell death, all of which were suppressed by chelerythrine, a protein kinase C inhibitor, DPI, a NADPH-dependent oxidase (NOX) inhibitor, GKT137831, a NOX1/4 inhibitor, and Phox-I2, a NOX2 inhibitor. Furthermore, Zn
2+
-induced PARP-1 stimulation, increase in the [Ca
2+
]
c
and cell death were inhibited by PF431396, a Ca
2+
-sensitive PYK2 inhibitor, and U0126, a MEK/ERK inhibitor. Taken together, our study shows PKC/NOX-mediated ROS generation and PARP-1 activation as an important mechanism in Zn
2+
-induced TRPM2 channel activation and, TRPM2-mediated increase in the [Ca
2+
]
c
to trigger the PYK2/MEK/ERK signalling pathway as a positive feedback mechanism that amplifies the TRPM2 channel activation. Activation of these TRPM2-depenent signalling mechanisms ultimately drives Zn
2+
-induced Ca
2+
overloading and cell death.