Aeromonas hydrophila-induced alterations in cytosolic calcium activate pro-apoptotic cPKC-MEK1/2-TNF alpha axis in infected headkidney macrophages of Clarias gariepinus

摘要

Alterations in intracellular-calcium (Ca2+)(i) homeostasis is critical to Aeromonas hydrophila-induced headkidney macrophages (HKM) apoptosis of Clarias gariepinus,,though the implications are poorly understood. Here, we describe the role of intermediate molecules of Ca2+- signaling pathway that are involved in HKM apoptosis. We observed phosphoinositide-3-kinaseiphospholipase C is critical for (Ca2+)(i) release in infected HKM. Heightened protein kinase-C (PKC) activity and phosphorylation of MEK1/2-ERK1/2 was noted which declined in presence of 2APB, Go6976 and PD98059, inhibitors to 1P3 receptor, conventional PKC isoforms (cPKC) and MEK1/2 respectively implicating Ca2+-/cPKC/MEK-ERK1/2 axis imperative in A. hydrophila-induced HKM apoptosis. Significant tumor necrosis factora (TNF alpha) production and its subsequent reduction in presence of MEK-ERK1/2 inhibitor U0126 suggested TNFa production downstream to cPKC-mediated signaling via MEK1/2-ERK1/2 pathway. RNAi and inhibitor studies established the role of TNFa in inducing caspase-8-mediated apoptosisof infected HKM: We conclude, alterations in A. hydrophila-induced (Ca2+)(i) alterations activate cPICC-MEK1/2-ERK1/2-TNF alpha signaling cascade triggering HKM apoptosis. (C) 2017 Elsevier Ltd. All rights reserved.