Apoptosis signal-regulating kinase 1 activation by Nox1-derived oxidants is required for TNF? receptor endocytosis.

ABSTRACT: Tumor necrosis factor-? (TNF?) is a proinflammatory cytokine that is closely linked to the development of cardiovascular disease. TNF? activates NADPH oxidase 1 (Nox1) and reactive oxygen species (ROS), including superoxide (O2·-), production extracellularly is required for subsequent signaling in vascular smooth muscle cells (VSMCs). Apoptosis signal-regulating kinase 1 (ASK1) is a mitogen-activated protein kinase kinase kinase that is activated by oxidation of associated thioredoxin. The role of ASK1 in Nox1-mediated signaling by TNF? is poorly defined. We hypothesized that ASK1 is required for TNF? receptor endocytosis and subsequent inflammatory TNF? signaling. We employed a knockdown strategy to explore the role of ASK1 in TNF? signaling in VSMCs. siRNA targeting ASK1 had no effect on TNF?-induced extracellular O2·- production. However, siASK1 inhibited receptor endocytosis as well as phosphorylation of two endocytosis-related proteins, dynamin1 and caveolin1. Intracellular O2·- production was subsequently reduced, as were other inflammatory signaling steps including NF-?B activation, IL-6 production, inducible nitric oxide synthase and VCAM expression, and VSMC proliferation. Prolonged exposure to TNF? (24 h) increased tumor necrosis factor receptor (TNFR) subtype 1 and 2 expression, and these effects were also attenuated by siASK1. ASK1 coimmunoprecipitated with both Nox1 and the leucine rich repeat containing 8A anion channel, two essential components of the TNFR1 signaling complex. Activation of ASK1 by autophosphorylation at Thr845 occurs following thioredoxin dissociation, and this requires the presence of Nox1. Thus, Nox1 is part of the multiprotein ASK1 signaling complex. In response to TNF?, ASK1 is activated by Nox1-derived oxidants, and this plays a critical role in translating these ROS into a physiologic response in VSMCs. NEW & NOTEWORTHY Apoptosis signal-regulating kinase 1 (ASK1) drives dynamin1 and caveolin1 phosphorylation and TNF? receptor endocytosis. ASK1 modulates TNF?-induced NF-?B activation, survival, and proliferation. ASK1 and NADPH oxidase 1 (Nox1) physically associate in a multiprotein signaling complex. Nox1 is required for TNF?-induced ASK1 activation.

SUBMITTER: Choi H 

PROVIDER: S-EPMC6620688 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature