E3-14.7K Is Recruited to TNF-Receptor 1 and Blocks TNF Cytolysis Independent from Interaction with Optineurin

Abstract

Escape from the host immune system is essential for intracellular pathogens. The adenoviral protein E3-14.7K (14.7K) is known as a general inhibitor of tumor necrosis factor (TNF)-induced apoptosis. It efficiently blocks TNF-receptor 1 (TNFR1) internalization but the underlying molecular mechanism still remains elusive. Direct interaction of 14.7K and/or associated proteins with the TNFR1 complex has been discussed although to date not proven. In our study, we provide for the first time evidence for recruitment of 14.7K and the 14.7K interacting protein optineurin to TNFR1. Various functions have been implicated for optineurin such as regulation of receptor endocytosis, vesicle trafficking, regulation of the nuclear factor κB (NF-κB) pathway and antiviral signaling. We therefore hypothesized that binding of optineurin to 14.7K and recruitment of both proteins to the TNFR1 complex is essential for protection against TNF-induced cytotoxic effects. To precisely dissect the individual role of 14.7K and optineurin, we generated and characterized a 14.7K mutant that does not confer TNF-resistance but is still able to interact with optineurin. In H1299 and KB cells expressing 14.7K wild-type protein, neither decrease in cell viability nor cleavage of caspases was observed upon stimulation with TNF. In sharp contrast, cells expressing the non-protective mutant of 14.7K displayed reduced viability and cleavage of initiator and effector caspases upon TNF treatment, indicating ongoing apoptotic cell death. Knockdown of optineurin in 14.7K expressing cells did not alter the protective effect as measured by cell viability and caspase activation. Taken together, we conclude that optineurin despite its substantial role in vesicular trafficking, endocytosis of cell surface receptors and recruitment to the TNFR1 complex is dispensable for the 14.7K-mediated protection against TNF-induced apoptosis.

Visual impairment in an optineurin mouse model of primary open-angle glaucoma

“…Alternatively, optineurin might alter NFκB activity (Sudhakar, et al, 2009, Zhu, et al, 2007). Signaling components of the NFκB pathway, such as TNFα and TBK1, are also associated with glaucoma and interacts with optineurin (Klingseisen, et al, 2012, Morton, et al, 2008, Tezel, et al, 2001). Other functions for optineurin include: a K63-polyubiquitin-chain binding protein (Nagabhushana, et al, 2011, Zhu, et al, 2007), a negative checkpoint for cytokinesis (Kachaner, et al, 2012), and an autophagy/mitophagy receptor (Korac, et al, 2013, Wild, et al, 2011, Wong and Holzbaur, 2014).…”

Unveiling sex-based differences in Parkinson's disease: a comprehensive meta-analysis of transcriptomic studies

“…The remaining 4 genes displaying a significant increase in female PD patients (OPTN, UBA6, BZW1, and TMX2) have been linked to apoptosis, ubiquitination, and mitochondrial activity. OPTN interacts with adenovirus E3-14.7K protein and mediates apoptosis, inflammation, and vasoconstriction through tumor necrosis factor-alpha or Fas-ligand pathways [ 82 ]. Several viruses have been related to the etiology of neural diseases, although the underlying mechanisms remain incompletely understood [ 83 , 84 ].…”

Unveiling Sex-based Differences in Parkinson’s Disease: A Comprehensive Meta-analysis of Transcriptomic Studies

“…It´s described that Optineurin (OPTN) interacts with adenovirus E3-14.7K protein and through tumor necrosis factor-alpha or Fas-ligand pathways mediate apoptosis, inflammation or vasoconstriction. Several viruses have been related to etiology of neural diseases although the mechanisms underlying are unknown [67]- [69]. Ubiquitin dysregulation can affect normal PINK1 and Parkin functions that govern mitochondrial quality control and mitophagy process [70].…”