STING complex

About: STING complex is a research topic. Over the lifetime, 9 publications have been published within this topic receiving 441 citations.

Single Mutations Reshape the Structural Correlation Network of the DMXAA-Human STING Complex.

Abstract: Subtle changes in protein sequences are able to alter ligand–protein interactions. Unraveling the mechanism of such phenomena is important for understanding ligand–protein interactions, including the DMXAA–STING interaction. DMXAA specifically binds to mouse STING instead of human STING. However, the S162A mutation and a newly discovered E260I mutation endow human STINGAQ with DMXAA sensitivity. Through molecular dynamics simulations, we revealed how these single mutations alter the DMXAA–STING interaction. Compared to mutated systems, structural correlations in the interaction of STINGAQ with DMXAA are stronger, and the correlations are cross-protomers in the dimeric protein. Analyses on correlation coefficients lead to the identification of two key interactions that mediate the strong cross-protomer correlation in the DMXAA–STINGAQ interaction network: DMXAA–267T–162S* and 238R–260E*. These two interactions are partially and totally interrupted by the S162A and E260I mutations, respectively. Moreover, a...

Abstract 5393: Association of heat shock proteins as chaperone for STING: A potential link in a key immune activation mechanism revealed by the novel anti-cancer agent PV-10

Abstract: Introduction: The activation of stimulator of interferon (IFN) genes (STING), an intracellular receptor system located in the endoplasmic reticulum, has been shown to augment antitumor immunity through the induction of pro-inflammatory cytokines. Currently, a number of STING agonists have been developed to treat refractory malignancies. Our previous studies have identified PV-10 (4,5,6,7-tetrachloro-29,49,59,79-tetraiodofluorescein) as a novel therapeutic agent with potent activity following intra-tumoral injection. Here we describe a previously unidentified mechanism by which PV-10 may facilitate sustained immune activation and therapeutic antitumor activity. Methods: The well-established acute monocytic leukemia (AML) cell line THP-1 was used as a model to study STING activation in vitro. Cells were treated with PV-10 and the induction of STING was evaluated by Western blot analysis using cGAMP as a positive control. Proteins that associate with STING in the presence of PV-10 were purified by immunoprecipitation and analyzed by mass spectrometry (LC-MS/MS, Mascot database). The culture supernatants from PV-10 treated cells were probed for a panel of 42 immune cytokines using the Bio-Plex multiplex bead-based assay system. Results: We show that the exposure of THP-1 cells to PV-10 leads to the appearance of a new 70-KD STING dimer band detected by specific antibodies. Compared to cGAMP controls no induction of PDL-1 was noted. Mass spectrometric analysis of immuno-precipitates of STING in these cells showed the presence of Heat Shock Proteins (HSP) 60, 70 and 90 as well as Polyadenylate Binding Protein 1 (PABP1) to the dimerized STING complex. The chemokine assays showed specific upregulation of a distinct set of pro-inflammatory and cytotoxic T-cell recruitment cytokines. A peak in the induction of MCP-3 and IFN gamma was seen at 24 hours (2 fold) and an approximately 10-fold increase in IL-6, IL-8 and IP-10 was seen in the 24 hours following exposure to PV-10. A significant increase in MCP-1 levels was also noted. Discussion: The compound PV-10 has been shown to induce tumor necrosis following intra-tumoral injection. Our present data show a possible mechanism of this agent through STING dimerization and HSP association leading to a sustained pro-inflammatory and immune response. We provide experimental data, for the first time, for a role of HSPs in STING-mediated immune activation pathways and the description of an agent that may play a role in effective single-agent immunotherapy or drug combination therapy approaches in future clinical studies. Citation Format: Satbir Thakur, Chunfen Zhang, Laurent Brechenmacher, Luis Murgia-Favela, Aru Narendran. Association of heat shock proteins as chaperone for STING: A potential link in a key immune activation mechanism revealed by the novel anti-cancer agent PV-10 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5393.

Role of STING complex in differential retrograde signaling in cybrids with K versus H haplogroup mtDNA

Abstract: Mitochondrial (mt) DNA haplogroups, defined by specific single nucleotide polymorphism (SNPs) patterns, represent populations of diverse geographic origins and may play a role in disparate disease susceptibilities found in different ethnic/racial populations The most common European haplogroup is H, while the K haplogroup is highly associated with Ashkenazi Jewish populations Studies using transmitochondrial cybrids (cell lines with identical nuclei but mitochondria from either H or K haplogroup subjects) demonstrated significant molecular and biological differences but mechanisms for these disparities are unclear In this study, we hypothesized that there is differential retrograde signaling occurring between the Stimulator of Interferon Genes (STING) pathway and H versus K mtDNA haplogroups Results showed that K cybrids exhibit increased levels of cytoplasmic mtDNA fragments After STING Knock-Down, H cybrids had lower expression levels for EGFR, BRCA1, DNMT3A, DNMT3B, HDAC1, and IFNα genes, but upregulated DNMT3A compared to control H cybrids The STING-KD K cybrids showed downregulation of EGFR, DNMT3A, HDAC1, HCAD9, CFH, and CHI, along with upregulation of DNMT1 and IL-6 compared to control K cybrids Since all cybrids have identical nuclei, the STING DNA sensor system interacts differently with K haplogroup mtDNA compared to H mtDNA for genes related to cancer (EGFR, BRCA1), methylation (DNMT1, DNMT3A, DNMT3B), acetylation (HDAC1, HDCA9), complement (CFH, CHI) and inflammation (IFNα, IL-6) In summary, in non-pathologic conditions, (a) STING is an important retrograde signaling mechanism(s) and (b) cybrids possessing Ashkenazi Jewish mtDNA (K haplogroup) interact with the STING complex differently compared to H cybrids which affects various disease-related pathways

Single Mutations Reshape the Structural Correlation Network of the DMXAA–Human STING Complex B

Abstract: Subtle changes in protein sequences are able to alter ligand–protein interactions. Unraveling the mechanism of such phenomena is important for understanding ligand–protein interactions, including the DMXAA–STING interaction. DMXAA specifically binds to mouse STING instead of human STING. However, the S162A mutation and a newly discovered E260I mutation endow human STINGᴬQ with DMXAA sensitivity. Through molecular dynamics simulations, we revealed how these single mutations alter the DMXAA–STING interaction. Compared to mutated systems, structural correlations in the interaction of STINGᴬQ with DMXAA are stronger, and the correlations are cross-protomers in the dimeric protein. Analyses on correlation coefficients lead to the identification of two key interactions that mediate the strong cross-protomer correlation in the DMXAA–STINGᴬQ interaction network: DMXAA–267T–162S* and 238R–260E*. These two interactions are partially and totally interrupted by the S162A and E260I mutations, respectively. Moreover, a smaller number of water molecules are displaced upon DMXAA binding to STINGᴬQ than that on binding to its mutants, leading to a larger entropic penalty for the former. Considering the sensitivity of STINGᴬQ and two of its mutants to DMXAA, a strong structural correlation appears to discourage DMXAA–STING binding. Such an observation suggests that DMXAA derivatives, which are deprived of hydrogen-bond interaction with both 162S* and 267T, are potential agonists of human STING.