1.Structural and biochemical studies of RIG-I antiviral signaling.
Miao FENG ; Zhanyu DING ; Liang XU ; Liangliang KONG ; Wenjia WANG ; Shi JIAO ; Zhubing SHI ; Mark I GREENE ; Yao CONG ; Zhaocai ZHOU
Protein & Cell 2013;4(2):142-154
Retinoic acid-inducible gene I (RIG-I) is an important pattern recognition receptor that detects viral RNA and triggers the production of type-I interferons through the downstream adaptor MAVS (also called IPS-1, CARDIF, or VISA). A series of structural studies have elaborated some of the mechanisms of dsRNA recognition and activation of RIG-I. Recent studies have proposed that K63-linked ubiquitination of, or unanchored K63-linked polyubiquitin binding to RIG-I positively regulates MAVS-mediated antiviral signaling. Conversely phosphorylation of RIG-I appears to play an inhibitory role in controlling RIG-I antiviral signal transduction. Here we performed a combined structural and biochemical study to further define the regulatory features of RIG-I signaling. ATP and dsRNA binding triggered dimerization of RIG-I with conformational rearrangements of the tandem CARD domains. Full length RIG-I appeared to form a complex with dsRNA in a 2:2 molar ratio. Compared with the previously reported crystal structures of RIG-I in inactive state, our electron microscopic structure of full length RIG-I in complex with blunt-ended dsRNA, for the first time, revealed an exposed active conformation of the CARD domains. Moreover, we found that purified recombinant RIG-I proteins could bind to the CARD domain of MAVS independently of dsRNA, while S8E and T170E phosphorylation-mimicking mutants of RIG-I were defective in binding E3 ligase TRIM25, unanchored K63-linked polyubiquitin, and MAVS regardless of dsRNA. These findings suggested that phosphorylation of RIG inhibited downstream signaling by impairing RIG-I binding with polyubiquitin and its interaction with MAVS.
Adaptor Proteins, Signal Transducing
;
metabolism
;
Adenosine Triphosphate
;
metabolism
;
DEAD Box Protein 58
;
DEAD-box RNA Helicases
;
chemistry
;
genetics
;
metabolism
;
Dimerization
;
Humans
;
Mutagenesis, Site-Directed
;
Phosphorylation
;
Polyubiquitin
;
metabolism
;
Protein Binding
;
Protein Structure, Tertiary
;
RNA, Double-Stranded
;
metabolism
;
Recombinant Proteins
;
biosynthesis
;
chemistry
;
genetics
;
Signal Transduction
;
Transcription Factors
;
metabolism
;
Tripartite Motif Proteins
;
Ubiquitin-Protein Ligases
;
metabolism
;
Ubiquitination
2.A YAP/TAZ-CD54 axis is required for CXCR2-CD44- tumor-specific neutrophils to suppress gastric cancer.
Pingping NIE ; Weihong ZHANG ; Yan MENG ; Moubin LIN ; Fenghua GUO ; Hui ZHANG ; Zhenzhu TONG ; Meng WANG ; Fan CHEN ; Liwei AN ; Yang TANG ; Yi HAN ; Ruixian YU ; Wenjia WANG ; Yuanzhi XU ; Linxin WEI ; Zhaocai ZHOU ; Shi JIAO
Protein & Cell 2023;14(7):513-531
As an important part of tumor microenvironment, neutrophils are poorly understood due to their spatiotemporal heterogeneity in tumorigenesis. Here we defined, at single-cell resolution, CD44-CXCR2- neutrophils as tumor-specific neutrophils (tsNeus) in both mouse and human gastric cancer (GC). We uncovered a Hippo regulon in neutrophils with unique YAP signature genes (e.g., ICAM1, CD14, EGR1) distinct from those identified in epithelial and/or cancer cells. Importantly, knockout of YAP/TAZ in neutrophils impaired their differentiation into CD54+ tsNeus and reduced their antitumor activity, leading to accelerated GC progression. Moreover, the relative amounts of CD54+ tsNeus were found to be negatively associated with GC progression and positively associated with patient survival. Interestingly, GC patients receiving neoadjuvant chemotherapy had increased numbers of CD54+ tsNeus. Furthermore, pharmacologically enhancing YAP activity selectively activated neutrophils to suppress refractory GC, with no significant inflammation-related side effects. Thus, our work characterized tumor-specific neutrophils in GC and revealed an essential role of YAP/TAZ-CD54 axis in tsNeus, opening a new possibility to develop neutrophil-based antitumor therapeutics.
Humans
;
Animals
;
Mice
;
Adaptor Proteins, Signal Transducing/metabolism*
;
Transcription Factors/metabolism*
;
Stomach Neoplasms/pathology*
;
Neutrophils/pathology*
;
Signal Transduction/genetics*
;
YAP-Signaling Proteins
;
Tumor Microenvironment
;
Hyaluronan Receptors/genetics*