ABSTRACT
Z-DNA binding protein 1 (ZBP1) is a crucial player in the intracellular recognition of Z-form nucleic acids (Z-NAs) through its Zαß domain, initiating downstream interactions with RIPK1 and RIPK3 via RHIM domains. This engagement leads to the assembly of PANoptosomes, ultimately inducing programmed cell death to curb pathogen dissemination. How Zαß and RHIM domain cooperate to trigger Z-NAs recognition and signal transduction remains unclear. Here, we show that ZBP1 condensate formation facilitates Z-NAs binding and antiviral signal transduction. The ZBP1 Zαß dimerizes in a concentration-dependent manner, forming characteristic condensates in solutions evidenced by DLS and SAXS methods. ZBP1 exhibits a binding preference for 10-bp length CG (10CG) DNA and Z-RNA ligand, which in turn enhanced Zαß dimerization, expediting the formation of droplet condensates in vitro and amyloid-like puncta in cells. Subsequent investigations reveal that Zαß could form condensates with liquid-liquid phase separation property upon HSV and IAV infections, while full-length ZBP1 forms amyloid-like puncta with or without infections. Furthermore, ZBP1 RHIM domains show typical amyloidal fibril characterizations and cross-polymerize with RIPK1 depending on the core motif of 206IQIG209, while mutated ZBP1 could impede necroptosis and antiviral immunity in HT-29 cells. Thus, ZBP1 condensate formation facilitates the recognition of viral Z-NAs and activation of downstream signal transduction via synergic action of different domains, revealing its elaborated mechanism in innate immunity.
Subject(s)
RNA-Binding Proteins , Signal Transduction , Humans , RNA-Binding Proteins/metabolism , RNA-Binding Proteins/genetics , DNA, Z-Form/metabolism , DNA, Z-Form/chemistry , Protein Binding , Animals , Receptor-Interacting Protein Serine-Threonine Kinases/metabolism , Receptor-Interacting Protein Serine-Threonine Kinases/genetics , Protein MultimerizationABSTRACT
Gasdermin (GSDM)-mediated cell lytic death plays an essential role in immunity and tumorigenesis. Despite the association of gasdermin B (GSDMB) with the tumorigenesis of various cancers, whether GSDMB functions as a prognostic biomarker in renal cell carcinoma remains poorly understood. Here, we explored the potential immunological functions and the prognostic value of GSDMB across multiple tumors with The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases, including analyzing the relationship between GSDMB expression and prognosis, tumor-immune system interactions, immunomodulators, and immune cell infiltration of different tumors. Importantly, elevated expression of GSDMB is an essential factor for the poor prognosis of kidney renal clear cell carcinoma (KIRC) patients, suggesting that it might be helpful to predict a survival benefit from a clinical therapy regimen. Furthermore, GSDMB expression promoted the level of CD4+ T-cell infiltration of the tumors but is significantly negatively associated with immature dendritic cells (iDCs) in KIRC. Additionally, we identified TNFRSF25 and TNFSF14 as immunostimulators highly correlated with GSDMB expression. Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analyses showed that GSDMB and its interacting proteins might affect tumor growth through the serine metabolism pathway. Our current results demonstrate a promising therapeutic strategy targeting GSDMB and provide new insights into GSDMB as an immunological and prognostic biomarker for KIRC.
ABSTRACT
Gasdermin-D (GSDMD), the executioner of pyroptotic cell death when it is cleaved by inflammatory caspases, plays a crucial role in host defense and the response to danger signals. So far, there are no known mechanisms, other than cleavage, for regulating GSDMD. Here, we show that tripartite motif protein TRIM21 acts as a positive regulator of GSDMD-dependent pyroptosis. TRIM21 interacted with GSDMD via its PRY-SPRY domain, maintaining GSDMD stable expression in resting cells yet inducing the N-terminus of GSDMD (GSDMD-N) aggregation during pyroptosis. TRIM21-deficient cells displayed a reduced cell death in response to NLRP3 or NLRC4 inflammasome activation. Genetic ablation of TRIM21 in mice conferred protection from LPS-induced inflammation and dextran sulfate sodium-induced colitis. Therefore, TRIM21 plays an essential role in GSDMD-mediated pyroptosis and may be a viable target for controlling and treating inflammation-associated diseases.
Subject(s)
Intracellular Signaling Peptides and Proteins , Pyroptosis , Animals , Inflammasomes/metabolism , Inflammation , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Mice , Phosphate-Binding Proteins/genetics , Phosphate-Binding Proteins/metabolismABSTRACT
Serine/threonine-protein kinase-like protein ARABIDOPSIS CRINKLY4 (ACR4), a transmembrane protein of Arabidopsis thaliana, plays important roles in cell division and differentiation. Although accumulating studies shed light on the function of ACR4, the structure and catalytic mechanism of ACR4 remain to be elucidated. Here, we report the purification and enzymatic properties of the intracellular kinase domain (residues 464-799) of ACR4 (ACR4IKD). Through Ni-affinity chromatography and gel filter chromatography methods, we successfully obtain high-purity ACR4IKD protein from Escherichia coli. Dynamic light scattering and gel-filtration methods reveal that ACR4IKD distributes with high homogeneity and exists as a monomer in solution. In addition, the ACR4IKD protein has typical kinase activity with myelin basic protein (MBP) as the substrate. Our study may lay the foundation for structure determination of ACR4IKD and further functional research, for example, screening significant substrates of ACR4 in Arabidopsis thaliana.