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1.
J Am Chem Soc ; 146(19): 13488-13498, 2024 May 15.
Article in English | MEDLINE | ID: mdl-38709095

ABSTRACT

Self-assembling peptides represent a captivating area of study in nanotechnology and biomaterials. This interest is largely driven by their unique properties and the vast application potential across various fields such as catalytic functions. However, design complexities, including high-dimensional sequence space and structural diversity, pose significant challenges in the study of such systems. In this work, we explored the possibility of self-assembled peptides to catalyze the hydrolysis of hydrosilane for hydrogen production using ab initio calculations and carried out wet-lab experiments to confirm the feasibility of these catalytic reactions under ambient conditions. Further, we delved into the nuanced interplay between sequence, structural conformation, and catalytic activity by combining modeling with experimental techniques such as transmission electron microscopy and nuclear magnetic resonance and proposed a dual mode of the microstructure of the catalytic center. Our results reveal that although research in this area is still at an early stage, the development of self-assembled peptide catalysts for hydrogen production has the potential to provide a more sustainable and efficient alternative to conventional hydrogen production methods. In addition, this work also demonstrates that a computation-driven rational design supplemented by experimental validation is an effective protocol for conducting research on functional self-assembled peptides.


Subject(s)
Hydrogen , Peptides , Hydrogen/chemistry , Catalysis , Peptides/chemistry , Models, Molecular , Hydrolysis
2.
Nano Lett ; 24(6): 1843-1850, 2024 Feb 14.
Article in English | MEDLINE | ID: mdl-38316029

ABSTRACT

The penetrating growth of Li into the inorganic solid-state electrolyte (SSE) is one key factor limiting its practical application. Research to understand the underlying mechanism of Li penetration has been ongoing for years and is continuing. Here, we report an in situ scanning electron microscopy methodology to investigate the dynamic behaviors of isolated Li filaments in the garnet SSE under practical cycling conditions. We find that the filaments tend to grow in the SSE, while surprisingly, those filaments can self-dissolve with a decrease in the current density without a reversal of the current direction. We further build a coupled electro-chemo-mechanical model to assess the interplay between electrochemistry and mechanics during the dynamic evolution of filaments. We reveal that filament growth is strongly regulated by the competition between the electrochemical driving force and mechanical resistive force. The numerical results provide rational guidance for the design of solid-state batteries with excellent properties.

3.
J Helminthol ; 97: e101, 2023 Dec 21.
Article in English | MEDLINE | ID: mdl-38124668

ABSTRACT

Human cystic echinococcosis (CE) is a zoonotic disorder triggered by the larval stage of Echinococcus granulosus (E. granulosus) and predominantly occurred in the liver and lungs. The M2 macrophage level is considerably elevated among the liver of patients with hepatic CE and performs an integral function in liver fibrosis. However, the mechanism of CE inducing polarisation of macrophage to an M2 phenotype is unknown. In this study, macrophage was treated with E. granulosus cyst fluid (EgCF) to explore the mechanism of macrophage polarisation. Consequently, the expression of the M2 macrophage and production of anti-inflammatory cytokines increased after 48 h treatment by EgCF. In addition, EgCF promoted polarisation of macrophage to an M2 phenotype by inhibiting the expression of transcriptional factor hypoxia-inducible factor 1-alpha (HIF-1α), which increased the expression of glycolysis-associated genes, including hexokinase 2 (HK2) and pyruvate kinase 2 (PKM2). The HIF-1α agonist ML228 also inhibited the induction of macrophage to an M2 phenotype by EgCF in vitro. Our findings indicate that E. granulosus inhibits glycolysis by suppressing the expression of HIF-1α.


Subject(s)
Echinococcosis , Echinococcus granulosus , Humans , Animals , Cyst Fluid , Echinococcus granulosus/genetics , Macrophages , Lung
4.
Clin Immunol ; 256: 109774, 2023 11.
Article in English | MEDLINE | ID: mdl-37774907

ABSTRACT

Tumour-derived exosomes (TDEs) play an important role in tumourigenesis and progression by regulating components in the tumour microenvironment (TME), however, the role of TDE-related immune genes in hepatocellular carcinoma is not fully known. We systematically analysed TDE genes from ExoCarta and immune genes from Immport,Machine learning ultimately identified eight TDE-related prognostic immune genes and used them as the basis for constructing a risk model, which was constructed to better predict patients with hepatocellular carcinoma (HCC) compared with published prognostic models. There were significant differences between the high and low risk groups in terms of biological functioning. Low-risk group were more sensitive to immunotherapy, the sensitivity to oxaliplatin and cisplatin differed between the high- and low-risk groups, and knockout of the core gene RAC1 limited the malignant biological behaviour of hepatocellular carcinoma cells. In conclusion, TIRGs are effective in predicting the prognosis of patients with hepatocellular carcinoma and provide a new perspective on immunotherapy and chemotherapy for patients.


Subject(s)
Carcinoma, Hepatocellular , Exosomes , Liver Neoplasms , Humans , Carcinoma, Hepatocellular/genetics , Exosomes/genetics , Liver Neoplasms/genetics , Cell Line , Cell Transformation, Neoplastic , Tumor Microenvironment/genetics , Prognosis
5.
Cell Res ; 33(11): 851-866, 2023 11.
Article in English | MEDLINE | ID: mdl-37580406

ABSTRACT

Ultra-stable fibrous structure is a hallmark of amyloids. In contrast to canonical disease-related amyloids, emerging research indicates that a significant number of cellular amyloids, termed 'functional amyloids', contribute to signal transduction as temporal signaling hubs in humans. However, it is unclear how these functional amyloids are effectively disassembled to terminate signal transduction. RHIM motif-containing amyloids, the largest functional amyloid family discovered thus far, play an important role in mediating necroptosis signal transduction in mammalian cells. Here, we identify heat shock protein family A member 8 (HSPA8) as a new type of enzyme - which we name as 'amyloidase' - that directly disassembles RHIM-amyloids to inhibit necroptosis signaling in cells and mice. Different from its role in chaperone-mediated autophagy where it selects substrates containing a KFERQ-like motif, HSPA8 specifically recognizes RHIM-containing proteins through a hydrophobic hexapeptide motif N(X1)φ(X3). The SBD domain of HSPA8 interacts with RHIM-containing proteins, preventing proximate RHIM monomers from stacking into functional fibrils; furthermore, with the NBD domain supplying energy via ATP hydrolysis, HSPA8 breaks down pre-formed RHIM-amyloids into non-functional monomers. Notably, HSPA8's amyloidase activity in disassembling functional RHIM-amyloids does not require its co-chaperone system. Using this amyloidase activity, HSPA8 reverses the initiator RHIM-amyloids (formed by RIP1, ZBP1, and TRIF) to prevent necroptosis initiation, and reverses RIP3-amyloid to prevent necroptosis execution, thus eliminating multi-level RHIM-amyloids to effectively prevent spontaneous necroptosis activation. The discovery that HSPA8 acts as an amyloidase dismantling functional amyloids provides a fundamental understanding of the reversibility nature of functional amyloids, a property distinguishing them from disease-related amyloids that are unbreakable in vivo.


Subject(s)
Amyloid , Necroptosis , Animals , Humans , Mice , HSC70 Heat-Shock Proteins/metabolism , Mammals , Protein Binding , Receptor-Interacting Protein Serine-Threonine Kinases/metabolism , Signal Transduction
6.
Front Immunol ; 14: 1169256, 2023.
Article in English | MEDLINE | ID: mdl-37275878

ABSTRACT

Background: Hepatocellular carcinoma (HCC) is a leading cause of cancer-related deaths worldwide. Lysosomes are organelles that play an important role in cancer progression by breaking down biomolecules. However, the molecular mechanisms of lysosome-related genes in HCC are not fully understood. Methods: We downloaded HCC datasets from TCGA and GEO as well as lysosome-related gene sets from AIMGO. After univariate Cox screening of the set of lysosome-associated genes differentially expressed in HCC and normal tissues, risk models were built by machine learning. Model effects were assessed using the concordance index (C-index), Kaplan-Meier (K-M) and receiver operating characteristic curves (ROC). Additionally, we explored the biological function and immune microenvironment between the high- and low-risk groups, and analyzed the response of the high- and low-risk groups to immunotherapy responsiveness and chemotherapeutic agents. Finally, we explored the function of a key gene (RAMP3) at the cellular level. Results: Univariate Cox yielded 46 differentially and prognostically significant lysosome-related genes, and risk models were constructed using eight genes (RAMP3, GPLD1, FABP5, CD68, CSPG4, SORT1, CSPG5, CSF3R) derived from machine learning. The risk model was a better predictor of clinical outcomes, with the higher risk group having worse clinical outcomes. There were significant differences in biological function, immune microenvironment, and responsiveness to immunotherapy and drug sensitivity between the high and low-risk groups. Finally, we found that RAMP3 inhibited the proliferation, migration, and invasion of HCC cells and correlated with the sensitivity of HCC cells to Idarubicin. Conclusion: Lysosome-associated gene risk models built by machine learning can effectively predict patient prognosis and offer new prospects for chemotherapy and immunotherapy in HCC. In addition, cellular-level experiments suggest that RAMP3 may be a new target for the treatment of HCC.


Subject(s)
Carcinoma, Hepatocellular , Liver Neoplasms , Humans , Carcinoma, Hepatocellular/genetics , Prognosis , Liver Neoplasms/genetics , Lysosomes , Immunotherapy , Tumor Microenvironment/genetics , Fatty Acid-Binding Proteins
7.
Front Physiol ; 14: 1178589, 2023.
Article in English | MEDLINE | ID: mdl-37082235

ABSTRACT

[This corrects the article DOI: 10.3389/fphys.2022.1063970.].

8.
Structure ; 31(3): 230-243, 2023 03 02.
Article in English | MEDLINE | ID: mdl-36750098

ABSTRACT

Amyloids have special structural properties and are involved in many aspects of biological function. In particular, amyloids are the cause or hallmarks of a group of notorious and incurable neurodegenerative diseases. The extraordinary high molecular weight and aggregation states of amyloids have posed a challenge for researchers studying them. Solid-state NMR (SSNMR) has been extensively applied to study the structures and dynamics of amyloids for the past 20 or more years and brought us tremendous progress in understanding their structure and related diseases. These studies, at the same time, helped to push SSNMR technical developments in sensitivity and resolution. In this review, some interesting research studies and important technical developments are highlighted to give the reader an overview of the current state of this field.


Subject(s)
Amyloid , Amyloid/chemistry , Magnetic Resonance Spectroscopy
9.
ACS Appl Mater Interfaces ; 15(5): 6666-6675, 2023 Feb 08.
Article in English | MEDLINE | ID: mdl-36705679

ABSTRACT

Lithium (Li) metal is a promising candidate for next-generation anode materials with high energy densities. However, Li dissolution/deposition processes are limited at the upper surface in contact with the electrolyte, which brings a locally high current density and then results in dendritic Li growth. This restraint of the local surface reaction during cycling has not been solved by commonly used modification strategies. In this study, a three-dimensional (3D) Li+ conductive skeleton is activated from atomic layer deposition (ALD) coating Li3PO4 (LPO) on the surface of the Ni foam (LPNF). Then, the skeleton is efficiently constructed in the Li metal anode by the lower-temperature Li infusion. Ionic conductor LPO layers and electronic conductor Ni fibers supply charge transport channels between the electrolyte and the internal Li. The mixed conductive network realizes holistic charge transfer, which is proved by in situ scanning electron microscopy experiments. In virtue of dispersive dissolution/deposition and optimized electrochemical kinetics brought by a Li+ conductive network, the composited Li electrode presents an excellent symmetric battery cycling stability (over 1200 h) and enhanced rate performances (stable cycling even at 10.0 mA cm-2). When matching with a LiCoO2 (LCO) cathode, LCO||Li@LPNF full batteries exhibit a capacity retention of 80.8% over 250 cycles. During cycling, there was no evidence of dendrite growth and the remaining Li in the composited anode showed a smooth, compact, and well-combined condition with LPNF. Through constructing a 3D Li+ conductive network, the composited Li metal anode breaks through the limit of the local surface reaction; this work proposes a novel insight of realizing holistic charging/discharging for the dendrite-free Li metal anode.

10.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-965595

ABSTRACT

@#[摘 要] 目的:探讨肿瘤浸润CD8+ T细胞表达CD39的可能机制。方法:通过TCGA数据库的肺腺癌(LUAD)组织及正常肺组织转录组数据分析CD39在LUAD组织和正常肺组织中的表达差异及其对患者预后的影响,分析CD39表达与T细胞浸润、激活的关系。用小鼠LUAD Lewis细胞建立小鼠皮下移植瘤模型,FCM检测淋巴结、脾脏以及移植瘤组织中CD8+ CD39+ T细胞。收集Lewis细胞培养上清液作为条件培养基(CCM),免疫磁珠法(MACS)分选CD8+ T细胞、CD11b+细胞;在培养基中分别加入CCM、IL-6和采取非接触或接触培养方式进行培养,探索CD8+ T细胞表达CD39的可能机制。结果:CD39在LUAD组织中呈低表达(P<0.01),其表达水平与LUAD患者OS、T细胞浸润和激活水平均呈正相关(P<0.05或P<0.001)。FCM检测结果显示,在移植瘤组织中CD8+CD39+ T细胞的比例明显高于淋巴结及脾脏(P<0.01);CCM及IL-6不能直接诱导CD8+ T细胞表达CD39,非接触共培养CD11b+细胞与CD8+T细胞也不能诱导CD8+ T细胞表达CD39,CD11b+细胞与CD8+ T细胞直接接触共培养可诱导CD8+ T细胞表达CD39(P<0.01)。结论:CD11b+细胞通过直接接触方式诱导肿瘤浸润CD8+ T细胞表达CD39,CD39可能是LUAD特异性CD8+ T细胞的分子标志。

11.
Int J Mol Sci ; 23(23)2022 Dec 03.
Article in English | MEDLINE | ID: mdl-36499553

ABSTRACT

The liquid-liquid phase separation (LLPS) of proteins has been found ubiquitously in eukaryotic cells, and is critical in the control of many biological processes by forming a temporary condensed phase with different bimolecular components. TDP-43 is recruited to stress granules in cells and is the main component of TDP-43 granules and proteinaceous amyloid inclusions in patients with amyotrophic lateral sclerosis (ALS). TDP-43 low complexity domain (LCD) is able to de-mix in solution, forming the protein condensed droplets, and amyloid aggregates would form from the droplets after incubation. The molecular interactions regulating TDP-43 LCD LLPS were investigated at the protein fusion equilibrium stage, when the droplets stopped growing after incubation. We found the molecules in the droplet were still liquid-like, but with enhanced intermolecular helix-helix interactions. The protein would only start to aggregate after a lag time and aggregate slower than at the condition when the protein does not phase separately into the droplets, or the molecules have a reduced intermolecular helix-helix interaction. In the protein condensed droplets, a structural transition intermediate toward protein aggregation was discovered involving a decrease in the intermolecular helix-helix interaction and a reduction in the helicity. Our results therefore indicate that different intermolecular interactions drive LLPS and fibril formation. The discovery that TDP-43 LCD aggregation was faster through the pathway without the first protein phase separation supports that LLPS and the intermolecular helical interaction could help maintain the stability of TDP-43 LCD.


Subject(s)
Amyotrophic Lateral Sclerosis , Humans , Amyloid , Amyloidogenic Proteins , Amyotrophic Lateral Sclerosis/metabolism , Protein Aggregates
12.
JBMR Plus ; 6(10): e10662, 2022 Oct.
Article in English | MEDLINE | ID: mdl-36248276

ABSTRACT

Solid-state nuclear magnetic resonance (SSNMR), a technique capable of studying solid or semisolid biological samples, was first applied to study the cell differentiation and mineralization using the whole-cell sample. Mesenchymal stromal cells (MSCs) with multipotent differentiation capacity were induced to differentiate into osteoblasts. The whole differentiation process, osteoblast mineralization and the mineral maturation, was investigated using SSNMR, providing intact, atomic level information on the cellular mineral structural transformation. Our research indicated the extent of osteoblast mineralization could vary significantly for different cell populations whereas the difference was not easily shown by other means of characterization. The SSNMR spectra revealed hydroxylapatite (or hydroxyapatite [HAP]) formation around 2 to 4 weeks after osteogenic induction for MSCs with a high differentiation potency. The early mineral phase deposit before HAP formation contained a high amount of HPO4 2-. The structures of minerals in the extracellular matrix (ECM) of osteoblasts could evolve for a period of time, even after the incubation of cells has been stopped. This observation was only possible by studying the sample in an intact state, where ECM was not disturbed. These findings improved our understanding of MSCs, which had wide applications in bone regeneration and tissue engineering. Meanwhile, this work demonstrated the advantage of studying these cellular systems as a whole without any mineral extraction, which had been largely overlooked. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

13.
Front Physiol ; 13: 1063970, 2022.
Article in English | MEDLINE | ID: mdl-36589425

ABSTRACT

Phosphorylation of serine residues has been recognized as a pivotal event in the evolution of mineralized tissues in many biological systems. During enamel development, the extracellular matrix protein amelogenin is most abundant and appears to be critical to the extreme high aspect ratios (length:width) of apatite mineral fibers reaching several millimeters in larger mammalian teeth. A 14-residue peptide (14P2, residues Gly8 to Thr21) was previously identified as a key sequence mediating amelogenin assembly formation, the domain also contains the native single phosphoserine residue (Ser16) of the full-length amelogenin. In this research, 14P2 and its phosphorylated form (p14P2) were investigated at pH 6.0 with various calcium and phosphate ion concentrations, indicating that both peptides could self-assemble into amyloid-like conformation but with differences in structural details. With calcium, the distance between 31P within the p14P2 self-assemblies is averaged to be 4.4 ± 0.2Å, determined by solid-state NMR 31P PITHIRDS-CT experiments. Combining with other experimental results, solid-state Nuclear Magnetic Resonance (SSNMR) suggests that the p14P2 self-assemblies are in parallel in-register ß-sheet conformation and divalent calcium ions most likely connect two adjacent peptide chains by binding to the phosphate group of Ser16 and the carboxylate of Glu18 side-chain. This study on the interactions between calcium ions and amelogenin-derived peptides provides insights on how amelogenin may self-assemble in the presence of calcium ions in early enamel development.

14.
Life (Basel) ; 11(9)2021 Aug 31.
Article in English | MEDLINE | ID: mdl-34575058

ABSTRACT

The succinate-acetate permease (SatP) is an anion channel with six transmembrane domains. It forms different oligomers, especially hexamers in the detergent as well as in the membrane. Solid-state NMR studies of SatP were carried out successfully on SatP complexes by reconstructing the protein into liposomes or retaining the protein in the native membrane of E. coli., where it was expressed. The comparison of 13C-13C 2D correlation spectra between the two samples showed great similarity, opening the possibility to further study the acetate transport mechanism of SatP in its native membrane environment. Solid-state NMR studies also revealed small chemical shift differences of SatP in the two different membrane systems, indicating the importance of the lipid environment in determining the membrane protein structures and dynamics. Combining different 2D SSNMR spectra, chemical shift assignments were made on some sites, consistent with the helical structures in the transmembrane domains. In the end, we pointed out the limitation in the sensitivity for membrane proteins with such a size, and also indicated possible ways to overcome it.

15.
PLoS Biol ; 19(6): e3001297, 2021 06.
Article in English | MEDLINE | ID: mdl-34111112

ABSTRACT

Recent studies have shown that long noncoding RNAs (lncRNAs) are critical regulators in the central nervous system (CNS). However, their roles in the cerebellum are currently unclear. In this work, we identified the isoform 204 of lncRNA Gm2694 (designated as lncRNA-Promoting Methylation (lncRNA-PM)) is highly expressed in the cerebellum and derived from the antisense strand of the upstream region of Cerebellin-1 (Cbln1), a well-known critical cerebellar synaptic organizer. LncRNA-PM exhibits similar spatiotemporal expression pattern as Cbln1 in the postnatal mouse cerebellum and activates the transcription of Cbln1 through Pax6/Mll1-mediated H3K4me3. In mouse cerebellum, lncRNA-PM, Pax6/Mll1, and H3K4me3 are all associated with the regulatory regions of Cbln1. Knockdown of lncRNA-PM in cerebellum causes deficiencies in Cbln1 expression, cerebellar synaptic integrity, and motor function. Together, our work reveals an lncRNA-mediated transcriptional activation of Cbln1 through Pax6-Mll1-H3K4me3 and provides novel insights of the essential roles of lncRNA in the cerebellum.


Subject(s)
Histone-Lysine N-Methyltransferase/metabolism , Histones/metabolism , Myeloid-Lymphoid Leukemia Protein/metabolism , Nerve Tissue Proteins/metabolism , PAX6 Transcription Factor/metabolism , Protein Precursors/metabolism , RNA, Long Noncoding/metabolism , Synapses/metabolism , Alternative Splicing/genetics , Cerebellum/metabolism , Gene Expression Regulation , HEK293 Cells , Histone-Lysine N-Methyltransferase/genetics , Humans , Motor Activity , Myeloid-Lymphoid Leukemia Protein/genetics , Neurons/metabolism , Presynaptic Terminals/metabolism , Protein Isoforms/genetics , Protein Isoforms/metabolism , RNA, Long Noncoding/genetics , Transcriptional Activation/genetics
16.
Proc Natl Acad Sci U S A ; 118(14)2021 04 06.
Article in English | MEDLINE | ID: mdl-33790016

ABSTRACT

Receptor-interacting protein kinases 3 (RIPK3), a central node in necroptosis, polymerizes in response to the upstream signals and then activates its downstream mediator to induce cell death. The active polymeric form of RIPK3 has been indicated as the form of amyloid fibrils assembled via its RIP homotypic interaction motif (RHIM). In this study, we combine cryogenic electron microscopy and solid-state NMR to determine the amyloid fibril structure of RIPK3 RHIM-containing C-terminal domain (CTD). The structure reveals a single protofilament composed of the RHIM domain. RHIM forms three ß-strands (referred to as strands 1 through 3) folding into an S shape, a distinct fold from that in complex with RIPK1. The consensus tetrapeptide VQVG of RHIM forms strand 2, which zips up strands 1 and 3 via heterozipper-like interfaces. Notably, the RIPK3-CTD fibril, as a physiological fibril, exhibits distinctive assembly compared with pathological fibrils. It has an exceptionally small fibril core and twists in both handedness with the smallest pitch known so far. These traits may contribute to a favorable spatial arrangement of RIPK3 kinase domain for efficient phosphorylation.


Subject(s)
Amyloid/chemistry , Receptor-Interacting Protein Serine-Threonine Kinases/chemistry , Amino Acid Motifs , Amyloid/metabolism , Cryoelectron Microscopy , Humans , Necroptosis , Phosphorylation , Protein Domains , Receptor-Interacting Protein Serine-Threonine Kinases/metabolism
17.
Nat Commun ; 12(1): 1627, 2021 03 12.
Article in English | MEDLINE | ID: mdl-33712586

ABSTRACT

RIPK3 amyloid complex plays crucial roles during TNF-induced necroptosis and in response to immune defense in both human and mouse. Here, we have structurally characterized mouse RIPK3 homogeneous self-assembly using solid-state NMR, revealing a well-ordered N-shaped amyloid core structure featured with 3 parallel in-register ß-sheets. This structure differs from previously published human RIPK1/RIPK3 hetero-amyloid complex structure, which adopted a serpentine fold. Functional studies indicate both RIPK1-RIPK3 binding and RIPK3 amyloid formation are essential but not sufficient for TNF-induced necroptosis. The structural integrity of RIPK3 fibril with three ß-strands is necessary for signaling. Molecular dynamics simulations with a mouse RIPK1/RIPK3 model indicate that the hetero-amyloid is less stable when adopting the RIPK3 fibril conformation, suggesting a structural transformation of RIPK3 from RIPK1-RIPK3 binding to RIPK3 amyloid formation. This structural transformation would provide the missing link connecting RIPK1-RIPK3 binding to RIPK3 homo-oligomer formation in the signal transduction.


Subject(s)
Amyloid/metabolism , Amyloid/ultrastructure , Necroptosis/physiology , Receptor-Interacting Protein Serine-Threonine Kinases/chemistry , Receptor-Interacting Protein Serine-Threonine Kinases/metabolism , Animals , Benzothiazoles , Cell Survival , Drosophila , Herpesviridae , Humans , Mice , Molecular Dynamics Simulation , Necroptosis/genetics , Protein Conformation , Rats , Receptor-Interacting Protein Serine-Threonine Kinases/genetics , Sequence Alignment , Sequence Analysis, Protein , Signal Transduction
18.
Cell Death Differ ; 28(1): 251-266, 2021 01.
Article in English | MEDLINE | ID: mdl-32737444

ABSTRACT

Necroptosis is mediated by signaling complexes called necrosomes, which contain receptor-interacting protein 3 (RIP3) and upstream effectors, such as RIP1. In necrosomes, the RIP homotypic interaction motif (RHIM) of RIP3 and RIP1 forms amyloidal complex. But how the amyloidal necrosomes control RIP3 activation and cell necroptosis has not been determined. Here, we showed that RIP3 amyloid fibrils could further assemble into large fibrillar networks which presents as cellular puncta during necroptosis. A viral RHIM-containing necroptosis inhibitor M45 could form heteroamyloid with RIP3 in cells and prevent RIP3 puncta formation and cell necroptosis. We characterized mutual antagonism between RIP3-RHIM and M45-RHIM in necroptosis regulation, which was caused by distinct inter-filament interactions in RIP3, M45 amyloids revealed with atomic force microscopy. Moreover, double mutations Asn464 and Met468 in RIP3-RHIM to Asp disrupted RIP3 kinase-dependent necroptosis. While the mutant RIP3(N464D/M468D) could form amyloid as wild type upon necroptosis induction. Based on these results, we propose that RIP3 amyloid formation is required but not sufficient in necroptosis signaling, the ordered inter-filament assembly of RIP3 is critical in RIP3 amyloid mediated kinase activation and cell necroptosis.


Subject(s)
Necroptosis/physiology , Necrosis/enzymology , Receptor-Interacting Protein Serine-Threonine Kinases/metabolism , Amyloid/metabolism , Animals , Cell Line, Tumor , Humans , Mice , Mutation , Necrosis/genetics , Phosphorylation , Receptor-Interacting Protein Serine-Threonine Kinases/genetics
19.
Cell Mol Immunol ; 18(3): 675-685, 2021 03.
Article in English | MEDLINE | ID: mdl-32235917

ABSTRACT

Induction of broadly neutralizing monoclonal antibodies (bNAbs) that bind to the viral envelope glycoproteins is a major goal of hepatitis C virus (HCV) vaccine research. The study of bNAbs arising in natural infection is essential in this endeavor. We generated a human antibody, 8D6, recognizing the E2 protein of HCV isolated from a chronic hepatitis C patient. This antibody shows broadly neutralizing activity, which covers a pan-genotypic panel of cell culture-derived HCV virions (HCVcc). Functional and epitope analyses demonstrated that 8D6 can block the interaction between E2 and CD81 by targeting a highly conserved epitope on E2. We describe how the 8D6 lineage evolved via somatic hypermutation to achieve broad neutralization. We found that the V(D)J recombination-generated junctional and somatic hypermutation-induced disulfide bridge (C-C) motif in the CDRH3 is critical for the broad neutralization and binding activity of 8D6. This motif is conserved among a series of broadly neutralizing HCV antibodies, indicating a common binding model. Next, the 8D6 inferred germline (iGL) was reconstructed and tested for its binding affinity and neutralization activity. Interestingly, 8D6 iGL-mediated relatively strong inhibition of the 1b genotype PR79L9 strain, suggesting that PR79L9 may serve as a potential natural viral strain that provides E2 sequences that induce bNAbs. Overall, our detailed epitope mapping and genetic studies of the HCV E2-specific mAb 8D6 have allowed for further refinement of antigenic sites on E2 and reveal a new mechanism to generate a functional CDRH3, while its iGL can serve as a probe to identify potential HCV vaccine strains.


Subject(s)
Broadly Neutralizing Antibodies/pharmacology , Complementarity Determining Regions/genetics , Epitopes/immunology , Hepacivirus/immunology , Hepatitis C Antibodies/immunology , Hepatitis C/prevention & control , Viral Envelope Proteins/immunology , Antibodies, Monoclonal/pharmacology , Complementarity Determining Regions/immunology , Epitope Mapping , Hepatitis C/genetics , Hepatitis C/immunology , Hepatitis C/virology , Humans , Immunoglobulin Heavy Chains , Mutation , Protein Interaction Domains and Motifs
20.
iScience ; 23(11): 101708, 2020 Nov 20.
Article in English | MEDLINE | ID: mdl-33241194

ABSTRACT

AMFR/gp78 and USP13 are a pair of ubiquitin ligase and deubiquitinase that ensure the accuracy of endoplasmic reticulum-associated degradation (ERAD). Depletion of USP13 leads to caspase activation and cleavage of the ERAD chaperone BAG6, which is reversed by knockdown of AMFR. However, the mechanism and physiological relevance of this regulation are still unclear. Here, by using the NEDDylator system, we screened out TXN as a substrate of AMFR and USP13 and showed its involvement in regulating CASP3 activation and BAG6 cleavage. Furthermore, we showed that the cleaved N-terminal BAG6 is located in the cytosol and interacts with both LC3B-I and unprocessed form of LC3B (Pro-LC3B) through the LIR1 motif to suppress autophagy. An NMR approach verified the direct interaction between BAG6 LIR1 and LC3B-I or Pro-LC3B. Collectively, our findings uncover a mechanism that converts BAG6 from an ERAD regulator to an autophagy tuner and apoptosis inducer during ER stress.

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