多配体蛋白聚糖-4和新型金属蛋白酶-1在组织愈合过程中的作用

多配体蛋白聚糖-4是一种新发现的多肽,广泛存在于多种组织中,调控着多种生物学效应。含Ⅰ型血小板结合蛋白基序的解聚蛋白样金属蛋白酶(ADAMTS)-1是一种新型金属蛋白酶,广泛存在于哺乳动物和无脊椎动物体内,在保持凝血系统的稳态、器官生成、炎症和生育等方面起着重要的作用。二者均参与组织的创伤愈合过程,且ADAMTS-1特异性地作用于多配体蛋白聚糖-4,使其胞外区脱落。本文就多配体蛋白聚糖、ADAMTS-1、多配体蛋白聚糖-4与ADAMTS-1、多配体蛋白聚糖-4与牙周组织等研究进展作一综述,为探究牙周组织的损伤修复机制提供理论依据。     

Tryptophan 387 and 390 residues in ADAMTS13 are crucial to the ability of vascular tube formation and cell migration of endothelial cells

A disintegrin and metalloproteinase with thrombospondin motifs 13 (ADAMTS13) was mainly generated and secreted from endothelial cells (ECs). Our previous study showed that tryptophan (Trp) residues at 387 and 390 in ADAMTS13 are required for its secretion and enzymatic activity. However, the effects on its host cell as well as the potential mechanism have not been clear. The aim of the study was to examine the effects of Trp residues 387 and 390 of ADAMTS13 on the biological processes of ECs. Herein, Trp was substituted with alanine in ADAMTS13 to generate ADAMTS13 mutants at 387 (W387A), 390 (W390A), and double mutants at 387 and 390 (2WA), respectively. We found that substitution mutation impaired vascular endothelial growth factor (VEGF) secretion and the downstream JAK1/STAT3 activation, the binding ability to Von Willebrand factor, cell proliferation, migration, and vascular tube formation. Overall, our study concluded that Trp³⁸⁷ and Trp³⁹⁰ of ADAMTS13 play vital roles in the biological function of ECs.     

COVID-19 adenovirus vector vaccine induces higher interferon and pro-inflammatory responses than mRNA vaccines in human PBMCs,macrophages and moDCs

BackgroundDuring the COVID-19 pandemic multiple vaccines were rapidly developed and widely used throughout the world. At present there is very little information on COVID-19 vaccine interactions with primary human immune cells such as peripheral blood mononuclear cells (PBMCs), monocyte-derived macrophages and dendritic cells (moDCs).MethodsHuman PBMCs, macrophages and moDCs were stimulated with different COVID-19 vaccines, and the expression of interferon (IFN-λ1, IFN-α1), pro-inflammatory (IL-1β, IL-6, IL-8, IL-18, CXCL-4, CXCL-10, TNF-α) and Th1-type cytokine mRNAs (IL-2, IFN-γ) were analyzed by qPCR. In addition, the expression of vaccine induced spike (S) protein and antiviral molecules were studied in primary immune cells and in A549 lung epithelial cells.ResultsAdenovirus vector (Ad-vector) vaccine AZD1222 induced high levels of IFN-λ1, IFN-α1, CXCL-10, IL-6, and TNF-α mRNAs in PBMCs at early time points of stimulation while the expression of IFN-γ and IL-2 mRNA took place at later times. AZD1222 also induced IFN-λ1, CXCL-10 and IL-6 mRNA expression in monocyte-derived macrophages and DCs in a dose-dependent fashion. AZD1222 also activated the phosphorylation of IRF3 and induced MxA expression. BNT162b2 and mRNA-1273 mRNA vaccines failed to induce or induced very weak cytokine gene expression in all cell models. None of the vaccines enhanced the expression of CXCL-4. AZD1222 and mRNA-1273 vaccines induced high expression of S protein in all studied cells.ConclusionsAd-vector vaccine induces higher IFN and pro-inflammatory responses than the mRNA vaccines in human immune cells. This data shows that AZD1222 readily activates IFN and pro-inflammatory cytokine gene expression in PBMCs, macrophages and DCs, but fails to further enhance CXCL-4 mRNA expression.     

胶质母细胞瘤组织RBM8A表达与病人预后及替莫唑胺化疗敏感性的关系

目的 探讨胶质母细胞瘤（GBM）组织RNA结合基序8A（RBM8A）蛋白表达与病人预后及替莫唑胺（TMZ）化疗敏感性的关系。方法 选取2015年6月至2020年6月手术切除的GBM组织130例及颅脑损伤减压术中切取的非肿瘤脑组织20例（对照）,用免疫组化法检测组织RBM8A表达。术随访时间3~50个月,中位随访时间为12个月。结果 GBM组织RBM8A高表达率[86.15%（112/130）]明显高于对照组[20%（4/20）;P<0.05]。随访期间死亡98例,失访2例;多因素Cox回归分析显示,RBM8A高表达是GBM病人生存预后不良的独立危险因素（P<0.05）。生存曲线分析显示,RBM8A高表达GBM病人中位无复发生存时间和总生存时间均明显低于低表达病人（P<0.05）;RBM8A低表达GBM病人中,TMZ化疗病人无复发生存时间和总生存时间均明显高于未化疗病人（P<0.05）;TMZ化疗与RBM8A高表达GBM病人无复发生存时间和总生存时间无明显关系（P>0.05）。结论 GBM组织RBM8A呈高表达,与病人不良生存预后有关。检测RBM8A有助于评估GBM病人对TMZ化疗敏感性。     

A study on antigenicity and receptor-binding ability of fragment 450-650 of the spike protein of SARS coronavirus

The spike (S) protein of SARS coronavirus (SARS-CoV) is responsible for viral binding with ACE2 molecules. Its receptor-binding motif (S-RBM) is located between residues 424 and 494, which folds into 2 anti-parallel beta-sheets, beta5 and beta6. We have previously demonstrated that fragment 450-650 of the S protein (S450-650) is predominantly recognized by convalescent sera of SARS patients. The N-terminal 60 residues (450-510) of the S450-650 fragment covers the entire beta6 strand of S-RBM. In the present study, we demonstrate that patient sera predominantly recognized 2 linear epitopes outside the beta6 fragment, while the mouse antisera, induced by immunization of BALB/c mice with recombinant S450-650, mainly recognized the beta6 strand-containing region. Unlike patient sera, however, the mouse antisera were unable to inhibit the infectivity of S protein-expressing (SARS-CoV-S) pseudovirus. Fusion protein between green fluorescence protein (GFP) and S450-650 (S450-650-GFP) was able to stain Vero E6 cells and deletion of the beta6 fragment rendered the fusion product (S511-650-GFP) unable to do so. Similarly, recombinant S450-650, but not S511-650, was able to block the infection of Vero E6 cells by the SARS-CoV-S pseudovirus. Co-precipitation experiments confirmed that S450-650 was able to specifically bind with ACE2 molecules in lysate of Vero E6 cells. However, the ability of S450-510, either alone or in fusion with GFP, to bind with ACE2 was significantly poorer compared with S450-650. Our data suggest a possibility that, although the beta6 strand alone is able to bind with ACE2 with relatively high affinity, residues outside the S-RBM could also assist the receptor binding of SARS-CoV-S protein.     

Preparation and comparative evaluation of 99mTc‐HYNIC‐cNGR and 99mTc‐HYNIC‐PEG2‐cNGR as tumor‐targeting molecular imaging probes

The tripeptide sequence asparagine‐glycine‐arginine (NGR) specifically recognizes aminopeptidase N (APN or CD13) receptors highly expressed on tumor cells and vasculature. Thus, NGR peptides can precisely deliver therapeutic and diagnostic compounds to CD13 expressing cancer sites. In this regard, 2 NGR peptide ligands, HYNIC‐c(NGR) and HYNIC‐PEG₂‐c(NGR), were synthesized, radiolabeled with ^99mTc, and evaluated in CD13‐positive human fibrosarcoma HT‐1080 tumor xenografts. The radiotracers, ^99mTc‐HYNIC‐c(NGR) and ^99mTc‐HYNIC‐PEG₂‐c(NGR), could be prepared in approximately 95% radiochemical purity and exhibited excellent in vitro and in vivo stability. The radiotracers were hydrophilic in nature with log P values being ?2.33 ± 0.05 and ?2.61 ± 0.08. The uptake of 2 radiotracers ^99mTc‐HYNIC‐c(NGR) and ^99mTc‐HYNIC‐PEG₂‐c(NGR) was similar in nude mice bearing human fibrosarcoma HT‐1080 tumor xenografts, which was significantly reduced (P < .05) during blocking studies. The 2 radiotracers being hydrophilic cleared rapidly from blood, liver, and intestine and were excreted through renal pathway. The pharmacokinetics of ^99mTc‐labeled HYNIC peptide could not be modulated through introduction of PEG₂ unit, thus posing a challenge for studies with other linkers towards enhanced tumor uptake and retention.     

CXC趋化因子配体14对高糖环境中脂肪细胞焦亡的影响

目的探讨CXC趋化因子配体14(CXCL14)对高糖暴露环境中脂肪细胞焦亡的影响。方法利用“鸡尾酒法”诱导3T3-L1细胞分化为成熟脂肪细胞,用5.5 mmol/L低糖(NG)或25 mmol/L高糖(HG)葡萄糖培养基培养脂肪细胞24 h;HG环境下用不同浓度CXCL14处理3T3-L1细胞不同时间。Western blot检测消化道皮肤素(GSDMD)、核苷酸结合寡聚化结构样受体蛋白3(NLRP3)、天冬氨酸蛋白水解酶-1(Caspase-1)蛋白、白细胞介素-6(IL-6)蛋白表达水平。实时荧光定量PCR检测GSDMD、NLRP3、白细胞介素-1β(IL-1β) mRNA转录水平。LDH测定试剂盒检测脂肪细胞上清液中乳酸脱氢酶(LDH)活力;Annexin V-FITC荧光检测细胞死亡情况;CCK-8法检测各组细胞增殖活力。结果高糖环境下脂肪细胞焦亡发生率升高,CXCL14处理可提高脂肪细胞增殖活力,但脂肪细胞焦亡相关指标却受到CXCL14浓度梯度的不同影响。50 nmol/L CXCL14处理可降低高糖环境下脂肪细胞GSDMD、NLRP3、IL-1β mRNA以及NLRP3蛋白的表达,下调脂肪细胞LDH活力,减少Annexin V-FITC荧光染色细胞死亡率,但25、100、200 nmol/L CXCL14对其焦亡的指标却呈反向趋势。并且50 nmol/L CXCL14干预后脂肪细胞NLRP3、Caspase-1蛋白随干预时间的延长呈先下降再上升趋势。结论CXCL14对高糖环境中脂肪细胞焦亡的影响与其浓度存在相关性。     

Biological and Clinical Consequences of Integrin Binding via a Rogue RGD Motif in the SARS CoV-2 Spike Protein

Although ACE2 (angiotensin converting enzyme 2) is considered the primary receptor for CoV-2 cell entry, recent reports suggest that alternative pathways may contribute. This paper considers the hypothesis that viral binding to cell-surface integrins may contribute to the high infectivity and widespread extra-pulmonary impacts of the SARS-CoV-2 virus. This potential is suggested on the basis of the emergence of an RGD (arginine-glycine-aspartate) sequence in the receptor-binding domain of the spike protein. RGD is a motif commonly used by viruses to bind cell-surface integrins. Numerous signaling pathways are mediated by integrins and virion binding could lead to dysregulation of these pathways, with consequent tissue damage. Integrins on the surfaces of pneumocytes, endothelial cells and platelets may be vulnerable to CoV-2 virion binding. For instance, binding of intact virions to integrins on alveolar cells could enhance viral entry. Binding of virions to integrins on endothelial cells could activate angiogenic cell signaling pathways; dysregulate integrin-mediated signaling pathways controlling developmental processes; and precipitate endothelial activation to initiate blood clotting. Such a procoagulant state, perhaps together with enhancement of platelet aggregation through virions binding to integrins on platelets, could amplify the production of microthrombi that pose the threat of pulmonary thrombosis and embolism, strokes and other thrombotic consequences. The susceptibility of different tissues to virion–integrin interactions may be modulated by a host of factors, including the conformation of relevant integrins and the impact of the tissue microenvironment on spike protein conformation. Patient-specific differences in these factors may contribute to the high variability of clinical presentation. There is danger that the emergence of receptor-binding domain mutations that increase infectivity may also enhance access of the RGD motif for integrin binding, resulting in viral strains with ACE2 independent routes of cell entry and novel integrin-mediated biological and clinical impacts. The highly infectious variant, B.1.1.7 (or VUI 202012/01), includes a receptor-binding domain amino acid replacement, N501Y, that could potentially provide the RGD motif with enhanced access to cell-surface integrins, with consequent clinical impacts.     

Thyrotropin internalization is directed by a highly conserved motif in the seventh transmembrane region of its receptor

The thyrotropin (TSH) receptor is a member of G protein-coupled seven-transmembrane-segment receptors. It is characterized by a large extracellular domain linked to the seven transmembrane segments and ending with a cytoplasmic tail. Sequence alignment shows that a highly conserved motif, NPXXY where X is any amino acid, exists at the boundary between the seventh transmembrane domain and proximal part of the cytoplasmic tail of virtually all G protein-coupled receptors. This motif has been implicated as an internalization signal for several cell surface receptors, such as the low density lipoprotein (LDL), insulin and insulin-like growth factor-1 (IGF-1) receptors. The potential effects of this motif on the TSH receptor signal transduction and receptor-mediated TSH internalization was analysed by replacement of the tyrosine⁶⁷⁸ residue with an alanine residue. This mutation does not impair high affinity TSH binding, but completely abolishes the ability of cAMP response upon TSH stimulation. It also significantly reduces TSH internalization. The role of the cytoplasmic tail of the TSH receptor in receptor-mediated internalization was also assessed. Deletion of up to 56 amino acids from the C-terminus of the cytoplasmic tail enhances TSH internalization as compared to the wild-type receptor. We conclude that tyrosine⁶⁷⁸ in the NPXXY motif is required for efficient receptor-mediated TSH internalization and G protein coupling. The cytoplasmic tail of the TSH receptor may contain sequence domains which could modulate the effects of the NPXXY internalization signal.