Single-Cell Transcriptional Profiling Reveals Cellular Diversity and Intercommunication in the Mouse Heart

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基于包膜蛋白和Tat蛋白筛选HIV-1细胞融合抑制剂的高效方法

旨在建立一个细胞-细胞融合系统,高效筛选对HIV-1病毒细胞-细胞间传播有抑制作用的药物。构建了p EGFP-Tat质粒,将p EGFP-Tat质粒和HIV-1包膜质粒共转染HEK-293T细胞,成为表达Tat蛋白和包膜蛋白的效应细胞,然后与表达CD4及辅助受体和β-半乳糖苷酶、荧光素酶双报告基因的靶细胞TZM-bl融合,建立了细胞-细胞融合系统,并进行条件优化,确定了最佳的融合体系。用阳性融合抑制剂maraviroc以及没有融合抑制作用的AZT和raltegravir作用于该体系,证明该系统可以特异性有效筛选具有细胞融合抑制作用的药物。用该系统测试了8个样本,发现两种样品对融合有一定的抑制作用。该方法背景值低,特异性强,可用来高效筛选具有切断HIV-1病毒细胞-细胞间传播作用的抗病毒药物。     

Circuit Design Features of a Stable Two-Cell System

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The Mechanism and Consequences of SARS-CoV-2 Spike-Mediated Fusion and Syncytia Formation

Syncytia are formed when individual cells fuse. SARS-CoV-2 induces syncytia when the viral spike (S) protein on the surface of an infected cell interacts with receptors on neighboring cells. Syncytia may potentially contribute to pathology by facilitating viral dissemination, cytopathicity, immune evasion, and inflammatory response. SARS-CoV-2 variants of concern possess several mutations within the S protein that enhance receptor interaction, fusogenicity and antibody binding. In this review, we discuss the molecular determinants of S mediated fusion and the antiviral innate immunity components that counteract syncytia formation. Several interferon-stimulated genes, including IFITMs and LY6E act as barriers to S protein-mediated fusion by altering the composition or biophysical properties of the target membrane. We also summarize the effect that the mutations associated with the variants of concern have on S protein fusogenicity. Altogether, this review contextualizes the current understanding of Spike fusogenicity and the role of syncytia during SARS-CoV-2 infection and pathology.     

Microtubules tethered at epithelial cell junctions by dynein facilitate efficient junction assembly

Efficient remodeling of cell-cell adhesions is critical during development and morphogenesis. Junctional components must be specifically and rapidly transported to sites of junction assembly. In this study, we show a mechanism by which this targeted trafficking may occur. Microtubules target epithelial adherens junctions, and the number of microtubules both projecting to and tethered at sites of contact is increased during junction assembly, consistent with an increased need for new material at the nascent junction. Cytoplasmic dynein is localized to sites of cell-cell contact, and microtubules project to dynein patches where they become tethered. Microinjection of anti-dynein antibodies disrupts the tethering of microtubules, showing that the motor anchors them. Furthermore, disruption of dynein inhibits junction formation. Immunocytochemistry with antibodies to p120 catenin support the hypothesis that tethered microtubules serve as tracks for delivery of new components to forming junctions, suggesting a model in which material is targeted for delivery to sites of need through microtubules tethered by dynein.     

Vascular Endothelial Receptor Tyrosine Phosphatase: Identification of Novel Substrates Related to Junctions and a Ternary Complex with EPHB4 and TIE2,

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Highlights

• •Identification of the substrates profile of the endothelial phosphatase VE-PTP.
• •A large fraction of VE-PTP substrate candidates (29%) is cell junction related.
• •Tie-2 and EPHB are substrates which associate as ternary complex with VE-PTP.

     

Cell Migration and Cell-Cell Interaction in the Presence of Mechano-Chemo-Thermotaxis

Although there are several computational models that explain the trajectory that cells take during migration, till now little attention has been paid to the integration of the cell migration in a multi-signaling system. With that aim, a generalized model of cell migration and cell-cell interaction under multisignal environments is presented herein. In this work we investigate the spatio-temporal cell-cell interaction problem induced by mechano-chemo-thermotactic cues. It is assumed that formation of a new focal adhesion generates traction forces proportional to the stresses transmitted by the cell to the extracellular matrix. The cell velocity and polarization direction are calculated based on the equilibrium of the effective forces associated to cell motility. It is also assumed that, in addition to mechanotaxis signals, chemotactic and thermotactic cues control the direction of the resultant traction force. This model enables predicting the trajectory of migrating cells as well as the spatial and temporal distributions of the net traction force and cell velocity. Results indicate that the tendency of the cells is firstly to reach each other and then migrate towards an imaginary equilibrium plane located near the source of the signal. The position of this plane is sensitive to the gradient slope and the corresponding efficient factors. The cells come into contact and separate several times during migration. Adding other cues to the substrate (such as chemotaxis and/or thermotaxis) delays that primary contact. Moreover, in all states, the average local velocity and the net traction force of the cells decrease while the cells approach the cues source. Our findings are qualitatively consistent with experimental observations reported in the related literature.     

Neuronal development in the Drosophila compound eye: Photoreceptor cells R1, R6, and R7 fail to differentiate in the retina aberrant in pattern (rap) mutant

The compound eye of Drosophila is a reiterated pattern of 800 unit eyes known as ommatidia. In each ommatidium there are eight photoreceptor neurons (R1–R8) and an invariant number of accessory cells organized in a precise manner. In the developing eye, specification of cell fates is triggered by sequential inductive events mediated by cell-cell interactions. The R8 photoreceptor neuron is the first cell to differentiate and is thought to play a central role in the recruitment of the remaining photoreceptor cells. Our previous work demonstrated that mutations in the retina aberrant in pattern (rap) locus lead to abnormal pattern formation in the compound eye. Genetic mosaic experiments demonstrated that for normal retinal patterning to occur, rap gene function is required only in the photoreceptor cell R8. In this study we analyzed the R cell composition of developing as well as the adult eyes of rap mutants employing a variety of R cell specific markers. We show that in rap mutants, although some of the R8-specific markers show normal expression patterns, other aspects of the R8 cell differentiation are abnormal. In addition, the cells R1, R6, and R7 fail to differentiate properly in rap mutants. These results suggest that the rap gene encodes an R8-specific function that plays a role in the determination of the photoreceptor cells R1, R6, and R7. © 1996 John Wiley & Sons, Inc.