Inhibition of Abl family kinases produces a profound change in cell shape and migration

Cell migration is fundamental to establishing and maintaining the proper organization of multi-cellular organisms. In this dissertation we reviewed and discussed the biological process of single cell migration in two-dimensional and three-dimensional environments. We reported that Gleevec (Imatinib), an Abl family kinase inhibitor, produces a profound change in the shape and migration of rat bladder tumor cells (NBT-II) plated on collagen-coated substrates. Cells treated with Gleevec adopt a highly spread D-shape (similar to fish keratocytes) and migrate more rapidly with greater persistence. Our finding indicate integrin mediated adhesion changes happened with the inhibition of Abl-family kinases, while RhoA activity increased in this cases, which via myosin activation, led to an increase in the magnitude of total traction force applied to the substrate. We also discovered a special band of small punctate, rapidly turning over adhesions near the leading margin of spread D-shape NBT-IDoctor of Philosoph

Fractional Repetitive Control of Nanopositioning Stages for High-Speed Scanning Using Low-Pass FIR Variable Fractional Delay Filter

This work was supported by the National Natural Science Foundation of China under Grant 51975375, the Binks Trust Visiting Research Fellowship (2018) (University of Aberdeen, UK) awarded to Dr. Sumeet S. Aphale and the SJTU overseas study grant awarded to Linlin Li. The authors would like to thank Mr. Wulin Yan for his assistance with the experiments.Peer reviewedPostprin

Cell Migration

Cell migration is fundamental to establishing and maintaining the proper organization of multicellular organisms. Morphogenesis can be viewed as a consequence, in part, of cell locomotion, from large-scale migrations of epithelial sheets during gastrulation, to the movement of individual cells during development of the nervous system. In an adult organism, cell migration is essential for proper immune response, wound repair, and tissue homeostasis, while aberrant cell migration is found in various pathologies. Indeed, as our knowledge of migration increases, we can look forward to, for example, abating the spread of highly malignant cancer cells, retarding the invasion of white cells in the inflammatory process, or enhancing the healing of wounds. This article is organized in two main sections. The first section is devoted to the single-cell migrating in isolation such as occurs when leukocytes migrate during the immune response or when fibroblasts squeeze through connective tissue. The second section is devoted to cells collectively migrating as part of multicellular clusters or sheets. This second type of migration is prevalent in development, wound healing, and in some forms of cancer metastasis

Scaffold-free, Human Mesenchymal Stem Cell-Based Tissue Engineered Blood Vessels

Tissue-engineered blood vessels (TEBV) can serve as vascular grafts and may also play an important role in the development of organs-on-a-chip. Most TEBV construction involves scaffolding with biomaterials such as collagen gel or electrospun fibrous mesh. Hypothesizing that a scaffold-free TEBV may be advantageous, we constructed a tubular structure (1 mm i.d.) from aligned human mesenchymal cell sheets (hMSC) as the wall and human endothelial progenitor cell (hEPC) coating as the lumen. The burst pressure of the scaffold-free TEBV was above 200 mmHg after three weeks of sequential culture in a rotating wall bioreactor and perfusion at 6.8 dynes/cm2. The interwoven organization of the cell layers and extensive extracellular matrix (ECM) formation of the hMSC-based TEBV resembled that of native blood vessels. The TEBV exhibited flow-mediated vasodilation, vasoconstriction after exposure to 1 μM phenylephrine and released nitric oxide in a manner similar to that of porcine femoral vein. HL-60 cells attached to the TEBV lumen after TNF-α activation to suggest a functional endothelium. This study demonstrates the potential of a hEPC endothelialized hMSC-based TEBV for drug screening

Talin phosphorylation by Cdk5 regulates Smurf1-mediated talin head ubiquitylation and cell migration

Cell migration is a dynamic process that requires temporal and spatial regulation of integrin activation and focal adhesion assembly-disassembly1. Talin, an actin and β integrin tail-binding protein, is essential for integrin activation and focal adhesion formation2,3. Calpain-mediated cleavage of talin plays a key role in focal adhesion turnover3; however, the talin head (TH) domain, one of the two cleavage products, stimulates integrin activation, localizes to focal adhesions, and maintains cell edge protrusions2,4,5, suggesting that additional steps, downstream of talin proteolysis, are required for focal adhesion disassembly. Here we show that TH binds Smurf1, an E3 ubiquitin ligase involved in cell polarity and migration6,7, more tightly than full length talin and that this interaction leads to TH ubiquitination and degradation. TH was a substrate for Cdk5, a regulator of cell migration and cancer metastasis8–11. Cdk5 phosphorylated TH at Ser425, inhibiting its binding to Smurf1, thus preventing TH ubiquitination and degradation. Expression of talS425A, which resists Cdk5 phosphorylation thereby increasing its susceptibility to Smurf1-mediated ubiqitination, resulted in extensive focal adhesion turnover and inhibited cell migration. Thus, TH produced by calpain cleavage of talin, is degraded via Smurf1-mediated ubiquitination; moreover, phosphorylation by Cdk5 regulates Smurf1 binding to TH and, in this way, controls TH turnover and adhesion stability and, ultimately, cell migration

Mechanism of Chromophore Assisted Laser Inactivation Employing Fluorescent Proteins

Chromophore Assisted Laser Inactivation (CALI) is a technique that uses irradiation of chromophores proximate to a target protein to inactivate function. Previously, EGFP mediated CALI has been used to inactivate EGFP-fusion proteins in a spatio-temporally defined manner within cells but the mechanism of inactivation is unknown 1, 2. To help elucidate the mechanism of protein inactivation mediated by fluorescent protein CALI ([FP]-CALI), the activities of purified Glutathione-S-transferase-FP (GST-EXFP) fusions were measured after laser irradiation in vitro. Singlet oxygen and free radical quenchers as well as the removal of oxygen inhibited CALI, indicating the involvement of a reactive oxygen species (ROS). At higher concentrations of protein, turbidity after CALI increased significantly indicating cross-linking of proximate fusion proteins suggesting that damage of residues on the surface the protein, distant from the active site, results in inactivation. Control experiments removed sample heating as a possible cause of these effects. Different FP mutants fused to GST vary in their CALI efficiency in the order EGFP>EYFP>ECFP, while a GST construct that binds FlAsH results in significantly higher CALI efficiency than any of the XFPs tested. It is likely that the hierarchy of XFP effectiveness reflects the balance between ROS that are trapped within the XFP structure and cause fluorophore and chromophore bleaching and those that escape to effect CALI of proximate proteins

ZCCHC13-mediated induction of human liver cancer is associated with the modulation of DNA methylation and the AKT/ERK signaling pathway

Abstract Background Previous studies have shown that zinc-finger CCHC-type containing 13 (ZCCHC13) is located in an imprinted gene cluster in the X-inactivation centre, but few published studies have provided evidence of its expression in cancers. The CCHC-type zinc finger motif has numerous biological activities (such as DNA binding and RNA binding) and mediates protein–protein interactions. In an effort to examine the clinical utility of ZCCHC13 in oncology, we investigated the expression of the ZCCHC13 mRNA and protein in hepatocellular carcinoma (HCC). Methods The expression of the ZCCHC13 mRNA and protein was evaluated using real-time reverse transcriptase-PCR, Western blotting and immunochemistry. DNA methylation was measured by methylation-specific PCR and bisulfite sequencing. The role of ZCCHC13 methylation was further evaluated using the demethylating agent, 5-aza-2′-deoxycytidine. The presence of anti-ZCCHC13 antibodies was determined by an ELISA. Results ZCCHC13 expression was frequently upregulated in human liver cancer cells and tissues. Compared with heathy individuals, sera from patients with HCC displayed a significant response to the recombinant ZCCHC13 protein. The overexpression of ZCCHC13 in HCC was attributed to DNA hypomethylation in the promoter region. Moreover, overexpression of ZCCHC13 in liver cancer cells promoted cell cycle progression by facilitating the G1-S transition, which was related to aberrant activation of the ATK/ERK/c-MYC/CDK pathway. Conclusions Based on our findings, ZCCHC13 functions an oncogene for HCC, and DNA hypomethylation is a driving factor in carcinogenesis

Talin phosphorylation by Cdk5 regulates Smurf1-mediated talin head ubiquitylation and cell migration.

Cell migration is a dynamic process that requires temporal and spatial regulation of integrin activation and focal adhesion assembly/disassembly. Talin, an actin and beta-integrin tail-binding protein, is essential for integrin activation and focal adhesion formation. Calpain-mediated cleavage of talin has a key role in focal adhesion turnover; however, the talin head domain, one of the two cleavage products, stimulates integrin activation, localizes to focal adhesions and maintains cell edge protrusions, suggesting that other steps, downstream of talin proteolysis, are required for focal adhesion disassembly. Here we show that talin head binds Smurf1, an E3 ubiquitin ligase involved in cell polarity and migration, more tightly than full-length talin does and that this interaction leads to talin head ubiquitylation and degradation. We found that talin head is a substrate for Cdk5, a cyclin-dependent protein kinase that is essential for cell migration, synaptic transmission and cancer metastasis. Cdk5 phosphorylated talin head at Ser 425, inhibiting its binding to Smurf1, thus preventing talin head ubiquitylation and degradation. Expression of the mutant tal(S425A), which resists Cdk5 phosphorylation thereby increasing its susceptibility to Smurf1-mediated ubiqitylation, resulted in extensive focal adhesion turnover and inhibited cell migration. Thus, talin head produced by calpain-induced cleavage of talin is degraded through Smurf1-mediated ubiquitylation; moreover, phosphorylation by Cdk5 regulates the binding of Smurf1 to talin head, controlling talin head turnover, adhesion stability and ultimately, cell migration

Evaluation of AMG510 Therapy on KRAS-Mutant Non–Small Cell Lung Cancer and Colorectal Cancer Cell Using a 3D Invasive Tumor Spheroid System under Normoxia and Hypoxia

A 3D tumor spheroid has been increasingly applied in pharmaceutical development for its simulation of the tumor structure and microenvironment. The embedded-culture of a tumor spheroid within a hydrogel microenvironment could help to improve the mimicking of in vivo cell growth and the development of 3D models for tumor invasiveness evaluation, which could enhance its drug efficiency prediction together with cell viability detection. NCI-H23 spheroids and CT-26 spheroids, from a non–small cell lung cancer and colorectal cancer cell line, respectively, together with extracellular matrix were generated for evaluating their sensitivity to AMG510 (a KRASG12C inhibitor) under normoxia and hypoxia conditions, which were created by an on-stage environmental chamber. Results demonstrated that NCI-H23, the KRASG12C moderate expression cell line, only mildly responded to AMG510 treatment in normal 2D and 3D cultures and could be clearly evaluated by our system in hypoxia conditions, while the negative control CT-26 (G12D-mutant) spheroid exhibited no significant response to AMG510 treatment. In summary, our system, together with a controlled microenvironment and imaging methodology, provided an easily assessable and effective methodology for 3D in vitro drug efficiency testing and screenings