High-speed broadband monitoring of cell viscoelasticity in real time shows myosin-dependent oscillations

Study of the dynamic evolutions of cell viscoelasticity is important as during cell activities such as cell metastasis and invasion, the rheological behaviors of the cells also change dynamically, reflecting the biophysical and biochemical connections between the outer cortex and the intracellular structures. Although the time variations of the static modulus of cells have been investigated, few studies have been reported on the dynamic variations of the frequency-dependent viscoelasticity of cells. Measuring and monitoring such dynamic evolutions of cells at nanoscale can be challenging as the measurement needs to meet two objectives inherently contradictory to each other—the measurement must be broadband (to cover a large frequency spectrum) but also rapid (to capture the time-elapsed changes). In this study, we exploited a recently developed control-based nanomechanical protocol of atomic force microscope to monitor in real time the dynamic evolutions of the viscoelasticity of live human prostate cancer cells (PC-3 cells) and study its dependence on myosin activities. We found that the viscoelasticity of PC-3 cells, followed the power law, and oscillated at a period of about 200 s. Both the amplitude and the frequency of the oscillation strongly depended on the intracellular calcium and blebbistatin-sensitive motor proteins.     

Encapsulating Trogtalite CoSe2 Nanobuds into BCN Nanotubes as High Storage Capacity Sodium Ion Battery Anodes

Trogtalite CoSe₂ nanobuds encapsulated into boron and nitrogen codoped graphene (BCN) nanotubes (CoSe₂@BCN‐750) are synthesized via a concurrent thermal decomposition and selenization processes. The CoSe₂@BCN‐750 nanotubes deliver an excellent storage capacity of 580 mA h g^?1 at current density of 100 mA g^?1 at 100th cycle, as the anode of a sodium ion battery. The CoSe₂@BCN‐750 nanotubes exhibit a significant rate capability (100–2000 mA g^?1 current density) and high stability (almost 98% storage retention after 4000 cycles at large current density of 8000 mA g^?1). The reasons for these excellent storage properties are illuminated by theoretical calculations of the relevant models, and various possible Na⁺ ion storage sites are identified through first‐principles calculations. These results demonstrate that the insertion of heteroatoms, B–C, N–C as well as CoSe₂, into BCN tubes, enables the observed excellent adsorption energy of Na⁺ ions in high energy storage devices, which supports the experimental results.     

Ubiquitin-coated nanodiamonds bind to autophagy receptors for entry into the selective autophagy pathway

Selective macroautophagy/autophagy plays a pivotal role in the processing of foreign pathogens and cellular components to maintain homeostasis in human cells. To date, numerous studies have demonstrated the uptake of nanoparticles by cells, but their intracellular processing through selective autophagy remains unclear. Here we show that carbon-based nanodiamonds (NDs) coated with ubiquitin (Ub) bind to autophagy receptors (SQSTM1 [sequestosome 1], OPTN [optineurin], and CALCOCO2/NDP52 [calcium binding and coiled-coil domain 2]) and are then linked to MAP1LC3/LC3 (microtubule-associated protein 1 light chain 3) for entry into the selective autophagy pathway. NDs are ultimately delivered to lysosomes. Ectopically expressed SQSTM1-green fluorescence protein (GFP) could bind to the Ub-coated NDs. By contrast, the Ub-associated domain mutant of SQSTM1 (ΔUBA)-GFP did not bind to the Ub-coated NDs. Chloroquine, an autophagy inhibitor, prevented the ND-containing autophagosomes from fusing with lysosomes. Furthermore, autophagy receptors OPTN and CALCOCO2/NDP52, involved in the processing of bacteria, were found to be involved in the selective autophagy of NDs. However, ND particles located in the lysosomes of cells did not induce mitotic blockage, senescence, or cell death. Single ND clusters in the lysosomes of cells were observed in the xenografted human lung tumors of nude mice. This study demonstrated for the first time that Ub-coated nanoparticles bind to autophagy receptors for entry into the selective autophagy pathway, facilitating their delivery to lysosomes.     

Characterization of the interactions of a bifunctional inhibitor with alpha-thrombin by molecular modelling and peptide synthesis.

A potent thrombin inhibitor, [D-Phe45, Arg47] hirudin 45-65, that contains an active site-directed sequence D-Phe-Pro-Arg-Pro, an exosite specific fragment hirudin 55-65 (H55-65) and a linker portion hirudin 49-54, was designed based on the hirudin sequence [DiMaio et al. (1990) J. Biol. Chem., 265, 21698-21798]. A three-dimensional model of the complex between the B-chain of human thrombin and the inhibitor [D-Phe45, Arg47] hirudin 45-65 was constructed using molecular modelling starting from the X-ray C alpha coordinates of the thrombin-hirudin complex and the NMR-derived structure of the thrombin-bound hirudin 55-65. The contribution of the H49-54 fragment to the thrombin-inhibitor interaction was deduced by examining a series of analogs containing single glycine substitution and analogs with reduced number of residues within the linker. The results were consistent with the molecular modelling observations i.e. the H49-54 fragment serves the role of a spacer in the binding interaction and could be replaced by four glycine residues. The studies on the interaction of the exosite-directed portion of the inhibitor with thrombin using a series of synthetic H55-65 analogs demonstrated that residues AspH55 to ProH60 play a major role in binding to human thrombin where the side chains of PheH56, IleH59 and GluH57 showed critical contributions. Molecular modelling suggested that these side chains may contribute to inter- and intramolecular hydrophobic and electrostatic interactions, respectively.     

FBXO44 promotes DNA replication-coupled repetitive element silencing in cancer cells

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Circ_0002984 induces proliferation,migration and inflammation response of VSMCs induced by ox-LDL through miR‑326-3p/VAMP3 axis in atherosclerosis

Atherosclerosis can result in multiple cardiovascular diseases. Circular RNAs (CircRNAs) have been reported as significant non-coding RNAs in atherosclerosis progression. Dysfunction of vascular smooth muscle cells (VSMCs) is involved in atherosclerosis. However, up to now, the effect of circ_0002984 in atherosclerosis is still unknown. Currently, we aimed to investigate the function of circ_0002984 in VSMCs incubated by oxidized low-density lipoprotein (ox-LDL). Firstly, our findings indicated that the expression levels of circ_0002984 were significantly up-regulated in the serum of atherosclerosis patients and ox-LDL-incubated VSMCs. Loss of circ_0002984 suppressed VSMC viability, cell cycle distribution and migration capacity. Then, we carried out ELISA assay to determine TNF-α and IL-6 levels. The data implied that lack of circ_0002984 obviously repressed ox-LDL–stimulated VSMC inflammation. Meanwhile, miR-326-3p, which was predicted as a target of circ_0002984, was obviously down-regulated in VSMCs treated by ox-LDL. Additionally, after overexpression circ_0002984 in VSMCs, a decrease in miR-326-3p was observed. Subsequently, miR-326-3p was demonstrated to target vesicle-associated membrane protein 3 (VAMP3). Therefore, we hypothesized that circ_0002984 could modulate expression of VAMP3 through sponging miR-326-3p. Furthermore, we confirmed that up-regulation of miR-326-3p rescued the circ_0002984 overexpressing-mediated effects on VMSC viability, migration and inflammation. Additionally, miR-326-3p inhibitor-mediated functions on VSMCs were reversed by knockdown of VAMP3. In conclusion, circ_0002984 mediated cell proliferation, migration and inflammation through modulating miR-326-3p and VAMP3 in VSMCs, which suggested that circ_0002984 might hold great promise as a therapeutic strategy for atherosclerosis.     

Spatial analysis of hepatocellular carcinoma and socioeconomic status in China from a Population-based Cancer Registry

Background: Little is known about geographic variations in liver cancer at high incident regions. We aimed to identify spatial variation of hepatocellular carcinoma (HCC) at a high-risk area in China and determine its association with socioeconomic status (SES). Methods: Based on 2299 liver cancer cases diagnosed in Haimen from 2003 to 2006, we calculated age–sex standardized incidence ratios (SIRs) and used two spatial scan statistics to determine the geographic variations in HCC. Bayesian hierarchical model was used to explore the association between HCC incidence and SES. Results: Age and sex SIRs for HCC varied from 0.54 to 1.97 for 24 townships. The eastern region of Haimen was identified to have a significantly increased risk of HCC. Fitting of a Bayesian hierarchical model linking per-capita fiscal revenue with SIRs of HCC indicated that the area with a lower revenue had a significantly higher incidence of HCC [β_log(revenue) = ?0.179, posterior 95% Bayesian credible interval (CI) = (?0.326, ?0.04)]. Conclusions: This study demonstrated substantial geographic variation in the incidence of HCC within a high-risk region, which was associated with SES. HCC control and intervention should focus on disadvantaged areas to reduce the HCC disparities.     

Molecular endpoints of Ca2+/calmodulin- and voltage-dependent inactivation of Cav1.3 channels

Ca²⁺/calmodulin- and voltage-dependent inactivation (CDI and VDI) comprise vital prototypes of Ca²⁺ channel modulation, rich with biological consequences. Although the events initiating CDI and VDI are known, their downstream mechanisms have eluded consensus. Competing proposals include hinged-lid occlusion of channels, selectivity filter collapse, and allosteric inhibition of the activation gate. Here, novel theory predicts that perturbations of channel activation should alter inactivation in distinctive ways, depending on which hypothesis holds true. Thus, we systematically mutate the activation gate, formed by all S6 segments within Ca_V1.3. These channels feature robust baseline CDI, and the resulting mutant library exhibits significant diversity of activation, CDI, and VDI. For CDI, a clear and previously unreported pattern emerges: activation-enhancing mutations proportionately weaken inactivation. This outcome substantiates an allosteric CDI mechanism. For VDI, the data implicate a “hinged lid–shield” mechanism, similar to a hinged-lid process, with a previously unrecognized feature. Namely, we detect a “shield” in Ca_V1.3 channels that is specialized to repel lid closure. These findings reveal long-sought downstream mechanisms of inactivation and may furnish a framework for the understanding of Ca²⁺ channelopathies involving S6 mutations.