AIM To explore the components and the distributions of the cytoskeleton network in neoplastic Hep G2 cellsextracted with triton X-100 and (NH4)2SO4.METHODS Using the mouse lung adenocarcinoma cell sublines (C6/C7) with low and high metastasis as acontrol, the human hepatocellular carcinoma cell line (Hep G2) as well as the cell sublines (C6/C7) wasextracted with triton X-100 and/or (NH4)2SO4, then stained with Coomasie blue R250 or labeled withimmunoenzymatic technique to identify the cytokeratin-type or vimentin-type intermediate filamentcomponents and study the distributions of cytoskeleton comparatively.RESULTS Extracted with triton X-100 and/or (NH4)2SO4, then stained with Coomasie blue R250, the cells'cytoskeleton network were showed clearly; still it was very difficult to identify the variations of thecytoskeleton network in morphology by light microscopy when the same cells was extracted with the differentextraction above; compared with the low metastasis cells (C7), most of the high metastasis cells (C6) werelikely showed that the distribution of the cytoskeleton network was more irregular and uneven as well asgathering on one side to the cell neucleus, and so did a few of Hep G2 cells (the percentage of regular andeven distribution of cytoskeleton, C6: 8.0±1.0; C7: 84.0±2.0; Hep G2: 96.0±2.0; n = 500; x2-test,P<0.01). Moreover, extracted with triton X-100 and (NH4)2SO4, then labeled by immunoenzymatictechnique, the mouse lung adenocarcinoma sublines (C6/C7) were positive for cytokeratin antibody only, butthe hepatocellular carcinoma cell (Hep G2) was positive for both cytokeratin and vimentin antibodies.Besides these, in the same cells, the distribution of the intermediate filament network showed by theimmunoenzymatic technique was nearly keeping with that of the cytoskeleton network showed by Coomasieblue R250 stain.CONCLUSION ① It is very difficult to identify the variations of the cytoskeleton network in morphologyby light microscopy when the same cell was extracted with triton X-100 and/or (NH4)2SO4 then stained withCoomasie blue R250 in comparsion. ② The characterizing distribution of the intermediate filament as well asthe ctoskeleton network that was irregular, uneven and gathering on one side to the nucleus in neoplastic cellmight provide a valuable information for studing tumor metastasis. ③ In analysing the components ofintermediate filament protein of malignant tumor cells, the heterogenous proteins (co-expression) must betaken into consideration.

Heavy ion beams with high linear energy transfer exhibit more beneifcial physical and biological performance than conventional X-rays, thus improving the potential of this type of radiotherapy in the treatment of cancer. However, these two radiotherapy modalities both cause inevitable brain injury. The objective of this study was to evaluate the effects of heavy ion and X-ray irra-diation on the cytoskeleton and cytomechanical properties of rat cortical neurons, as well as to determine the potential mechanism of neuronal injury after irradiation. Cortical neurons from 30 new-born mice were irradiated with heavy ion beams at a single dose of 2 Gy and X-rays at a single dose of 4 Gy;subsequent evaluation of their effects were carried out at 24 hours after irradiation. An immunolfuorescence assay showed that after irradiation with both the heavy ion beam and X-rays, the number of primary neurons was signiifcantly decreased, and there was ev-idence of apoptosis. Radiation-induced neuronal injury was more apparent after X-irradiation. Under atomic force microscopy, the neuronal membrane appeared rough and neuronal rigidity had increased. These cell changes were more apparent following exposure to X-rays. Our ifnd-ings indicated that damage caused by heavy ion and X-ray irradiation resulted in the structural distortion and rearrangement of the cytoskeleton, and affected the cytomechanical properties of the cortical neurons. Moreover, this radiation injury to normal neurons was much severer after irradiation with X-rays than after heavy ion beam irradiation.

As a fundamental component of the host cellular cytoskeleton, actin is routinely engaged by infecting viruses. Furthermore, viruses from diverse groups, and infecting diverse hosts, have convergently evolved an array of mechanisms for manipulating the actin cytoskeleton for efifcacious infection. An ongoing chorus of research now indicates that the actin cytoskeleton is critical for viral replication at many stages of the viral life cycle, including binding, entry, nuclear localization, genomic transcription and reverse transcription, assembly, and egress/dissemination. Speciifcally, viruses subvert the force-generating and macromolecular scaffolding properties of the actin cytoskeleton to propel viral surifng, internalization, and migration within the cell. Additionally, viruses utilize the actin cytoskeleton to support and organize assembly sites, and eject budding virions for cell-to-cell transmission. It is the purpose of this review to provide an overview of current research, focusing on the various mechanisms and themes of virus-mediated actin modulation described therein.

The inhibitory effect of SEMA3C/3D mutations on Neuro-2a cells migration and axonal growth in patients with Hirschsprung's disease

Objective:To explore the effect and mechanism of SEMA3C/3D mutations on axonal growth of neurons and cell migration in Hirschsprung's disease (HSCR) patients.Methods:HEK293T cells were transfected with wild-type and mutant SEMA3C/3D plasmids.The supernatants that contained SEMA3C/3D-AP fusion proteins were collected and added into the Neuro-2a cells.The changes in the cell morphology were observed by immunofluorescence staining.The expression and phosphorylation levels of cofilin,ERM and CRMP2 were determined by western blotting.The cell migration rate was measured by transwell assay.Results:Compared with wild type SEMA3D,SEMA3D-P615T mutant suppressed cofilin phosphorylation in Neuro-2a cells (P ＜ 0.05).The neural cells treated by five mutant SEMA3C/3D-AP fusion proteins presented different levels of axon atrophy,growth cone collapse,and sometimes,loss of normal structure.SE MA3C-S329G,SEMA3C-V337M and SEMA3D-P615T mutants cells exhibited a significantly reduced migration rate as compared with wild-type SEMA3C/3D treated cells (P ＜ 0.01).Conclusion:SEMA3C and SEMA3D mutations in HSCR patients could lead to the inhibition of Neuro-2a cells' migration and axonal growth.The mechanism of SEMA3D-P615T mutant might be related to down-regulation of the expression of p-cofilin,which consequently lead to cytoskeleton structure collapse and migrating ability decrease.Our study might provide important clues for the pathogenesis of HSCR.