Nicotiana benthamiana Class 1 Reversibly Glycosylated Polypeptides Suppress Tobacco Mosaic Virus Infection.

Reversibly glycosylated polypeptides (RGPs) have been identified in many plant species and play an important role in cell wall formation, intercellular transport regulation, and plant-virus interactions. Most plants have several RGP genes with different expression patterns depending on the organ and developmental stage. Here, we report on four members of the RGP family in N. benthamiana. Based on a homology search, NbRGP1-3 and NbRGP5 were assigned to the class 1 and class 2 RGPs, respectively. We demonstrated that NbRGP1-3 and 5 mRNA accumulation increases significantly in response to tobacco mosaic virus (TMV) infection. Moreover, all identified class 1 NbRGPs (as distinct from NbRGP5) suppress TMV intercellular transport and replication in N. benthamiana. Elevated expression of NbRGP1-2 led to the stimulation of callose deposition at plasmodesmata, indicating that RGP-mediated TMV local spread could be affected via a callose-dependent mechanism. It was also demonstrated that NbRGP1 interacts with TMV movement protein (MP) in vitro and in vivo. Therefore, class 1 NbRGP1-2 play an antiviral role by impeding intercellular transport of the virus by affecting plasmodesmata callose and directly interacting with TMV MP, resulting in the reduced viral spread and replication.

Lamin A as a Determinant of Mechanical Properties of the Cell Nucleus in Health and Disease.

One of the main factors associated with worse prognosis in oncology is metastasis, which is based on the ability of tumor cells to migrate from the primary source and to form secondary tumors. The search for new strategies to control migration of metastatic cells is one of the urgent issues in biomedicine. One of the strategies to stop spread of cancer cells could be regulation of the nuclear elasticity. Nucleus, as the biggest and stiffest cellular compartment, determines mechanical properties of the cell as a whole, and, hence, could prevent cell migration through the three-dimensional extracellular matrix. Nuclear rigidity is maintained by the nuclear lamina, two-dimensional network of intermediate filaments in the inner nuclear membrane (INM). Here we present the most significant factors defining nucleus rigidity, discuss the role of nuclear envelope composition in the cell migration, as well consider possible approaches to control lamina composition in order to change plasticity of the cell nucleus and ability of the tumor cells to metastasize.

The role of vimentin in directional migration of rat fibroblasts.

Cell migration is one of the most important processes in which the cytoskeleton plays a main role. The cytoskeleton network is formed by tubulin microtubules, actin filaments, and intermediate filaments (IFs). While the structure and functions of the two aforementioned proteins have been extensively investigated during the last decades, vimentin IFs structure and their role in cell migration and adhesion remain unclear. Here, we investigated polarity determination in rat fibroblasts with either a knocked out vim gene or with a mutation that blocks filament formation on the stage of unit-length filaments (ULFs). Structured illumination microscopy has demonstrated the difference in the morphology of IFs in wild-type fibroblasts and of ULFs in mutant fibroblasts. We have developed an approach to measure cell stiffness separately on the trailing and leading edges using atomic force microscopy. Young's modulus values on the leading and trailing edge of migrating rat fibroblasts differ approximately by two times, being larger on the leading edge. The knockout of the vim gene leads to having comparable values of Young's moduli on both edges. Vimentin-null cells change the direction of migration more frequently than those expressing wild-type or mutated vimentin. Our results have shown the principle role of vimentin, not only in the form of IFs, but also as ULFs, in the determination of the polarity and the directionality of fibroblast migration.