Abstract
Cell migration is an essential cellular process that requires coordination of cytoskeletal dynamics, reorganization, and signal transduction. The actin cytoskeleton is central in maintaining the cellular structure as well as regulating the mechanisms of cell motility. Glycosylation, particularly sialylation of cell surface proteins like integrins, regulates signal transduction from the extracellular matrix to the cytoskeletal network. The activation of integrin by extracellular cues leads to recruitment of different focal adhesion complex proteins (Src, FAK, paxillin, etc.) and activates the signal including Rho GTPases for the regulation of actin assembly and disassembly. During cell migration, the assembly and disassembly of actin filament provides the essential force for the cell to move. Abnormal sialylation can lead to actin signaling dysfunction leading to aberrant cell migration, one of the main characteristics of cancer and myopathies. In the present study, we have reported altered F-actin to G-actin ratios in GNE mutated cells. These cells exhibit pathologically relevant mutations of GNE (UDP N-acetylneuraminic 2-epimerase/N-acetylmannosamine kinase), a key sialic acid biosynthetic enzyme. It was found that GNE neither affects the actin polymerization nor binds directly to actin. However, mutation in GNE resulted in increased binding of α-actinin to actin filaments. Further, through confocal imaging, GNE was found to be localized in focal adhesion complex along with paxillin. We further elucidated that mutation in GNE resulted in upregulation of RhoA protein and Cofilin activity is downregulated, which could be rescued with Rhosin and chlorogenic acid, respectively. Lastly, mutant in GNE reduced cell migration as implicated from wound healing assay. Our study indicates that molecules altering Cofilin function could significantly revert the cell migration defect due to GNE mutation in sialic acid-deficient cells. We propose cytoskeletal proteins to be alternate drug targets for disorders associated with GNE such as GNE myopathy.
Highlights
Cell adhesion and migration is a key function of cells, mediated by complex fibrous network of protein filaments in the cytoplasm creating what is known as cytoskeleton
How changes in sialic acid content affect actin dynamic levels in UDP N-acetylneuraminic 2-epimerase/Nacetylmannosamine kinase (GNE)-deficient cells was studied by determining F/globular actin (G-actin) ratio in these cells
Our study indicates that in the presence of mutant GNE proteins, F/G-actin dynamic levels are reduced in the cells that may affect overall the cytoskeletal network in the cell
Summary
Cell adhesion and migration is a key function of cells, mediated by complex fibrous network of protein filaments in the cytoplasm creating what is known as cytoskeleton. The function of actin relies primarily on the dynamic assembly and disassembly of actin filaments into monomeric G (globular) actin and filamentous F (filamentous) actin forms. Actin Dynamics in GNE Mutant Cells of actins assemble to form F-actin filaments of 7 nm along with various actin-binding proteins (Ananthakrishnan and Ehrlicher, 2007; Lee and Dominguez, 2010). The formation of actin trimer triggers elongation of actin monomers into a righthanded helical polymer with two distinct ends—barbed end and pointed end. Active polymerization occurs at the barbed end while depolymerization occurs at the pointed end. The turnover rate of filaments is tightly regulated by depolymerizing factors such as Cofilin and capping proteins (Sousa-Squiavinato et al, 2019). A large number of Factin binding and bundling proteins determine fate, longevity, and function of actin filaments (Biron and Moses, 2004)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
