On August 27th, the Proceedings of the National Academy of Sciences (PNAS), an international academic journal, published an online paper on the study paper "Architecture of the cell-cell adhesion mediated by sidekicks" of the Institute of Biochemistry and Cell Biology of the Chinese Academy of Sciences, which analyzed the in-situ structure model of the cell adhesion interface mediated by Sidekicks, a cell adhesian molecule, and possible regulatory mechanisms.
cell adhesion is one of the important ways of cell interaction, and it is widely involved in physiological processes such as cell growth and migration, tissue development and organ formation, especially in the formation of neural networks and plasticity regulation.
in past studies, although the crystal structure of many cell adhesion molecules or their fragments has been analyzed, it is not possible to obtain the structural information of the cell interface directly due to technical limitations.
therefore, the way these molecules are organized in the cellular interface and how they regulate it is not clear, which is also the main difficulty in studying cell adhesion and cell interaction.
cell adhesion molecule Sidekick (including Sdk1 and Sdk2) belongs to the IgSF family and plays an important role in the development and formation of the retina and motion perception by forming homologous dipolymer mediated cells.
the molecule has a long extracellular segment, including six Ig-like domains and 13 Fibronectin III (FnIII) domains.
in the study, the team members collaborated with each other, and through electro-mirror observation, it was found that the extracellular segment of the molecule was highly flexible and formed a homologous dipolymer through the N-end Ig-like domain.
the team first analyzed the crystal structure of the N-end dipolymer fragments and obtained the structural information of the formation of the dipolymer.
the next team used fluorescence microscope, high-pressure freezing, photoelectric combination, ultra-thin slicing, electron tomography and biochemical and molecular biology, and other means, studied the assembly mode of The Sdk molecule in the cell interface, and obtained the in situ structure model of the cell adhesion interface.
it turns out that although the outer segment of the molecule is very long, its mediated cell interface is very compact and has a more uniform spacing distribution.
the Ig-like domain is mainly responsible for forming intercellular trans (trans) connections, while the FnIII domain plays a role in stabilizing the cell interface through interaction with cell membranes, thus illustrating the structure and functional roles of different domains in forming cell interfaces and possible regulatory mechanisms.
Due to the large number of IgSF adhesion molecules found, there are many similarities in the composition of its domain.
, the result, the cell adhesion model established by this work is of general significance for understanding the molecularly mediated cell interaction patterns of the IgSF family, in particular, providing a direct structural biological model for the study of cell adhesion in regulating the specificity and plasticity of neural networks.
the research was supported by the Chinese Academy of Sciences and the Fund Committee, as well as the National Center for Protein Science (Shanghai) electro-mirror, composite laser microscope and other technical systems to provide strong assistance.