Introduction to vimentin
Vimentin is one of the proteins of the middle filament. The middle silk is an important structural feature of eukaryotic cells. They are microcapsules with microtubules and actin to form a cytoskeleton.
Vimentin was also found to be responsible for controlling the transmission of cholesterol from lysosomes from low density lipoprotein (LDL) to the esterification site. Vimentin is one of the proteins of the middle filament. A vimentin monomer, similar to other intermediate filaments, has a central alpha helix domain with a non-helical amino group at its front end and a carboxyl group at the end. The two monomers will twist each other to form a curled coil-shaped dimer. The dynamic nature of vimentin is very important for cell flexibility. In the test tube pressure test found that vimentin can provide microtubules and actin does not have the flexibility, so the vimentin is responsible for maintaining the integrity of the cytoskeleton.
The structure of the vimentin
A vimentin monomer, similar to other intermediate filaments, has a central alpha helix domain with a non-helical amino group at its front end and a carboxyl group at the end. The two monomers will twist each other to form a curled coil-shaped dimer. The two dimers will further form a tetramer, and then connected with other tetramers into one.
The alpha helix sequence contains a set of hydrophobic amino acids that form a “hydrophobic barrier” on the helical surface. This barrier allows two spirals to curl each other. Furthermore, there is a cyclical distribution of acidic and basic amino acids, can balance the coiled helical dimer. The spacing between the charged harsh residues is the best place to establish an ion salt bridge, and the same can stabilize the alpha helix structure. Scientists believe that this salt bridge can not only provide the inner chain of the interaction, when it is changed from the salt bridge to the outer chain of ions, can cause intermediate silk.
Scientists have found that vimentin is attached to the nucleus, endoplasmic reticulum and mitochondria next to the end or end, and thus believe that vimentin in the support and anchoring of the original organism within the organ has an important role. It also maintains the shape of the cell, the integrity of the cytoplasm and the stability of the cytoskeleton of the interaction.
The role of vimentin
The dynamic nature of vimentin is very important for cell flexibility. In the test tube pressure test found that vimentin can provide microtubules and actin does not have the flexibility, so the vimentin is responsible for maintaining the integrity of the cytoskeleton. In addition, cells that do not have vimentin are subjected to less acupuncture and can cause serious injury. In the experimental mice that excluded the vimentin gene, although they had normal function, the microtubule was damaged by loss of vimentin. This reinforces the intimate interaction between microtubules and vimentin. Furthermore, when the microtubule depolymer appears, the vimentin reorganizes and reaffirms the relationship between the two systems.
Vimentin was also found to be responsible for controlling the transmission of cholesterol from lysosomes from low density lipoprotein (LDL) to the esterification site. When this transport is blocked, the cells will accumulate less lipoproteins than usual. This relationship is the first biochemical process that requires cells that rely on intermediate wire mesh and also branches in adrenal cells, depending on the production of cholesterol esters from LDL.
Vimentin and cell dedifferentiation
In cytokeratin-positive epithelial tumors, simultaneous vimentin expression is a manifestation of the tumor’s “rejuvenation” to embryonic period. The expression of vimentin in MGC8023 cell line was induced by hexamethylenebisacetamide (HMBA), which indicated that vimentin may be involved in the growth and differentiation of gastric cancer cells. The expression of intermediate fibrin has tissue and cell specificity, especially the diversity of end sequences and so on suggest that intermediate fibers are involved in cell differentiation, signal transduction, gene regulation and so on.
In the process of embryonic development of vertebrates, the expression of intermediate fibrin has a certain stage, which indicates that intermediate fibers play an important role in the differentiation of cells. The germinal layer is the site of epithelial cell division. The cells side of the differentiation, while the skin to the epithelial movement, until the peel from the epithelium. The germinal layer cells have many intermediate fiber bundles composed of anterior keratin. With the process of cell terminal differentiation, the anterior keratin transcribes different keratin mRNAs and is translated into the corresponding protein.
Vimentin and keratin belong to the middle fiber and the relationship is closely related to whether the two in the cell differentiation from the need for further study. Some of the more primitive stem cell marker molecules, such as vimentin, are likely to be re-expressed in tumor tissue due to their large heterogeneity and poorly differentiated features. Embryonic development and pancreatic neoplasia, the proliferation of pancreatic duct epithelium can be highly expressed, there may be a proliferation of pancreatic progenitor cells in the marker. On the vimentin-positive tumor cell source, Yin Tao, etc. to make several explanations: ① tumor tissue in the muscle epithelial cells; ② the differentiated tumor cells; ③ have a variety of differentiated potential of tumor progenitor cells.
Summary of vimentin
To study the expression of vimentin in different tissues and different periods, it is helpful to understand the state, process and influencing factors of cell differentiation, early detection of malignant tumors and take appropriate prevention and treatment measures. The discussion of the physiological functions of vimentin can help to understand the occurrence and development of malignant tumors and it is possible to find new therapeutic target genes. The expression of vimentin in tumor tissues, metastases, lymph nodes, peripheral blood and exfoliated cells is helpful to the diagnosis and classification of tumor, metastasis, follow-up, prognosis and guidance.