Thrombospondin (TSP) 1 is a trimeric extracellular matrix protein that is held together by two cysteine residues. It is one of five TSP proteins that have been described to date with almost universal heparin binding capacity (TSP5 is an exception).
Introductions about Thrombospondin Family Proteins
The thrombospondin (TSP) gene family consists of five genes with high homology to the primary structure. They are divided into two groups of structures and sizes according to quaternions. Members of the first group, including TSP1 and TSP2 are both 450 kDa homotrimers, while members of the second group include TSP3, TSP4, and TSP5 and are pentene. The presence of conserved amino acids between these homology can prove that the protein is called type I, type II and type III repeats. Both TSP1 and TSP2 have three type I repeats, three type II repeats, and seven type III repeats. TSP3, TSP4, and TSP5, the other hand, are missing all type I duplicates, but have an additional type II duplicate. The TSP1 monomer contains two key residues at positions 254 and 256 that are thought to mediate formation and assembly of trimers. Similarly, residues at positions 245 and 248 of the two cysteine TSP3 monomers stabilize the five-chain pentamer. TSP3 has a unique primary and quaternary structure, which indicates that it is different from TSP1. It was found to express mouse embryos in development, but has not yet attributed the function to TSP3 in adults. TSP1 is an extracellular matrix (ECM) glycoprotein that is involved in angiogenesis. New blood vessels sprout from existing blood vessels. It has been shown to have a strong antiangiogenic effect and to participate in tumor therapeutic inhibitory activity as an effector molecule of the tumor suppressor gene p53. Anti-angiogenic activity is localized to three 60-residue fragments of type I that are repeated with malaria proteins, properdin, and complement homologs C6-C9. Several synthetic peptides derived therefrom have proven that this domain is a potent anti-angiogenic agent. Consistent with these findings, another protein containing type I repeats, TSP2, also has antiangiogenic activity. In a recent study, a strong correlation was to establish angiogenesis and progression of transitional cell carcinoma between TSP1 expression levels and tumors. bladder. However, some studies report the pro-angiogenic effect of TSP1 in wound and tumor cell healing. In addition, early research on platelet TSP (TSP1) consistently showed that TSP promotes cell proliferation, migration, and adhesion, all of which are essential components of angiogenesis. We believe that in terms of TSP, the difference between the two groups may be due to at least two other factors (apart from the differential acid sequence of the primary amino group): the level of local expression and the three-dimensional structure of the oligomer (trimer vs. pentamer).
The thrombospondin-1 protein is a member of the thrombospondin family. It is a multidomain matrix glycoprotein that has been shown to be a natural inhibitor of neovascularization and tumorigenesis in healthy tissues. Both positive and negative modulation of endothelial cell adhesion, motility and growth are attributed to TSP1. Considering that TSP1 interacts with at least 12 cell adhesion receptors, including CD36, αv integrin, β1 integrin, syndecan and integrin-related proteins (IAP or CD47), this is not surprising. It also interacts with many proteases involved in angiogenesis, including plasminogen, urokinase, matrix metalloproteinases, thrombin, cathepsin, and elastase. Thrombospondin-1 binds to the reelin receptors Apo ER2 and VLDLR, thereby affecting neuron migration in nasal migration flow. The various functions of TSR have been attributed to several identification topics. The characterization of these motifs has led to the use of recombinant proteins containing these motifs. These recombinant proteins are considered useful for cancer treatment. TSP-1 3TSR (recombinant version of THBS1 anti-angiogenic domain, containing all three TRP-1 type 1 repeats) can activate transforming growth factor β1 (TGFβ1) and inhibit endothelial cell migration, angiogenesis and tumor growth.