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21.
Thomas P. Kohler Nicolas Gisch Ulrike Binsker Martin Schlag Katrin Darm Uwe V?lker Ulrich Z?hringer Sven Hammerschmidt 《The Journal of biological chemistry》2014,289(7):4070-4082
Human thrombospondin 1 (hTSP-1) is a matricellular glycoprotein facilitating bacterial adherence to and invasion into eukaryotic cells. However, the bacterial adhesin(s) remain elusive. In this study, we show a dose-dependent binding of soluble hTSP-1 to Gram-positive but not Gram-negative bacteria. Diminished binding of soluble hTSP-1 to proteolytically pretreated staphylococci suggested a proteinaceous nature of potential bacterial adhesin(s) for hTSP-1. A combination of separation of staphylococcal surface proteins by two-dimensional gel electrophoresis with a ligand overlay assay with hTSP-1 and identification of the target protein by mass spectrometry revealed the major staphylococcal autolysin Atl as a bacterial binding protein for hTSP-1. Binding experiments with heterologously expressed repeats of the AtlE amidase from Staphylococcus epidermidis suggest that the repeating sequences (R1ab-R2ab) of the N-acetyl-muramoyl-l-alanine amidase of Atl are essential for binding of hTSP-1. Atl has also been identified previously as a staphylococcal vitronectin (Vn)-binding protein. Similar to the interaction with hTSP-1, the R1ab-R2ab repeats of Atl are shown here to be crucial for the interaction of Atl with the complement inhibition and matrix protein Vn. Competition assays with hTSP-1 and Vn revealed the R1ab-R2ab repeats of AtlE as the common binding domain for both host proteins. Furthermore, Vn competes with hTSP-1 for binding to Atl repeats and vice versa. In conclusion, this study identifies the Atl repeats as bacterial adhesive structures interacting with the human glycoproteins hTSP-1 and Vn. Finally, this study provides insight into the molecular interplay between hTSP-1 and Vn, respectively, and a bacterial autolysin. 相似文献
22.
Nicole E. Calabro Nina J. Kristofik Themis R. Kyriakides 《Biochimica et Biophysica Acta (BBA)/General Subjects》2014
Background
Numerous proteins and small leucine-rich proteoglycans (SLRPs) make up the composition of the extracellular matrix (ECM). Assembly of individual fibrillar components in the ECM, such as collagen, elastin, and fibronectin, is understood at the molecular level. In contrast, the incorporation of non-fibrillar components and their functions in the ECM are not fully understood.Scope of review
This review will focus on the role of the matricellular protein thrombospondin (TSP) 2 in ECM assembly. Based on findings in TSP2-null mice and in vitro studies, we describe the participation of TSP2 in ECM assembly, cell–ECM interactions, and modulation of the levels of matrix metalloproteinases (MMPs).Major conclusions
Evidence summarized in this review suggests that TSP2 can influence collagen fibrillogenesis without being an integral component of fibrils. Altered ECM assembly and excessive breakdown of ECM can have both positive and negative consequences including increased angiogenesis during tissue repair and compromised cardiac tissue integrity, respectively.General significance
Proper ECM assembly is critical for maintaining cell functions and providing structural support. Lack of TSP2 is associated with increased angiogenesis, in part, due to altered endothelial cell–ECM interactions. Therefore, minor changes in ECM composition can have profound effects on cell and tissue function. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties. 相似文献23.
The effect of genetic diversity on angiogenesis 总被引:3,自引:0,他引:3
Angiogenesis is the process by which new blood vessels are formed from existing vessels. Mammalian populations harbor genetic variations that alter angiogenesis. Some of these changes result in Mendelian traits of variable penetrance, with telangiectasia being a common symptom. Other more subtle variations exist, with promoter variations in the VEGF gene being of particular interest. Genetic diversity in angiogenesis-regulating genes has been linked to increased susceptibility to multiple angiogenesis-dependent diseases in humans. These diseases include cancer, arthritis, atherosclerosis, and cardiovascular disease, endometriosis, diabetic retinopathy, retinopathy of prematurity, psoriasis, and sarcoidosis. Also, multiple disturbances in pregnancy including miscarriage, spontaneous preterm delivery, and severe pre-eclampsia have been linked to alterations in angiogenesis-regulating genes. Present efforts to dissect the complexity of the genetic diversity that regulates angiogenesis have used laboratory animals due to the availability of genome sequence for many species and the ability to perform high volume controlled breeding. Ongoing mapping studies have identified multiple loci that control angiogenic responsiveness in several mouse models. Genetic alterations responsible for discrete angiogenic alterations will then be studied in appropriate mouse disease models. 相似文献
24.
Semaphorins are a large class of proteins that function throughout the nervous system to guide axons. It had previously been shown that Semaphorin 5A (Sema5A) was a bifunctional axon guidance cue for mammalian midbrain neurons. We found that zebrafish sema5A was expressed in myotomes during the period of motor axon outgrowth. To determine whether Sema5A functioned in motor axon guidance, we knocked down Sema5A, which resulted in two phenotypes: a delay in motor axon extension into the ventral myotome and aberrant branching of these motor axons. Both phenotypes were rescued by injection of full-length rat Sema5A mRNA. However, adding back RNA encoding the sema domain alone significantly rescued the branching phenotype in sema5A morphants. Conversely, adding back RNA encoding the thrombospondin repeat (TSR) domain alone into sema5A morphants exclusively rescued delay in ventral motor axon extension. Together, these data show that Sema5A is a bifunctional axon guidance cue for vertebrate motor axons in vivo. The TSR domain promotes growth of developing motor axons into the ventral myotome whereas the sema domain mediates repulsion and keeps these motor axons from branching into surrounding myotome regions. 相似文献
25.
Adiponectin is a fat cell-secreted hormone with antidiabetic and anti-inflammatory activities. The reduced adiponectin levels are associated with obesity-related metabolic syndrome. Replenishment of this hormone into animal models can improve insulin sensitivity, decrease blood glucose and lipid levels, and prevent the development of atherosclerosis and fatty liver injury. Despite these findings, the underlying molecular mechanisms remain largely unknown. Here, we have used affinity chromatography to purify the protein complexes that are associated with adiponectin in human serum. The nature of these adiponectin-binding proteins was analyzed by MS/MS. Eight proteins from the adiponectin-containing protein mixtures have been identified. Many of them, including thrombospondin-1 (TSP-1), histidine-rich glycoprotein, kininogen 1, and alpha 2 macroglobulin (alpha2M), are well-known glycoproteins involved in the regulation of inflammation, angiogenesis, and tissue remodeling. Coimmunoprecipitation and radioligand competitive-binding assays confirmed the direct interactions between adiponectin and alpha2M, or TSP-1. Moreover, these specific bindings were also detected in the serum samples derived from both healthy human subjects and patients with type 2 diabetes. In summary, our study demonstrated that, in the circulation, adiponectin forms protein complexes with other serum proteins. These proteins might serve as the physiological-binding partners of adiponectin and regulate its bioavailability and biological activities. 相似文献
26.
Floquet N Dedieu S Martiny L Dauchez M Perahia D 《Archives of biochemistry and biophysics》2008,478(1):103-109
Thrombospondin-1 (TSP-1) interaction with the membranous receptor CD-47 involves the peptide RFYVVMWK (4N-1) located in its C-terminal domain. However, the available X-ray structure of TSP-1 describes this peptide as completely buried into a hydrophobic pocket, preventing any interaction. Where classical standard methods failed, an appropriate approach combining normal mode analysis and an adapted protocol of energy minimization identified the large amplitude motions responsible of the partial solvent exposure of 4N-1. In agreement, the obtained model of the open TSP-1 was further used for protein-protein docking experiments against a homology model generated for CD-47. Considering the multiple applications of the CD-47 receptor as a target, our results open new pharmacological perspectives for the design of TSP-1:CD-47 inhibitors and CD-47 antagonists. We also suggest a common opening mechanism for proteins sharing the same fold as TSP-1. This work also suggests the usefulness of our approach in other topics in which predictions of protein-protein interactions are of importance. 相似文献
27.
Meiniel O Meiniel R Lalloué F Didier R Jauberteau MO Meiniel A Petit D 《Journal of molecular evolution》2008,66(1):1-10
Subcommissural organ (SCO)-spondin is a giant glycoprotein of more than 5000 amino acids found in Vertebrata, expressed in
the central nervous system and constitutive of Reissner’s fiber. For the first time, in situ hybridization performed on zebrafish
(Danio rerio) embryos shows that the gene encoding this protein is expressed transitionally in the floor plate, the ventral midline of
the neural tube, and later in the diencephalic third ventricle roof, the SCO. The modular organization of the protein in Echinodermata
(Strongylocentrotus
purpuratus), Urochordata (Ciona
savignyi and C.
intestinalis), and Vertebrata (Teleostei, Amphibia, Aves and Mammalia) is also described. As the thrombospondin type 1 repeat motifs represent
an increasingly large part of the protein during Deuterostomia evolution, the duplication mechanisms leading to this complex
organization are examined. The functional significance of the particularly well-preserved arrangement of the series of SCO-spondin
repeat motifs and thombospondin type 1 repeats is discussed.
Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
28.
29.
Terskikh Alexey V. Potekhin Sergey A. Melnik Tatiana N. Kajava Andrey V. 《International journal of peptide research and therapeutics》1997,4(4-6):297-304
Summary The assembly domain of cartilage oligomeric matrix protein (COMP) forms an α-helical coiled coil homopentamer with a conserved
polar glutamine in the interior (d) position. We substituted Gln54 for apolar Leu in the recombinant fragment of the rat COMP domain. Biochemical studies and circular dichroism (CD) spectroscopy
showed that the mutant, similarly to the wild-type (w.t.) peptide, forms spontaneously an α-helical pentamer. Thermal transitions
of the w.t. and mutant pentamers were analyzed by CD spectroscopy and differential scanning calorimetry. The Gln54Leu mutation increased the thermal stability of the pentamer with reduced disulfide bonds from 73°C to 104°C. The denaturation
of the disulfide bonded w.t. pentamer was observed at 108°C while the mutant pentamer cannot be denatured up to 120°C (the
apparatus limit). Thus, by Gln54Leu mutation we found a way to significantly stabilize the coiled coil pentamer, making this peptide even more attractive
as an oligomerization tool for various biotechnological applications. 相似文献
30.
Tara Bancroft Mohamed Bouaouina Sophia Roberts Monica Lee David A. Calderwood Martin Schwartz Michael Simons William C. Sessa Themis R. Kyriakides 《The Journal of biological chemistry》2015,290(1):409-422
Vascular remodeling is essential for tissue repair and is regulated by multiple factors, including thrombospondin-2 (TSP2) and hypoxia/VEGF-induced activation of Akt. In contrast to TSP2 knock-out (KO) mice, Akt1 KO mice have elevated TSP2 expression and delayed tissue repair. To investigate the contribution of increased TSP2 to Akt1 KO mice phenotypes, we generated Akt1/TSP2 double KO (DKO) mice. Full-thickness excisional wounds in DKO mice healed at an accelerated rate when compared with Akt1 KO mice. Isolated dermal Akt1 KO fibroblasts expressed increased TSP2 and displayed altered morphology and defects in migration and adhesion. These defects were rescued in DKO fibroblasts or after TSP2 knockdown. Conversely, the addition of exogenous TSP2 to WT cells induced cell morphology and migration rates that were similar to those of Akt1 KO cells. Akt1 KO fibroblasts displayed reduced adhesion to fibronectin with manganese stimulation when compared with WT and DKO cells, revealing an Akt1-dependent role for TSP2 in regulating integrin-mediated adhesions; however, this effect was not due to changes in β1 integrin surface expression or activation. Consistent with these results, Akt1 KO fibroblasts displayed reduced Rac1 activation that was dependent upon expression of TSP2 and could be rescued by a constitutively active Rac mutant. Our observations show that repression of TSP2 expression is a critical aspect of Akt1 function in tissue repair. 相似文献