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David D. Roberts - One of the best experts on this subject based on the ideXlab platform.
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THBS1 (Thrombospondin-1).
Atlas of genetics and cytogenetics in oncology and haematology, 2020Co-Authors: Jeffrey S. Isenberg, David D. RobertsAbstract:Thrombospondins are encoded in vertebrates by a family of 5 THBS genes. THBS1 is infrequently mutated in most cancers, but its expression is positively regulated by several tumor suppressor genes and negatively regulated by activated oncogenes and promoter hypermethylation. Consequently, Thrombospondin-1 expression is frequently lost during oncogenesis and is correlated with a poor prognosis for some cancers. Thrombospondin-1 is a secreted protein that acts in the tumor microenvironment to inhibit angiogenesis, regulate antitumor immunity, stimulate tumor cell migration, and regulate the activities of extracellular proteases and growth factors. Differential effects of Thrombospondin-1 on the sensitivity of normal versus malignant cells to ischemic and genotoxic stress also regulate the responses to tumors to therapeutic radiation and chemotherapy.
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Thrombospondin 1 and cd47 signaling regulate healing of thermal injury in mice
Matrix Biology, 2014Co-Authors: David R Sotopantoja, Justin B. Maxhimer, Jeffrey S. Isenberg, A Ghosh, Hubert B Shih, Katherine L Cook, David D. RobertsAbstract:More than 2.5 million Americans suffer from burn injuries annually, and burn management is a major public health problem. Treatments have been developed to manage wound injuries employing skin grafts, various dressings and topical and systemic agents. However, these often achieve limited degrees of success. We previously reported that targeting the interaction of Thrombospondin-1 with its signaling receptor CD47 or deletion of the genes encoding either of these proteins in mice improves recovery from soft tissue ischemic injuries as well as tissue injuries caused by ionizing radiation. We now demonstrate that the absence of CD47 improves the rate of wound closure for a focal dermal second-degree thermal injury, whereas lack of Thrombospondin-1 initially delays wound closure compared to healing in wild type mice. Doppler analysis of the wounded area showed increased blood flow in both CD47 and Thrombospondin-1 null mice. Accelerated wound closure in the CD47 null mice was associated with increased fibrosis as demonstrated by a 4-fold increase in collagen fraction. Wound tissue of CD47 null mice showed increased Thrombospondin-1 mRNA and protein expression and TGF-β1 mRNA levels. Activation of latent TGF-β1 was increased in thermally injured CD47-null tissue as assessed by phosphorylation of the TGF-β1 receptor-regulated transcription factors SMAD-2 and -3. Overall these results indicate that targeting CD47 may improve the speed of healing thermal injuries, but some level of CD47 expression may be required to limit the long term TGF-β1-dependent fibrosis of these wounds.
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endogenous Thrombospondin 1 regulates leukocyte recruitment and activation and accelerates death from systemic candidiasis
PLOS ONE, 2012Co-Authors: Gema Martinmanso, Maria Tsokos, Svetlana A. Kuznetsova, Dhammika H M L P Navarathna, Susana Galli, David R Sotopantoja, David D. RobertsAbstract:Disseminated Candida albicans infection results in high morbidity and mortality despite treatment with existing antifungal drugs. Recent studies suggest that modulating the host immune response can improve survival, but specific host targets for accomplishing this goal remain to be identified. The extracellular matrix protein Thrombospondin-1 is released at sites of tissue injury and modulates several immune functions, but its role in C. albicans pathogenesis has not been investigated. Here, we show that mice lacking Thrombospondin-1 have an advantage in surviving disseminated candidiasis and more efficiently clear the initial colonization from kidneys despite exhibiting fewer infiltrating leukocytes. By examining local and systemic cytokine responses to C. albicans and other standard inflammatory stimuli, we identify a crucial function of phagocytes in this enhanced resistance. Subcutaneous air pouch and systemic candidiasis models demonstrated that endogenous Thrombospondin-1 enhances the early innate immune response against C. albicans and promotes activation of inflammatory macrophages (inducible nitric oxide synthase+, IL-6high, TNF-αhigh, IL-10low), release of the chemokines MIP-2, JE, MIP-1α, and RANTES, and CXCR2-driven polymorphonuclear leukocytes recruitment. However, Thrombospondin-1 inhibited the phagocytic capacity of inflammatory leukocytes in vivo and in vitro, resulting in increased fungal burden in the kidney and increased mortality in wild type mice. Thus, Thrombospondin-1 enhances the pathogenesis of disseminated candidiasis by creating an imbalance in the host immune response that ultimately leads to reduced phagocytic function, impaired fungal clearance, and increased mortality. Conversely, inhibitors of Thrombospondin-1 may be useful drugs to improve patient recovery from disseminated candidiasis.
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The matricellular protein Thrombospondin-1 globally regulates cardiovascular function and responses to stress via CD47
Matrix biology : journal of the International Society for Matrix Biology, 2012Co-Authors: David D. Roberts, Thomas W. Miller, Natasha M. Rogers, Mingyi Yao, Jeffrey S. IsenbergAbstract:Matricellular proteins play diverse roles in modulating cell behavior by engaging specific cell surface receptors and interacting with extracellular matrix proteins, secreted enzymes, and growth factors. Studies of such interactions involving Thrombospondin-1 have revealed several physiological functions and roles in the pathogenesis of injury responses and cancer, but the relatively mild phenotypes of mice lacking Thrombospondin-1 suggested that Thrombospondin-1 would not be a central player that could be exploited therapeutically. Recent research focusing on signaling through its receptor CD47, however, has uncovered more critical roles for Thrombospondin-1 in acute regulation of cardiovascular dynamics, hemostasis, immunity, and mitochondrial homeostasis. Several of these functions are mediated by potent and redundant inhibition of the canonical nitric oxide pathway. Conversely, elevated tissue Thrombospondin-1 levels in major chronic diseases of aging may account for the deficient nitric oxide signaling that characterizes these diseases, and experimental therapeutics targeting CD47 show promise for treating such chronic diseases as well as acute stress conditions that are associated with elevated Thrombospondin-1 expression.
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Regulation of nitric oxide signalling by Thrombospondin 1: implications for anti-angiogenic therapies
Nature reviews. Cancer, 2009Co-Authors: Jeffrey S. Isenberg, Justin B. Maxhimer, Gema Martin-manso, David D. RobertsAbstract:In addition to long-term regulation of angiogenesis, angiogenic growth factor signalling through nitric oxide (NO) acutely controls blood flow and haemostasis. Inhibition of this pathway may account for the hypertensive and pro-thrombotic side effects of the vascular endothelial growth factor antagonists that are currently used for cancer treatment. The first identified endogenous angiogenesis inhibitor, Thrombospondin 1, also controls tissue perfusion, haemostasis and radiosensitivity by antagonizing NO signalling. We examine the role of these and other emerging activities of Thrombospondin 1 in cancer. Clarifying how endogenous and therapeutic angiogenesis inhibitors regulate vascular NO signalling could facilitate development of more selective inhibitors.
Eiji Kusano - One of the best experts on this subject based on the ideXlab platform.
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spironolactone suppresses peritubular capillary loss and prevents deoxycorticosterone acetate salt induced tubulointerstitial fibrosis
Hypertension, 2008Co-Authors: Yoshitaka Iwazu, Genro Fujisawa, Eiko Nakazawa, Shigeaki Muto, Shun Ishibashi, Koji Okada, Eiji KusanoAbstract:We examined whether and how peritubular capillary (PTC) loss in the renal cortex contributes to the development of deoxycorticosterone acetate (DOCA)/salt-induced tubulointerstitial fibrosis. Uninephrectomized rats provided with 0.9% NaCl/0.3% KCl drinking solution ad libitum were divided into control, DOCA, and spironolactone groups, which were administered vehicle, DOCA alone, and DOCA plus spironolactone for 1 (initial phase) and 4 weeks (delayed phase), respectively. Exposure to DOCA initiated a sequence of events that initially involved reduced PTC density, followed by a delayed response that involved further reduced PTC density, development of tubulointerstitial fibrosis and hypertension, enhanced expression of transforming growth factor-β1 and connective tissue growth factor, and impaired renal function. Concomitant with the reduced PTC density, the 2 hypoxia-responsive angiogenic factors (vascular endothelial growth factor and hypoxia-inducible factor-1α) and the antiangiogenic factor (Thrombospondin-1) were upregulated in cortical tubular cells of the DOCA group during the 2 phases and only in the delayed phase, respectively. In the DOCA group, PTC endothelial cell apoptosis was enhanced during the 2 phases, and PTC endothelial cell proliferation was inhibited in the delayed phase. In accordance with upregulation of Thrombospondin-1, p53 expression was enhanced in the DOCA group in the delayed phase. The initial and delayed effects of DOCA were blocked in the spironolactone group. We conclude that exposure to DOCA initially caused the reduced PTC density associated with enhanced apoptosis independent of Thrombospondin-1, which induced tubulointerstitial fibrosis via p53-mediated Thrombospondin-1 activation, and spironolactone conversely corrected the effects of DOCA to prevent fibrosis.
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spironolactone suppresses peritubular capillary loss and prevents deoxycorticosterone acetate salt induced tubulointerstitial fibrosis
Hypertension, 2008Co-Authors: Yoshitaka Iwazu, Genro Fujisawa, Eiko Nakazawa, Shigeaki Muto, Shun Ishibashi, Koji Okada, Eiji KusanoAbstract:We examined whether and how peritubular capillary (PTC) loss in the renal cortex contributes to the development of deoxycorticosterone acetate (DOCA)/salt-induced tubulointerstitial fibrosis. Uninephrectomized rats provided with 0.9% NaCl/0.3% KCl drinking solution ad libitum were divided into control, DOCA, and spironolactone groups, which were administered vehicle, DOCA alone, and DOCA plus spironolactone for 1 (initial phase) and 4 weeks (delayed phase), respectively. Exposure to DOCA initiated a sequence of events that initially involved reduced PTC density, followed by a delayed response that involved further reduced PTC density, development of tubulointerstitial fibrosis and hypertension, enhanced expression of transforming growth factor-beta1 and connective tissue growth factor, and impaired renal function. Concomitant with the reduced PTC density, the 2 hypoxia-responsive angiogenic factors (vascular endothelial growth factor and hypoxia-inducible factor-1alpha) and the antiangiogenic factor (Thrombospondin-1) were upregulated in cortical tubular cells of the DOCA group during the 2 phases and only in the delayed phase, respectively. In the DOCA group, PTC endothelial cell apoptosis was enhanced during the 2 phases, and PTC endothelial cell proliferation was inhibited in the delayed phase. In accordance with upregulation of Thrombospondin-1, p53 expression was enhanced in the DOCA group in the delayed phase. The initial and delayed effects of DOCA were blocked in the spironolactone group. We conclude that exposure to DOCA initially caused the reduced PTC density associated with enhanced apoptosis independent of Thrombospondin-1, which induced tubulointerstitial fibrosis via p53-mediated Thrombospondin-1 activation, and spironolactone conversely corrected the effects of DOCA to prevent fibrosis.
Douglas S Annis - One of the best experts on this subject based on the ideXlab platform.
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Thrombospondin-1 (TSP1) Contributes to the Development of Vascular Inflammation by Regulating Monocytic Cell Motility in Mouse Models of Abdominal Aortic Aneurysm
Circulation research, 2015Co-Authors: Zhenjie Liu, Deane F. Mosher, Douglas S Annis, Jing Zhang, Stephanie Morgan, Jun Ren, Qiwei Wang, Christine M. Sorenson, Nader Sheibani, Bo LiuAbstract:Rationale:Histological examination of abdominal aortic aneurysm (AAA) tissues demonstrates extracellular matrix destruction and infiltration of inflammatory cells. Previous work with mouse models of AAA has shown that anti-inflammatory strategies can effectively attenuate aneurysm formation. Thrombospondin-1 is a matricellular protein involved in the maintenance of vascular structure and homeostasis through the regulation of biological functions, such as cell proliferation, apoptosis, and adhesion. Expression levels of Thrombospondin-1 correlate with vascular disease conditions. Objective:To use Thrombospondin-1–deficient (Thbs1−/−) mice to test the hypothesis that Thrombospondin-1 contributes to pathogenesis of AAAs. Methods and Results:Mouse experimental AAA was induced through perivascular treatment with calcium phosphate, intraluminal perfusion with porcine elastase, or systemic administration of angiotensin II. Induction of AAA increased Thrombospondin-1 expression in aortas of C57BL/6 or apoE−/− mic...
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gabapentin receptor α2δ 1 is a neuronal Thrombospondin receptor responsible for excitatory cns synaptogenesis
Cell, 2009Co-Authors: Chandrani Chakraborty, Nicola J Allen, Cagla Eroglu, Michael W Susman, Nancy A Orourke, Engin Ozkan, Sara B Mulinyawe, Chan-young Park, Douglas S AnnisAbstract:Synapses are asymmetric cellular adhesions that are critical for nervous system development and function, but the mechanisms that induce their formation are not well understood. We have previously identified Thrombospondin as an astrocyte-secreted protein that promotes central nervous system (CNS) synaptogenesis. Here, we identify the neuronal Thrombospondin receptor involved in CNS synapse formation as alpha2delta-1, the receptor for the anti-epileptic and analgesic drug gabapentin. We show that the VWF-A domain of alpha2delta-1 interacts with the epidermal growth factor-like repeats common to all Thrombospondins. alpha2delta-1 overexpression increases synaptogenesis in vitro and in vivo and is required postsynaptically for Thrombospondin- and astrocyte-induced synapse formation in vitro. Gabapentin antagonizes Thrombospondin binding to alpha2delta-1 and powerfully inhibits excitatory synapse formation in vitro and in vivo. These findings identify alpha2delta-1 as a receptor involved in excitatory synapse formation and suggest that gabapentin may function therapeutically by blocking new synapse formation.
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gabapentin receptor α2δ 1 is a neuronal Thrombospondin receptor responsible for excitatory cns synaptogenesis
Cell, 2009Co-Authors: Chandrani Chakraborty, Nicola J Allen, Cagla Eroglu, Michael W Susman, Nancy A Orourke, Engin Ozkan, Sara B Mulinyawe, Chan-young Park, Douglas S AnnisAbstract:Summary Synapses are asymmetric cellular adhesions that are critical for nervous system development and function, but the mechanisms that induce their formation are not well understood. We have previously identified Thrombospondin as an astrocyte-secreted protein that promotes central nervous system (CNS) synaptogenesis. Here, we identify the neuronal Thrombospondin receptor involved in CNS synapse formation as α2δ-1, the receptor for the anti-epileptic and analgesic drug gabapentin. We show that the VWF-A domain of α2δ-1 interacts with the epidermal growth factor-like repeats common to all Thrombospondins. α2δ-1 overexpression increases synaptogenesis in vitro and in vivo and is required postsynaptically for Thrombospondin- and astrocyte-induced synapse formation in vitro. Gabapentin antagonizes Thrombospondin binding to α2δ-1 and powerfully inhibits excitatory synapse formation in vitro and in vivo. These findings identify α2δ-1 as a receptor involved in excitatory synapse formation and suggest that gabapentin may function therapeutically by blocking new synapse formation.
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differential interactions of Thrombospondin 1 2 and 4 with cd47 and effects on cgmp signaling and ischemic injury responses
Journal of Biological Chemistry, 2009Co-Authors: Jeff S. Isenberg, Deane F. Mosher, Douglas S Annis, Michael L. Pendrak, William A. Frazier, Malgorzata Ptaszynska, David D. RobertsAbstract:Thrombospondin-1 regulates nitric oxide (NO) signaling in vascular cells via CD47. Because CD47 binding motifs are conserved in the C-terminal signature domains of all five Thrombospondins and indirect evidence has implied CD47 interactions with other family members, we compared activities of recombinant signature domains of Thrombospondin-1, -2, and -4 to interact with CD47 and modulate cGMP signaling. Signature domains of Thrombospondin-2 and -4 were less active than that of Thrombospondin-1 for inhibiting binding of radiolabeled signature domain of Thrombospondin-1 or SIRPα (signal-regulatory protein) to cells expressing CD47. Consistent with this binding selectivity, the signature domain of Thrombospondin-1 was more potent than those of Thrombospondin-2 or -4 for inhibiting NO-stimulated cGMP synthesis in vascular smooth muscle cells and downstream effects on cell adhesion. In contrast to Thrombospondin-1- and CD47-null cells, primary vascular cells from Thrombospondin-2-null mice lack enhanced basal and NO-stimulated cGMP signaling. Effects of endogenous Thrombospondin-2 on NO/cGMP signaling could be detected only in Thrombospondin-1-null cells. Furthermore, tissue survival of ischemic injury and acute recovery of blood flow in Thrombospondin-2-nulls resembles that of wild type mice. Therefore, Thrombospondin-1 is the dominant regulator of NO/cGMP signaling via CD47, and its limiting role in acute ischemic injury responses is not shared by Thrombospondin-2.
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fibroblast growth factor 2 binding to the Thrombospondin 1 type iii repeats a novel antiangiogenic domain
The International Journal of Biochemistry & Cell Biology, 2008Co-Authors: Barbara Margosio, Douglas S Annis, Marco Rusnati, Katiuscia Bonezzi, Blue Leaf A Cordes, Chiara Urbinati, Raffaella Giavazzi, Marco Presta, Domenico Ribatti, Deane F. MosherAbstract:Thrombospondin-1, an antiangiogenic matricellular protein, binds with high affinity to the angiogenic fibroblast growth factor-2, affecting its bioavailability and activity. The present work aimed at further locating the fibroblast growth factor-2 binding site of Thrombospondin-1 and investigating its activity, using recombinant Thrombospondin-1 proteins. Only recombinant constructs containing the Thrombospondin-1 type III repeats bound fibroblast growth factor-2, whereas other domains, including the known anti-angiogenic type I repeats, were inactive. Binding was specific and inhibited by the anti Thrombospondin-1 monoclonal antibody B5.2. Surface plasmon resonance analysis on BIAcore revealed a binding affinity (Kd) of 310 nM for the type III repeats and 11 nM for intact Thrombospondin-1. Since the type III repeats bind calcium, the effect of calcium on Thrombospondin-1 binding to fibroblast growth factor-2 was investigated. Binding was modulated by calcium, as Thrombospondin-1 or the type III repeats bound to fibroblast growth factor-2 only in calcium concentrations <0.3 mM. The type III repeats inhibited binding of fibroblast growth factor-2 to endothelial cells, fibroblast growth factor-2-induced endothelial cell proliferation in vitro and angiogenesis in the chorioallantoic membrane assay in vivo, thus indicating the antiangiogenic activity of the domain. In conclusion, this study demonstrates that the fibroblast growth factor-2 binding site of Thrombospondin-1 is located in the type III repeats. The finding that this domain is active in inhibiting angiogenesis indicates that the type III repeats represent a novel antiangiogenic domain of Thrombospondin-1.
Deane F. Mosher - One of the best experts on this subject based on the ideXlab platform.
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Thrombospondin-1 (TSP1) Contributes to the Development of Vascular Inflammation by Regulating Monocytic Cell Motility in Mouse Models of Abdominal Aortic Aneurysm
Circulation research, 2015Co-Authors: Zhenjie Liu, Deane F. Mosher, Douglas S Annis, Jing Zhang, Stephanie Morgan, Jun Ren, Qiwei Wang, Christine M. Sorenson, Nader Sheibani, Bo LiuAbstract:Rationale:Histological examination of abdominal aortic aneurysm (AAA) tissues demonstrates extracellular matrix destruction and infiltration of inflammatory cells. Previous work with mouse models of AAA has shown that anti-inflammatory strategies can effectively attenuate aneurysm formation. Thrombospondin-1 is a matricellular protein involved in the maintenance of vascular structure and homeostasis through the regulation of biological functions, such as cell proliferation, apoptosis, and adhesion. Expression levels of Thrombospondin-1 correlate with vascular disease conditions. Objective:To use Thrombospondin-1–deficient (Thbs1−/−) mice to test the hypothesis that Thrombospondin-1 contributes to pathogenesis of AAAs. Methods and Results:Mouse experimental AAA was induced through perivascular treatment with calcium phosphate, intraluminal perfusion with porcine elastase, or systemic administration of angiotensin II. Induction of AAA increased Thrombospondin-1 expression in aortas of C57BL/6 or apoE−/− mic...
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differential interactions of Thrombospondin 1 2 and 4 with cd47 and effects on cgmp signaling and ischemic injury responses
Journal of Biological Chemistry, 2009Co-Authors: Jeff S. Isenberg, Deane F. Mosher, Douglas S Annis, Michael L. Pendrak, William A. Frazier, Malgorzata Ptaszynska, David D. RobertsAbstract:Thrombospondin-1 regulates nitric oxide (NO) signaling in vascular cells via CD47. Because CD47 binding motifs are conserved in the C-terminal signature domains of all five Thrombospondins and indirect evidence has implied CD47 interactions with other family members, we compared activities of recombinant signature domains of Thrombospondin-1, -2, and -4 to interact with CD47 and modulate cGMP signaling. Signature domains of Thrombospondin-2 and -4 were less active than that of Thrombospondin-1 for inhibiting binding of radiolabeled signature domain of Thrombospondin-1 or SIRPα (signal-regulatory protein) to cells expressing CD47. Consistent with this binding selectivity, the signature domain of Thrombospondin-1 was more potent than those of Thrombospondin-2 or -4 for inhibiting NO-stimulated cGMP synthesis in vascular smooth muscle cells and downstream effects on cell adhesion. In contrast to Thrombospondin-1- and CD47-null cells, primary vascular cells from Thrombospondin-2-null mice lack enhanced basal and NO-stimulated cGMP signaling. Effects of endogenous Thrombospondin-2 on NO/cGMP signaling could be detected only in Thrombospondin-1-null cells. Furthermore, tissue survival of ischemic injury and acute recovery of blood flow in Thrombospondin-2-nulls resembles that of wild type mice. Therefore, Thrombospondin-1 is the dominant regulator of NO/cGMP signaling via CD47, and its limiting role in acute ischemic injury responses is not shared by Thrombospondin-2.
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mutations targeting intermodular interfaces or calcium binding destabilize the Thrombospondin 2 signature domain
Journal of Biological Chemistry, 2008Co-Authors: Britt C Carlson, Kristin A Gunderson, Deane F. MosherAbstract:Thrombospondins (THBSs) are a family of secreted calcium-binding glycoproteins with roles in angiogenesis, cell motility, apoptosis, cytoskeletal organization, and extracellular matrix organization. The THBS-2 signature domain (three epidermal growth factor (EGF)-like modules, a wire module with 13 calcium-binding repeats, and a lectin-like module) binds 30 calcium ions and forms extensive interactions among its parts. We explored the significance of these structural elements by examining the impact of 10 different mutations known to result in pseudoachondrodysplasia or multiple epiphyseal dysplasia when found in the homologous wire and lectin-like modules of Thrombospondin-5 (THBS-5). A variety of observations indicate that the mutations result in unstable THBS-5 proteins that aggregate in the endoplasmic reticulum. We introduced the mutations into homologous sites of a THBS-2 construct, for which the crystal structure is known, and determined the effects of the mutations on structure as assayed by differential scanning calorimetry and expression of the epitope for the 4B6.13 conformation-sensitive antibody. Abnormalities were found in one or more of several readouts: stability of interactions between the wire and lectin-like modules, stabilities of the EGF-like and wire modules, expression of the 4B6.13 epitope in soluble protein, and expression of the 4B6.13 epitope in substrate-adsorbed protein at different calcium concentrations. The patterns of abnormalities support the idea that the EGF-like, wire, and lectin-like modules constitute a dynamic and interactive calcium-sensitive structure in which a distortion at one site is transmitted to distal sites, leading to global changes in the protein.
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fibroblast growth factor 2 binding to the Thrombospondin 1 type iii repeats a novel antiangiogenic domain
The International Journal of Biochemistry & Cell Biology, 2008Co-Authors: Barbara Margosio, Douglas S Annis, Marco Rusnati, Katiuscia Bonezzi, Blue Leaf A Cordes, Chiara Urbinati, Raffaella Giavazzi, Marco Presta, Domenico Ribatti, Deane F. MosherAbstract:Thrombospondin-1, an antiangiogenic matricellular protein, binds with high affinity to the angiogenic fibroblast growth factor-2, affecting its bioavailability and activity. The present work aimed at further locating the fibroblast growth factor-2 binding site of Thrombospondin-1 and investigating its activity, using recombinant Thrombospondin-1 proteins. Only recombinant constructs containing the Thrombospondin-1 type III repeats bound fibroblast growth factor-2, whereas other domains, including the known anti-angiogenic type I repeats, were inactive. Binding was specific and inhibited by the anti Thrombospondin-1 monoclonal antibody B5.2. Surface plasmon resonance analysis on BIAcore revealed a binding affinity (Kd) of 310 nM for the type III repeats and 11 nM for intact Thrombospondin-1. Since the type III repeats bind calcium, the effect of calcium on Thrombospondin-1 binding to fibroblast growth factor-2 was investigated. Binding was modulated by calcium, as Thrombospondin-1 or the type III repeats bound to fibroblast growth factor-2 only in calcium concentrations <0.3 mM. The type III repeats inhibited binding of fibroblast growth factor-2 to endothelial cells, fibroblast growth factor-2-induced endothelial cell proliferation in vitro and angiogenesis in the chorioallantoic membrane assay in vivo, thus indicating the antiangiogenic activity of the domain. In conclusion, this study demonstrates that the fibroblast growth factor-2 binding site of Thrombospondin-1 is located in the type III repeats. The finding that this domain is active in inhibiting angiogenesis indicates that the type III repeats represent a novel antiangiogenic domain of Thrombospondin-1.
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biophysical characterization of the signature domains of Thrombospondin 4 and Thrombospondin 2
Journal of Biological Chemistry, 2005Co-Authors: Tina M. Misenheimer, Deane F. MosherAbstract:Abstract The signature domain of Thrombospondins consists of tandem epidermal growth factor-like modules, 13 calcium-binding repeats, and a lectin-like module. Although very similar, the signature domains of Thrombospondin-1 and -2 differ in several potentially important ways from the domains of Thrombospondin-3, -4, and -5. We have compared matching recombinant segments representing the signature domains of Thrombospondin-2 and -4. In the presence of 2 mm CaCl2, the far UV circular dichroism spectra of Thrombospondin-2 and -4 constructs contain a strong negative band at 202 nm, but only the Thrombospondin-2 construct has a band at 216 nm. Chelation of calcium shifted the negative bands to lower magnitudes. Titrations of the spectra demonstrated lower cooperativity and affinity for binding of calcium to Thrombospondin-4 compared with Thrombospondin-2. Atomic absorption spectroscopy demonstrated that the Thrombospondin-4 constructs bind seven less calcium than the Thrombospondin-2 construct at 0.6 mm CaCl2. In 2 mm CaCl2, the near UV circular dichroism spectra of Thrombospondin-2, but not Thrombospondin-4, contain a positive band at 292 nm that disappears upon calcium chelation. Intrinsic fluorescence spectra for both proteins were also sensitive to calcium, but the changes were simpler and more marked for Thrombospondin-2 than for Thrombospondin-4. In differential scanning calorimetry, the Thrombospondin-2 construct melted in two distinct transitions at 53.5 and 81.8 °C, whereas the first transition for Thrombospondin-4 constructs was observed at 63.5 °C. Thus, the studies revealed significant differences between the signature domains of Thrombospondin-2 and Thrombospondin-4 in calcium binding, fine structure, and inter-modular interactions.
Yoshitaka Iwazu - One of the best experts on this subject based on the ideXlab platform.
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spironolactone suppresses peritubular capillary loss and prevents deoxycorticosterone acetate salt induced tubulointerstitial fibrosis
Hypertension, 2008Co-Authors: Yoshitaka Iwazu, Genro Fujisawa, Eiko Nakazawa, Shigeaki Muto, Shun Ishibashi, Koji Okada, Eiji KusanoAbstract:We examined whether and how peritubular capillary (PTC) loss in the renal cortex contributes to the development of deoxycorticosterone acetate (DOCA)/salt-induced tubulointerstitial fibrosis. Uninephrectomized rats provided with 0.9% NaCl/0.3% KCl drinking solution ad libitum were divided into control, DOCA, and spironolactone groups, which were administered vehicle, DOCA alone, and DOCA plus spironolactone for 1 (initial phase) and 4 weeks (delayed phase), respectively. Exposure to DOCA initiated a sequence of events that initially involved reduced PTC density, followed by a delayed response that involved further reduced PTC density, development of tubulointerstitial fibrosis and hypertension, enhanced expression of transforming growth factor-β1 and connective tissue growth factor, and impaired renal function. Concomitant with the reduced PTC density, the 2 hypoxia-responsive angiogenic factors (vascular endothelial growth factor and hypoxia-inducible factor-1α) and the antiangiogenic factor (Thrombospondin-1) were upregulated in cortical tubular cells of the DOCA group during the 2 phases and only in the delayed phase, respectively. In the DOCA group, PTC endothelial cell apoptosis was enhanced during the 2 phases, and PTC endothelial cell proliferation was inhibited in the delayed phase. In accordance with upregulation of Thrombospondin-1, p53 expression was enhanced in the DOCA group in the delayed phase. The initial and delayed effects of DOCA were blocked in the spironolactone group. We conclude that exposure to DOCA initially caused the reduced PTC density associated with enhanced apoptosis independent of Thrombospondin-1, which induced tubulointerstitial fibrosis via p53-mediated Thrombospondin-1 activation, and spironolactone conversely corrected the effects of DOCA to prevent fibrosis.
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spironolactone suppresses peritubular capillary loss and prevents deoxycorticosterone acetate salt induced tubulointerstitial fibrosis
Hypertension, 2008Co-Authors: Yoshitaka Iwazu, Genro Fujisawa, Eiko Nakazawa, Shigeaki Muto, Shun Ishibashi, Koji Okada, Eiji KusanoAbstract:We examined whether and how peritubular capillary (PTC) loss in the renal cortex contributes to the development of deoxycorticosterone acetate (DOCA)/salt-induced tubulointerstitial fibrosis. Uninephrectomized rats provided with 0.9% NaCl/0.3% KCl drinking solution ad libitum were divided into control, DOCA, and spironolactone groups, which were administered vehicle, DOCA alone, and DOCA plus spironolactone for 1 (initial phase) and 4 weeks (delayed phase), respectively. Exposure to DOCA initiated a sequence of events that initially involved reduced PTC density, followed by a delayed response that involved further reduced PTC density, development of tubulointerstitial fibrosis and hypertension, enhanced expression of transforming growth factor-beta1 and connective tissue growth factor, and impaired renal function. Concomitant with the reduced PTC density, the 2 hypoxia-responsive angiogenic factors (vascular endothelial growth factor and hypoxia-inducible factor-1alpha) and the antiangiogenic factor (Thrombospondin-1) were upregulated in cortical tubular cells of the DOCA group during the 2 phases and only in the delayed phase, respectively. In the DOCA group, PTC endothelial cell apoptosis was enhanced during the 2 phases, and PTC endothelial cell proliferation was inhibited in the delayed phase. In accordance with upregulation of Thrombospondin-1, p53 expression was enhanced in the DOCA group in the delayed phase. The initial and delayed effects of DOCA were blocked in the spironolactone group. We conclude that exposure to DOCA initially caused the reduced PTC density associated with enhanced apoptosis independent of Thrombospondin-1, which induced tubulointerstitial fibrosis via p53-mediated Thrombospondin-1 activation, and spironolactone conversely corrected the effects of DOCA to prevent fibrosis.
