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David J. Weber - One of the best experts on this subject based on the ideXlab platform.
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Model for S100B-dependent inhibition of IL6/STAT3 signaling and its possible role in the pathology of malignant melanoma.
'Public Library of Science (PLoS)', 2021Co-Authors: Milad J Alasady, Paul T. Wilder, David J. Weber, Adam D Pierce, Michael C Cavalier, Alexander R. Terry, Catherine S. Blaha, Kaylin A. Adipietro, Nissim HayAbstract:(A) Elevated levels of S100B found in most melanoma binds RSK in a calcium-dependent manner and sterically prevents its ERK-dependent phosphorylation at T573, which is needed for RSK nuclear localization (8). As a result, it is proposed here that elevated S100B inhibits expression and secretion of IL6 and phosphorylation and transcriptional activity of STAT3 (Figs 1–4). S100B-dependent inhibition of IL6 and STAT3 phosphorylation is via RSK (Fig 5). S100B also inhibits phosphorylation of CREB in the nucleus. Given that S100B forms a complex with RSK and prevents RSK nuclear localization, it is proposed that S100B inhibits phosphorylation of CREB in the nucleus via RSK (Fig 6). Thus, CREB-dependent expression of IL6 is inhibited, as is IL6/STAT3 signaling. (B) During early stages of melanoma progression, it is hypothesized that IL6 induces anti-proliferative mechanism to inhibit the progression of melanoma. Thus, when S100B levels elevate to a critical threshold in a pre-metastatic state, it blocks IL6 expression and initiates the transition of melanoma from pre-malignant to a malignant form.
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novel protein inhibitor interactions in site 3 of ca 2 bound S100B as discovered by x ray crystallography
Acta Crystallographica Section D-biological Crystallography, 2016Co-Authors: Michael C Cavalier, Paul T. Wilder, Adam D Pierce, Alexander D. Mackerell, Zephan Melville, E Aligholizadeh, E P Raman, Lei Fang, Milad J Alasady, David J. WeberAbstract:Structure-based drug discovery is under way to identify and develop small-molecule S100B inhibitors (SBiXs). Such inhibitors have therapeutic potential for treating malignant melanoma, since high levels of S100B downregulate wild-type p53 tumor suppressor function in this cancer. Computational and X-ray crystallographic studies of two S100B-SBiX complexes are described, and both compounds (apomorphine hydrochloride and ethidium bromide) occupy an area of the S100B hydrophobic cleft which is termed site 3. These data also reveal novel protein-inhibitor interactions which can be used in future drug-design studies to improve SBiX affinity and specificity. Of particular interest, apomorphine hydrochloride showed S100B-dependent killing in melanoma cell assays, although the efficacy exceeds its affinity for S100B and implicates possible off-target contributions. Because there are no structural data available for compounds occupying site 3 alone, these studies contribute towards the structure-based approach to targeting S100B by including interactions with residues in site 3 of S100B.
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the calcium dependent interaction of S100B with its protein targets
Cardiovascular Psychiatry and Neurology, 2010Co-Authors: Danna B Zimmer, David J. WeberAbstract:S100B is a calcium signaling protein that is a member of the S100 protein family. An important feature of S100B and most other S100 proteins (S100s) is that they often bind Ca(2+) ions relatively weakly in the absence of a protein target; upon binding their target proteins, Ca(2+)-binding then increases by as much as from 200- to 400-fold. This manuscript reviews the structural basis and physiological significance of increased Ca(2+)-binding affinity in the presence of protein targets. New information regarding redundancy among family members and the structural domains that mediate the interaction of S100B, and other S100s, with their targets is also presented. It is the diversity among individual S100s, the protein targets that they interact with, and the Ca(2+) dependency of these protein-protein interactions that allow S100s to transduce changes in [Ca(2+)](intracellular) levels into spatially and temporally unique biological responses.
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The calcium-binding protein S100B down-regulates p53 and apoptosis in malignant melanoma.
The Journal of biological chemistry, 2010Co-Authors: Jing Lin, Paul T. Wilder, Qingyuan Yang, David J. WeberAbstract:The S100B-p53 protein complex was discovered in C8146A malignant melanoma, but the consequences of this interaction required further study. When S100B expression was inhibited in C8146As by siRNA (siRNA(S100B)), wt p53 mRNA levels were unchanged, but p53 protein, phosphorylated p53, and p53 gene products (i.e. p21 and PIDD) were increased. siRNA(S100B) transfections also restored p53-dependent apoptosis in C8146As as judged by poly(ADP-ribose) polymerase cleavage, DNA ladder formation, caspase 3 and 8 activation, and aggregation of the Fas death receptor (+UV); whereas, siRNA(S100B) had no effect in SK-MEL-28 cells containing elevated S100B and inactive p53 (p53R145L mutant). siRNA(S100B)-mediated apoptosis was independent of the mitochondria, because no changes were observed in mitochondrial membrane potential, cytochrome c release, caspase 9 activation, or ratios of pro- and anti-apoptotic proteins (BAX, Bcl-2, and Bcl-X(L)). As expected, cells lacking S100B (LOX-IM VI) were not affected by siRNA(S100B), and introduction of S100B reduced their UV-induced apoptosis activity by 7-fold, further demonstrating that S100B inhibits apoptosis activities in p53-containing cells. In other wild-type p53 cells (i.e. C8146A, UACC-2571, and UACC-62), S100B was found to contribute to cell survival after UV treatment, and for C8146As, the decrease in survival after siRNA(S100B) transfection (+UV) could be reversed by the p53 inhibitor, pifithrin-alpha. In summary, reducing S100B expression with siRNA was sufficient to activate p53, its transcriptional activation activities, and p53-dependent apoptosis pathway(s) in melanoma involving the Fas death receptor and perhaps PIDD. Thus, a well known marker for malignant melanoma, S100B, likely contributes to cancer progression by down-regulating the tumor suppressor protein, p53.
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the effects of capz peptide trtk 12 binding to S100B ca2 as examined by nmr and x ray crystallography
Journal of Molecular Biology, 2010Co-Authors: Thomas H. Charpentier, Paul T. Wilder, Melissa A. Liriano, Kristen M. Varney, Eric A. Toth, Laura E Thompson, Edwin Pozharski, David J. WeberAbstract:Structure-based drug design is underway to inhibit the S100B-p53 interaction as a strategy for treating malignant melanoma. X-ray crystallography was used here to characterize an interaction between Ca(2)(+)-S100B and TRTK-12, a target that binds to the p53-binding site on S100B. The structures of Ca(2+)-S100B (1.5-A resolution) and S100B-Ca(2)(+)-TRTK-12 (2.0-A resolution) determined here indicate that the S100B-Ca(2+)-TRTK-12 complex is dominated by an interaction between Trp7 of TRTK-12 and a hydrophobic binding pocket exposed on Ca(2+)-S100B involving residues in helices 2 and 3 and loop 2. As with an S100B-Ca(2)(+)-p53 peptide complex, TRTK-12 binding to Ca(2+)-S100B was found to increase the protein's Ca(2)(+)-binding affinity. One explanation for this effect was that peptide binding introduced a structural change that increased the number of Ca(2+) ligands and/or improved the Ca(2+) coordination geometry of S100B. This possibility was ruled out when the structures of S100B-Ca(2+)-TRTK-12 and S100B-Ca(2+) were compared and calcium ion coordination by the protein was found to be nearly identical in both EF-hand calcium-binding domains (RMSD=0.19). On the other hand, B-factors for residues in EF2 of Ca(2+)-S100B were found to be significantly lowered with TRTK-12 bound. This result is consistent with NMR (15)N relaxation studies that showed that TRTK-12 binding eliminated dynamic properties observed in Ca(2+)-S100B. Such a loss of protein motion may also provide an explanation for how calcium-ion-binding affinity is increased upon binding a target. Lastly, it follows that any small-molecule inhibitor bound to Ca(2+)-S100B would also have to cause an increase in calcium-ion-binding affinity to be effective therapeutically inside a cell, so these data need to be considered in future drug design studies involving S100B.
Rosario Donato - One of the best experts on this subject based on the ideXlab platform.
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Levels of S100B protein drive the reparative process in acute muscle injury and muscular dystrophy
Scientific reports, 2017Co-Authors: Francesca Riuzzi, Guglielmo Sorci, Ileana Giambanco, Sara Beccafico, Roberta Sagheddu, Sara Chiappalupi, Oxana Bereshchenko, Carlo Riccardi, Rosario DonatoAbstract:Regeneration of injured skeletal muscles relies on a tightly controlled chain of cellular and molecular events. We show that appropriate levels of S100B protein are required for timely muscle regeneration after acute injury. S100B released from damaged myofibers and infiltrating macrophages expands the myoblast population, attracts macrophages and promotes their polarization into M2 (pro-regenerative) phenotype, and modulates collagen deposition, by interacting with RAGE (receptor for advanced glycation end-products) or FGFR1 (fibroblast growth factor receptor 1) depending on the muscle repair phase and local conditions. However, persistence of high S100B levels compromises the regeneration process prolonging myoblast proliferation and macrophage infiltration, delaying M1/M2 macrophage transition, and promoting deposition of fibrotic tissue via RAGE engagement. Interestingly, S100B is released in high abundance from degenerating muscles of mdx mice, an animal model of Duchenne muscular dystrophy (DMD), and blocking S100B ameliorates histopathology. Thus, levels of S100B differentially affect skeletal muscle repair upon acute injury and in the context of muscular dystrophy, and S100B might be regarded as a potential molecular target in DMD.
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S100B protein regulates myoblast proliferation and differentiation by activating fgfr1 in a bfgf dependent manner
Journal of Cell Science, 2011Co-Authors: Francesca Riuzzi, Guglielmo Sorci, Rosario DonatoAbstract:S100B protein has been shown to exert anti-myogenic and mitogenic effects in myoblast cultures through inhibition of the myogenic p38 MAPK and activation of the mitogenic ERK1/2. However, the receptor mediating these effects had not been identified. Here, we show that S100B increases and/or stabilizes the binding of basic fibroblast growth factor (bFGF) to bFGF receptor 1 (FGFR1) by interacting with bFGF, thereby enhancing FGFR1 activation and the mitogenic and anti-myogenic effects of FGFR1. S100B also binds to its canonical receptor RAGE (receptor for advanced glycation end-products), a multi-ligand receptor previously shown to transduce a pro-myogenic signal when activated by HMGB1, and recruits RAGE into a RAGE-S100B-bFGF-FGFR1 complex. However, when bound to S100B-bFGF-FGFR1, RAGE can no longer stimulate myogenic differentiation, whereas in the absence of either bFGF or FGFR1, binding of S100B to RAGE results in stimulation of RAGE anti-mitogenic and promyogenic signaling. An S100B-bFGF-FGFR1 complex also forms in Rage(-/-) myoblasts, leading to enhanced proliferation and reduced differentiation, which points to a dispensability of RAGE for the inhibitory effects of S100B on myoblasts under the present experimental conditions. These results reveal a new S100B-interacting protein - bFGF - in the extracellular milieu and suggest that S100B stimulates myoblast proliferation and inhibits myogenic differentiation by activating FGFR1 in a bFGF-dependent manner.
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S100B protein stimulates microglia migration via rage dependent up regulation of chemokine expression and release
Journal of Biological Chemistry, 2011Co-Authors: Roberta Bianchi, Ileana Giambanco, Eirini Kastrisianaki, Rosario DonatoAbstract:The Ca2+-binding protein of the EF-hand type, S100B, is abundantly expressed in and secreted by astrocytes, and release of S100B from damaged astrocytes occurs during the course of acute and chronic brain disorders. Thus, the concept has emerged that S100B might act an unconventional cytokine or a damage-associated molecular pattern protein playing a role in the pathophysiology of neurodegenerative disorders and inflammatory brain diseases. S100B proinflammatory effects require relatively high concentrations of the protein, whereas at physiological concentrations S100B exerts trophic effects on neurons. Most if not all of the extracellular (trophic and toxic) effects of S100B in the brain are mediated by the engagement of RAGE (receptor for advanced glycation end products). We show here that high S100B stimulates murine microglia migration in Boyden chambers via RAGE-dependent activation of Src kinase, Ras, PI3K, MEK/ERK1/2, RhoA/ROCK, Rac1/JNK/AP-1, Rac1/NF-κB, and, to a lesser extent, p38 MAPK. Recruitment of the adaptor protein, diaphanous-1, a member of the formin protein family, is also required for S100B/RAGE-induced migration of microglia. The S100B/RAGE-dependent activation of diaphanous-1/Rac1/JNK/AP-1, Ras/Rac1/NF-κB and Src/Ras/PI3K/RhoA/diaphanous-1 results in the up-regulation of expression of the chemokines, CCL3, CCL5, and CXCL12, whose release and activity are required for S100B to stimulate microglia migration. Lastly, RAGE engagement by S100B in microglia results in up-regulation of the chemokine receptors, CCR1 and CCR5. These results suggests that S100B might participate in the pathophysiology of brain inflammatory disorders via RAGE-dependent regulation of several inflammation-related events including activation and migration of microglia.
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S100B protein in the nervous system and cardiovascular apparatus in normal and pathological conditions
Cardiovascular Psychiatry and Neurology, 2010Co-Authors: Rosario Donato, Claus W HeizmannAbstract:Accumulating evidence suggests that S100B, a Ca2+-binding protein of the EF-hand type, functions as a regulator of intracellular activities and as an extracellular signal. Within cells, S100B interacts with a relatively large number of target proteins thereby regulating their functions (Figure 1). While most of these interactions are Ca2+ dependent, in some instances S100B/target protein interactions are not. S100B is also secreted by certain cell types and released by activated/damaged/necrotic cells. Secreted/released S100B can affect cellular functions with varying effects depending on its local concentration. Figure 1 Schematic representation of intracellular regulatory effects of S100B. S100B is not a ubiquitous protein, its expression being restricted to astrocytes, Schwann cells, ependymocytes, certain neuronal populations, adipocytes, chondrocytes, melanocytes, dendritic cells, muscle satellite cells, skeletal myofibers, arterial smooth muscle cells, and bronchial epithelium, in normal physiological conditions. However, the S100B cell expression pattern during prenatal and postnatal development might be different (there is limited information about this issue); S100B expression levels in certain cell types may be varied in response to extracellular factors; levels of S100B are high in several cancer cells; S100B expression may be induced in cardiomyocytes and arterial endothelium in response to norepinephrine. Serum levels of S100B in normal prepubescent and postpubescent human subjects are relatively high and low, respectively, and increases in S100B serum levels are found in physiological conditions (such as intense physical exercise) and in several pathological conditions (mostly, brain diseases, certain psychiatric disorders, melanoma, and heart infarction and insufficiency). The present special issue of “Cardiovascular Psychiatry and Neurology” focuses on the brain-heart role of S100B. In the adult brain, S100B amounts to ~0.5% of cytoplasmic protein content and is most abundant in astrocytes (with an estimated concentration of ~10 μM), where the protein is found diffusely in the cytoplasm and associated with microtubules, GFAP intermediate filaments, and intracellular membranes. Such a high concentration and its diffuse localization in the cytoplasm explain S100B's ability to interact with enzymes, enzyme substrates, scaffold/adaptor proteins, transcription factors, and cytoskeleton constituents thereby regulating energy metabolism, Ca2+ homeostasis, transcription, and cell shape, proliferation, differentiation, and motility (Figure 1). Besides, ~5% of S100B is being constitutively secreted by astrocytes; S100B secretion can be enhanced or reduced by a number of factors and/or conditions; in case of brain damage, large amounts of S100B are being passively released, with a fraction of the protein diffusing into the cerebrospinal fluid (CSF) and blood. Whereas increases in the CFS and/or serum S100B content are taken as an indication of brain damage (yet increases in serum S100B content might point to nonbrain damage as well), a large body of evidence indicates that brain extracellular S100B behaves as a neurotrophin in normal physiological conditions and as a damage-associated molecular pattern (DAMP) factor upon massive release consequent to astrocyte activation or necrosis. In this latter case, S100B participates in the amplification of the brain inflammatory response by activating microglia and astrocytes and exerting toxic effects on neurons. RAGE (receptor for advanced glycation end products) has been identified as the receptor transducing both trophic and toxic effects of S100B in the brain and might act as a coreceptor supporting certain S100B effects on microglia (Figure 2). Figure 2 Schematic representation of extracellular regulatory effects of S100B on neurons, microglia, and astrocytes. As an intracellular regulator, S100B also participates in myocardium remodeling post infarction inhibiting the hypertrophic response in cardiomyocytes surviving the insult, and once released from necrotic cardiomyocytes, it acts as a DAMP factor causing cell death again via RAGE engagement. Adipocytes also release S100B in response to catecholamines with unidentified effects, though. Lastly, as a DAMP factor, S100B also participates in the pathophysiology of atherosclerosis stimulating vascular smooth cell proliferation and activating monocytes/macrophages. The present issue of “Cardiovascular Psychiatry and Neurology” attempts to delineate the functional roles of S100B in the brain and the cardiovascular apparatus and to update the information about this multifaceted protein. We are confident that both cell biologists and clinicians will benefit by the reading of the papers presented therein. Rosario Donato Claus W. Heizmann
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S100B protein a damage associated molecular pattern protein in the brain and heart and beyond
Cardiovascular Psychiatry and Neurology, 2010Co-Authors: Guglielmo Sorci, Francesca Riuzzi, Roberta Bianchi, Claudia Tubaro, Cataldo Arcuri, Ileana Giambanco, Rosario DonatoAbstract:S100B belongs to a multigenic family of Ca2+-binding proteins of the EF-hand type and is expressed in high abundance in the brain. S100B interacts with target proteins within cells thereby altering their functions once secreted/released with the multiligand receptor RAGE. As an intracellular regulator, S100B affects protein phosphorylation, energy metabolism, the dynamics of cytoskeleton constituents (and hence, of cell shape and migration), Ca2+ homeostasis, and cell proliferation and differentiation. As an extracellular signal, at low, physiological concentrations, S100B protects neurons against apoptosis, stimulates neurite outgrowth and astrocyte proliferation, and negatively regulates astrocytic and microglial responses to neurotoxic agents, while at high doses S100B causes neuronal death and exhibits properties of a damage-associated molecular pattern protein. S100B also exerts effects outside the brain; as an intracellular regulator, S100B inhibits the postinfarction hypertrophic response in cardiomyocytes, while as an extracellular signal, (high) S100B causes cardiomyocyte death, activates endothelial cells, and stimulates vascular smooth muscle cell proliferation.
Nicole Assard - One of the best experts on this subject based on the ideXlab platform.
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S100B expression defines a state in which GFAP-expressing cells lose their neural stem cell potential and acquire a more mature developmental stage.
Glia, 2007Co-Authors: Eric Raponi, Jacques Baudier, Nicole Assard, Christian Delphin, Fabien Agenes, Catherine Legraverend, Jean-christophe DeloulmeAbstract:During the postnatal development, astrocytic cells in the neocortex progressively lose their neural stem cell (NSC) potential, whereas this peculiar attribute is preserved in the adult subventricular zone (SVZ). To understand this fundamental difference, many reports suggest that adult subventricular GFAP-expressing cells might be maintained in immature developmental stage. Here, we show that S100B, a marker of glial cells, is absent from GFAP-expressing cells of the SVZ and that its onset of expression characterizes a terminal maturation stage of cortical astrocytic cells. Nevertheless, when cultured in vitro, SVZ astrocytic cells developed as S100B expressing cells, as do cortical astrocytic cells, suggesting that SVZ microenvironment represses S100B expression. Using transgenic S100B-EGFP cells, we then demonstrated that S100B expression coincides with the loss of neurosphere forming abilities of GFAP expressing cells. By doing grafting experiments with cells derived from beta-actin-GFP mice, we next found that S100B expression in astrocytic cells is repressed in the SVZ, but not in the striatal parenchyma. Furthermore, we showed that treatment with epidermal growth factor represses S100B expression in GFAP-expressing cells in vitro as well as in vivo. Altogether, our results indicate that the S100B expression defines a late developmental stage after which GFAP-expressing cells lose their NSC potential and suggest that S100B expression is repressed by adult SVZ microenvironment.
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S100B expression defines a state in which gfap expressing cells lose their neural stem cell potential and acquire a more mature developmental stage
Glia, 2007Co-Authors: Eric Raponi, Nicole Assard, Christian Delphin, Fabien AgenesAbstract:During the post-natal development, GFAP-expressing cells in the parenchyma progressively lose their neural stem cell (NSC) potential, whereas this peculiar attribute is preserved in GFAP-expressing cells of adult germinal zones. Although the relationship between astrocytes localized in the parenchyma and those in the germinal zones is elusive, many reports suggest that GFAP-expressing cells contained in germinal zones are maintained in immature developmental stage. Starting from the observation that the pan-astrocytic marker S100B is not expressed in the GFAP-expressing cells of adult germinal zones, we first investigated the relationship between S100B expression and the developmental status of these astrocytic cells. We demonstrated that long after the loss of RC2 and gain of GFAP, the onset of S100B expression characterizes a mature developmental stage in mouse telencephalic GFAP-expressing cells, both in vitro and in vivo. Using a transgenic S100B-EGFP mouse-derived culture model, we next demonstrate that in vitro, S100B expression in GFAP-expressing cells coincides with the loss of their NSC potential. Through a series of ectopic and orthotopic grafting experiments, we found that in the adult subventricular zone, S100B expression is controlled by environmental cues. Furthermore, we showed that treatment with epidermal growth factor represses S100B expression in GFAP-expressing cells in vitro as well as in mouse forebrain. Altogether, our results indicate that the S100B expression defines a late developmental stage after which GFAP-expressing cells lose their NSC potential.
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s100a6 and s100a11 are specific targets of the calcium and zinc binding S100B protein in vivo
Journal of Biological Chemistry, 2000Co-Authors: Jean-christophe Deloulme, Nicole Assard, Gaelh Ouengue Mbele, Carole Mangin, Ryozo Kuwano, Jacques BaudierAbstract:In solution, S100B protein is a noncovalent homodimer composed of two subunits associated in an antiparallel manner. Upon calcium binding, the conformation of S100B changes dramatically, leading to the exposure of hydrophobic residues at the surface of S100B. The residues in the C-terminal domain of S100B encompassing Phe87 and Phe88 have been implicated in interaction with target proteins. In this study, we used two-hybrid technology to identify specific S100B target proteins. Using S100B as bait, we identify S100A6 and S100A11 as specific targets for S100B. S100A1, the closest homologue of S100B, is capable of interaction with S100B but does not interact with S100A6 or S100A11. S100B, S100A6, and S100A11 isoforms are co-regulated and co-localized in astrocytoma U373 cells. Furthermore, co-immunoprecipitation experiments demonstrated that Ca2+/Zn2+stabilizes S100B-S100A6 and S100B-S100A11 heterocomplexes. Deletion of the C-terminal domain or mutation of Phe87 and Phe88 residues has no effect on S100B homodimerization and heterodimerization with S100A1 but drastically decreases interaction between S100B and S100A6 or S100A11. Our data suggest that the interaction between S100B and S100A6 or S100A11 should not be viewed as a typical S100 heterodimerization but rather as a model of interaction between S100B and target proteins.
Jacques Baudier - One of the best experts on this subject based on the ideXlab platform.
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S100B expression defines a state in which GFAP-expressing cells lose their neural stem cell potential and acquire a more mature developmental stage.
Glia, 2007Co-Authors: Eric Raponi, Jacques Baudier, Nicole Assard, Christian Delphin, Fabien Agenes, Catherine Legraverend, Jean-christophe DeloulmeAbstract:During the postnatal development, astrocytic cells in the neocortex progressively lose their neural stem cell (NSC) potential, whereas this peculiar attribute is preserved in the adult subventricular zone (SVZ). To understand this fundamental difference, many reports suggest that adult subventricular GFAP-expressing cells might be maintained in immature developmental stage. Here, we show that S100B, a marker of glial cells, is absent from GFAP-expressing cells of the SVZ and that its onset of expression characterizes a terminal maturation stage of cortical astrocytic cells. Nevertheless, when cultured in vitro, SVZ astrocytic cells developed as S100B expressing cells, as do cortical astrocytic cells, suggesting that SVZ microenvironment represses S100B expression. Using transgenic S100B-EGFP cells, we then demonstrated that S100B expression coincides with the loss of neurosphere forming abilities of GFAP expressing cells. By doing grafting experiments with cells derived from beta-actin-GFP mice, we next found that S100B expression in astrocytic cells is repressed in the SVZ, but not in the striatal parenchyma. Furthermore, we showed that treatment with epidermal growth factor represses S100B expression in GFAP-expressing cells in vitro as well as in vivo. Altogether, our results indicate that the S100B expression defines a late developmental stage after which GFAP-expressing cells lose their NSC potential and suggest that S100B expression is repressed by adult SVZ microenvironment.
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nuclear expression of S100B in oligodendrocyte progenitor cells correlates with differentiation toward the oligodendroglial lineage and modulates oligodendrocytes maturation
Molecular and Cellular Neuroscience, 2004Co-Authors: Eric Raponi, Alexander Marks, Benoit J Gentil, Nathalie Bertacchi, G Labourdette, Jacques BaudierAbstract:The S100B protein belongs to the S100 family of EF-hand calcium binding proteins implicated in cell growth and differentiation. Here, we show that in the developing and the adult mouse brain, S100B is expressed in oligodendroglial progenitor cells (OPC) committed to differentiate into the oligodendrocyte (OL) lineage. Nuclear S100B accumulation in OPC correlates with the transition from the fast dividing multipotent stage to the morphological differentiated, slow proliferating, pro-OL differentiation stage. In the adult, S100B expression is down-regulated in mature OLs that have established contacts with their axonal targets, suggesting a nuclear S100B function during oligodendroglial cells maturation. In vitro, the morphological transformation and maturation of pro-OL cells are delayed in the absence of S100B. Moreover, mice lacking S100B show an apparent delay in OPC maturation in response to demyelinating insult. We propose that nuclear S100B participates in the regulation of oligodendroglial cell maturation.
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the giant protein ahnak is a specific target for the calcium and zinc binding S100B protein potential implications for ca2 homeostasis regulation by S100B
Journal of Biological Chemistry, 2001Co-Authors: Benoit J Gentil, Gaelh Ouengue Mbele, Christian Delphin, Myriam Ferro, Jerome Garin, Jacques BaudierAbstract:Abstract Transformation of rat embryo fibroblast clone 6 cells by ras and temperature-sensitive p53val135 is reverted by ectopic expression of the calcium- and zinc-binding protein S100B. In an attempt to define the molecular basis of the S100B action, we have identified the giant phosphoprotein AHNAK as the major and most specific Ca2+-dependent S100B target protein in rat embryo fibroblast cells. We next characterized AHNAK as a major Ca2+-dependent S100B target protein in the rat glial C6 and human U-87MG astrocytoma cell lines. AHNAK binds to S100B-Sepharose beads and is also recovered in anti-S100B immunoprecipitates in a strict Ca2+- and Zn2+-dependent manner. Using truncated AHNAK fragments, we demonstrated that the domains of AHNAK responsible for interaction with S100B correspond to repeated motifs that characterize the AHNAK molecule. These motifs show no binding to calmodulin or to S100A6 and S100A11. We also provide evidence that the binding of 2 Zn2+ equivalents/mol S100B enhances Ca2+-dependent S100B-AHNAK interaction and that the effect of Zn2+ relies on Zn2+-dependent regulation of S100B affinity for Ca2+. Taking into consideration that AHNAK is a protein implicated in calcium flux regulation, we propose that the S100B-AHNAK interaction may participate in the S100B-mediated regulation of cellular Ca2+ homeostasis.
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s100a6 and s100a11 are specific targets of the calcium and zinc binding S100B protein in vivo
Journal of Biological Chemistry, 2000Co-Authors: Jean-christophe Deloulme, Nicole Assard, Gaelh Ouengue Mbele, Carole Mangin, Ryozo Kuwano, Jacques BaudierAbstract:In solution, S100B protein is a noncovalent homodimer composed of two subunits associated in an antiparallel manner. Upon calcium binding, the conformation of S100B changes dramatically, leading to the exposure of hydrophobic residues at the surface of S100B. The residues in the C-terminal domain of S100B encompassing Phe87 and Phe88 have been implicated in interaction with target proteins. In this study, we used two-hybrid technology to identify specific S100B target proteins. Using S100B as bait, we identify S100A6 and S100A11 as specific targets for S100B. S100A1, the closest homologue of S100B, is capable of interaction with S100B but does not interact with S100A6 or S100A11. S100B, S100A6, and S100A11 isoforms are co-regulated and co-localized in astrocytoma U373 cells. Furthermore, co-immunoprecipitation experiments demonstrated that Ca2+/Zn2+stabilizes S100B-S100A6 and S100B-S100A11 heterocomplexes. Deletion of the C-terminal domain or mutation of Phe87 and Phe88 residues has no effect on S100B homodimerization and heterodimerization with S100A1 but drastically decreases interaction between S100B and S100A6 or S100A11. Our data suggest that the interaction between S100B and S100A6 or S100A11 should not be viewed as a typical S100 heterodimerization but rather as a model of interaction between S100B and target proteins.
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cysteine oxidation in the mitogenic S100B protein leads to changes in phosphorylation by catalytic ckii α subunit
Journal of Biological Chemistry, 1998Co-Authors: Christian Scotto, Jerome Garin, Yves Mely, Hiroshi Ohshima, Claude Cochet, E M Chambaz, Jacques BaudierAbstract:Abstract The glial-derived calcium-binding protein S100B can be secreted to act as a neurotrophic factor or a mitogen, stimulating proliferation of glial cells. The extracellular S100B activities rely on the oxidation of the protein cysteine residues (Kligman, D., and Marshak, D. R. (1985) Proc. Natl. Acad. Sci. U. S. A. 82, 7136–7139; Winningham-Major, F., Staecker, J. L., Barger, S. W., Coats, S., and Van Eldik, L. J. (1989) J. Cell Biol. 109, 3063–3071). Here we show that oxidation of the S100B cysteine residues, Cys-68 and Cys-84, induces a conformational change in the protein structure, unmasking a canonical CKII phosphorylation site located within the typical EF-hand calcium-binding site IIβ. Intrasubunit disulfide-bridged S100B monomer and disulfide-bonded S100B dimer are phosphorylated by the catalytic CKII-α subunit on Ser-62 with a K m of 0.5 μm and a V max of 10 pmol/min/100 pmol of S100B. Oxidized S100B is the best in vitro CKII-α substrate identified so far. Next we show that intrasubunit disulfide-bridged S100B monomer is the most potent S100B species to stimulate [3H]thymidine uptake by C6 glial cells in culture. In addition, the phosphorylated intrasubunit disulfide-bridged S100B monomer retains apparent mitogenic activity toward C6 glial cells, and hence, 32P-labeled S100B should be a useful probe for characterizing the mechanisms by which extracellular oxidized S100B functions. Finally, we show that formation of intrasubunit disulfide-bridged S100B monomer is stimulated by peroxynitrite anion, suggesting that production of mitogenic S100B species could be enhanced in neuropathology associated with peroxynitrite anion production.
Paul T. Wilder - One of the best experts on this subject based on the ideXlab platform.
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Model for S100B-dependent inhibition of IL6/STAT3 signaling and its possible role in the pathology of malignant melanoma.
'Public Library of Science (PLoS)', 2021Co-Authors: Milad J Alasady, Paul T. Wilder, David J. Weber, Adam D Pierce, Michael C Cavalier, Alexander R. Terry, Catherine S. Blaha, Kaylin A. Adipietro, Nissim HayAbstract:(A) Elevated levels of S100B found in most melanoma binds RSK in a calcium-dependent manner and sterically prevents its ERK-dependent phosphorylation at T573, which is needed for RSK nuclear localization (8). As a result, it is proposed here that elevated S100B inhibits expression and secretion of IL6 and phosphorylation and transcriptional activity of STAT3 (Figs 1–4). S100B-dependent inhibition of IL6 and STAT3 phosphorylation is via RSK (Fig 5). S100B also inhibits phosphorylation of CREB in the nucleus. Given that S100B forms a complex with RSK and prevents RSK nuclear localization, it is proposed that S100B inhibits phosphorylation of CREB in the nucleus via RSK (Fig 6). Thus, CREB-dependent expression of IL6 is inhibited, as is IL6/STAT3 signaling. (B) During early stages of melanoma progression, it is hypothesized that IL6 induces anti-proliferative mechanism to inhibit the progression of melanoma. Thus, when S100B levels elevate to a critical threshold in a pre-metastatic state, it blocks IL6 expression and initiates the transition of melanoma from pre-malignant to a malignant form.
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novel protein inhibitor interactions in site 3 of ca 2 bound S100B as discovered by x ray crystallography
Acta Crystallographica Section D-biological Crystallography, 2016Co-Authors: Michael C Cavalier, Paul T. Wilder, Adam D Pierce, Alexander D. Mackerell, Zephan Melville, E Aligholizadeh, E P Raman, Lei Fang, Milad J Alasady, David J. WeberAbstract:Structure-based drug discovery is under way to identify and develop small-molecule S100B inhibitors (SBiXs). Such inhibitors have therapeutic potential for treating malignant melanoma, since high levels of S100B downregulate wild-type p53 tumor suppressor function in this cancer. Computational and X-ray crystallographic studies of two S100B-SBiX complexes are described, and both compounds (apomorphine hydrochloride and ethidium bromide) occupy an area of the S100B hydrophobic cleft which is termed site 3. These data also reveal novel protein-inhibitor interactions which can be used in future drug-design studies to improve SBiX affinity and specificity. Of particular interest, apomorphine hydrochloride showed S100B-dependent killing in melanoma cell assays, although the efficacy exceeds its affinity for S100B and implicates possible off-target contributions. Because there are no structural data available for compounds occupying site 3 alone, these studies contribute towards the structure-based approach to targeting S100B by including interactions with residues in site 3 of S100B.
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The calcium-binding protein S100B down-regulates p53 and apoptosis in malignant melanoma.
The Journal of biological chemistry, 2010Co-Authors: Jing Lin, Paul T. Wilder, Qingyuan Yang, David J. WeberAbstract:The S100B-p53 protein complex was discovered in C8146A malignant melanoma, but the consequences of this interaction required further study. When S100B expression was inhibited in C8146As by siRNA (siRNA(S100B)), wt p53 mRNA levels were unchanged, but p53 protein, phosphorylated p53, and p53 gene products (i.e. p21 and PIDD) were increased. siRNA(S100B) transfections also restored p53-dependent apoptosis in C8146As as judged by poly(ADP-ribose) polymerase cleavage, DNA ladder formation, caspase 3 and 8 activation, and aggregation of the Fas death receptor (+UV); whereas, siRNA(S100B) had no effect in SK-MEL-28 cells containing elevated S100B and inactive p53 (p53R145L mutant). siRNA(S100B)-mediated apoptosis was independent of the mitochondria, because no changes were observed in mitochondrial membrane potential, cytochrome c release, caspase 9 activation, or ratios of pro- and anti-apoptotic proteins (BAX, Bcl-2, and Bcl-X(L)). As expected, cells lacking S100B (LOX-IM VI) were not affected by siRNA(S100B), and introduction of S100B reduced their UV-induced apoptosis activity by 7-fold, further demonstrating that S100B inhibits apoptosis activities in p53-containing cells. In other wild-type p53 cells (i.e. C8146A, UACC-2571, and UACC-62), S100B was found to contribute to cell survival after UV treatment, and for C8146As, the decrease in survival after siRNA(S100B) transfection (+UV) could be reversed by the p53 inhibitor, pifithrin-alpha. In summary, reducing S100B expression with siRNA was sufficient to activate p53, its transcriptional activation activities, and p53-dependent apoptosis pathway(s) in melanoma involving the Fas death receptor and perhaps PIDD. Thus, a well known marker for malignant melanoma, S100B, likely contributes to cancer progression by down-regulating the tumor suppressor protein, p53.
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the effects of capz peptide trtk 12 binding to S100B ca2 as examined by nmr and x ray crystallography
Journal of Molecular Biology, 2010Co-Authors: Thomas H. Charpentier, Paul T. Wilder, Melissa A. Liriano, Kristen M. Varney, Eric A. Toth, Laura E Thompson, Edwin Pozharski, David J. WeberAbstract:Structure-based drug design is underway to inhibit the S100B-p53 interaction as a strategy for treating malignant melanoma. X-ray crystallography was used here to characterize an interaction between Ca(2)(+)-S100B and TRTK-12, a target that binds to the p53-binding site on S100B. The structures of Ca(2+)-S100B (1.5-A resolution) and S100B-Ca(2)(+)-TRTK-12 (2.0-A resolution) determined here indicate that the S100B-Ca(2+)-TRTK-12 complex is dominated by an interaction between Trp7 of TRTK-12 and a hydrophobic binding pocket exposed on Ca(2+)-S100B involving residues in helices 2 and 3 and loop 2. As with an S100B-Ca(2)(+)-p53 peptide complex, TRTK-12 binding to Ca(2+)-S100B was found to increase the protein's Ca(2)(+)-binding affinity. One explanation for this effect was that peptide binding introduced a structural change that increased the number of Ca(2+) ligands and/or improved the Ca(2+) coordination geometry of S100B. This possibility was ruled out when the structures of S100B-Ca(2+)-TRTK-12 and S100B-Ca(2+) were compared and calcium ion coordination by the protein was found to be nearly identical in both EF-hand calcium-binding domains (RMSD=0.19). On the other hand, B-factors for residues in EF2 of Ca(2+)-S100B were found to be significantly lowered with TRTK-12 bound. This result is consistent with NMR (15)N relaxation studies that showed that TRTK-12 binding eliminated dynamic properties observed in Ca(2+)-S100B. Such a loss of protein motion may also provide an explanation for how calcium-ion-binding affinity is increased upon binding a target. Lastly, it follows that any small-molecule inhibitor bound to Ca(2+)-S100B would also have to cause an increase in calcium-ion-binding affinity to be effective therapeutically inside a cell, so these data need to be considered in future drug design studies involving S100B.
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divalent metal ion complexes of S100B in the absence and presence of pentamidine
Journal of Molecular Biology, 2008Co-Authors: Thomas H. Charpentier, Paul T. Wilder, Melissa A. Liriano, Kristen M. Varney, Andrew Coop, Alexander D. Mackerell, Eric A. Toth, Edwin Pozharski, David J. WeberAbstract:As part of an effort to inhibit S100B, structures of pentamidine (Pnt) bound to Ca{sup 2+}-loaded and Zn{sup 2+},Ca{sup 2+}-loaded S100B were determined by X-ray crystallography at 2.15 {angstrom} (R{sub free} = 0.266) and 1.85 {angstrom} (R{sub free} = 0.243) resolution, respectively. These data were compared to X-ray structures solved in the absence of Pnt, including Ca{sup 2+}-loaded S100B and Zn{sup 2+},Ca{sup 2+}-loaded S100B determined here (1.88 {angstrom}; R{sub free} = 0.267). In the presence and absence of Zn{sup 2+}, electron density corresponding to two Pnt molecules per S100B subunit was mapped for both drug-bound structures. One Pnt binding site (site 1) was adjacent to a p53 peptide binding site on S100B ({+-} Zn{sup 2+}), and the second Pnt molecule was mapped to the dimer interface (site 2; {+-} Zn{sup 2+}) and in a pocket near residues that define the Zn{sup 2+} binding site on S100B. In addition, a conformational change in S100B was observed upon the addition of Zn{sup 2+} to Ca{sup 2+}-S100B, which changed the conformation and orientation of Pnt bound to sites 1 and 2 of Pnt-Zn{sup 2+},Ca{sup 2+}-S100B when compared to Pnt-Ca{sup 2+}-S100B. That Pnt can adapt to this Zn{sup 2+}-dependent conformational change was unexpected andmore » provides a new mode for S100B inhibition by this drug. These data will be useful for developing novel inhibitors of both Ca{sup 2+}- and Ca{sup 2+},Zn{sup 2+}-bound S100B.« less
