S100B increases proliferation in PC12 neuronal cells and reduces their responsiveness to nerve growth factor via Akt activation

S100B actions on glial and neuronal cells in the developing brain: an overview

The S100B is a member of the S100 family of "E" helix-loop- "F" helix structure (EF) hand calcium-binding proteins expressed in diverse glial, selected neuronal, and various peripheral cells, exerting differential effects. In particular, this review compiles descriptions of the detection of S100B in different brain cells localized in specific regions during the development of humans, mice, and rats. Then, it summarizes S100B's actions on the differentiation, growth, and maturation of glial and neuronal cells in humans and rodents. Particular emphasis is placed on S100B regulation of the differentiation and maturation of astrocytes, oligodendrocytes (OL), and the stimulation of dendritic development in serotoninergic and cerebellar neurons during embryogenesis. We also summarized reports that associate morphological alterations (impaired neurite outgrowth, neuronal migration, altered radial glial cell morphology) of specific neural cell groups during neurodevelopment and functional disturbances (slower rate of weight gain, impaired spatial learning) with changes in the expression of S100B caused by different conditions and stimuli as exposure to stress, ethanol, cocaine and congenital conditions such as Down's Syndrome. Taken together, this evidence highlights the impact of the expression and early actions of S100B in astrocytes, OL, and neurons during brain development, which is reflected in the alterations in differentiation, growth, and maturation of these cells. This allows the integration of a spatiotemporal panorama of S100B actions in glial and neuronal cells in the developing brain.

The Role of Glycogen Synthase Kinase-3β in the Zinc-Mediated Neuroprotective Effect of Metformin in Rats with Glutamate Neurotoxicity

Metformin has been suggested to have protective effects on the central nervous system, but the mechanism is unknown. The similarity between the effects of metformin and the inhibition of glycogen synthase kinase (GSK)-3β suggests that metformin may inhibit GSK-3β. In addition, zinc is an important element that inhibits GSK-3β by phosphorylation. In this study, we investigated whether the effects of metformin on neuroprotection and neuronal survival were mediated by zinc-dependent inhibition of GSK-3β in rats with glutamate-induced neurotoxicity. Forty adult male rats were divided into 5 groups: control, glutamate, metformin + glutamate, zinc deficiency + glutamate, and zinc deficiency + metformin + glutamate. Zinc deficiency was induced with a zinc-poor pellet. Metformin was orally administered for 35 days. D-glutamic acid was intraperitoneally administered on the 35th day. On the 38th day, neurodegeneration was examined histopathologically, and the effects on neuronal protection and survival were evaluated via intracellular S-100β immunohistochemical staining. The findings were examined in relation to nonphosphorylated (active) GSK-3β levels and oxidative stress parameters in brain tissue and blood. Neurodegeneration was increased (p < 0.05) in rats fed a zinc-deficient diet. Active GSK-3β levels were increased in groups with neurodegeneration (p < 0.01). Decreased neurodegeneration, increased neuronal survival (p < 0.01), decreased active GSK-3β (p < 0.01) levels and oxidative stress parameters, and increased antioxidant parameters were observed in groups treated with metformin (p < 0.01). Metformin had fewer protective effects on rats fed a zinc-deficient diet. Metformin may exert neuroprotective effects and increase S-100β-mediated neuronal survival by zinc-dependent inhibition of GSK-3β during glutamate neurotoxicity.

Biochemical and Anthropometric Parameters for the Early Recognition of the Intrauterine Growth Restriction and Preterm Neonates at Risk of Impaired Neurodevelopment

BACKGROUND

S100B and Tau are implicated with both brain growth and injury. Their urinary levels in 30-to-40-day-old full-term, preterm, IUGR, and preterm-IUGR subjects were measured to investigate their possible relationship with future delayed neurodevelopment.

METHODS

Values were related to the neuro-behavioral outcome at two years of age, as well as to brain volumes and urinary NGF assessed at the same postnatal time point.

RESULTS

Using the Griffiths III test, cognitive and motor performances were determined to establish subgroups characterized by either normal or impaired neuro-behavior. The latter included preterm, IUGR, and preterm-IUGR individuals who exhibited significantly higher and lower S100B and Tau levels, respectively, along with markedly reduced cerebral volumes and urinary NGF, as previously demonstrated. Contrary to NGF, however, Tau and S100B displayed a weak correlation with brain volumes.

CONCLUSIONS

Delayed cognitive and motor performances observed in two-year-old preterm and IUGR-born individuals were also found to be associated with anomalous urinary levels of S100B and Tau, assessed at 30-40 days of the postnatal period, and their changes did not correlate with brain growth. Thus, our data suggests that, in addition to cerebral volumes and NGF, urinary S100B and Tau can also be considered as valuable parameters for the early detection of future neurodevelopmental abnormalities.

Ultra High-plex Spatial Proteogenomic Investigation of Giant Cell Glioblastoma Multiforme Immune Infiltrates Reveals Distinct Protein and RNA Expression Profiles

A deeper understanding of complex biological processes, including tumor development and immune response, requires ultra high-plex, spatial interrogation of multiple "omes". Here we present the development and implementation of a novel spatial proteogenomic (SPG) assay on the GeoMx Digital Spatial Profiler platform with next-generation sequencing readout that enables ultra high-plex digital quantitation of proteins (>100-plex) and RNA (whole transcriptome, >18,000-plex) from a single formalin-fixed paraffin-embedded (FFPE) sample. This study highlighted the high concordance, R > 0.85 and <15% change in sensitivity between the SPG assay and the single-analyte assays on various cell lines and tissues from human and mouse. Furthermore, we demonstrate that the SPG assay was reproducible across multiple users. When used in conjunction with advanced cellular neighborhood segmentation, distinct immune or tumor RNA and protein targets were spatially resolved within individual cell subpopulations in human colorectal cancer and non-small cell lung cancer. We used the SPG assay to interrogate 23 different glioblastoma multiforme (GBM) samples across four pathologies. The study revealed distinct clustering of both RNA and protein based on pathology and anatomic location. The in-depth investigation of giant cell glioblastoma multiforme (gcGBM) revealed distinct protein and RNA expression profiles compared with that of the more common GBM. More importantly, the use of spatial proteogenomics allowed simultaneous interrogation of critical protein posttranslational modifications alongside whole transcriptomic profiles within the same distinct cellular neighborhoods.

Significance

We describe ultra high-plex spatial proteogenomics; profiling whole transcriptome and high-plex proteomics on a single FFPE tissue section with spatial resolution. Investigation of gcGBM versus GBM revealed distinct protein and RNA expression profiles.

Blood-Brain Barrier-Associated Proteins Are Elevated in Serum of Epilepsy Patients

Blood-brain barrier (BBB) dysfunction emerges as one of the mechanisms underlying the induction of seizures and epileptogenesis. There is growing evidence that seizures also affect BBB, yet only scarce data is available regarding serum levels of BBB-associated proteins in chronic epilepsy. In this study, we aimed to assess serum levels of molecules associated with BBB in patients with epilepsy in the interictal period. Serum levels of MMP-9, MMP-2, TIMP-1, TIMP-2, S100B, CCL-2, ICAM-1, P-selectin, and TSP-2 were examined in a group of 100 patients who were seizure-free for a minimum of seven days and analyzed by ELISA. The results were compared with an age- and sex-matched control group. Serum levels of MMP-9, MMP-2, TIMP-1, TIMP-2 and S100B were higher in patients with epilepsy in comparison to control group (p < 0.0001; <0.0001; 0.001; <0.0001; <0.0001, respectively). Levels of CCL-2, ICAM-1, P-selectin and TSP-2 did not differ between the two groups. Serum levels of MMP-9, MMP-2, TIMP-1, TIMP-2 and S100B are elevated in patients with epilepsy in the interictal period, which suggests chronic processes of BBB disruption and restoration. The pathological process initiating epilepsy, in addition to seizures, is probably the factor contributing to the elevation of serum levels of the examined molecules.

The Crosstalk between the Blood–Brain Barrier Dysfunction and Neuroinflammation after General Anaesthesia

As we know, with continuous medical progress, the treatment of many diseases can be conducted via surgery, which often relies on general anaesthesia for its satisfactory performance. With the widespread use of general anaesthetics, people are beginning to question the safety of general anaesthesia and there is a growing interest in central nervous system (CNS) complications associated with anaesthetics. Recently, abundant evidence has suggested that both blood–brain barrier (BBB) dysfunction and neuroinflammation play roles in the development of CNS complications after anaesthesia. Whether there is a crosstalk between BBB dysfunction and neuroinflammation after general anaesthesia, and whether this possible crosstalk could be a therapeutic target for CNS complications after general anaesthesia needs to be clarified by further studies.

Transcriptomes of Clusterin- and S100B-transfected neuronal cells elucidate protective mechanisms against hypoxia and oxidative stress in the hooded seal (Cystophora cristata) brain

BACKGROUND

The hooded seal (Cystophora cristata) exhibits impressive diving skills and can tolerate extended durations of asphyxia, hypoxia and oxidative stress, without suffering from irreversible neuronal damage. Thus, when exposed to hypoxia in vitro, neurons of fresh cortical and hippocampal tissue from hooded seals maintained their membrane potential 4-5 times longer than neurons of mice. We aimed to identify the molecular mechanisms underlying the intrinsic neuronal hypoxia tolerance. Previous comparative transcriptomics of the visual cortex have revealed that S100B and clusterin (apolipoprotein J), two stress proteins that are involved in neurological disorders characterized by hypoxic conditions, have a remarkably high expression in hooded seals compared to ferrets. When overexpressed in murine neuronal cells (HN33), S100B and clusterin had neuroprotective effects when cells were exposed to hypoxia. However, their specific roles in hypoxia have remained largely unknown.

METHODS

In order to shed light on potential molecular pathways or interaction partners, we exposed HN33 cells transfected with either S100B, soluble clusterin (sCLU) or nuclear clusterin (nCLU) to normoxia, hypoxia and oxidative stress for 24 h. We then determined cell viability and compared the transcriptomes of transfected cells to control cells. Potential pathways and upstream regulators were identified via Gene Ontology (GO) and Ingenuity Pathway Analysis (IPA).

RESULTS

HN33 cells transfected with sCLU and S100B demonstrated improved glycolytic capacity and reduced aerobic respiration at normoxic conditions. Additionally, sCLU appeared to enhance pathways for cellular homeostasis to counteract stress-induced aggregation of proteins. S100B-transfected cells sustained lowered energy-intensive synaptic signaling. In response to hypoxia, hypoxia-inducible factor (HIF) pathways were considerably elevated in nCLU- and sCLU-transfected cells. In a previous study, S100B and sCLU decreased the amount of reactive oxygen species and lipid peroxidation in HN33 cells in response to oxidative stress, but in the present study, these functional effects were not mirrored in gene expression changes.

CONCLUSIONS

sCLU and S100B overexpression increased neuronal survival by decreasing aerobic metabolism and synaptic signaling in advance to hypoxia and oxidative stress conditions, possibly to reduce energy expenditure and the build-up of deleterious reactive oxygen species (ROS). Thus, a high expression of CLU isoforms and S100B is likely beneficial during hypoxic conditions.

The Role of the S100 Protein Family in Glioma

The S100 protein family consists of 25 members and share a common structure defined in part by the Ca²⁺ binding EF-hand motif. Multiple members' dysregulated expression is associated with progression, diagnosis and prognosis in a broad range of diseases, especially in tumors. They could exert wide range of functions both in intracellular and extracellular, including cell proliferation, cell differentiation, cell motility, enzyme activities, immune responses, cytoskeleton dynamics, Ca²⁺ homeostasis and angiogenesis. Gliomas are the most prevalent primary tumors of the brain and spinal cord with multiple subtypes that are diagnosed and classified based on histopathology. Up to now the role of several S100 proteins in gliomas have been explored. S100A8, S100A9 and S100B were highly expression in serum and may present as a marker correlated with survival and prognosis of glioma patients. Individual member was confirmed as a new regulator of glioma stem cells (GSCs) and a mediator of mesenchymal transition in glioblastoma (GBM). Additionally, several members up- or downregulation have been reported to involve in the development of glioma by interacting with signaling pathways and target proteins. Here we detail S100 proteins that are associated with glioma, and discuss their potential effects on progression, diagnosis and prognosis.

Ghrelin pretreatment enhanced the protective effect of bone marrow-derived mesenchymal stem cell-conditioned medium on lipopolysaccharide-induced endothelial cell injury

BACKGROUND

Lung endothelial barrier injury plays a crucial role in the pathophysiology of acute respiratory distress syndrome. It has been demonstrated that bone marrow-derived mesenchymal stem cells-conditioned medium (BMSCs-CM) and ghrelin have a protective effect. This study investigated if ghrelin pretreatment enhanced the protective effect of BMSCs-CM on lipopolysaccharide (LPS)-induced endothelial cell injury.

METHODS

BMSCs were isolated from rat bone marrow, expanded, then phenotypically tested for mesenchymal stem cell-identifying criteria by flow cytometry. The effects of the conditioned medium derived from ghrelin-pretreated BMSCs (BMSCs-^{ghrelin-pretreated}-CM) on LPS-injured endothelial cells were evaluated by migration, apoptosis, permeability, and pro-inflammatory factor (e.g., tumor necrosis factor-α, interleukin (IL)-1β, and IL-6) assays in endothelial cells. Further, AKT/GSK3β pathway activation in endothelial cells was examined by Western blot, and the gene expression profiles of ghrelin-pretreated BMSCs were examined by RNA sequencing.

RESULTS

BMSCs-^{ghrelin-pretreated}-CM had a greater protective effect on LPS-induced endothelial cell injury than BMSCs-CM by improving cell migration, alleviating apoptosis, and reducing endothelial permeability and the release of pro-inflammatory factors in endothelial cells. The mechanism is partly related to AKT/GSK3β pathway activation after BMSCs-^{ghrelin-pretreated}-CM treatment. There were five upregulated candidate genes (Wnt5a [i.e., Wnt Family Member 5A], S100b [i.e., S100 Calcium-Binding Protein B], Bmp2 [i.e., Bone Morphogenetic Protein 2], Id4 [i.e., Inhibitor Of DNA Binding 4], and PTHLH [i.e., Parathyroid Hormone Like Hormone]) in BMSCs after ghrelin treatment, and all were associated with AKT pathway activation and endothelial function.

CONCLUSIONS

Ghrelin pretreatment enhanced the protective effect of BMSCs-CM on LPS-induced endothelial cell injury, partly by activating the AKT/GSK3β pathway.

Glycolipid toxicity induces osteogenic dysfunction via the TLR4/S100B pathway

Diabetes can cause bone metabolism disorders and osteoporosis. The occurrence of both diabetes mellitus and osteoporosis increases the disability and mortality of elderly individuals due to pathological fracture. Abnormal metabolism of nutrientsis considered to be one of the important mechanisms of diabetes mellitus-induced osteoporosis. This study preliminarily explored the roles of TLR4 (Toll-like receptor 4) and S100B in osteogenic dysfunction induced by glycolipid toxicity. In this study, a diabetic rat model and TLR4-knockdown diabetic rat model were used in vivo. MC3T3-E1 cells in a high glucose and palmitic acid environment were used as glycolipid toxicity cell models in vitro. We investigated the effects of TLR4 and S100B on osteogenesis by overexpression or inhibition of TLR4 and S100B in vitro. We found that when TLR4 or S100B was inhibited, ALP and OCN were significantly up-regulated and p-ERK was significantly down regulated in the glycolipid model. These results suggest that TLR4/S100B may play a role in reducing glycolipid toxicity by regulating ERK phosphorylation.

The Impact of High Glucose or Insulin Exposure on S100B Protein Levels, Oxidative and Nitrosative Stress and DNA Damage in Neuron-Like Cells

Alzheimer’s disease (AD) is attracting considerable interest due to its increasing number of cases as a consequence of the aging of the global population. The mainstream concept of AD neuropathology based on pathological changes of amyloid β metabolism and the formation of neurofibrillary tangles is under criticism due to the failure of Aβ-targeting drug trials. Recent findings have shown that AD is a highly complex disease involving a broad range of clinical manifestations as well as cellular and biochemical disturbances. The past decade has seen a renewed importance of metabolic disturbances in disease-relevant early pathology with challenging areas in establishing the role of local micro-fluctuations in glucose concentrations and the impact of insulin on neuronal function. The role of the S100 protein family in this interplay remains unclear and is the aim of this research. Intracellularly the S100B protein has a protective effect on neurons against the toxic effects of glutamate and stimulates neurites outgrowth and neuronal survival. At high concentrations, it can induce apoptosis. The aim of our study was to extend current knowledge of the possible impact of hyper-glycemia and -insulinemia directly on neuronal S100B secretion and comparison to oxidative stress markers such as ROS, NO and DBSs levels. In this paper, we have shown that S100B secretion decreases in neurons cultured in a high-glucose or high-insulin medium, while levels in cell lysates are increased with statistical significance. Our findings demonstrate the strong toxic impact of energetic disturbances on neuronal metabolism and the potential neuroprotective role of S100B protein.

Growing role of S100B protein as a putative therapeutic target for neurological- and nonneurological-disorders

S100B is a calcium-binding protein mainly expressed by astrocytes, but also localized in other definite neural and extra-neural cell types. While its presence in biological fluids is widely recognized as a reliable biomarker of active injury, growing evidence now indicates that high levels of S100B are suggestive of pathogenic processes in different neural, but also extra-neural, disorders. Indeed, modulation of S100B levels correlates with the occurrence of clinical and/or toxic parameters in experimental models of diseases such as Alzheimer's and Parkinson's diseases, amyotrophic lateral sclerosis, muscular dystrophy, multiple sclerosis, acute neural injury, inflammatory bowel disease, uveal and retinal disorders, obesity, diabetes and cancer, thus directly linking the levels of S100B to pathogenic mechanisms. In general, deletion/inactivation of the protein causes the improvement of the disease, whereas its over-expression/administration induces a worse clinical presentation. This scenario reasonably proposes S100B as a common therapeutic target for several different disorders, also offering new clues to individuate possible unexpected connections among these diseases.

Metabolic Diseases and Down Syndrome: How Are They Linked Together?

Down syndrome is a genetic disorder caused by the presence of a third copy of chromosome 21, associated with intellectual disabilities. Down syndrome is associated with anomalies of both the nervous and endocrine systems. Over the past decades, dramatic advances in Down syndrome research and treatment have helped to extend the life expectancy of these patients. Improved life expectancy is obviously a positive outcome, but it is accompanied with the need to address previously overlooked complications and comorbidities of Down syndrome, including obesity and diabetes, in order to improve the quality of life of Down syndrome patients. In this focused review, we describe the associations between Down syndrome and comorbidities, obesity and diabetes, and we discuss the understanding of proposed mechanisms for the association of Down syndrome with metabolic disorders. Drawing molecular mechanisms through which Type 1 diabetes and Type 2 diabetes could be linked to Down syndrome could allow identification of novel drug targets and provide therapeutic solutions to limit the development of metabolic and cognitive disorders.

Emerging role of S100B protein implication in Parkinson's disease pathogenesis

The exact etiology of Parkinson's disease (PD) remains obscure, lacking effective diagnostic and prognostic biomarkers. In search of novel molecular factors that may contribute to PD pathogenesis, emerging evidence highlights the multifunctional role of the calcium-binding protein S100B that is widely expressed in the brain and predominantly in astrocytes. Preclinical evidence points towards the possible time-specific contributing role of S100B in the pathogenesis of neurodegenerative disorders including PD, mainly by regulating neuroinflammation and dopamine metabolism. Although existing clinical evidence presents some contradictions, estimation of S100B in the serum and cerebrospinal fluid seems to hold a great promise as a potential PD biomarker, particularly regarding the severity of motor and non-motor PD symptoms. Furthermore, given the recent development of S100B inhibitors that are able to cross the blood brain barrier, novel opportunities are arising in the research field of PD therapeutics. In this review, we provide an update on recent advances in the implication of S100B protein in the pathogenesis of PD and discuss relevant studies investigating the biomarker potential of S100B in PD, aiming to shed more light on clinical targeting approaches related to this incurable disorder.

Computational Design of Macrocyclic Binders of S100B(ββ): Novel Peptide Theranostics

S100B(ββ) proteins are a family of multifunctional proteins that are present in several tissues and regulate a wide variety of cellular processes. Their altered expression levels have been associated with several human diseases, such as cancer, inflammatory disorders and neurodegenerative conditions, and hence are of interest as a therapeutic target and a biomarker. Small molecule inhibitors of S100B(ββ) have achieved limited success. Guided by the wealth of available experimental structures of S100B(ββ) in complex with diverse peptides from various protein interacting partners, we combine comparative structural analysis and molecular dynamics simulations to design a series of peptides and their analogues (stapled) as S100B(ββ) binders. The stapled peptides were subject to in silico mutagenesis experiments, resulting in optimized analogues that are predicted to bind to S100B(ββ) with high affinity, and were also modified with imaging agents to serve as diagnostic tools. These stapled peptides can serve as theranostics, which can be used to not only diagnose the levels of S100B(ββ) but also to disrupt the interactions of S100B(ββ) with partner proteins which drive disease progression, thus serving as novel therapeutics.

S100B Impairs Oligodendrogenesis and Myelin Repair Following Demyelination Through RAGE Engagement

Increased expression of S100B and its specific receptor for advanced glycation end products (RAGE) has been described in patients with multiple sclerosis (MS), being associated with an active demyelinating process. We previously showed that a direct neutralization of S100B reduces lysophosphatidylcholine (LPC)-induced demyelination and inflammation using an ex vivo demyelinating model. However, whether S100B actions occur through RAGE and how oligodendrogenesis and remyelination are affected are not clarified. To evaluate the role of the S100B–RAGE axis in the course of a demyelinating insult, organotypic cerebellar slice cultures (OCSC) were demyelinated with LPC in the presence or absence of RAGE antagonist FPS-ZM1. Then, we explored the effects of the S100B–RAGE axis inhibition on glia reactivity and inflammation, myelination and neuronal integrity, and on oligodendrogenesis and remyelination. In the present study, we confirmed that LPC-induced demyelination increased S100B and RAGE expression, while RAGE antagonist FPS-ZM1 markedly reduced their content and altered RAGE cellular localization. Furthermore, FPS-ZM1 prevented LPC-induced microgliosis and astrogliosis, as well as NF-κB activation and pro-inflammatory cytokine gene expression. In addition, RAGE antagonist reduced LPC-induced demyelination having a beneficial effect on axonal and synaptic protein preservation. We have also observed that RAGE engagement is needed for LPC-induced oligodendrocyte (OL) maturation arrest and loss of mature myelinating OL, with these phenomena being prevented by FPS-ZM1. Our data suggest that increased levels of mature OL in the presence of FPS-ZM1 are related to increased expression of microRNAs (miRs) associated with OL differentiation and remyelination, such as miR-23a, miR-219a, and miR-338, which are defective upon LPC incubation. Finally, our electron microscopy data show that inhibition of the S100B–RAGE axis prevents axonal damage and myelin loss, in parallel with enhanced functional remyelination, as observed by the presence of thinner myelin sheaths when compared with Control. Overall, our data implicate the S100B–RAGE axis in the extent of myelin and neuronal damage, as well as in the inflammatory response that follows a demyelinating insult. Thus, prevention of RAGE engagement may represent a novel strategy for promoting not only inflammatory reduction but also neuronal and myelin preservation and/or remyelination, improving recovery in a demyelinating condition as MS.

Cellular and molecular mechanisms of sarcopenia: the S100B perspective

Primary sarcopenia is a condition of reduced skeletal muscle mass and strength, reduced agility, and increased fatigability and risk of bone fractures characteristic of aged, otherwise healthy people. The pathogenesis of primary sarcopenia is not completely understood. Herein, we review the essentials of the cellular and molecular mechanisms of skeletal mass maintenance; the alterations of myofiber metabolism and deranged properties of muscle satellite cells (the adult stem cells of skeletal muscles) that underpin the pathophysiology of primary sarcopenia; the role of the Ca²⁺ -sensor protein, S100B, as an intracellular factor and an extracellular signal regulating cell functions; and the functional role of S100B in muscle tissue. Lastly, building on recent results pointing to S100B as to a molecular determinant of myoblast-brown adipocyte transition, we propose S100B as a transducer of the deleterious effects of accumulation of reactive oxygen species in myoblasts and, potentially, myofibers concurring to the pathophysiology of sarcopenia.

Toward the Language Oscillogenome

Language has been argued to arise, both ontogenetically and phylogenetically, from specific patterns of brain wiring. We argue that it can further be shown that core features of language processing emerge from particular phasal and cross-frequency coupling properties of neural oscillations; what has been referred to as the language ‘oscillome.’ It is expected that basic aspects of the language oscillome result from genetic guidance, what we will here call the language ‘oscillogenome,’ for which we will put forward a list of candidate genes. We have considered genes for altered brain rhythmicity in conditions involving language deficits: autism spectrum disorders, schizophrenia, specific language impairment and dyslexia. These selected genes map on to aspects of brain function, particularly on to neurotransmitter function. We stress that caution should be adopted in the construction of any oscillogenome, given the range of potential roles particular localized frequency bands have in cognition. Our aim is to propose a set of genome-to-language linking hypotheses that, given testing, would grant explanatory power to brain rhythms with respect to language processing and evolution.

Post-Operative Cognitive Dysfunction: An exploration of the inflammatory hypothesis and novel therapies

Post-Operative Cognitive Dysfunction (POCD) is a highly prevalent condition with significant clinical, social and financial impacts for patients and their communities. The underlying pathophysiology is becoming increasingly understood, with the role of neuroinflammation and oxidative stress secondary to surgery and anaesthesia strongly implicated. This review aims to describe the putative mechanisms by which surgery-induced inflammation produces cognitive sequelae, with a focus on identifying potential novel therapies based upon their ability to modify these pathways.

S100A6 protein: functional roles

S100A6 protein belongs to the A group of the S100 protein family of Ca2+-binding proteins. It is expressed in a limited number of cell types in adult normal tissues and in several tumor cell types. As an intracellular protein, S100A6 has been implicated in the regulation of several cellular functions, such as proliferation, apoptosis, the cytoskeleton dynamics, and the cellular response to different stress factors. S100A6 can be secreted/released by certain cell types which points to extracellular effects of the protein. RAGE (receptor for advanced glycation endproducts) and integrin β1 transduce some extracellular S100A6's effects. Dosage of serum S100A6 might aid in diagnosis in oncology.

S100B promotes injury-induced vascular remodeling through modulating smooth muscle phenotype

S100B is a biomarker of nervous system injury, but it is unknown if it is also involved in vascular injury. In the present study, we investigated S100B function in vascular remodeling following injury. Balloon injury in rat carotid artery progressively induced neointima formation while increasing S100B expression in both neointimal vascular smooth muscle (VSMC) and serum along with an induction of proliferating cell nuclear antigen (PCNA). Knockdown of S100B by its shRNA delivered by adenoviral transduction attenuated the PCNA expression and neointimal hyperplasia in vivo and suppressed PDGF-BB-induced VSMC proliferation and migration in vitro. Conversely, overexpression of S100B promoted VSMC proliferation and migration. Mechanistically, S100B altered VSMC phenotype by decreasing the contractile protein expression, which appeared to be mediated by NF-κB activity. S100B induced NF-κB-p65 gene transcription, protein expression and nuclear translocation. Blockade of NF-κB activity by its inhibitor reversed S100B-mediated downregulation of VSMC contractile protein and increase in VSMC proliferation and migration. It appeared that S100B regulated NF-κB expression through, at least partially, the Receptor for Advanced Glycation End products (RAGE) because RAGE inhibitor attenuated S100B-mediated NF-κB promoter activity as well as VSMC proliferation. Most importantly, S100B secreted from VSMC impaired endothelial tube formation in vitro, and knockdown of S100B promoted re-endothelialization of injury-denuded arteries in vivo. These data indicated that S100B is a novel regulator for vascular remodeling following injury and may serve as a potential biomarker for vascular damage or drug target for treating proliferative vascular diseases.

S100B raises the alert in subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating disease with high mortality and mobility, the novel therapeutic strategies of which are essentially required. The calcium binding protein S100B has emerged as a brain injury biomarker that is implicated in pathogenic process of SAH. S100B is mainly expressed in astrocytes of the central nervous system and functions through initiating intracellular signaling or via interacting with cell surface receptor, such as the receptor of advanced glycation end products. The biological roles of S100B in neurons have been closely associated with its concentrations, resulting in either neuroprotection or neurotoxicity. The levels of S100B in the blood have been suggested as a biomarker to predict the progress or the prognosis of SAH. The role of S100B in the development of cerebral vasospasm and brain damage may result from the induction of oxidative stress and neuroinflammation after SAH. To get further insight into mechanisms underlying the role of S100B in SAH based on this review might help us to find novel therapeutic targets for SAH.

Overexpression of mutant dystrophin Dp71[INCREMENT]₇₈-₇₉ stimulates cell proliferation

Dp71 dystrophin is the main DMD gene product expressed in the central nervous system. Experiments using PC12 cells as a neuronal model have shown that Dp71 isoforms are involved in differentiation, adhesion, cell division, and nuclear architecture. To contribute to the knowledge of Dp71 domains function, we previously reported the isolation and partial characterization of the dystrophin Dp71[INCREMENT]78-79 (a mutant that lacks exons 71, 78, and 79), which stimulates the neuronal differentiation of PC12-C11 clone. In this article, we generated a doxycycline (Dox)-inducible expression system in PC12 Tet-On cells (B10 cells) to overexpress and control the transcription of Dp71[INCREMENT]78-79. Western blotting and confocal microscopy showed an increase in the amount of Dp71[INCREMENT]78-79 (217±75-fold) with the addition of Dox to growth medium. Cell proliferation assays and morphometric analyses demonstrated that Dp71[INCREMENT]78-79 increases the growth rate of B10 cells and reduces the nerve growth factor-neuronal differentiation. Western blotting analysis revealed an upregulation in the expression of proliferating cell nuclear antigen, focal adhesion kinase, and β-dystroglycan in B10 cells compared with control cells. Our results show that the inducible expression of Dp71[INCREMENT]78-79 increases the growth rate of PC12 Tet-On cells, suggesting a role of this protein in cell proliferation.

Effects of xanthine oxidase inhibition with febuxostat on the development of nephropathy in experimental type 2 diabetes

BACKGROUND AND PURPOSE

Elevated serum uric acid (UA) is a risk factor for the development of kidney disease. Inhibitors of xanthine oxidase (XOi), an enzyme involved in UA synthesis, have protective effects at early stages of experimental diabetic nephropathy (DN). However, long-term effects of XOi in models of DN remain to be determined.

EXPERIMENTAL APPROACH

The development of albuminuria, renal structure and molecular markers of DN were studied in type 2 diabetic Zucker obese (ZO) rats treated for 18 weeks with the XOi febuxostat and compared with vehicle-treated ZO rats, ZO rats treated with enalapril or a combination of both agents, and lean Zucker rats without metabolic defects.

RESULTS

Febuxostat normalized serum UA and attenuated the development of albuminuria, renal structural changes, with no significant effects on BP, metabolic control or systemic markers of oxidative stress (OS). Most of these actions were comparable with those of enalapril. Combination treatment induced marked decreases in BP and was more effective in ameliorating structural changes, expression of profibrotic genes and systemic OS than either monotherapy. Febuxostat attenuated renal protein expression of TGF-ß, CTGF, collagen 4, mesenchymal markers (FSP1 and vimentin) and a tissue marker of OS nitrotyrosine. Moreover, febuxostat attenuated TGF-ß- and S100B-induced increased expression of fibrogenic molecules in renal tubular cells in vitro in UA-free media in an Akt kinase-dependent manner.

CONCLUSIONS AND IMPLICATIONS

Febuxostat is protective and enhances the actions of enalapril in experimental DN. Multiple mechanisms might be involved, such as a reduction of UA, renal OS and inhibition of profibrotic signalling.

Conditioning solid tumor microenvironment through inflammatory chemokines and S100 family proteins

Recently, there has been growing attention to the role of the tumor microenvironment (TME) in cancer growth, metastasis and emergence of chemotherapy resistance. Stromal and tumor cells make up the TME and interact with each other through a complex cross-talk manner. This interaction is facilitated by a variety of growth factors, cytokines, chemokines and S100 proteins. In this review, we focus on chemokines and their cognate receptors in regulating the tumorigenic process. Chemokines are cytokines that have chemotactic potential. Chemokine receptors are expressed on tumor cells and stromal cells. Chemokines and their cognate receptors modulate tumor growth and metastasis in a paracrine and autocrine manner. They play a major role in the modulation of stromal cell recruitment, angiogenic potential, cancer cell proliferation, survival, adhesion, invasion and metastasis to distant sites. In addition, a new class of calcium binding family S100 proteins has been getting attention as they play significant roles in tumor progression and metastasis by modulating TME. Here, we highlight recent developments regarding the inflammatory chemokine/S100 protein systems in the TME. We also focus on how chemokines/S100 proteins, through their role in the TME, modulate cancer cell ability to grow, proliferate, invade and metastasize to different organs. This review highlights the possibility of using the chemokine/chemokine receptor axis as a promising strategy in cancer therapy, the current difficulties in achieving this goal, and how it could be overcome for successful future therapeutic intervention.

S100B-p53 disengagement by pentamidine promotes apoptosis and inhibits cellular migration via aquaporin-4 and metalloproteinase-2 inhibition in C6 glioma cells

S100 calcium-binding protein B (S100B) is highly expressed in glioma cells and promotes cancer cell survival via inhibition of the p53 protein. In melanoma cells, this S100B-p53 interaction is known to be inhibited by pentamidine isethionate, an antiprotozoal agent. Thus, the aim of the present study was to evaluate the effect of pentamidine on rat C6 glioma cell proliferation, migration and apoptosis in vitro. The change in C6 cell proliferation following treatment with pentamidine was determined by performing a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide-formazan assay. Significant dose-dependent decreases in proliferation were observed at pentamidine concentrations of 0.05 µM (58.5±5%; P<0.05), 0.5 µM (40.6±7%; P<0.01) and 5 µM (13±4%; P<0.001) compared with the control (100% viability). Furthermore, treatment with 0.05, 0.5 and 5 µM pentamidine was associated with a significant increase in apoptosis versus the untreated cells, as determined by DNA fragmentation assays, immunofluorescence analysis of C6 chromatin using Hoechst staining, and immunoblot analysis of B-cell lymphoma-2 (Bcl-2)-associated X protein (100%, P<0.05; 453%, P<0.01; and 1000%, P<0.001, respectively) and Bcl-2 (-60%, P<0.001; -80.13%, P<0.001; -95%, P<0.001, respectively). In addition, the administration of 0.05, 0.5 and 5 µM pentamidine significantly upregulated the protein expression levels of p53 (681±87.5%, P<0.05; 1244±94.3%, P<0.01; and 2244±111%, P<0.001, respectively), and significantly downregulated the expression levels of matrix metalloproteinase-2 (42±2.3%, P<0.05; 71±2.5%, P<0.01; and 95.8±3.3%, P<0.001, respectively) and aquaporin 4 (38±2.5%, P<0.05; 69±2.6%, P<0.01; and 88±3.0%, P<0.001, respectively), compared with the untreated cells. The wound healing assay demonstrated that cell migration was significantly impaired by treatment with 0.05, 0.5 and 5 µM pentamidine compared with untreated cells (88±4.2%, P<0.05; 64±2%, P<0.01; and 42±3.1%, P<0.001, respectively). Although additional in vivo studies are required to clarify the current in vitro data, the present study indicates that pentamidine and S100B-p53 inhibitors may represent a novel approach for the treatment of glioma.

SOX10 transactivates S100B to suppress Schwann cell proliferation and to promote myelination

Schwann cells are an important cell source for regenerative therapy for neural disorders. We investigated the role of the transcription factor sex determining region Y (SRY)-box 10 (SOX10) in the proliferation and myelination of Schwann cells. SOX10 is predominantly expressed in rat sciatic nerve-derived Schwann cells and is induced shortly after birth. Among transcription factors known to be important for the differentiation of Schwann cells, SOX10 potently transactivates the S100B promoter. In cultures of Schwann cells, overexpressing SOX10 dramatically induces S100B expression, while knocking down SOX10 with shRNA suppresses S100B expression. Here, we identify three core response elements of SOX10 in the S100B promoter and intron 1 with a putative SOX motif. Knockdown of either SOX10 or S100B enhances the proliferation of Schwann cells. In addition, using dissociated cultures of dorsal root ganglia, we demonstrate that suppressing S100B with shRNA impairs myelination of Schwann cells. These results suggest that the SOX10-S100B signaling axis critically regulates Schwann cell proliferation and myelination, and therefore is a putative therapeutic target for neuronal disorders.

S100B as a potential biomarker for the detection of cytotoxicity of melanocytes

Skin irritation is one of the most common adverse reactions in hydroquinone (HQ) and retinoic acid (RA). Although melanocytes have rarely been considered to be involved in skin irritation, RA and particularly HQ could induce melanocyte toxicity, resulting in depigmentation. We chose S100B as a candidate gene for melanocytotoxicity from a genome-wide transcriptional profiling analysis after applying irritant doses of HQ, RA and sodium lauryl sulphate (SLS) to cultures of keratinocytes and/or melanocytes. In this study, the role of S100B on melanocyte viability and cytotoxicity was examined. S100B was detected in melanocytes, but not in keratinocytes or fibroblasts. Melanocytes after treatment with increasing concentrations of HQ, RA, SLS and urushiol showed significant increases in intracellular and extracellular S100B expression with reduced viable cell number and increased release of lactate dehydrogenase. No RAGE expression and no significant function of CD166/ALCAM in melanocyte survival and cytotoxicity favoured the role of intracellular S100B in chemically irritated melanocytes. S100B knock-down increased apoptosis through inhibition of PI3K/AKT, NF-κB and ERK activation, suggesting the increased intracellular S100B expression by chemical irritation as a compensatory reaction to reduce cytotoxicity. The numerical decrease in S100B/c-kit-double-positive melanocytes was also examined in human skin epidermis irritated by HQ or RA with stronger staining intensities of S100B. Collectively, the decrease in viable cell number by reduced intracellular S100B levels in vitro and by chemical irritation in vivo suggests that S100B could be a potential biomarker for melanocytes cytotoxicity.

Functions of S100 proteins

The S100 protein family consists of 24 members functionally distributed into three main subgroups: those that only exert intracellular regulatory effects, those with intracellular and extracellular functions and those which mainly exert extracellular regulatory effects. S100 proteins are only expressed in vertebrates and show cell-specific expression patterns. In some instances, a particular S100 protein can be induced in pathological circumstances in a cell type that does not express it in normal physiological conditions. Within cells, S100 proteins are involved in aspects of regulation of proliferation, differentiation, apoptosis, Ca2+ homeostasis, energy metabolism, inflammation and migration/invasion through interactions with a variety of target proteins including enzymes, cytoskeletal subunits, receptors, transcription factors and nucleic acids. Some S100 proteins are secreted or released and regulate cell functions in an autocrine and paracrine manner via activation of surface receptors (e.g. the receptor for advanced glycation end-products and toll-like receptor 4), G-protein-coupled receptors, scavenger receptors, or heparan sulfate proteoglycans and N-glycans. Extracellular S100A4 and S100B also interact with epidermal growth factor and basic fibroblast growth factor, respectively, thereby enhancing the activity of the corresponding receptors. Thus, extracellular S100 proteins exert regulatory activities on monocytes/macrophages/microglia, neutrophils, lymphocytes, mast cells, articular chondrocytes, endothelial and vascular smooth muscle cells, neurons, astrocytes, Schwann cells, epithelial cells, myoblasts and cardiomyocytes, thereby participating in innate and adaptive immune responses, cell migration and chemotaxis, tissue development and repair, and leukocyte and tumor cell invasion.

S100A11 is involved in the regulation of the stability of cell cycle regulator p21(CIP1/WAF1) in human keratinocyte HaCaT cells

The cyclin-dependent kinase inhibitor p21(CIP1/WAF1) is a regulatory factor of the cell cycle. Its transcriptional activation and protein stability are tightly controlled by several distinct mechanisms. S100A11 is a member of the S100 family of Ca²⁺-binding proteins involved in several biological processes, including cell cycle progression and signal transduction. In the present study, we show that down-regulation of S100A11 results in the reduction of p21 protein in human HaCaT keratinocytes. It appears that a ubiquitin-independent proteasomal degradation process is involved in p21 degradation in S100A11 down-regulated cells. The application of a proteasome inhibitor stabilized p21 protein in these cells. Analysis of distinct signal transduction pathways revealed a disturbed phosphatidylinositol-3-kinase/Akt pathway after S100A11 knockdown. We determined that the glycogen synthase kinase-3, which is negatively regulated by phosphatidylinositol 3-kinase/Akt, was activated in cells possessing knocked-down S100A11 and appears to be involved in p21 protein destabilization. The application of a specific inhibitor of glycogen synthase kinase 3 resulted in an increase of the p21 protein level in S100A11 down-regulated HaCaT cells. Glycogen synthase kinase 3 is able to phosphorylate p21 at T57, which induces p21 proteasomal turnover. Mutation of the glycogen synthase kinase 3 site threonine 57 into alanine (T57A) stabilizes p21 in HaCaT cells lacking S100A11. Beside decreased p21 protein, down-regulation of S100A11 triggered the induction of apoptosis in HaCaT cells. These observations suggest that S100A11 is involved in the maintenance of p21 protein stability and appears to function as an inhibitor of apoptosis in human HaCaT keratinocyte cells. Thus, the data shed light on a novel pathway regulating p21 protein stability.

The evolution of S100B inhibitors for the treatment of malignant melanoma

Malignant melanoma continues to be an extremely fatal cancer due to a lack of viable treatment options for patients. The calcium-binding protein S100B has long been used as a clinical biomarker, aiding in malignant melanoma staging and patient prognosis. However, the discovery of p53 as a S100B target and the consequent impact on cell apoptosis redirected research efforts towards the development of inhibitors of this S100B-p53 interaction. Several approaches, including computer-aided drug design, fluorescence polarization competition assays, NMR, x-ray crystallography and cell-based screens have been performed to identify compounds that block the S100B-p53 association, reactivate p53 transcriptional activities and induce cancer cell death. Eight promising compounds, including pentamidine, are presented in this review and the potential for future modifications is discussed. Synthesis of compound derivatives will likely exhibit increased S100B affinity and mimic important S100B-target dynamic properties that will result in high specificity.

S100B promotes glioma growth through chemoattraction of myeloid-derived macrophages

PURPOSE

S100B is member of a multigenic family of Ca(2+)-binding proteins, which is overexpressed by gliomas. Recently, we showed that low concentrations of S100B attenuated microglia activation through the induction of Stat3. We hypothesized that overexpression of S100B in gliomas could promote tumor growth by modulating the activity of tumor-associated macrophages (TAM).

EXPERIMENTAL DESIGN

We stably transfected GL261 glioma cell lines with constructs that overexpressed (S100B(high)) or underexpressed (S100B(low)) S100B and compared their growth characteristics to intracranial wild-type (S100B(wt)) tumors.

RESULTS

Downregulation of S100B in gliomas had no impact on cell division in vitro but abrogated tumor growth in vivo. Interestingly, compared to S100B(low) tumors, S100B(wt) and S100B(high) intracranial gliomas exhibited higher infiltration of TAMs, stronger inflammatory cytokine expression, and increased vascularity. To identify the potential mechanisms involved, the expression of the S100B receptor, receptor for advanced glycation end products (RAGE), was evaluated in gliomas. Although S100B expression induced RAGE in vivo, RAGE ablation in mice did not significantly inhibit TAM infiltration into gliomas, suggesting that other pathways were involved in this process. To evaluate other mechanisms responsible for TAM chemoattraction, we then examined chemokine pathways and found that C-C motif ligand 2 (CCL2) was upregulated in S100B(high) tumors. Furthermore, analysis of The Cancer Genome Atlas's glioma data bank showed a positive correlation between S100B and CCL2 expression in human proneural and neural glioma subtypes, supporting our finding.

CONCLUSIONS

These observations suggest that S100B promotes glioma growth by TAM chemoattraction through upregulation of CCL2 and introduces the potential utility of S100B inhibitors for glioma therapy.

S100B protein in tissue development, repair and regeneration

The Ca²⁺-binding protein of the EF-hand type, S100B, exerts both intracellular and extracellular regulatory activities. As an intracellular regulator, S100B is involved in the regulation of energy metabolism, transcription, protein phosphorylation, cell proliferation, survival, differentiation and motility, and Ca²⁺ homeostasis, by interacting with a wide array of proteins (i.e., enzymes, enzyme substrates, cytoskeletal subunits, scaffold/adaptor proteins, transcription factors, ubiquitin E3 ligases, ion channels) in a restricted number of cell types. As an extracellular signal, S100B engages the pattern recognition receptor, receptor for advanced glycation end-products (RAGE), on immune cells as well as on neuronal, astrocytic and microglial cells, vascular smooth muscle cells, skeletal myoblasts and cardiomyocytes. However, RAGE may not be the sole receptor activated by S100B, the protein being able to enhance bFGF-FGFR1 signaling by interacting with FGFR1-bound bFGF in particular cell types. Moreover, extracellular effects of S100B vary depending on its local concentration. Increasing evidence suggests that at the concentration found in extracellular fluids in normal physiological conditions and locally upon acute tissue injury, which is up to a few nM levels, S100B exerts trophic effects in the central and peripheral nervous system and in skeletal muscle tissue thus participating in tissue homeostasis. The present commentary summarizes results implicating intracellular and extracellular S100B in tissue development, repair and regeneration.

S100 calcium binding proteins and ion channels

S100 Ca(2+)-binding proteins have been associated with a multitude of intracellular Ca(2+)-dependent functions including regulation of the cell cycle, cell differentiation, cell motility and apoptosis, modulation of membrane-cytoskeletal interactions, transduction of intracellular Ca(2+) signals, and in mediating learning and memory. S100 proteins are fine tuned to read the intracellular free Ca(2+) concentration and affect protein phosphorylation, which makes them candidates to modulate certain ion channels and neuronal electrical behavior. Certain S100s are secreted from cells and are found in extracellular fluids where they exert unique extracellular functions. In addition to their neurotrophic activity, some S100 proteins modulate neuronal electrical discharge activity and appear to act directly on ion channels. The first reports regarding these effects suggested S100-mediated alterations in Ca(2+) fluxes, K(+) currents, and neuronal discharge activity. Recent reports revealed direct and indirect interactions with Ca(2+), K(+), Cl(-), and ligand activated channels. This review focuses on studies of the physical and functional interactions of S100 proteins and ion channels.

The S100B protein in biological fluids: more than a lifelong biomarker of brain distress

S100B is a calcium-binding protein concentrated in glial cells, although it has also been detected in definite extra-neural cell types. Its biological role is still debated. When secreted, S100B is believed to have paracrine/autocrine trophic effects at physiological concentrations, but toxic effects at higher concentrations. Elevated S100B levels in biological fluids (CSF, blood, urine, saliva, amniotic fluid) are thus regarded as a biomarker of pathological conditions, including perinatal brain distress, acute brain injury, brain tumors, neuroinflammatory/neurodegenerative disorders, psychiatric disorders. In the majority of these conditions, high S100B levels offer an indicator of cell damage when standard diagnostic procedures are still silent. The key question remains as to whether S100B is merely leaked from injured cells or is released in concomitance with both physiological and pathological conditions, participating at high concentrations in the events leading to cell injury. In this respect, S100B levels in biological fluids have been shown to increase in physiological conditions characterized by stressful physical and mental activity, suggesting that it may be physiologically regulated and raised during conditions of stress, with a putatively active role. This possibility makes this protein a candidate not only for a biomarker but also for a potential therapeutic target.

Gene expression pattern in PC12 cells with reduced PMCA2 or PMCA3 isoform: selective up-regulation of calmodulin and neuromodulin

Cellular calcium homeostasis is controlled predominantly by the plasma membrane calcium pump (PMCA). From four PMCA isoforms, PMCA1 and PMCA4 are ubiquitous, while PMCA2 and PMCA3 are found in excitable cells. We have previously shown that suppression of neuron-specific PMCAs in non-differentiated PC12 cells changed the cell morphology and triggered neuritogenesis. Using the microarrays, real-time PCR and immunodetection, we analyzed the effect of PMCA2 or PMCA3 reduction in PC12 cells on gene expression, with emphasis on calmodulin (CaM), neuromodulin (GAP43) and MAP kinases. In PMCA-suppressed lines total CaM increased, and the calm I and calm II genes appeared to be responsible for this effect. mRNA and protein levels of GAP43 were increased, however, the amount of phosphorylated form was lower than in control cells. Localization of CaM/GAP43 and CaM/pGAP43 differed between control and PMCA-reduced cells. In both PMCA-modified lines, amounts of ERK1/2 increased. While pERK1 decreased, the pERK2 level was similar in all examined lines. PMCA suppression did not change the p38 amount, but the p-p38 diminished. JNK2 protein decreased in both PMCA-reduced cells without changes in pJNK level. Microarray analysis revealed distinct expression patterns of certain genes involved in the regulation of cell cycle, proliferation, migration, differentiation, apoptosis and cell signaling. Suppression of neuron-specific PMCA isoforms affected the phenotype of PC12 cells enabling adaptation to the sustained increase in cytosolic Ca(2+) concentration. This is the first report showing function of PMCA2 and PMCA3 isoforms in the regulation of signaling pathways in PC12 cells.

Improvement of Memory by Means of Ultra-Low Doses of Antibodies to S-100B Antigen

Antigen S-100B of nervous tissue, according to the data of numerous studies, affects the mechanisms of nervous system plasticity and memory. The influence of ultralow doses of antibodies to S-100B (6C dilution, according to the homeopathic pharmacopoeia) has been studied on three learning behavioral models on Wistar rats, which were inhibitory avoidance, choosing of bowls with sucrose and feeding behavior cessation after auditory signal. For all three tasks, parameters of reproduction of the learned skills improved after per oral administration of potentiated antibodies to S-100B antigen immediately after learning. Possible mechanisms of the anti-S-100B antibodies influence on memory formation are discussed.

S100B attenuates microglia activation in gliomas: possible role of STAT3 pathway

Despite significant infiltration into tumors, the effector function of macrophages (MPs) and microglia (MG) appears to be suppressed in gliomas. Although STAT3 pathway is thought to play a role in this process, the exact mechanism by which gliomas induce STAT3 activation in MPs and MG is not known. Because activation of receptor for advanced glycation end products (RAGE) can induce STAT3, and because gliomas express high levels of S100B, a RAGE ligand, we hypothesized that MP/MG STAT3 activity may be modulated through S100B-RAGE interaction. Exposure of N9 MG and bone marrow-derived monocytes (BMM) to GL261 glioma condition medium (GCM) and low (nM) levels of S100B increased RAGE expression, induced STAT3 and suppressed MG function in vitro. Furthermore, neutralization of S100B in GCM, partially reversed IL-1β suppression in BMM, suggesting that the inhibitory effect of GCM to be in part due to S100B. Finally, blockage of S100B-RAGE interaction inhibited STAT3 activation in N9 MG and in glioma MG/MP in vivo. These findings suggest that the RAGE pathway may play an important role in STAT3 induction in glioma-associated MG/MPs, and that this process may be mediated through S100B.

S100B in myoblasts regulates the transition from activation to quiescence and from quiescence to activation and reduces apoptosis

S100B protein activates IKKβ/NF-κB within myoblasts, thereby inhibiting the expression of MyoD and the MyoD-downstream effectors, myogenin and p21(WAF1), and myoblast differentiation. Herein we show that myoblasts downregulate S100B expression once transferred from proliferation medium to differentiation medium via a p38 MAPK-driven transcriptional mechanism as well as a post-translational, proteasome-dependent mechanism, and that myoblasts that have not been committed to differentiation resume expressing S100B once transferred back to proliferation medium. Likewise, myoblasts downregulate S100B expression once transferred to quiescence medium, and interference with S100B downregulation as obtained by stable overexpression of the protein results in reduced acquisition of quiescence and a faster proliferation upon transfer of the cells from quiescence medium to proliferation medium, compared to controls. These latter effects are dependent on S100B-induced activation of JNK. Moreover, S100B reduces myoblast apoptosis in an MEK-ERK1/2, Akt, JNK, and NF-κB-dependent manner. However, myogenin(+) myoblasts (i.e., myocytes) and myotubes abundantly express S100B likely induced by myogenin. Our results suggest that (1) a timely repression of S100B expression is required for efficient myogenic differentiation; (2) S100B plays an important role in the expansion of the activated (i.e., proliferating) myoblast population; (3) under conditions associated with enhanced expression of S100B, the transition from proliferation to quiescence and from quiescence to proliferation might be altered; and (4) S100B exerts different regulatory effects in myoblasts and myocytes/myotubes/myofibers. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.

S100B Protein, A Damage-Associated Molecular Pattern Protein in the Brain and Heart, and Beyond

S100B belongs to a multigenic family of Ca(2+)-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), Ca(2+) 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.

S100B protein in myoblasts modulates myogenic differentiation via NF-kappaB-dependent inhibition of MyoD expression

S100B, a Ca(2+)-binding protein of the EF-hand type, is expressed in myoblasts, the precursors of skeletal myofibers, and muscle satellite cells (this work). S100B has been shown to participate in the regulation of several intracellular processes including cell cycle progression and differentiation. We investigated regulatory activities of S100B within myoblasts by stable overexpression of S100B and by inhibition of S100B expression. Overexpression of S100B in myoblast cell lines and primary myoblasts resulted in inhibition of myogenic differentiation, evidenced by lack of expression of myogenin and myosin heavy chain (MyHC) and absence of myotube formation. S100B-overexpressing myoblasts showed reduced MyoD expression levels and unchanged Myf5 expression levels, compared with control myoblasts, and transient transfection of S100B-overexpressing myoblasts with MyoD, but not Myf5, restored differentiation and fusion in part. The transcriptional activity of NF-kappaB, a negative regulator of MyoD expression, was enhanced in S100B-overexpressing myoblasts, and blocking NF-kappaB activity resulted in reversal of S100B's inhibitory effects. Yin Yang1, a transcriptional repressor that is induced by NF-kappaB (p65) and mediates NF-kappaB inhibitory effects on several myofibrillary genes, also was upregulated in S100B-overexpressing myoblasts. Conversely, silencing S100B expression in myoblast cell lines by RNA interference resulted in reduced NF-kappaB activity and enhanced MyoD, myogenin and MyHC expression and myotube formation. Thus, intracellular S100B might modulate myoblast differentiation by interfering with MyoD expression in an NF-kappaB-dependent manner.

Antibodies to S100 proteins have anxiolytic-like activity at ultra-low doses in the adult rat

S100 proteins are small calcium-binding proteins interacting with numerous intra- and extra cellular targets involved in diverse physiological functions. In particular, S100 proteins may be involved in the regulation of anxiety-related behaviour. In the present study, the effects of affinity-purified antibodies to S100 proteins administered orally at ultra-low doses were evaluated in pre-clinical tests for anxiolytic-like activity in the adult rat. In the Vogel conflict test in the rat, antibodies to S100 proteins increased punished drinking (anti-conflict effect) at 5 and 7.5 mL kg−1, but not at 2.5 or 10 mL kg−1. Antibodies to S100 proteins increased the percentage of entries into the open arms of an elevated plus-maze at 10 mL kg−1, but not at lower doses. Taken together, these results indicate the presence of anxiolytic-like activity for antibodies to S100 proteins over the dose range 5–10 mL kg−1 in the adult rat.

S100A11: diverse function and pathology corresponding to different target proteins

S100A11, as a member of S100 protein family, while featuring the common identities as the other EF-hand Ca(2+)-binding family members, has its own individual characteristics. S100A11 is widely expressed in multiple tissues, and is located in cytoplasm, nucleus, and even cell periphery. S100A11 exists as a non-covalent homodimer with an antiparallel conformation. Ca(2+) binding to S100A11 would trigger conformational changes which would expose the hydrophobic cleft of S100A11 and facilitate its interaction with target proteins. Since S100A11 appears to lack enzymatic activity, in this article, corresponding to a variety of its target proteins, we systematically describe the biological roles of S100A11 and its possible mechanism in the processes of inflammation, regulation of enzyme activity, and cell growth regulation. As a dual cell growth mediator, S100A11 acts as either a tumor suppressor or promoter in many different types of tumors and would play respective roles in influencing the proliferation of the cancer cells. We intend to illustrate the biological function of the S100 protein, and shed light on the further research, which will provide us with a better understanding of it.

S100B Protein Regulates Astrocyte Shape and Migration via Interaction with Src Kinase: IMPLICATIONS FOR ASTROCYTE DEVELOPMENT, ACTIVATION, AND TUMOR GROWTH

S100B is a Ca(2+)-binding protein of the EF-hand type that is abundantly expressed in astrocytes and has been implicated in the regulation of several intracellular activities, including proliferation and differentiation. We show here that reducing S100B levels in the astrocytoma cell line GL15 and the Müller cell line MIO-M1 by small interference RNA technique results in a rapid disassembly of stress fibers, collapse of F-actin onto the plasma membrane and reduced migration, and acquisition of a stellate shape. Also, S100B-silenced GL15 and MIO-M1 Müller cells show a higher abundance of glial fibrillary acidic protein filaments, which mark differentiated astrocytes, compared with control cells. These effects are dependent on reduced activation of the phosphatidylinositol 3-kinase (PI3K) downstream effectors, Akt and RhoA, and consequently elevated activity of GSK3beta and Rac1 and decreased activity of the RhoA-associated kinase. Also, rat primary astrocytes transiently down-regulate S100B expression when exposed to the differentiating agent dibutyryl cyclic AMP and re-express S100B at later stages of dibutyryl cyclic AMP-induced differentiation. Moreover, reducing S100B levels results in a remarkably slow resumption of S100B expression, suggesting the S100B might regulate its own expression. Finally, we show that S100B interacts with Src kinase, thereby stimulating the PI3K/Akt and PI3K/RhoA pathways. These results suggest that S100B might contribute to reduce the differentiation potential of cells of the astrocytic lineage and participate in the astrocyte activation process in the case of brain insult and in invasive properties of glioma cells.