Expression of angiogenic factor Cyr61 during neuronal cell death via the activation of c-Jun N-terminal kinase and serum response factor

CCN-Hippo YAP signaling in vision and its role in neuronal, glial and vascular cell function and behavior

The retina is a highly specialized tissue composed of a network of neurons, glia, and vascular and epithelial cells; all working together to coordinate and transduce visual signals to the brain. The retinal extracellular matrix (ECM) shapes the structural environment in the retina but also supplies resident cells with proper chemical and mechanical signals to regulate cell function and behavior and maintain tissue homeostasis. As such, the ECM affects virtually all aspects of retina development, function and pathology. ECM-derived regulatory cues influence intracellular signaling and cell function. Reversibly, changes in intracellular signaling programs result in alteration of the ECM and downstream ECM-mediated signaling network. Our functional studies in vitro, genetic studies in mice, and multi omics analyses have provided evidence that a subset of ECM proteins referred to as cellular communication network (CCN) affects several aspects of retinal neuronal and vascular development and function. Retinal progenitor, glia and vascular cells are major sources of CCN proteins particularly CCN1 and CCN2. We found that expression of the CCN1 and CCN2 genes is dependent on the activity of YAP, the core component of the hippo-YAP signaling pathway. Central to the Hippo pathway is a conserved cascade of inhibitory kinases that regulate the activity of YAP, the final transducer of this pathway. Reversibly, YAP expression and/or activity is dependent on CCN1 and CCN2 downstream signaling, which creates a positive or negative feedforward loop driving developmental processes (e.g., neurogenesis, gliogenesis, angiogenesis, barriergenesis) and, when dysregulated, disease progression in a range of retinal neurovascular disorders. Here we describe mechanistic hints involving the CCN-Hippo-YAP regulatory axis in retina development and function. This regulatory pathway represents an opportunity for targeted therapies in neurovascular and neurodegenerative diseases. The CCN-YAP regulatory loop in development and pathology.

The CREB and AP-1-Dependent Cell Communication Network Factor 1 Regulates Porcine Epidemic Diarrhea Virus-Induced Cell Apoptosis Inhibiting Virus Replication Through the p53 Pathway

Porcine epidemic diarrhea virus (PEDV) infection causes severe diarrhea, dehydration, and high mortality in sick pigs, causing huge economic losses to the pig industry. However, the relationship between cell communication network factor 1 (CCN1) and PEDV infection has not been reported. In this study, we showed that the expression of CCN1 was enhanced by PEDV infection, and we observed that PEDV promotes the CREB and AP-1 activation to promote CCN1 expression. The PKA and p38 inhibitors significantly suppress CCN1 expression, indicating that PEDV-induced CCN1 expression may be through PKA and p38 pathway. Further tests confirmed that CREB and AP-1 are regulated by PKA and p38, respectively. Overexpression of CCN1 decreased the replication of PEDV, whereas knockdown of CCN1 increased the replication of PEDV. We proved that the overexpression of CCN1 increased the phosphorylation level of p53, promoted the expresion of Bax and the cleavage of caspase 9 and caspase 3, and inhibited the production of Bcl-2. CCN1 knockdown decreased the phosphorylation level of p53, inhibited the production of Bax and the cleavage of caspase 9 and caspase 3, and promoted the expression of Bcl-2. The treatment of PFT-α (p53 inhibitor) significantly suppressed the expression of cleaved caspase 9 and caspase 3, leading to the decrease of apoptosis. Together, these studies showed that PEDV promotes the activation of CREB and AP-1 to increase the expression of CCN1. Overexpression of CCN1 promotes apoptosis by elevating p53 protein phosphorylation and inhibits PEDV replication, and knockdown of CCN1 inhibits apoptosis by decreasing p53 protein phosphorylation and promotes PEDV replication. Our study could provide some reference for the molecular mechanisms of PEDV-induced CCN1 induction and supply a new therapeutic target for PEDV.

L-Arginine Exerts Excellent Anti-Stress Effects on Stress-Induced Shortened Lifespan, Cognitive Decline and Depression

The anti-stress potential of dietary L-arginine (Arg) was assessed in psychosocially stress-loaded senescence-accelerated (SAMP10) mice. Although this strain of mouse is sensitive to stress, daily administration of Arg at 3 mg/kg significantly suppressed aging-related cognitive decline and behavioral depression at nine months of age and counteracted stress-induced shortened lifespan. To investigate the mechanism of the anti-stress effect of Arg in the brain, early changes in oxidative damage and gene expression levels were measured using SAMP10 mice that were stress-loaded for three days. Increased lipid peroxidation in the brains of stressed mice was significantly lowered by Arg intake. Several genes associated with oxidative stress response and neuronal excitotoxic cell death, including Nr4a1, Arc, and Cyr61, remarkably increased in response to psychosocial stress; however, their expression was significantly suppressed in mice that ingested Arg even under stress conditions. In contrast, the genes that maintain mitochondrial functions and neuronal survival, including Hba-a2 and Hbb-b2, were significantly increased in mice that ingested Arg. These results indicate that Arg reduces oxidative damage and enhances mitochondrial functions in the brain. We suggest that the daily intake of Arg plays important roles in reducing stress-induced brain damage and slowing aging.

Expression of ACE2 and a viral virulence-regulating factor CCN family member 1 in human iPSC-derived neural cells: implications for COVID-19-related CNS disorders

It has been reported that coronavirus disease 2019 (COVID-19) causes not only pneumonia but also systemic inflammations including central nervous system (CNS) disorders. However, little is known about the mechanism that triggers the COVID-19-associated CNS disorders, due to the lack of appropriate experimental systems. Our present study showed that angiotensin-converting enzyme-2 (ACE2), a cellular receptor for SARS-CoV-2, is expressed in human induced pluripotent stem cell (iPSC)-derived neural stem/progenitor cells (hiPSC-NS/PCs) and young neurons. Furthermore, together with database analysis, we found that a viral virulent factor CCN family member 1 (CCN1), which is known to be induced by SARS-CoV-2 infection, is expressed in these cells at basal levels. Considering the role of CCN1 which is known to be involved in viral toxicity and inflammation, hiPSC-NS/PCs could provide an excellent model for COVID-19-associated CNS disorders from the aspect of SARS-CoV-2 infection-ACE2-CCN1 axis. In addition, we identified compounds that reduce CCN1 expression. Collectively, our study using hiPSC-NS/PCs may aid in the development of a therapeutic target for COVID-19-related CNS disorders.

Transcriptome Analysis Reveals Distinct Responses to Physiologic versus Toxic Manganese Exposure in Human Neuroblastoma Cells

Manganese (Mn) is an essential trace element, which also causes neurotoxicity in exposed occupational workers. Mn causes mitochondrial toxicity; however, little is known about transcriptional responses discriminated by physiological and toxicological levels of Mn. Identification of such mechanisms could provide means to evaluate risk of Mn toxicity and also potential avenues to protect against adverse effects. To study the Mn dose-response effects on transcription, analyzed by RNA-Seq, we used human SH-SY5Y neuroblastoma cells exposed for 5 h to Mn (0 to 100 μM), a time point where no immediate cell death occurred at any of the doses. Results showed widespread effects on abundance of protein-coding genes for metabolism of reactive oxygen species, energy sensing, glycolysis, and protein homeostasis including the unfolded protein response and transcriptional regulation. Exposure to a concentration (10 μM Mn for 5 h) that did not result in cell death after 24-h increased abundance of differentially expressed genes (DEGs) in the protein secretion pathway that function in protein trafficking and cellular homeostasis. These include BET1 (Golgi vesicular membrane-trafficking protein), ADAM10 (ADAM metallopeptidase domain 10), and ARFGAP3 (ADP-ribosylation factor GTPase-activating protein 3). In contrast, 5-h exposure to 100 μM Mn, a concentration that caused cell death after 24 h, increased abundance of DEGs for components of the mitochondrial oxidative phosphorylation pathway. Integrated pathway analysis results showed that protein secretion gene set was associated with amino acid metabolites in response to 10 μM Mn, while oxidative phosphorylation gene set was associated with energy, lipid, and neurotransmitter metabolites at 100 μM Mn. These results show that differential effects of Mn occur at a concentration which does not cause subsequent cell death compared to a concentration that causes subsequent cell death. If these responses translate to effects on the secretory pathway and mitochondrial functions in vivo, differential activities of these systems could provide a sensitive basis to discriminate sub-toxic and toxic environmental and occupational Mn exposures.

Secretome analysis of nerve repair mediating Schwann cells reveals Smad-dependent trophism

Schwann cells promote nerve regeneration by adaptation of a regenerative phenotype referred to as repair mediating Schwann cell. Down-regulation of myelin proteins, myelin clearance, formation of Bungner's bands, and secretion of trophic factors characterize this cell type. We have previously shown that the sphingosine-1-phosphate receptor agonist Fingolimod/FTY720P promotes the generation of this particular Schwann cell phenotype by activation of dedifferentiation markers and concomitant release of trophic factors resulting in enhanced neurite growth of dorsal root ganglion neurons. Despite its biomedical relevance, a detailed characterization of the corresponding Schwann cell secretome is lacking, and the impact of FTY720P on enhancing neurite growth is not defined. Here, we applied a label-free quantitative mass spectrometry approach to characterize the secretomes derived from primary neonatal and adult rat Schwann cells in response to FTY720P. We identified a large proportion of secreted proteins with a high overlap between the neonatal and adult Schwann cells, which can be associated with biologic processes such as development, axon growth, and regeneration. Moreover, FTY720P-treated Schwann cells release proteins downstream of Smad signaling known to support neurite growth. Our results therefore uncover a network of trophic factors involved in glial-mediated repair of the peripheral nervous system.-Schira, J., Heinen, A., Poschmann, G., Ziegler, B., Hartung, H.-P., Stühler, K., Küry, P. Secretome analysis of nerve repair mediating Schwann cells reveals Smad-dependent trophism.

Regenerating CNS myelin: Emerging roles of regulatory T cells and CCN proteins

Efficient myelin regeneration in the central nervous system (CNS) requires the migration, proliferation and differentiation of oligodendrocyte progenitor cells (OPC) into myelinating oligodendrocytes. In demyelinating diseases such as multiple sclerosis (MS), this regenerative process can fail, and therapies targeting myelin repair are currently completely lacking in the clinic. The immune system is emerging as a key regenerative player in many tissues, such as muscle and heart. We recently reported that regulatory T cells (Treg) are required for efficient CNS remyelination. Furthermore, Treg secrete CCN3, a matricellular protein from the CCN family, implicated in regeneration of other tissues. Treg-derived CCN3 promoted oligodendrocyte differentiation and myelination. In contrast, previous studies showed that CCN2 inhibited myelination. These studies highlight the need for further scrutiny of the roles that CCN proteins play in myelin development and regeneration. Collectively, these findings open up exciting avenues of research to uncover the regenerative potential of the adaptive immune system.

Promoter-level expression clustering identifies time development of transcriptional regulatory cascades initiated by ErbB receptors in breast cancer cells

The analysis of CAGE (Cap Analysis of Gene Expression) time-course has been proposed by the FANTOM5 Consortium to extend the understanding of the sequence of events facilitating cell state transition at the level of promoter regulation. To identify the most prominent transcriptional regulations induced by growth factors in human breast cancer, we apply here the Complexity Invariant Dynamic Time Warping motif EnRichment (CIDER) analysis approach to the CAGE time-course datasets of MCF-7 cells stimulated by epidermal growth factor (EGF) or heregulin (HRG). We identify a multi-level cascade of regulations rooted by the Serum Response Factor (SRF) transcription factor, connecting the MAPK-mediated transduction of the HRG stimulus to the negative regulation of the MAPK pathway by the members of the DUSP family phosphatases. The finding confirms the known primary role of FOS and FOSL1, members of AP-1 family, in shaping gene expression in response to HRG induction. Moreover, we identify a new potential regulation of DUSP5 and RARA (known to antagonize the transcriptional regulation induced by the estrogen receptors) by the activity of the AP-1 complex, specific to HRG response. The results indicate that a divergence in AP-1 regulation determines cellular changes of breast cancer cells stimulated by ErbB receptors.

WITHDRAWN: Intrathecal siRNA against Cyr61 attenuates nociception in a rat model of inflammatory pain

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Inositol polyphosphate multikinase is a coactivator for serum response factor-dependent induction of immediate early genes

Inositol polyphosphate multikinase (IPMK) is a notably pleiotropic protein. It displays both inositol phosphate kinase and phosphatidylinositol kinase catalytic activities. Noncatalytically, IPMK stabilizes the mammalian target of rapamycin complex 1 and acts as a transcriptional coactivator for CREB-binding protein/E1A binding protein p300 and tumor suppressor protein p53. Serum response factor (SRF) is a major transcription factor for a wide range of immediate early genes. We report that IPMK, in a noncatalytic role, is a transcriptional coactivator for SRF mediating the transcription of immediate early genes. Stimulation by serum of many immediate early genes is greatly reduced by IPMK deletion. IPMK stimulates expression of these genes, an influence also displayed by catalytically inactive IPMK. IPMK acts by binding directly to SRF and thereby enhancing interactions of SRF with the serum response element of diverse genes.

Genetic modification of corneal neovascularization in Dstn (corn1) mice

Mutations in the gene for destrin (Dstn), an actin depolymerizing factor, lead to corneal abnormalities in mice. A null mutation in Dstn, termed Dstn (corn1) , isolated and maintained in the A.BY background (A.BY Dstn (corn1) ), results in corneal epithelial hyperproliferation, inflammation, and neovascularization. We previously reported that neovascularization in the cornea of Dstn (corn1) mice on the C57BL/6 background (B6.A.BY-Dstn (corn1) ) is significantly reduced when compared to A.BY Dstn (corn1) mice, suggesting the existence of genetic modifier(s). The purpose of this study is to identify the genetic basis of the difference in corneal neovascularization between A.BY Dstn (corn1) and B6.A.BY-Dstn (corn1) mice. We generated N2 mice for a whole-genome scan by backcrossing F1 progeny (A.BY Dstn (corn1) × B6.A.BY-Dstn (corn1) ) to B6.A.BY-Dstn (corn1) mice. N2 progeny were quantitatively phenotyped for the extent of corneal neovascularization and genotyped for markers across the mouse genome. We identified significant association of variability in corneal neovascularization with a locus on chromosome 3 (Chr3). The validity of the identified quantitative trait locus (QTL) was tested using B6 consomic mice carrying Chr3 from A/J mice. Dstn (corn1) mice from F1 and F2 intercrosses (B6.A.BY-Dstn (corn1)  × C57BL/6J-Chr3(A/J)/NaJ) were phenotyped for the extent of corneal neovascularization. This analysis showed that mice carrying the A/J allele at the QTL show significantly increased neovascularization. Our results indicate the existence of a modifier that genetically interacts with the Dstn gene. This modifier demonstrates allelic differences between C57BL6 and A.BY or A/J. The modifier is sufficient to increase neovascularization in Dstn (corn1) mice.

LY294002 and Rapamycin promote coxsackievirus-induced cytopathic effect and apoptosis via inhibition of PI3K/AKT/mTOR signaling pathway

Coxsackievirus B3 (CVB3) is a common human pathogen for acute myocarditis, pancreatitis, non-septic meningitis, and encephalitis; it induces a direct cytopathic effect (CPE) and apoptosis on infected cells. The Phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT/PKB)/mammalian target of Rapamycin (mTOR) signaling pathway regulates several cellular processes and it is one of the most important pathways in human networks. However, the effect and mechanism of PI3K/AKT/mTOR signaling pathway in CVB3 infected cells are poorly understood. In this study, we demonstrate that inhibition of PI3K/AKT/mTOR signaling pathway increased CVB3-induced CPE and apoptosis in HeLa cells. The activity of downstream targets of PI3K and mTOR is attenuated after CVB3 infection and inhibitors of PI3K and mTOR made their activity to decrease more significantly. We further show that LY294002 and Rapamycin, the inhibitor of PI3K and mTOR respectively, promote CVB3-induced CPE and apoptosis. Taken together, these data illustrate a new and imperative role for PI3K/AKT/mTOR signaling in CVB3 infection in HeLa cells and suggest an useful approach for the therapy of CVB3 infection.

Early phase of plasticity-related gene regulation and SRF dependent transcription in the hippocampus

Hippocampal organotypic cultures are a highly reliable in vitro model for studying neuroplasticity: in this paper, we analyze the early phase of the transcriptional response induced by a 20 µM gabazine treatment (GabT), a GABA-Ar antagonist, by using Affymetrix oligonucleotide microarray, RT-PCR based time-course and chromatin-immuno-precipitation. The transcriptome profiling revealed that the pool of genes up-regulated by GabT, besides being strongly related to the regulation of growth and synaptic transmission, is also endowed with neuro-protective and pro-survival properties. By using RT-PCR, we quantified a time-course of the transient expression for 33 of the highest up-regulated genes, with an average sampling rate of 10 minutes and covering the time interval [10∶90] minutes. The cluster analysis of the time-course disclosed the existence of three different dynamical patterns, one of which proved, in a statistical analysis based on results from previous works, to be significantly related with SRF-dependent regulation (p-value<0.05). The chromatin immunoprecipitation (chip) assay confirmed the rich presence of working CArG boxes in the genes belonging to the latter dynamical pattern and therefore validated the statistical analysis. Furthermore, an in silico analysis of the promoters revealed the presence of additional conserved CArG boxes upstream of the genes Nr4a1 and Rgs2. The chip assay confirmed a significant SRF signal in the Nr4a1 CArG box but not in the Rgs2 CArG box.

Cyr61, a matricellular protein, is needed for dendritic arborization of hippocampal neurons

The shape of the dendritic arbor is one of the criteria of neuron classification and reflects functional specialization of particular classes of neurons. The development of a proper dendritic branching pattern strongly relies on interactions between the extracellular environment and intracellular processes responsible for dendrite growth and stability. We previously showed that mammalian target of rapamycin (mTOR) kinase is crucial for this process. In this work, we performed a screen for modifiers of dendritic growth in hippocampal neurons, the expression of which is potentially regulated by mTOR. As a result, we identified Cyr61, an angiogenic factor with unknown neuronal function, as a novel regulator of dendritic growth, which controls dendritic growth in a β1-integrin-dependent manner.

Serum response factor modulates neuron survival during peripheral axon injury

Background

The transcription factor SRF (serum response factor) mediates neuronal survival in vitro. However, data available so far suggest that SRF is largely dispensable for neuron survival during physiological brain function.

Findings

Here, we demonstrate that upon neuronal injury, that is facial nerve transection, constitutively-active SRF-VP16 enhances motorneuron survival. SRF-VP16 suppressed active caspase 3 abundance in vitro and enhanced neuron survival upon camptothecin induced apoptosis. Following nerve fiber injury in vitro, SRF-VP16 improved survival of neurons and re-growth of severed neurites. Further, SRF-VP16 enhanced immune responses (that is microglia and T cell activation) associated with neuronal injury in vivo. Genome-wide transcriptomics identified target genes associated with axonal injury and modulated by SRF-VP16.

Conclusion

In sum, this is a first report describing a neuronal injury-related survival function for SRF.

Extracellular matrix protein CCN1 limits oncolytic efficacy in glioma

Oncolytic viral therapy has been explored widely as an option for glioma treatment but its effectiveness has remained limited. Cysteine rich 61 (CCN1) is an extracellular matrix (ECM) protein elevated in cancer cells that modulates their adhesion and migration by binding cell surface receptors. In this study, we examined a hypothesized role for CCN1 in limiting the efficacy of oncolytic viral therapy for glioma, based on evidence of CCN1 induction that occurs in this setting. Strikingly, we found that exogenous CCN1 in glioma ECM orchestrated a cellular antiviral response that reduced viral replication and limited cytolytic efficacy. Gene expression profiling and real-time PCR analysis revealed a significant induction of type-I interferon responsive genes in response to CCN1 exposure. This induction was accompanied by activation of the Jak/Stat signaling pathway, consistent with induction of an innate antiviral cellular response. Both effects were mediated by the binding of CCN1 to the cell surface integrin α6β1, activating its signaling and leading to rapid secretion of interferon-α, which was essential for the innate antiviral effect. Together, our findings reveal how an integrin signaling pathway mediates activation of a type-I antiviral interferon response that can limit the efficacy of oncolytic viral therapy. Furthermore, they suggest therapeutic interventions to inhibit CCN1-integrin α6 interactions to sensitize gliomas to viral oncolysis.

G(alpha)12/13 induction of CYR61 in association with arteriosclerotic intimal hyperplasia: effect of sphingosine-1-phosphate

OBJECTIVE

Gα(12/13) play a role in oncogenic transformation and tumor growth. Cysteine-rich protein 61 (CYR61) is a growth-factor-inducible angiogenic factor. In view of potential overlapping functions between Gα(12/13) and CYR61, this study investigated the role of these G proteins in CYR61 induction in association with hyperplastic vascular abnormality.

METHODS AND RESULTS

Overexpression of activated Gα(12) or Gα(13) induced CYR61 expression in vascular smooth muscle cells (VSMCs). Gene knockdown and knockout experiments revealed that sphingosine-1-phosphate (S1P) treatment induced CYR61 via Gα(12/13). JunD/activator protein-1 (AP-1) was identified as a transcription factor required for CYR61 transactivation by S1P. Deficiencies in Gα(12/13) abrogated AP-1 activation and AP-1-mediated CYR61 induction. c-Jun N-terminal kinase was responsible for CYR61 induction. Moreover, deficiencies of Gα(12/13) abolished c-Jun N-terminal kinase-dependent CYR61 induction by S1P. N-acetyl-l-cysteine or NADPH oxidase inhibitor treatment reversed CYR61 induction by S1P, indicating that reactive oxygen species are responsible for this process. The levels of Gα(12/13) were increased within thickened intimas and medias in wire-injured mouse femoral arteries, which was accompanied by simultaneous CYR61 induction. Moreover, Gα(12/13) and CYR61 were costained in the arteriosclerotic lesions immediately adjacent to human tumor tissues.

CONCLUSIONS

Gα(12/13) regulate AP-1-dependent CYR61 induction in VSMCs and promote VSMC migration, and they are upregulated with CYR61 in arteriosclerotic lesions.

Increased mitochondrial calcium sensitivity and abnormal expression of innate immunity genes precede dopaminergic defects in Pink1-deficient mice

Background

PTEN-induced kinase 1 (PINK1) is linked to recessive Parkinsonism (EOPD). Pink1 deletion results in impaired dopamine (DA) release and decreased mitochondrial respiration in the striatum of mice. To reveal additional mechanisms of Pink1-related dopaminergic dysfunction, we studied Ca²⁺ vulnerability of purified brain mitochondria, DA levels and metabolism and whether signaling pathways implicated in Parkinson's disease (PD) display altered activity in the nigrostriatal system of Pink1^−/− mice.

Methods and Findings

Purified brain mitochondria of Pink1^−/− mice showed impaired Ca²⁺ storage capacity, resulting in increased Ca²⁺ induced mitochondrial permeability transition (mPT) that was rescued by cyclosporine A. A subpopulation of neurons in the substantia nigra of Pink1^−/− mice accumulated phospho-c-Jun, showing that Jun N-terminal kinase (JNK) activity is increased. Pink1^−/− mice 6 months and older displayed reduced DA levels associated with increased DA turnover. Moreover, Pink1^−/− mice had increased levels of IL-1β, IL-12 and IL-10 in the striatum after peripheral challenge with lipopolysaccharide (LPS), and Pink1^−/− embryonic fibroblasts showed decreased basal and inflammatory cytokine-induced nuclear factor kappa-β (NF-κB) activity. Quantitative transcriptional profiling in the striatum revealed that Pink1^−/− mice differentially express genes that (i) are upregulated in animals with experimentally induced dopaminergic lesions, (ii) regulate innate immune responses and/or apoptosis and (iii) promote axonal regeneration and sprouting.

Conclusions

Increased mitochondrial Ca²⁺ sensitivity and JNK activity are early defects in Pink1^−/− mice that precede reduced DA levels and abnormal DA homeostasis and may contribute to neuronal dysfunction in familial PD. Differential gene expression in the nigrostriatal system of Pink1^−/− mice supports early dopaminergic dysfunction and shows that Pink1 deletion causes aberrant expression of genes that regulate innate immune responses. While some differentially expressed genes may mitigate neurodegeneration, increased LPS-induced brain cytokine expression and impaired cytokine-induced NF-κB activation may predispose neurons of Pink1^−/− mice to inflammation and injury-induced cell death.

Mechanical regulation of the proangiogenic factor CCN1/CYR61 gene requires the combined activities of MRTF-A and CREB-binding protein histone acetyltransferase

Smooth muscle-rich tissues respond to mechanical overload by an adaptive hypertrophic growth combined with activation of angiogenesis, which potentiates their mechanical overload-bearing capabilities. Neovascularization is associated with mechanical strain-dependent induction of angiogenic factors such as CCN1, an immediate-early gene-encoded matricellular molecule critical for vascular development and repair. Here we have demonstrated that mechanical strain-dependent induction of the CCN1 gene involves signaling cascades through RhoA-mediated actin remodeling and the p38 stress-activated protein kinase (SAPK). Actin signaling controls serum response factor (SRF) activity via SRF interaction with the myocardin-related transcriptional activator (MRTF)-A and tethering to a single CArG box sequence within the CCN1 promoter. Such activity was abolished in mechanically stimulated mouse MRTF-A(-/-) cells or upon inhibition of CREB-binding protein (CBP) histone acetyltransferase (HAT) either pharmacologically or by siRNAs. Mechanical strain induced CBP-mediated acetylation of histones 3 and 4 at the SRF-binding site and within the CCN1 gene coding region. Inhibition of p38 SAPK reduced CBP HAT activity and its recruitment to the SRF.MRTF-A complex, whereas enforced induction of p38 by upstream activators (e.g. MKK3 and MKK6) enhanced both CBP HAT and CCN1 promoter activities. Similarly, mechanical overload-induced CCN1 gene expression in vivo was associated with nuclear localization of MRTF-A and enrichment of the CCN1 promoter with both MRTF-A and acetylated histone H3. Taken together, these data suggest that signal-controlled activation of SRF, MRTF-A, and CBP provides a novel connection between mechanical stimuli and angiogenic gene expression.

Effects of schizophrenomimetics on the expression of the CCN1 (CYR 61) gene encoding a matricellular protein in the infant and adult neocortex of the mouse and rat

The acute systemic administration of a schizophrenomimetic phencyclidine [5 or 10 mg/kg, subcutaneously (s.c.)] markedly up-regulated the neocortical expression of the CCN1 gene encoding a secreted extracellular matrix-associated protein at postnatal day 56, but not at postnatal day 8, after 60 min in the mouse and rat. The development-dependent nature of the up-regulation between postnatal days 8 and 56 seems to be similar to that of the adult type phencyclidine-induced abnormal behaviours, which have been considered to be models of schizophrenic symptoms. In the young adult rat, 5, 10, and 20 mg/kg phencyclidine (given s.c.) induced an increase in the CCN1 gene transcripts in a dose-related and bell-shaped manner with a maximum at the dose of 10 mg/kg, 60 min post-injection. Other schizophrenomimetics, dizocilpine (1 mg/kg) and methamphetamine (4.8 mg/kg), also caused a prominent up-regulation of the neocortical expression of the CCN1 gene in adult rats. These results indicate that the CCN1 gene or protein could be implicated in a molecular cascade associated with the age-dependent onset of schizophrenia that usually occurs after puberty.

GRASP-1 is a neuronal scaffold protein for the JNK signaling pathway

GRASP-1 is a neuronally enriched protein that interacts with the AMPA-type glutamate receptor/GRIP complex. GRASP-1 can be cleaved by Caspase-3 in both normal and ischemic brains although the functional significance of this cleavage remains elusive. We investigated signal transduction pathways that might lie downstream of GRASP-1 and found that GRASP-1 potently activates JNK pathway signaling, with no effect on ERK signaling. Such JNK pathway activating activity requires binding of GRASP-1 to both JNK and the upstream JNK pathway activator MEKK-1. Furthermore, mutations that prevent Caspase 3-cleavage of GRASP-1 dramatically inhibit the JNK pathway activating activity of GRASP-1, suggesting a novel link between Caspase-3 activation and JNK pathway signaling. These results suggest that GRASP-1 serves as a scaffold protein to facilitate MEKK-1 activation of JNK signaling in neurons.

Expression changes in mouse brains following nicotine-induced seizures: the modulation of transcription factor networks

Nicotine, acting through the neuronal nicotinic acetylcholine receptors (nAChRs), can induce seizures in mice. We aimed to study brain transcriptional response to seizure and to identify genes whose expression is altered after nicotine-induced seizures. Whole brains of untreated mice were compared with brains 1 h after seizure activity, using Affymetrix U74Av2 microarrays. Experimental groups included wild-type mice and both nicotine-induced seizure-sensitive and -resistant nAChR mutant mice. Each genotype group received different nicotine doses to generate seizures. This approach allowed the identification of significantly changed genes whose expression was dependent on seizure activity, nicotine administration, or both but not on the type of nAChR subunit mutation or the amount of nicotine injected. Significant expression changes were detected in 62 genes ( P < 0.05, false discovery rate correction). Among them, gene ontology functional annotation analysis determined that the most significantly overrepresented categories were of genes encoding MAP kinase phosphatases, regulators of transcription and nucleosome assembly proteins. In silico bioinformatic analysis of the promoter regions of the 62 changed genes detected significant enrichments of 16 transcription regulatory elements (TREs), creating a network of transcriptional regulatory responses to seizures. The TREs for activating transcription factor and serum response factor were most significantly enriched, supporting their association with seizure activity. Our data suggest that nicotine-induced seizure in mice is a useful model to study seizure activity and its global brain transcriptional response. The differentially expressed genes detected here can help us to understand the molecular mechanisms underlying seizures in animal models and may also serve as candidate genes to study epilepsy in humans.

CCN1 protects cardiac myocytes from oxidative stress via β1 integrin–Akt pathway

CCN1 (Cyr61) is a secreted matricellular protein, mediating angiogenesis and cell survival through interaction with integrins. Although CCN1 expression is induced in the heart during ischemia and pressure overload, its function in cardiac myocytes remains to be elucidated. We hypothesized that CCN1 may not only induce angiogenesis but may also have a direct effect on cardiac myocytes during ischemia. In this study, we investigated the effect of CCN1 on survival of cardiac myocytes under oxidative stress and examined a signal transduction pathway downstream of CCN1. A solid-phase binding assay demonstrated that CCN1 was bound to cardiac myocytes in a dose-dependent, saturable manner. Inactivation of beta1 integrin in cardiac myocytes inhibited binding with CCN1, indicating that CCN1 was bound to cardiac myocytes via beta1 integrin. Knockdown of endogenous CCN1 decreased the number of surviving cells under oxidative stress, while pretreatment of cardiac myocytes with recombinant CCN1 significantly increased the number of surviving cells. Moreover, TUNEL staining showed that CCN1 significantly decreased apoptotic cells. Furthermore, treatment of cardiac myocytes with CCN1 induced phosphorylation of Akt and extracellular signal-regulated kinase (ERK). Inactivation of beta1 integrin inhibited CCN1-induced phosphorylation of these kinases and abolished the protective effect of CCN1. Moreover, pretreatment of cells with wortmannin completely blocked the protective effect of CCN1 on cardiac myocytes under oxidative stress, indicating that the protective effect of CCN1 was mainly mediated by activation of Akt. The antiapoptotic effect of CCN1 on cardiac myocytes together with its proangiogenic property could be beneficial in the treatment of ischemic heart disease.

Forkhead transcription factor FOXO3a is a negative regulator of angiogenic immediate early gene CYR61, leading to inhibition of vascular smooth muscle cell proliferation and neointimal hyperplasia

Cysteine-rich angiogenic protein 61 (CYR61, CCN1) is an immediate early gene expressed in vascular smooth muscle cells (VSMCs) on growth factor stimulation, and its expression has been suggested to be associated with postangioplasty restenosis. The forkhead transcription factors are reported to play various roles in cellular proliferation, apoptosis, and even adaptation to cellular stress. We hypothesized that the forkhead transcription factor FOXO3a may regulate CYR61 expression in VSMCs and investigated the CYR61-modulating effect of FOXO3a in the process of vascular response to vasoactive signals and vascular injury. To evaluate the effect of FOXO3a on CYR61 expression, rat VSMCs were infected with adenoviral vectors expressing constitutively active FOXO3a (Ad-TM-FOXO3a). Constitutively active FOXO3a gene transduction suppressed CYR61 expression. Luciferase assay with the deletion constructs of the forkhead factor binding motif in CYR61 promoter region, which resulted in a significant decrease in luciferase expression compared with the intact construct, and chromatin immunoprecipitation analysis confirmed transcriptional regulation of CYR61 by FOXO3a. Serum and angiotensin II rapidly induced CYR61 expression, which was significantly reduced by Ad-TM-FOXO3a. Reduction of VSMC proliferation and migration associated with FOXO3a activation was significantly reversed by cotransfection of adenoviral vector expressing CYR61, whereas apoptosis induction by FOXO3a was not influenced. In a rat balloon carotid arterial injury model, CYR61 was rapidly induced in VSMCs in the early stage of injury and remained elevated until 14 days, which was suppressed by Ad-TM-FOXO3a transfection. After 14 days, there was a significant reduction in neointima by FOXO3a transduction compared with the control group (0.06+/-0.02 versus 0.20+/-0.07 mm(2), P<0.01). Such reduction of neointimal hyperplasia by Ad-TM-FOXO3a was reversed by CYR61 replenishment. These data suggest that FOXO3a is a negative transcription factor of CYR61 and that suppression of CYR61 is among several mechanisms by which FOXO3a inhibits VSMC proliferation and neointimal hyperplasia.

Genomic expression profiling of human inflammatory cardiomyopathy (DCMi) suggests novel therapeutic targets

The clinical phenotype of human dilated cardiomyopathy (DCM) encompasses a broad spectrum of etiologically distinct disorders. As targeting of etiology-related pathogenic pathways may be more efficient than current standard heart failure treatment, we obtained the genomic expression profile of a DCM subtype characterized by cardiac inflammation to identify possible new therapeutic targets in humans. In this inflammatory cardiomyopathy (DCMi), a distinctive cardiac expression pattern not described in any previous study of cardiac disorders was observed. Two significantly altered gene networks of particular interest and possible interdependence centered around the cysteine-rich angiogenic inducer 61 (CYR61) and adiponectin (APN) gene. CYR61 overexpression, as in human DCMi hearts in situ, was similarly induced by inflammatory cytokines in vascular endothelial cells in vitro. APN was strongly downregulated in DCMi hearts and completely abolished cytokine-dependent CYR61 induction in vitro. Dysbalance between the CYR61 and APN networks may play a pathogenic role in DCMi and contain novel therapeutic targets. Multiple immune cell-associated genes were also deregulated (e.g., chemokine ligand 14, interleukin-17D, nuclear factors of activated T cells). In contrast to previous investigations in patients with advanced or end-stage DCM where etiology-related pathomechanisms are overwhelmed by unspecific processes, the deregulations detected in this study occurred at a far less severe and most probably fully reversible disease stage.

The matrix protein CCN1 (CYR61) induces apoptosis in fibroblasts

Integrin-mediated cell adhesion to extracellular matrix proteins is known to promote cell survival, whereas detachment from the matrix can cause rapid apoptotic death in some cell types. Contrary to this paradigm, we show that fibroblast adhesion to the angiogenic matrix protein CCN1 (CYR61) induces apoptosis, whereas endothelial cell adhesion to CCN1 promotes cell survival. CCN1 induces fibroblast apoptosis through its adhesion receptors, integrin α₆β₁ and the heparan sulfate proteoglycan (HSPG) syndecan-4, triggering the transcription-independent p53 activation of Bax to render cytochrome c release and activation of caspase-9 and -3. Neither caspase-8 activity nor de novo transcription or translation is required for this process. These results show that cellular interaction with a specific matrix protein can either induce or suppress apoptosis in a cell type–specific manner and that integrin α₆β₁-HSPGs can function as receptors to induce p53-dependent apoptosis.

Structural and functional properties of CCN proteins

The CCN family currently comprises six members (CCN1-6) that regulate diverse cell functions, including mitogenesis, adhesion, apoptosis, extracellular matrix (ECM) production, growth arrest, and migration. These properties can result in a multiplicity of effects during development, differentiation, wound healing, and disease states, such as tumorigenesis and fibrosis. CCN proteins have emerged as major regulators of chondrogenesis, angiogenesis, and fibrogenesis. CCN proteins are mosaic in nature and consist of up to four structurally conserved modules, at least two of which are involved in binding to cell surfaces via molecules that include integrins, heparan sulfate proteoglycans, and low-density lipoprotein receptor-related protein. CCN proteins use integrins as signal transducing receptors to regulate context-dependent responses in individual cell types. The involvement of integrins in mediating CCN signaling allows for considerable plasticity in response because some effects are specific for certain integrin subtypes and integrin signaling is coordinated with other signaling pathways in the cell. In addition to their own biological properties, CCN proteins regulate the functions of other bioactive molecules (e.g., growth factors) via direct binding interactions. CCN molecules demonstrate complex multifaceted modes of action and regulation and have emerged as important matricellular regulators of cell function.

Coxsackievirus B3 infection induces cyr61 activation via JNK to mediate cell death

Coxsackievirus B3 (CVB3), an enterovirus in the Picornavirus family, is the most common human pathogen associated with myocarditis and idiopathic dilated cardiomyopathy. We found upregulation of the cysteine-rich protein gene (cyr61) after CVB3 infection in HeLa cells with a cDNA microarray approach, which is confirmed by Northern blot analysis. It is also revealed that the extracellular amount of Cyr61 protein was increased after CVB3 infection in HeLa cells. cyr61 is an early-transcribed gene, and the Cyr61 protein is secreted into the extracellular matrix. Its function is related to cell adhesion, migration, and neuronal cell death. Here, we show that activation of the cyr61 promoter by CVB3 infection is dependent on JNK activation induced by CVB3 replication and viral protein expression in infected cells. To explore the role of Cyr61 protein in infected HeLa cells, we transiently overexpressed cyr61 and infected HeLa cells with CVB3. This increased CVB3 growth in the cells and promoted host cell death by viral infection, whereas down-expression of cyr61 with short interfering RNA reduced CVB3 growth and showed resistance to cell death by CVB3 infection. In conclusion, we have demonstrated a new role for cyr61 in HeLa cells infected with CVB3, which is associated with the cell death induced by virus infection. These data thus expand our understanding of the physiological functions of cyr61 in virus-induced cell death and provide new insights into the cellular factors involved.

Cyr61 suppresses growth of human endometrial cancer cells

Cyr61 (CCN1) is a member of the CCN protein family; these secreted proteins are involved in diverse biological processes such as cell adhesion, angiogenesis, apoptosis, and either growth arrest or growth stimulation depending on the cellular context. We studied the role of Cyr61 in endometrial tumorigenesis. Levels of Cyr61 were decreased in endometrial tumors compared with normal endometrium. Knockdown of Cyr61 expression by RNA interference in a well differentiated endometrial adenocarcinoma cell line (Ishikawa) stimulated its cellular growth. Conversely, overexpression of the protein in the undifferentiated AN3CA endometrial cancer cell line decreased their growth concurrently with increased apoptosis in liquid culture. These same cells had decreased clonogenic capacity and a nearly complete loss of tumorigenicity in vivo. Furthermore, partially purified Cyr61 suppressed growth of endometrial cancer cells. The increased apoptosis in these endometrial cancer cells with forced overexpression of Cyr61 was associated with elevated expression of the pro-apoptotic proteins Bax, Bad, and TRAIL (tumor necrosis factor receptor-associated ligand). Cyr61-induced caspase-3 activation and depolarization of mitochondrial membrane. In summary, endometrial cancer cells have decreased expression of Cyr61 compared with normal endometrium, and this lowered expression may provide the transformed cells a growth advantage over their normal counterpart.

Fingerprinting the diseased prostate: associations between BPH and prostate cancer

Two of the most common diseases which occur in ageing men relate to their prostate. BPH and prostate cancer are prevalent diseases which have an impact on most men as they age. The advent of gene expression analysis has provided an opportunity to examine these diseases in a novel fashion. These analyses, to date, have revealed associations between these two diseases which have not been previously identified. These commonalities include global genetic changes which occur throughout the prostates in individuals with these diseases. Understanding the fingerprints of these diseases is providing novel markers and treatment strategies for both BPH and prostate cancer.

Regulation of Cyr61/CCN1 gene expression through RhoA GTPase and p38MAPK signaling pathways

Cysteine-rich protein 61 (Cyr61/CCN1) is an angiogenic factor and a member of a family of growth factor-inducible immediate-early genes with functions in cell adhesion, proliferation and differentiation. We investigated the regulatory mechanisms and signaling pathways involved in Cyr61/CCN1gene activation in smooth muscle cells. Treatment of these cells with sphingosine 1-phosphate (S1P), a bioactive lysolipid, increased rapidly but transiently the expression of the Cyr61/CCN1 gene at both the mRNA and protein levels. Cyr61/CCN1 mRNA stability was not altered but the transcription rate of the Cyr61/CCN1 gene was increased fivefold in isolated nuclei from S1P-stimulated cells indicating that the level of control is primarily transcriptional. Transfection experiments showed that a 936-bp promoter fragment of the human Cyr61/CCN1 gene is functional and induces a reporter gene activity in S1P-treated cells. Using a combination of cis-element mutagenesis and expression of dominant negative inhibitors of transcription factors, we showed that both a CRE and AP-1 site and their cognate transcription factors, cAMP response element binding protein (CREB) and AP-1, were responsible for the promoter activity in S1P-stimulated cells. Furthermore, by using either pharmacological inhibitors or active forms of known signaling molecules, we showed that inducible Cyr61/CCN1 gene expression occurs through RhoA GTPase and that additional signaling through the p38 pathway is required. In particular, p38 seems to regulate Cyr61/CCN1 promoter activity through modulation of phosphorylation of CREB and the CREB kinase, MSK1. These findings demonstrate the transcriptional regulation of the Cyr61/CCN1 gene and provide clues to the signaling molecules and transcription factors involved in such regulation.