Characterization of the human p11 promoter sequence

Sp1-regulated expression of p11 contributes to motor neuron degeneration by membrane insertion of TASK1

Disruption in membrane excitability contributes to malfunction and differential vulnerability of specific neuronal subpopulations in a number of neurological diseases. The adaptor protein p11, and background potassium channel TASK1, have overlapping distributions in the CNS. Here, we report that the transcription factor Sp1 controls p11 expression, which impacts on excitability by hampering functional expression of TASK1. In the SOD1-G93A mouse model of ALS, Sp1-p11-TASK1 dysregulation contributes to increased excitability and vulnerability of motor neurons. Interference with either Sp1 or p11 is neuroprotective, delaying neuron loss and prolonging lifespan in this model. Nitrosative stress, a potential factor in human neurodegeneration, stimulated Sp1 expression and human p11 promoter activity, at least in part, through a Sp1-binding site. Disruption of Sp1 or p11 also has neuroprotective effects in a traumatic model of motor neuron degeneration. Together our work suggests the Sp1-p11-TASK1 pathway is a potential target for treatment of degeneration of motor neurons.

The adaptor protein p11 and K+ channel TASK1 have overlapping distributions in the CNS. Here, the authors demonstrate that the transcription factor Sp1 regulates p11 levels, which in turn affects intrinsic membrane properties and can contribute to degeneration of motor neurons in disease and injury models.

The involvement of phospholipases A2 in asthma and chronic obstructive pulmonary disease

The increased morbidity, mortality, and ineffective treatment associated with the pathogenesis of chronic inflammatory diseases such as asthma and chronic obstructive pulmonary disease (COPD) have generated much research interest. The key role is played by phospholipases from the A2 superfamily: enzymes which are involved in inflammation through participation in pro- and anti-inflammatory mediators production and have an impact on many immunocompetent cells. The 30 members of the A2 superfamily are divided into 7 groups. Their role in asthma and COPD has been studied in vitro and in vivo (animal models, cell cultures, and patients). This paper contains complete and updated information about the involvement of particular enzymes in the etiology and course of asthma and COPD.

S100 proteins as diagnostic and prognostic markers in colorectal and hepatocellular carcinoma

CONTEXT

Clinical and experimental studies have suggested a link between S100 gene ex-pression and neoplastic disorders, however, the molecular mechanisms of this associa-tion are not well understood. The aim of this review was to conduct a comprehensive literature search in order to understand the possible underlying molecular mechanisms of this association. We also discuss their application as diagnostic and prognostic mark-ers in colorectal and hepatocellular carcinoma.

EVIDENCE ACQUISITIONS

We searched Pubmed (NLM) and Web of Science (ISI Web of Knowledge).

RESULTS

S100 genes display a complex expression pattern in colorectal and hepatocel- lular carcinoma. They are expressed in tumor and/or tumor stroma cells, and they exert both pro- and antitumorigenic actions. In view of this complexity, it becomes clear that S100 proteins might act as both friend and foe. The biological role of the S100 genes is predicted to depend on the relative contributions of the different cell types at specific stages of tumor progression.

CONCLUSIONS

Further research is required in order to uncover the functional role of S100 genes in tumorigenesis. Answers to this issue are needed before we can more fully un-derstand the clinical relevance of S100 protein expression within epithelial tumors, with regard to their potential applicability as biomarkers for diagnosis and therapy decisions.

Double suicide genes selectively kill human umbilical vein endothelial cells

Background

To construct a recombinant adenovirus containing CDglyTK double suicide genes and evaluate the killing effect of the double suicide genes driven by kinase domain insert containing receptor (KDR) promoter on human umbilical vein endothelial cells.

Methods

Human KDR promoter, Escherichia coli (E. coli) cytosine deaminase (CD) gene and the herpes simplex virus-thymidine kinase (TK) gene were cloned using polymerase chain reaction (PCR). Plasmid pKDR-CDglyTK was constructed with the KDR promoter and CDglyTK genes. A recombinant adenoviral plasmid AdKDR-CDglyTK was then constructed and transfected into 293 packaging cells to grow and harvest adenoviruses. KDR-expressing human umbilical vein endothelial cells (ECV304) and KDR-negative liver cancer cell line (HepG2) were infected with the recombinant adenoviruses at different multiplicity of infection (MOI). The infection rate was measured by green fluorescent protein (GFP) expression. The infected cells were cultured in culture media containing different concentrations of prodrugs ganciclovir (GCV) and/or 5-fluorocytosine (5-FC). The killing effects were measured using two different methods, i.e. annexin V-FITC staining and terminal transferase-mediated dUTP nick end-labeling (TUNEL) staining.

Results

Recombinant adenoviruses AdKDR-CDglyTK were successfully constructed and they infected ECV304 and HepG2 cells efficiently. The infection rate was dependent on MOI of recombinant adenoviruses. ECV304 cells infected with AdKDR-CDglyTK were highly sensitive to GCV and 5-FC. The cell survival rate was dependent on both the concentration of the prodrugs and the MOI of recombinant adenoviruses. In contrast, there were no killing effects in the HepG2 cells. The combination of two prodrugs was much more effective in killing ECV304 cells than GCV or 5-FC alone. The growth of transgenic ECV304 cells was suppressed in the presence of prodrugs.

Conclusion

AdKDR-CDglyTK/double prodrog system may be a useful method for suppressing tumor angiogenesis.

A role for p11 in the antidepressant action of brain-derived neurotrophic factor

BACKGROUND

The protein p11 (also called S100A10) is downregulated in human and rodent depressive-like states. Considerable experimental evidence also implicates p11 in the mechanism of action of antidepressant drugs and electroconvulsive seizures, in part due to its interaction with specific serotonin receptors. Brain-derived neurotrophic factor (BDNF) has been linked to the therapeutic activity of antidepressants in rodent models and humans. In the current study, we investigated whether BDNF regulates p11 in vitro and in vivo.

METHODS

We utilized primary neuronal cultures, in vivo analyses of transgenic mice, and behavioral techniques to assess the effects of BDNF on p11.

RESULTS

Results indicate that BDNF stimulates p11 expression through tropomyosin-related kinase B (trkB) receptors and via the mitogen-activated protein kinase signaling pathway. Brain-derived neurotrophic factor-induced changes in p11 in vivo correlate with changes in ligand binding to the 5-hydroxytryptamine receptor 1B, the subcellular localization of which is known to be regulated by p11. Behavioral studies demonstrate that p11 knockout mice are insensitive to the antidepressant actions of BDNF.

CONCLUSIONS

Taken together, our data demonstrate that p11 levels are regulated by BDNF in vitro and in vivo and that the antidepressant-like effect of BDNF in two well-established behavioral models requires p11. These data support a role for p11 in the antidepressant activity of neurotrophins.

Stress at the synapse: signal transduction mechanisms of adrenal steroids at neuronal membranes

As the key neuron-to-neuron interface, the synapse is involved in learning and memory, including traumatic memories during times of stress. However, the signal transduction mechanisms by which stress mediates its lasting effects on synapse transmission and on memory are not fully understood. A key component of the stress response is the increased secretion of adrenal steroids. Adrenal steroids (e.g., cortisol) bind to genomic mineralocorticoid and glucocorticoid receptors (gMRs and gGRs) in the cytosol. In addition, they may act through membrane receptors (mMRs and mGRs), and signal transduction through these receptors may allow for rapid modulation of synaptic transmission as well as modulation of membrane ion currents. mMRs increase synaptic and neuronal excitability; mechanisms include the facilitation of glutamate release through extracellular signal-regulated kinase signal transduction. In contrast, mGRs decrease synaptic and neuronal excitability by reducing calcium currents through N-methyl-D-aspartate receptors and voltage-gated calcium channels by way of protein kinase A- and G protein-dependent mechanisms. This body of functional data complements anatomical evidence localizing GRs to the postsynaptic membrane. Finally, accumulating data also suggest the possibility that mMRs and mGRs may show an inverted U-shaped dose response, whereby glutamatergic synaptic transmission is increased by low doses of corticosterone acting at mMRs and decreased by higher doses acting at mGRs. Thus, synaptic transmission is regulated by mMRs and mGRs, and part of the stress signaling response is a direct and bidirectional modulation of the synapse itself by adrenal steroids.

p11 is up-regulated in the forebrain of stressed rats by glucocorticoid acting via two specific glucocorticoid response elements in the p11 promoter

Posttraumatic stress disorder (PTSD) is one of the most common psychiatric disorders. Despite the extensive study of the neurobiological correlates of this disorder, the underlying mechanisms of PTSD are still poorly understood. Recently, a study demonstrated that dexamethasone (Dex), a synthetic glucocorticoid, can up-regulate p11, known as S100A10-protein which is down-regulated in patients with depression, (Yao et al., 1999; Huang et al., 2003) a common comorbid disorder in PTSD. These observations led to our hypothesis that traumatic stress may alter expression of p11 mediated through a glucocorticoid receptor. Here, we demonstrate that inescapable tail shock increased both prefrontal cortical p11 mRNA levels and plasma corticosterone levels in rats. We also found that Dex up-regulated p11 expression in SH-SY5Y cells through glucocorticoid response elements (GREs) within the p11 promoter. This response was attenuated by either RU486, a glucocorticoid receptor (GR) antagonist or mutating two of three glucocorticoid response elements (GRE2 and GRE3) in the p11 promoter. Finally, we showed that p11 mRNA levels were increased in postmortem prefrontal cortical tissue (area 46) of patients with PTSD. The data obtained from our work in a rat model of inescapable tail shock, a p11-transfected cell line and postmortem brain tissue from PTSD patients outline a possible mechanism by which p11 is regulated by glucocorticoids elevated by traumatic stress.

Investigating the role of p11 (S100A10) sequence variation in susceptibility to major depression

Recent evidence suggests a potential role for the p11 gene in conferring risk to depressive disorders. p11 has been shown to influence serotonergic transmission, and its expression was found to be reduced in a mouse model of depression, as well as in post-mortem brain tissue from major depressive disorder (MDD) cases. In the present study, we tested for rare variants in p11 by resequencing promoter, exonic and flanking intronic regions in 176 MDD cases and 176 matched controls. We also assessed common variation by genotyping eight single nucleotide polymorphisms (SNPs), seven tag SNPs and one found through resequencing, in 641 cases and 650 controls. Resequencing revealed nine novel rare variants, including a missense mutation (Asp60Glu) observed in one case and one control, and four variants that occurred only in cases and not controls. The number of rare variants in cases did not exceed that expected by chance for the length of sequence analyzed, and also was not significantly greater than that observed in controls. Resequencing also identified two known SNPs, one (rs4845720) of which was significantly more frequent in cases than controls in the resequenced sample (3.1% vs. 0.9%, P = 0.03), though not in the larger sample (3% vs. 2%, P = 0.15). None of the tag SNPs showed any evidence of association. Our results do not support a major role for either common or rare p11 SNPs with MDD. Several limitations of the study are discussed.

Epigenetic deregulation of multiple S100 gene family members by differential hypomethylation and hypermethylation events in medulloblastoma

Deregulated expression of genes encoding members of the S100 family of calcium-binding proteins has been associated with the malignant progression of multiple tumour types. Using a pharmacological expression reactivation approach, we screened 16 S100 genes for evidence of epigenetic regulation in medulloblastoma, the most common malignant brain tumour of childhood. Four family members (S100A2, S100A4, S100A6 and S100A10) demonstrated evidence of upregulated expression in multiple medulloblastoma cell lines, following treatment with the DNA methyltransferase inhibitor, 5′-aza-2′-deoxycytidine. Subsequent analysis revealed methylation of critical CpG sites located within these four genes in an extended cell line panel. Assessment of these genes in the non-neoplastic cerebellum (from which medulloblastomas develop) revealed strong somatic methylation affecting S100A2 and S100A4, whereas S100A6 and S100A10 were unmethylated. Assessed against these normal tissue-specific methylation states, S100A6 and S100A10 demonstrated tumour-specific hypermethylation in medulloblastoma primary tumours (5 out of 40 and 4 out of 35, respectively, both 12%) and cell lines (both 7 out of 9, 78%), which was associated with their transcriptional silencing. Moreover, S100A6 hypermethylation was significantly associated with the aggressive large cell/anaplastic morphophenotype (P=0.026). In contrast, pro-metastatic S100A4 displayed evidence of hypomethylation relative to the normal cerebellum in a significant proportion primary tumours (7 out of 41, 17%) and cell lines (3 out of 9, 33%), which was associated with its elevated expression. In summary, these data characterise complex patterns of somatic methylation affecting S100 genes in the normal cerebellum and demonstrate their disruption causing epigenetic deregulation of multiple S100 family members in medulloblastoma development. Epigenetic events affecting S100 genes have potential clinical utility and merit further investigation as molecular biomarkers for this disease.

Functional characterization of the promoter of the human glucose transporter 10 gene

The human SLC2A10 gene encodes the high-affinity glucose transporter 10 (GLUT10) and is widely expressed in adult tissues, including organs which play major roles in glucose homeostasis. Its function and genomic location in a region linked to Type 2 diabetes susceptibility are consistent with a potential role in Type 2 diabetes. Analysis of the CpG-rich promoter revealed the presence of two major transcription start points with differential use in tissues and cell lines. Mapping of transcriptionally active regions in the 5' flanking sequence identified a region, located between nucleotides -70 and -14 (relative to the major transcription start point) as the SLC2A10 basal promoter. This sequence harbors consensus binding sites for Sp, AP2alpha, and other transcription factors. A juxtaposed Sp/AP2alpha motif located between -25 and -11 is critical for core promoter function. In cells expressing Sp and AP2 factors, the two motifs are required for maximal activation of the basal promoter. In cells lacking AP2alpha, transcription is dependent on the integrity of the Sp site. Using electrophoresis mobility shift assays, we demonstrate that Sp1 and Sp3 bind to the GC-box in site 5 forming specific complexes. In addition, a silencer region is present upstream of -696 which down-regulates SLC2A10 promoter activity independently of its distance to the transcript start site.