Differential cooperation between regulatory sequences required for human CD53 gene expression

Oncogenic Sox2 regulates and cooperates with VRK1 in cell cycle progression and differentiation

Sox2 is a pluripotency transcription factor that as an oncogene can also regulate cell proliferation. Therefore, genes implicated in several different aspects of cell proliferation, such as the VRK1 chromatin-kinase, are candidates to be targets of Sox2. Sox 2 and VRK1 colocalize in nuclei of proliferating cells forming a stable complex. Sox2 knockdown abrogates VRK1 gene expression. Depletion of either Sox2 or VRK1 caused a reduction of cell proliferation. Sox2 up-regulates VRK1 expression and both proteins cooperate in the activation of CCND1. The accumulation of VRK1 protein downregulates SOX2 expression and both proteins are lost in terminally differentiated cells. Induction of neural differentiation with retinoic acid resulted in downregulation of Sox2 and VRK1 that inversely correlated with the expression of differentiation markers such as N-cadherin, Pax6, mH2A1.2 and mH2A2. Differentiation-associated macro histones mH2A1.2and mH2A2 inhibit CCND1 and VRK1 expression and also block the activation of the VRK1 promoter by Sox2. VRK1 is a downstream target of Sox2 and both form an autoregulatory loop in epithelial cell differentiation.

A genome-wide linkage scan reveals CD53 as an important regulator of innate TNF-alpha levels

Cytokines are major immune system regulators. Previously, innate cytokine profiles determined by lipopolysaccharide stimulation were shown to be highly heritable. To identify regulating genes in innate immunity, we analyzed data from a genome-wide linkage scan using microsatellites in osteoarthritis (OA) patients (The GARP study) and their innate cytokine data on interleukin (IL)-1beta, IL-1Ra, IL-10 and tumor necrosis factor (TNF)alpha. A confirmation cohort consisted of the Leiden 85-Plus study. In this study, a linkage analysis was followed by manual selection of candidate genes in linkage regions showing LOD scores over 2.5. An single-nucleotide polymorphism (SNP) gene tagging method was applied to select SNPs on the basis of the highest level of gene tagging and possible functional effects. QTDT was used to identify the SNPs associated with innate cytokine production. Initial association signals were modeled by a linear mixed model. Through these analyses, we identified 10 putative genes involved in the regulation of TNFalpha. SNP rs6679497 in gene CD53 showed significant association with TNFalpha levels (P=0.001). No association of this SNP was observed with OA. A novel gene involved in the innate immune response of TNFalpha is identified. Genetic variation in this gene may have a role in diseases and disorders in which TNFalpha is closely involved.

A novel mutation in Hr causes abnormal hair follicle morphogenesis in hairpoor mouse, an animal model for Marie Unna Hereditary Hypotrichosis

Hairpoor mice (Hr(Hp)) were derived through N-ethyl-N-nitrosourea (ENU) mutagenesis. These mice display sparse and short hair in the Hr(Hp)/+ heterozygous state and complete baldness in the Hr(Hp)/Hr(Hp) homozygous state. This phenotype was irreversible and was inherited in an autosomal semidominant manner. Hair follicles (HFs) of Hr(Hp)/+ mice underwent normal cycling and appeared normal, although smaller than those of the wild-type mice. In contrast, HFs of Hr(Hp)/Hr(Hp) mice became cyst-like structures by postnatal day (P) 21. The number and length of vibrissae decreased in a dose-dependent manner as the number of mutant alleles increased. A positional candidate gene approach was used to identify the gene responsible for the hairpoor phenotype. Genetic linkage analysis determined that the hairpoor locus is 2 cm from D14Mit34 on chromosome 14. Sequence analysis of the exons of the candidate gene hairless revealed a T-to-A transversion mutation at nucleotide position 403 (exon 2), presumably resulting in abolishment of an upstream open reading frame (uORF). In addition, we also found that the near-naked mouse (Hr(N)), a spontaneously arising mutant, harbors a A402G transition in its genome. Both mutations were in the uATG codon of the second uORF in the 5' UTR and corresponded to the mutations identified in Marie Unna Hereditary Hypotrichosis (MUHH) patients. In the present study we describe the phenotype, histological morphology, and molecular etiology of an animal model of MUHH, the hairpoor mouse.

Functional implications of tetraspanin proteins in cancer biology

Human tetraspanin proteins are a group of 33 highly hydrophobic membrane proteins that can form complexes in cholesterol-rich microdomains, distinct from lipid rafts, on the cell surface in a dynamic and reversible way. These complexes are composed of a core of several tetraspanin proteins that organize other membrane proteins such as integrins, human leukocyte antigen (HLA) antigens and some growth factor receptors. Although most tetraspanin proteins have been studied individually, tetraspanin proteins and their complexes can have effects on cellular adhesion and motility, interactions with stroma or affect signaling by growth factors, and for most of them no ligand has been identified. Functionally these proteins have been mostly studied in cells of lymphoid lineage, but they are present in all cell types. Data is also available for some tumors, where some tetraspanins have been identified as metastasis suppressors, but their significance is still not clear. Some of their implications in tumor biology and the areas that deserve further study are outlined.

The CD53 and CEACAM-1 genes are genetic targets for early B cell factor

Early B cell factor (EBF)-1 is a transcription factor known to be of critical importance for early B lymphocyte development. EBF-1 has been shown to directly interact with and regulate expression of a set of genes involved in the functional formation of the pre-B cell receptor, but the dramatic phenotype observed in the EBF-1-deficient mice suggests that several additional genes are activated by this protein. In order to identify additional target genes for EBF-1, we transduced a hematopoietic progenitor cell line, BaF/3, with an EBF-1-encoding retrovirus and investigated the induced gene expression pattern by micro-arrays. This analysis suggested that among others, the CD53 and the carcinoembryonic antigen-related cell adhesion molecule (CEACAM)-1 genes both were induced by ectopic expression of EBF-1. Identification of the 5' end of the cDNA enabled the identification of promoter elements with functional binding sites for EBF-1 and ability to respond to EBF-1 expression in transient transfection assays. These data suggest that CD53 and CEACAM-1 are direct genetic targets for EBF-1, providing additional information concerning the activity of this crucial transcription factor in hematopoiesis.

Peroxide-inducible Ets-1 mediates platelet-derived growth factor receptor-alpha gene transcription in vascular smooth muscle cells

Platelet-derived growth factor (PDGF) has been implicated in the pathogenesis of vascular occlusive disorders such as atherosclerosis and restenosis in part due to its regulation of smooth muscle cell phenotype. The molecular mechanisms regulating the expression of PDGF-Ralpha, which binds all known dimeric forms of PDGF except PDGF-DD, are poorly understood. Here we demonstrate that the winged helix-turn-helix proto-oncogene Ets-1 controls PDGF-Ralpha transcription and mRNA expression in smooth muscle cells. Mutational analysis, electrophoretic mobility shift assay, and chromatin immunoprecipitation revealed the existence of a reverse Ets binding motif (-45TTCC-42) in the proximal region of the PDGF-Ralpha promoter, which bound both recombinant and endogenous Ets-1. Ets-1-inducible PDGF-Ralpha expression depended on the integrity of both the -45TTCC-42 motif and the -61G10(-52) element, which resides upstream of -45TTCC-42 and mediates Sp1 induction. Hydrogen peroxide (H2O2) at nanomolar concentrations stimulated levels of Ets-1 and increased PDGF-Ralpha transcription and mRNA expression without affecting Sp1 expression. H2O2 activation of the PDGF-Ralpha promoter was abolished by disrupting -45TTCC-42 or -61G10(-52). These studies identify a functional Ets motif in the PDGF-Ralpha promoter that plays a pivotal role in agonist-inducible PDGF-Ralpha transcription.

Aberrant expression of tetraspanin molecules in B-cell chronic lymphoproliferative disorders and its correlation with normal B-cell maturation

Tetraspanin proteins form signaling complexes between them and with other membrane proteins and modulate cell adhesion and migration properties. The surface expression of several tetraspanin antigens (CD9, CD37, CD53, CD63, and CD81), and their interacting proteins (CD19, CD21, and HLA-DR) were analyzed during normal B-cell maturation and compared to a group of 67 B-cell neoplasias. Three patterns of tetraspanin expression were identified in normal B cells. The first corresponded to bone marrow CD10(+) B-cell precursors (BCP) which showed high expression of CD81 and CD9, low reactivity for CD53 and negativity for CD37. CD10(-) B-lymphocytes showed downregulation of CD9/CD81 and upregulation of CD53/CD37. Plasma cells showed re-expressed CD9 and downregulated CD37. Hierarchical clustering analysis of flow cytometry immunophenotypic data showed a good correlation between the tumor differentiation stage and the pattern of tetraspanin expression, with all analyzed individual samples classified into three major groups, independently of their normal or neoplastic origin. Despite this, neoplastic B-cells frequently showed aberrantly high/low expression of the different markers analyzed. Interestingly, in B-cell chronic lymphocytic leukemia, abnormal expression of CD53 and CD9 were associated with different patterns of disease infiltration, which would support the role of these molecules on modulating adhesion and migration of neoplastic B cells.

Gene expression versus sequence for predicting function: Glia Maturation Factor gamma is not a glia maturation factor

It is standard practice, whenever a researcher finds a new gene, to search databases for genes that have a similar sequence. It is not standard practice, whenever a researcher finds a new gene, to search for genes that have similar expression (co-expression). Failure to perform co-expression searches has lead to incorrect conclusions about the likely function of new genes, and has lead to wasted laboratory attempts to confirm functions incorrectly predicted. We present here the example of Glia Maturation Factor gamma (GMF-gamma). Despite its name, it has not been shown to participate in glia maturation. It is a gene of unknown function that is similar in sequence to GMF-beta. The sequence homology and chromosomal location led to an unsuccessful search for GMF-gamma mutations in glioma. We examined GMF-gamma expression in 1432 human cDNA libraries. Highest expression occurs in phagocytic, antigen-presenting and other hematopoietic cells. We found GMF-gamma mRNA in almost every tissue examined, with expression in nervous tissue no higher than in any other tissue. Our evidence indicates that GMF-gamma participates in phagocytosis in antigen presenting cells. Searches for genes with similar sequences should be supplemented with searches for genes with similar expression to avoid incorrect predictions.

c-Jun phosphorylation by the human vaccinia-related kinase 1 (VRK1) and its cooperation with the N-terminal kinase of c-Jun (JNK)

The VRK1 kinase is a novel Ser-Thr kinase in the human kinome that diverged from the casein kinase 1 branch. These kinases phosphorylate transcription factors related to stress responses, such as p53. In this report we have studied the phosphorylation of the transcription factor c-Jun in its N-terminal region. The VRK1 protein phosphorylates c-Jun with a Km of 0.4 muM, and is not inhibited by SP600125. VRK1 phosphorylates c-Jun in Ser63 and Ser73 in vitro, the same residues targeted by the N-terminal kinase of c-Jun (JNK). This phosphorylation induces the stabilization and accumulation of the c-Jun protein. VRK1 phosphorylates the endogenous c-Jun in Ser63. VRK1 activates c-Jun dependent transcription, which is dependent on phosphorylation of Ser63 and Ser73. The c-Jun with Ser63Ala and Ser73Ala substitutions is not transcriptionally active when cotransfected with VRK1. VRK1 interacts with c-Jun but not with JNK. The cotransfection of VRK1 and JNK has an additive effect on the transcriptional activation of c-Jun indicating that they can cooperate when both are at suboptimal dose; otherwise, maximum effect by one of them prevents the effect of the other. The VRK1-c-Jun connection represents a component of a new signaling pathway whose upstream elements remain to be identified.

Injury‐induced NF‐κB activation in the hippocampus: implications for neuronal survival

Nuclear factor (NF)-kappaB p50 protein is involved in promoting survival in hippocampal neurons after trimethyltin (TMT)-injury. In the current study, hippocampal NF-kappaB activity was examined and quantitated from transgenic kappaB-lacZ reporter mice after chemical-induced injury. NF-kappaB activity was localized primarily to hippocampal neurons and significantly elevated over that in saline-treated mice between 4 and 21 days after TMT injection. Seven days after TMT injection, a timepoint of elevated NF-kappaB activity, gene expression in the hippocampus was studied by microarray analysis through comparison of expression profiles between treated nontransgenic and p50-null mice with their saline-injected controls. Seventeen genes increased in nontransgenic TMT-treated mice relative to saline-treated as well as showing no increase in p50-null mice, indicating a role for p50 in their regulation. One of these genes, the Na+, K+-ATPase-gamma subunit, was detected in brain for the first time. Several of the genes modulated by NF-kappaB are potentially related to neuroplasticity, providing additional evidence that this transcription factor is a neuroprotective signal in the hippocampus.

Transcriptional regulation by activation and repression elements located at the 5'-noncoding region of the human alpha9 nicotinic receptor subunit gene

The alpha9 subunit is a component of the neuronal nicotinic acetylcholine receptor gene superfamily that is expressed in very restricted locations. The promoter of the human gene has been analyzed in the human neuroblastoma SH-SY5Y, where alpha9 subunit expression was detected, and in C2C12 cells that do not express alpha9. A proximal promoter region (from -322 to +113) showed maximal transcriptional activity in SH-SY5Y cells, whereas its activity in C1C12 cells was much lower. Two elements unusually located at the 5'-noncoding region exhibited opposite roles. A negative element located between +15 and +48 appears to be cell-specific because it was effective in C2C12 but not in SH-SY5Y cells, where it was counterbalanced by the presence of the promoter region 5' to the initiation site. An activating element located between +66 and +79 and formed by two adjacent Sox boxes increased the activity of the alpha9 promoter about 4-fold and was even able to activate other promoters. This element interacts with Sox proteins, probably through a cooperative mechanism in which the two Sox boxes are necessary. We propose that the Sox complex provides an initial scaffold that facilitates the recruiting of the transcriptional machinery responsible for alpha9 subunit expression.

Gastric cancer related gene expression spectrum in disease pattern of traditional Chinese medicine

AIM

To find difference in gene expression pedigree of gastric carcinoma tissue and different syndrome, and its significance in the exploration of the syndrome typ and diagnosisof gastric carcinoma, with gene diagnosis as well as the use of drugs in its treatment.

METHODS

The gene expression in two TCM syndrome types of gastric carcinoma due to internal stagnancy of pathogenic heat and stagnancy of qi and blood stasis, respectively, including 4 human gastric carcinoma tissues and normal embryo stomach tissue, was analyzed by using 4096 pieces of human full-length genic CDNA expression CMOS chip technology.

RESULTS

The gene expression in the two TCM syndrome types of gastric carcinoma was decreased in their immune associated genes, but increased in cancer-associated genes. Gene expression in the interior stagnancy of toxic heat showed that the body resistance was not weakened, suggesting that there was no deficiency of qi and stagnancy of blood stasis

CONCLUSION

The change in gene expression of gastric cancer is identical, but the gene expression spectrum is different in different types of TCM syndromes.

Apoptosis protection and survival signal by the CD53 tetraspanin antigen

The CD53 antigen is a tetraspanin protein of the lymphoid-myeloid lineage, but its implication in biological effects is hardly known. Radioresistant tumor cells express very high levels of this antigen. We have studied the effect of CD53 antigen ligation on the survival response of tumor cells to serum deprivation, a well-known stimulator of cell death that may mimic the tumor environment; for this aim IR938F and Jurkat cells, a B- and T-cell lymphoma, were used. Ligation of CD53 triggers a survival response and reduces the number of cells that enter apoptosis. In CD53- stimulated cells there is a significant reduction in caspase activation, measured by caspase processing of poly ADP-ribose polymerase, as well as a reduction in the fragmentation of DNA. CD53- stimulated cells also have an increase in the level of bcl-X(L) and a reduction of bax protein, two components of the mitochondrial apoptotic pathway, changing their ratio by 24-fold in the direction of survival. This survival signal appears to be mediated by activation of the AKT, as detected by its phosphorylation in Ser473 upon CD53 ligation. The CD53 antigen interactions might contribute to cell survival in poorly vascularized regions of the tumor mass.

Transient activation of the c-Jun N-terminal kinase (JNK) activity by ligation of the tetraspan CD53 antigen in different cell types

The CD53 antigen is a member of the tetraspanin membrane protein family that is expressed in the lymphoid-myeloid lineage. We have studied the implication of CD53 antigen in signal transduction by determining the effect of its ligation on the c-Jun N-terminal kinase (JNK) in different cell types. Ligation of the rat or human CD53 antigen induces a three- to fourfold transient activation of JNK activity that peaks at 3-5 min. The effect was detected by assaying the endogenous or exogenous (transfected) JNK activity. The JNK response was detected in IR938F cells, a rat B-cell lymphoma, and in Jurkat cells derived from a human T-cell lymphoma. This JNK activation was not mediated by the vav oncogene, and CD53 does not cooperate with CD3 for vav activation. A similar JNK activation was also detected in a human renal carcinoma cell line that was transiently transfected with the human CD53 cDNA to mimic the CD53 ectopic expression in carcinomas. In stable CD53-transfected cells it stimulated Jun-dependent transcriptional activity. We conclude that parts of the cell responses modulated by the CD53 are mediated by JNK activation, and this activation is independent of the different protein interactions that the CD53 protein has on specific cell types.

Down-regulation of macrophage CD9 expression by interferon-gamma

CD9, a member of the tetraspanin family is a cell surface marker expressed on myeloid and nonmyeloid as well as on neoplastic cells. The present study has focused on the role of inflammation and macrophage activation in the regulation of CD9 expression. We report that the expression of CD9 on primary cultures of murine peritoneal macrophages was down regulated by Interferon-gamma, IFN-gamma. This down regulation was concentration-dependent and maximal by 48 h. The changes in surface expression were consistent with similar reductions in CD9 protein and message levels by Western and Northern blot analyses. The mechanism by which IFN-gamma decreases CD9 expression appears to be through the Stat1 signaling pathway as Stat1 knockout mice did not demonstrate any reduction in CD9 expression by IFN-gamma treatment. These results represent the first evidence for the down regulation of CD9 expression with macrophage activation.