Identification of two distinct transactivation domains in the pluripotency sustaining factor nanog

Nanog is a newly identified homeodomain gene that functions to sustain the pluripotency of embryonic stem cells.However,the molecular mechanism through which nanog regulates stem cell pluripotency remains unknown.Mouse nanog encodes a polypeptide of 305 residues with a divergent homeodomain similar to those in the NK-2 family.The rest ofnanog contains no apparent homology to any known proteins characterized so far.It is hypothesized that nanog encodes a transcription factor that regulates stem cell pluripotency by switching on or off target genes.To test this hypothesis,we constructed fusion proteins between nanog and DNA binding domains of the yeast transcription factor Gal4 and tested the transactivation potentials of these constructs.Our data demonstrate that both regions N- and C- terminal to the homeodomain have transcription activities.Despite the fact that it contains no apparent transactivation motifs,the C-terminal domain is about 7 times as active as the N-terminal one.This unique arrangement of dual transactivators may confer nanog the flexibility and specificity to regulate downstream genes critical for both pluripotency and differentiation of stem cells.

<i>Porphyromonas gingivalis</i>-Stimulated TACE Activation for TGF-<i>α</i>Ectodomain Shedding and EGFR Transactivation in Salivary Gland Cells Requires Rac1-Dependent p38 MAPK Membrane Localization

Oral mucosal inflammatory responses to P. gingivalis and its key virulence factor, lipopolysaccharide (LPS), are characterized by a massive rise in proinflammatory cytokine production, up-regu- lation in mitogen-activated protein kinase (MAPK) cascade, and the induction in epidermal growth factor receptor (EGFR) activation. In this study, we report that stimulation of salivary gland acinar cells with P. gingivalis LPS leads to p38 MAPK-dependent release of soluble TGF-α ligand and the increase in EGFR phosphorylation. Further, we show that the LPS-induced TGF-α shedding and EGFR transactivation involve the activation of membrane-associated metalloprotease, TACE also known as ADAM17, through phosphorylation by p38 MAPK, and require Rac1 participation. Moreover, we demonstrate that blocking the Rac1 activation leads to the suppression in the membrane translocation of Rac1 as well as p38, thus indicating that the LPS-elicited p38 membrane recruitment for TACE phosphorylation requires colocalization with Rac1. Hence, our findings imply that Rac1 membrane translocation serves as an essential platform for the localization of p38 with TACE, TGF-α ectodomain shedding, and the EGFR activation.

Effect of Calpain inhibitor I on glucocorticoid receptor-dependent degradation and its transactivation ability

Objective: To investigate the effect of Calpain inhibitor I on glucocorticoid receptor-dependent proteasomal degradation and its transcriptional activity. Methods: After Raw-264.7 cells were treated with Calpain inhibitor I, dexamethasone, or both for about 12 h, the change of glucocorticoid receptor was detected by western blot analysis. COS-7 cells were transfected with PRsh-GRα expression vector and glucocorticoid-responsive receptor pMAMneo-CAT, then the effect of Calpain inhibitor I on glucocorticoid receptor transcriptional activation ability was determined by CAT activity. Results: The glucocorticoid receptor levels decreased after RAW-264.7 cells were treated with dexamethasone for 12 hours, which effect can be inhibited by Calpain inhibitor I to some extent. CAT activity assay showed that Calpain inhibitor I enhance glucocorticoid receptor transcriptional activity. Conclusion: Calpain inhibitor I can inhibit the down-regulation of dexamethasone on glucocorticoid receptor, and enhances glucocorticoid receptor transactivation ability.

Hydrogen sulfide-linked persulfidation of ABI4 controls ABA responses through the transactivation of MAPKKK18 in Arabidopsis

Hydrogen sulfide(H2S)is a signaling molecule that regulates plant hormone and stress responses.The phytohormone abscisic acid(ABA)plays an important role in plant adaptation to unfavorable environmental conditions and induces the persulfidation of L-CYSTEINE DESULFHYDRASE1(DES1)and the production of H2S in guard cells.However,it remains largely unclear how H2S and protein persulfidation participate in the relay of ABA signals.In this study,we discovered that ABSCISIC ACID INSENSITIVE 4(ABI4)acts downstream of DES1 in the control of ABA responses in Arabidopsis.ABI4 undergoes persulfidation at Cys250 that is triggered in a time-dependent manner by ABA,and loss of DES1 function impairs this process.Cys250 and its persulfidation are essential for ABI4 function in the regulation of plant responses to ABA and the H2S donor NaHS during germination,seedling establishment,and stomatal closure,which are abolished in the ABI4Cys250Ala mutated variant.Introduction of the ABI4Cys250Ala variant into the abi4 des1 mutant did not rescue its hyposensitivity to ABA.Cys250 is critical for the binding of ABI4 to its cognate motif in the promoter of Mitogen-Activated Protein Kinase Kinase Kinase 18(MAPKKK18),which propagates the MAPK signaling cascade induced by ABA.Furthermore,the DES1-mediated persulfidation of ABI4 enhances the transactivation activity of ABI4 toward MAPKKK18,and ABI4 can bind the DES1 promoter,forming a regulatory loop.Taken together,these findings advance our understanding of a post-translational regulatory mechanism and suggest that ABI4 functions as an integrator of ABA and MAPK signals through a process in which DES1-produced H2S persulfidates ABI4 at Cys250.

Thymine DNA glycosylase promotes transactivation of β-catenin/TCFs by cooperating with CBP

Thymine DNA glycosylase CrDG）, an enzyme that initiates the repair of G/T and G/U mismatches, has been lately found crucial in em- bryonic development to maintain epigenetic stability and facilitate the active DNA demethylation. Here we report a novel role of TDG in Wnt signaling as a transcriptional coactivator of β-catenin/TCFs complex. Our data show that TDG binds to the transcriptional factor family LEF1/TCFs and potentiates β-catenin/TCFs transactivation, while TDG depletion suppresses Wnt3a-stimulated reporter activity or target gene transcription. Next, we show that CBP, a known coactivator, is also required for TDG function through forming a coopera- tive complex on target promoters. Moreover, there is an elevation of TDG levels in human colon cancer tissue, and knockdown of TDG inhibits proliferation of the colon cells. Overall, our results reveal that TDG, as a new coactivator, promotes β-catenin/TCFs transacti- vation and functionally cooperates with CBP in canonical Wnt signaUng.

EYA4 inhibits hepatocellular carcinoma growth and invasion by suppressing NF-κB-dependent RAP1 transactivation

Background:Our previous studies demonstrated that eyes absent homolog 4(EYA4),a member of the eye devel-opment-related EYA family in Drosophila,is frequently methylated and silenced in hepatocellular carcinoma(HCC)specimens and associated with shorter survival.The current work aimed to explore the mechanisms through which EYA4 functions as a tumor suppressor in HCC.Methods:Stable EYA4-expressing plasmid(pEYA4)transfectants of the human HCC cell lines Huh-7 and PLC/PRF/5(PLC)were established.Xenografts tumors were established via subcutaneous injection of the stable transfectants into BALB/c nude mice.Tissue samples were obtained from 75 pathologically diagnosed HCC patients.Quantitative real-time polymerase chain reaction,Western blotting and immunohistochemistry were performed to determine the expression of EYA4 in cell lines,xenografts and clinical specimens.The cell proliferation,colony formation,invasiveness and tumor formation of stable transfectants were studied.A gene expression microarray was utilized to screen genes regulated by EYA4 expression.The effect of EYA4 on nuclear factor-κB(NF-κB)/RAS-related protein 1(RAP1)signaling was demonstrated through the co-transfection of pEYA4 and Flag-tagged RAS-related protein 1A gene-expressing plasmid(Flag-RAP1A),functional studies,chromatin immunoprecipitation,immunofluorescence staining and cellular ubiquitination assay.Results:The restoration of EYA4 expression in HCC cell lines suppressed cell proliferation,inhibited clonogenic outgrowth,reduced cell invasion and restrained xenograft tumor growth,and Flag-RAP1A reversed the suppressive effects of pEYA4 in vitro.Activation of NF-κB with tumor necrosis factor-α(TNF-α)increased the binding of p65 to the RAP1A gene promoter and up-regulated RAP1 protein expression.The inhibition of NF-κB with BAY 11-7085 and p65 siRNA successfully blocked TNF-α-induced RAP1 up-regulation.EYA4 antagonized the TNF-α-induced phosphoryla-tion and ubiquitination of inhibitor of NF-κBα(IκBα)as well as the nuclear translocation and transactivation of p65,resulting in repressed NF-κB activity and RAP1 expression.Blocking the serine/threonine phosphatase activity of EYA4 with calyculin A notably abrogated its suppressive effect on NF-κB activity.In addition,EYA4 expression was inversely correlated with IκBα/RAP1 activity in clinical HCC specimens.Conclusion:Our findings provide a functional and mechanistic basis for identifying EYA4 as a bona fide tumor sup-pressor that disrupts aberrant activation of the NF-κB/RAP1 signaling pathway and thus orchestrates a physiological impediment to HCC growth and invasion.

Single-molecule imaging reveals the stoichiometry change of epidermal growth factor receptor during transactivation by β_2-adrenergic receptor

Stimulation of G protein-coupled receptors(GPCRs) can lead to the transactivation of the epidermal growth factor receptors(EGFR). The cross-communication between the two signaling pathways regulates several important physiological or pathological processes. However, the molecule mechanism underlying EGFR transactivation remains poorly understood. Here, we aim to study the GPCR-mediated EGFR transactivation process using the single-molecule fluorescence imaging and tracking approach.We found that although EGFR existed as monomers at the plasma membrane of resting cells, they became dimers and thus diffused slower following the activation of β2-adrenergic receptor(β2-AR) by isoproterenol(ISO). We further proved thatβ2-AR-mediated changes of EGFR in stoichiometry and dynamics were mediated by Src kinase. Thus, the observations obtained via the single-molecule imaging and tracking methods shed new insights into the molecular mechanism of EGFR transactivation at single molecule level.

Activation of GABAB receptors protects cerebellar granule neurons from apoptosis via IGF-I receptor transactivation

γ-amidobutyric acid (GABA) is a major inhibitory neurotransmitter in the central nervous system and mediates fast synaptic inhibition through GABAA and GABAC

Study of transactivating effect of pre-S2 protein of hepatitis B virus and cloning of genes transactivated by pre-S2 protein with suppression subtractive hybridization

AIM： To investigate the transactivating effect of pre-S2 protein of hepatitis B virus （HBV） and construct a subtractive cDNA library of genes transactivated by pre-S2 protein with suppression subtractive hybridization （SSH） technique, and to pave the way for elucidating the pathogenesis of HBV infection. METHODS： pcDNA3.1（-）-pre-S2 containing pre-S2 region of HBV genome was constructed by routine molecular methods. HepG2 cells were cotransfected with pcDNA3.1 （-）-pre-S21pSV-lacZ and empty pcDNA3.1（-）/pSV-lacZ. After 48 h, cells were collected and detected for the expression of β-galactosidase （β-gal）. SSH and bioinformatics techniques were used, the mRNA of HepG2 cells transfected with pcDNA3.1（-）-pre-S2 and pcDNA3.1（-） empty vector was isolated, respectively, cDNA was synthesized. After digestion with restriction enzyme RsaI, cDNA fragments were obtained. Tester cDNA was then divided into two groups and ligated to the specific adaptor 1 and adaptor 2, respectively. After tester cDNA was hybridized with driver cDNA twice and underwent two times of nested PCR, amplified cDNA fragments were subcloned into pGEM-Teasy vectors to set up the subtractive library. Amplification of the library was carried out with E.coli strain DH5α The cDNA was sequenced and analyzed in GenBank with Blast search after PCR. RESULTS： The pre-S2 mRNA could be detected in HepG2 cells transfected with pcDNA3.1（-）-pre-S2 plasmid. The activity of β-gal in HepG2 cells transfected with pcDNA3.1 （-）-pre-S2/pSV-lacZ was 7.0 times higher than that of control plasmid （P〈0.01）. The subtractive library of genes transactivated by HBV pre-S2 protein was constructed successfully. The amplified library contains 96 positiveclones. Colony PCR showed that 86 clones contained 200-1 000 bp inserts. Sequence analysis was performed in 50 clones randomly, and the full length sequences were obtained with bioinformatics method and searched for homologous DNA sequence from GenBank, altogether 25 coding sequences were obtained, these cDNA sequences might be the target genes transactivated by pre-S2 protein. CONCLUSION： The pre-S2 protein of HBV has transactivating effect on SV40 early promoter. The obtained sequences may be target genes transactivated by pre-S2 protein among which some genes coding proteins involved in cell cycle regulation, metabolism, immunity, signal transcluction and cell apoptosis.This finding brings some new clues for studying the biological functions of pre-S2 protein and further understanding of HBV hepatocarcinogesis.

Lysophosphatidic acid transactivates both c-Met and epidermal growth factor receptor, and induces cyclooxygenase-2 expression in human colon cancer LoVo cells

AIM： To examine whether lysophosphatidic acid （LPA） induces phosphorylation of c-Met and epidermal growth factor receptor （EGFR）, both of which have been proposed as prognostic markers of colorectal cancer, and whether LPA induces cyclooxygenase-2 （COX-2） expression in human colon cancer cells. METHODS： Using a human colon cancer cell line, LoVo cells, we performed immunoprecipitation analysis, followed by Western blot analysis. We also examined whether LPA induced COX-2 expression, by Western blot analysis. RESULTS： Immunoprecipitation analysis revealed that 10 μmol/L LPA induced tyrosine phosphorylation of c-Met and EGFR in LoVo cells within a few minutes. We found that c-Met tyrosine phosphorylation induced by LPA was not attenuated by pertussis toxin or a matrix metalloproteinase inhibitor, in marked contrast to the results for EGFR. In addition, 0.2-40 IJmol/L LPA induced COX-2 expression in a dose-dependent manner. CONCLUSION： Our results suggest that LPA acts upstream of various receptor tyrosine kinases （RTKs） and COX-2, and thus may act as a potent stimulator of colorectal cancer. 2005 The WJG Press and Elsevier Inc. All rights reserved.

Subcloning and Expression of Human Papillomavirus Type 16 E2 Gene in E.Coli

By using molccular doning technique,the E2 gene of human papillomavirus type 16 wasexpressed in E.coli.The 3.2 kb fragment containing the E2 gene was cut out from HPV16 genomeand blunted with nuelease S1.The plasmid pBD2 DNA was linearized with Hind Ⅲ and bluntedwith nuclasc S1 too.Afler ligation,thc ligsted DNA was used to transform E.coli BMH 71-18.The positive colonies were screened by in situ hybridization technique,and proceedcd to DNA analy-sis and proton analysis.The purified expressed protein was used to run immunoclctrophoreesis withantiserum against pBD2.We concktudcd that thc expressed protcin was a fusion protein ofbeta-galae-sidasc-E2 protein.

Identification of genes upregulated by recombinant interferon-alpha in HepG2 cells by suppressive subtractive hybridization analysis

BACKGROUND: Interferon-alpha (IFN-alpha) is an important cytokine with multiple functions, but the target genes transactivated by IFN-alpha remain largely unknown. A study of such genes will help to understand the mechanism of function of IFN-alpha. To isolate the gene transcripts specifically upregulated by IFN-alpha in HepG2 cells, we conducted suppressive subtractive hybridization (SSH) analysis. METHODS: SSH was used to analyze the target genes transactivated by recombinant IFN-alpha protein, and a subtractive cDNA library was constructed from HepG2 cells treated with recombinant IFN-alpha (rIFN-alpha, 2000 IU/ml) for 16 hours as tester, and cells not treated with rIFN-alpha as driver. The SSH PCR products from the library were cloned into pGEM-T easy vector and with BLASTX, the positive clones were randomly selected, sequenced and compared to the database in GenBank of the 35 differentially expressed gene fragments from the library, 6 clones showed significant homology to other known proteins. RESULTS: The subtractive cDNA library of genes upregulated by IFN-alpha was constructed successfully, rIFN-alpha upregulated the expression of the RAN binding protein 5 (RANBP5), NADH dehydrogenase, exosome component 3 (EXOSC3), zinc finger RNA binding protein, Dickkopf homolog 1 (DKK1) and acetyl-coenzyme A acetyltransferase 2 (ACAT2). CONCLUSIONS: These results suggest that rIFN-alpha can upregulate the expression of important genes to exert its functions, and provide new clues for discovering the molecular mechanisms of action of IFN-alpha.

A Toxicological Assessment of Endocrine Disrupting Chemicals Found in the BMW (Border, Midland and Western) Region of Ireland

A battery of tests was established to determine the oestrogenic, mutagenic and genotoxic potential of two categories of endocrine disrupting chemicals (EDCs), phthalates and alkylphenols. Diisononylphthalate (DINP), diethylhexylphthalate (DEHP), dibutylphthalate (DBP), diisododecylphthalate (DIDP) and 4-nonylphenol (4-NP) were oestrogenic in the yeast estrogen screen (YES) assay and potently oestrogenic in the MVLN and E-SCREEN assays at environmentally relevant concentrations. DINP and 4-NP were mutagenic in the Ames assay and also induced significant levels of unscheduled DNA synthesis and DNA strand breakage. Significant induction in the percentage of cells containing micronuclei was observed after treatment with DINP, DEHP and 4-NP. In addition, sewage effluents from sewage treatment plants (STPs) in the Border, Midlands and Western (BMW) region of Ireland were significantly oestrogenic in the YES assay. Moreover, analysis of levels of phthalates and alkylphenol identified in Irish rivers receiving treated effluent showed potent oestrogenicity in the YES assay. The proliferative and genotoxic ability of the phthalates and alkylphenol, and the oestrogenicity of the treated effluents reported here, is significant as these EDCs and EDCs within the effluent may play a role in the etiology of human abnormalities.

Transactivating effect of complete S protein of hepatitis B virus and cloning of genes transactivated by complete S protein using suppression subtractive hybridization technique

AIM: To investigate the transactivating effect of complete S protein of hepatitis B virus (HBV) and to construct a subtractive cDNA library of genes transactivated by complete S protein of HBV by suppression subtractive hybridization (SSH) technique and to clone genes associated with its transactivation activity, and to pave the way for elucidating the pathogenesis of hepatitis B virus infection. METHODS: pcDNA3.1(-)-complete S containing full-length HBV S gene was constructed by insertion of HBV complete S gene into BamH I/Kpn I sites. HepG2 cells were cotransfected with pcDNA3.1(-)-complete S and pSV-lacZ. After 48 h, cells were collected and detected for the expression of β-galactosidase (β-gal). Suppression subtractive hybridization and bioinformatics techniques were used. The mRNA of HepG2 cells transfected with pcDNA3.Incomplete S and pcDNA3.1(-) empty vector was isolated, and detected for the expression of complete S protein by reverse transcription polymerase chain reaction (RT-PCR) method, and cDNA was synthesized. After digestion with restriction enzyme RsaI, cDNA fragments were obtained. Tester cDNA was then divided into two groups and ligated to the specific adaptors 1 and 2, respectively. After tester cDNA had been hybridized with driver cDNA twice and underwent nested PCR twice, amplified cDNA fragments were subcloned into pGEM-Teasy vectors to set up the subtractive library. Amplification of the library was carried out within E. coli strain DH5α. The cDNA was sequenced and analyzed in GenBank with BLAST search after polymerase chain reaction (PCR) amplification. RESULTS: The complete S mRNA could be detected by RT-PCR in HepG2 cells transfected with the pcDNA3.1(-)-complete S. The activity of β-gal in HepG2 cells transfected with the pcDNA3.1(-)-complete s was 6.9 times higher than that of control plasmid. The subtractive library of genes transactivated by HBV complete S protein was constructed successfully. The amplified library contains 86 positive clones. Colony PCR showed that 86 clones contained DNA inserts of 200-1 000 bp, respectively. Sequence analysis was performed in 35 clones randomly, and the full length sequences were obtained with bioinformatics method and searched for homologous DNA sequence from GenBank, altogether 33 coding sequences were obtained. These cDNA sequences might be target genes transactivated by complete S protein of HBV. Moreover, two unknown genes were discovered, full length coding sequences were obtained by bioinformatics techniques, one of them was named complete S transactivated protein 1 (CSTP1) and registered in GenBank (AY553877). CONCLUSION: The complete S gene of HBV has a transactivating effect on SV40 early promoter. A subtractive cDNA library of genes transactivated by HBV complete S protein using SSH technique has been constructed successfully. The obtained sequences may be target genes transactivated by HBV complete S protein among which some genes coding proteins are involved in cell cycle regulation, metabolism, immunity, signal transduction, cell apoptosis and formation mechanism of hepatic carcinoma.

Relationship between polymorphism of class Ⅱ transactivator gene promoters and chronic hepatitis B

AIM: To investigate the relationship between the polymorphism of class Ⅱ transactivator (CIITA) gene promoters and chronic hepatitis B (CHB). METHODS: Genomic DNA was prepared from peripheral blood leukocytes. Promoters Ⅰ,Ⅲ and Ⅳ of gene were analyzed respectively with polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) in 65 patients with CHB, 26 patients with acute hepatitis B (AHB) and 85 normal controls. RESULTS: No abnormal migration was found in PCR-SSCP analysis of the three promoters in the three groups. Also, no sequential difference was observed at the three promoters among the CHB patients, AHB patients and normal controls. CONCLUSION: No polymorphism in promoters I, III and IV of CIITA gene exists in CHB patients, ABH patients and normal controls, suggesting that the promoter of CIITA gene might be a conserved domain.

In Vitro Biological Activity of Anti-C Ⅱ TA Hammerhead Ribozyme——A Novel Approach for Autoimmune Diseases

This study investigated the feasibility of using an hammerhead ribozyme against C Ⅱ TA, a major regulator of MHC Ⅱ antigens, to repress the expression of MHC Ⅱ molecules on Hela cells. A hammerhead ribozyme (Rz464) specific to 463-465 GUC triplet of C Ⅱ TA and its target gene were transcribed, then mixed up and incubated in vitro . The cleavage products were analyzed by PAGE and silver staining. Rz464 was then inserted into the pIRES2 EGFP vector (pRz464). Stable transfectants of Hela with pRz464 were tested for class Ⅱ MHC induction by recombinant human interferon gamma (IFN γ). mRNA of C Ⅱ TA was measured by RT PCR. Our results showed that Rz464 could exclusively cleave C Ⅱ TA RNA. When induced with IFN γ, the expression of HLA DR, DP, DQ on pRz464 + Hela was induced, and the mRNA content of C Ⅱ TA decreased too. It is concluded that Rz464 could inhibit C Ⅱ TA and thus the family of genes was regulated by C Ⅱ TA:MHC Ⅱ molecules. These results provided insight into the future application of Rz464 as a new nucleic acid drug against auto immune diseases.

Establishment of a tetracycline-off and heat shock-on gene expression system in tobacco

The tetracycline （Tet）-off gene expression regulation system based on the TetR-VP16/Top10 construct has not been widely utilized in plants, for its highly expressed TetR-VP16 activator is toxic to some plants and repeatedly replenishing tetracycline to turn off the constitutively active system is a tedious process. To solve these problems, a Tet-off and heat shock （HS）-on gene expression regulation system was constructed in this study. This system is composed of a chimeric transactivator gene TetR-HSF that is derived from a Tet repressor （TetR） and a HS transcription factor （HSF） controlled by a HS promoter HSP70m, and a Tet operator containing hybrid promoter, Om35S, that drives expression of the β-glucuronidase （GUS） gene. The resultant system yields a GUS expression pattern similar to that of the HSP70m promoter under inducing temperatures and at 35 and 40℃ drives GUS expression to a similar level as the Cauliflower mosaic virus （CaMV） 35S promoter. Further examination revealed that the TetR-HSF and GUS genes were induced by HS, reaching peak expression after 1 and 6 h treatment, respectively, and the HS induction of the expression system could be inhibited by Tet. This system will provide a useful tool for transgenic studies of plants in the laboratory and in the field, including transgene function analysis, agronomic trait improvement, biopharmaceutical protein production and others.

The enhancement of astrocytic-derived monocyte chemoattractant protein-1 induced by the interaction of opiate and HIV tat in HIV-associated dementia

HIV-associated dementia(HAD)is a public health problem and is particularly prevalent in drug abusers.The neuropathogenesis of human immunodeficiency virus(HIV)infection involves a complex cascade of inflammatory events,including monocyte/macrophage infiltration in the brain,glial immune activation and release of neurotoxic substances.In these events,astrocytic-derived monocyte chemoattractant protein-1(MCP-1)plays an important role,whose release is elevated by HIV transactivator of transcription(HIV tat)and could be further elevated by opiates.This review will also consider some critical factors and events in MCP-1 enhancement induced by the interactions of opiate and HIV tat,including the mediating role of mu opioid receptor(MOR)and CCR2 as well as the possible signal transduction pathways within the cells.Finally,it will make some future perspectives on the exact pathways,new receptors and target cells,and the vulnerability to neurodegeneration with HIV and opiates.

Expression of CⅡTA Gene in Five Human Malignant Hematological Cell Lines and Its Significance

The role of MHC class Ⅱ transactivator (CⅡTA) in constitutive or IFN-γ inducible expression of HLA molecules in human malignant hematological cell lines was investigated. The expression of HLA molecules and CⅡTA protein was detected by Western blot, immunohistochemistry and flow cytometry. The expression of CⅡTA gene was determined by RT-PCR. The capability of peripheral blood T cell reaction stimulated by tumor cells was monitored by mixed lymphocyte reaction. It was found that the HLAⅡ-positive tumor cells expressed the CⅡ TA quite well, and the expression of HLAⅠ+Ⅱ was increased in the tumor cells with constitutive or inducible expression of CⅡ TA after induced by IFN-γ. The tumor cells which did not express CⅡ TA after induced by IFN- γ were not response to the expression of HLAⅡ promoted by IFN- γ. It suggests a correlation between the inability of some malignant hematological cell lines in response to IFN-γ for HLA expression and the deficiency in the inducible expression of CⅡTA, indicating CⅡ TA might take part in the regulation of HLA Ⅰ+Ⅱ expression in the tumor cells, which might play an important role in tumor immunologic escape.

Functional study of p38 mitogen-activated protein kinase based on cell-penetrating peptide delivery system

Objective p38 Mitogen-activated protein kinase （MAPK） is a crossing center of various pathways. In this study, protein transduction system based on human immunodeficiency virus （HIV）-1 transactivator of transcription （TAT）, which is an efficient delivery peptide of the foreign proteins into cells, was employed to study p38 MAPK functions in eukaryotic cells. Methods p38 And its dominant negative form, p38AF, were constructed into pET-His-TAT vector correctly to verify that the recombinant plasmids were well-founded through restriction enzyme digestion and DNA sequencing. The two proteins, His-TAT-p38 and His-TAT-p38AF, were expressed and purified in Escherichia coli by SDS-PAGE. Then they were incubated with ECV304 cells respectively and readily transduced into cells in a time-dependent and dose-dependent manner. The cells were stimulated by sorbitol. Activating transcription factor （ATF） 2 phosphorylation level was checked using Western blot to assess the activity of endogenous p38. Results Compared with controls, it was found that His-TAT-p38 increased the level ofATF2 phosphorylation in sorbitol-stimulated ECV304 cells, while His-TAT-p38AF inhibited it, indicating p38 MAPK protein delivery system based on TAT was constructed successfully. TAT-p38 and its dominant negative form possessed high biological activity after transduction into ECV304 cells by TAT protein delivery system. The results showed that p38AF fused with TAT could inhibit the transduction of endogenous p38 signal pathway in part, and other pathway might regulate p38 phosphorylation. Conclusions Our study provides a novel pathway to inhibit p38 signal pathway and establish a new method to study p38 function.