Reconstitution of high affinity leukaemia inhibitory factor (LIF) receptors in haemopoietic cells transfected with the cloned human LIF receptor

cDNA clones encoding the human leukaemia inhibitory factor (hLIF) receptor were isolated by screening a placental cDNA expression library in COS-7 cells with 125I-hLIF. The cloned LIF receptor is a member of the haemopoietin receptor family and comprises a signal sequence (44 amino acids), an extracellular region of two haemopoietin receptor domains and three fibronectin type III domains (789 amino acids), a transmembrane domain (26 amino acids) and a cytoplasmic domain (238 amino acids). The LIF receptor is expressed in COS-7 cells as a 190 kDa glycoprotein that specifically binds human LIF with low affinity, but does not bind mouse LIF. Clones encoding a soluble form of the homologous mouse LIF receptor have been isolated, suggesting complex interactions between the various forms of LIF ligand and receptor in vivo. The LIF receptor is most related to the gp130 signal-transducing component of the IL-6 receptor, a feature that may provide a molecular basis for the intertwined biologies of LIF and IL-6 in the absence of obvious structural similarly between the ligands. Mouse B9 plasmacytoma cells transfected with the human LIF receptor display novel high affinity LIF receptors that are presumed to consist of transfected receptors in association with endogenous mouse high affinity-converting subunits. Unlike the low affinity human LIF receptor, the mixed species high affinity receptor is capable of binding mouse LIF.

Protection of xeno-hepatocytes from complement-mediated cytolysis by transduction with homologous restriction factor 20 gene using retroviral vector

Xeno-hepatocyte transplantation has the possibility to substitute for clinical liver transplantation in certain restricted hepatic diseases such as inherited metabolic disorders. To overcome human complement-dependent cytotoxicity on xeno-hepatocytes, the effectiveness of ex vivo transfer with the homologous restriction factor 20 (HRF20, CD59) gene was examined on primary-cultured xeno-hepatocytes using a retroviral vector. Primary-cultured rat hepatocytes transduced with HRF20 cDNA expressed HRF20 antigen by flow cytometric analysis and showed the integration of HRF20 cDNA to the genomic DNA by the polymerase chain reaction. The viability of rat hepatocytes incubated with 50% human serum was decreased due to complement-dependent cytotoxicity, whereas that of the transfectant was significantly protected (77.2+/-9.4 vs. 97.8+/-5.2%, p < 0.01). It was concluded that primary-cultured xeno-hepatocytes transduced with HRF20 cDNA using a retroviral vector could escape complement-dependent cytolysis by human serum.

Colon epithelium can be transiently transfected with liposomes, calcium phosphate precipitation and DEAE dextran in vivo

BACKGROUND

The introduction of recombinant DNA into cells is the initial step toward the development of gene therapy. It has been shown that cationic liposomes are useful vehicles to introduce DNA into colon epithelial cells in vivo.

METHODS

In the present study we compared the efficacy of different nonviral transfection methods into the colon wall. In anesthetized rats, a double balloon catheter was advanced into the colon and a chloramphenicol acetyltransferase (CAT) reporter plasmid complexed to liposomes, mixed with DEAE dextran, or precipitated with calcium phosphate was instilled. Following 2 days CAT activity was determined in the transfected colon segments.

RESULTS

DEAE dextran and liposomes were more effective than calcium phosphate, whereas naked DNA was not taken up by the colon epithelial cells. Reporter gene expression was dose-dependent. Expressing cell types did not differ utilizing the various transfection methods as judged by X-gal staining of colon sections after transfection with a LacZ reporter plasmid.

CONCLUSION

These data indicate that in addition to liposomes, plasmid DNA mixed with DEAE dextran can be taken up by colon epithelial cells. This transfection techniques may prove useful in the development of gene therapy approaches for colon disease.

Integration of Trypanosoma cruzi kDNA minicircle sequence in the host genome may be associated with autoimmune serum factors in Chagas disease patients

Integration of kDNA sequences within the genome of the host cell shown by PCR amplification with primers to the conserved Trypanosoma cruzi kDNA minicircle sequence was confirmed by Southern hybridization with specific probes. The cells containing the integrated kDNA sequences were then perpetuated as transfected macrophage subclonal lines. The kDNA transfected macrophages expressed membrane antigens that were recognized by antibodies in a panel of sera from ten patients with chronic Chagas disease. These antigens barely expressed in the membrane of uninfected, control macrophage clonal lines were recognized neither by factors in the control, non-chagasic subjects nor in the chagasic sera. This finding suggests the presence of an autoimmune antibody in the chagasic sera that recognizes auto-antigens in the membrane of T. cruzi kDNA transfected macrophage subclonal lines.

Insulin receptor substrate-1-mediated enhancement of growth hormone-induced mitogen-activated protein kinase activation

Interaction of GH with the cell-surface GH receptor (GHR) causes activation of the GHR-associated tyrosine kinase, JAK2, and consequent triggering of signaling cascades including the STAT, Ras/Raf/MEK1/MAP kinase, and insulin receptor substrate-1(IRS-1)/PI3kinase pathways. We previously showed that IRS- and GHR-deficient 32D cells that stably express the rabbit GHR and rat IRS-1 (32D-rbGHR-IRS-1) exhibited markedly enhanced GH-induced proliferation and MAP kinase (ERK1 and ERK2) activation compared with cells expressing only the GHR (32D-rbGHR). We now examine biochemical mechanism(s) by which IRS-1 augments GH-induced MAP kinase activation. Time-course experiments revealed a similarly transient (maximal at 15 min) GH-induced ERK1 and ERK2 activation in both 32D-rbGHR and 32D-rbGHR-IRS-1 cells, but, consistent with our prior findings, substantially greater activation was seen in the IRS-1-containing cells. In both cells, GH-induced MAP kinase activation was markedly blunted by the MEK1 inhibitor, PD98059, but not by the PKC inhibitor, GF109203X. Interestingly, pretreatment with the PI3K inhibitor, wortmannin (EC50 approximately 10 nM), significantly reduced GH-induced MAP kinase activation in both 32D-rbGHR and 32D-rbGHR-IRS-1 cells. This same pattern in both cells of IRS-1-dependent augmentation and IRS-1-independent wortmannin sensitivity was also observed for GH-induced activation of Akt and MEK1 (using state-specific antibody blotting for both), despite the lack of difference in GHR, JAK2, SHP-2, p85, Akt, Ras, Raf-1, MEK1, ERK1, or ERK2 abundance between the two cells. A different PI3K inhibitor, LY294002 (50 microM), substantially inhibited (roughly 72%) GH-induced MAP kinase activation in 32D-rbGHR-IRS-1 cells, but only marginally (and statistically insignificantly) inhibited GH-induced MAP kinase activation in 32D-rbGHR cells. Because GH-induced Akt activation was completely inhibited in both cells by the same concentration of LY294002, these findings indicate that the wortmannin sensitivity of both the IRS-1-independent and -dependent GH-induced MAP kinase activation may reflect the activity of another wortmannin-sensitive target(s) in addition to PI3K in mediation of GH-induced MAP kinase activation in these cells. Notably, GH-induced STAT5 tyrosine phosphorylation, unlike Akt or MAPK activation, did not differ between the cells. Finally, while GH promoted accumulation of activated Ras in both cells, both basal and GH-induced activated Ras levels were greater in cells expressing IRS-1 than in 32D-rbGHR cells. These data indicate that while GH induces tyrosine phosphorylation of STAT5 and activation of the Ras/Raf/MEK1/MAPK and PI3K pathways, IRS-1 expression augments the latter two more than the former.

Thyroid receptor activator molecule, TRAM-1, is an androgen receptor coactivator

An androgen receptor (AR) interacting protein was isolated from a HeLa cell complementary DNA library by two-hybrid screening in yeast using the AR DNA and ligand binding domains [amino acids (aa) 481-919] as bait. AR binding of the protein in yeast was dependent on the presence of testosterone or dihydrotestosterone (DHT). The isolated protein is identical to thyroid receptor activator molecule TRAM-1 but lacking aa 1-458. TRAM-1 is a steroid receptor coactivator-3 (SRC-3) subtype. In affinity matrix assays, 35S-labeled TRAM-1 bound the GST-AR ligand binding domain (aa 624-919) and GST-AR N-terminal and DNA binding domains (aa 1-660), but not the GST-AR DNA binding domain (aa 544-634) alone. Coexpression of TRAM-1 increased DHT-dependent AR transactivation 5-fold and constitutive activity of AR (aa 1-660) N-terminal and DNA-binding domains increased 9-fold. Full-length TRAM-1 (aa 1-1424) and the partial (aa 459-1424) were AR and GR coactivators as was SRC-1. In human testis, immunostaining of SRC-3 colocalized with AR in nuclei of Sertoli cells and peritubular myoid cells, indicating it could function as an AR coactivator in these cells. SRC-3 was also present in nuclei of spermatogenic cells where AR was not expressed, suggesting it might also be a coactivator with other nuclear receptors that regulate spermatogenesis.

The role of CBP in estrogen receptor cross-talk with nuclear factor-kappaB in HepG2 cells

Functional interactions or cross-talk between ligand-activated nuclear receptors and the proinflammatory transcription factor nuclear factor-kappaB (NF-kappaB) may play a major role in ligand-mediated modification of diseases processes. In particular, the cardioprotective effects of estrogen replacement therapy are thought to be due in part to the ability of ligand-bound estrogen receptor (ER) to inhibit NF-kappaB function. In the current study 17beta-estradiol-bound ERalpha interfered with cytokine-induced activation of a NF-kappaB reporter in HepG2 cells. The estrogen metabolite, 17alpha-ethinyl estradiol, and the phytoestrogen, genistein, were also effective inhibitors of NF-kappaB activation, whereas tamoxifen, 4-hydroxytamoxifen, and raloxifene were inactive. This inhibition was reciprocal, as NF-kappaB interfered with the trans-activation properties of ERalpha. Ligand-bound ERalpha did not inhibit NF-kappaB binding to DNA, but it did decrease the histone acetyltransferase activity required for NF-kappaB transcriptional activity. Coexpression of the transcription coactivator CREB binding protein (CBP), but not steroid receptor coactivator 1a, reversed the ERalpha-mediated inhibition of NF-kappaB activity. Mammalian two-hybrid experiments also revealed that ligand-bound ERalpha can interact functionally with CBP-NF-kappaB complexes. We suggest that CBP targeting by ERalpha results in the inhibition of NF-kappaB and may occur through formation of transcriptionally inert multimeric complexes that are dependent upon the nature of the ERalpha ligand.

Phenotypic diversity and testosterone-induced normalization of mutant L712F androgen receptor function in a kindred with androgen insensitivity

Molecular causes of phenotypic diversity in androgen insensitivity syndrome, occurring even in the same family, have rarely been identified. We report on a family with four affected individuals, three brothers (B1-3) and their uncle, displaying strikingly different external genitalia: B1, ambiguous; B2, severe micropenis; B3, slight micropenis; and uncle, micropenis and penoscrotal hypospadias. All had been assigned a male gender. We detected the same L712F mutation of the androgen receptor (AR) gene in each subject. Methyltrienolone binding on cultured genital skin fibroblasts of B2 suggested moderate impairment of the ligand-binding domain [maximal binding capacity, 38.2 fmol/mg protein (normal); Kd, 0.21 nmol/L; normal range, 0.03-0.13 nmol/L]. In trans-activation assays, the mutant 712F-AR showed considerable deficiency at low concentrations of testosterone (0.01-0.1 nmol/L) or dihydrotestosterone (0.01 nmol/L). Remarkably, this could be fully neutralized by testosterone concentrations greater than 1.0 nmol/L. Hence, the 712F-AR could switch its function from subnormal to normal within the physiological concentration range of testosterone. This was reflected by an excellent response to testosterone therapy in B1, B2, and the uncle. Taking into account the well documented individual and time-dependent variation in testosterone concentration in early fetal development, our observations clearly illustrate the potential impact of varying ligand concentrations for distinct cases of phenotypic variability in androgen insensitivity syndrome.

Gonadotropin-releasing hormone receptor activation of extracellular signal-regulated kinase and tyrosine kinases in transfected GH3 cells and in alphaT3-1 cells

GH3 cells were stably transfected with the wild-type murine GnRH receptor and a clonal cell line selected on the basis of inositol phosphate production and PRL/GH release in response to GnRH. This cell line (wt28) was characterized by [125I]GnRH analog binding, [3H]inositol phosphate response to GnRH, and hormone secretion. We examined the activation of the mitogen-activated protein kinase isoforms, extracellular signal-regulated kinase 1/2 (ERK1/2) and tyrosine kinases in wt28 cells and alphaT3-1 cells (which express a native GnRH) using specific phospho-ERK1/2 and phosphotyrosine antibodies. Concentration-response and time-course data revealed that a sustained ERK1/2 response was seen only in aT3-1 cells. Furthermore, GnRH-induced tyrosine phosphorylation was detectable in alphaT3-1 cells, but not in wt28 cells. Activators for several different signaling pathways revealed distinct differences between the cell types. Protein kinase C activation by phorbol 12,13-dibutyrate was very effective in alphaT3-1 cells at phosphorylation of both ERK1/2 and tyrosine, whereas raising cAMP levels using forskolin also strongly increased wt28 cell ERK1/2 phosphorylation. Only the tyrosine phosphatase inhibitor pervanadate increased tyrosine phosphorylation in wt28 cells. The lack of sustained ERK1/2 phosphorylation in wt28 cells could be the result of minimal tyrosine kinase activation by GnRH compounded by a different pathway profile for ERK1/2 activation. When pervanadate and GnRH were combined, ERK1/2 phosphorylation was synergistic and sustained in wt28 cells, whereas the response was additive in alphaT3-1 cells. In sum, the intracellular pathways leading to ERK1/2 and tyrosine phosphorylation in alphaT3-1 and wt28 cells are distinct; thus, activating GnRH receptors in each of the two cell types leads to different sequelae of events regarding ERK1/2 activation.

The peroxisome proliferator perfluorodecanoic acid inhibits the peripheral-type benzodiazepine receptor (PBR) expression and hormone-stimulated mitochondrial cholesterol transport and steroid formation in Leydig cells

The peroxisome proliferator perfluordecanoic acid (PFDA) has been shown to exert an antiandrogenic effect in vivo by acting directly on the interstitial Leydig cells of the testis. The objective of this study was to examine the in vitro effects of PFDA and identify its site of action in steroidogenesis using as model systems the mouse tumor MA-10 and isolated rat Leydig cells. PFDA inhibited in a time- and dose-dependent manner the hCG-stimulated Leydig cell steroidogenesis. This effect was localized at the level of cholesterol transport into the mitochondria. PFDA did not affect either the total cell protein synthesis or the mitochondrial integrity. Moreover, it did not induce any DNA damage. Morphological studies indicated that PFDA induced lipid accumulation in the cells, probably due to the fact that cholesterol mobilized by hCG did not enter the mitochondria to be used for steroidogenesis. In search of the target of PFDA, we examined its effect on key regulatory mechanisms of steroidogenesis. PFDA did not affect the hCG-induced steroidogenic acute regulatory protein (StAR) levels. However, it was found to inhibit the mitochondrial peripheral-type benzodiazepine receptor (PBR) ligand binding capacity, 18-kDa protein, and messenger RNA (mRNA) levels. Further studies indicated that PFDA did not affect PBR transcription, but it rather accelerated PBR mRNA decay. Taken together, these data suggest that PFDA inhibits the Leydig cell steroidogenesis by affecting PBR mRNA stability, thus inhibiting PBR expression, cholesterol transport into the mitochondria, and the subsequent steroid formation. Moreover, this action of PFDA on PBR mRNA stability indicates a new mechanism of action of peroxisome proliferators distinct from the classic transcription-mediated regulation of target genes.

Gtx, an oligodendrocyte-specific homeodomain protein, has repressor activity

Myelin, a multilamellar membrane structure that facilitates nerve conduction, is synthesized in the central nervous system (CNS) by oligodendrocytes. Gtx, a member of the homeodomain family of transcriptional factors, is a candidate regulator of myelin gene expression, because it is uniquely expressed in myelinating oligodendrocytes in postnatal rodent brain. To analyze the regulatory activity of Gtx, we first identified the optimal Gtx-binding sequence using an in vitro DNA-binding assay. This sequence, (A/T)TTAATGA, contains a TAAT core and is similar, but not identical, to that of other homeodomain protein binding sites. When coexpressed in cultured cells along with a minimal promoter containing five tandem repeats of this optimal Gtx-binding sequence, Gtx demonstrated repressor activity, which was also present when Gtx was tethered to DNA by way of the strong GAL4 DNA-binding domain. Truncations of the GAL4-Gtx fusion identified a portable repressor domain within a relatively proline/alanine-rich region N-terminal to the Gtx homeodomain. Cotransfection of a Gtx expression vector into a variety of cell lines, including oligodendrocytes, along with constructs containing portions of the PLP, MBP, or Gtx promoters fused to a reporter gene, however, did not modulate transcription from any of these promoter constructs. These data support the notion that the oligodendrocyte-specific homeodomain protein Gtx can act as a transcriptional repressor. In addition, they suggest that interaction of Gtx with other, as yet undefined, transcriptional regulators modifies Gtx activity in oligodendrocytes.

Angiogenesis inhibition by transdominant mutant Ets-1

The expression of transcription factor Ets-1 is induced in endothelial cells (ECs) by angiogenic factor; and in turn Ets-1 converts ECs to angiogenic invasive phenotype. In order to control angiogenesis, we constructed a transdominant mutant Ets-1 (TMEts-1) which acts as a dominant negative molecule. This molecule inhibited the DNA binding and the transactivation activity of the wild-type Ets-1. Stable transfection of murine endothelial cell line MSS31 cells with the TMets-1 gene impaired angiogenic activities including proliferation, migration, invasion, and tube formation in type-1 collagen gel. Finally, we incorporated the TMets-1 gene into a non-proliferative adenovirus vector, designated as AdTMets-1. AdTMets-1 significantly inhibited angiogenesis in the Matrigel plugs injected into the subcutaneous tissue of C57BL mice. These results indicate that TMets-1 would be a tool for angiogenic inhibition.

Antisense inhibition of cyclin D1 in human head and neck squamous cell carcinoma

OBJECTIVE

To study the role of cyclin D1 in regulating the biological behavior of head and neck cancer.

DESIGN

Squamous cell carcinoma of the head and neck (SCCHN) cells were stably transfected with an antisense cyclin D1 using lipofectin-mediated transfection. In vitro growth assays, cell cycle analyses, cytotoxicity assays, and in vivo tumorigenicity assays were performed.

MATERIALS

Human SCCHN cell lines TU138, TU167, TU177, TU182, MDA183, and MDA1386 and athymic nude mice were used for this study.

RESULTS

The antisense cyclin D1 transfected cells revealed decreased growth rates in vitro and decreased tumorigenicity in athymic nude mice. Furthermore, antisense cyclin D1 transfection enhanced the chemosensitivity against cisplatin.

CONCLUSIONS

These studies provided evidence that overexpression of cyclin D1 may play an important role in growth rates and biological behavior of human head and neck cancer. Additionally, expression of cyclin D1 may make human head and neck cancer cells resistant to platinum-based chemotherapeutic approaches. The ability to suppress the malignant phenotype by down-regulating cyclin D1 expression may provide a new gene therapy approach for patients with head and neck cancer.

Quantitative fluorescence cytometric analysis of Bcl-2 levels in tumor cells exhibiting a wide range of inherent Bcl-2 protein expression: correlation with Western blot analysis

BACKGROUND

A protocol to measure a wide range of Bcl-2 protein expression using quantitative fluorescence cytometry (QFCM) in different cell types was developed for use with flow cytometry. Bcl-2 measurements obtained by flow cytometry were correlated with Western blot Bcl-2 measurements to confirm specificity of the Bcl-2-FITC staining. This protocol was applied to measure absolute levels of Bcl-2 protein in different tumor cell lines including Bcl-2-transfected breast carcinoma cell lines and in peripheral blood lymphocytes (PBL).

METHODS

HL-60, K562, DOHH2, Jurkat, MDA435/LCC6, MCF7 cell lines, and PBL derived from normal donors were fixed, permeabilized, stained with anti-Bcl-2-FITC antibody and evaluated by QFCM. In parallel, the same cells were evaluated for Bcl-2 protein expression by Western blot analysis. Mitochondrial localization of anti-Bcl-2-FITC antibody inside cells was confirmed using fluorescence imaging microscopy.

RESULTS

Bcl-2 expression in different cell types could be accurately quantified based on antibody-binding capacity (ABC) ranging from 12.6 x 10(3) antibody-binding sites in HL-60 cells to 1.64 x 10(6) antibody-binding sites in a Bcl-2-transfected MDA435/LCC6 clone. The data from flow cytometry analysis correlated well with Western analysis (R(2) = 0.78). Bcl-2-FITC staining colocalized with dyes specific for mitochondria.

CONCLUSIONS

The Bcl-2 staining protocol described here was shown to be specific, sensitive, and it was able to provide higher resolution as well as more reproducible quantitation of Bcl-2 protein content in cells when compared with Western blot methods. Quantitation of Bcl-2 content in cells by QFCM may be useful for monitoring Bcl-2 expression in cells undergoing various treatments in vitro and in vivo.

Antisense inhibition of vascular endothelial growth factor in human head and neck squamous cell carcinoma

BACKGROUND

Vascular endothelial growth factor (VEGF) is a potent paracrine angiogenic factor involved in angiogenesis. We determined whether antisense VEGF transfection can suppress angiogenic activity of a human squamous cell carcinoma of the head and neck (SCCHN) cell line.

METHODS

Human SCCHN cell lines were screened for VEGF secretion by ELISA. The highest VEGF secreting cell line was transfected with an antisense VEGF vector. Endothelial cell migration assays were performed using the conditioned medium from the transfected clones. Tumorigenicity assays of the transfectants in nude mice were also performed.

RESULTS

Antisense VEGF expression exhibited a 20-fold inhibition of VEGF secretion. The addition of conditioned medium from the antisense clones resulted in 50% reduction of endothelial migration. There was no effect on in vivo tumorigenicity.

CONCLUSIONS

Antisense VEGF transfection effectively down-regulated VEGF secretion from SCCHN cells that had high VEGF secretion. Targeting VEGF expression may be useful for suppressing angiogenesis in head and neck cancer.

Transfection efficiency increases by incorporating hydrophobic monomer units into polymeric gene carriers

The water soluble terpolymer, poly(N-isopropylacrylamide (IPAAm)-co-2-(dimethylamino)ethyl methacrylate (DMAEMA)-co-butylmethacrylate (BMA)) was synthesized, and its efficiency in in vitro gene transfection was evaluated. Copolymers with different compositions were synthesized by radical polymerization. For a series of copolymers containing 60 mol% of DMAEMA, the plasmid bands were retained within the gel loading slot, independent of polymer/plasmid weight ratios or BMA monomer content. In contrast, for a series of copolymers containing 20 mol% DMAEMA, plasmid bands of complexes were retarded with increasing weight ratios. For the copolymer with 10 mol% BMA content, the plasmid was completely retained within the gel loading slot. The transfection efficiency of polymer/plasmid complexes was evaluated in COS-1 cells using a pCMV-lacZ plasmid, encoding for beta-galactosidase as a reporter gene. Transfection efficiency of a series of copolymers containing 20 mol% of DMAEMA varied with BMA content. The transfection efficiency of the copolymers with 0, 2, and 5 mol% of BMA was low. The transfection efficiency of the copolymers with 10 mol% of BMA was about 2-fold higher than that of the PDMAEMA control homopolymer. The transfected cells were observed at a very wide range of polymer/plasmid weight ratios. The transfection efficiency of all copolymers containing 60 mol% of DMAEMA was lower than that of the PDMAEMA homopolymer.

Specific gene transfer mediated by galactosylated poly-L-lysine into hepatoma cells

Plasmid DNA/galactosylated poly-L-lysine(GalPLL) complex was used to transfer luciferase reporter gene in vitro into human hepatoma cells by a receptor-mediated endocytosis process. DNA was combined with galPLL via charge interaction (DNA:GalPLL:fusogenic peptide, 1:0.4:5, w/w/w) and the resulting complex was characterized by dynamic light scattering, gel retardation assay and zeta potential analyzer to determine the particle size, electrostatic charge interaction, and apparent surface charge. The complex was tested for the efficiency of gene transfer in cultured human hepatoblastoma cell line Hep G2 and fibroblast cells NIH/3T3 in vitro. The mean diameter of the complex (DNA:GalPLL=1:0.4, w/w) was 256+/-34.8 nm, and at this ratio, it was positively charged (zeta potential of this complex was 10.1 mV). Hep G2 cells, which express a galactose specific membrane lectin, were efficiently and selectively transfected with the RSV Luc/GalPLL complex in a sugar-dependent manner. NIH/3T3 cells, which do not express the galactose-specific membrane lectin, showed only a marginal level of gene expression. The transfection efficiency of GalPLL-conjugated DNA complex into Hep G2 cells was greatly enhanced in the presence of fusogenic peptide that can disrupt endosomes, where the GalPLL-DNA complex is entrapped with the fusogenic peptide. With the fusogenic peptide KALA, the luciferase activity in Hep G2 cells was ten-fold higher than that of cells transfected in the absence of the fusogenic peptide. Our gene transfer formulation may find potential application for the gene therapy of liver diseases.

Sustained elevation in inositol 1,4,5-trisphosphate results in inhibition of phosphatidylinositol transfer protein activity and chronic depletion of the agonist-sensitive phosphoinositide pool

The 43 kDa inositol polyphosphate 5-phosphatase (5-phosphatase) hydrolyses the signalling molecules inositol 1,4,5-trisphosphate (Ins(1,4,5)P(3)) and inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4, 5)P(4)) in a signal-terminating reaction. We have utilised cell lines that stably underexpress the 43 kDa 5-phosphatase, as a model system to investigate whether Ins(1,4,5)P(3) can control the rate of its own formation by regulating the resupply of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P(2)). A sustained 2.6-fold elevation in the basal concentration of Ins(1,4,5)P(3), in cell lines underexpressing the 43 kDa 5-phosphatase, correlated with a 32% reduction in the total cellular mass of PtdIns(4,5)P(2). The depletion in cellular PtdIns(4,5)P(2) was confined to a Triton-insoluble cell compartment, enriched in caveolin. In resting cells with elevated Ins(1,4,5)P(3) concentrations resulting from underexpression of the 43 kDa 5-phosphatase, phosphatidylinositol (PtdIns) and phosphatidylinositol 4-phosphate (PtdIns(4)P) were depleted by 50% and PtdIns(4,5)P(2) by 61% in the caveolin-enriched Triton-insoluble compartment. Agonist stimulation resulted in the rapid turnover of phosphoinositides in the caveolin-enriched Triton-insoluble fraction of vector-transfected cells, but not in cells with high basal Ins(1,4,5)P(3) concentrations. Depletion of phosphoinositides from the caveolin-enriched Triton-insoluble pool in cells underexpressing the 43 kDa 5-phosphatase did not result from activation of phospholipase C isoenzymes, or inhibition of PtdIns 4-kinase or PtdIns(4)P 5-kinase activities. Significant inhibition of phosphatidylinositol transfer protein (PITP) activity (up to 70%) was observed in cells with elevated basal Ins(1,4,5)P(3) concentrations; however, no reduction in PITP(α) protein expression was detected. These studies indicate that chronic elevation in cellular Ins(1,4,5)P(3) concentrations decreases the PITP-mediated resupply of phosphoinositides in the caveolin-enriched agonist-sensitive pool.

Protein kinase C(alpha) actively downregulates through caveolae-dependent traffic to an endosomal compartment

Receptor desensitization occurs through receptor internalization and targeting to endosomes, a prerequisite for sorting and degradation. Such trafficking processes may not be restricted to membrane associated receptors but may also play an important role in the downregulation of cytoplasmic transducers such as protein kinase C (PKC). It is demonstrated here that acute TPA exposure induces the transport of activated PKC(alpha) from the plasma membrane to endosomes. This process requires PKC activity and catalytically competent PKC can even promote a similar process for a truncated regulatory domain PKC(α) protein. It is established that PKC(α) is targeted to the endosome compartment as an active kinase, where it colocalizes with annexin I, a substrate of PKC. Thus, PKC(alpha) downregulation shares features with plasma membrane associated receptor sorting and degradation. However, it is shown that PKC(α) delivery to the endosome compartment is not a Rab5 mediated process in contrast to the well characterised internalisation of the transferrin receptor. An alternative route for PKC(alpha) is evidenced by the finding that the cholesterol binding drugs nystatin and filipin, known to inhibit caveolae mediated trafficking, are able to block PKC(alpha) traffic and down regulation. Consistent with this, the endosomes where PKC(alpha) is found also contain caveolin. It is concluded that the initial step in desensitisation of PKC(alpha) involves active delivery to endosomes via a caveolae mediated process.

Regulated expression of the rat recombinant P2X(3) receptor in stably transfected CHO-K1 tTA cells

In this report, the regulatable expression by tetracycline of the rat recombinant P2X(3) receptor in stably transfected Chinese hamster ovary (CHO-K1) expressing the tetracycline-controlled transactivator (tTA) is described. cDNA encoding the rat P2X(3)-receptor was subcloned into pTRE (a tetracycline-repressible expression vector) which was used to transfect stably CHO-K1 tTA cells. Using whole cell patch clamp techniques, 100 microM ATP evoked inward currents of 2.9+/-1.6 nA in transfected cells grown in the absence of tetracycline (tet-). The P2X(3) receptor protein was detectable by immunoblot as early as 24 h and protein expression levels continued to increase as much as 192 h following activation of tTA by the removal of the antibiotic. Saturation binding isotherms using [35S]ATP gamma S yielded a pK(d) of 8.2+/-0.1 and a B(max) of 31.9+/-3.5 pmol/mg protein in tet- cell membranes and a pK(d) of 8.1+/-0.1 and a B(max) of 5.8+/-0.8 pmol/mg protein in tet+ cell membranes. The agonist ligands 2MeSATP and alpha beta MeATP displaced the binding of [35S]ATP gamma S in tet- cell membranes with very high affinity, yielding pIC(50) values of 9.4+/-0.2 and 7.5+/-0. 2, respectively. In tet+ cell membrane, displacement of [35S]ATP gamma S by 2MeSATP and alpha beta MeATP was of much lower affinity (pIC(50) values of 7.8 and 6.2, respectively). ATP, ADP and UTP showed similar displacement of [35S]ATP gamma S binding in tet- and tet+ cell membranes. In other experiments, cytosolic Ca(2+) was monitored using the fluorescent indicator, fluo-3. Increases in cytosolic Ca(2+) were elicited by 100 nM alpha beta MeATP in tet- cells while no increases in cytosolic Ca(2+) were detected below 100 microM alpha beta MeATP in either tet+ cells or untransfected cells. These calcium responses to alpha beta MeATP had a pEC(50) of 6.7 and were transient, returning to baseline within 120 s. Suramin produced concentration-dependent, parallel, dextral shifts of E/[A] curves to alpha beta MeATP yielding a pK(B) of 5.6. PPADS produced non-parallel, dextral shifts of E/[A] curves to alpha beta MeATP which were insurmountable. These results show for the first time, expression of a functional, homomeric recombinant rat P2X(3) receptor which is under regulated expression in a stably transfected mammalian cell line.

Failure of membrane targeting causes the functional defect of two mutant sodium iodide symporters

Molecular cloning of the sodium/iodide symporter (NIS) allowed identification of NIS gene mutations in patients with iodide trapping defect. Whereas various mutant human (h) NIS molecules display loss of function when expressed by transfection in mammalian cells, the precise mechanism(s) responsible for the functional abnormality of these proteins remains unknown. With the aim to explore these mechanisms in three natural hNIS mutants identified previously in patients with iodide trapping defect (Q267E, S515X, and C272X), we have prepared tools allowing direct measurement of the protein at its normal location in the plasma membrane. A COS-7 cell line was made by transfection that stably expressed high levels of wild-type hNIS. It was used to screen by flow cytometry monoclonal antibodies (mAbs) prepared from mice immunized against hNIS. Genetic immunization was performed by im injection of a wild-type hNIS complementary DNA construct, because this procedure has demonstrated the ability to produce antibodies recognizing native membrane proteins. One mAb that recognized an epitope of hNIS exposed on the extracellular side of the plasma membrane was selected for further studies. The epitope was localized on the sixth putative extracellular loop of the protein on the basis that the mAb did not recognize rat NIS, which exhibits major sequence differences in this segment. When this mAb was used to test by flow cytometry the expression of the three mutant hNIS proteins in transfected COS-7 cells, it detected similar amounts of wild-type, Q267E, and the S515X hNIS molecules in permeabilized cells. In contrast, only the wild-type hNIS was detected at the surface of nonpermeabilized cells. The C272X hNIS truncation mutant was not detected in intact or permeabilized cells. This is consistent with the absence of the mAb epitope from this mutant, which is expected to lack the sixth extracellular loop. Our data demonstrate that faulty membrane targeting is implicated in the mechanisms causing iodide trapping defect in the Q267E and S515X natural hNIS mutants.

Identification of mutations causing 6-pyruvoyl-tetrahydropterin synthase deficiency in four Italian families

6-Pyruvoyl-tetrahydrobiopterin synthase (PTPS) is involved in tetrahydrobiopterin (BH4) biosynthesis, the cofactor for various enzymes including the hepatic phenylalanine hydroxylase. Inherited PTPS deficiency leads to BH4 depletion, causes hyperphenylalaninemia, and requires cofactor replacement therapy for treatment. We previously isolated the human PTPS cDNA and recently characterized its corresponding gene, PTS. Here we developed PCR-based mutation analysis with newly designed primers to detect genomic alterations and describe five mutations, four of which are novel, in the PTS gene of four Italian families with affected individuals. The mutant alleles found included three missense mutations (T67M, K129E, D136V), a previously described triplet deletion (delta V57), and a single c-3-->g transversion in the 3'-acceptor splice site of intron 1, leading to cryptic splice site usage that resulted in a 12 bp deletion (mutant allele delta (K29-S32)). Except for K129E, all mutant alleles were inactive and/or unstable proteins, as shown by recombinant expression and Western blot analysis of patients' fibroblasts. The PTPS-deficient patient with the homozygous K129E allele had transient hyperphenylalaninemia, did not depend on BH4 replacement therapy, and showed normal PTPS immunoreactivity, but no enzyme activity in primary fibroblasts and red blood cells. In contrast to its inactivity in these cells, the K129E mutant was 2-3 fold more active than wild-type PTPS when transfected into COS-1 or the human hepatoma cell line Hep G2. K129E appears thus as a mutant PTPS whose activity depends on the cell type.

Uncoiling c-Jun coiled coils: inhibitory effects of truncated Fos peptides on Jun dimerization and DNA binding in vitro

c-Jun is an oncoprotein that comprises a portion of the AP-1 transcription factor and belongs to the basic-leucine zipper (bZIP) DNA binding protein family. Using peptides derived from the leucine zipper region of Fos, we have developed agents that inhibit Jun's DNA binding in the low micromolar range. Fos peptides that were effective inhibitors in the DNA binding assay were also found to inhibit cellular Jun binding to an AP-1 site in a luciferase reporter plasmid in MCF-7 cells. Size exclusion studies confirmed that peptides that inhibit the DNA binding of Jun also inhibit its dimerization. These peptides were found to have a cytotoxic effect on the MCF-7 cell line when delivered with the transfecting agent Tfx-50, possibly due to their role as transcription factor regulators.

Oxidation, nitrosation, and nitration of serotonin by nitric oxide-derived nitrogen oxides: biological implications in the rat vascular system

Because NO is not very reactive in an oxygen-free buffer, a significant part of serotonin (5-HT) is transformed by NO in nondeaerated phosphate buffer, at pH 7.4, into (4-serotonyl)-4-serotonin, 4-nitrososerotonin, and 4-nitroserotonin. Dimerization and above all nitrosation occur through the HNO2 reaction in the pH 4-6 range, possibly via radical mechanism involving N2O3. 5-HT is readily a substrate for nitrosation by HNO2 or N2O3, whereas tyrosine was described as not very reactive under the same conditions. Peroxynitrite converts 5-HT to the (4-serotonyl)-4-serotonin and to the 4-nitro derivative. In order to evaluate whether such structural modifications could modulate the biological properties of 5-HT, arterial pressure was measured after i.v. bolus injection of these derivatives to anesthetized rats. Injections of the 4-nitroso- and 4-nitro-5-HT resulted in first a brief hypotensive response and did not give the subsequent hypertensive and hypotensive phases observed with 5-HT. Finally, when tested on some cloned rat 5-HT receptors stably transfected into LMTK- cells, both 4-nitroso and 4-nitro derivatives behaved as agonists and antagonists toward 5-HT1B and 5-HT2B receptors, respectively.

Molecular cloning of a truncated p62Dok1 isoform, p22Dok(del)

The p21Ras GTPase activating protein-associated 62-kDa protein, p62Dok1, is an early substrate of various tyrosine phosphorylation pathways. Its recent cloning in human myeloid cells and in murine pre-B cells revealed an N-terminal pleckstrin-homology domain and a tyrosine- and proline-rich C-terminal tail in its sequence. Here, we characterized a new 1261-bp cDNA identical to that of p62Dok1, but with a central 185-bp deletion (bp 456-640). This induced a frameshift leading to a premature stop codon. The deduced protein, designated p22Dok(del), corresponded to a truncated p62Dok1 isoform of 177 amino acids that can be expressed both in vitro and in vivo with an apparent molecular mass of 22 kDa. This newly identified molecule was composed of the N-terminal PH domain of p62Dok1 followed by a new 25-amino acid C-terminal sequence containing a typical class II proline-rich motif, suggesting a specific role for p22Dok(del) in signal transduction pathways.

Neurotrophin-3 sorts to the constitutive secretory pathway of hippocampal neurons and is diverted to the regulated secretory pathway by coexpression with brain-derived neurotrophic factor

Hippocampal neurons release nerve growth factor (NGF) through the constitutive secretory pathway, thus allowing the protein to be continuously available for promoting nerve cell survival. In contrast, hippocampal neurons use the regulated secretory pathway to process brain-derived neurotrophic factor (BDNF), which alters synaptic activity when released acutely from dense-core vesicles. Thus, understanding how neurons sort and deliver neurotrophins may provide clues to their functions in brain. In this study, we monitored the processing and delivery of neurotrophin-3 (NT-3). Pulse-chase studies, immunocytochemistry, and secretagogue-induced release experiments were performed on cultured hippocampal neurons and AtT-20 cells infected with vaccinia viruses encoding the NT-3 precursor (pro-NT-3). Results show that most newly synthesized NT-3 is released through the constitutive secretory pathway as a result of furin-mediated endoproteolytic cleavage of pro-NT-3 in the trans-Golgi network. Pro-NT-3 can also be diverted into the regulated secretory pathway when cells are treated with alpha1-PDX, a selective inhibitor of furin-like enzymes, or when pro-NT-3 expression is increased by transient transfection methods. In cells coinfected with viruses coding for pro-NT-3 and pro-BDNF, NT-3 is sorted into the regulated pathway, stored in secretory granules, and released in response to extracellular cues together with BDNF, apparently as a result of heterodimerization, as suggested by coimmunoprecipitation data. Taken together, these data show that sorting of the NT-3 precursor can occur in both the constitutive and regulated secretory pathways, which is consistent with NT-3 having both survival-promoting and synapse-altering functions.

The central nervous system convulsant pentylenetetrazole stimulates gamma-aminobutyric acid (GABA)-activated current in picrotoxin-resistant GABA(A) receptors in HEK293 cells

We tested the ability of the central nervous system convulsant pentylenetetrazole (PTZ) to inhibit gamma-aminobutyric acid (GABA)-gated current in receptors expressing a mutation that rendered them resistant to picrotoxin. Consistent with previous reports, receptors expressing beta2(T246F), along with alpha3 and gamma2 subunits, resulted in a greatly diminished sensitivity to picrotoxin. Sensitivity to PTZ was completely abolished in the mutant receptor, confirming the hypothesis that PTZ acts at the picrotoxin site. Quite unexpected, however, was our finding that PTZ elicited marked stimulation (up to 400% of control) in the mutated receptors. This stimulatory effect was not mediated via an interaction with the benzodiazepine site, as preincubation with the benzodiazepine antagonist flumazenil did not block the PTZ-induced stimulation. Our results reveal the existence of a novel stimulatory domain of PTZ in GABA(A) receptors.

Cloning of rabbit alpha(1b)-adrenoceptor and pharmacological comparison of alpha(1a)-, alpha(1b)- and alpha(1d)-adrenoceptors in rabbit

We have isolated a cDNA clone of the rabbit alpha(1b)-adrenoceptor which has an open reading frame of 1557 nucleotides encoding a protein of 518 amino acids. The sequence shows higher identity to those of hamster, human, and rat alpha(1b)-adrenoceptors than to those of rabbit alpha(1a)- and alpha(1d)-adrenoceptors. The pharmacological binding properties of this clone expressed in Cos-7 cells showed a characteristic profile as alpha(1b)-adrenoceptor; high affinity for prazosin (pK(i)=10.3), relatively high affinity for tamsulosin (9.5) and low affinity for (-)-(R)-1-(3-hydroxypropyl)-5-[2-[[2-[2-(2,2, 2-trifluoroethoxy)phenoxy]ethyl]amino]propyl]indoline-7-carboxamid e (KMD3213) (8.5), 2-(2,6-dimethoxy-phenoxyethyl)-aminomethyl-1, 4-benzodioxane hydrochloride (WB4101) (8.7), and 8-[2-[4-(2-methoxy-phenyl)-L-piperazinyl]-8-azaspiro[4,5]decane-7, 9-dione dihydrochloride (BMY7378) (7.3). We have compared the levels of mRNA expression of three alpha(1)-adrenoceptor subtypes in rabbit tissues using the competitive reverse transcription/polymerase chain reaction (RT/PCR) assay. In most rabbit tissues except heart, alpha(1a)-adrenoceptor mRNA was expressed 10 folds more than the other two subtypes. However, binding experiments with [3H]prazosin and [3H]KMD3213 in rabbit tissues revealed a poor relationship between binding density and mRNA level. Especially, alpha(1b) binding sites were exclusively predominant in spleen, whereas the alpha(1b) subtype was minor at the mRNA level. These results indicate a high identity of structural and pharmacological profiles of three distinct alpha(1)-adrenoceptor subtypes between rabbit and other species, but there are species differences in their distribution.

Antagonist activity of meta-chlorophenylpiperazine and partial agonist activity of 8-OH-DPAT at the 5-HT(7) receptor

This study compared the use of adapter G-proteins to link G(s) coupled G-protein receptors to a Ca(2+) signal, enabling high throughput functional studies using a fluorescent imaging plate reader (FLIPR, Molecular Devices). The pharmacological profile of the human 5-hydroxytryptamine (5-HT(7)) receptor was studied using the adapter G-proteins G(alpha16) and G(qs5) and compared to previously published adenylyl cyclase and receptor binding data. Human embryonic kidney (HEK) 293 cells stably expressing the human 5-HT(7(a)) receptor were transiently transfected with the adapter G-proteins. Changes in intracellular Ca(2+) were monitored using the fluorescent Ca(2+)-indicator Fluo-4.5-Carboxamidotryptamine (5-CT) induced an increase in fluorescence in transfected cells only, which was attenuated by N-ethylmalaeimide and abolished by thapsigargin, consistent with a G-protein mediated mobilisation of intracellular Ca(2+). The pharmacological profile of agonists at the 5-HT(7) receptor was similar using either adapter G-protein. Agonist potency estimates were similar to that reported in binding studies but were greater than that seen in adenylyl cyclase studies. 8-Hydroxy-N, N-dipropylaminotetralin (8-OH-DPAT) and tryptamine acted as partial agonists using the adapter G-proteins, but were full agonists in recombinant systems using adenylyl cyclase. meta-Chlorophenylpiperazine (mCPP) and trifluoro-methylphenyl piperazine (TFMPP) were antagonists on intracellular Ca(2+). Antagonist pharmacological profiles were similar between adapter G-proteins, receptor binding, and adenylyl cyclase studies. These results show that adapter G-proteins can be used to study G(s)-linked receptors using the high throughput FLIPR system measuring changes in intracellular Ca(2+) and provide novel information on mCPP and 8-OH-DPAT.

Altered regulation of the D(1) dopamine receptor in mutant Chinese hamster ovary cells deficient in cyclic AMP-dependent protein kinase activity

To investigate the role of the cAMP-dependent protein kinase (PKA) in the desensitization and down-regulation of the D(1) dopamine receptor, we stably expressed the rat cDNA for this receptor in mutant Chinese hamster ovary (CHO) cell lines deficient in PKA activity. The 10260 mutant CHO cell line has been characterized as expressing less than 10% of type I and type II PKA activities relative to the parental 10001 CHO cell line. The 10248 mutant CHO line lacks type II PKA activity and expresses a defective type I PKA. The transfected parental and mutant cell lines were found to express approximately 1 pmol/mg D(1) receptor binding activity (B(max)) as determined using [(3)H]SCH-23390 binding assays. All three cell lines demonstrated similar levels of dopamine-stimulated adenylyl cyclase activity. Pretreatment of all three CHO cells with dopamine resulted in desensitization of the adenylyl cyclase response, although the maximum desensitization was attenuated by 20 and 40% in the 10260 and 10248 cell lines, respectively. Dopamine also promoted, in a time- and dose-dependent fashion, a >90% down-regulation of D(1) receptors in the parental cell line but only a 50 and 30% decrease in the 10260 and 10248 cells, respectively. Similarly, treatment of the cells with the membrane-permeable cAMP analog 8-(4-chlorophenylthio)-cAMP induced functional desensitization and down-regulation of the D(1) receptor, although it was not as great as that observed with agonist pretreatment. As with the agonist pretreatments, the 8-(4-chlorophenylthio)-induced responses were attenuated in the mutant cells with the 10248 line exhibiting the least desensitization/down-regulation. Our results suggest that PKA significantly contributes to the desensitization and down-regulation of D(1) receptors in CHO cells and that type II PKA may be the more relevant isoform with respect to regulating D(1) receptor function.

Canine thyrotropin beta-subunit gene: cloning and expression in Escherichia coli, generation of monoclonal antibodies, and transient expression in the Chinese hamster ovary cells

The gene encoding the mature beta subunit of canine thyroid stimulating hormone (cTSH beta) was cloned, sequenced and expressed in Escherichia coli and in Chinese hamster ovary (CHO) cells, and monoclonal antibodies against the recombinant cTSH beta purified from E. coli were generated. The gene fragment that encodes mature TSH beta was cloned from the canine genomic DNA by direct polymerase chain reaction (PCR) using primers that were designed based on the consensus sequences from other species. The resulting 891 basepairs (bp) of genomic DNA consisted of two coding exons of the canine TSH beta gene and an intron of 450 bp. The two exons, which encode the mature cTSH beta subunit, was joined together by an overlap PCR and was expressed in E. coli as 6xHis-tagged protein. The purified recombinant cTSH beta with a molecular weight of about 15 kDa was recognized by the polyclonal antibodies prepared against the native canine TSH in Western blot. Monoclonal antibodies were raised against the purified cTSH beta and subsequently characterized. For transient expression in CHO cells that are permanently transfected with the bovine common alpha gene, a 60-oligonucleotide signal peptide coding sequence was added to the 5' end of the cTSH beta gene before it was cloned into the mammalian expression vector pRSV and used to transfect CHO cells. The medium from these transfected cells, presumably containing the bovine alpha and canine TSH beta in heterodimeric confirmation, exhibited TSH bioactivity as indicated by the stimulation of cAMP production in the cultured FRTL-5 thyrocytes.

Lumbar transplant of neurons genetically modified to secrete brain-derived neurotrophic factor attenuates allodynia and hyperalgesia after sciatic nerve constriction

Chronic delivery of anti-nociceptive molecules by means of cell grafts near the pain processing centers of the spinal cord is a newly developing technique for the treatment of neuropathic pain. The rat neuronal cell line, RN33B, derived from E13 rat brainstem raphe and immortalized with the SV40 temperature-sensitive allele of large T antigen (tsTag), was transfected with rat brain-derived neurotrophic factor cDNA (BDNF), and the BDNF-synthesizing cell line, 33BDNF.4, was isolated. The 33BDNF.4 cells synthesized mature BDNF protein at permissive temperature (33 degrees C), when the cells were proliferating, and during differentiation at non-permissive temperature (39 degrees C) in vitro. The bio-active BDNF protein was also secreted by the cells during both growth conditions, as measured by ELISA analysis of BDNF content and secretion. The bio-activity of the BDNF in 33BDNF.4 cell conditioned media was assessed by neurite outgrowth from E15 dorsal root ganglion (DRG) cultures. A control cell line, 33V1, transfected with the vector alone, did not synthesize or secrete any significant BDNF at either growth condition. Both cell lines were used as grafts in a model of chronic neuropathic pain induced by unilateral chronic constriction injury (CCI) of the sciatic nerve. Pain-related behaviors, including cold and tactile allodynia and thermal and tactile hyperalgesia, were evaluated after CCI in the affected hindpaw. When 33BDNF.4 and 33V1 cells were transplanted in the lumbar subarachnoid space of the spinal cord 1 week after CCI, they survived greater than 7 weeks on the pia mater around the spinal cord and the 33BDNF.4 cells continued to synthesize BDNF in vivo. Furthermore, the tactile and cold allodynia and tactile and thermal hyperalgesia induced by CCI was significantly reduced during the 2-7 week period after grafts of 33BDNF.4 cells. The maximal effect on chronic pain behaviors with the BDNF grafts occurred 2-3 weeks after transplant and the anti-nociceptive effects of the BDNF cell grafts was permanent. Transplants of the control 33V1 cells had no effect on the allodynia and hyperalgesia induced by CCI and these cells did not synthesize BDNF in vivo. These data suggest that a chronically applied, low local dose of BDNF supplied by transplanted cells near the spinal dorsal horn was able to reverse the development of chronic neuropathic pain following CCI. The use of neural cell lines that are able to deliver anti-nociceptive molecules, such as BDNF, in a model of chronic pain offers a novel approach to pain management and such 'biologic minipumps' can be developed for safe use in humans.

Rabbit pregnane X receptor is activated by rifampicin

Reverse transcriptase-polymerase chain reaction was used to amplify a partial cDNA from rabbit lung mRNA that shared 77% protein sequence identity with the mouse pregnane X receptor (PXR). Rapid amplification of cDNA ends from a rabbit kidney lambdaZAP expression library resulted in the isolation of overlapping cDNAs spanning the complete coding sequence. The deduced amino acid sequence of 411 residues exhibited 79% overall amino acid identity with human PXR and 77% identity with mouse PXR. Based on this protein sequence relationship and a similar degree of conservation exhibited by the mouse and human PXR orthologs, the cDNA appears to encode the rabbit PXR ortholog. 5'-rapid amplification of cDNA ends performed on an adaptor-ligated cDNA library from rabbit liver revealed the presence of an alternate mRNA, which differed at the 5'-terminus. RNase protection assays indicated that the alternate mRNA was expressed at >50-fold lower levels in rabbit kidney and liver. Rifampicin treatment of CV-1 cells cotransfected with a rabbit PXR expression plasmid and a luciferase reporter construct containing two copies of the DR3 enhancer from CYP3A23 produced a 6-fold induction of luciferase activity. In contrast, rat PXR was not responsive to this antibiotic under the same conditions. Pregnenolone 16alpha-carbonitrile was an efficacious activator of rat PXR, but failed to significantly activate rabbit PXR at equivalent concentrations. These results indicate that the ligand activation profile of rabbit PXR is distinct from rat PXR and more closely resembles that of human PXR. The rabbit PXR activation profile is consistent with the cytochrome P450 (P450) 3A6 induction profile in rabbits.

Missense point mutations of tau to segregate with FTDP-17 exhibit site-specific effects on microtubule structure in COS cells: a novel action of R406W mutation

Missense and splicing point mutations have been found in the tau gene in families with frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17). Of these mutations, we examined four exonic missense point mutations (G272V, P301L, V337M and R406W) in 3-repeat or 4-repeat tau isoform on the transfection experiment. The effects of two mutations (G272V or P301L) on microtubules were subtle whereas those of two other mutations (V337M or R406W) were dramatically significant when these two mutations were constructed into 3-repeat tau but not into 4-repeat tau. The R406W mutation induced an alternation of microtubules to form dotted or fragmented forms retaining colocalization of tau with tubulin whereas the V337M mutation predominantly disrupted microtubule networks and diminished colocalization of tau and tubulin. The effect of the mutations on microtubules were thus site-dependent and isoform-dependent. Tau with R406W mutation was found to be colocalized with tubulin without filamentous structures on confocal views, suggesting that the carboxyl region of tau played a different role from tubulin-binding domain on microtubule assemble. Another abnormal property was identified in tau with R406W mutation that failed to suffer phosphorylation. Thus, diverse effects of tau mutations on microtubules may explain the various clinicopathologies of FTDP-17 and related tauopathies.

A lipid carrier with a membrane active component and a small complex size are required for efficient cellular delivery of anti-sense phosphorothioate oligonucleotides

Anti-sense oligonucleotides are potential therapeutic agents that are used to block protein expression from mRNA. To assess the essential properties for an efficient cellular delivery system of phosphorothioate oligonucleotides (PS-ODNs), different cationic carriers were compared. The carriers were complexed with oligonucleotides at various +/- charge ratios in MES-Hepes buffer. Cationic polymers, polylysines (PLL, mean MWs 4000, 20000, 200000 kDa), polyethyleneimines (PEI, mean MWs 25 and 800 kDa) and fractured sixth-generation polyamidoamine dendrimer (PAMAM) were tested for ODN delivery into a D 407 cell line (human retinal pigment epithelial cells) with stably transfected luciferase gene. Anti-sense ODN was directed against the luciferase gene, and the anti-sense effect was determined using a luminometric method. Lipid-based vehicles included DOTAP, DOTAP/DOPE (1/1 by mol), DOTAP/Chol (1/1 by mol), DOTAP/DOPE/Chol (2/1/1 by mol), DOGS and Cytofectin GS/DOPE (2/1 by mol). Additionally a membrane-active peptide JTS-1 (NH(2) -GLFEALLELLESLWELLLEA-COOH) was added to the complexes containing DOTAP, PEI or PLL. In D 407 and CV-1 cells, the anti-sense effect was seen only with lipid-based carriers with a membrane-active component (DOPE or JTS-1). The polymeric systems were ineffective. The effect of the complexation medium was further studied on CV-1 cells. Complexes were prepared in either water, MES-Hepes buffer or cell growth medium (DMEM). Complexes prepared in water were generally most effective and the greater activity is probably due to the smaller complex size. Complex sizes differed greatly in buffer and DMEM, especially in the case of DOPE containing complexes. In conclusion, lipid carrier with a membrane active component and small complex size are required for an efficient cellular delivery of phosphorothioate oligonucleotides.

Regulation of the CYP3A4 gene by hydrocortisone and xenobiotics: role of the glucocorticoid and pregnane X receptors

The molecular mechanisms of regulation of the CYP3A4 gene have been examined in an in vitro reporter gene system, containing -1 kb of the CYP3A4 promoter, in a HepG2 cell line. This system allows for the separate and combined transfection of expression plasmids encoding the human glucocorticoid receptor (hGR) and the human pregnane X receptor (hPXR), and, therefore, the opportunity to assess the role of these receptors in the induction process. Hydrocortisone produces a dose-dependent increase in CYP3A4 activation, a response that is increased in the presence of either receptor. Moreover, transfection of the hPXR decreased the EC(50) for hydrocortisone-dependent induction by a factor of 3.3, a response that was not changed by simultaneous cotransfection of the hGR. In addition, the hydrocortisone dose-response curve falls within the physiological blood level concentration of this steroid, implicating a regulatory role for hydrocortisone in the basal level of CYP3A4 expression. Although the responses to dexamethasone and rifampicin were both increased by both receptors, dexamethasone activation of CYP3A4 was similar for both the hGR and the hPXR, whereas rifampicin-dependent activation favored the hPXR. We conclude that regulation of the CYP3A4 gene is receptor-dependent and that hydrocortisone may function as a regulator of basal expression via the hPXR and the hGR. The implications of this latter conclusion for possible regulatory interactions between hydrocortisone and xenobiotic inducers remain to be clarified.

Expression of antisense RNA to aldehyde dehydrogenase class-1 sensitizes tumor cells to 4-hydroperoxycyclophosphamide in vitro

Previous studies in this laboratory showed that the overexpression of human aldehyde dehydrogenase class-1 (ALDH-1) with a retroviral vector resulted in increased resistance to 4-hydroperoxycyclophosphamide (4-HC), an active metabolite of cyclophosphamide. The present study examined the effect of ALDH-1 antisense RNA expression on ALDH-1 activity and sensitivity to 4-HC toxicity. Three different ALDH-1 cDNAs were synthesized that are either missing the N terminus (N), C terminus (C), or both (NC) and subcloned into the BamHI cloning site of pLXSN retroviral vector in the antisense (AS) orientation (AS-N, AS-C, and AS-NC, respectively). It was demonstrated that the overexpression of each of the AS constructs in K562 leukemic cells and A549 lung cancer cells results in suppression of ALDH-1 mRNA and enzymatic activity. Furthermore, the AS-N and AS-NC were generally more effective than AS-C in reducing the ALDH-1 activity. Both K562 and A549 cells expressing the ALDH-1 AS became significantly more sensitive to 4-HC toxicity as demonstrated by clonogenic and liquid culture assays. The increase in 4-HC sensitivity was in correlation with the degree of suppression of ALDH-1 activity. Moreover, such increase in 4-HC sensitivity, especially with AS-N and AS-NC, was to a similar degree seen with the use of diethylaminobenzaldehyde, a specific inhibitor of ALDH-1. These results indicate that ALDH-1 expression and activity can be specifically and effectively suppressed by AS RNA and lead to increased sensitivity to 4-HC.

Neurokinin(3) receptors couple to the activation of neuronal nitric-oxide synthase in stably transfected Chinese hamster ovary cells

Several physiological effects induced by activation of neurokinin(3) (NK(3)) receptors are mediated by the production of nitric oxide (NO). We investigated the intracellular coupling of NK(3) receptors to NO synthase (NOS) using a Chinese hamster ovary cell line that was stably transfected with both the NK(3) receptor and type I (neuronal) NOS. NOS activity in the transfected cell line was assayed directly, by measuring the formation of L-citrulline, another product of NOS, as well as indirectly, by measuring the production of cGMP in cultured rat fetal lung fibroblasts (RFL-6 cells). MePhe(7)-neurokinin B (NKB) stimulation of L-[(3)H]citrulline production was concentration-dependent and yielded a two-site model for the concentration-response relationship. The production of L-citrulline in response to two other tachykinins, substance P or neurokinin A, revealed only a one-site nature of the response. The production of cGMP in response to MePhe(7)-NKB had an EC(50) value that corresponded to the high-potency component of MePhe(7)-NKB-induced production of L-[(3)H]citrulline. Agonist-induced calcium signaling was also concentration-dependent, and the acute increase in the production of cGMP by MePhe(7)-NKB (0.1 nM) was dependent on the release of calcium from intracellular stores. Results of this study provide the first direct evidence that NK(3) receptors couple to the generation of NO within the same cell.

Endogenous TGF-beta1 inhibits the growth and metastatic dissemination of rat oral carcinoma cell lines but enhances local bone resorption

This study examined the effect of stable transfection of latent transforming growth factor-beta1 (TGF-beta1) cDNA into a predominantly polygonal, 4 nitroquinoline N-oxide (4NQO)-induced rat oral keratinocyte cell line. Seven polygonal and five spindle clonal populations were isolated that overexpressed TGF-beta1 protein by approximately two- to four-fold compared to vector-only transfected controls. Neutralisation experiments indicated that the majority of protein was in the latent form. There was no change in the proportion of polygonal and spindle cells in vitro after transfection with TGF-beta1 cDNA. Polygonal and spindle cells that overexpressed TGF-beta1 produced similar amounts of protein and grew more slowly in vitro than controls. The parent cell line and all transfected cells were growth inhibited (60-75%) by exogenous TGF-beta1. Orthotopic transplantation of the parent and the vector-only control cell lines resulted in primary tumours in the floor of the mouth in almost 100% (20/21) of athymic mice, with no evidence of bone resorption at the site of the primary tumour and pulmonary metastatic tumour deposits in some 40% (7/20) of these animals. The polygonal and spindle cells that overexpressed TGF-beta1 behaved similarly following orthotopic transplantation. A 96% (23/24) primary tumour take was evident following transplantation of cells that overexpressed TGF-beta1, with a significantly (P<0.02) higher number of animals showing bone resorption at the site of the primary tumour (35%; 8/23) compared to controls. By contrast, there was a significant (P<0.03) decrease in the number of animals with pulmonary metastases (4%; 1/23) following transplantation of TGF-beta1 overexpressing cells compared to controls. Overexpression of TGF-beta1 did not alter tumour cell differentiation in vivo. The results demonstrate that endogenous TGF-beta1 functions as a tumour suppressor in the rat-4NQO model of oral carcinogenesis without altering tumour cell morphology or differentiation but can also act to promote local bone resorption.

Differential modulatory actions of the volatile convulsant flurothyl and its anesthetic isomer at inhibitory ligand-gated ion channels

A challenge for theories of general anesthesia is the existence of compounds predicted to be anesthetics but which, instead, do not produce anesthesia and often elicit other behavioral effects such as convulsions. This study focused on flurothyl (bis[2,2, 2-trifluoroethyl] ether), a potent volatile convulsant, and its anesthetic isomer, 'iso-flurothyl' (1,1,1,3,3, 3-hexafluoro-2-methoxypropane). The effects of flurothyl and iso-flurothyl were studied using the whole-cell patch-clamp technique on agonist-activated chloride currents in human GABA(A), glycine, and GABA(C) rho(1) receptors expressed in HEK 293 cells. GABA(A) and glycine receptors are promising molecular targets for the actions of inhaled ether general anesthetics. Flurothyl acted as a non-competitive antagonist at GABA(A) alpha(2)beta(1) and alpha(2)beta(1)gamma(2s) receptors, but had no effect at glycine alpha(1) receptors. Flurothyl had biphasic actions on GABA responses at GABA(C) rho(1) receptors. In contrast, iso-flurothyl enhanced ('potentiated') submaximal agonist responses at GABA(A) and glycine receptors, but had no effect on GABA responses at GABA(C) rho(1) receptors. Point mutations in GABA(A) and glycine receptor subunits, which have been previously shown to abolish potentiation of agonist responses by the ether anesthetics enflurane and isoflurane, also ablated potentiation of agonist responses by iso-flurothyl. These same mutations in the GABA(A) receptor had only modest effects on the inhibitory actions of flurothyl. GABA(A) receptors with mutations conferring insensitivity to antagonism by picrotoxin were still inhibited by flurothyl, suggesting that picrotoxin and flurothyl antagonize GABA responses by distinct sites or mechanisms of action. In summary, antagonism of GABA(A) receptors is likely to account for the convulsant effects of flurothyl, while the general anesthetic actions of iso-flurothyl, like those of other ether anesthetics, may be related to positive modulation of GABA(A) and/or glycine receptors.

Isolation of current components and partial reaction cycles in the glial glutamate transporter EAAT2

The kinetic properties of the excitatory amino acid transporter EAAT2 were studied using rapid applications of L-glutamate to outside-out patches excised from transfected human embryonic kidney 293 cells. In the presence of the highly permeant anion SCN(-), pulses of glutamate rapidly activated transient anion channel currents mediated by the transporter. In the presence of the impermeant anion gluconate, glutamate pulses activated smaller currents predicted to result from stoichiometric flux of cotransported ions. Both anion and stoichiometric currents displayed similar kinetics, suggesting that anion channel gating and stoichiometric charge movements are linked to early transitions in the transport cycle. Transporter-mediated anion currents were recorded with ion and glutamate gradients favoring either unidirectional influx or exchange. Analysis of deactivation and recovery kinetics in these two conditions suggests that, after binding, translocation of substrate is more likely than unbinding under physiological conditions. The kinetic properties of EAAT2, the dominant glutamate transporter in brain astrocytes, distinguish it as an efficient sink for synaptically released glutamate.

Phylogenetic sequence analysis, recombinant expression, and tissue distribution of a channel catfish estrogen receptor beta

An estrogen receptor beta (ERbeta) cDNA fragment was amplified by RT-PCR of total RNA extracted from liver and ovary of immature channel catfish. This cDNA fragment was used to screen an ovarian cDNA library made from an immature female fish. A clone was obtained that contained an open reading frame encoding a 575-amino-acid protein with a deduced molecular weight of 63.9 kDa. Maximum parsimony and Neighbor Joining analyses were used to generate a phylogenetic classification of channel catfish ERbeta on the basis of 25 full-length teleost and tetrapod ER sequences. The consensus tree obtained indicated the existence of two major vertebrate ER subtypes, alpha and beta. Within each subtype, and in accordance with established phylogenetic relationships, teleost and tetrapod ER were monophyletic confirming the results of a previous analysis (Z. Xia et al., 1999, Gen. Comp. Endocrinol. 113, 360-368). Extracts of COS-7 cells transfected with channel catfish ERbeta cDNA bound estrogen with high affinity (K(d) = 0.21 nM) and specificity. The affinity of channel catfish ERbeta for estrogen was higher than previously reported for channel catfish ERalpha. As determined by qualitative RT-PCR, the tissue distributions of ERalpha and ERbeta were similar but not identical. Both ER subtypes were present in ovary and testis. ERalpha was found in all other tissues examined from juvenile and mature fish of both sexes. ERbeta was also found in most tissues except, in most cases, whole blood and head kidney. Interestingly, the pattern of expression of ER subtypes in head kidney always corresponded to the pattern in whole blood. In conclusion, we isolated a channel catfish ERbeta with ligand-binding affinity and tissue expression patterns different from ERalpha. Also, we confirmed the validity of our previously proposed general classification scheme for vertebrate ER into alpha and beta subtypes and within each subtype, into teleost and tetrapod clades.

Epitope-tagged insulin-like growth factor-I expression in muscle

Development of a recombinant insulin like growth factor I (IGF-I) that is distinguishable from its endogenous counterpart would provide a powerful tool for delineating the role of IGF in myogenesis. Therefore, the objective of this study was to create an epitope-tagged IGF-I that retains biological activity and determine whether expression of this construct is possible in muscle tissue following direct DNA injection. Expression vectors were created that encoded porcine IGF-I containing a T7 (11-amino acid) epitope-tag (TIGF). Immunoreactivity of the purified recombinant TIGF was confirmed using monoclonal antibodies. Biological activity was evaluated by examining differentiation of myoblasts cultured with TIGF or transfected with TIGF plasmid DNA. Addition of purified TIGF to myoblast cultures stimulated (P < 0.05) muscle creatine kinase levels similar to insulin (10(-5) M). Likewise, transfection of L6A1 with TIGF DNA hastened (P < 0.01) differentiation compared to control pcDNA-transfected myoblasts. The integrity of the recombinant protein was confirmed using a sandwich-configured enzyme linked immunosorbent assay. Finally, recombinant TIGF DNA was injected in porcine muscle and the ability to detect TIGF protein was evaluated. TIGF expression was detected in muscle fibers of injected porcine muscle. These data show that a T7 amino acid tag placed on the amino terminus of the IGF-I protein remains intact during processing and does not interfere with the biological activity of the molecule. Use of this DNA construct is an excellent tool for investigating the role of IGFs in control muscle development and provides a model to investigate other regulators of animal growth.

In vitro biotransformation of sildenafil (Viagra): identification of human cytochromes and potential drug interactions

The in vitro biotransformation of sildenafil to its major circulating metabolite, UK-103,320, was studied in human liver microsomes and in microsomes containing heterologously expressed human cytochromes. In human liver microsomes, the mean K(m) (+/-S.E. ) was 14.4 +/- 2.0 microM. A screen of the chemical inhibitors omeprazole (10 microM), quinidine (10 microM), sulfaphenazole (10 microM), and ketoconazole (2.5 microM) only revealed detectable inhibition with ketoconazole. Sildenafil biotransformation (36 microM) was inhibited by increasing concentrations of ketoconazole and ritonavir (IC(50) values less than 0.02 microM), which are established cytochrome P450 (CYP) 3A4 inhibitors. Using microsomes containing cDNA-expressed cytochromes, UK-103,320 formation was found to be mediated by four cytochromes: CYP3A4, -2C9, -2C19, and -2D6. Estimated relative contributions to net intrinsic clearance were 79% for CYP3A4 and 20% for CYP2C9; for CYP2C19 and -2D6, estimated contributions were less than 2%. These results demonstrate that CYP3A4 is the primary cytochrome mediating UK-103,320 formation and that drugs that inhibit CYP3A4 are likely to impair sildenafil biotransformation.

Thyroid hormone-induced stimulation of the sarcoplasmic reticulum Ca(2+) ATPase gene is inhibited by LIF and IL-6

We investigated the effects of the leukemia inhibitory factor (LIF) and interleukin-6 (IL-6) on 3,3', 5-triiodo-L-thyronine, or thyroid hormone (T(3))-stimulated sarcoplasmic reticulum Ca(2+) ATPase (SERCA2) gene expression on cultured neonatal rat cardiac myocytes. A reduction of T(3) induced increases in SERCA2 mRNA levels after co-treatment with LIF or IL-6. To investigate for the molecular mechanism(s) responsible for the blunted gene expression, a 3.2-kb SERCA2 promoter construct containing a reporter gene was transfected into cardiac myocytes. T(3) treatment stimulated transcriptional activity twofold, whereas co-treatment with T(3) and either of the cytokines caused an inhibition of T(3)-induced SERCA2 transcriptional activity. A T(3)-responsive 0.6-kb SERCA2 construct also showed a similar inhibition by cytokines. Cytokine inhibition of SERCA2 transcriptional activity was also evident when a 0.6-kb SERCA2 mutant, T(3)-unresponsive promoter construct was used. Treatment with T(3) and cytokines showed a significant decrease in transcription when a reporter construct was used that was comprised of direct repeats of SERCA2 thyroid response element I. These data provide evidence for cytokine-mediated inhibitory effects on the SERCA2 promoter that may be mediated by interfering with T(3) action.

Antisense-mediated inhibition of the bcl-2 gene induces apoptosis in human malignant glioma

BACKGROUND

The bcl-2 protooncogene represses a number of cellular apoptotic pathways and is known to be expressed in increasing amounts in glial tumors of higher malignancy. We tested whether antisense oligonucleotides to the bcl-2 gene would affect glioma cell viability.

METHODS

Antisense oligonucleotides directed to the first six codons of the human bcl-2 gene, and nonsense oligonucleotides as a control, were transfected into malignant glioma cells. Two human Bcl-2 positive glioblastoma cell lines from our tumor bank (Jon52 and Roc) were both transfected in vitro with bcl-2 antisense (AS) and nonsense (NS) oligonucleotides at 1 microm and 5 microm concentrations for 5 and 24 hr. Cell viability was assessed at 2, 4, 5, and 7 days by using an MTT mitogenic assay and by cell counting via direct visualization using a hemocytometer.

RESULTS

There was up to a log-fold decrease in cell growth of the bcl-2 AS treated cells compared to the NS transfected cells for both Roc (p = 0.007 and p = 0.004) and Jon52 (p = 0.02 and p = 0.004) at 5 and 24 hr of transfection. There was as much as 50% cytotoxicity in both glioblastoma cell lines at 1 microm and 5 microm concentrations after 24 hr transfection with AS bcl-2 oligonucleotides (all p < 0.01). Western blot analysis demonstrated a decrease in the expression of the Bcl-2 protein in one cell line, whereas there was a statistically significant increase in the apoptotic index of both cell lines (p < 0.05 by chi square analysis).

CONCLUSIONS

Our results suggest that transfection of human glioma cells with antisense bcl-2 results in an increase in apoptotic death. This provides evidence that Bcl-2 plays a role in tumor progression of glioma by acting as an oncogene, and suggests that inhibition of the bcl-2 gene could have a therapeutic effect.

Antiviral properties of a series of 1,6-naphthyridine and 7, 8-dihydroisoquinoline derivatives exhibiting potent activity against human cytomegalovirus

A series of 1,6-naphthyridine (L. Chan, H. Jin, T. Stefanac, J. F. Lavallee, G. Falardeau, W. Wang, J. Bedard, S. May, and L. Yuen, J. Med. Chem. 42:3023-3025, 1999) and isoquinoline (L. Chan, H. Jin, T. Stefanac, W. Wang, J. F. Lavallee, J. Bedard, and S. May, Bioorg. Med. Chem. Lett. 9:2583-2586, 1999) analogues exhibiting a high level of anti-human cytomegalovirus (HCMV) activity were investigated in a series of studies aimed at better understanding the mechanism of action of some representatives of this class of compounds. In vitro antiviral profiling revealed that these compounds were active against a narrow spectrum of viruses, essentially the human herpesviruses and type 2 rhinovirus. In HCMV assays, a 39- to 223-fold lower 50% inhibitory concentration was obtained for compound A1 than for ganciclovir against strains AD 169 and Towne. In addition, ganciclovir, foscarnet, cidofovir, and BDCRB (2-bromo-5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole)-resistant HCMV strains remained susceptible to 1,6-naphthyridines and 7, 8-dihydroisoquinolines tested in this study, supporting the view that a novel mechanism of action could be involved. Drug combination studies showed a small but significant synergistic antiviral effect between compound B2 and ganciclovir. Cytotoxicity profiling of representative compounds under various cell growth conditions indicated a generally similar cytotoxic effect, relative to ganciclovir, in log-phase growing cells. However, in stationary cells, a relatively higher level of toxicity was observed than that for control compound. Effect of time of drug addition showed that the anti-HCMV activity of compound A1, ganciclovir, and cidofovir was lost at approximately the same time (72 h postinfection), indicating that the compound was affecting events at the early and late stage of virus replication. This interpretation is also supported by reduction of de novo synthesis of pp65 tegument protein and lack of any effect of the compound on viral adsorption. A reduction of the HCMV enhancer-promoter-directed luciferase expression was also observed in a stably transfected cell line when compound A1 was present at relatively high concentrations.

Metallothioneins attenuate methylmercury-induced neurotoxicity in cultured astrocytes and astrocytoma cells

Metallothionein-I (MT-I) was expressed in neonatal rat primary astrocyte cultures and an astrocytoma cell line by pGFAP-MT-I plasmid transfection under the control of the astrocyte-specific glial fibrillary acidic protein (GFAP) promoter. Following transient transfection of the pGFAP-MT-I plasmid, MT-I mRNA and MT-I protein levels were determined by Northern blot and immunoprecipitation analyses, respectively. The ability of cells overexpressing MT-I to withstand acute methylmercury (MeHg) treatment was measured by the release of preloaded Na2(51)CrO4, an indicator of membrane integrity. Transfection with the pGFAP-MT-I plasmid led to increased mRNA (2.5-fold in astrocytes and 7.4-fold in astrocytomas) and MT-I protein (2.4-fold in astrocytes and 4.0-fold in astrocytomas) levels compared with their respective controls. Increased expression of MT-I was associated with attenuated release of Na2(51)CrO4 upon MeHg (5 microM) treatment. These results demonstrate that MT-I can be highly expressed both in primary astrocyte cultures and astrocytomas by pGFAP-MT-I plasmid transfection, and lend credence to the hypothesis that increased expression of MT-I affords protection against the cytotoxic effects of MeHg. Taken together, the data suggest that MTs offer effective cellular adaptation of MeHg cytotoxicity.

Angiogenesis induced by hepatocyte growth factor in non-infarcted myocardium and infarcted myocardium: up-regulation of essential transcription factor for angiogenesis, ets

The feasibility of a novel therapeutic strategy using angiogenic growth factors to expedite and/or augment collateral artery development has recently entered the realm of treatment of ischemic diseases. Hepatocyte growth factor (HGF) is a novel member of endothelium-specific growth factors whose mitogenic activity on endothelial cells is very potent. Although it has been demonstrated that HGF is a potential angiogenic growth factor in in vitro culture systems, there is no direct in vivo evidence for the angiogenic activity of HGF in physiological conditions. In this study, we hypothesized that transfection of HGF gene into infarcted myocardium could induce angiogenesis, potentially resulting in a beneficial response to hypoxia. Human HGF gene or control vector driven by the SRalpha promoter was transfected into rat myocardium by the HVJ-liposome method. Four days after in vivo transfection of human HGF gene, there was a marked increase in human immunoreactive HGF as compared with control vector (P < 0.01). In myocardium transfected with HGF vector, a significant increase in PCNA-positive endothelial cells was observed, while few PCNA-positive endothelial cells were detected in both control-vector-transfected and untreated myocardium. The number of vessels around the HGF injection sites was significantly increased as compared with control vector or vehicle (P < 0.01). Angiogenic activity induced by the transfection of HGF vector was also confirmed by the activation of a transcription factor, ets, which is essential for angiogenesis. Furthermore, we studied the pathophysiological role of HGF in a myocardial infarction model. The concentration of endogenous HGF was significantly decreased in infarcted myocardium. Therefore, we hypothesized that transfection of HGF gene into infarcted myocardium could induce a beneficial response to the decreased endogenous HGF. Indeed, transfection of human HGF into infarcted myocardium also resulted in a significant increase in the number of vessels (P < 0. 01), accompanied by marked induction of ets binding activity and a significant increase in blood flow. Overall, the present results provide direct in vivo evidence for the induction of angiogenesis by transfection of the human HGF gene in rat non-infarcted and infarcted myocardium. The constant production of local HGF resulting from the transgene may be considered as an innovative therapeutic angiogenesis strategy for ischemic diseases such as myocardial infarction. Gene Therapy (2000) 7, 417-427.