Up-regulation of γ-aminobutyric acid transporter I mediates ethanol sensitivity in mice

Ethanol is among the most widely abused drugs in the world. Chronic ethanol consumption leads to ethanol tolerance and addiction, and impairs learning and memory. Na+/Cl- dependent GABA transporters play an important role in controlling the concentration of GABA in the synaptic cleft, and thus they control the intensity and duration of synaptic transmission of GABA. It has been suggested that GABAergic system is involved in ethanol consumption, tolerance and addiction, because chronic ethanol consumption alters the expression of GABAA receptors and drugs on GABA receptors affect ethanol actions. The results of the present study reveal that that activity of GABA transporters in mouse brain after 15-min acute ethanol injection or after chronic ethanol consumption is increased. Moreover, mice pre-injected with a competitive or a noncompetitive antagonist of gamma-aminobutyric acid transporter subtype 1 (GAT1) showed high sensitivity to the sedative/hypnotic effects of ethanol. In contrast, transgenic mice overexpressing GAT1 displayed low sensitivity to ethanol, as shown by the righting reflex test. Mice overexpressing GAT1 survived a lethal dose of ethanol (9 g/kg, i.p.) longer, maintained locomotor activity longer after a sub-lethal dose (1.75 g/kg, i.p.) and exhibited a higher median lethal dose than wild-type littermates. These results suggest that GAT1 plays an important role in sensitivity to ethanol, and might be a therapeutic target for alcoholism prevention and treatment. Acute and chronic ethanol administration resulted in the increase of GABA transporter function. Use of GAT1 selective inhibitors and GAT1 overexpressing mice thus demonstrate that GAT1 should be an important protein mediating sensitivity to ethanol in mice.

Effect of Cr Addition on the Methane Aromatization Performance of the Mo/HZSM-5 Catalyst

The promotional effect of Cr addition on the methane aromatization performance of the Mo/HZSM-5 catalyst was investigated. It was found that much higher methane conversion was obtained over Mo–Cr/HZSM-5 catalyst than over Mo/HZSM-5. The results indicate that when the Cr/Mo molar ratio is 0.07, the methane conversion and aromatics selectivity reach 11.6 and 97.3% respectively at a reaction temperature of 973 K. Raising the temperature is beneficial to the methane conversion and 15.82% conversion is obtained at 1023 K. Modern measurements such as isopropyl alcohol decomposition and temperature desorption of ammonia (NH3-TPD) were used to characterized the catalysts. The results of isopropyl alcohol decomposition show that the surface acidity of Mo–Cr/HZSM-5 is increased at high temperature. The NH3-TPD findings imply that the Mo–Cr/HZSM-5 catalyst has much stronger acidity and more acid sites than Mo/HZSM-5, most likely one of the reasons for the enhanced activity for methane aromatization using Mo–Cr/HZSM-5 catalyst.

Norepinephrine transporter (NET) is expressed in cardiac sympathetic ganglia of adult rat

The sympathetic nervous system plays a cardinal role in regulating cardiac function through releasing the neurotransmitter norepinephrine (NE). In comparison with central nervous system, the molecular mechanism of NE uptake in myocardium is not clear. In present study, we proved that in rat the CNS type of NE transporter (NET) was also expressed in middle cervical-stellate ganglion complex (MC-SG complex) which is considered to control the activity of heart, but not expressed in myocardium. The results also showed that NET expression level in right ganglion was significantly higher than in the left, rendering the greater capacity of NE uptake in right ventricle, a fact which may contribute to the maintenance of right ventricular function under pathologic state.

A novel mechanism of dopamine neurotoxicity involving the peripheral extracellular and the plasma membrane dopamine transporter

Chinese hamster ovary cells stably expressing a rat dopamine transporter (designated D8 cells) and neuroblastoma SK-N-SH cells were used as two model systems to study dopamine neurotoxicity. Within 24 h, 1-10 mM dopamine induced D8 cells into apoptosis while 20-200 microM dopamine induced SK-N-SH cells into cell death. The viability of both cell types decreased in a dose-dependent manner. However, the dopamine uptake activity of D8 cells at 10 mM was not significantly higher than the uptake at 100 microM, suggesting that it was not the high concentration of intracellular dopamine that induced D8 cells into apoptosis, but rather dopamine found in the extracellular space. Furthermore, cocaine, an inhibitor of dopamine uptake, could not block cell death induced by dopamine. Forskolin, an agonist of protein kinase A (PKA), stimulated dopamine uptake in D8 cells and blocked apoptosis induced by the drug. These results suggest that the dopamine transporter mediates a dopamine-dependant apoptotic signal transduction pathway that is independent of dopamine uptake into the cell.

Genetic modification of hematopoietic progenitor cells for combined resistance to 4-hydroperoxycyclophosphamide, vincristine, and daunorubicin

AIM

To investigate whether human peripheral blood hematopoietic progenitor cells (PBPC) modified with human aldehyde dehydrogenase class-3 gene (ALDH-3) and multidrug resistance gene 1 (MDR1) would increase chemotherapy resistance to 4-hydroperoxycyclophosphamide (4-HC) and -glycoprotein effluxed drugs.

METHODS

A bicistronic retroviral vector G1Na-ALDH3-IRES-MDR1 cDNA was constructed and used to transfect the packaging cell lines PA317 by electroporation. CD34+ PBPC were isolated with a high-gradient magnetic cell sorting system (MACS), and then were transfected with supernatant of retrovirus containing human ALDH-3 and MDR1 cDNA. PCR, RT-PCR, Southern blot, Northern blot, FACS, and MTT assay were used to evaluate the transfection and expression of the transgene in target cells.

RESULTS

The bicistronic retroviral vector construction was verified by PCR and restriction endonuclease analysis. Dual drug resistance genes were integrated into the genomic DNA of CD34+ PBPC and expressed efficiently. The efficiency of gene transfection in CD34+ PBPC was tested to be 18 % on colonies. Nested PCR and Neor rescue assay indicated that no helper virus was present in this system. Compared with the untransduced cells, transgene recipient cells conferred 4.5-fold resistance to 4-HC, 6.6-fold and 7.8-fold resistance to P-glycoprotein effluxed drug, vincristine and daunorubicin, respectively.

CONCLUSION

Efficient transduction of two different types of drug resistance genes into human peripheral blood hematopoietic progenitor cells and the co-expression may decrease cumulative myelosuppression of combination chemotherapy.

Peptide derived from insulin with regulatory activity of dopamine transporter

A nonapeptide derived from the C terminus of the insulin B chain, H(2)N-Arg-Gly-Phe-Phe-Tyr-Thr-Pro-Lys-Ala-COOH, was found to strongly inhibit dopamine (DA) uptake by rat dopamine transporter (DAT) stably expressed in CHO cells (designated D8 cells). The kinetic experiments on D8 cells gave a curve typical of competitive inhibition with an IC(50)=6.9 microM. This inhibitory effect was also confirmed by experiments on striatal synaptosomes. The rat administered with the nonapeptide unilaterally into substantia nigra showed dose-dependent velocity and duration of the round movement contralateral to the nonapeptide-injected side. In addition, the nonapeptide dose-dependently reduced the binding of the tritium-labeled cocaine analog (-)-2 beta-carbomethoxy-3 beta-(4-fluorophenyl)tropane (WIN35,428) to DAT of D8 cells, which suggests that the nonapeptide may inhibit the transport activity of DAT in the way as cocaine does. Meanwhile, the peptide DOI (insulin with 8 amino acid residues deleted at the C terminus of the B chain) shows a significantly stimulating effect on DAT uptake activity in D8 cells. So insulin is proposed as a kind of neuropeptide precursor in the brain and insulin-derived peptides may be involved in the process of regulating the DA system, and these peptides may be developed into new medicines for disorders concerning the DA system such as Parkinson's disease and cocaine addiction.

[A bicistronic retroviral vector containing MGMT and MDR1 drug resistance genes transfer into human umbilical cord blood CD34+ cells to improve combination chemotherapy tolerance]

To explore whether human umbilical cord blood hematopoietic progenitor cells transduced with human O6-methylguanine-DNA-methyltransferase (MGMT) and multidrug resistance gene (MDR1) increase resistance to 1,3-Bis(2-Chloroethy1)-1-Nitrosourea (BCNU) and P-glycoprotein effluxed drugs, the present authors obtained a full length cDNA fragment encoding MGMT from liver tissue of a patient with cholelithiasis by RT-PCR. A bicistronic retroviral vector G1Na-MGMT-IRES-MDR1 cDNA was constructed and transfected the packaging cell lines GP + E86 and PA317 by electric performation method, using the medium containing VCR and BCNU for cloning selection and ping-ponging supernatant infection between ecotropic producer clone and amphotropic producer clone, cord blood CD34+ cells were enriched with a high-gradient magnetic cell sorting system (MACS), and then transfected repeatedly with supernatant of retrovirus containing human MGMT and MDR1cDNA under stimulation of hemapoietic growth factors. PCR, RT-PCR, Southern blot, Northern blot, Western blot, FACS and MTT assay were used to evaluate the transfer and expression of the double genes in cord blood CD34+ cells. The cDNA encoding MGMT was verified by DNA sequencing and the bicistronic retroviral vector was confirmed by restriction endonuclease analysis. The purity of cord blood CD34+ cells was approximately 92% and recover rate was 75%, the highest titer of recombinant amphotropic retrovirus in the supernatant was up to 5.8 x 10(5) cfu/ml. The efficiency of gene transduction was 18% and 20% tested by colony formation and PCR, respectively. No helper virus was found by both nested PCR and rescue assay. The results showed that dual drug resistance genes have been integrated into the genomic DNA of cord blood CD34+ cells and expressed efficiently. The MTT analysis showed a 4.5 to 7.8-fold increase of resistance of transducted cells to BCNU and P-glycoprotein effluxed drug as compared with the nontransduced cells. This study provided a foundation for ameliorating combination chemotherapy toxicity in tumor clinical trial.

GABA transporter 1 transcriptional starting site exhibiting tissue specific difference

GABA transporter 1(GAT1) takes important roles in multiple physiological processes through the uptake and release of GABA, but the regulation of GAT1 gene expression in different tissues is rarely known. To address the question, first, 5' Rapid amplification of cDNA end (RACE) was used to determine GAT1 transcriptional starting sites in neonatal mouse cerebral cortex and intestine, adult mouse brain and adult rat testis. The products of 5'RACE were confirmed by DNA sequencing. We found that the transcript of GAT1 in neonatal mouse cerebral cortex and adult mouse brain starts at the same site (inside of exon 1), while in mouse intestine, GAT1 starts transcription in intron 1, and in rat testis, the transcript of GAT1 has an additional untranslation exon to the 5' direction.

Adenovirus-mediated expression of pig alpha(1, 3) galactosyltransferase reconstructs Gal alpha(1, 3) gal epitope on the surface of human tumor cells

Gal alpha(1, 3) Gal (gal epitope) is a carbohydrate epitope and synthesized in large amount by alpha(1, 3) galactosyltransferase [alpha(1, 3) GT] enzyme on the cells of lower mammalian animals such as pigs and mice. Human has no gal epitope due to the inactivation of alpha(1, 3) GT gene but produces a large amount of antibodies (anti-Gal) which recognize Gal alpha(1, 3) Gal structures specifically. In this study, a replication-deficient recombinant adenoviral vector Ad5sGT containing pig alpha(1, 3) GT cDNA was constructed and characterized. Adenoviral vector-mediated transfer of pig alpha(1, 3) GT gene into human tumor cells such as malignant melanoma A375, stomach cancer SGC-7901, and lung cancer SPC-A-1 was reported for the first time. Results showed that Gal epitope did not increase the sensitivity of human tumor cells to human complement-mediated lysis, although human complement activation and the binding of human IgG and IgM natural antibodies to human tumor cells were enhanced significantly after Ad5sGT transduction. Appearance of gal epitope on the human tumor cells changed the expression of cell surface carbohydrates reacting with Ulex europaeus I (UEA I) lectins, Vicia villosa agglutinin (VVA), Arachis hypogaea agglutinin (PNA), and Glycine max agglutinin (SBA) to different degrees. In addition, no effect of gal epitope on the growth in vitro of human tumor cells was observed in MTT assay.

Overexpression of gamma-aminobutyric acid transporter subtype I leads to cognitive deterioration in transgenic mice

AIM

To explore the physiological role of gamma-aminobutyric acid transporter subtype I (GAT1) in cognition.

METHODS

Transgenic mice were produced by pronuclei microinjection method. Integration of transgene was identified by Southern-blot and PCR analysis in various generations. Level of GAT1 mRNA in a variety of tissues was evaluated by semi-quantitative RT-PCR analysis. GAT1 protein was detected by immunofluorescence and histochemistry analysis. Associative learning capacity was analyzed by conditioned avoidance task. Memory retention was assessed by novel object recognition test. Morphology of synaptosomes was examined by electron microscope.

RESULTS

Four independent founder mice bearing various copies of transgene were generated. GAT1 was evidently overexpressed at both mRNA and protein level in a variety of tissues from transgenic mice. In comparison with wild-type mice, transgenic mice exhibited significantly declined associative learning capacity (P < 0.01) and decreased memory retention (P < 0.01 in 1-h-retention, and P < 0.05 in 1-d-retention). In addition, the amount of asymmetric synapses in the brain of transgenic mice was reduced approximately by 24 %, relative to wild-type mice.

CONCLUSION

Overexpression of GAT1 in mice results in cognitive deterioration, indicating that the alteration in the expression of gamma-aminobutyric acid transporters is involved in the pathophysiological mechanism underlying some cognitive deficiencies.

Transgenic mice ubiquitously expressing human Fas ligand develop a slight form of graft-versus-host-like disease

AIM

To construct transgenic mice bearing human Fas ligand (FasL/CD95L) cDNA, and further explore the physiological effects of ubiquitous expression of FasL on such animals.

METHODS

Transgenic mice were produced by pronuclei microinjection method. Integration and transmission of transgene were identified by nest-PCR and Southern-blot analysis. Level of FasL mRNA was evaluated by semi-quantitative RT-PCR analysis. FasL protein was detected by immunofluorescence analysis. Morphological alterations in tissues were analyzed by histological examination. The percentage of alphabetaT cells in the spleen was determined by flow cytometry analysis.

RESULTS

Two independent founder mice bearing human FasL cDNA under the control of CMV promoter were generated healthily. Human FasL was moderately expressed in the majority of tissues examined in F1 heterozygotic mice. Although developing normally, adult transgenic mice exhibited a slight form of graft-versus-host (GVH)-like disease characterized by many morphological abnormalities occurring locally in the spleen, testis, lung and liver. In addition, the percentage of alphabetaT cells in the spleen was respectively decreased approximately by 32 % and 24 % in two independent transgenic lines, relative to wild-type mice.

CONCLUSION

Ubiquitous expression of Fas ligand can lead to slight GVH-like disease

Orphanin FQ: an endogenous antagonist of rat brain dopamine transporter

Orphanin FQ, also known as nociceptin (NC),is a well-known ligand for opioid receptor-like ORLI receptor. This heptadecapeptide was identified as potently inhibiting the uptake of rat dopamine transporter (rDAT) which is stably expressed in CHO cells (designated D8 cells). Further kinetic analysis proved that this occurs through competitive inhibition with an IC50 of about 1.9 microM. Orphanin FQ also inhibits [3H]dopamine uptake by rat striatal synaptosomes, which confirmed the effect of orphanin FQ on D8 cells. Orphanin FQ was also found to inhibit GABA transporter type I (GATI) but not the serotonin transporter. These results suggest that orphanin FQ is an endogenous antagonist of dopamine transport and that it affects locomotion and other activities at least partly by inhibiting dopamine transporter and directly affecting dopamine transmission or by inhibiting GABA transporter to indirectly change dopaimne transmission.

Human xenoreactivity is reduced in mice bearing porcine antisense alpha(1,3) galactosyltransferase cDNA

AIM

To explore the effect of antisense alpha(1,3) galactosyltransferase alpha(1,3) GT cDNA on production of Gal alpha(1,3) Gal (Gal epitope) xenoantigen in vivo.

METHODS

Transgenic mice bearing the porcine antisense alpha(1,3) GT cDNA (nt 1alpha-640) were generated by pronuclei microinjection method. The integration of transgene was identified by PCR and Southern-blot analysis. The expression of murine alpha(1,3) GT was characterized by RT-PCR. Morphology of the spleen was examined by histological technique. Gal epitope was detected by immunofluorescent analysis. Binding of human natural xenoantibodies (IgM and IgG) and complement (C3c) to cells from mice was determined by flow cytometric assay.

RESULTS

Transgenic mice bearing the porcine antisense alpha(1,3) GT cDNA were born healthy and developed normally. However, necrosis occurred in the spleen of some mice heterozygous for transgene. Cell surface Gal epitope in transgenic heterozygotes was evidently reduced. Substantially less (30 % - 60 %) xenoantibodies in human serum bound to cells from a variety of tissues of transgenic heterozygotes compared with wild-type controls. Consequentially, human complement activation on cells from these mice was reduced by 40 % - 50 %.

CONCLUSION

Human xenoreactivity could be effectively reduced by inhibiting the expression of alpha(1,3) galactosyltransferase with an antisense gene.

Overexpression of gamma-aminobutyric acid transporter subtype I leads to susceptibility to kainic acid-induced seizure in transgenic mice

Gamma-aminobutyric acid (GABA) is the principal inhibitory neurotransmitter, and the GABAergic synaptic transmission is normally terminated by the rapid uptake through GABA transporters. With transgenic mice ubiquitously overexpressing GABA transporter subtype I (GAT1), the present study explored the pathophysiological role of GAT1 in epileptogenesis. Though displaying no spontaneous seizure activity, these mice exhibit altered electroencephalographic patterns and increased susceptibility to seizure induced by kainic acid. In addition, the GABA(A) receptor and glutamate transporters are up-regulated in transgenic mice, which perhaps reflects a compensatory or corrective change to the elevated level of GAT1. These preliminary findings support the hypothesis that excitatory and inhibitory neurotransmission, and seizure susceptibility can be altered by neurotransmitter transporters.

Transgenic mice overexpressing gamma-aminobutyric acid transporter subtype I develop obesity

Transgenic mice ubiquitously overexpressing murine gamma-aminobutyric acid transporter subtype I were created. Unexpectedly, these mice markedly exhibited heritable obesity, which features significantly increased body weight and fat deposition. Behavioral examination revealed that transgenic mice have slightly reduced spontaneous locomotive capacity and altered feeding pattern. This preliminary finding indicates that the inappropriate level of gamma-aminobutyric acid transporters may be directly or indirectly involved in the pathogenic mechanism underlying certain types of obesity.

Adenovirus-mediated expression of antisense RNA transcripts complementary to pig alpha(1,3) galactosyltransferase mRNA inhibits expression of Gal alpha(1,3) Gal epitope

AIM

To examine the effects of the expression of antisense RNA transcripts complementary to the pig alpha(1,3) galactosyltransferase [alpha(1,3)GT]mRNA on the expression of Gal alpha(1,3) Gal structure (gal epitope) in cultured cell lines.

METHODS

Human adenoviral vectors were used to mediate the expression of antisense RNA. The expression levels of H blood group antigens and gal epitopes were analyzed by flow cytometry using FITC-UEA-I and FITC-GS-IB4 lectins, respectively.

RESULTS

Recombinant adenoviruses, Ad5anti-sGT600 and Ad5-anti-sGT1100, which express antisense RNA complementary to different regions of the pig alpha(1,3) GT mRNA, were constructed and used to infect cell line of NIH3T3. The results showed about 30% reduction in the expression level of gal epitopes on the surface of NIH3T3 cells. In addition, co-expression of human secretor type alpha(1,2) fucosyltransferase [alpha(1,2)FT]cDNA and antisense RNA complementary to the pig alpha(1,3) GT mRNA led to a further reduction in the gal epitope level.

CONCLUSION

Recombinant adenoviruses, Ad5anti-sGT600 and Ad5anti-sGT1100, are effective to down-regulate the gal epitope expression.

Adenovirus-mediated expression of human secretor type alpha(1,2) fucosyltransferase reduces level of Gal alpha(1,3)Gal epitope

AIM

To test the potential of human secretor type alpha(1, 2) fucosyltransferase [Se alpha(1,2)FT] to downregulate the expression of Gal alpha(1,3)Gal epitope (gal epitope) in cultured cell lines.

METHODS

Expression of Se alpha(1,2) FT was mediated by human adenoviral vector. Flow cytometric analysis was used to compare the expression level of H blood group antigen or gal epitope. MTT was employed to assess the susceptibility of mouse NIH3T3 cells to human natural antibody and complement mediated lysis.

RESULTS

A recombinant replication-deficient adenovirus (rAdv) containing human Se alpha(1,2)FT cDNA (Ad5hSeFT) was designed and successfully constructed. Flow cytometric analysis showed that after mock infection, Ad5null infection, and Ad5hSeFT infection, the mean fluorescence intensity (MFI) values for the binding of Ulex europaeus I (UEA-I) lectin to NIH3T3 cells were 2.3 +/- 0.6, 2.1 +/- 1.0, and 36.5 +/- 5.9, respectively; MFI values for the binding of Griffonia simplicifolia isolectin B4 (GS-IB4) lectin to NIH3T3 cells were 167 +/- 23, 170 +/- 19, and 100 +/- 14, respectively; MFI values for the binding of human natural IgG and IgM antibodies to NIH3T3 cells were 31 +/- 3, 32 +/- 4, and 22 +/- 4, respectively.

CONCLUSION

H blood group antigen was detected on NIH3T3 cells after Ad5hSeFT infection and resulted in more than 40% reduction in the level of gal epitope on the cell surface. This reduction increased the resistance of NIH3T3 cells to lysis by normal human serum.

Functional significance of N- and C-terminus of the amino acid transporters EAAC1 and ASCT1: characterization of chimeric transporters

To localize functionally significant domains in the amino acid transporters of mouse brain mEAAC1 and mASCT1, cRNA encoding for wild-type and chimeric transporters was injected into Xenopus oocytes. Activity of expressed transporters was investigated by measurements of uptake of 3H-labeled glutamate and serine and of glutamate- and serine-induced currents under voltage clamp. Though all transporters accept glutamate and serine as substrate, the central part of the protein (Ala94-Met418 of mEAAC1 and Ala119-Ile393 of mASCT1) determines substrate selectivity. The C-terminus rectifies the interaction with the respective substrate. A channel mode of the glutamate transporter can be activated by glutamate and serine, and the N- and C-termini of the mEAAC1 seem to be essential for the channel formation.

Endothelin-1 and smooth muscle cells: induction of jun amino-terminal kinase through an oxygen radical-sensitive mechanism

Endothelin-1 (ET-1) has been proposed to contribute to atherogenesis and plaque rupture in coronary heart disease through activation of mitogen-activated protein kinases (MAPKs) in smooth muscle cells (SMCs). Reactive oxygen species (ROS) have been shown to be important signal transduction molecules in SMCs. Thus, the present study aimed to assess the role of ROS in ET-1-mediated activation of c-Jun amino-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) 1/2. Rat SMCs were exposed to ET-1 over time at concentrations from 10(-6) to 10(-10) mol/L, and MAPK activity was quantified. Activation of JNK and ERK was observed with a maximum stimulation at 10(-7) mol/L ET-1. JNK and ERK were activated by ET-1 binding to a single receptor (ET-1A) but differed in their downstream mechanisms: only JNK activation was sensitive to the radical scavenger N-acetylcysteine and diphenylene iodonium, an inhibitor of NADPH oxidase, indicating a role for ROS. The downstream MAPK effector and proinflammatory transcription factor, the activator protein-1 complex, was maximally activated 2 hours after the addition of ET-1. It was mainly composed of the JNK substrate c-Jun, and activation was also dependent on ROS formation. We suggest that plaque activation by ET-1 can be mediated through ROS. It can be hypothesized that the clinical benefit of antioxidants in the treatment of atherogenesis may partially depend on neutralization of ET-1-mediated ROS production.

Differential activation of mitogen-activated protein kinases in smooth muscle cells by angiotensin II: involvement of p22phox and reactive oxygen species

The atherogenic effect of the renin-angiotensin system can be explained, in part, by the influence of its effector, angiotensin II (Ang II), on vascular smooth muscle cell (VSMC) growth. There is evidence that reactive oxygen species (ROS) play a role in the atherogenesis and activation of mitogen-activating protein (MAP) kinases, which are involved in proliferation and differentiation. The study was performed to further characterize the role of ROS in Ang II-mediated MAP kinase activation and the regulation of the transcription factor activator protein-1 (AP-1). Rat VSMCs were stimulated with Ang II. The activities of MAP kinases were assessed by Western blot analysis or by immunocomplex kinase assay. AP-1 binding was determined by using an electrophoretic mobility shift assay. Rat VSMCs were treated with Ang II-activated MAP kinases, extracellular signal-regulated kinase (ERK), c-Jun amino terminal kinase (JNK), p38 MAP kinase (p38 MAPK), and their downstream effector, AP-1. Interestingly, only the activation of ERK1/2, but not JNK or p38 MAPK, was tyrosine kinase, protein kinase C, and MEK1/2 dependent. Ang II also induced the rapid formation of ROS, which could be inhibited by a specific antibody as well as by antisense against the p22phox subunit of the NAD(P)H oxidase. JNK and p38 MAPK, but not ERK, activation was inhibited by an inhibitor of NAD(P)H oxidase. Antisense against p22phox also solely inhibited p38 MAPK but did not affect ERK. The results indicate that in VSMCs, Ang II activates MAP kinases and AP-1 through different pathways; the results further suggest that ROS, generated by p22phox, mediate Ang II-induced JNK and p38 MAPK activation, which may contribute to the pathogenesis of atherosclerosis.

[Cloning and analyzing of members of excitatory amino acid transporter family from neonatal mouse brain]

Excitatory amino acid transporter family (EAAT) contains several structure-related membrane proteins. They are essential for the removal of glutamate released from pre-synaptic terminal to terminate its action of synaptic transduction and maintaining the normal concentration of neurotransmitters in nerve system. To study these proteins in single animal model, we cloned several members of EAAT family, named mGLAST-1, mGLT-1, mEAAC1 and mASCT1, from a neonatal mouse brain cDNA library. The cDNA sequence of mASCT1 was firstly reported in mouse, it is composed of 3787 bp which has an open reading frame (ORF) encoding a protein of 532 amino acid residues. The mASCT1 protein was expressed in Xenopus oocyte and the function was characterized by 3H-Ser uptaking. The homology between human ASCT1 and mouse ASCT1 is 89.3%. The DNA sequence data shows the variance in length and composition exists in the sequence of 5'UTR and 3'UTR of mRNA in the family members of EAAT. This phenomenon may indicate a post-transcription regulation mechanism might exist in the gene expression of mouse EAAT family members.

Gamma-aminobutyric acid transporter (GAT1) overexpression in mouse affects the testicular morphology

Gamma-aminobutyric acid and GABAergic receptors were previously reported to be distributed in reproductive systems besides CNS and predicted to participate in the modulation of testicular function. Gamma-aminobutyric acid transporter was implicated to be involved in this process. However, the potential role of gamma-aminobutyric transporter in testis has not been explored. In this study, we investigated the existence of mouse gamma-aminobutyric acid transporter subtype I (mGAT1) in testis. Wild-type and transgenic mice, which overexpressing mGAT1 in a variety of tissues, especially in testis, were primarily studied to approach the profile of mGAT1 in testis. Mice with overexpressed mGAT1 develop normally but with reduced mass and size of testis as compared with wild-type. Testicular morphology of transgenic mice exhibited overt abnormalities including focal damage of the spermatogenic epithelium accompanied by capillaries proliferation and increased diameter of seminiferous tubules lumen. Reduced number of spermatids was also found in some seminiferous tubules. Our results clearly demonstrate the presence of GAT1 in mouse testis and imply that GAT1 is possibly involved in testicular function.

[Study on the interaction between the 5' proximal region of mGAT-1 and nuclear proteins by the method of SPR]

The DNA fragment (named F182) corresponding the position of -1775(-)-1594 in the mouse GABA transporter 1 (mGAT-1) 5' proximal region was amplified by PCR. Then the DNA was immobilized to the surface of sensor chip SA5 via biotin-streptavidin linkage. The interaction between the F182 on SA5 and nuclear proteins from mouse liver and kidney was studied by the method of SPR with Biosensor of BIAcore-1000 respectively. The Binding between F182 and two nuclear proteins was definitely and specifically and both with the apparent dissociation rate of about 1.4E-5/s. Competitive experiment revealed that a conserved sequence within F182 had the main contribution to the binding event.

Nuclear proteins from liver and kidney bind a 37 bp sequence in the 5' upstream region of the mGAT1 gene

The mouse GABA transporter (mGAT1) gene has been shown to be exclusively expressed in brain by Northern and Western blot analyses. The interactions between the 5' flanking region of the mGAT1 gene and nuclear proteins from different mouse tissues were studied by means of gel-shift assay. Our results show that nuclear protein factors from non-nervous tissues can specifically recognize a 37 bp sequence that is conserved in the 5' flanking region between the human and mouse GAT1 genes. Similar nuclear protein factors were also found to exist in rat, rabbit and pig.

Effect of mutation of glycosylation sites on the Na+ dependence of steady-state and transient currents generated by the neuronal GABA transporter

The GABA (gamma-aminobutyric acid) transporter (GAT1) belongs to a superfamily of secondary active uptake systems for neurotransmitters that depend on the electrochemical gradients for Na+ and Cl-. In the GAT1, two Na+ ions and one Cl- ion are co-transported with one GABA molecule. Steady-state transport activity and transient charge movements during partial reactions of the transport cycle of the GAT1 of mouse brain expressed in Xenopus oocytes were investigated by two-electrode voltage clamp. Functional expression was demonstrated by Na+-dependent [3H]GABA uptake. Effects of mutation of two out of three N-glycosylation sites located in the extracellular loop between transmembrane domains 3 and 4 (Asn176, Asn181, Asn184) were analysed. Simultaneous substitution of two Asn by Asp leaves the transport system intact but leads to a reduction in turnover and complex changes in the interaction of external Na+ with the transport protein. If Asn176 is mutated to Asp and simultaneously Asn181 to Gly, no transport and no charge movements can be detected. In conclusion, mutations of the glycosylation sites result in altered transport, and the local conformation at Asn181 is critical for expression of transport activity.

Val 70, Phe 72 and the last seven amino acid residues of C-terminal are essential to the function of norepinephrine transporter

The norepinephrine transporter(NET) is a member of the Na+/Cl- dependent neurotransmitter transporter family and constitutes the target of several clinically important antidepressants. To delineate the critical amino acid residues and the function of C-terminal in regulating transport activity of NET, here we constructed two site mutants (V70F, F72V; V70I, F72V) and one C-terminal truncated mutant (delta 611-617). The wild type and mutants of NET were expressed in Xenopus oocytes by injection of their cRNA. We found that all of these mutants lost their transport activity. These results indicate that the amino acid residues of V70 and F72, and the last seven amino acids of C-terminal are essential to the transport activity of NET.

Analysis of the 5' flanking sequence of the human norepinephrine transporter gene

The human norepinephrine transporter (NET) gene was cloned and structurally analyzed. The far 5' fragment containing exon 1 (a non-coding exon) and exon 2 was sequenced. The transcription start site of the gene in human brain stem tissue was determined by primer extension analysis. It was found that the gene could be transcribed from multiple starting points. The 5' flanking sequence contains a proximal G-C rich region, one possible GSG element and several SP1 sites. However it does not contain TATA box and CAAT box motifs. Gel shift analysis with nuclear extracts from different tissues of mouse shows that the G-C rich region may be involved in tissue specific expression of the gene.

Economic transition and health transition: comparing China and Russia

Drawing on experiences from China and Russia (the world's two largest transitional economies), this paper empirically examines the impact of economic reforms on health status. While China's overall health status continued to improve after the economic reform, Russia experienced a serious deterioration in its population health. The observed differences in health performance between China and Russia can be explained by the different impacts of economic reforms on three major socioeconomic determinants of health. Depending on whether or not the reform improves physical environment (as reflected in income level and nutritional status), social environment (including social stability and security system), and health care, we would observe either a positive or a negative net effect on health. Despite remarkable differences in overall health development, China and Russia share some common problems. Mental and social health problems such as suicides and alcohol poisoning have been on the rise in both countries. These problems were much more serious in Russia, where political and social instability was more pronounced, associated with Russia's relatively radical reform process. With their economies moving toward a free market system, health sectors in China and Russia are undergoing marketization, which has had serious detrimental effect on the public health services.

Characterization of 5'-proximal sequence of mouse GABA transporter gene (GAT-1)

The cDNA molecule encoding the mouse GABA transporter gene (GAT-1) was used as probe for selecting GAT-1 gene from mouse genomic library. A positive clone, harboring the whole open reading frame of the GAT-1 protein and designated as MGABAT-G, was fished out from the library, the 5' proximal region and intron 1 were sequenced and analysed, and low homology was found in the above region between GAT-1 genes from mouse and human except some short conserved sequences. The DNA-protein interactions between DNA fragments containing the conserved sequences in the 5' proximal region and nuclear proteins from different tissues of mouse were studied by means of gel-shift assay, and Southern-Western blot. The results indicate a possible positive-negative regulation mode controlling the expression of the mouse GAT-1 gene.

Molecular cloning and structure of the human (GABATHG) GABA transporter gene

A cDNA molecule encoding the human GABA transporter was synthesized by means of polymerase chain reaction (PCR) technique and used as probe for selecting a human genomic DNA fragment encoding GABA transporter. A positive clone harboring the whole gene was obtained from a human lymphocyte genomic library through utilizing the genomic 'walking' technique. The clone, designated as pHGAT, harbours a DNA fragment of about 39 kb in length inserted into the BamHI site in cosmid pWE15. The gene covers about 25 kb in length and is constituted by four EcoRI restricted fragments which are 13.7 kb, 3.1 kb, 4.2 kb and 7.2 kb long, respectively. The genomic clone contains 15 introns, including two introns prior to the initiator methionine (i.e., the translation start site is in exon 3). Eleven exons encode the twelve transmembrane regions in the transporter protein. Thus as in the case for a number of other membrane proteins, there appears to be a strong tendency for the putative transmembrane domains to be encoded by separate exons. It is noted that the structure of the human GABA transporter gene reported here differs from the mouse gene which is contains 12 introns.