Increase in drug-induced seizure susceptibility of transgenic mice overexpressing GABA transporter-1

AIM

The changes of seizure susceptibility of transgenic mice overexpressing GABA transporter-1 (GAT-1) were studied to clarify the possible role of GABAergic transmission in epileptogenesis.

METHODS

Seizures were induced by intraperitoneal administration of pentylenetetrazol (PTZ), picrotoxin (PIC), or kainic acid (KA) respectively. The anticonvulsant effect of ethyl nipecotate was tested by its intraperitoneal injection 15 min before the administration of the epileptogenic agents.

RESULTS

The percentages of occurrence of clonic seizures induced by PTZ 45 mg/kg, PIC 2.5 mg/kg, or KA 20 mg/kg in GAT-1 transgenic mice were 88.9 %, 100 %, and 83.3 % respectively, whereas those in control C57BL/6J mice were 42.9 %, 57.1 %, and 33.3 %. The percentages of occurrence of tonic seizures induced by PTZ 45 mg/kg, PIC 2.5 mg/kg, or KA 20 mg/kg in transgenic mice were 88.9 %, 100 %, and 83.3 % respectively, and whereas those in control mice were 28.6 %, 42.9 %, and 16.7 %. The latencies of both clonic and tonic seizures onset in transgenic mice were markedly shortened compared with those in control animals. The results indicated that GAT-1 transgenic mice showed increased susceptibility to seizures induced by the anti-GABAergic convulsive drugs (PTZ, PIC), as well as glutamic receptor agonist (KA). Ethyl nipecotate, inhibitor of GAT-1, inhibited PTZ-induced seizures in both GAT-1 transgenic and C57BL/6J mice. The incidence of seizures was decreased after the application of ethyl nipecotate, and the latencies to the onset of clonic or tonic seizures were also prolonged.

CONCLUSION

The increase in seizure susceptibility of transgenic mice over-expressing GAT-1 is an evidence for involvement of GABAergic transmission in epileptogenesis, and this transgenic mouse might be a useful animal model for study on the role of GABAergic transmission in epileptogenesis.

[Development of salivary gland tumors in pleomorphic adenoma gene 1 transgenic mice]

OBJECTIVE

Activation and overexpression of pleomorphic adenoma (PLAG1) gene due to t(3;8)(p21;q12) translocation are associated with the development of human pleomorphic adenomas of the salivary glands. This study was conducted to generate ubiquitously-expressed or tissue-specific expressed PLAG1 transgenic mice and to elucidate the role of PLAG1 gene in tumorigenesis in vivo.

METHODS

Human PLAG1 cDNA was cloned from salivary gland tumor or placenta tissues by RT-PCR. Ubiquitous expression vector pCMV-EGFP/PLAG1 driven by CMV promoter and tissue-specific expression vector pMMTV-PLAG1 driven by MMTV LTR were constructed. NIH3T3 cells transiently transfected with pCMV-EGFP/PLAG1 showed high expression of PLAG1 in nucleus. Transgenes were microinjected into pronucleus of zygotes to generate transgenic mice.

RESULTS

It was found that the human PLAG1 cDNA cloned from several salivary gland tumor and normal placenta tissues consistently showed a variation of a single nucleotide at the same position when compared with the human PLAG1 cDNA sequence in Genbank (Accession No. U65002), which led to T458P at protein level. It might be a single nucleotide polymorphism (SNP)locus. Fused EGFP/PLAG1 protein was found to be localized in the nucleus of NIH3T3 cells transiently transfected with pCMV-EGFP/ PLAG1. Several pCMV-EGFP/PLAG1 and pMMTV-PLAG1 transgenic mouse lines were obtained respectively. As might be expected, pMMTV-PLAG1 transgenic mice spontaneously developed salivary gland tumors in three independent lines, among which, line 42 showed tumorigenic phenotype in 100% of transgenic mice within three months after birth.

CONCLUSION

Overexpression of PLAG1 gene plays a crucial role in tumorigenesis of salivary gland tumors.

Involvement of dopamine D3 and neuropeptide Y Y5 receptors in diabetic gastroparetic rats without response to erythromycin

Erythromycin may accelerate gastric emptying in animals and human probably as an motilin agonist, but its prokinetic effects show obvious individual disparity. This study was to find the mechanism of this phenomenon. Microarray analysis was used to screen genes that might be involved in the response of diabetic gastroparesis rats to erythromycin. It was found that erythromycin accelerated gastric emptying of diabetic rats with great individual disparity. Through microarray analysis we screened differential expression genes that might be involved in the effect of erythromycin. Among 10 genes screened out, dopamine D3 receptor (DRD3) and neuropeptide Y Y5 receptor (NPYY5) genes were submitted to RT-PCR quantification and showed consistent results with microarray. It can be concluded that erythromycin promote gastric emptying of gastroparetic rats; DRD3 and NPYY5 may be involved in prokinetic action of erythromycin; and targets other than motilin receptor of erythromycin might exist as prokinetics.

Hyperalgesic effects of gamma-aminobutyric acid transporter I in mice

The present study focused on the involvement of gamma-aminobutyric acid transporter I (GAT1) in pain. We found that GABA uptake was increased in mouse spinal cord at 20 min and 120 min after formalin injection and in mouse brain at 120 min, but not 20 min, after formalin injection. In addition, the antinociceptive effects of GAT1-selective inhibitors were examined using assays of thermal (tail-flick) and chemical (formalin and acetic acid) nociception in C57BL/6J mice. The GAT1-selective inhibitors, ethyl nipecotate and NO-711, exhibited significant antinociceptive effects in these nociceptive assays. To study further the effects of GAT1 on pain, we used two kinds of GAT1-overexpressing transgenic mice (under the control of a CMV promoter or a NSE promoter) to examine the nociceptive responses in these mice. In the thermal, formalin, and acetic acid assays, both kinds of transgenic mice displayed significant hyperalgesia after nociceptive stimuli. In addition, the micro opioid receptor antagonist naloxone had no influence on nociceptive responses in wild-type and transgenic mice. The results indicate that GAT1 is involved in the regulation of pain processes, and point to the possibility of developing analgesic drugs that target GAT1 other than opioid receptors.

[Adipose tissue-derived stromal cells differentiate into neuron-like cells]

OBJECTIVE

To investigate the possibility of inducing adipose tissue-derived stromal cells to differentiate into neuron-like cells, and to explore a new cell source for central nervous system transplantation.

METHODS

beta-mercaptoethanol was adopted to induce the cells to differentiate; undifferentiated cells and differentiated cells were identified with immunocytochemistry.

RESULTS

A population of adipose tissue-derived stromal cells were isolated from adult rat adipose tissue; they were processed to obtain a fibroblast-like population of cells and could be maintained in vitro for extended periods with stable population doubling, and they were expanded as undifferentiated cells in culture for more than 10 passages, indicating their proliferative capacity. beta-mercaptoethanol induced the stem cells to express nestin, characteristic of neuronal precursor stem cells at early stage of differentiation, and at late stage they exhibited a neuronal phenotype, expressing neuron-specific enolase (NSE) and neurofilament(NF); with an optimal differentiation protocol, almost 60%-85% of the cells expressed NSE and NF.

CONCLUSION

The data support the hypothesis that adult adipose tissue contains stem cells capable of differentiating into neurons.

A mRNA molecule encoding truncated excitatory amino acid carrier 1 (EAAC1) protein (EAAC2) is transcribed from an independent promoter but not an alternative splicing event

Glutamate transporter EAAC1 removes excitatory neurotransmitter in central nervous system, and also absorbs glutamate in epithelia of intestine, kidney, liver and heart for normal cell growth. When a mouse cDNA was screened using EAAC1 cDNA fragment as probe in our lab, a transcript (GenBank U75214) encoding an EAAC1 protein with 148 residues truncated at N-terminal was cloned and named as EAAC2. Sequence analysis shows that EAAC2 has it's own start code and unique 5'UTR that is different from that of EAAC1. A mouse genomic library was screened and a positive clone including EAAC1 CDS was sequenced (GenBank AF 322393) and indicates that normal EAAC1 transcript (GenBank U73521) is transcribed from 10 exons in terms of exon I, II, III, IV, V, VI, VII, VIII, IX, X, and EAAC2 transcript is consisted by exons from IV to IX as same as that of EAAC1 and with its unique exon beta upstream to exon IV and exon delta downstream to IX. EAAC2 transcript has a cluster of transcriptional start sites not overlapping with the transcriptional start sites of EAAC1. These results indicate that EAAC2 is transcribed from an independent promoter but not an alternative splicing event.

Effects of green tea polyphenols on dopamine uptake and on MPP+ -induced dopamine neuron injury

As antioxidants, polyphenols are considered to be potentially useful in preventing chronic diseases in man, including Parkinson's disease (PD), a disease involving dopamine (DA) neurons. Our studies have demonstrated that polyphenols extracted from green tea (GT) can inhibit the uptake of 3H-dopamine (3H-DA) and 1-methyl-4-phenylpyridinium (MPP(+)) by DA transporters (DAT) and partially protect embryonic rat mesencephalic dopaminergic (DAergic) neurons from MPP(+)-induced injury. The inhibitory effects of GT polyphenols on 3H-DA uptake were determined in DAT-pCDNA3-transfected Chinese Hamster Ovary (DAT-CHO) cells and in striatal synaptosomes of C57BL/6 mice in vitro and in vivo. The inhibitory effects on 3H-MPP(+) uptake were determined in primary cultures of embryonic rat mesencephalic DAergic cells. Inhibition of uptake for both 3H-DA and 3H-MPP(+) was dose-dependent in the presence of polyphenols. Incubation with 50 microM MPP(+) resulted in a significant loss of tyrosine-hydroxylase (TH)-positive cells in the primary embryonic mesencephalic cultures, while pretreatment with polyphenols (10 to 30 microg/ml) or mazindol (10 microM), a classical DAT inhibitor, significantly attenuated MPP(+)-induced loss of TH-positive cells. These results suggest that GT polyphenols have inhibitory effects on DAT, through which they block MPP(+) uptake and protect DAergic neurons against MPP(+)-induced injury.

[Construction of an angiostatin eukaryotic expression vector and characterization of its inhibitory efficiency in B16 melanoma bearing mice]

Recent studies have demonstrated that angiostatin, a newly discovered specific inhibitor of endothelial cells, may significantly suppress the growth of a variety of tumors. We constructed an eukaryotic expression vector containing angiostatin (pAG3 ). To study the effect of pAG3, we intramuscularly injected pAG3 into B16 melanoma bearing C57 mice, we found that pAG3 could obviously inhibit tumor growth and reduce the size of tumors in B16 melanoma bearing C57 mice compared to the untreated control mice. In addition, we also investigated whether pre-treatment of pAG3 can prevent the tumor formation in mice treated with B16 melanoma. Normal C57 mice which received 5 days of treatment of pAG3 prior to implanting tumors resulted in the inhibitory effect when compared to control mice. No promotive effect was observed when pAG3 was combined with DTIC (Dacarbazine). These findings provide a basis for the further development of nonviral delivery of angiogenic gene therapy.

[Long-term culture and differentiation of neural stem cells of embryonic mice]

OBJECTIVES

To assess the culture and differentiation of neural stem cells in embryonic mice and set up a basis for further research in to neural stem cells.

METHODS

Embryonic cortices of mice were dissociated and single cell suspensions were achieved by mechanical methods in sterile conditions, and cells were seeded in uncoated plate in N2 medium. The cells were passaged by mechanical methods, frozen and thawed by general procedure. They were identified by immunocytochemical techniques.

RESULTS

Neural stem cells from embryonic mice were successfully cultured forming typical neurospheres in suspension. Neurons, astrocytes and oligodendrocytes were differentiated from neural stem cells, with a ratio of 7%, 85% - 90% and 2% - 4% respectively.

CONCLUSIONS

Neural stem cells, which can be cultured and passaged steadily in vitro and they are the ideal cell sources for cell transplantation and gene therapy.

Cloning of full length cDNA sequence of the mouse ameloblastin

OBJECTIVE

Screening for special genes of matrix proteins of dentin and enamel of mouse dental germ.

METHODS

A cDNA library of dental germ of mouse was screened by differential display. The interesting clones were sequenced.

RESULTS

Six positive clones were isolated from the cDNA library. The sequence of one of the six positive clones was homologous with the ameloblastin sequence of rat. There are 497 homologous base pairs between the 526 base pairs sequenced by pTriplEX 3' primer of this clone and the 32-580 sequence of the rat ameloblastin gene; and there are 533 homologous base pairs between the 567 base pairs sequenced by pTriplEX 5' primer of this clone and the 1285-1854 sequence of the rat ameloblastin gene.

CONCLUSIONS

The full length cDNA sequence of the mouse ameloblastin was cloned.

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.