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1.
Regulation of γ-Aminobutyric Acid Synthesis in the Brain 总被引:3,自引:3,他引:0
Abstract: γ-Aminobutyric acid (GABA) is synthesized in brain in at least two compartments, commonly called the transmitter and metabolic compartments, and because reglatory processes must serve the physiologic function of each compartment, the regulation of GABA synthesis presents a complex problem. Brain contains at least two molecular forms of glutamate decarboxylase (GAD), the principal synthetic enzyme for GABA. Two forms, termed GAD65 and GAD67, are the products of two genes and differ in sequence, molecular weight, interaction with the cofactor, pyridoxal 5′-phosphate (pyridoxal-P), and level of expression among brain regions. GAD65 appears to be localized in nerve terminals to a greater degree than GAD67, which appears to be more uniformly distributed throughout the cell. The interaction of GAD with pyridoxal-P is a major factor in the short-term regulation of GAD activity. At least 50% of GAD is present in brain as apoenzyme (GAD without bound cofactor; apoGAD), which serves as a reservoir of inactive GAD that can be drawn on when additional GABA synthesis is needed. A substantial majority of apoGAD in brain is accounted for by GAD65, but GAD67 also contributes to the pool of apoGAD. The apparent localization of GAD65 in nerve terminals and the large reserve of apo-GAD65 suggest that GAD65 is specialized to respond to short-term changes in demand for transmitter GABA. The levels of apoGAD and the holoenzyme of GAD (holoGAD) are controlled by a cycle of reactions that is regulated by physiologically relevant concentrations of ATP and other polyanions and by inorganic phosphate, and it appears possible that GAD activity is linked to neuronal activity through energy metabolism. GAD is not saturated by glutamate in synaptosomes or cortical slices, but there is no evidence that GABA synthesis in vivo is regulated physiologically by the availability of glutamate. GABA competitively inhibits GAD and converts holo- to apoGAD, but it is not clear if intracellular GABA levels are high enough to regulate GAD. There is no evidence of short-term regulation by second messengers. The syntheses of GAD65 and GAD67 proteins are regulated separately. GAD67 regulation is complex; it not only is present as apoGAD67, but the expression of GAD67 protein is regulated by two mechanisms: (a) by control of mRNA levels and (b) at the level of translation or protein stability. The latter mechanism appears to be mediated by intracellular GABA levels. 相似文献
2.
Karen F. Greif Mark G. Erlander Niranjala J. K. Tillakaratne Allan J. Tobin 《Neurochemical research》1991,16(3):235-242
The recent identification of two genes encoding distinct forms of the GABA synthetic enzyme, glutamate decarboxylase (GAD), raises the possibility that varying expression of the two genes may contribute to the regulation of GABA production in individual neurons. We investigated the postnatal development the two forms of GAD in the rat cerebellum. The mRNA for GAD67, the form which is less dependent on the presence of the cofactor, pyridoxal phosphate (PLP), is present at birth in presumptive Purkinje cells and increases during postnatal development. GAD67 mRNA predominates in the cerebellum. The mRNA for GAD65, which displays marked PLP-dependence for enzyme activity, cannot be detected in cerebellar cortex by in situ hybridization until P7 in Purkinje cells, and later in other GABA neurons. In deep cerebellar nuclei, which mature prenatally, both forms of GAD mRNA can be detected at birth. The amounts of immunoreactice GAD and GAD enzyme activity parallel changes in mRNA levels. We suggest that the delayed appearance of GAD65 is coincident with synapse formation between GABA neurons and their targets during the second postnatal week. GAD67 mRNA may be present prior to synaptogenesis to produce GABA for trophic and metabolic functions.Special issue dedicated to Dr. Eugene Roberts. 相似文献
3.
Seeds germination is strictly controlled by environment factor such as
high temperature (HT) through altering the balance between gibberellin acid (GA)
and abscisic acid (ABA). Gama-aminobutyric acid (GABA) is a small molecule
with four-carbon amino acid, which plays a crucial role during plant physiological
process associated with pollination, wounding or abiotic stress, but its role in
seeds germination under HT remains elusive. In this study we found that HT
induced the overaccumulation of ROS, mainly H2O2 and O2-
, to suppress seeds
germination, meanwhile, HT also activated the enzyme activity of GAD for the
rapid accumulation of GABA, hinting the regulatory function of GABA in controlling seeds germination against HT stress. Applying GABA directly attenuated
HT-induced ROS accumulation, upregulated GA biosynthesis and downregulated
ABA biosynthesis, ultimately enhanced seeds germination. Consistently, genetic
analysis using the gad1/2 mutant defective in GABA biosynthesis, or pop2-5
mutant with high endogenous GABA content supported the potential function
of GABA in improving seeds germination tolerance to HT through scavenging
ROS overaccumulation. Based on these data, we propose that GABA acts as a
novel signal to enhance thermotolerance of seeds germination through alleviating
the ROS damage to seeds viability. 相似文献
4.
5.
Recent studies of the hippocampus have suggested that a network of genes is associated with the regulation of the GAD67 (GAD1) expression and may play a role in γ-amino butyric acid (GABA) dysfunction in schizophrenia (SZ) and bipolar disorder (BD). To obtain a more detailed understanding of how GAD67 regulation may result in GABAergic dysfunction, we have developed an in vitro model in which GABA cells are differentiated from the hippocampal precursor cell line, HiB5. Growth factors, such as PDGF, and BDNF, regulate the GABA phenotype by inducing the expression of GAD67 and stimulating the growth of cellular processes, many with growth cones that form appositions with the cell bodies and processes of other GAD67-positive cells. These changes are associated with increased expression of acetylated tubulin, microtubule-associated protein 2 (MAP2) and the post-synaptic density protein 95 (PSD95). The addition of BDNF, together with PDGF, increases the levels of mRNA and protein for GAD67, as well as the high affinity GABA uptake protein, GAT1. These changes are associated with increased concentrations of GABA in the cytoplasm of “differentiated” HiB5 neurons. In the presence of Ca2+ and K+, newly synthesized GABA is released extracellularly. When the HiB5 cells appear to be fully differentiated, they also express GAD65, parvalbumin and calbindin, and GluR subtypes as well as HDAC1, DAXX, PAX5, Runx2, associated with GAD67 regulation. Overall, these results suggest that the HiB5 cells can differentiate into functionally mature GABA neurons in the presence of gene products that are associated with GAD67 regulation in the adult hippocampus. 相似文献
6.
Yahr P 《Hormones and behavior》2011,59(4):473-476
The medial preoptic nucleus (MPN) and ventral bed nuclei of the stria terminalis (BST) are needed to maintain mating in sexually experienced male gerbils and rats. The gerbil ventral BST is also activated with mating, as assessed by Fos expression, as is the medial MPN (MPNm) of both species. In gerbils, many of those mating-activated cells contain glutamic acid decarboxylase (GAD), the enzyme that synthesizes γ-aminobutyric acid (GABA). Some of those cells are projection neurons, but others may release GABA locally. Through actions in the medial preoptic area, GABA inhibits and testosterone (T) promotes male sex behavior. Thus, T may promote mating, in part, by decreasing GAD in MPNm or ventral BST cells. In rats, T increases GAD mRNA in the central MPN (MPNc), where MPN GABAergic cells are densest, but mating behavior does not change in sexually experienced males when the MPNc is ablated. Therefore, this study focused on the MPNm and ventral BST to ask whether their GABAergic cells respond to T or are sexually dimorphic. This was done by visualizing cells immunoreactive (IR) for GAD67, an isoform found primarily in cell bodies, in male and female gerbils and in castrated males with and without T. At both sites, males had more GAD67-IR cells than females, and T decreased GAD67-IR cell numbers in males. Thus, the MPNm and ventral BST have GABAergic cells that are sexually dimorphic and in which T decreases GAD, consistent with local effects of T and GABA on mating. 相似文献
7.
Glutamate decarboxylase (GAD) produces GABA, the main inhibitory neurotransmitter in adult mammalian brain. The physical characteristics
of GAD were studied using mass spectrometry and partial protein digests. The N-termini of the two main isoforms, GAD65 and GAD67, were processed by removal of the initial methionine residues and acetylation of the penultimate alanines. Native recombinant
GAD65 and GAD67 exist as homodimers that can be dissociated with non-reducing methods, indicating that homodimerization does not involve
intermolecular disulfide bonds. Truncation of the N-terminal segment with trypsin digestion did not affect homodimerization
but increased activity by decreasing the Km of GAD67 and increasing the Vmax of both isoforms. Of the 15 cysteines in GAD65, the six found in the N-terminal segment can form disulfide bonds and of the 13 cysteines in GAD67, cysteines 32 and 38 can form a disulfide bond. The in vitro formation of disulfide bonds in the N-termini, and the removal of the termini with relatively low amounts of trypsin, indicate
that the N-terminal segments of GAD65 and GAD67 are exposed and flexible. The formation of a disulfide bridge between cysteines 30 and 45 of GAD65 suggests that alteration of normal redox conditions could affect GAD targeting. 相似文献
8.
Thomas Ilg Michael Berger Sandra Noack Andreas Rohwer Michael Gaßel 《Insect biochemistry and molecular biology》2013,43(2):162-177
Glutamate decarboxylase (l-glutamate 1-carboxylyase, E.C. 4.1.1.15, GAD) is the rate-limiting enzyme for the production of γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in vertebrates and invertebrates. We report the identification, isolation and characterization of cDNAs encoding GAD from the parasitic arthropods Ctenocephalides felis (cat flea) and Rhipicephalus microplus (cattle tick). Expression of the parasite GAD genes and the corresponding Drosophila melanogaster (fruit fly) GAD1 as well as the mouse GAD65 and GAD67 genes in Escherichia coli as maltose binding protein fusions resulted in functional enzymes in quantities compatible with the needs of high throughput inhibitor screening (HTS). A novel continuous coupled spectrophotometric assay for GAD activity based on the detection cascade GABA transaminase/succinic semialdehyde dehydrogenase was developed, adapted to HTS, and a corresponding screen was performed with cat flea, cattle tick and fruit fly GAD. Counter-screening of the selected 38 hit substances on mouse GAD65 and GAD67 resulted in the identification of non-specific compounds as well as inhibitors with preferences for arthropod GAD, insect GAD, tick GAD and the two mouse GAD forms. Half of the identified hits most likely belong to known classes of GAD inhibitors, but several substances have not been described previously as GAD inhibitors and may represent lead optimization entry points for the design of arthropod-specific parasiticidal compounds. 相似文献
9.
Conor Feehily Aiden Finnerty Pat G. Casey Colin Hill Cormac G. M. Gahan Conor P. O’Byrne Kimon-Andreas G. Karatzas 《PloS one》2014,9(11)
The glutamate decarboxylase (GAD) system has been shown to be important for the survival of Listeria monocytogenes in low pH environments. The bacterium can use this faculty to maintain pH homeostasis under acidic conditions. The accepted model for the GAD system proposes that the antiport of glutamate into the bacterial cell in exchange for γ-aminobutyric acid (GABA) is coupled to an intracellular decarboxylation reaction of glutamate into GABA that consumes protons and therefore facilitates pH homeostasis. Most strains of L. monocytogenes possess three decarboxylase genes (gadD1, D2 & D3) and two antiporter genes (gadT1 & gadT2). Here, we confirm that the gadD3 encodes a glutamate decarboxylase dedicated to the intracellular GAD system (GADi), which produces GABA from cytoplasmic glutamate in the absence of antiport activity. We also compare the functionality of the GAD system between two commonly studied reference strains, EGD-e and 10403S with differences in terms of acid resistance. Through functional genomics we show that EGD-e is unable to export GABA and relies exclusively in the GADi system, which is driven primarily by GadD3 in this strain. In contrast 10403S relies upon GadD2 to maintain both an intracellular and extracellular GAD system (GADi/GADe). Through experiments with a murinised variant of EGD-e (EGDm) in mice, we found that the GAD system plays a significant role in the overall virulence of this strain. Double mutants lacking either gadD1D3 or gadD2D3 of the GAD system displayed reduced acid tolerance and were significantly affected in their ability to cause infection following oral inoculation. Since EGDm exploits GADi but not GADe the results indicate that the GADi system makes a contribution to virulence within the mouse. Furthermore, we also provide evidence that there might be a separate line of evolution in the GAD system between two commonly used reference strains. 相似文献
10.
Dr. D. Manor D. L. Rothman G. F. Mason F. Hyder O. A. C. Petroff K. L. Behar 《Neurochemical research》1996,21(9):1031-1041
Brain GABA levels rise and plateau following prolonged administration of the irreversible GABA-transaminase inhibitor vigabatrin
(γ-vinylGABA). Recently it has been shown that increased GABA levels reduces GAD67 protein, one of two major isoforms of glutamic acid decarboxylase (GAD). The effects of GABA elevation on GABA synthesis
were assessed in vivo using1H and13C-edited NMR spectroscopy. Rates of turnover of cortical glutamate and GABA from intravenously administered [1-13C]glucose were measured in α-chloralose anesthetized rats 24 hours after receiving vigabatrin (500 mg/kg, i.p.) and in non-treated
controls. GABA concentration was increased 2-fold at 24 hours (from 1.3±0.4 to 2.7±0.9 μmol/g) and GABA-T activity was inhibited
by 60%. Tricarboxylic acid cycle flux was not affected by vigabatrin treatment compared to non-treated rats (0.47±0.19 versus
0.52±0.18 μmol/g, respectively). GABA-C2 fractional enrichment (FE) measured in acid extracts rose more slowly in vigabatrin-treated
compared to nontreated rats, reaching >90% of the glutamate FE after 3 hours. In contrast, GABA FE≥glutamate FE in non-treated
rats. A metabolic model consisting of a single glutamate pool failed to account for the rapid labeling of GABA from glutamate.
Metabolic modelling analysis based on two (non-communicating) glutamate pools revealed a ∼70% decrease in the rate of GABA
synthesis following vigabatrin-treatment, from 0.14 (non-treated) to 0.04 μmol/g/min (vigabatrin-treated). These findings,
in conjunction with the previously reported differential effects of elevated GABA on the GAD isoforms, suggests that GAD67 may account for a major fraction of cortical GABA synthesis in the α-chloralose anesthetized rat brain in vivo.
Special issue dedicated to Dr. Herman Bachelard. 相似文献
11.
Yasuka Shimajiri Takayuki Oonishi Kae Ozaki Kumiko Kainou Kazuhito Akama 《Plant biotechnology journal》2013,11(5):594-604
Gamma‐aminobutyric acid (GABA) is a non‐protein amino acid commonly present in all organisms. Because cellular levels of GABA in plants are mainly regulated by synthesis (glutamate decarboxylase, GAD) and catabolism (GABA‐transaminase, GABA‐T), we attempted seed‐specific manipulation of the GABA shunt to achieve stable GABA accumulation in rice. A truncated GAD2 sequence, one of five GAD genes, controlled by the glutelin (GluB‐1) or rice embryo globulin promoters (REG) and GABA‐T‐based trigger sequences in RNA interference (RNAi) cassettes controlled by one of these promoters as well, was introduced into rice (cv. Koshihikari) to establish stable transgenic lines under herbicide selection using pyriminobac. T1 and T2 generations of rice lines displayed high GABA concentrations (2–100 mg/100 g grain). In analyses of two selected lines from the T3 generation, there was a strong correlation between GABA level and the expression of truncated GAD2, whereas the inhibitory effect of GABA‐T expression was relatively weak. In these two lines both with two T‐DNA copies, their starch, amylose, and protein levels were slightly lower than non‐transformed cv. Koshihikari. Free amino acid analysis of mature kernels of these lines demonstrated elevated levels of GABA (75–350 mg/100 g polished rice) and also high levels of several amino acids, such as Ala, Ser, and Val. Because these lines of seeds could sustain their GABA content after harvest (up to 6 months), the strategy in this study could lead to the accumulation GABA and for these to be sustained in the edible parts. 相似文献
12.
Improvement of dinitrogen fixation in beans (Phaseolus vulgaris L.) will depend on the selection of superior plant genotypes and the presence of efficient rhizobial strains. This study
was conducted to evaluate diverse bean lines for N2 fixation potential using the15N-depleted dilution technique under field conditions in Wisconsin, USA. Plants of 21 bean lines and three non-nodulating isolines
of soybean received appliin Wisconsin, USA. Plants of 21 bean lines and three non-nodulating isolines of soybean received
applications of15N-depleted ammonium sulphate. Shoots harvested at the V6, R3 and R7 stages and dry seeds were analyzed for total N using the Kjeldahl procedure, and the ratio of15N to14N was determind on a MAT 250 mass spectrometer. Nodule occupancy of the applied strain ofR. leguminosarum biovarphaseoli, CIAT 899, was determined in five of the bean lines. Total shoot N content showed a pattern of accumulation similar to shoot
dry weight and fixed N2 in the shoot. Based on shoot total N, N2 fixed in the shoot and shoot dry weight Riz 30 and Preto Cariri were identified as being as good fixers as Puebla 152 and
Cargamanto appear to begin N2 fixation early. Furthermore, some bean lines that fixed considerable N2 did not translocate a large amount of N to the grains. Preto Cariri accumulated 21.2 kg N ha−1 in the seeds compared to Puebla 152 which accumulated 43.8 kg N ha−1 of the fixed N2 into the grains. At the early sampling, Puebla 152 and 22–27 had a considerable higher percentage of their crown nodules
formed by the inoculant strain CIAT 899, than did Rio Tibagi which has been considered a poor N2 fixer. 相似文献
13.
(1). We investigated the effects of inhibiting d-amino-acid oxidase (DAO) activity on nociceptive responses through the use of mutant ddY/DAO− mice, which lack DAO activity, and through the application of a selective inhibitor of DAO, sodium benzoate, in the tail
flick test, hot-plate test, formalin test, and acetic acid-induced writhing test. (2). Compared with normal ddY/DAO+ mice, ddY/DAO− mice showed significantly prolonged tail withdrawal latency in the tail flick test and licking/jumping latency in the hot-plate
test, as well as significantly reduced duration of licking/biting in the late phase of the formalin test and the number of
abdominal writhing in the acetic acid-induced writhing test. (3). In addition, we investigated the effects of sodium benzoate
in Kunming mice having normal DAO activity. (4). Intravenous administration of sodium benzoate (400 mg/kg) significantly inhibited
pain responses of the late phase of the formalin test and abdominal writhing responses in the acetic acid-induced writhing
test, with no effects on the early phase flinch responses in the formalin test, nociceptive responses in the tail flick test,
or hot-plate test. (5). These results suggest that DAO acts as a pro-nociceptive factor in pain, particularly chronic pain,
transmission and modulation, and may be a target for pain treatment. 相似文献
14.
15.
Wang Qi Xin Yinqiang Zhang Feng Feng Zhiyong Fu Jin Luo Lan Yin Zhimin 《World journal of microbiology & biotechnology》2011,27(3):693-700
γ-aminobutyric acid (GABA) is an important bioactive regulator, and its biosynthesis is primarily through the α-decarboxylation of glutamate by glutamate decarboxylase (GAD). The procedures to obtain GABA by bioconvertion with high activity
recombinant Escherichia coli GAD have been seldom understood. In this study, Escherichia coli GAD (gadA) was highly expressed (about 70–75% of total protein) as soluble protein in Escherichia coli BL21(DE3) containing pET28a-gadA, which was induced by 0.4 mM IPTG in LB medium, and maximal GABA-forming activity of the
recombinant GAD was 40 U/mL at a concentration (0.15 mM) of pyridoxal phosphate (PLP) and a concentration (0.6 mM) of Ca2+ at optimal pH of 3.8. The optimal concentration (7.5 mM) of Mn2+ can also improve the activity of recombinant enzyme, but the co-effect of Ca2+ and Mn2+ exhibited antagonism effect when added simultaneously. LB and 0.1% (w/v) lactose were selected as culture medium and inducer,
respectively. The relative activity was markedly higher activated by Ca2+ (174%), Mn2+ (164%) than that by other seven bivalent cations. Finally, the yield of GABA was high of 94 g/L detected by paper chromatography
or HPLC in 1 L reaction system with 30 mL crude GAD (12 U/mL). By entrapping Escherichia coli glutamate decarboxylase into sodium alginate and carrageenan gel beads, the activity of immobilized GAD (IGAD) remained 85%
during the initial five batches and the activity still remained 50% at the tenth batch, these results indicated that the recombinant
Escherichia coli GAD was feasible for the future industrial production of GABA. 相似文献
16.
Enhancement of shoot regeneration from loblolly pine (Pinus taeda L.) cotyledon explants was studied by addition of abscisic acid (ABA) to Gresshoff-Doy (GD) shoot induction medium containing benzylaminopurine (BA) and naphthaleneacetic acid (NAA). Addition of ABA (10–7 M) doubled the morphogenic area of cotyledons and increased the fresh weight of cotyledon explants by 40 to 45% after 4 weeks. A 4-week exposure to ABA resulted in a larger morphogenic area per cotyledon than 3, 2, or 1 week(s) respectively. The enhancement by ABA was related to the explant seed source and was not increased by prolonged exposure. Compared to controls, shoot number was enhanced by 31% and 56% with 2 and 4 weeks of ABA (10–7 M) exposure, respectively. Abscisic acid has a role in enhancing shoot morphogenesis in loblolly pine.Abbreviations ABA
Abscisic acid
- BA
6-Benzylaminopurine
- GD
Gresshoff and Doy (1972) nutrient medium
- NAA
-Naphthaleneacetic acid. 相似文献
17.
Tina Rambrand Flemming Pociot Kjersti Rønningen Jørn Nerup B. K. Michelsen 《Human genetics》1997,99(2):177-185
Reliable genetic and immunological markers are important in the prediction of insulin-dependent diabetes mellitus (IDDM).
Since glutamic acid decarboxylase (GAD) is a candidate primary autoantigen, we examined the possible linkage between IDDM
and the genes encoding GAD65 (GAD2, 10p11–12) and GAD67 (GAD1, 2q31) in 58 Danish IDDM affected sib pairs. The allelic inheritance of 10 polymorphic dinucleotide repeat sequences spanning
the chromosomal regions of the two GAD genes, were examined by affected sib pair analysis (ASP). In addition a restriction
fragment length polymorphism (RFLP) was identified in the gene encoding GAD65 using the restriction enzyme PvuII. The GAD gene markers were analyzed in relation to the presence of specific HLA types and GAD autoantibodies. No evidence
of linkage was found between IDDM and either of the genes encoding GAD. This was also the case when subgroups carrying specific
HLA susceptibility alleles were analyzed. Nor did we observe any association between these GAD genetic markers and the presence
of GAD autoantibodies. Considering the high prevalence of GAD autoantibodies in IDDM, a putative genetic association between
GAD and IDDM would be expected to affect most diabetic individuals. Therefore, our data indicate that the association between
GAD and IDDM is not genetically determined, and that microsatellites used in this study do not contribute to the prediction
of IDDM.
Received: 1 July 1996 / Revised: 21 August 1996 相似文献
18.
The Effect of Abscisic Acid on the Uptake and Distribution of Ions in Intact Seedlings of Phaseolus vulgaris cv. Redland Pioneer 总被引:3,自引:0,他引:3
Abscisic acid (ABA) was found to increase the accumulation of 36Cl, total Cl, 22Na and total Na+ in roots of intact bean seedlings. After an initial promotion. ABA inhibited longdistance transport of these ions from the root to the shoot. However, it consistently inhibited both uptake and transport of 42K and total K+ in intact bean seedlings. A promotion of net 36Cl influx (ψoc) and its accumulation in the root (Q*v) concomitant decrease in transport index (long-distance transport as percentage of total influx) showed that ABA stimulates -36Cl transport at the tonoplast. It inhibited H4 extrusion and net 86Rb influx which agrees with a cation exchange theory K+/Rb+ transport. 相似文献
19.
Zhaohui Gong Xiange Long Lin Pan Yanping Le Qiong Liu Shaomin Wang Junming Guo Bingxiu Xiao Mi Zhou Disen Mei 《Protein expression and purification》2009,66(2):191-197
Induction of specific immunological unresponsiveness by oral autoantigens such as glutamic acid decarboxylase 65 (GAD65) is termed oral tolerance and may be a potential therapy for autoimmune diabetes. However, the requirement for large amounts of protein will limit clinical testing of autoantigens, which are difficult to produce. Mucosal adjuvants such as cholera toxin B subunit (CTB) may lower the level of autoantigens required. Here we describe cloning, expression, purification and identification study of the CTB and triple GAD531–545 epitopes fusion gene. The fusion gene was ligated via a flexible hinge tetrapeptide and expressed as a soluble protein in Escherichia coli BL21 (DE3) driven by the T7 promoter. We purified the recombination protein from the cell lysate and obtained approximately 2.5 mg of CTB–GAD(531–545)3 per liter of culture with greater than 90% purity by a Ni–NTA resin column. The bacteria produced this protein as the pentameric form, which retained the GM1-ganglioside binding affinity and the native antigenicity of CTB and GAD65. Further studies revealed that oral administration of bacterial CTB–GAD(531–545)3 fusion protein showed the prominent reduction in pancreatic islet inflammation in non-obese diabetic mice. The results presented here demonstrate that the bacteria bioreactor is an ideal production system for an oral protein vaccine designed to develop immunological tolerance against autoimmune diabetes. 相似文献