γ-aminobutyric acid can be produced by a one-step enzymatic reaction catalyzed by glutamic acid decarboxylase. The reaction system is simple and environmentally friendly. However, the majority of GAD enzymes catalyze the reaction under acidic pH at a relatively narrow range. Thus, inorganic salts are usually needed to maintain the optimal catalytic environment, which adds additional components to the reaction system. In addition, the pH of solution will gradually rise along with the production of γ-aminobutyric acid, which is not conducive for GAD to function continuously. In this study, we cloned the glutamate decarboxylase LpGAD from a Lactobacillus plantarum capable of efficiently producing γ-aminobutyric acid, and rationally engineered the catalytic pH range of LpGAD based on surface charge. A triple point mutant LpGAD^{S24R/D88R/Y309K} was obtained from different combinations of 9 point mutations. The enzyme activity at pH 6.0 was 1.68 times of that of the wild type, suggesting the catalytic pH range of the mutant was widened, and the possible mechanism underpinning this increase was discussed through kinetic simulation. Furthermore, we overexpressed the Lpgad and Lpgad^{S24R/D88R/Y309K} genes in Corynebacterium glutamicum E01 and optimized the transformation conditions. An optimized whole cell transformation process was conducted under 40 ℃, cell mass (OD₆₀₀) 20, 100 g/L l-glutamic acid substrate and 100 μmol/L pyridoxal 5-phosphate. The γ-aminobutyric acid titer of the recombinant strain reached 402.8 g/L in a fed-batch reaction carried out in a 5 L fermenter without adjusting pH, which was 1.63 times higher than that of the control. This study expanded the catalytic pH range of and increased the enzyme activity of LpGAD. The improved production efficiency of γ-aminobutyric acid may facilitate its large-scale production.
Glutamate Decarboxylase/genetics* ; Lactobacillus plantarum/genetics* ; Catalysis ; gamma-Aminobutyric Acid ; Hydrogen-Ion Concentration ; Glutamic Acid

Stress can induce a serious epileptic encephalopathy that occurs during early infancy. Recent studies have revealed that prenatal stress exposure is a risk factor for the development of infantile spasms. Our previous work demonstrates that prenatal stress with betamethasone-induced alterations to the expression of the K⁺/Cl⁻ co-transporter (KCC2) in gamma-aminobutyric acid (GABA) interneurons lowers the seizure threshold in exposed animals. Here, we further investigated the mechanisms involved in this KCC2 dysfunction and explored possible treatment options. We stressed Sprague-Dawley rats prenatally and further treated dams with betamethasone on gestational day 15, which increases seizure susceptibility and NMDA (N-Methyl-D-aspartate)-triggered spasms on postnatal day 15. In this animal model, first, we evaluated baseline calpain activity. Second, we examined the cleavage and dephosphorylation of KCC2. Finally, we checked the effect of a calpain inhibitor on seizure occurrence. The phosphorylated-N-methyl-D-aspartate Receptor 2B (NR2B):non-phosphorylated NR2B ratio was found to be higher in the cortex of the prenatally stressed beta-methasone model. We further found that the betamethasone model exhibited increased phosphorylation of calpain-2 and decreased phosphorylation of KCC2 and Glutamic acid decarboxylase 67 (GAD67). After using a calpain inhibitor in prenatal-stress rats, the seizure frequency decreased, while latency increased. GABAergic depolarization was further normalized in prenatal-stress rats treated with the calpain inhibitor. Our study suggests that calpain-dependent cleavage and dephosphorylation of KCC2 decreased the seizure threshold of rats under prenatal stress. Calpain-2 functions might, thus, be targeted in the future for the development of treatments for epileptic spasms.
Animals ; Betamethasone ; Brain Diseases ; Calpain ; Epilepsy ; gamma-Aminobutyric Acid ; Glutamate Decarboxylase ; Humans ; Infant ; Infant, Newborn ; Interneurons ; Models, Animal ; N-Methylaspartate ; Phosphorylation ; Rats ; Rats, Sprague-Dawley ; Risk Factors ; Seizures ; Spasm ; Spasms, Infantile

Glutamate decarboxylase, a unique pyridoxal 5'-phosphate-dependent enzyme, catalyzes α-decarboxylation of L-glutamate to γ-aminobutyrate. However, glutamate decarboxylase from different sources has the common problem of poor thermostability that affects its application in industry. In this study, proline was introduced at 13 different positions in glutamate decarboxylase by using the design strategy of homologous sequence alignment between Thermococcus kodakarensis and Lactobacillus brevis CGMCC No.1306. A mutant enzyme G364P with higher thermostability was obtained. Compared to the wild type, thermostability of the mutant G364P was significantly improved, the half-life time (t1/2) at 55 °C and the semi-inactivation temperature (T₅₀ ¹⁵) of the mutant G364P increased 19.4 min and 5.3 °C, respectively, while kcat/Km of the mutant enzyme remained nearly unchanged. Further analysis of their thermostability by molecular dynamics simulations were performed. The root mean square deviation of G364P and root mean square fluctuation in the loop region including G364 were lower than the wild type at 313 K for 10 ns, and G364P increased one hydrophobic interaction in the loop region. It proves that mutation of flexible 364-Gly to rigid proline endows glutamate decarboxylase with enhanced thermostability.
Glutamate Decarboxylase ; Glutamic Acid ; Lactobacillus brevis ; Molecular Dynamics Simulation ; Proline

Although extensively studied, the exact role of sleep in learning and memory is still not very clear. Sleep deprivation has been most frequently used to explore the effects of sleep on learning and memory, but the results from such studies are inevitably complicated by concurrent stress and distress. Furthermore, it is not clear whether there is a strict time-window between sleep and memory consolidation. In the present study we were able to induce time-locked slow-wave sleep (SWS) in mice by optogenetically stimulating GABAergic neurons in the parafacial zone (PZ), providing a direct approach to analyze the influences of SWS on learning and memory with precise time-windows. We found that SWS induced by light for 30 min immediately or 15 min after the training phase of the object-in-place task significantly prolonged the memory from 30 min to 6 h. However, induction of SWS 30 min after the training phase did not improve memory, suggesting a critical time-window between the induction of a brief episode of SWS and learning for memory consolidation. Application of a gentle touch to the mice during light stimulation to prevent SWS induction also failed to improve memory, indicating the specific role of SWS, but not the activation of PZ GABAergic neurons itself, in memory consolidation. Similar influences of light-induced SWS on memory consolidation also occurred for Y-maze spatial memory and contextual fear memory, but not for cued fear memory. SWS induction immediately before the test phase had no effect on memory performance, indicating that SWS does not affect memory retrieval. Thus, by induction of a brief-episode SWS we have revealed a critical time window for the consolidation of hippocampus-dependent memory.
Animals ; Cues ; Electroencephalography ; Electromyography ; Evoked Potentials, Motor ; physiology ; Fear ; psychology ; Glutamate Decarboxylase ; metabolism ; Hippocampus ; physiology ; Light ; Luminescent Proteins ; genetics ; metabolism ; Maze Learning ; physiology ; Memory Consolidation ; physiology ; Mice ; Mice, Inbred C57BL ; Mice, Transgenic ; Sleep Deprivation ; Sleep, Slow-Wave ; physiology ; Time Factors ; Vesicular Inhibitory Amino Acid Transport Proteins ; genetics ; metabolism

PURPOSE: Type 1 diabetes mellitus (DM) is associated with autoimmune diseases such as thyroiditis. Therefore, we aimed to investigate the prevalence of autoimmune thyroiditis in patients with type 1 DM. METHODS: A total of 102 patients who were diagnosed and followed up (mean age, 8.1±4.0 years) in Ajou University Hospital were enrolled in this study. All the patients were evaluated for beta cell autoimmunity, including insulin autoantibody, glutamic acid decarboxylase antibodies (GADA), and islet cell antibody. Moreover, autoantibodies to thyroid peroxidase and thyroglobulin were assessed at initial diagnosis and annually thereafter. RESULTS: The mean patient age (49 men and 53 women) was 19.2±4.8 years. The prevalence of at least one thyroid antibody was 30.4%. Patients with thyroid anti­bodies had a significantly higher frequency of GADA at the time of the diagnosis. Autoimmune thyroiditis was more prevalent in the older age group. GADA was a significant risk factor for development of thyroid autoantibodies after diagnosis of type 1 DM (odds ratio, 4.45; 95% confidence interval, 1.399–14.153). CONCLUSIONS: In patients with type 1 DM, the prevalence of autoimmune thyroiditis was higher than in the general population. Moreover, GADA positivity at diagnosis was associated with thyroid autoimmunity.
Antibodies ; Autoantibodies ; Autoimmune Diseases ; Autoimmunity ; Diabetes Mellitus, Type 1 ; Diagnosis ; Follow-Up Studies* ; Glutamate Decarboxylase ; Humans ; Insulin ; Iodide Peroxidase ; Islets of Langerhans ; Male ; Prevalence* ; Risk Factors ; Thyroglobulin ; Thyroid Gland ; Thyroiditis ; Thyroiditis, Autoimmune*

PURPOSE: Infantile spasms, also known as West syndrome, is an age-specific epileptic seizure. Most patients with this condition also exhibit delayed development. This study aimed to determine the effect of long-term prenatal stress on susceptibility to infantile spasms. METHODS: We subjected pregnant rats to acute or chronic immobilization stress. Resulting offspring received N-methyl-D-aspartic acid (15 mg/kg, intraperitoneally) on postnatal day 15, and their behaviors were observed 75 minutes after injection. The expression of KCC2 and GAD67 was also determined using immunohistochemistry. RESULTS: Exposure to long-term prenatal stress increased the frequency of spasms and decreased the latency to onset of spasms compared with offspring exposed to short-term prenatal stress. Expression of KCC2 and GAD67 also decreased in the group exposed to long-term prenatal stress compared with the group exposed to short-term prenatal stress. CONCLUSION: Our study suggests that exposure to long-term prenatal stress results in increased susceptibility to seizures.
Animals ; Epilepsy ; gamma-Aminobutyric Acid ; Glutamate Decarboxylase ; Humans ; Immobilization ; Immunohistochemistry ; Infant* ; Infant, Newborn ; N-Methylaspartate ; Prenatal Exposure Delayed Effects ; Rats* ; Seizures ; Spasm* ; Spasms, Infantile

Although the etiology of moyamoya disease (MMD) remains unknown, autoimmunity is one of the proposed pathogeneses. Unlike other autoimmune disorders that are associated with cerebral arteritis, concurrence of MMD and diabetes mellitus (DM) is rare. However, we encountered a patient with concurrent diabetic ketoacidosis (DKA) and acute ischemic stroke due to MMD. Our patient was diagnosed with glutamic acid decarboxylase antibody-positive type 2 DM (T2DM) based on laboratory and physical examination findings. Brain magnetic resonance images revealed an acute ischemic stroke in the left cerebral hemisphere and bilateral diffuse stenosis/occlusion in the middle cerebral artery and multiple collaterals. Thus, here, we report a patient with both T2DM and MMD who developed an acute ischemic stroke that was complicated by DKA.
Arteritis ; Autoimmunity ; Brain ; Cerebrum ; Diabetes Mellitus ; Diabetes Mellitus, Type 2 ; Diabetic Ketoacidosis* ; Glutamate Decarboxylase ; Humans ; Middle Cerebral Artery ; Moyamoya Disease* ; Physical Examination ; Stroke*

The visual system plays an important role in our daily life. In this study, we found that loss of dendritic cell factor 1 (DCF1) in the primary visual cortex (V1) caused a sight deficit in mice and induced an abnormal increase in glutamic acid decarboxylase 67, an enzyme that catalyzes the decarboxylation of glutamate to gamma aminobutyric acid and CO, particularly in layer 5. In vivo electrophysiological recordings confirmed a decrease in delta, theta, and beta oscillation power in DCF1-knockout mice. This study presents a previously unknown function of DCF1 in V1, suggests an unknown contact between DCF1 and GABA systems, and provides insight into the mechanism and treatment of visual deficits.
Animals ; Brain Waves ; genetics ; Disease Models, Animal ; Electroencephalography ; Gene Expression Regulation ; drug effects ; genetics ; Geniculate Bodies ; drug effects ; metabolism ; Ginkgolides ; therapeutic use ; Glutamate Decarboxylase ; metabolism ; Lactones ; therapeutic use ; Membrane Proteins ; deficiency ; genetics ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Nerve Tissue Proteins ; deficiency ; genetics ; Photic Stimulation ; Proto-Oncogene Proteins c-fos ; metabolism ; Vision Disorders ; drug therapy ; genetics ; pathology ; physiopathology ; Visual Cortex ; metabolism ; pathology ; gamma-Aminobutyric Acid ; metabolism

Sinomenium acutum has been long used in the preparations of traditional medicine in Japan, China and Korea for the treatment of various disorders including rheumatism, fever, pulmonary diseases and mood disorders. Recently, it was reported that Sinomenium acutum, has sedative and anxiolytic effects mediated by GABA-ergic systems. These experiments were performed to investigate whether sinomenine (SIN), an alkaloid derived from Sinomenium acutum enhances pentobarbital-induced sleep via γ-aminobutyric acid (GABA)-ergic systems, and modulates sleep architecture in mice. Oral administration of SIN (40 mg/kg) markedly reduced spontaneous locomotor activity, similar to diazepam (a benzodiazepine agonist) in mice. SIN shortened sleep latency, and increased total sleep time in a dose-dependent manner when co-administrated with pentobarbital (42 mg/kg, i.p.). SIN also increased the number of sleeping mice and total sleep time by concomitant administration with the sub-hypnotic dosage of pentobarbital (28 mg/kg, i.p.). SIN reduced the number of sleep-wake cycles, and increased total sleep time and non-rapid eye movement (NREM) sleep. In addition, SIN also increased chloride influx in the primary cultured hypothalamic neuronal cells. Furthermore, protein overexpression of glutamic acid decarboxylase (GAD(65/67)) and GABA(A) receptor subunits by western blot were found, being activated by SIN. In conclusion, SIN augments pentobarbital-induced sleeping behaviors through GABA(A)-ergic systems, and increased NREM sleep. It could be a candidate for the treatment of insomnia.
Administration, Oral ; Animals ; Anti-Anxiety Agents ; Benzodiazepines ; Blotting, Western ; China ; Diazepam ; Eye Movements* ; Fever ; Glutamate Decarboxylase ; Japan ; Korea ; Lung Diseases ; Medicine, Traditional ; Mice ; Mood Disorders ; Motor Activity ; Neurons ; Pentobarbital ; Receptors, GABA-A ; Rheumatic Diseases ; Rodentia* ; Sinomenium* ; Sleep Initiation and Maintenance Disorders

It has been known that RA, one of major constituents of Perilla frutescens which has been used as a traditional folk remedy for sedation in oriental countries, shows the anxiolytic-like and sedative effects. This study was performed to know whether RA may enhance pentobarbital-induced sleep through γ-aminobutyric acid (GABA)(A)-ergic systems in rodents. RA (0.5, 1.0 and 2.0 mg/kg, p.o.) reduced the locomotor activity in mice. RA decreased sleep latency and increased the total sleep time in pentobarbital (42 mg/kg, i.p.)-induced sleeping mice. RA also increased sleeping time and number of falling sleep mice after treatment with sub-hypnotic pentobarbital (28 mg/kg, i.p.). In electroencephalogram (EEG) recording, RA (2.0 mg/kg) not only decreased the counts of sleep/wake cycles and REM sleep, but also increased the total and NREM sleep in rats. The power density of NREM sleep showed the increase in δ-waves and the decrease in α-waves. On the other hand, RA (0.1, 1.0 and 10 μg/ml) increased intracellular Cl− influx in the primary cultured hypothalamic cells of rats. RA (p.o.) increased the protein expression of glutamic acid decarboxylase (GAD(65/67) ) and GABA(A) receptors subunits except β1 subunit. In conclusion, RA augmented pentobarbital-induced sleeping behaviors through GABA(A)-ergic transmission. Thus, it is suggested that RA may be useful for the treatment of insomnia.
Accidental Falls ; Animals ; Electroencephalography ; Eye Movements* ; Glutamate Decarboxylase ; Hand ; Hypnotics and Sedatives ; Medicine, Traditional ; Mice ; Motor Activity ; Pentobarbital ; Perilla frutescens ; Rats ; Receptors, GABA-A ; Rodentia ; Sleep Initiation and Maintenance Disorders ; Sleep, REM