Restoration of Cdk5, TrkB and Soluble N-ethylmaleimide-Sensitive Factor Attachment Protein Receptor Proteins after Chronic Methylphenidate Treatment in Spontaneous Hypertensive Rats, a Model for Attention-Deficit Hyperactivity Disorder

OBJECTIVE: Synaptic vesicle mobilization and neurite outgrowth regulation molecules were examined in modulation of effects of methylphenidate (MPH) in Spontaneous Hypertensive Rats (SHRs), a model for attention-deficit hyperactivity disorder (ADHD). METHODS: We compared the changes in the protein expression level of Cyclin dependent kinase 5 (Cdk5) and molecular substrates of Cdk5; tropomyosin receptor kinase B (TrkB), syntaxin 1A (STX1A) and synaptosomal-associated protein 25 (SNAP25). Comparisons were made in prefrontal cortex of vehicle (distilled water i.p. for 7 days)-treated SHRs, vehicle-treated Wistar Kyoto Rats (WKYs) and MPH (2 mg/kg i.p. for 7 days) treated SHRs. RESULTS: The Cdk5 level of vehicle-treated SHRs was significantly decreased compared to the Cdk5 level of vehicle-treated WKY rats, but was restored to the expression level of vehicle-treated WKYs in MPH-treated SHR. The ratio of p25/p35 was significantly decreased in MPH-treated SHR compared to vehicle-treated SHR. Moreover, TrkB, STX1A and SNAP25 of vehicle-treated SHRs were significantly decreased compared to vehicle-treated WKY rats, but were restored to the expression level of vehicle-treated WKYs in MPH-treated SHR. CONCLUSION: The results show that Cdk5, TrkB, STX1A, and SNAP25 were involved in the modulation of MPH effects in prefrontal cortex of SHRs and play important role in treatment of ADHD.

The Relationship between the SNAP-25 Polymorphism and Omission Errors in Korean Children with Attention Deficit Hyperactivity Disorder

OBJECTIVE: This study aimed to investigate the association between the synaptosomal-associated protein 25 kDa (SNAP-25) genotype and performance on the continuous performance test (CPT) in Korean children with attention-deficit/hyperactivity disorder (ADHD). METHODS: Eighty-seven children with ADHD (mean age, 9.23±1.99 years) participated in this study. Omission errors, commission errors, reaction time, and reaction time variability on the CPT were analyzed. The single-nucleotide polymorphism (SNP) rs3746544 (1065 T>G) of SNAP-25 was genotyped to examine the association with CPT performance. RESULTS: We found significantly more omission errors on the CPT among children with the TT genotype of SNAP-25 (t=2.56, p=0.012) after correcting for multiple testing. CONCLUSION: Our results suggest the possible involvement of the SNAP-25 1065 T>G polymorphism in the inattention phenotype in children with ADHD. Further studies with more refined neuropsychological measures and much larger sample sizes are needed to confirm our findings.

Suppressing SNAP-25 and reversing glial glutamate transporters relieves neuropathic pain in rats by ameliorating imbalanced neurotransmission / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Neuropathic pain results from a lesion or disease affecting the somatosensory system at either the peripheral or central level. The transmission of nociception within the central nervous system is subject to modulation by release and reuptake of neurotransmitters, which maintain a dynamic balance through the assembly and disassembly of the SNARE complex as well as a series of neurotransmitter transporters (inhibitory GABA transporters GAT and excitatory glutamate transporters GT). Neuronal hyper-excitability or defected inhibition involved in neuropathic pain is one of the outcomes caused by imbalanced neurotransmission. SNAP-25, which is one of the SNARE complexes, can modulate the release of neurotransmitters. Glia glutamate transporter (GLT) is one of the two glutamate transporters which account for most synaptic glutamate uptake in the CNS. The role of SNAP-25 and GLT as well as GAT is not clearly understood.</p><p><b>METHODS</b>We used the rat chronic constriction injury (CCI) model for research, and degraded SNAP-25 by a single intrathecal administration of BoNT/A. The mechanical (MWT) and thermal withdrawal latency (TWL) were tested. The level of SNAP-25, GLT, and GAT-1 were assayed using RT-PCR and Western blotting.</p><p><b>RESULTS</b>SNAP-25 was suppressed by a single intrathecal administration of 0.01U BoNT/A and the reduction of SNAP- 25 was correlated with the relief of nociceptive responses in CCI rats. MWT and TWL returned to normal from the 5th to 14th day (P < 0.05) after the administration. On the 14th day after surgery, compared to the sham group, the upregulation of SNAP-25 in CCI rats was reversed after BoNT/A treatment (P < 0.05). The decreased GLT was reversed after BoNT/A treatment but increased GAT-1 was not influenced by BoNT/A treatment.</p><p><b>CONCLUSIONS</b>SNAP-25 and GLT play important roles in the development of neuropathic pain, and the mechanism may involve the imbalance of neurotransmission after peripheral nerve injury. Intrathecal administration of BoNT/A reversed the upregulation of SNAP-25 and downregulation of GLT after CCI, but had no significant effect on the expression of GAT-1.</p>

LRRK2 phosphorylates Snapin and inhibits interaction of Snapin with SNAP-25

Leucine-rich repeat kinase 2 (LRRK2) is a gene that, upon mutation, causes autosomal-dominant familial Parkinson's disease (PD). Yeast two-hybrid screening revealed that Snapin, a SNAP-25 (synaptosomal-associated protein-25) interacting protein, interacts with LRRK2. An in vitro kinase assay exhibited that Snapin is phosphorylated by LRRK2. A glutathione-S-transferase (GST) pull-down assay showed that LRRK2 may interact with Snapin via its Ras-of-complex (ROC) and N-terminal domains, with no significant difference on interaction of Snapin with LRRK2 wild type (WT) or its pathogenic mutants. Further analysis by mutation study revealed that Threonine 117 of Snapin is one of the sites phosphorylated by LRRK2. Furthermore, a Snapin T117D phosphomimetic mutant decreased its interaction with SNAP-25 in the GST pull-down assay. SNAP-25 is a component of the SNARE (Soluble NSF Attachment protein REceptor) complex and is critical for the exocytosis of synaptic vesicles. Incubation of rat brain lysate with recombinant Snapin T117D, but not WT, protein caused decreased interaction of synaptotagmin with the SNARE complex based on a co-immunoprecipitation assay. We further found that LRRK2-dependent phosphorylation of Snapin in the hippocampal neurons resulted in a decrease in the number of readily releasable vesicles and the extent of exocytotic release. Combined, these data suggest that LRRK2 may regulate neurotransmitter release via control of Snapin function by inhibitory phosphorylation.

Prioritization of candidate genes for attention deficit hyperactivity disorder by computational analysis of multiple data sources

Attention deficit hyperactivity disorder (ADHD) is a common, highly heritable psychiatric disorder characterized by hyperactivity, inattention and increased impulsivity. In recent years, a large number of genetic studies for ADHD have been published and related genetic data has been accumulated dramatically. To provide researchers a comprehensive ADHD genetic resource, we previously developed the first genetic database for ADHD (ADHDgene). The abundant genetic data provides novel candidates for further study. Meanwhile, it also brings new challenge for selecting promising candidate genes for replication and verification research. In this study, we surveyed the computational tools for candidate gene prioritization and selected five tools, which integrate multiple data sources for gene prioritization, to prioritize ADHD candidate genes in ADHDgene. The prioritization analysis resulted in 16 prioritized candidate genes, which are mainly involved in several major neurotransmitter systems or in nervous system development pathways. Among these genes, nervous system development related genes, especially SNAP25, STX1A and the gene-gene interactions related with each of them deserve further investigations. Our results may provide new insight for further verification study and facilitate the exploration of pathogenesis mechanism of ADHD.

Lead impairs ability of learning and memory and affects expression of synaptosomal-associated protein-25 in hippocampus of offspring / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To find the effects of lead taken by pregnant mice on learning and memory and the expression of synaptosomal-associated protein (SNAP)-25 mRNA and protein, in order to reveal the mechanism of neurotoxicity induced by lead.</p><p><b>METHODS</b>Lead exposure was conducted through freely drinking the corresponding lead acetate solutions with dosages of 0.3, 1.0, 3.0 g/L respectively. Each group was composed of 10 mice. 7, 14 and 21 days after their birth. The lead contents in blood and hippocampus of the offspring were determined. At the 21st day the expression of SNAP-25 mRNA and protein in hippocampus of all the offspring in various dosages groups were determined by RT-PCR and immunohistochemistry assay.</p><p><b>RESULTS</b>The lead contents in blood and hippocampus of various lead exposed groups were significantly higher than those of the control group (P < 0.05). The lead levels in blood and hippocampus changed accordingly to the days of growth. In Water Morris Maze experiment, the result of 0.3 g/L group was not significantly different from that of the control group (P > 0.05), however, the results of 1.0, 3.0 g/L groups (5.89 ± 0.54, 9.53 ± 1.03) were significantly different from those of the control group (1.73 ± 0.07) (P < 0.05, P < 0.01). The expression of SNAP-25 mRNA and protein was lower in lead exposed groups than that of the control group (P < 0.05).</p><p><b>CONCLUSION</b>Maternal lead exposure may induce the damage in the ability of learning and memory of the offspring. The neurotoxicity of lead may be induced by decreasing the expression of SNAP-25 mRNA and protein so as to affect the release of neurotransmitter from presynaptic terminal resulted in nerve damages.</p>

Relationship between neuronal restricted silencing factor and induced differentiation from rat mesenchymal stem cells to neurons / 中国医学科学院学报

<p><b>OBJECTIVE</b>To analyze the change of the neuronal restricted silencing factor (NRSF) gene as well as the NRSF regulation genes in beta-mercaptoethanol induction of the marrow mesenchymal stem cells (MSCs) to neurons, and to discuss the function of NRSF in neural induction of the MSCs and the mechanism of the differentiation from MSCs to neurons.</p><p><b>METHOD</b>We used beta-mercaptoethanol, serum-free DMEM, and dimethyl sulfoxide to induce rat MSCs to differentiate to neurons, and then analyzed the changes of the expressions of NRSF gene and NRSF-regulated genes through real-time PCR.</p><p><b>RESULTS</b>The rat MSCs were successfully induced to differentiate into neuron-like cells. The induced neuron marker, neuron-specific enolase, was positive. Real-time PCR showed that the expression of NRSF gene remarkably declined. The expressions of neurotrophic tyrosine kinase receptor, type 3, synaptosomal-associated protein 25, L1 cell adhesion molecular,neuronal pentraxin receptor in the NRSF-regulated genes also increased at varied extents.</p><p><b>CONCLUSIONS</b>The differentiation from MSCs to neurons is relevant with the decline of NRSF expression and the increase of the expressions of NRSF-regulated genes. The NRSF may be the key gene during the differentiation from MSCs to neurons.</p>

Association of 14 polymorphisms in the five candidate genes and attention deficit hyperactivity disorder / 中国当代儿科杂志

<p><b>OBJECTIVE</b>Attention deficit hyperactivity disorder (ADHD) is one of the most common behavior disorders in childhood and adolescent. The etiology of ADHD is unknown. The aim of this study was to investigate the relationship between each of the 14 polymorphisms in the five candidate genes and ADHD, and between the combination of some polymorphisms in those genes and ADHD, in attempting to examine whether combinations of genotypes would confer a significant susceptibility to ADHD.</p><p><b>METHODS</b>One hundred and thirty-nine children with ADHD and one hundred and nineteen normal children were enrolled. Eight single nucleotide polymorphisms (SNP) of three candidate genes were examined with PCR and RFLP techniques. 48 bp VNTR in DRD4 gene was examined with PCR, nondenaturing polyacrylamide gel electrophoresis and silver staining. Five microsatellites (MS) of three candidate genes were examined with genotyping. The relationship between the combinations of 12 polymorphisms and ADHD was examined with logistic regression analysis.</p><p><b>RESULTS</b>1.The frequency of 1065T/1065T genotype and the 1065T allele were significantly higher in ADHD children than that in normal controls (P<0.05). The frequency of -48G/-48G genotype of the A-48G polymorphism of DRD1 gene was significantly lower in ADHD children than that in normal controls (P<0.05). 2. A specific combination of three polymorphisms in the two genes showing an association with ADHD gave a prediction level of 77.5%.</p><p><b>CONCLUSIONS</b>The T1065G polymorphism in the SNAP-25 may be associated with ADHD. The 1065T/1065T genotype and the 1065T allele may be a risk factor for ADHD. The A-48G polymorphism of DRDI may be associated with ADHD. The -48G/-48G genotype may be a protective factor for ADHD. The specific combination of three sites of SNP in SNAP-25 gene and DRDI gene is found and shows an association with ADHD in 12 polymorphisms of the five candidate genes on glutamatergic/dopaminergic pathway.</p>

Association between SNAP-25 gene polymorphism and attention deficit hyperactivity disorder / 中华儿科杂志

<p><b>OBJECTIVE</b>To analyse the association between polymorphism in human synaptosomal-associated protein of 25 000 (SNAP-25) gene and attention deficit hyperactivity disorder (ADHD) in Han Chinese children.</p><p><b>METHODS</b>The study samples were comprised of 100 integrated ADHD trios (included proband and biological parents) and 97 unrelated controls. Association of polymorphism with ADHD and its subtype was examined by: (1) comparing cases and controls; (2) using family-based association study in transmission disequilibrium test (TDT).</p><p><b>RESULTS</b>Case-control analysis of short tandem repeat (STR) showed that there was no significant difference between the two groups in allele gene frequency and genotype frequency (P > 0.05); TDT analysis of the rs363006 SNP and the rs362549 SNP revealed no association between SNAP-25 polymorphisms and ADHD (P > 0.05). But after a stratification by ADHD subtype, the rs362549 SNP A allele showed a tendency to preferentially transmitted to ADHD-I subtype (chi(2) = 8.00, P < 0.01); and the rs362549 SNP G allele had a tendency to preferentially transmitted to ADHD-C subtype (chi(2) = 4.122, P < 0.05).</p><p><b>CONCLUSIONS</b>No association was found between SNAP-25 polymorphisms and ADHD. There was a possible association between rs362549 SNP polymorphism and ADHD subtypes, but the findings require replication before drawing a definitive conclusion.</p>