Pingming Qiu

Caspase-11 plays an essential role in methamphetamine-induced dopaminergic neuron apoptosis.

Methamphetamine (METH) is an extremely addictive stimulant drug that is widely used with high potential of abuse. Previous studies have shown that METH exposure damages the nervous system, especially dopaminergic neurons. However, the exact molecular mechanisms of METH-induced neurotoxicity remain unclear. We hypothesized that caspase-11 is involved in METH-induced neuronal apoptosis. We tested our hypothesis by examining the change of caspase-11 protein expression in dopaminergic neurons (PC12 and SH-SY5Y) and in the midbrain of rats exposed to METH with Western blotting. We also determined the effects of blocking caspase-11 expression with wedelolactone (a specific inhibitor of caspase-11) or siRNA on METH-induced apoptosis in PC12 cells and SH-SY5Y cells using Annexin V and TUNEL staining. Furthermore, we observed the protein expression changes of the apoptotic markers, cleaved caspase-3 and cleaved poly(ADP-ribose) polymerase 1 (PARP), after silencing the caspase-11 expression in rat midbrain by injecting LV-shcasp11 lentivirus using a stereotaxic positioning system. Results showed that METH exposure increased caspase-11 expression both in vitro and in vivo, with the effects in vitro being dose- and time-dependent. Inhibition of caspase-11 expression with either wedelolactone or siRNAs reduced the number of METH-induced apoptotic cells. In addition, blocking caspase-11 expression inhibited METH-induced activation of caspase-3 and PARP in vitro and in vivo, suggesting that caspase-11/caspase-3 signal pathway is involved in METH-induced neurotoxicity. These results indicate that caspase-11 plays an essential role in METH-induced neuronal apoptosis and may be a potential gene target for therapeutics in METH-caused neurotoxicity.

RNA interference targeting α-synuclein attenuates methamphetamine-induced neurotoxicity in SH-SY5Y cells.

The protein α-synuclein (α-syn) is abundant in neurons and has been claimed to play critical roles in the pathophysiology of Parkinsons disease. Overexpression of α-syn has been shown to be toxicity in methamphetamine (METH)-induced model in vivo and in vitro which has Parkinsons-like pathology. However, the exact mechanisms underlying toxicity of α-syn mediated METH-induced neuron remain unknown. In the present study, human dopaminergic-like neuroblastoma SH-SY5Y cells were used as METH-induced model in vitro. Cell viability was found to be dramatically increased after silencing α-syn expression followed by METH treatment compared with a-syn wild-type cells and the morphological damage to cells after METH treatment was abated through knockdown of α-syn expression in this model. The expression levels of tyrosine hydroxylase (TH), dopamine transporter (DAT) and vesicular monoamine transporter 2(VMAT-2) were significantly decreased and the activity/levels of reactive oxygen species (ROS), nitric oxide synthase (NOS) and nitrogen (NO) were notably increased after METH treatment. However, the changes of these expression levels were reversed in cells transfected with α-syn-shRNA. These results suggested that TH, DAT, VMAT-2, ROS and NOS maybe involved in α-syn mediated METH-induced neuronal toxicity.

S-nitrosylating protein disulphide isomerase mediates α-synuclein aggregation caused by methamphetamine exposure in PC12 cells

Methamphetamine (METH) belongs to Amphetamine-type stimulants, METH abusers are at high risk of neurodegenerative disorders, including Parkinsons disease (PD). However, there are still no effective treatments to METH-induced neurodegeneration because its mechanism remains unknown. In order to investigate METHs neurotoxic mechanism, we established an in vitro PD pathology model by exposing PC12 cells to METH. We found the expression of nitric oxide synthase (NOS), nitric oxide (NO) and α-synuclein (α-syn) was significantly increased after METH treatment for 24h, in addition, the aggregattion of α-syn and the S-nitrosylation of protein disulphideisomerase(PDI) were also obviously enhanced. When we exposed PC12 cells to the NOS inhibitor N-nitro-L-arginine(L-NNA) with METH together, the L-NNA obviously inhibited these changes induced by METH. While when we exposed PC12 cells to the precursor of NO L-Arginine together with METH, the L-Arginine resulted in the opposite effect compared to L-NNA. And when we knocked down the PDI gene, the L-NNA did not have this effect. Therefore, PDI plays a significant role in neurological disorders related to α-syn aggregation, and it suggests that PDI could be as a potential target to prevent METH-induced neurodegeneration.

Up-regulation of protein tyrosine nitration in methamphetamine-induced neurotoxicity through DDAH/ADMA/NOS pathway

Protein tyrosine nitration is an important post-translational modification mediated by nitric oxide (NO) associated oxidative stress, occurring in a variety of neurodegenerative diseases. In our previous study, an elevated level of dimethylarginine dimethylaminohydrolase 1 (DDAH1) protein was observed in different brain regions of acute methamphetamine (METH) treated rats, indicating the possibility of an enhanced expression of protein nitration that is mediated by excess NO through the DDAH1/ADMA (Asymmetric Dimethylated l-arginine)/NOS (Nitric Oxide Synthase) pathway. In the present study, proteomic methods, including stable isotope labeling with amino acids in cell culture (SILAC) and two dimensional electrophoresis, were used to determine the relationship between protein nitration and METH induced neurotoxicity in acute METH treated rats and PC12 cells. We found that acute METH administration evokes a positive activation of DDAH1/ADMA/NOS pathway and results in an over-production of NO in different brain regions of rat and PC12 cells, whereas the whole signaling could be repressed by DDAH1 inhibitor N(ω)-(2-methoxyethyl)-arginine (l-257). In addition, enhanced expressions of 3 nitroproteins were identified in rat striatum and increased levels of 27 nitroproteins were observed in PC12 cells. These nitrated proteins are key factors for Cdk5 activation, cytoskeletal structure, ribosomes function, etc. l-257 also displayed significant protective effects against METH-induced protein nitration, apoptosis and cell death. The overall results illustrate that protein nitration plays a significant role in the acute METH induced neurotoxicity via the activation of DDAH1/ADMA/NOS pathway.

Protective effect of alpha-synuclein knockdown on methamphetamine-induced neurotoxicity in dopaminergic neurons

The over-expression of α-synuclein is a major factor in the death of dopaminergic neurons in a methamphetamine-induced model of Parkinsons disease. In the present study, α-synuclein knockdown rats were created by injecting α-synuclein-shRNA lentivirus stereotaxically into the right striatum of experimental rats. At 2 weeks post-injection, the rats were injected intraperitoneally with methamphetamine to establish the model of Parkinsons disease. Expression of α-synuclein mRNA and protein in the right striatum of the injected rats was significantly downregulated. Food intake and body weight were greater in α-synuclein knockdown rats, and water intake and stereotyped behavior score were lower than in model rats. Striatal dopamine and tyrosine hydroxylase levels were significantly elevated in α-synuclein knockdown rats. Moreover, superoxide dismutase activity was greater in α-synuclein knockdown rat striatum, but the levels of reactive oxygen species, malondialdehyde, nitric oxide synthase and nitrogen monoxide were lower compared with model rats. We also found that α-synuclein knockdown inhibited methamphetamine-induced neuronal apoptosis. These results suggest that α-synuclein has the capacity to reverse methamphetamine-induced apoptosis of dopaminergic neurons in the rat striatum by inhibiting oxidative stress and improving dopaminergic system function.

Polymorphism analysis of 15 STR loci in a large sample of Guangdong (Southern China) Han population

AmpFℓSTR Sinofiler PCR Amplification Kit is specially developed for Chinese forensic laboratories, but there are little population-genetic data about this kit for Southern China. This kit contains 15 STR loci: D8S1179, D21S11, D7S820, CSF1PO, D3S1358, D13S317, D16S539, D2S1338, D19S433, vWA, D18S51, D6S1043, D12S391, D5S818 and FGA. We have conducted genotyping experiments on the 15 STR loci in 5234 unrelated individuals from Guangdong (Southern China). We observed a total of 243 alleles in the group with the allelic frequency values ranging from less than 0.0001 to 0.3686. Our statistic analysis indicates that the 15 STR loci conform to the Hardy-Weinbergs equilibrium (p>0.05). The highest polymorphism was found at D6S1043 locus and the lowest was found at D3S1358. The combined power of discrimination reached 0.99999999999999999977431 and the combined probability of paternity exclusion reached 0.999999721 for 15 STR loci. Guangdong Han population had significant differences compared with Shaanxi, Shandong and Henan province of Northern China. A Neighbor-joining tree indicates that the Guangdong Han has a close genetic relationship with the Yunnan population. Significant differences were found between Guangdong Han population and other reported populations (Japanese, Philippine, African American, Caucasian, Hispanic and Western Romanian) at 2-11 STR loci. The results may provide useful information for forensic sciences and population genetics studies. The present findings indicate that all the 15 STR loci are highly genetically polymorphic in the Han population of Guangdong.

Genetic polymorphism of 21 non-CODIS STR loci for Guangdong (Southern China) Han population

We investigated the allelic frequencies and forensic parameters of 21 non-combined DNA index system (CODIS) short tandem repeat (STR) loci (i.e. D6S474, D12ATA63, D22S1045, D10S1248, D1S1677, D11S4463, D1S1627, D3S4529, D2S441, D6S1017, D4S2408, D19S433, D17S1301, D1GATA113, D18S853, D20S482, D14S1434, D9S1122, D2S1776, D10S1435 and D5S2500) among 506 unrelated healthy Han Chinese individuals living in Guangdong Province using a commercially available AGCU 21 + 1 STR fluorescence assay kit (AGCU ScienTech Incorporation, Wuxi, Jiangsu, China) [1]. Guangdong Province is located at the southern tip of the mainland China coast. It lies south of the Nan Mountains, the largest mountains in southern China. After three immigration climaxes of two Jin dynasties, Song dynasty and the late Ming Dynasty, a multitude of central Han Chinese entered into Guangdong Province. The current population of Guangdong Han gradually developed through long-term integration of central Han Chinese with Guangdong’s original inhabitants. Guangdong has a population of approximately 102.3 million Han and accounts for 98.02% of the province’s total population [2]. Researchers have published forensic genetic data on both different and the same ethnic groups in different geographic regions of China; however, although some data have been recorded, none have been recorded on most of the 21 non-CODIS STR loci in the Guangdong Han population. For example, De-Jian Lu et al. [3] reported data on 9 non-CODIS loci for the Guangdong population, each of which is different from the 21 non-CODIS loci. Ling Chen et al. [4] reported data on 15 loci for the Guangdong population, with only D19S433 being the same as one of 21 non-CODIS loci. A total of 506 blood samples were collected from unrelated healthy Chinese Han men (253) and women (253) living in Guangdong Province after acquiring their informed consent. DNA was directly amplified on a GeneAmp PCR 9700 thermal cycler (Thermo Fisher Scientific, Waltham, MA, USA) using a commercially available AGCU21 + 1 STR fluorescence assay kit (AGCU ScienTech Incorporation, Wuxi, Jiangsu, China) according to the manufacturer’s instructions. The PCR products were separated through capillary electrophoresis and analyzed with an ABI 3500xl Genetic Analyzer (Thermo Fisher Scientific, MA, USA) and the GeneMapper ID-X (Thermo Fisher Scientific, MA, USA). All analyses included a positive control from the 9947A DNA sample and a negative control without DNA. The allelic frequencies and forensic parameters were evaluated using PowerStat program (version 1.2) (Promega, Madison, WI, USA). The Hardy-Weinberg’s equilibrium

Inhibition of ROCK2 expression protects against methamphetamine-induced neurotoxicity in PC12 cells.

Methamphetamine is a type of psychoactive drug. It is well known that neurotoxicity caused by Methamphetamine(METH) can damage the nervous system and lead to apoptosis and cell loss of dopaminergic neurons. ROCK2 is a prominent target for gene therapy because its inhibition has proved to have a protective effect in various cell lines and pathophysiological conditions. Although several of the negative effects of METH on the dopaminergic system have been studied, the protective molecular mechanisms and the effective treatment of METH-induced apoptosis remain to be clarified. We hypothesized that ROCK2 is involved in METH-induced apoptosis. We tested our hypothesis using RT-PCR and western blotting to analyze whether silencing of ROCK2 with small interfering RNA (siROCK2) could reduce damage and apoptosis in PC12 cells after METH exposure. Increases in viability and cytomorphological changes were detected by MTT assay and bright field microscopy after pretreatment of METH-treated PC12 cells with 100 nM siROCK2. Apoptosis decreased significantly after ROCK2 silencing, as shown by Annexin V and TUNEL staining. The results show that ROCK2 is a possible gene target for therapeutics in METH-induced neurotoxicity in vitro, providing a foundation for future in vivo research.

Mutation analysis of 19 commonly used short tandem repeat loci in a Guangdong Han population

Short tandem repeats (STRs) are the most widely used genetic markers in current forensic practice. However, STR mutations have troubled paternity test all the time. To ensure the accuracy in parentage testing, it is important to obtain population mutation data and identify factors that affect STR mutation rates. In the present study, we performed a comprehensive analysis on 322 mutation events in 19 autosomal STR loci from 12,752 meiotic events in 9,626 parentage test cases. The average mutation rate for the 19 STR loci was estimated at 1.329‰ per meiosis. Most mutations were single-step and occurred in the male germline. Further, the mutation rates increased with the paternal age at child birth, but not the maternal age. Multidimensional scaling analysis showed differences in the profiles of the mutation rates of the 13 CODIS STR loci among several different worldwide populations. Our findings also showed that locus-specific mutation rates were correlated with heterozygosity, and longer alleles have higher mutation rates than shorter alleles do. The data from our study may provide useful information for parentage testing, kinship analysis, and population genetics.

A set of autosomal multiple InDel markers for forensic application and population genetic analysis in the Chinese Xinjiang Hui group

In recent years, insertion/deletion (InDel) markers have become a promising and useful supporting tool in forensic identification cases and biogeographic research field. In this study, 30 InDel loci were explored to reveal the genetic diversities and genetic relationships between Chinese Xinjiang Hui group and the 25 previously reported populations using various biostatistics methods such as forensic statistical parameter analysis, phylogenetic reconstruction, multi-dimensional scaling, principal component analysis, and STRUCTURE analysis. No deviations from Hardy-Weinberg equilibrium tests were found at all 30 loci in the Chinese Xinjiang Hui group. The observed heterozygosity and expected heterozygosity ranged from 0.1971 (HLD118) to 0.5092 (HLD92), 0.2222 (HLD118) to 0.5000 (HLD6), respectively. The cumulative probability of exclusion and combined power of discrimination were 0.988849 and 0.99999999999378, respectively, which indicated that these 30 loci could be qualified for personal identification and used as complementary genetic markers for paternity tests in forensic cases. The results of present research based on the different methods of population genetic analysis revealed that the Chinese Xinjiang Hui group had close relationships with most Chinese groups, especially Han populations. In spite of this, for a better understanding of genetic background of the Chinese Xinjiang Hui group, more molecular genetic markers such as ancestry informative markers, single nucleotide polymorphisms (SNPs), and copy number variations will be conducted in future studies.