TRIM66 reads unmodified H3R2K4 and H3K56ac to respond to DNA damage in embryonic stem cells.

Recognition of specific chromatin modifications by distinct structural domains within "reader" proteins plays a critical role in the maintenance of genomic stability. However, the specific mechanisms involved in this process remain unclear. Here we report that the PHD-Bromo tandem domain of tripartite motif-containing 66 (TRIM66) recognizes the unmodified H3R2-H3K4 and acetylated H3K56. The aberrant deletion of Trim66 results in severe DNA damage and genomic instability in embryonic stem cells (ESCs). Moreover, we find that the recognition of histone modification by TRIM66 is critical for DNA damage repair (DDR) in ESCs. TRIM66 recruits Sirt6 to deacetylate H3K56ac, negatively regulating the level of H3K56ac and facilitating the initiation of DDR. Importantly, Trim66-deficient blastocysts also exhibit higher levels of H3K56ac and DNA damage. Collectively, the present findings indicate the vital role of TRIM66 in DDR in ESCs, establishing the relationship between histone readers and maintenance of genomic stability.

Non-Fire Related Carbon Monoxide Poisoning in Sichuan, China: A 9-Year Study (2008-2016).

BACKGROUND: Carbon monoxide (CO) poisoning is one of the most important intoxications in the modern world. This study aimed to identify the characteristics of CO poisoning deaths in Sichuan province in the west of China. METHODS: Data on fatal non-fire-related carbon monoxide poisoning in Sichuan from 2008 to 2016 were obtained from the Department of Forensic Analytical Toxicology of Sichuan University and were analyzed by the month and year of registration of death, sex, age group, manner of death, source of CO, and location of CO exposure. Comparing with the previous studies carried out in Wuhan and Shanghai to identify the regional differences of CO poisoning in China. RESULTS: A total of 165 non-fire related CO poisoning cases including 237 victims were recorded. Over 90% of the victims died from accidental poisoning. Non-fire related CO poisoning occurred more frequently in winter months and was most prevalent in individuals aged between 18 and 60 yr old. Showering gas accident and coal or charcoal burning was found to be the major source of CO in accident and in suicide cases, respectively. Furthermore, significant regional differences of CO poisoning have been detected in the manner of death and the source of CO. CONCLUSION: These findings will be valuable in the targeted prevention of non-fire related CO poisoning in China.

Homicidal Paraquat Poisoning.

Paraquat poisoning usually results from suicide, occupational, or accidental exposure. Herein, we report a rare fatal case of homicidal paraquat poisoning. A 58-year-old man was poisoned by taking paraquat-mixed medicine and wearing paraquat-soaked underwear. In the absence of a history of paraquat exposure, the patient was misdiagnosed with pulmonary infection and scrotal dermatitis and died of respiratory failure 24 days after the initial exposure to paraquat. Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was applied to detect and quantify paraquat in postmortem specimens. The concentration of paraquat in postmortem specimens from high to low is lung (0.49 µg/g), brain (0.32 µg/g), kidney (0.24 µg/g), liver (0.20 µg/g), cardiac blood (0.11 µg/mL), and stomach wall (

Polymorphism study of nine SNPs associated with subjective response to alcohol in Chinese Han, Hui, Tibetan, Mongolian and Uygur populations.

Heavy alcohol drinking is a major public health problem, causing a large disease, social and economic burden in societies. Subjective response (SR) to alcohol is an intermediate characteristic of heavy drinking. A variety of candidate genes have been reported to be associated with SR to alcohol. In this study, we investigated nine single nucleotide polymorphisms (SNPs) related to SR to alcohol in healthy individuals from five Chinese ethnic groups, the Han, Hui, Tibetan, Mongolian and Uygur populations, and a total of 584 bloodstain samples were collected. The nine SNPs included four SNPs in alcohol-metabolizing genes (ADH1B, ADH1C, ALDH2 and CYP2E1*5B) and five SNPs in genes of neurobiological pathways (GABRA2, OPRM1, CHRNA3, HYKK and SLC6A4). A SNaPshot analysis method was developed to type these SNPs simultaneously, and all samples were typed successfully. Statistical analyses of the allele frequencies indicated that the frequencies of all SNPs, except for ADH1C, showed varying degrees of difference in the five studied ethnic groups. Tibetans showed the highest frequencies of risk alleles for heavy drinking at most loci. The genetic polymorphic differences found in this study revealed the variation in genetic susceptibility to heavy drinking in the studied populations.

Urinary metabonomics of rats with ketamine-induced cystitis using GC-MS spectroscopy.

Ketamine abuse has dramatically increased in recently years. With the widely application of ketamine, its side effects, especially cystitis induced by long-term use, have attracted more and more attention from the public. In the present study, we aimed to explore the potential generative mechanism of ketamine-induced cystitis by determining the endogenous metabolites at different time points after ketamine treatment. Body weight, bladder/body coefficient, urinary frequency, urinary potassium, serum IL-6, and TNF-α were determined at different time points after ketamine treatment. H&E staining was used to observe the changes of histopathology. Metabonomics was performed to determine the changes of endogenous metabolites. After 12 weeks of treatment, obvious inflammatory reaction was noticed in the KET group; the body weight and urinary potassium of the KET group were significantly lower than the NS group (P < 0.05) and other factors, such as urinary frequency, bladder/body coefficient, serum TNF-α and IL-6 were higher than the NS group (P < 0.05). A total of 30, 28, and 32 significantly changed metabolites were identified at the 1st week, 4th week and 12th week, respectively. Metabolic pathway analysis showed that different metabolic pathways were affected during the treatment process. Linoleic acid metabolism, beta-alanine metabolism, glyoxylate and dicarboxylate metabolism were only affected following long-term administration of ketamine. Those metabolic pathways may have a close relationship with cystitis induced by ketamine.

NMR characterization of weak interactions between RhoGDI2 and fragment screening hits.

BACKGROUND: The delineation of intrinsically weak interactions between novel targets and fragment screening hits has long limited the pace of hit-to-lead evolution. Rho guanine-nucleotide dissociation inhibitor 2 (RhoGDI2) is a novel target that lacks any chemical probes for the treatment of tumor metastasis. METHODS: Protein-observed and ligand-observed NMR spectroscopy was used to characterize the weak interactions between RhoGDI2 and fragment screening hits. RESULTS: We identified three hits of RhoGDI2 using streamlined NMR fragment-based screening. The binding site residues were assigned using non-uniformly sampled Cα- and Hα-based three dimensional NMR spectra. The molecular docking to the proposed geranylgeranyl binding pocket of RhoGDI2 was guided by NMR restraints of chemical shift perturbations and ligand-observed transferred paramagnetic relaxation enhancement. We further validated the weak RhoGDI2-hit interactions using mutagenesis and structure-affinity analysis. CONCLUSIONS: Weak interactions between RhoGDI2 and fragment screening hits were delineated using an integrated NMR approach. GENERAL INTERESTS: Binders to RhoGDI2 as a potential anti-cancer target have been first reported, and their weak interactions were depicted using NMR spectroscopy. Our work highlights the powerfulness and the versatility of the integrative NMR techniques to provide valuable structural insight into the intrinsically weak interactions between RhoGDI2 and the fragment screening hits, which could hardly be conceived using other biochemical techniques.

[Expression of PTEN in Myocardial Tissue in Coronary Heart Disease].

OBJECTIVE: To observe the expression of phosphatase and tensin homology deleted on chromosome ten (PTEN) in myocardial tissue in patients with coronary heart disease, and explore the relevance between the expression of PTEN and the occurrence and development of coronary heart disease. METHODS: A total of 16 death cases with pathological diagnosis of coronary heart disease were collected as experimental group, and 19 cases without myocardial lesions were selected as control group. The expression of PTEN protein and its mRNA were detected by immunohistochemistry and real-time fluorescence quantitative PCR respectively. The correlation between the expression of PTEN and the pathogenesis of coronary heart disease was analyzed. RESULTS: The expression of PTEN protein in myocardium in cases with coronary heart disease was significantly lower compared with the control group (P < 0.05). There was no statistical difference of the expression of PTEN mRNA between experimental and control group (P > 0.05). CONCLUSION: PTEN may be involved in the occurrence and development of coronary heart disease.

NMR Backbone Assignment of Large Proteins by Using (13) Cα -Only Triple-Resonance Experiments.

Nuclear magnetic resonance (NMR) is a powerful tool to interrogate protein structure and dynamics residue by residue. However, the prerequisite chemical-shift assignment remains a bottleneck for large proteins due to the fast relaxation and the frequency degeneracy of the (13) Cα nuclei. Herein, we present a covariance NMR strategy to assign the backbone chemical shifts by using only HN(CO)CA and HNCA spectra that has a high sensitivity even for large proteins. By using the peak linear correlation coefficient (LCC), which is a sensitive probe even for tiny chemical-shift displacements, we correctly identify the fidelity of approximately 92 % cross-peaks in the covariance spectrum, which is thus a significant improvement on the approach developed by Snyder and Brüschweiler (66 %) and the use of spectral derivatives (50 %). Thus, we calculate the 4D covariance spectrum from HN(CO)CA and HNCA experiments, in which cross-peaks with LCCs above a universal threshold are considered as true correlations. This 4D covariance spectrum enables the sequential assignment of a 42 kDa maltose binding protein (MBP), in which about 95 % residues are successfully assigned with a high accuracy of 98 %. Our LCC approach, therefore, paves the way for a residue-by-residue study of the backbone structure and dynamics of large proteins.