The clinical application value of gonadotropin-releasing hormone antagonist combined with low-dose HCG regimen in patients with ovarian hyper-stimulation based on clinical characteristics and laboratory indicators.

OBJECTIVE: To explore the clinical application value of gonadotropin-releasing hormone antagonist (GnRH-A) combined with low-dose HCG regimen in patients with high ovarian response based on clinical characteristics and laboratory indicators. METHODS: The clinical data of 305 patients who received IVF/ICSI in the Hechi People's Hospital Reproductive Medicine Center from March 2018 to December 2021 were retrospectively included, and all patients were treated with GnRH-A combined with low-dose HCG regimen protocol. The patients were separated into an ovarian hyper-response group and a normal ovarian reaction group according to their ovarian reactivity. Risk factors for ovarian hyper-response in IVF/ICSI patients were screened by univariate and multivariate logistic analysis. The ROC curve area was used to evaluate the prediction effect. RESULTS: Of the 305 patients, 6 (1.97%) had poor ovarian reaction, 123 (40.33%) had ovarian hyper response, and 176 (57.70%) had normal ovarian reaction. The proportion of ovarian hyper response and normal ovarian reaction was 98.03% (299/305); the basic serum FSH level, AMH level, E2 on HCG level on HCG injection day and the incidence of moderate to severe OHSS in the Ovarian hyper-response group were compared with those in the normal ovarian reaction group (P < 0.05). Logistic reversion analysis showed that AMH (OR = 1.246, 95% CI = 1.107-1.402), E2 level on HCG injection day (OR = 1.050, 95% CI = 1.028-1.072) and P level on HCG injection day (OR = 5.831, 95% CI = 1.231-27.616) were factors for ovarian hyper response. Basal serum FSH (OR = 0.781, 95% CI = 0.647-0.94) and LH level on HCG injection day (OR = 0.594, 95% CI = 0.405-0.871) were negatively correlated with the occurrence of high response (P < 0.05). ROC curve analysis showed that AMH (AUC = 0.779), E2 level on HCG injection day (AUC = 0.802), P level on HCG injection day (AUC = 0.636), combined detection (AUC = 0.843), AUC > 0.5. Among them, the prediction effect of joint detection is better. CONCLUSION: GnRH-A combined with low-dose HCG regimen is feasible for patients with ovarian hyper-response during IVF-ET/ICSI, and does not affect the implantation rate, clinical pregnancy rate, live birth rate, and early abortion rate of such patients. Combined detection of basal serum FSH, AMH, LH, E2 and P levels on HCG injection day can effectively predict the occurrence of ovarian hyper-response.

A histone H3K4me1-specific binding protein is required for siRNA accumulation and DNA methylation at a subset of loci targeted by RNA-directed DNA methylation.

In plants, RNA-directed DNA methylation (RdDM) is a well-known de novo DNA methylation pathway that involves two plant-specific RNA polymerases, Pol IV and Pol V. In this study, we discovered and characterized an RdDM factor, RDM15. Through DNA methylome and genome-wide siRNA analyses, we show that RDM15 is required for RdDM-dependent DNA methylation and siRNA accumulation at a subset of RdDM target loci. We show that RDM15 contributes to Pol V-dependent downstream siRNA accumulation and interacts with NRPE3B, a subunit specific to Pol V. We also show that the C-terminal tudor domain of RDM15 specifically recognizes the histone 3 lysine 4 monomethylation (H3K4me1) mark. Structure analysis of RDM15 in complex with the H3K4me1 peptide showed that the RDM15 tudor domain specifically recognizes the monomethyllysine through an aromatic cage and a specific hydrogen bonding network; this chemical feature-based recognition mechanism differs from all previously reported monomethyllysine recognition mechanisms. RDM15 and H3K4me1 have similar genome-wide distribution patterns at RDM15-dependent RdDM target loci, establishing a link between H3K4me1 and RDM15-mediated RdDM in vivo. In summary, we have identified and characterized a histone H3K4me1-specific binding protein as an RdDM component, and structural analysis of RDM15 revealed a chemical feature-based lower methyllysine recognition mechanism.

Loss of APJ mediated ß-arrestin signalling improves high-fat diet induced metabolic dysfunction but does not alter cardiac function in mice.

Apelin receptor (APJ) is a G protein-coupled receptor that contributes to many physiological processes and is emerging as a therapeutic target to treat a variety of diseases. For most disease indications the role of G protein vs ß-arrestin signalling in mitigating disease pathophysiology remains poorly understood. This hinders the development of G protein biased APJ agonists, which have been proposed to have several advantages over balanced APJ signalling agonists. To elucidate the contribution of APJ ß-arrestin signalling, we generated a transgenic mouse harbouring a point mutation (APJ I107A) that maintains full G protein activity but fails to recruit ß-arrestin following receptor activation. APJ I107A mutant mice did not alter cardiac function at rest, following exercise challenge or in response to pressure overload induced cardiac hypertrophy. Additionally, APJ I107A mice have comparable body weights, plasma glucose and lipid levels relative to WT mice when fed a chow diet. However, APJ I107A mice showed significantly lower body weight, blood insulin levels, improved glucose tolerance and greater insulin sensitivity when fed a high-fat diet. Furthermore, loss of APJ ß-arrestin signalling also affected fat composition and the expression of lipid metabolism related genes in adipose tissue from high-fat fed mice. Taken together, our results suggest that G protein biased APJ activation may be more effective for certain disease indications given that loss of APJ mediated ß-arrestin signalling appears to mitigate several aspects of diet induced metabolic dysfunction.

GPCR structure and function relationship: identification of a biased apelin receptor mutant.

Biased ligands of G protein-coupled receptors (GPCRs) may have improved therapeutic benefits and safety profiles. However, the molecular mechanism of GPCR biased signaling remains largely unknown. Using apelin receptor (APJ) as a model, we systematically investigated the potential effects of amino acid residues around the orthosteric binding site on biased signaling. We discovered that a single residue mutation I109A (I1093.32) in the transmembrane domain 3 (TM3) located in the deep ligand-binding pocket was sufficient to convert a balanced APJ into a G protein signaling biased receptor. APJ I109A mutant receptor retained full capabilities in ligand binding and G protein activation, but was defective in GRK recruitment, ß-arrestin recruitment, and downstream receptor-mediated ERK activation. Based on molecular dynamics simulations, we proposed a molecular mechanism for biased signaling of I109A mutant receptor. We postulate that due to the extra space created by I109A mutation, the phenyl group of the last residue (Phe-13) of apelin rotates down and initiates a cascade of conformational changes in TM3. Phe-13 formed a new cluster of hydrophobic interactions with the sidechains of residues in TM3, including F1103.33 and M1133.36, which stabilizes the mutant receptor in a conformation favoring biased signaling. Interruption of these stabilizing interactions by double mutation F110A/I109A or M113A/I109A largely restored the ß-arrestin-mediated signaling. Taken together, we describe herein the discovery of a biased APJ mutant receptor and provide detailed molecular insights into APJ signaling selectivity, facilitating the discovery of novel therapeutics targeting APJ.

Different Eukaryotic Initiation Factor 2Bε Mutations Lead to Various Degrees of Intolerance to the Stress of Endoplasmic Reticulum in Oligodendrocytes.

BACKGROUND: Vanishing white matter disease (VWM), a human autosomal recessive inherited leukoencephalopathy, is due to mutations in eukaryotic initiation factor 2B (eIF2B). eIF2B is responsible for the initiation of protein synthesis by its guanine nucleotide exchange factor (GEF) activity. Mutations of eIF2B impair GEF activity at different degree. Previous studies implied improperly activated unfolded protein response (UPR) and endoplasmic reticulum stress (ERS) participated in the pathogenesis of VWM. Autophagy relieves endoplasmic reticulum load by eliminating the unfolded protein. It is still unknown the effects of genotypes on the pathogenesis. In this work, UPR and autophagy flux were analyzed with different mutational types. METHODS: ERS tolerance, reflected by apoptosis and cell viability, was detected in human oligodendrocyte cell line transfected with the wild type, or different mutations of p. Arg113His, p. Arg269FNx01 or p. Ser610-Asp613del in eIF2Bε. A representative UPR-PERK component of activating transcription factor 4 (ATF4) was measured under the basal condition and ERS induction. Autophagy was analyzed the flux in the presence of lysosomal inhibitors. RESULTS: The degree of ERS tolerance varied in different genotypes. The truncated or deletion mutant showed prominent apoptosis cell viability declination after ERS induction. The most seriously damaged GEF activity of p. Arg269FNx01 group underwent spontaneous apoptosis. The truncated or deletion mutant showed elevated ATF4 under basal as well as ERS condition. Decreased expression of LC3-I and LC3-II in the mutants reflected an impaired autophagy flux, which was more obvious in the truncated or deletion mutants after ERS induction. CONCLUSIONS: GEF activities in different genotypes could influence the cell ERS tolerance as well as compensatory pathways of UPR and autophagy. Oligodendrocytes with truncated or deletion mutants showed less tolerable to ERS.

Structural mechanisms of RNA recognition: sequence-specific and non-specific RNA-binding proteins and the Cas9-RNA-DNA complex.

RNA-binding proteins play crucial roles in RNA processing and function as regulators of gene expression. Recent studies have defined the structural basis for RNA recognition by diverse RNA-binding motifs. While many RNA-binding proteins recognize RNA sequence non-specifically by associating with 5' or 3' RNA ends, sequence-specific recognition by RNA-binding proteins is typically achieved by combining multiple modular domains to form complex binding surfaces. In this review, we present examples of structures from different classes of RNA-binding proteins, identify the mechanisms utilized by them to target specific RNAs, and describe structural principles of how protein-protein interactions affect RNA recognition specificity. We also highlight the structural mechanism of sequence-dependent and -independent interactions in the Cas9-RNA-DNA complex.

Structural basis for RNA recognition by a dimeric PPR-protein complex.

Thylakoid assembly 8 (THA8) is a pentatricopeptide repeat (PPR) RNA-binding protein required for the splicing of the transcript of ycf3, a gene involved in chloroplast thylakoid-membrane biogenesis. Here we report the identification of multiple THA8-binding sites in the ycf3 intron and present crystal structures of Brachypodium distachyon THA8 either free of RNA or bound to two of the identified RNA sites. The apostructure reveals a THA8 monomer with five tandem PPR repeats arranged in a planar fold. The complexes of THA8 bound to the two short RNA fragments surprisingly reveal asymmetric THA8 dimers with the bound RNAs at the dimeric interface. RNA binding induces THA8 dimerization, with a conserved G nucleotide of the bound RNAs making extensive contacts with both monomers. Together, these results establish a new model of RNA recognition by RNA-induced formation of an asymmetric dimer of a PPR protein.

Structure of a PLS-class pentatricopeptide repeat protein provides insights into mechanism of RNA recognition.

Pentatricopeptide repeat (PPR) proteins are sequence-specific RNA-binding proteins that form a pervasive family of proteins conserved in yeast, plants, and humans. The plant PPR proteins are grouped mainly into the P and PLS classes. Here, we report the crystal structure of a PLS-class PPR protein from Arabidopsis thaliana called THA8L (THA8-like) at 2.0 Å. THA8L resembles THA8 (thylakoid assembly 8), a protein that is required for the splicing of specific group II introns of genes involved in biogenesis of chloroplast thylakoid membranes. The THA8L structure contains three P-type PPR motifs flanked by one L-type motif and one S-type motif. We identified several putative THA8L-binding sites, enriched with purine sequences, in the group II introns. Importantly, THA8L has strong binding preference for single-stranded RNA over single-stranded DNA or double-stranded RNA. Structural analysis revealed that THA8L contains two extensive patches of positively charged residues next to the residues that are proposed to comprise the RNA-binding codes. Mutations in these two positively charged patches greatly reduced THA8L RNA-binding activity. On the basis of these data, we constructed a model of THA8L-RNA binding that is dependent on two forces: one is the interaction between nucleotide bases and specific amino acids in the PPR motifs (codes), and the other is the interaction between the negatively charged RNA backbone and positively charged residues of PPR motifs. Together, these results further our understanding of the mechanism of PPR protein-RNA interactions.

[Influence of pyrrolidine dithiocarbamate (PDTC) on expression of transforming growth factor beta(1), matrix metalloproteinase-2 and tissue inhibitor-1 of metalloproteinase in rats with pulmonary damage induced by paraquat].

OBJECTIVE: To investigate the influence of pyrrolidine dithiocarbamate (PDTC) on the expression of transforming growth factor beta(1) (TGF-beta(1)), matrix metalloproteinase-2 (MMP-2) and tissue inhibitor-1 of metalloproteinase (TIMP-1) in rats with pulmonary damage induced by paraquat (PQ). METHODS: Fifty-four healthy male SD rats were randomly assigned into the control group (normal saline), the PQ-treatment groups (4 groups) and the PDTC treatment groups (4 groups). Except the rats in the control group, the rats in the PQ group were gavaged only with 40 mg/kg PQ, and PDTC group with 40 mg/kg PQ plus immediate injection 120 mg/kg PDTC (i.p). On the 3rd, the 7th, the 14th and 28th day after treatments, one group rats of each treatments were sacrificed and lung and blood samples were collected. The level of TGF-beta(1) protein in the plasma, the mRNA expression of TGF-beta(1), MMP-2 and TIMP-1 were evaluated using RT-PCR and real-time quantitative PCR, while pathological changes of lung were examined under optical microscope and electrical microscope. RESULTS: The TGF-beta(1) protein, TGF-beta(1) and MMP-2 mRNA expression were increased significantly in the earlier stage and then decreased after PQ administration (P < 0.05 or P < 0.01), while the mRNA level of TIMP-1 was augmented continuously (P < 0.01) throughout the study compared to the control group. In comparison with the PQ group, in the PDTC treatment group, the TGF-beta(1) mRNA expression on the 3rd and the 14th day, 0.54 +/- 0.08 and 0.72 +/- 0.04 respectively, the MMP-2 mRNA expression on the 7th and 14th day, 1.62 +/- 0.50 and 1.97 +/- 0.34 respective-ly, and the TIMP-1 mRNA on the 7th and 21st day, 1.79 +/- 0.21 and 2.00 +/- 0.34 respectively, were significantly decreased (P < 0.05 or P < 0.01). CONCLUSION: PDTC could attenuate paraquat-induced up-regulation of TGF-beta(1) and its mRNA expression, MMP-2 and TIMP-1 mRNA levels, which indicates that PDTC may exert its protective effects on paraquat-induced pulmonary damage by alleviating the earlier inflammation damage and adjust-ing the balance between MMPs and TIMPs. However, further studies are still warranted to investigate and clarify the underlying mechanisms involved in this complicated process.

[Effects of 90-day oral dimethoate exposure on glutamatergic system and neurobehavioral performance in rats].

OBJECTIVE: To investigate the spatial learning and exploration along with the CNS excitatory amino acid neurotransmitters profiles in adult rats subchronically exposed to the anticholinesterase organophosphorus insecticide dimethoate. METHODS: Rats were gavaged daily with dimethoate (0, 5, 10 or 20 mg/kg via oral) in NS. for 90 days. Morris water maze tasks were used to test the spatial learning and memory in the rats after the dimethoate exposure. Simultaneously, rats were decapitated for the determination of brain cholinesterase AChE activities, glutamate concentrations, and the NMDA receptor NMDA-R densities and affinities in hippocampus. RESULTS: Latencies to find a hidden escape platform were significantly longer in dimethoate dosed groups than that of the control group in the place navigation tests. Subsequently, the times of crossing the location of platform which had been removed obviously decreased in the highest dose group compared with that of the control in the spatial probe tests (P < 0.05). AChE activity was significantly reduced 42% approximately 78% by all three doses of dimethoate (P < 0.05). Glutamate concentrations were increased significantly 132.9% approximately 134.5% by the two highest doses of dimethoate (P < 0.05). In addition, the NMDA receptor bindings were reduced 21.2% approximately 23.2% with the statistical significance at the same two highest doses (P < 0.05). Furthermore, the receptor affinities was reduced 33.1% by the highest dose group (P < 0.05). The lesions of spatial memory were statistically corrected with the decrease of the NMDA-R affinities (P < 0.05). CONCLUSION: The cholinergic lesion as well as the excitatory amino acid system alteration might attribute to the inferior ability in spatial learning and memory in dimethoate subchronically exposed rats.

[Protective effects of vigabatrin and atropine against dimethoate induced-intoxication in mice].

OBJECTIVE: To investigate the protective effects of vigabatrin and atropine against the acute toxicity of dimethoate in male Kun-min mice. METHODS: The therapeutic schedules of vigabatrin (50 or 100 mg/kg) and (or) atropine (2.5 or 5.0 mg/kg) were performed according to the L(9) (3(4)) orthogonal test table. The survival time, the righting reflex and the onset of muscle fasciculations were observed after the administration of dimethoate. RESULTS: First, the main effects of vigabatrin, atropine and the interaction between them were statistically significant in the Univariate analysis of the survival time at the alpha level of 0.05 (F(V)= 4.73, P(V)= 0.015, F(A)= 50.88, P(A)= 0.000, F(VxA)= 4.17, P(VxA)= 0.007). The range of atropine was more than double of that of vigabatrin or their interaction (R(A)> 2RV or 2R(VxA)). So not only atropine and vigabatrin but also their combination interaction protected mice against dimethoate lethality. The atropine played the major role in diminishing the lethality induced by dimethoate. Second, only vigabatrin, while not atropine, delayed the mice from dimethoate-induced muscle fasciculation according its statistical results (F(V)= 6.87, P(V)= 0.003, F(A)= 0.03, P(A)= 0.968, F(VxA)= 1.134, P(VxA)= 0.356). It should be noted that vigabatrin could not completely prevent dimethoate induced-muscle fasciculation in the test. At last, both atropine and vigabatrin could maintain the righting reflex in the intoxication, however there was no interaction between them (F(V)= 5.81, P(V)= 0.006, F(A)= 9.05, P(A)= 0.001, F(VxA)= 1.34, P(VxA)= 0.257). CONCLUSION: Combined treatment with atropine and vigabatrin in the organophosphates intoxication seems reasonable and acceptable.

[Effect of dimethoate on the expression of heat shock protein 70 in peripheral blood lymphocytes of human beings].

OBJECTIVE: To study the effect of dimethoate on the expression of heat shock protein 70 (HSP70) in peripheral blood lymphocytes of human beings and to explore the feasibility of HSP70 in biomonitoring among workers exposed to organophosphorous pesticides. METHODS: Peripheral blood lymphocytes were isolated from subjects, comprising 11 people of the control group and 35 workers of the exposure group exposed to dimethoate. Flow cytometry was used for detecting both the basic level and the level of the dimethoate-induced expression of HSP70. The activity of whole blood acetylcholinesterase (AChE) was examined at the same time. Then the potential influential factors to HSP70 expression and AChE activity were analyzed. RESULTS: The basic level of HSP70 expression in the exposure group and the control group was 41.24% +/- 10.45% and 23.97% +/- 4.29% respectively. The activity of AChE in these two groups were (125.23 +/- 7.97) and (145.36 +/- 8.78) U/ml respectively. Both differences were statistically significant (P < 0.01). Among the exposure group, the basic level of HSP70 expression of the two categories comprising operators and packers, were 47.34% +/- 11.87% and 38.05% +/- 8.20% respectively (P < 0.05), while there was no significant difference (P > 0.05) in AChE activity between these two categories. The factors that had significant influence on the HSP70 basic level of the exposure group were the health condition, the environmental concentration of dimethoate and the exposure time in order, according to their significance of influence. At least 88% variance of HSP70 could be explained by these factors. The only factor that could influence AChE activity significantly was the exposure time, and it could only explain about 12% variance of AChE activity. After the treatment of dimethoate in vitro, the level of the induced expression of HSP70 in the control group was significantly higher than that of the exposure group (P < 0.01). The increasing order was the control group, the group of packers and the group of operators according to the increasing extent and there were significant difference among them (P < 0.01). The factors that could significantly influence the change ratio of HSP70 expression were the environmental concentration and the exposure time. CONCLUSION: HSP70 is a potential index that can reflect the individual and environmental conditions of workers exposed to dimethoate comprehensively.