Structural and Functional Insights into Saccharomyces cerevisiae Riboflavin Biosynthesis Reductase RIB7

Saccharomyces cerevisiae RIB7 (ScRIB7) is a potent target for anti-fungal agents because of its involvement in the riboflavin biosynthesis pathway as a NADPH-dependent reductase. However, the catalytic mechanism of riboflavin biosynthesis reductase (RBSRs) is controversial, and enzyme structure information is still lacking in eukaryotes. Here we report the crystal structure of Saccharomyces cerevisiae RIB7 at 2.10 Å resolution and its complex with NADPH at 2.35 Å resolution. ScRIB7 exists as a stable homodimer, and each subunit consists of nine central β-sheets flanked by five helices, resembling the structure of RIB7 homologues. A conserved G⁷⁶-X-G⁷⁸-X_n-G¹⁸¹-G¹⁸² motif is present at the NADPH pyrophosphate group binding site. Activity assays confirmed the necessity of Thr79, Asp83, Glu180 and Gly182 for the activity of ScRIB7. Substrate preference of ScRIB7 was altered by mutating one residue (Thr35) to a Lysine, implying that ScRIB7 Thr35 and its corresponding residue, a lysine in bacteria, are important in substrate-specific recognition.     

Low Divergence of Clonorchis sinensis in China Based on Multilocus Analysis

Clonorchis sinensis, an ancient parasite that infects a number of piscivorous mammals, attracts significant public health interest due to zoonotic exposure risks in Asia. The available studies are insufficient to reflect the prevalence, geographic distribution, and intraspecific genetic diversity of C. sinensis in endemic areas. Here, a multilocus analysis based on eight genes (ITS1, act, tub, ef-1a, cox1, cox3, nad4 and nad5 [4.986 kb]) was employed to explore the intra-species genetic construction of C. sinensis in China. Two hundred and fifty-six C. sinensis isolates were obtained from environmental reservoirs from 17 provinces of China. A total of 254 recognized Multilocus Types (MSTs) showed high diversity among these isolates using multilocus analysis. The comparison analysis of nuclear and mitochondrial phylogeny supports separate clusters in a nuclear dendrogram. Genetic differentiation analysis of three clusters (A, B, and C) showed low divergence within populations. Most isolates from clusters B and C are geographically limited to central China, while cluster A is extraordinarily genetically diverse. Further genetic analyses between different geographic distributions, water bodies and hosts support the low population divergence. The latter haplotype analyses were consistent with the phylogenetic and genetic differentiation results. A recombination network based on concatenated sequences showed a concentrated linkage recombination population in cox1, cox3, nad4 and nad5, with spatial structuring in ITS1. Coupled with the history record and archaeological evidence of C. sinensis infection in mummified desiccated feces, these data point to an ancient origin of C. sinensis in China. In conclusion, we present a likely phylogenetic structure of the C. sinensis population in mainland China, highlighting its possible tendency for biogeographic expansion. Meanwhile, ITS1 was found to be an effective marker for tracking C. sinensis infection worldwide. Thus, the present study improves our understanding of the global epidemiology and evolution of C. sinensis.     

Numerical Simulation of Airflow Fields in Two Typical Nasal Structures of Empty Nose Syndrome: A Computational Fluid Dynamics Study

Background

The pathogenesis of empty nose syndrome (ENS) has not been elucidated so far. Though postulated, there remains a lack of experimental evidence about the roles of nasal aerodynamics on the development of ENS.

Objective

To investigate the nasal aerodynamic features of ENS andto explore the role of aerodynamic changes on the pathogenesis of ENS.

Methods

Seven sinonasal models were numerically constructed, based on the high resolution computed tomography images of seven healthy male adults. Bilateral radical inferior/middle turbinectomy were numerically performed to mimic the typical nasal structures of ENS-inferior turbinate (ENS-IT) and ENS-middle turbinate (ENS-MT). A steady laminar model was applied in calculation. Velocity, pressure, streamlines, air flux and wall shear stress were numerically investigated. Each parameter of normal structures was compared with those of the corresponding pathological models of ENS-IT and ENS-MT, respectively.

Results

ENS-MT: Streamlines, air flux distribution, and wall shear stress distribution were generally similar to those of the normal structures; nasal resistances decreased. Velocities decreased locally, while increased around the sphenopalatine ganglion by 0.20±0.17m/s and 0.22±0.10m/s during inspiration and expiration, respectively. ENS-IT: Streamlines were less organized with new vortexes shown near the bottom wall. The airflow rates passing through the nasal olfactory area decreased by 26.27%±8.68% and 13.18%±7.59% during inspiration and expiration, respectively. Wall shear stresses, nasal resistances and local velocities all decreased.

Conclusion

Our CFD simulation study suggests that the changes in nasal aerodynamics may play an essential role in the pathogenesis of ENS. An increased velocity around the sphenopalatine ganglion in the ENS-MT models could be responsible for headache in patients with ENS-MT. However, these results need to be validated in further studies with a larger sample size and more complicated calculating models.     

Valproic Acid Treatment Inhibits Hypoxia-Inducible Factor 1α Accumulation and Protects against Burn-Induced Gut Barrier Dysfunction in a Rodent Model

Objective

Burn-induced gut dysfunction plays an important role in the development of sepsis and multiple organ dysfunction. Emerging evidence suggests that hypoxia-inducible factor-1α (HIF-1α) is critical in paracelluar barrier functions via regulating vascular endothelial growth factor (VEGF) and myosin light chain kinase (MLCK) expression. Previous studies have also demonstrated that histone deacetylase inhibitors (HDACIs) can repress HIF-1α. This study aims to examine whether valproic acid (VPA), a HDACI, protects against burn-induced gut barrier dysfunction via repressing HIF-1α-dependent upregulation of VEGF and MLCK expression.

Methods

Rats were subjected to third degree 55% TBSA burns and treated with/ without VPA (300mg/kg). Intestinal barrier dysfunction was evaluated by permeability of intestinal mucosa to fluorescein isothiocyanate (FITC)-dextran and histologic evaluation. Histone acetylation, tight junction protein zonula occludens 1 (ZO-1), VEGF, MLCK and HIF-1α were measured. In addition, CaCO₂ cells were transfected with siRNA directed against HIF-1α and were stimulated with CoCl2 (1mM) for 24 hours with/without VPA (2mM) followed by analysis of HIF-1α, MLCK, VEGF and ZO-1.

Results

Burn insults resulted in a significant increase in intestinal permeability and mucosal damage, accompanied by a significant reduction in histone acetylation, ZO-1, upregulation of VEGF, MLCK expression, and an increase in HIF-1α accumulation. VPA significantly attenuated the increase in intestinal permeability, mucosa damage, histone deacetylation and changes in ZO-1 expression. VPA also attenuated the increased VEGF, MLCK and HIF-1α protein levels. VPA reduced HIF-1α, MLCK and VEGF production and prevented ZO-1 loss in CoCl2-stimulated Caco-2 cells. Moreover, transfection of siRNA directed against HIF-1α led to inhibition of MLCK and VEGF production, accompanied by upregulation of ZO-1.

Conclusions

These results indicate that VPA can protect against burn-induced gut barrier dysfunction. These protective effects may be due to its inhibitory action on HIF-1α, leading to a reduction in intestinal VEGF and MLCK expression and minimizing ZO-1 degradation.     

A New Equation to Estimate Glomerular Filtration Rate in Chinese Elderly Population

Background

We sought to develop a new equation to estimate glomerular filtration rate (GFR) in Chinese elderly population.

Methods

A total of 668 Chinese elderly participants, including the development cohort (n = 433), the validation cohort (n = 235) were enrolled. The new equation using the generalized additive model, and age, gender, serum creatinine as predictor variables was developed and the performances was compared with the CKD-EPI equation.

Results

In the validation data set, both bias and precision were improved with the new equation, as compared with the CKD-EPI equation (median difference, −1.5 ml/min/1.73 m² vs. 7.4 ml/min/1.73 m² for the new equation and the CKD-EPI equation, [P<0.001]; interquartile range [IQR] for the difference, 16.2 ml/min/1.73 m² vs. 19.0 ml/min/1.73 m² [P<0.001]), as were accuracies (15% accuracy, 40.4% vs. 30.6% [P = 0.02]; 30% accuracy, 71.1% vs. 47.2%, [P<0.001]; 50% accuracy, 90.2% vs. 75.7%, [P<0.001]), allowing improvement in GFR categorization (GFR category misclassification rate, 37.4% vs. 53.2% [P = <0.001]).

Conclusions

A new equation was developed in Chinese elderly population. In the validation data set, the new equation performed better than the original CKD-EPI equation. The new equation needs further external validations. Calibration of the GFR referent standard to a more accurate one should be an useful way to improve the performance of GFR estimating equations.     

SRSF1-dependent alternative splicing attenuates BIN1 expression in non–small cell lung cancer

Decreased bridging integrator 1 (BIN1) expression has great significance in promoting the progression of malignant tumors. Reduced messenger RNA expression is partly due to aberrant alternative splicing (AS). However, the AS status of BIN1 and its correlation with BIN1 inactivation in non–small cell lung cancer (NSCLC) remains poorly defined. Here we reported that BIN1 inactivation was not related to DNA methylation in NSCLC. Importantly, BIN1 with exon 12A inclusion (BIN1+12A isoform), the most frequent aberrant splicing variant in tumors was also observed in NSCLC, and might be accounted for BIN1 inactivation. Furthermore, we showed that the aberrant splicing of BIN1 was under the control of serine and arginine-rich factor 1 (SRSF1) in NSCLC. In addition, colony formation assay showed that BIN1+12A isoform could abolish the tumor-inhibiting ability of BIN1 in NSCLC cells. Meanwhile, transwell, wound healing and apoptosis experiments demonstrated that the occurrence of BIN1+12A could abrogate the invasion suppressing activity and proapoptotic property of BIN1 in NSCLC. Significantly, we also found that BIN1+12A isoform neutralized the tumor-suppressing functions of BIN1 via affecting its subcellular localization. Altogether, these data revealed an aberrant splicing phenomenon which abated the expression and tumor-inhibiting activity of BIN1 in NSCLC, and the related mechanisms were associated with SRSF1.     

Protective effect of coumarin-pi against t-BHP-induced hepatotoxicity by upregulating antioxidant enzymes via enhanced Nrf2 signaling

Molecular and Cellular Biochemistry - Autism is a prevalent developmental disorder that combines repetitive behaviours, social deficits and language abnormalities. The present study aims to assess...     

RETRACTED ARTICLE: Silencing SP1 Alleviated Sevoflurane-Induced POCD Development via Cholinergic Anti-inflammatory Pathway

Neurochemical Research - Postoperative cognitive dysfunction (POCD) is a common complication induced by anesthesia or surgery, which affects the concentration, cognition and memory of patients....     

Effect of Early Normobaric Hyperoxia on Blast-Induced Traumatic Brain Injury in Rats

Neurochemical Research - Blast-induced traumatic brain injury (bTBI) is a leading cause of disability and mortality in soldiers during the conflicts in Iraq and Afghanistan. Although substantial...     

Genome Wide Identification of C2H2-Type Zinc Finger Proteins of Tomato and Expression Analysis Under Different Abiotic Stresses

In plants, C2H2-type zinc finger proteins play important roles in multiple processes, including plant growth and development, as well as biotic and abiotic responses. In the present study, based on the presence of the C2H2 domain (CX2~4CX3FX5LX2HX3~5H), 112 C2H2-type zinc finger proteins were predicted in tomato. Through gene and protein structures analyses and phylogenetic analysis, the 112 C2H2-type zinc finger proteins were divided into five subfamilies. Members of the same subfamily shared similarities in gene and protein structures, while members of different subfamilies contained different numbers of the C2H2 domain. The tissue expression pattern analysis showed that 24 C2H2-type zinc finger proteins are constitutively expressed in all tissues, indicating that they may play important roles in the growth and development of all tissues. In addition, under chilling (4 °C), heat (42 °C), high salinity (200 Mm NaCl), and osmotic (20% PEG) stresses, members of C2H2-type zinc finger family were induced to varying degrees, which suggested that these genes were involved in multiple abiotic stress responses. This study will provide theoretical basis for further research of C2H2-type zinc finger proteins in tomato.