Pax3/7BP is a Pax7- and Pax3-binding protein that regulates the proliferation of muscle precursor cells by an epigenetic mechanism

In mouse skeletal muscles, Pax7 uniquely marks muscle satellite cells and plays some important yet unknown functions at the perinatal stage. To elucidate its in vivo functions, we initiated a yeast two-hybrid screening to look for Pax7-interacting proteins and identified a previously uncharacterized Pax7- and Pax3-binding protein (Pax3/7BP). Pax3/7BP is a ubiquitously expressed nuclear protein, enriched in Pax7+ muscle precursor cells (MPCs), and serves as an indispensable adaptor for Pax7 to recruit the histone 3 lysine 4 (H3K4) methyltransferase (HMT) complex by bridging Pax7 and Wdr5. Knockdown of Pax3/7BP abolished the Pax3/7-associated H3K4 HMT activity and inhibited the proliferation of Pax7+ MPCs from young mice both in culture and in vivo. Id3 and Cdc20 were direct target genes of Pax7 and Pax3/7BP involved in the proliferation of Pax7+ MPCs. Collectively, our work establishes Pax3/7BP as an essential adaptor linking Pax3/7 with the H3K4 HMT to regulate the proliferation of MPCs.     

Phylogenetic Analysis of AA-genome Oryza Species (Poaceae) Based on Chloroplast, Mitochondrial, and Nuclear DNA Sequences

Species in the genus Oryza (Poaceae) contain 10 genomic types and are distributed in pan-tropics of the world. To explore phylogenetic relationships of Oryza species having the AA-genome, DNA sequences of the chloroplast trnL intron and trnL-trnF spacer, mitochondrial nad1 intron 2, and nuclear internal transcribed spacer were analyzed, based on materials from 6 cultivated (O. sativa and O. glaberrima) and 13 wild accessions, in addition to a CC-genome species (O. officinalis) that was used as an outgroup. Analyses of the combined sequence data set from different sources provide a much better resolution of the AA-genome species than the individual data set, indicating the limitation of a single gene in phylogenetic reconstruction. The phylogeny based on the combined data set demonstrated an apparent grouping of the AA-genome Oryza species that was well associated with their geographic origin, although the Australian O. meridionalis showed its affinity with the African species. The geographic pattern of the phylogenetic relationship was probably attributed to the frequent genetic exchange and introgression among the AA-genome species from the same continents. In addition, Asian cultivated rice O. sativa showed its close relation to O. rufipogon and O. nivara, whereas African cultivated rice O. glaberrima was closely linked to O. barthii and O. longistaminata, indicating the independent domestication of the two cultivated species in different geographic locations.     

Endothelial S1pr1 regulates pressure overload‐induced cardiac remodelling through AKT‐eNOS pathway

Cardiac vascular microenvironment is crucial for cardiac remodelling during the process of heart failure. Sphingosine 1‐phosphate (S1P) tightly regulates vascular homeostasis via its receptor, S1pr1. We therefore hypothesize that endothelial S1pr1 might be involved in pathological cardiac remodelling. In this study, heart failure was induced by transverse aortic constriction (TAC) operation. S1pr1 expression is significantly increased in microvascular endothelial cells (ECs) of post‐TAC hearts. Endothelial‐specific deletion of S1pr1 significantly aggravated cardiac dysfunction and deteriorated cardiac hypertrophy and fibrosis in myocardium. In vitro experiments demonstrated that S1P/S1pr1 praxis activated AKT/eNOS signalling pathway, leading to more production of nitric oxide (NO), which is an essential cardiac protective factor. Inhibition of AKT/eNOS pathway reversed the inhibitory effect of EC‐S1pr1‐overexpression on angiotensin II (AngII)‐induced cardiomyocyte (CM) hypertrophy, as well as on TGF‐β‐mediated cardiac fibroblast proliferation and transformation towards myofibroblasts. Finally, pharmacological activation of S1pr1 ameliorated TAC‐induced cardiac hypertrophy and fibrosis, leading to an improvement in cardiac function. Together, our results suggest that EC‐S1pr1 might prevent the development of pressure overload‐induced heart failure via AKT/eNOS pathway, and thus pharmacological activation of S1pr1 or EC‐targeting S1pr1‐AKT‐eNOS pathway could provide a future novel therapy to improve cardiac function during heart failure development.     

Observations on the division characterization of diploid nuclear in <Emphasis Type="Italic">Porphyra</Emphasis> (Bangiales,Rhodophyta)

Nuclear divisions of carpospores, conchocelis and conchospores of Porphyra yezoensis, P. haitanensis, P. katadai var. hemiphylla and P. oligospermatangia from China were investigated. The observations showed diploid chromosome numbers of 2n = 6 for P. yezoensis and P. oligospermatangia, and 2n = 10 for P. haitanensis and P. katadai var. hemiphylla. For all four species, somatic pairing of chromosome sets was observed in late prophase. Sister chromosomes separated at anaphase as mitosis took place in carpospores, conchocelis filamentous cells, conchosporangial branch cells and sporangial cells (conchospore formation). Chromosome configurations of tetrad and ring-shaped in conchospore germination were observed, demonstrating the occurrence of meiosis. The characteristics of diploid nuclear division in 2n = 6 species are the same as those of 2n = 10 species. The influence of somatic pairing on nuclear division of diploid cells in Porphyra was discussed.     

Association of Plasma IL-6 and Hsp70 with HRV at Different Levels of PAHs Metabolites

Background

Exposure to polycyclic aromatic hydrocarbons (PAHs) is associated with reduced heart rate variability (HRV), a strong predictor of cardiovascular diseases, but the mechanism is not well understood.

Objectives

We hypothesized that PAHs might induce systemic inflammation and stress response, contributing to altered cardiac autonomic function.

Methods

HRV indices were measured using a 3-channel digital Holter monitor in 800 coke oven workers. Plasma levels of interleukin-6 (IL-6) and heat shock protein 70 (Hsp70) were determined using ELISA. Twelve urinary PAHs metabolites (OH-PAHs) were measured by gas chromatography-mass spectrometry.

Results

We found that significant dose-dependent relationships between four urinary OH-PAHs and IL-6 (all P _trend<0.05); and an increase in quartiles of IL-6 was significantly associated with a decrease in total power (TP) and low frequency (LF) (P _trend = 0.014 and 0.006, respectively). In particular, elevated IL-6 was associated in a dose-dependent manner with decreased TP and LF in the high-PAHs metabolites groups (all P _trend<0.05), but not in the low-PAHs metabolites groups. No significant association between Hsp70 and HRV in total population was found after multivariate adjustment. However, increased Hsp70 was significantly associated with elevated standard deviation of NN intervals (SDNN), TP and LF in the low-PAHs metabolites groups (all P _trend<0.05). We also observed that both IL-6 and Hsp70 significantly interacted with multiple PAHs metabolites in relation to HRV.

Conclusions

In coke oven workers, increased IL-6 was associated with a dose-response decreased HRV in the high-PAHs metabolites groups, whereas increase of Hsp70 can result in significant dose-related increase in HRV in the low-PAHs metabolites groups.     

A hybrid model for erythrocyte membrane: a single unit of protein network coupled with lipid bilayer

To investigate the nanomechanics of the erythrocyte membrane we developed a hybrid model that couples the actin-spectrin network to the lipid bilayer. This model features a Fourier space Brownian dynamics model of the bilayer, a Brownian dynamics model of the actin protofilament, and a modified wormlike-chain model of the spectrin (including a cable-dynamics model to predict the oscillation in tension). This model enables us to predict the nanomechanics of single or multiple units of the protein network, the lipid bilayer, and the effect of their interactions. The present work is focused on the attitude of the actin protofilament at the equilibrium states coupled with the elevations of the lipid bilayer through their primary linkage at the suspension complex in deformations. Two different actin-spectrin junctions are considered at the junctional complex. With a point-attachment junction, large pitch angles and bifurcation of yaw angles are predicted. Thermal fluctuations at bifurcation may lead to mode-switching, which may affect the network and the physiological performance of the membrane. In contrast, with a wrap-around junction, pitch angles remain small, and the occurrence of bifurcation is greatly reduced. These simulations suggest the importance of three-dimensional molecular junctions and the lipid bilayer/protein network coupling on cell membrane mechanics.     

Quantitative response of cell growth and Tuber polysaccharides biosynthesis by medicinal mushroom Chinese truffle Tuber sinense to metal ion in culture medium

During the submerged fermentation of medicinal mushroom Chinese truffle Tuber sinense, there was no significant effect of metal ion on the cell growth and the production of intracellular polysaccharides, while metal ion and its concentration significantly affected the production of extracellular polysaccharides (EPS). By using the approach of "one-variable-at-a-time", 50 mM Mg2+ was identified to be the most favorable for EPS production, and the next was 10 mM K+. A mathematical model, constructed by response surface methodology combination with full factorial design, was applied to study the synergic effect of Mg2+ and K+. EPS production reached its peak value of 5.86 g/L under their optimal combination of 30 mM Mg2+ and 5 mM K+ predicted by the model, which was higher by 130.7% compared with the basal fermentation medium without metal ion. The validation experiment showed the experimental values agreed with the predicted values well. EPS production obtained in this work was the highest reported in the culture of T. sinense.     

Topoisomerase I‐Mediated Antiproliferative Activity of 10‐Substituted and 12‐Substituted Homocamptothecins

Homocamptothecin (hCPT) is an E‐ring modified camptothecin (CPT) analogue, which showed pronounced inhibitory activity of topoisomerase I. In search of novel hCPT‐type anticancer agents, two series of hCPT derivatives were synthesized and evaluated in vitro against three human tumor cell lines. The results indicated that the 10‐substituted hCPT derivatives had a considerably higher cytotoxic activity than the 12‐substituted ones. Among the 10‐substituted compounds, 8a, 8b, 9b , and 9i showed an equivalent or even more potent activity than the positive control drug topotecan against the lung cancer cell line A‐549. Moreover, the hCPT analogues 8a and 8b exhibited a higher topoisomerase I inhibitory activity than CPT at a concentration of 100 μM .