Effects of TYROBP Deficiency on Neuroinflammation of a Alzheimer’s Disease Mouse Model Carrying a PSEN1 p.G378E Mutation

Objective To study the effects of TYRO protein kinase-binding protein(TYROBP)deficiency on learning behavior,glia activation and pro-inflammatory cycokines,and Tau phosphorylation of a new Alzheimer’s disease(AD)mouse model carrying a PSEN1 p.G378E mutation.Methods A new AD mouse model carrying PSEN1 p.G378E mutation was built based on our previously found AD family which might be ascribed to the PSEN1 mutation,and then crossed with TYROBP deficient mice to produce the heterozygous hybrid mice(PSEN1^(G378E)/WT;Tyrobp^(+/-))and the homozygous hybrid mice(PSEN1^(G378E/G378E);Tyrobp^(-/-)).Water maze test was used to detect spatial learning and memory ability of mice.After the mice were sacrificed,the hippocampus was excised for further analysis.Immunofluorescence was used to identify the cell that expresses TYROBP and the number of microglia and astrocyte.Western blot was used to detect the expression levels of Tau and phosphorylated Tau(p-Tau),and ELISA to measure the levels of pro-inflammatory cytokines.Results Our results showed that TYROBP specifically expressed in the microglia of mouse hippocampus.Absence of TYROBP in PSEN1^(G378E) mutation mouse model prevented the deterioration of learning behavior,decreased the numbers of microglia and astrocytes,and the levels of interleukin-6,interleukin-1βand tumor necrosis factor-αin the hippocampus(all P<0.05).The ratios of AT8/Tau5,PHF1/Tau5,pT181/Tau5,pT231/Tau5 and p-ERK/ERK were all higher in homozygous hybrid mice(PSEN1^(G378E/G378E);Tyrobp^(-/-) mice)compared with PSEN1^(G378E/G378E) mice(all P<0.05).Conclusions TYROBP deficiency might play a protective role in the modulation of neuroinflammation of AD.However,the relationship between neuroinflammation processes involving microglia and astrocyte activation,and release of pro-inflammatory cytokines,and p-Tau pathology needs further study.

PRPS2 mutations drive acute lymphoblastic leukemia relapse through influencing PRPS1/2 hexamer stability

Tumor relapse is the major cause of treatment failure in childhood acute lymphoblastic leukemia(ALL),yet the underlying mechanisms are still elusive.Here,we demonstrate that phosphoribosyl pyrophosphate synthetase 2(PRPS2)mutations drive ALL relapse through influencing PRPS1/2 hexamer stability.Ultra-deep sequencing was performed to identify PRPS2 mutations in ALL samples.The effects of PRPS2 mutations on cell survival,cell apoptosis,and drug resistance were evaluated.In vitro PRPS2 enzyme activity and ADP/GDP feedback inhibition of PRPS enzyme activity were assessed.Purine metabolites were analyzed by ultra-performance liquid-chromatography tandem mass spectrometry(UPLC–MS/MS).Integrating sequencing data with clinical information,we identified PRPS2 mutations only in relapsed childhood ALL with thiopurine therapy.Functional PRPS2 mutations mediated purine metabolism specifically on thiopurine treatment by influencing PRPS1/2 hexamer stability,leading to reduced nucleotide feedback inhibition of PRPS activity and enhanced thiopurine resistance.The 3-amino acid V103-G104-E105,the key difference between PRPS1 and PRPS2,insertion in PRPS2 caused severe steric clash to the interface of PRPS hexamer,leading to its low enzyme activity.In addition,we demonstrated that PRPS2 P173R increased thiopurine resistance in xenograft models.Our work describes a novel mechanism by which PRPS2 mutants drive childhood ALL relapse and highlights PRPS2 mutations as biomarkers for relapsed childhood ALL.

PUMA facilitates EMI 1-promoted cytoplasmic Rad51 ubiquitination and inhibits DNA repair in stem and progenitor cells

Maintenance of genetic stability via proper DNA repair in stem and progenitor cells is essential for the tissue repair and regeneration,while preventing cell transformation after damage.Loss of PUMA dramatically increases the survival of mice after exposure to a lethal dose of ionizing radiation(IR),while without promoting tumorigenesis in the long-term survivors.This finding suggests that PUMA(p53 upregulated modulator of apoptosis)may have a function other than regulates apoptosis.Here,we identify a novel role of PUMA in regulation of DNA repair in embryonic or induced pluripotent stem cells(PSCs)and immortalized hematopoietic progenitor cells(HPCs)after IR.We found that PUMA-deficient PSCs and HPCs exhibited a significant higher doublestrand break(DSB)DNA repair activity via Rad51-mediated homologous recombination(HR).This is because PUMA can be associated with early mitotic Inhibitor 1(EMI1)and Rad51 in the cytoplasm to facilitate EMI1-mediated cytoplasmic Rad51 ubiquitination and degradation,thereby inhibiting Rad51 nuclear translocation and HR DNA repair.Our data demonstrate that PUMA acts as a repressor for DSB DNA repair and thus offers a new rationale for therapeutic targeting of PUMA in regenerative cells in the context of DNA damage.

Hi-TOM: a platform for high-throughput tracking of mutations induced by CRISPR/Cas systems

The CRISPR/Cas system has been extensively applied to make precise genetic modifications in various organisms. Despite its importance and widespread use, large-scale mutation screening remains time-consuming, labour-intensive and costly. Here, we developed Hi-TOM(available at http://www.hi-tom.net/hi-tom/), an online tool to track the mutations with precise percentage for multiple samples and multiple target sites. We also described a corresponding next-generation sequencing(NGS) library construction strategy by fixing the bridge sequences and barcoding primers. Analysis of the samples from rice, hexaploid wheat and human cells reveals that the Hi-TOM tool has high reliability and sensitivity in tracking various mutations, especially complex chimeric mutations frequently induced by genome editing. Hi-TOM does not require special design of barcode primers,cumbersome parameter configuration or additional data analysis. Thus, the streamlined NGS library construction and comprehensive result output make Hi-TOM particularly suitable for high-throughput identification of all types of mutations induced by CRISPR/Cas systems.

Upgrading of derived pyrolysis vapors for the production of biofuels from corncobs

A bubbling fluidized bed pyrolyzer was integrated with an in-situ honeycomb as a catalytic upgrading zone for the conversion of biomass to liquid fuels. In the upgrading zone, zeolite coated ceramic honeycomb （ZCCH） catalysts consisting of ZSM-5 （Si/ Al = 25） were stacked and N2 or recycled non-condensable gas was used as a carrier gas. Ground corncob particles were fast pyrolyzed in the bubbling bed using fine sand particles as a heat carrier and the resulting pyrolysis vapors were passed on-line over the catalytic upgrading zone. The influence of carrier gas, temperature, and weight hourly space velocity （WHSV） of catalyst on the oil product properties, distribution and mass balance were studied. Using ZCCH effectively increased the hydrocarbon yield and the heating value of the dry oil, especially in the presence of the recycled noncondensable gas. Even a low usage of zeolite catalyst at WSHV of 180 h^-1 was effective in upgrading the pyrolysis oil and other light olefins. The highest hydrocarbon （≥C2） and liquid aromatics yields reached to 14.23 and 4.17 wt-%, respectively. The undesirable products including light oxygenates, furans dramatically decreased in the presence of the ZCCH catalyst.

High discharged energy density of polymer nanocomposites induced by Nd-doped BaTiO_(3)nanoparticles

A flexible polymer nanocomposite has been developed via introducing Nd-doped BaTiO_(3)nanoparticles into the poly(vinylidene fluoride).This nanocomposite delivers a discharged energy density up to 12.5 J/cm^(3)under an electric field of 420 kV/mmwith only a small loading of 1 vol.%Nd-BaTiO_(3).High discharged energy density,mechanical flexibility,light weight,ease fabrication and low cost makes it attractive for advanced microelectronics and electrical power systems.Our results demonstrate that ceramics with giant dielectric permittivity as viable fillers for polymer nanocomposite dielectrics with higher energy density.

Improved thermal conductivity and breakdown strength of PVDF-based composites by improving the dispersion of BN

In order to adapt to the development of electronic devices,it is necessary to improve the thermal conductivity and breakdown strength of composites.Boron nitride(BN)is an ideal candidate material with high breakdown strength and thermal conductivity.There-fore,the introduction of BN nanosheets into the polyvinylidene fluoride(PVDF)matrix can improve the thermal conductivity and breakdown strength of the composites at the same time.However,BN nanosheets can easily agglomerate in the matrix,which limits the improvement of the properties of the composites.To overcome this difficulty,appropriate water-bath heating was used to improve the fluidity of PVDF.Therefore,the dispersion of the filler is improved.When the volume fraction of BN nanosheets is 3%and the preparation temperature is 45℃,the energy storage density of the compos-ites reached 18.5 J/cm^(3) at 540 kV/mm.At this point,the thermal conductivity was 0.49 W/(m⋅K),3.5 times that of the pure PVDF film.