Functional analyses of small secreted cysteine-rich proteins identified candidate effectors in Verticillium dahliae

Secreted small cysteine-rich proteins (SCPs) play a critical role in modulating host immunity in plant–pathogen interactions. Bioinformatic analyses showed that the fungal pathogen Verticillium dahliae encodes more than 100 VdSCPs, but their roles in host–pathogen interactions have not been fully characterized. Transient expression of 123 VdSCP-encoding genes in Nicotiana benthamiana identified three candidate genes involved in host–pathogen interactions. The expression of these three proteins, VdSCP27, VdSCP113, and VdSCP126, in N. benthamiana resulted in cell death accompanied by a reactive oxygen species burst, callose deposition, and induction of defence genes. The three VdSCPs mainly localized to the periphery of the cell. BAK1 and SOBIR1 (associated with receptor-like protein) were required for the immunity triggered by these three VdSCPs in N. benthamiana. Site-directed mutagenesis showed that cysteine residues that form disulphide bonds are essential for the functioning of VdSCP126, but not VdSCP27 and VdSCP113. VdSCP27, VdSCP113, and VdSCP126 individually are not essential for V. dahliae infection of N. benthamiana and Gossypium hirsutum, although there was a significant reduction of virulence on N. benthamiana and G. hirsutum when inoculated with the VdSCP27/VdSCP126 double deletion strain. These results illustrate that the SCPs play a critical role in the V. dahliae–plant interaction via an intrinsic virulence function and suppress immunity following infection.     

Mossy cell synaptic dysfunction causes memory imprecision via miR‐128 inhibition of STIM2 in Alzheimer's disease mouse model

Recently, we have reported that dentate mossy cells (MCs) control memory precision via directly and functionally innervating local somatostatin (SST) inhibitory interneurons. Here, we report a discovery that dysfunction of synaptic transmission between MCs and SST cells causes memory imprecision in a mouse model of early Alzheimer's disease (AD). Single‐cell RNA sequencing reveals that miR‐128 that binds to a 3′UTR of STIM2 and inhibits STIM2 translation is increasingly expressed in MCs from AD mice. Silencing miR‐128 or disrupting miR‐128 binding to STIM2 evokes STIM2 expression, restores synaptic function, and rescues memory imprecision in AD mice. Comparable findings are achieved by directly engineering MCs with the expression of STIM2. This study unveils a key synaptic and molecular mechanism that dictates how memory maintains or losses its details and warrants a promising target for therapeutic intervention of memory decays in the early stage of AD.     

Intrinsically altered lung‐resident γδT cells control lung melanoma by producing interleukin‐17A in the elderly

Cancer is an age‐associated disease, potentially related to the altered immune system of elderly individuals. However, cancer has gradually decreased incidence in the eldest globally such as the most common lung cancer, the mechanisms of which remain to be elucidated. In this study, it was found that the number of lung‐resident γδT cells was significantly increased with altered gene expression in aged mice (20–24 months) versus young mice (10–16 weeks). Aged lung Vγ4⁺ and Vγ6⁺ γδT cells predominantly produced interleukin‐17A (IL‐17A), resulting in increased levels in the serum and lungs. Moreover, the aged mice exhibited smaller tumors and reduced numbers of tumor foci in the lungs after challenge with intravenous injection of B16/F10 melanoma cells compared with the young mice. Aged lung Vγ4⁺ and Vγ6⁺ γδT cells were highly cytotoxic to B16/F10 melanoma cells with higher expression levels of CD103. The markedly longer survival of the challenged aged mice was dependent on γδT17 cells, since neutralization of IL‐17A or depletion of indicated γδT cells significantly shortened the survival time. Consistently, supplementation of IL‐17A significantly enhanced the survival time of young mice with lung melanoma. Furthermore, the anti‐tumor activity of aged lung γδT17 cells was not affected by alterations in the load and composition of commensal microbiota, as demonstrated through co‐housing of the aged and young mice. Intrinsically altered lung γδT17 cells underlying age‐dependent changes control lung melanoma, which will help to better understand the lung cancer progression in the elderly and the potential use of γδT17 cells in anti‐tumor immunotherapy.     

Genetically Encoded FRET Biosensor Detects the Enzymatic Activity of Prostate-Specific Antigen

Prostate cancer is the most common cancer among men beyond 50 years old, and ranked the second in mortality. The level of Prostate-specific antigen (PSA) in serum has been a routine biomarker for clinical assessment of the cancer development, which is detected mostly by antibody-based immunoassays. The proteolytic activity of PSA also has important functions. Here a genetically encoded biosensor based on fluorescence resonance energy transfer (FRET) technology was developed to measure PSA activity. In vitro assay showed that the biosensor containing a substrate peptide ‘RLSSYYSGAG’ had 400% FRET change in response to 1 µg/ml PSA within 90 min, and could detect PSA activity at 25 ng/ml. PSA didn’t show enzymatic activity toward the biosensor in serum solution, likely reflecting the existence of other inhibitory factors besides Zn2+. By expressing the biosensor on cell plasma membrane, the FRET responses were significant, but couldn’t distinguish well the cultured prostate cancer cells from non-prostate cancer cells under microscopy imaging, indicating insufficient speci- ficity to PSA. The biosensor with the previously known ‘HSSKLQ’ substrate showed little response to PSA in solution. In summary, we developed a genetically encoded FRET biosensor to detect PSA activity, which may serve as a useful tool for relevant applications, such as screening PSA activation substrates or inhibitors; the purified biosensor protein can also be an alternative choice for measuring PSA activity besides currently commercialized Mu-HSSKLQ-AMC substrate from chemical synthesis.     

Perfect Narrowband Absorber Based on Patterned Graphene-Silica Multilayer Hyperbolic Metamaterials

Plasmonics - Graphene-based hyperbolic metamaterials are well known for their optical anisotropy, high absorption of electromagnetic radiation, and low energy loss. We proposed a novel multilayer...     

GABA consumption during early pregnancy impairs endometrial receptivity and embryo development in mice

γ‐Aminobutyrate (GABA) is commonly used as a food supplement and a health care product by young females, due to its positive roles in relieving stress, alleviating anxiety, and improving sleep. However, its recommended daily dose in different products varies widely. Besides, it is unknown whether, and how, GABA consumption during early pregnancy influences pregnancy establishment. In this study, we found that when pregnant mice were treated with a high (12.5 mg/g) dose of GABA (orally) during preimplantation, there was a reduction in the number of implantation sites on day 5 of pregnancy. Also, among these unimplanted embryos, most exhibited morphological degeneration and developmental retardation, and only a few of them developed into blastocysts but could not implant into the uterus. Moreover, the expression of uterine receptivity–related factors—LIF, E‐cadherin, and HOXA10—were all downregulated, while the number of uterine glands was reduced in the high GABA dose group. Finally, in vitro results demonstrated that GABA (ranging from 10 to 50 μg/μL) markedly inhibited preimplantation embryo development in a dose‐response manner. However, this inhibitory effect was not observed when the embryos were pretreated with 40 μΜ 2‐hydroxysaclofen, a GABA_B antagonist, indicating that GABA exerts its inhibitory effects via its B‐type receptor. Our results suggest that exposure to certain GABA concentrations, during early pregnancy, can impair preimplantation embryo development via its B‐type receptor, and endometrial receptivity, which greatly disturbs early embryo implantation in mice. These findings could raise concerns about GABA consumption during the early stages of pregnancy.     

Diverse Roles of the Salicylic Acid Receptors NPR1 and NPR3/NPR4 in Plant Immunity

The plant defense hormone salicylic acid (SA) is perceived by two classes of receptors, NPR1 and NPR3/NPR4. They function in two parallel pathways to regulate SA-induced defense gene expression. To better understand the roles of the SA receptors in plant defense, we systematically analyzed their contributions to different aspects of Arabidopsis (Arabidopsis thaliana) plant immunity using the SA-insensitive npr1-1 npr4-4D double mutant. We found that perception of SA by NPR1 and NPR4 is required for activation of N-hydroxypipecolic acid biosynthesis, which is essential for inducing systemic acquired resistance. In addition, both pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) are severely compromised in the npr1-1 npr4-4D double mutant. Interestingly, the PTI and ETI attenuation in npr1-1 npr4-4D is more dramatic compared with the SA-induction deficient2-1 (sid2-1) mutant, suggesting that the perception of residual levels of SA in sid2-1 also contributes to immunity. Furthermore, NPR1 and NPR4 are involved in positive feedback amplification of SA biosynthesis and regulation of SA homeostasis through modifications including 5-hydroxylation and glycosylation. Thus, the SA receptors NPR1 and NPR4 play broad roles in plant immunity.     

基于CRISPR/Cas9的基因分析方法研究进展

自2012年首次证明了CRISPR/Cas9可以在体外进行DNA切割试验以来,CRISPR技术逐渐在基因编辑研究中获得了迅速的发展,除了应用于基因编辑领域之外,它在基因表达调控、基因成像、基因分析等方面也展现出了巨大的应用潜力。尤其在基因分析领域,CRISPR技术由于其精确的基因识别、室温的反应条件、易设计性和操作性等特色,使得一系列新型的基因检测技术得以发展,并取得了超越常规技术的一些检测参数。本文以Cas9蛋白为对象,综述了近些年来在该领域取得的研究进展。主要论述Cas9蛋白的功能、改造、引导RNA(sgRNA)的设计及其在基因分析方法上的应用。