Genome-wide CRISPR screen identifies synthetic lethality between DOCK1 inhibition and metformin in liver cancer

Metformin is currently a strong candidate anti-tumor agent in multiple cancers. However, its anti-tumor effectiveness varies among different cancers or subpopulations, potentially due to tumor heterogeneity. It thus remains unclear which hepatocellular carcinoma (HCC) patient subpopulation(s) can benefit from metformin treatment. Here, through a genome-wide CRISPR-Cas9-based knockout screen, we find that DOCK1 levels determine the anti-tumor effects of metformin and that DOCK1 is a synthetic lethal target of metformin in HCC. Mechanistically, metformin promotes DOCK1 phosphorylation, which activates RAC1 to facilitate cell survival, leading to metformin resistance. The DOCK1-selective inhibitor, TBOPP, potentiates anti-tumor activity by metformin in vitro in liver cancer cell lines and patient-derived HCC organoids, and in vivo in xenografted liver cancer cells and immunocompetent mouse liver cancer models. Notably, metformin improves overall survival of HCC patients with low DOCK1 levels but not among patients with high DOCK1 expression. This study shows that metformin effectiveness depends on DOCK1 levels and that combining metformin with DOCK1 inhibition may provide a promising personalized therapeutic strategy for metformin-resistant HCC patients.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13238-022-00906-6.     

Understanding pathogen–host interplay by expression profiles of lncRNA and mRNA in the liver of Echinococcus multilocularis-infected mice

Almost all Echinococcus multilocularis (Em) infections occur in the liver of the intermediate host, causing a lethal zoonotic helminthic disease, alveolar echinococcosis (AE). However, the long non-coding RNAs (lncRNAs) expression profiles of the host and the potential regulatory function of lncRNA during Em infection are poorly understood. In this study, the profiles of lncRNAs and mRNAs in the liver of mice at different time points after Em infection were explored by microarray. Thirty-one differentially expressed mRNAs (DEMs) and 68 differentially expressed lncRNAs (DELs) were found continuously dysregulated. These DEMs were notably enriched in “antigen processing and presentation”, “Th1 and Th2 cell differentiation” and “Th17 cell differentiation” pathways. The potential predicted function of DELs revealed that most DELs might influence Th17 cell differentiation and TGF-β/Smad pathway of host by trans-regulating SMAD3, STAT1, and early growth response (EGR) genes. At 30 days post-infection (dpi), up-regulated DEMs were enriched in Toll-like and RIG-I-like receptor signaling pathways, which were validated by qRT-PCR, Western blotting and downstream cytokines detection. Furthermore, flow cytometric analysis and serum levels of the corresponding cytokines confirmed the changes in cell-mediated immunity in host during Em infection that showed Th1 and Th17-type CD4⁺ T-cells were predominant at the early infection stage whereas Th2-type CD4⁺ T-cells were significantly higher at the middle/late stage. Collectively, our study revealed the potential regulatory functions of lncRNAs in modulating host Th cell subsets and provide novel clues in understanding the influence of Em infection on host innate and adaptive immune response.     

A bacterial effector counteracts host autophagy by promoting degradation of an autophagy component

Beyond its role in cellular homeostasis, autophagy plays anti‐ and promicrobial roles in host–microbe interactions, both in animals and plants. One prominent role of antimicrobial autophagy is to degrade intracellular pathogens or microbial molecules, in a process termed xenophagy. Consequently, microbes evolved mechanisms to hijack or modulate autophagy to escape elimination. Although well‐described in animals, the extent to which xenophagy contributes to plant–bacteria interactions remains unknown. Here, we provide evidence that Xanthomonas campestris pv. vesicatoria (Xcv) suppresses host autophagy by utilizing type‐III effector XopL. XopL interacts with and degrades the autophagy component SH3P2 via its E3 ligase activity to promote infection. Intriguingly, XopL is targeted for degradation by defense‐related selective autophagy mediated by NBR1/Joka2, revealing a complex antagonistic interplay between XopL and the host autophagy machinery. Our results implicate plant antimicrobial autophagy in the depletion of a bacterial virulence factor and unravel an unprecedented pathogen strategy to counteract defense‐related autophagy in plant–bacteria interactions.     

草鱼血液学的研究 Ⅰ.九项血液常数的周年变化

用741尾健康草鱼种作红细胞、血红蛋白、红细胞比积、红细胞平均体积、红细胞平均血红蛋白量、红细胞平均血红蛋白浓度、红细胞沉降率、血浆总蛋白和血浆葡萄糖浓度等九项血液常数的测定。所得的年均值经变异系数分析,除红细胞沉降率和血浆葡萄糖浓度外,其余各项常数的可靠性基本一致。另从周年变动的规律分析,高值出现在冬夏季,低值出现的月份较为分散。水温仅对总蛋白含量的变动呈现显著的负相关(P<0.01)。而体重与血液常数存在着一定的相关因素,在10—90克之间的鱼种中,血红蛋白、红细胞比积、红细胞平均体积、红细胞平均血红蛋白量与体重呈现直线正相关;红细胞沉降率为负相关。     

Oxygen binding and oxidation reactions of human hemoglobin conjugated to carboxylate dextran

Human hemoglobin (Hb) conjugated to benzene tetracarboxylate substituted dextran produces a polymeric Hb (Dex-BTC-Hb) with similar oxygen affinity to that of red blood cells (P(50)=28-29 mm Hg). Under physiological conditions, the oxygen affinity (P(50)) of Dex-BTC-Hb is 26 mm Hg, while that of native purified human HbA(0) is 14 mm Hg, but it exhibits a slight reduction in cooperativity (n(50)), Bohr effect, and lacks sensitivity to inositol hexaphosphate (IHP), when compared to HbA(0). Oxygen-binding kinetics, measured by rapid mixing stopped-flow method showed comparable oxygen dissociation and association rates for both HbA(0) and Dex-BTC-Hb. The rate constant for NO-mediated oxidation of the oxy form of Dex-BTC-Hb, which is governed by NO entry to the heme pocket, was reduced to half of the value obtained for HbA(0). Moreover, Dex-BTC-Hb is only slightly more sensitive to oxidative reactions than HbA(0), as shown by about 2-fold increase in autoxidation, and slightly higher H(2)O(2) reaction and heme degradation rates. Dextran-BTC-based modification of Hb produced an oxygen-carrying compound with increased oxygen release rates, decreased oxygen affinity and reduced nitric oxide scavenging, desirable properties for a viable blood substitute. However, the reduction in the allosteric function of this protein and the lack of apparent quaternary T-->R transition may hinder its physiological role as an oxygen transporter.     

中国水仙(Narcissus tazetta var.chinensis)的组织培养

以栽培的中国水仙Narcissus tazetta var.Chinensis鳞茎为实验材料,采取“无液处理”的简捷方法获取外植体,并筛选出中国水仙离体鳞茎培养的最佳培养基。     

伊贝母组织培养中次生代谢产物的研究

以组织培养和细胞液印迹直接荧光观察法相结合,建立了伊贝母组织培养生物合成高含量贝母碱的技术,并通过薄层层析和薄层扫描对贝母生物碱的组成进行了比较分析。结果表明,不论是组织培养物还是栽培贝母中都含有母碱的主要成分－西贝素。但根中贝母碱的成分要比其它组织或器官中更为复杂,含量和活性也较高。继代培养８代的不定芽和不定根中贝母碱的含量分别高于栽培５年贝母根的０．０１％和０．０２％。