Biophysical and Structural Characterization of Novel RAS-Binding Domains (RBDs) of PI3Kα and PI3Kγ

Phosphatidylinositol-3-kinases (PI3Ks) are lipid kinases that phosphorylate phosphatidylinositol 4,5-bisphosphate to generate a key lipid second messenger, phosphatidylinositol 3,4,5-bisphosphate. PI3Kα and PI3Kγ require activation by RAS proteins to stimulate signaling pathways that control cellular growth, differentiation, motility and survival. Intriguingly, RAS binding to PI3K isoforms likely differ, as RAS mutations have been identified that discriminate between PI3Kα and PI3Kγ, consistent with low sequence homology (23%) between their RAS binding domains (RBDs). As disruption of the RAS/PI3Kα interaction reduces tumor growth in mice with RAS- and epidermal growth factor receptor driven skin and lung cancers, compounds that interfere with this key interaction may prove useful as anti-cancer agents. However, a structure of PI3Kα bound to RAS is lacking, limiting drug discovery efforts. Expression of full-length PI3K isoforms in insect cells has resulted in low yield and variable activity, limiting biophysical and structural studies of RAS/PI3K interactions. This led us to generate the first RBDs from PI3Kα and PI3Kγ that can be expressed at high yield in bacteria and bind to RAS with similar affinity to full-length PI3K. We also solved a 2.31 Å X-ray crystal structure of the PI3Kα-RBD, which aligns well to full-length PI3Kα. Structural differences between the PI3Kα and PI3Kγ RBDs are consistent with differences in thermal stability and may underly differential RAS recognition and RAS-mediated PI3K activation. These high expression, functional PI3K RBDs will aid in interrogating RAS interactions and could aid in identifying inhibitors of this key interaction.     

Ptk2b deletion improves mice folliculogenesis and fecundity via inhibiting follicle loss mediated by Erk pathway

Ptk2b has been found playing critical roles in oocyte maturation and subsequent fertilization in vitro. But what is the exact in vivo function in reproduction still elusive. Here, by constructing Ptk2b mutant mice, we found Ptk2b was not essential for mice fertility, unexpectedly, contrary to previously reported in vitro findings, we found Ptk2b ablation significantly improved female fecundity. Follicle counting indicated that the number of primordial follicles and growing follicles in matured mice was significantly increased in the absence of Ptk2b, whereas the primordial follicle formation showed no defects. We also found this regulation was in an autophosphorylation independent pathway, as autophosphorylation site mutant mice (PTK2B^Y402F) show no phenotype in female fertility. Further biochemistry studies revealed that Ptk2b ablation promotes folliculogenesis via Erk pathway mediate follicle survival. Together, we found a novel biological function of Ptk2b in folliculogenesis, which could be potentially used as a therapeutic target for corresponding infertility.     

Long noncoding RNA HNF1A‐AS1 regulates proliferation and apoptosis of glioma through activation of the JNK signaling pathway via miR‐363‐3p/MAP2K4

Long noncoding RNAs (lncRNAs) have been proven to exert important functions in the various biological processes of human cancers. It has been reported that lncRNA HNF1 homeobox A antisense RNA 1 (HNF1A‐AS1) was abnormally expressed and played a role in the initiation and development of various human cancers. In this study, we confirmed that the expression level of HNF1A‐AS1 was increased in glioma tissues and cells. Knockdown of HNF1A‐AS1 inhibited cell proliferation and promoted cell apoptosis in glioma. Then, we disclosed the downregulation of miR‐363‐3p in glioma tissues and cell lines. The interaction between HNF1A‐AS1 and miR‐363‐3p was identified in glioma cells. Furthermore, an inverse correlation between HNF1A‐AS1 and miR‐363‐3p was observed in glioma tissues. Afterwards, we recognized that MAP2K4 was a direct target of miR‐363‐3p. The expression of MAP2K4 was negatively correlated with miR‐363‐3p while positively related to HNF1A‐AS1 in glioma tissues. We also found the regulatory effect of HNF1A‐AS1 on the MAP2K4‐dependent JNK signaling pathway. All findings indicated that HNF1A‐AS1 induces the upregulation of MAP2K4 to activate the JNK signaling pathway to promote glioma cell growth by acting as a miR‐363‐3p sponge.     

2-羟基-3-甲基蒽醌抑制结直肠癌的作用及机制研究

为观察2-羟基-3-甲基蒽醌(HMA)对结直肠癌细胞增殖的影响并探讨其作用机制,本研究采用CCK8法检测HMA对结直肠癌细胞增殖的影响;Heochst-33343/PI染色检测细胞凋亡情况;同时检测细胞内ROS及GSH含量变化并应用Western blot检测细胞凋亡相关蛋白及Keap-1/Nrf-2/ARE信号途径相关蛋白的表达。实验结果显示,HMA给予结直肠癌细胞后,细胞内ROS含量升高,GSH含量减少;HMA通过抑制Keap-1/Nrf-2/HO-1通路,诱导细胞发生凋亡。综上表明HMA具有抑制结肠癌细胞增殖的作用,其机制可能与破坏细胞内氧化还原平衡,抑制Keap-1/Nrf-2/HO-1通路有关。     

A novel role of Hippo-Yap/TAZ signaling pathway in lymphatic vascular development

The lymphatic vasculature plays important role in regulating fluid homeostasis, intestinal lipid absorption, and immune surveillance in humans. Malfunction of lymphatic vasculature leads to several human diseases. Understanding the fundamental mechanism in lymphatic vascular development not only expand our knowledge, but also provide a new therapeutic insight. Recently, Hippo-YAP/TAZ signaling pathway, a key mechanism of organ size and tissue homeostasis, has emerged as a critical player that regulate lymphatic specification, sprouting, and maturation. In this review, we discuss the mechanistic regulation and pathophysiological significant of Hippo pathway in lymphatic vascular development.     

基于对JNK信号通路的调控探讨齐墩果酸对食管癌细胞凋亡的影响

摘要 目的：本研究通过对JNK信号通路的调控来探讨齐墩果酸( oleanolic acid,OA) 对食管癌细胞凋亡的影响。方法：对食管癌细胞EC109进行培养,以MTT法分析不同浓度齐墩果酸对食管癌细胞EC109的生长抑制作用,采用流式细胞术考察齐墩果酸对EC109细胞凋亡的影响,以Western blot实验检测JNK通路蛋白的表达情况。结果：不同浓度齐墩果酸作用Eca109细胞48 h后,均有显著的抑制作用（P<0.05）,且随着齐墩果酸浓度的增加,对Eca109的抑制作用逐渐增强。与对照组相比,各浓度OA组的Eca109细胞的凋亡率分别为8.03±0.34 %,12.82±0.28 %,19.34±0.79 %和32.21±0.81 %,均显著增加（P<0.05）,且随着OA浓度的增加,细胞凋亡率显著升高。与对照组相比,不同浓度OA组的P-JNK、Bak、Bax表达量均显著升高（P<0.05）,Bcl-2表达量显著降低（P<0.05）,JNK表达量无显著差异（P>0.05）,对OA组(1.2 mmol/L)相比,OA组(2.4 mmol/L) Bak、Bax表达量均显著升高（P<0.05）,Bcl-2表达量显著降低（P<0.05）,P-JNK、JNK表达量无显著差异（P>0.05）。结论：齐墩果酸能通过对JNK信号通路的调控促进食管癌细胞的凋亡,且随着浓度的增强,细胞凋亡率显著升高。     

植物CBL-CIPK信号系统响应非生物胁迫的调控机制

钙调磷酸酶B蛋白(CBLs)及其互作蛋白激酶(CIPKs)组成的信号系统是非生物逆境响应的重要调控网络。CBL-CIPK系统通过磷酸化感应并解码Ca²⁺信号, 参与植物对非生物胁迫的应答调控。该文综述了CBLs和CIPKs结构、CBLs-CIPKs对不同底物磷酸化及其响应非生物胁迫调控机制的研究进展, 并展望了未来的研究方向, 以期为作物抗逆性遗传改良提供思路。     

Potassium and phosphorus transport and signaling in plants

Nitrogen(N), potassium(K), and phosphorus(P) are essential macronutrients for plant growth and development, and their availability affects crop yield. Compared with N, the relatively low availability of K and P in soils limits crop production and thus threatens food security and agricultural sustainability. Improvement of plant nutrient utilization efficiency provides a potential route to overcome the effects of K and P deficiencies. Investigation of the molecular mechanisms underlying how plants sense, absorb, transport, and use K and P is an important prerequisite to improve crop nutrient utilization efficiency. In this review, we summarize current understanding of K and P transport and signaling in plants, mainly taking Arabidopsis thaliana and rice(Oryza sativa) as examples. We also discuss the mechanisms coordinating transport of N and K, as well as P and N.     

鳞翅目昆虫抗病毒免疫反应的研究进展

鳞翅目昆虫种类繁多,对农业生产和人类生活产生重大影响,宿主昆虫与病毒相互关系的研究对于利用病毒杀虫剂进行害虫治理和益虫病毒性疾病的预防具有重要意义.因此,鳞翅目昆虫与病毒的互作研究显得尤为重要,宿主昆虫的免疫系统在抗病毒感染过程中发挥着关键作用,对病毒产生不同程度的免疫反应.本文综述了昆虫围食膜和中肠对病毒入侵的防御作用,病毒进入体腔后昆虫所产生的细胞免疫和体液免疫反应,以及RNAi、细胞的自噬与凋亡、Toll、Imd、JAK-STAT和STING信号通路等相关的抗病毒免疫途径,并对昆虫抗病毒免疫研究的制约因素和未来鳞翅目昆虫抗病毒免疫的研究重点进行了讨论,以期为害虫的生物防治和益虫疾病的防控提供理论依据.