Targeting cullin-RING ligases for cancer treatment: rationales,advances and therapeutic implications

New therapeutic intervention strategies for the treatment of human malignancies are always desired. Approval of bortezomib as a front-line treatment for multiple myeloma highlighted the significance of ubiquitin–proteasome system (UPS) as a promising therapeutic target. However, due to the broad impact of proteasome inhibition, deleterious side effects have been reported with bortezomib treatment. Cullin RING ligases (CRLs)-mediated ubiquitin conjugation process is responsible for the ubiquitin conjugation of 20 % cellular proteins that are designated for degradation through the UPS, most of them are critical proteins involved in cell cycle progression, signaling transduction and apoptosis. Studies have depicted the upstream NEDDylation pathway that controls the CRL activity by regulating the conjugation of an ubiquitin-like-protein NEDD8 to the cullin protein in the complex. A specific pharmaceutical inhibitor of NEDD8 activating enzyme (NAE; E1) MLN4924 was recently developed and has been promoted to Phase I clinical trials for the treatment of several human malignancies. This article summarizes the most recent understanding about the process of NEDD8 conjugation, its relevance for cancer therapy and molecular mechanisms responsible for the potent anti-tumor activity of MLN4924.     

Life history,diagnosis, and biological aspects of Engytatus varians (Hemiptera: Miridae), a predator of Bactericera cockerelli (Hemiptera: Triozidae)

The life cycle and several life parameters of the zoophytophagous predator Engytatus varians (Distant) (Heteroptera: Miridae), including nymphal growth according to Dyar’s rule, were examined in the laboratory. The egg, nymph (five instars), and adult stages were 9.20, 17.36, and 19.02?d in length, respectively. The growth ratio for nymphs was consistent with Dyar’s rule based on the lengths of the femora of the forelegs, the tibiae and femora of the middle legs, and the antennae. Some biological characteristics of E. varians were also evaluated when the mirid was fed three different diets (B. cockerelli third instars, Sitotroga cerealella Olivier [Lepidoptera: Gelechiidae] eggs, and a mixture of both instars and eggs). The length of the nymphal stage was three days longer on a diet of only S. cerealella eggs than when the mirids were fed the third instars of B. cockerelli only or a mixture of both. The sex ratio was not affected by the type of diet. Nymphs of E. varians consumed B. cockerelli nymphs (80–85) when fed third instars only and third instars?+?S. cerealella eggs, respectively. The potential use of this predator as a biological control agent of B. cockerelli is discussed.     

基于VPM模型的长白山自然保护区植被总初级生产力动态变化

总初级生产力(GPP)是碳循环的重要参数,它的准确估算对碳循环及全球气候变化研究有重要作用.利用VPM模型及2000—2015年MOD09A1数据/气候因子的空间数据,对长白山自然保护区的植被GPP进行模拟.结果表明: 2000—2015年,保护区GPP年均值为1203 g C·m^-2·a^-1,GPP呈极显著趋势增长.森林植被GPP年际增长变化在不同植被垂直带下没有显著区别,但从高山苔原带往上,GPP年际增长明显减小.GPP与降水的年际相关性不显著,与温度的正相关关系集中分布在阔叶红松林带和高山苔原带.春季气温对GPP影响最大,有80%像元显示与气温呈正相关.GPP与温度的年际相关性明显高于降水.     

Pyrroloquinoline quinone inhibits oxygen/glucose deprivation-induced apoptosis by activating the PI3K/AKT pathway in cardiomyocytes

The purposes of this study were to examine the protective effect of pyrroloquinoline quinone (PQQ) on oxygen/glucose deprivation (OGD)-induced injury to H9C2 rat cardiomyocytes and to investigate the mechanism. Using H9C2 cells cultured in vitro, we examined changes in cell viability with an MTT assay at 12, 24, and 48 h after injury induced by OGD. Various concentrations of PQQ (1, 10, and 100 μM) were added, and the effect of PQQ on cell viability after OGD was assessed using the MTT assay. Thus, the optimal concentration of PQQ for the protection of cardiomyocytes against oxygen and glucose deprivation injury was determined. We also used flow cytometry analysis to examine the effect of PQQ on H9C2 cells with OGD-induced injury. The molecular probe 2′,7′-dichlorofluorescin diacetate was used to label the H9C2 cells, and flow cytometry was used to detect the effect of PQQ on reactive oxygen species (ROS) content. After labeling the H9C2 cells using a mitochondrial green fluorescent probe (Mito-Tracker Green), we measured the change in the mitochondrial content of PQQ-treated H9C2 cells. Western blotting was used to examine the effect of PQQ on the phosphatidylinositol 3-kinase (PI3K)/Akt pathway in the H9C2 cells. The results of the MTT assay showed that 48 h of OGD significantly injured the H9C2 cells (p < 0.01) and that treatment with 100 μM PQQ effectively decreased the level of OGD-induced injury (p < 0.01). The results of the flow cytometry analysis showed that PQQ significantly reduced apoptosis in H9C2 cells subjected to OGD (p < 0.05). In addition, OGD significantly increased the ROS level in H9C2 cells (p < 0.01), and PQQ significantly inhibited this increase (p < 0.05). The results of the Mito-Tracker Green staining suggested that PQQ effectively inhibited the decrease in mitochondrial content caused by OGD (p < 0.05). Western blot analysis showed that PQQ partially reversed the decrease in Akt phosphorylation that was caused by OGD (p < 0.05). PQQ treatment dose-dependently protects H9C2 cells from OGD-induced injury by reducing apoptosis, decreasing intracellular ROS levels, and rescuing the OGD-induced decrease in mitochondrial content. The protective effect of PQQ may be related to its effects on the PI3K/Akt pathway.     

Allografts of the acellular sciatic nerve and brain-derived neurotrophic factor repair spinal cord injury in adult rats

Objective

We aimed to investigate whether an innovative growth factor-laden scaffold composed of acellular sciatic nerve (ASN) and brain-derived neurotrophic factor (BDNF) could promote axonal regeneration and functional recovery after spinal cord injury (SCI).

Methods

Following complete transection at the thoracic level (T9), we immediately transplanted the grafts between the stumps of the severed spinal cords. We evaluated the functional recovery of the hindlimbs of the operated rats using the BBB locomotor rating scale system every week. Eight weeks after surgery, axonal regeneration was examined using the fluorogold (FG) retrograde tracing method. Electrophysiological analysis was carried out to evaluate the improvement in the neuronal circuits. Immunohistochemistry was employed to identify local injuries and recovery.

Results

The results of the Basso-Beattie-Bresnahan (BBB) scale indicated that there was no significant difference between the individual groups. The FG retrograde tracing and electrophysiological analyses indicated that the transplantation of ASN-BDNF provided a permissive environment to support neuron regeneration.

Conclusion

The ASN-BDNF transplantation provided a promising therapeutic approach to promote axonal regeneration and recovery after SCI, and can be used as part of a combinatory treatment strategy for SCI management.     

TRIM22 inhibits the TRAF6-stimulated NF-κB pathway by targeting TAB2 for degradation

Tripartite motif containing 22 (TRIM22), a member of the TRIM/RBCC family, has been reported to activate the nuclear factor-kappa B (NF-κB) pathway in unstimulated macrophage cell lines, but the detailed mechanisms governing this activation remains unclear. We investigated this mechanism in HEK293T cells. We found that overexpression of TRIM22 could activate the NF-κB pathway and conversely, could inhibit the tumor necrosis factor receptor-associated factor 6 (TRAF6)-stimulated NF-κB pathway in HEK293T cells. Further experiments showed that TRIM22 could decrease the self-ubiquitination of TRAF6, and interact with and degrade transforming growth factor-β activated kinase 1 binding protein 2 (TAB2), and that these effects could be partially rescued by a TRIM22 RING domain deletion mutant. Collectively, our data indicate that overexpression of TRIM22 may negatively regulate the TRAF6-stimulated NF-κB pathway by interacting with and degrading TAB2.     

白念珠菌钙稳态系统及钙信号途径的研究进展

白念珠菌是临床重要的条件致病菌,其胞内的钙稳态及钙信号途径与宿主侵染、压力应答等诸多生理过程紧密相关。研究该菌的钙稳态系统及钙信号调控网络,对明确白念珠菌的侵染机制与耐药机理,以及开发具有新靶点的抗真菌药物具有重要意义。本文对这些内容的研究进展进行了综述。     

Biochemical characterization of indole prenyltransferases: filling the last gap of prenylation positions by a 5-dimethylallyltryptophan synthase from Aspergillus clavatus

The putative prenyltransferase gene ACLA_031240 belonging to the dimethylallyltryptophan synthase superfamily was identified in the genome sequence of Aspergillus clavatus and overexpressed in Escherichia coli. The soluble His-tagged protein EAW08391 was purified to near homogeneity and used for biochemical investigation with diverse aromatic substrates in the presence of different prenyl diphosphates. It has shown that in the presence of dimethylallyl diphosphate (DMAPP), the recombinant enzyme accepted very well simple indole derivatives with L-tryptophan as the best substrate. Product formation was also observed for tryptophan-containing cyclic dipeptides but with much lower conversion yields. In contrast, no product formation was detected in the reaction mixtures of L-tryptophan with geranyl or farnesyl diphosphate. Structure elucidation of the enzyme products by NMR and MS analyses proved unequivocally the highly regiospecific regular prenylation at C-5 of the indole nucleus of the simple indole derivatives. EAW08391 was therefore termed 5-dimethylallyltryptophan synthase, and it filled the last gap in the toolbox of indole prenyltransferases regarding their prenylation positions. K(m) values of 5-dimethylallyltryptophan synthase were determined for L-tryptophan and DMAPP at 34 and 76 μM, respectively. Average turnover number (k(cat)) at 1.1 s(-1) was calculated from kinetic data of L-tryptophan and DMAPP. Catalytic efficiencies of 5-dimethylallyltryptophan synthase for L-tryptophan at 25,588 s(-1)·M(-1) and for other 11 simple indole derivatives up to 1538 s(-1)·M(-1) provided evidence for its potential usage as a catalyst for chemoenzymatic synthesis.     

深圳红树林区浮游植物时空变化与水质要素的关系

在探讨深圳福田红树林区浮游植物群落结构及种群数量变化规律的基础上,对红树林区不同水质环境中浮游植物时空变化进行了研究,初步分析主要水质因子与浮游植物密度时空变化的相关关系。分析表明,福田红树林区浮游植物有5门28属51种(含未知9种),以硅藻门种类为主,优势种为微小小环藻(Cyclotella caspia)和诺氏海链藻(Thalassiosira nordenskiöldi)等,蓝藻、绿藻能发展成为优势类群,优势种为小颤藻(Oscillatoria minima)和小球藻(Chlorella vulgaris)等。浮游植物种类组成季节变化明显,空间变化显著。浮游植物密度空间变化明显,季节差异不大。各季度的浮游植物密度较高,达到106cells·L^-1的级别。由于接纳生活污水、工业废水、养殖废水等陆源污水,5个站位的主要水质因子受污水排放影响明显,站位受陆源污水影响的顺序依次为:Ⅳ>Ⅱ>Ⅴ>Ⅰ>Ⅲ,污水排放进入红树林区的水域水质显著区别于完全海水水域。陆源污水输入对浮游植物密度时空变化造成显著影响,浮游植物密度与总氮浓度、盐度相关性较好,与总氮成显著负相关,与盐度成显著正相关。