Identification of two novel type 1 peroxisomal targeting signals in Arabidopsis thaliana

Peroxisomes lack their own genetic material and must therefore import proteins encoded by genes in the nucleus. Amino acids within these proteins serve as targeting signals: they direct the delivery of the proteins to the organelle. The majority of soluble proteins destined for the peroxisomal matrix utilize a type 1 peroxisomal targeting signal (PTS1): a C-terminal tripeptide that follows the pattern small/basic/hydrophobic. We have discovered two new C-terminal tripeptides that target proteins to peroxisomes in Arabidopsis thaliana. The tripeptides PSL and KRR do not fit the major PTS1 consensus but cause green fluorescent protein to accumulate in peroxisomes of stably transformed Arabidopsis. We have identified forty-one proteins in the Arabidopsis genome that also bear these tripeptides at their C-termini and may therefore be peroxisomal.     

4-苯基-1,3,5-三嗪-2-胺类衍生物的合成及其体外抗肿瘤活性研究

目的以IMC-038525为先导化合物,设计并合成4-苯基-1,3,5-三嗪-2-胺类化合物,考察其体外抗肿瘤活性。方法以2,4-二氯-1,3,5-三嗪为起始原料,经过氨化、Suzuki偶联和还原胺化合成一类4-苯基-1,3,5-三嗪-2-胺类化合物,采用噻唑蓝法(MTT)测定其对肿瘤细胞的抑制活性。结果设计并合成了13个新化合物,结构经1H-NMR和MS确证。活性测试结果显示该类化合物具有一定的抗肿瘤活性。结论合成了一类4-苯基-1,3,5-三嗪-2-胺类衍生物,具有一定抑瘤活性的化合物,为新型抗肿瘤化合物的设计与合成提供思路。     

Follow-up of blood-pressure lowering and glucose control in type 2 diabetes

In the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation(ADVANCE) factorial trial, the combination of perindopril and indapamide reduced mortality among patients with type 2 diabetes, but intensive glucose control, targeting a glycated hemoglobin level of less than6.5%, did not. We now report results of the 6-year post-trial follow-up. Methods We invited surviving participants, who had previously been assigned to perindopril-indapamide or placebo and to intensive or standard glucose control(with the glucose-control comparison extending for an additional 6 months), to participate in apost-trial follow-up evaluation. The primary end points were death from any cause and major macrovascular events. Results The baseline characteristics were similar among the 11,140 patients who originally underwent randomization and the 8494 patients who participated in the post-trial follow-up for a median of 5.9 years(blood-pressure-lowering comparison) or 5.4 years(glucose-control comparison). Between-group differences in blood pressure and glycated hemoglobin levels during the trial were no longer evident by the first post-trial visit. The reductions in the risk of death from any cause and of death from cardiovascular causes that had been observed in the group receiving active blood-pressure-lowering treatment during the trial were attenuated but significant at the end of the post-trial follow-up; the hazard ratios were 0.91(95% confidence interval [CI],0.84 to 0.99; P = 0.03) and 0.88(95% CI, 0.77 to 0.99; P = 0.04), respectively. No differences were observed during follow-up in the risk of death from any cause or major macrovascular events between the intensive-glucose-control group and the standard-glucose-control group; the hazard ratios were 1.00(95% CI, 0.92 to 1.08) and 1.00(95% CI, 0.92 to 1.08), respectively. Conclusion The benefits with respect to mortality that had been observed among patients originally assigned to blood-pressure-lowering therapy were attenuated but still evident at the end of follow-up. There was no evidence that intensive glucose control during the trial led to long-term benefits with respect to mortality or macrovascular events.     

牙龈卟啉单胞菌PG0839基因突变株的构建

目的构建牙龈卟啉单胞菌毒力岛基因PG0839突变菌株,为研究PG0839基因功能提供实验基础。方法扩增1 584 bp PG0839基因片段,对聚合酶链反应（PCR）产物和pUC19载体进行BamH Ⅰ和EcoRⅠ双酶切,连接酶切产物得到质粒pPG0839-1。将2 101 bp erm基因产物插入到pPG0839-1中PG0839基因的EcoRⅤ位点,构建质粒pPG0839-2,作为电穿孔的供体质粒。电穿孔转化于受体菌牙龈卟啉单胞菌W83菌株,红霉素抗性培养基筛选阳性克隆,命名为PG0839基因突变菌株。结果运用插入失活方法构建PG0839基因突变菌株,进而通过酶切、测序、PR和反转录PCR对PG0839基因突变菌株进行验证,证实PG0839基因突变菌株构建成功。结论本实验成功构建PG0839基因突变菌株。     

In vivo bioluminescence imaging of magnetically targeted bone marrow‐derived mesenchymal stem cells in skeletal muscle injury model

The purpose of this study is to clarify the kinetics of transplanted mesenchymal stem cells (MSCs) in rat skeletal muscle injury model and the contribution of the magnetic cell delivery system to muscle injury repair. A magnetic field generator was used to apply an external magnetic force to the injury site of the tibia anterior muscle, and 1 × 10⁶ MSCs labeled with ferucarbotran–protamine complexes, which were isolated from luciferase transgenic rats, were injected into the injury site. MSCs were injected with and without an external magnetic force (MSC M+ and MSC M? groups, respectively), and phosphate‐buffered saline was injected into injury sites as a control. In vivo bioluminescence imaging was performed immediately after the transplantation and, at 12, 24, and 72 h, and 1 and 4 weeks post‐transplantation. Also, muscle regeneration and function were histologically and electromechanically evaluated. In vivo bioluminescence imaging showed that the photon of the MSC M+ group was significantly higher than that of the MSC M? group throughout the observation period. In addition, muscle regeneration and function in the MSC M+ group was histologically and functionally better than that of the MSC M? group. The results of our study indicated that magnetic cell delivery system may be of use in directing the transplanted MSCs to the injury site to promote skeletal muscle regeneration. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 754–759, 2013     

Circuit mechanisms of GluA1‐dependent spatial working memory

Spatial working memory (SWM), the ability to process and manipulate spatial information over a relatively short period of time, requires an intact hippocampus, but also involves other forebrain nuclei in both in rodents and humans. Previous studies in mice showed that the molecular mechanism of SWM includes activation of AMPA receptors containing the GluA1 subunit (encoded by gria1) as GluA1 deletion in the whole brain (gria1^–/–) results in strong SWM deficit. However, since these mice globally lack GluA1, the circuit mechanisms of GluA1 contribution to SWM remain unknown. In this study, by targeted expression of GluA1 containing AMPA receptors in the forebrain of gria1^–/– mice or by removing GluA1 selectively from hippocampus of mice with “floxed” GluA1 alleles (gria1^fl/fl), we show that SWM requires GluA1 action in cortical circuits but is only partially dependent on GluA1‐containing AMPA receptors in hippocampus. We further show that hippocampal GluA1 contribution to SWM is temporally restricted and becomes prominent at longer retention intervals (≥30 s). These findings provide a novel insight into the neural circuits required for SWM processing and argue that AMPA mediated signaling across forebrain and hippocampus differentially contribute to encoding of SWM. © 2013 Wiley Periodicals, Inc.     

Cell-penetrating peptides with intracellular organelle targeting

Introduction: One of the major limiting steps in order to have an effective drug is the passage through one or more cell membranes to reach its site of action. To reach the action-site, the specific macromolecules are required to be delivered specifically to the cell compartment/organelle in their (pre)active form.

Areas covered: In this review, we will discuss cell-penetrating peptides (CPPs) developed in the last decade to transport small RNA/DNA, plasmids, antibodies, and nanoparticles into specific sites of the cell. The article describes CPPs in complex with cargo molecules that target specific intracellular organelles and their potential for pharmacological or clinical use.

Expert opinion: Organelle targeting is the ultimate goal to ensure selective delivery to the site of action in the cells. CPP technologies represent an important strategy to address drug delivery to specific intracellular compartments by covalent conjugation to targeting sequences, potentially enabling strategies to combat genomic diseases as well as infections, cancer, neurodegenerative and hereditary diseases. They have proven to be successful in delivering various therapeutic agents into cells however, further in vivo experiments and clinical trials are required to demonstrate the efficacy of this technology.     

非酒精性脂肪性肝病的联合疗法和递送策略

非酒精性脂肪性肝病（non-alcoholic fatty liver disease,NAFLD）是与代谢功能障碍密切相关的一系列慢性肝病,其发病机制复杂,至今仅有一款PPAR-α/γ双重激动剂Saroglitazar上市,用于治疗非肝硬化非酒精性脂肪性肝炎。针对NAFLD发病机制中的相同或不同靶点和信号通路开发的联合治疗策略能有望实现药物与药物间的协同作用,小分子药物联用、RNAi联合疗法和化学基因疗法是目前极富前景的联合治疗策略。此外,设计安全、有效和特异性的药物递送系统能改善小分子药物与基因药物的成药性,并促进其临床转化和产业化。因此,本文介绍了小分子药物联用、基于RNAi的核酸药物联用和小分子与核酸药物联用的最新研发现状及其递送方式,以期为NAFLD的治疗提供新的思路与方法。     

间充质干细胞在肿瘤靶向递药系统中的应用

间充质干细胞(mesenchymal stem cells,MSCs)是干细胞家族的重要成员,来源于发育早期的中胚层和外胚层,属于多能干细胞,由于其具有分化潜力大、增殖能力强、免疫原性低、肿瘤部位趋向性、取材方便、易于工业化制备等特征,有可能成为最具临床应用前景的多能干细胞。本文介绍间充质干细胞的基本特性以及其在肿瘤靶向递药系统中的研究进展、临床应用现状,为间充质干细胞在肿瘤靶向递药系统中的进一步研究提供依据。