miR-106a-5p调控 PTEN对鼻咽癌细胞SUNE2增殖和迁移的抑制作用研究

目的研究miR-106a-5p对鼻咽癌细胞SUNE2增殖和迁移的影响。 方法将体外培养的鼻咽癌细胞SUNE2分成对照组（细胞未做任何处理）、Anti-NC组（转染阴性对照抑制剂）、Anti-miR-106a-5p组（转染miR-106a-5p抑制剂）、后期实验另设Anti-miR-106a-5p-inhibitor+si-NC组（转染miR-106a-5p抑制剂、siRNA阴性对照）、Anti-miR-106a-5p-inhibitor+si-PTEN组（转染miR-106a-5p抑制剂、PTEN siRNA）,采用Realtime PCR测定miR-106a-5p表达,MTT法检测增殖,Transwell小室检测细胞侵袭和迁移能力变化,用Western blot方法测定vimentin、E-cadherin蛋白表达。在线靶基因预测软件预测miR-106a-5p的靶基因可能为PTEN,双荧光素酶报告系统鉴定miR-106a-5p和PTEN的靶向关系。两组间比较用独立样本t检验,多组间比较采用单因素方差分析,组间两两比较采用LSD-t检验。 结果与正常鼻咽上皮细胞NP69比较,鼻咽癌细胞CNE-2、HK1、SUNE2中miR-106a-5p水平（1.00±0.11比1.84±0.13、2.19±0.14、2.87±0.25）升高,差异具有统计学意义（P < 0.05）。与对照组、Anti-NC组比较,Anti-miR-106a-5p组鼻咽癌细胞miR-106a-5p水平（1.00±0.10、0.99±0.12比0.76±0.08）降低,OD值（0.56±0.05、0.57±0.04比0.32±0.02）,细胞侵袭数[（128.47±11.65）个、（129.84±10.93）个比（85.12±6.75）个],迁移数[（182.51±14.81）个、（180.68±17.64）个比（122.01±11.62）个],vimentin蛋白表达水平（0.84±0.09、0.82±0.07比0.30±0.05）降低,E-cadherin蛋白表达水平（0.29±0.04、0.28±0.05比0.76±0.08）升高,差异具有统计学意义（P均< 0.05）。与Anti-miR-106a-inhibitor+si-NC组比较,Anti-miR-106a-inhibitor+si-PTEN组细胞OD值（0.33±0.03比0.52±0.05）、侵袭数[（84.16±5.91）个比（105.79±8.63）个]、迁移数[（118.42±10.25）个比（164.28±12.05）个]、vimentin蛋白表达水平（0.34±0.06比0.68±0.05）均升高,E-cadherin蛋白表达水平（0.72±0.06比0.29±0.05）降低,差异具有统计学意义（P均< 0.05）。 结论miR-106a-5p可通过靶向调控PTEN抑制鼻咽癌细胞SUNE2增殖和迁移潜能。     

Helix-coil transition of PrP106-126: molecular dynamic study.

A set of 34 molecular dynamic (MD) simulations totaling 305 ns of simulation time of the prion protein-derived peptide PrP106-126 was performed with both explicit and implicit solvent models. The objective of these simulations is to investigate the relative stability of the alpha-helical conformation of the peptide and the mechanism for conversion from the helix to a random-coil structure. At neutral pH, the wild-type peptide was found to lose its initial helical structure very fast, within a few nanoseconds (ns) from the beginning of the simulations. The helix breaks up in the middle and then unwinds to the termini. The spontaneous transition into the random coil structure is governed by the hydrophobic interaction between His(111) and Val(122). The A117V mutation, which is linked to GSS disease, was found to destabilize the helix conformation of the peptide significantly, leading to a complete loss of helicity approximately 1 ns faster than in the wild-type. Furthermore, the A117V mutant exhibits a different mechanism for helix-coil conversion, wherein the helix begins to break up at the C-terminus and then gradually to unwind towards the N-terminus. In most simulations, the mutation was found to speed up the conversion through an additional hydrophobic interaction between Met(112) and the mutated residue Val(117), an interaction that did not exist in the wild-type peptide. Finally, the beta-sheet conformation of the wild-type peptide was found to be less stable at acidic pH due to a destabilization of the His(111)-Val(122), since at acidic pH this histidine is protonated and is unlikely to participate in hydrophobic interaction.     

Structure of Porriolide,a New Metabolite from Alternaria porri

Compounds from a soil isolate of Penicillium sp. MG-11 showed remarkable convulsive activity against silkworms. Activity-based fractionation of an acetone extract of the fermentation products resulted in the isolation of four compounds. One was identified as verruculogen, which was an active principle. Another compound, acetoxydehydroaustin, was new and was structurally characterized by spectral data and a single-crystal X-ray analysis. The two other compounds were identified as dehydroaustin and austin on the basis of the spectral data. Although the latter three compounds were not active themselves, they enhanced the convulsive activity of verruculogen in a silkworm bioassay. Three additional compounds with no identifiable activity were also isolated. Two of them were identified as austinol and dehydroaustinol, and the third was determined to be a new related compound named neoaustin by an X-ray analysis of crystals.     

Gating in iodate-modified single cardiac Na+ channels

Summary Elementary Na⁺ currents were recorded at 19°C during 220-msec lasting step depolarizations in cell-attached and inside-out patches from cultured neonatal rat cardiocytes in order to study the modifying influence of iodate, bromate and glutaraldehyde on single cardiac Na⁺ channels.Iodate (10 mmol/liter) removed Na⁺ inactivation and caused repetitive, burst-like channel activity after treating the cytoplasmic channel surface. In contrast to normal Na⁺ channels under control conditions, iodate-modified Na⁺ channels attain two conducting states, a short-lasting one with a voltage-independent lifetime close to 1 msec and, likewise tested between –50 and +10 mV, a long-lasting one being apparently exponentially dependent on voltage. Channel modification by bromate (10 mmol/liter) and glutaraldehyde (0.5 mmol/liter) also included the occurrence of two open states. Also, burst duration depended apparently exponentially on voltage and increased when shifting the membrane in the positive direction, but there was no evidence for two bursting states. Chemically modified Na⁺ channels retain an apparently normal unitary conductance (12.8±0.5 pS). Of the two substates observed, one of them is remarkable in that it is mostly attained from full-state openings and is very short living in nature; the voltage-independent lifetime was close to 2 msec. Despite removal of inactivation, open probability progressively declined during membrane depolarization. The underlying deactivation process is strongly voltage sensitive but, in contrast to slow Na⁺ inactivation, responds to a voltage shift in the positive direction with a retardation in kinetics. Chemically modified Na⁺ channels exhibit a characteristic bursting state much shorter than in DPI-modified Na⁺ channels, a difference not consistent with the hypothesis of common kinetic properties in noninactivating Na⁺ channels.     

Evidences for correlation between the reduced VCAM-1 expression and hyaluronan synthesis during cellular senescence of human mesenchymal stem cells

Mesenchymal stem cells (MSCs) undergo cellular senescence during in vitro expansion culture, which accompanies the loss of migration and homing abilities. In this study, we analyzed expression levels of several surface markers of human MSCs at different passages of expansion culture. It has been shown that expression of vascular cell adhesion molecule-1 (VCAM-1) was most markedly decreased among the tested markers in the senescent MSCs. Interestingly the reduced VCAM-1 expression could be restored by applying hyaluronan, a major glycosaminoglycan ligand of CD44, to the culture. It was found that the hyaluronan level in extracellular and pericellular matrices was greatly reduced in the senescent MSCs, mainly due to the decreased expression of hyaluronan synthases, suggesting a correlation between the reduced VCAM-1 expression and hyaluronan synthesis. In fact, when hyaluronan synthases were knock-downed by siRNA transfection, the VCAM-1 expression was also reduced. Our results indicate that VCAM-1 expression in the senescent MSCs was down-regulated because of the reduced synthesis of hyaluronan. Thus, we suggest that hyaluronan supplementation in expansion culture of MSCs would compensate adverse effects induced by its decreased synthesis and subsequently enhance cell adhesion and migration abilities.     

Antiaggregating antibody raised against human PrP 106-126 recognizes pathological and normal isoforms of the whole prion protein

Antibodies to the prion protein (PrP) have been critical to the neuropathological and biochemical characterization of PrP-related degenerative diseases in humans and animals. Although PrP is highly conserved evolutionarily, there is some sequence divergence among species; as a consequence, anti-PrP antibodies have a wide spectrum of reactivity when challenged with PrP from diverse species. We have produced an antibody [monoclonal antibody (mAb) 2-40] raised against a synthetic peptide corresponding to residues (106-126 of human PrP and have characterized it by epitope mapping, Western immunoblot analysis, and immunohistochemistry. The antibody recognizes not only human PrP isoforms but also pathological PrP from all species tested (i.e., sheep, hamsters, and mice). Together with the fact that it recognizes the whole PrP in both cellular and scrapie isoforms, mAb 2-40 may be helpful in studying conformational changes of the PrP, as well as establishing a possible connection between human and animal diseases.     

Custom-designed Laser-based Heating Apparatus for Triggered Release of Cisplatin from Thermosensitive Liposomes with Magnetic Resonance Image Guidance

Liposomes have been employed as drug delivery systems to target solid tumors through exploitation of the enhanced permeability and retention (EPR) effect resulting in significant reductions in systemic toxicity. Nonetheless, insufficient release of encapsulated drug from liposomes has limited their clinical efficacy. Temperature-sensitive liposomes have been engineered to provide site-specific release of drug in order to overcome the problem of limited tumor drug bioavailability. Our lab has designed and developed a heat-activated thermosensitive liposome formulation of cisplatin (CDDP), known as HTLC, to provide triggered release of CDDP at solid tumors. Heat-activated delivery in vivo was achieved in murine models using a custom-built laser-based heating apparatus that provides a conformal heating pattern at the tumor site as confirmed by MR thermometry (MRT). A fiber optic temperature monitoring device was used to measure the temperature in real-time during the entire heating period with online adjustment of heat delivery by alternating the laser power. Drug delivery was optimized under magnetic resonance (MR) image guidance by co-encapsulation of an MR contrast agent (i.e., gadoteridol) along with CDDP into the thermosensitive liposomes as a means to validate the heating protocol and to assess tumor accumulation. The heating protocol consisted of a preheating period of 5 min prior to administration of HTLC and 20 min heating post-injection. This heating protocol resulted in effective release of the encapsulated agents with the highest MR signal change observed in the heated tumor in comparison to the unheated tumor and muscle. This study demonstrated the successful application of the laser-based heating apparatus for preclinical thermosensitive liposome development and the importance of MR-guided validation of the heating protocol for optimization of drug delivery.     

miR-106-363基因簇在脊椎动物中的进化分析

microRNA(miRNA)是一类在真核生物体内广泛表达的非编码小分子RNA,在生物体生长、发育以及疾病发生等过程中都起着极其重要的作用。miR-106-363基因簇是一个高度保守的基因簇,编码miR-106、miR-18、miR-20、miR-19、miR-92和miR-363等6个miRNA。本文通过对miRBase数据库检索以及同源搜索的方法在16种脊椎动物中搜索到了miR-106-363基因簇。该miRNA基因簇在高等脊椎动物中高度保守,稳定存在。系统进化树分析表明,miR-106-363基因簇与miR-17-92基因簇有着共同的祖先,且在进化上miR-17-92基因簇有着更早的起源。     

Comparative genomics analysis of Clostridium difficile epidemic strain DH/NAP11/106

Clostridium difficile PCR ribotype 106 (also identified as restriction endonuclease analysis [REA] group DH) recently emerged as the most common strain causing C. difficile infection (CDI) among US adults. We previously identified this strain predominating our pediatric cohort. Pediatric clinical CDI isolates previously characterized by REA underwent antibiotic resistance testing and whole genome sequencing. Of 134 isolates collected from children, 31 (23%) were REA group DH. We performed a comparative genomics analysis to identify DH-associated accessory genes. We identified five DH-associated genes that are associated with virulence in other bacterial species but not previously known to contribute to CDI. These genes are associated with intestinal mucosal adhesion (collagen-binding surface protein), sporulation (sporulation integral membrane protein YtvI), and protection from oxidative stress and foreign DNA (DNA phosphorothioation-dependent restriction proteins, sulfurtransferase, and DNA sulfur modification proteins). The association of these genes was validated in a cohort of 623 publicly available C. difficile sequences, 10 (1.6%) of which were monophyletic to REA group DH through in silico multilocus sequence typing and core genome phylogenetic analysis. Further investigation is required to determine the contribution of these genes to the emergence and virulence of this epidemic strain.