The Co-Chaperone Hch1 Regulates Hsp90 Function Differently than Its Homologue Aha1 and Confers Sensitivity to Yeast to the Hsp90 Inhibitor NVP-AUY922

Hsp90 is a dimeric ATPase responsible for the activation or maturation of a specific set of substrate proteins termed ‘clients’. This molecular chaperone acts in the context of a structurally dynamic and highly regulated cycle involving ATP, co-chaperone proteins and clients. Co-chaperone proteins regulate conformational transitions that may be impaired in mutant forms of Hsp90. We report here that the in vivo impairment of commonly studied Hsp90 variants harbouring the G313S or A587T mutation are exacerbated by the co-chaperone Hch1p. Deletion of HCH1, but not AHA1, mitigates the temperature sensitive phenotype and high sensitivity to Hsp90 inhibitor drugs observed in Saccharomyces cerevisiae that express either of these two Hsp90 variants. Moreover, the deletion of HCH1 results in high resistance to Hsp90 inhibitors in yeast that express wildtype Hsp90. Conversely, the overexpression of Hch1p greatly increases sensitivity to Hsp90 inhibition in yeast expressing wildtype Hsp90. We conclude that despite the similarity between these two co-chaperones, Hch1p and Aha1p regulate Hsp90 function in distinct ways and likely independent of their roles as ATPase stimulators. We further conclude that Hch1p plays a critical role in regulating Hsp90 inhibitor drug sensitivity in yeast.     

几种常用杀虫剂对蚜虫天敌——瓢虫的影响

作者等就11种常用杀虫剂对蚜虫的重要天敌——瓢虫进行了毒性测定,观察了它们对瓢虫的各个虫态的影响。 供试药剂 20％乐果乳剂、50％敌敌畏乳剂、50％对硫磷乳剂、50％内吸磷乳剂、25％三硫磷乳剂、50％杀螟硫磷乳剂、50％磷胺液剂、20％酚开普敦乳剂、6％丙体六六六乳剂、6％丙体六六六可湿性粉(W、P)、2.5％鱼籐精乳剂。 供试瓢虫 异色瓢虫Leis axyridis,室内饲养;龟纹瓢虫Propylaea japonica,田间采回。     

Purification and characterization of two β-N-acetylhexosaminidases from the tobacco hornworm,Manduca sexta (L.) (Lepidoptera: Sphingidae)

β-N-Acetylhexosaminidases were detected in 10 insects including species of Lepidoptera, Coleoptera, Hemiptera, and Orthoptera. Two enzymes were purified from the tobacco hornworm, Manduca sexta (L.). EI was detected in larval and pharate pupal molting fluid, integument, and pupal hemolymph while EII was found in larval and pupal hemolymphs. They are acidic hydrolases with similar molecular weights (6.1 × 10⁴), molar extinction coefficients at 280 nm (1.9 × 10⁵ liters mol^?1 cm^?1), and pH optima (pH 6). They differ in the number of polypeptide chains per molecule (EI is a single chain and EII consists of two polypeptide chains), amino acid composition, extent of glycosylation (EII is probably a glycoprotein), isoelectric point (pI_EI = 5.9 and pI_EII ～- 5.1), tissue distribution, and reactivities toward nitrophenylated N-acetylglucosamine (k_cat,I = 328 s^?1 and k_cat,II = 103 s^?1) and N,N′-diacetylchitobiose (k_cat,I = 307 s^?1 and k_cat,II = 3 s^?1). These results suggest that EI is a chitinase and that EII may function as a hexosaminidase in vivo.     

3D nuclear organization of telomeres in the Hodgkin cell lines U-HO1 and U-HO1-PTPN1: PTPN1 expression prevents the formation of very short telomeres including "t-stumps"

Background  

In cancer cells the three-dimensional (3D) telomere organization of interphase nuclei into a telomeric disk is heavily distorted and aggregates are found. In Hodgkin's lymphoma quantitative FISH (3D Q-FISH) reveals a major impact of nuclear telomere dynamics during the transition form mononuclear Hodgkin (H) to diagnostic multinuclear Reed-Sternberg (RS) cells. In vitro and in vivo formation of RS-cells is associated with the increase of very short telomeres including "t-stumps", telomere loss, telomeric aggregate formation and the generation of "ghost nuclei".     

The p16INK4a tumor suppressor controls p21WAF1 induction in response to ultraviolet light

p16^INK4a and p21^WAF1, two major cyclin-dependent kinase inhibitors, are the products of two tumor suppressor genes that play important roles in various cellular metabolic pathways. p21^WAF1 is up-regulated in response to different DNA damaging agents. While the activation of p21^WAF1 is p53-dependent following γ-rays, the effect of ultraviolet (UV) light on p21^WAF1 protein level is still unclear. In the present report, we show that the level of the p21^WAF1 protein augments in response to low UVC fluences in different mammalian cells. This up-regulation is mediated through the stabilization of p21^WAF1 mRNA in a p16^INK4a-dependent manner in both human and mouse cells. Furthermore, using p16-siRNA treated human skin fibroblast; we have shown that p16 controls the UV-dependent cytoplasmic accumulation of the mRNA binding HuR protein. In addition, HuR immunoprecipitations showed that UV-dependent binding of HuR to p21 mRNA is p16-related. This suggests that p16 induces p21 by enabling the relocalization of HuR from the nucleus to the cytoplasm. Accordingly, we have also shown that p16 is necessary for efficient UV-dependent p53 up-regulation, which also requires HuR. These results indicate that, in addition to its role in cell proliferation, p16^INK4a is also an important regulator of the cellular response to UV damage.     

Synthesis of N-tetra-O-acetyl-β-d-glucopyranosyl-N′-(4′,6′-diarylpyrimidin-2′-yl)thioureas

Some 2-amino-4,6-diarylpyrimidines 2 have been prepared from substituted benzylideneacetophenones and guanidine hydrochloride in the presence of alkali by conventional heating in alcoholic medium and microwave heating in solvent-free conditions. N-(2,3,4,6-Tetra-O-acetyl-β-d-glucopyranosyl)-N′-(4′,6′-diarylpyrimidin-2′-yl)thioureas 4 have been synthesized by reaction of per-O-acetylated glucopyranosyl isothiocyanate 1 and substituted 2-amino-4,6-diarylpyrimidines 2. Two different methods have been used, namely, refluxing in anhydrous dioxane and solvent-free microwave-assisted coupling. The second procedure afforded higher yields in much shorter reaction times. The compounds 2 and 4 were tested for their antibacterial and antifungal activities in vitro against Staphylococcus epidermidis, Enterobacter aerogenes and Candida albicans by disc diffusion method.     

核定位信号肽提高核糖体区打靶载体转染效率的研究

核糖体区打靶载体(10～14 kb)是中南大学医学遗传学国家重点实验室构建的一种具有定点整合能力的非病毒载体,具有安全性好及长期稳定表达的特点,但是较低的转染率成为其应用于临床的主要障碍．核定位信号肽可以促进非病毒载体进入细胞核,从而提高其转染效率．但是核定位信号肽提高外源基因表达的能力却严重受到其与DNA偶联方式及偶联剂的影响．采用偶联剂SPB可以通过静电作用将核糖体区打靶载体与SV40 核定位信号肽有效结合,并且可以防止其被DNase降解．应用聚乙烯亚胺转染人原代皮肤成纤维细胞后,激光共聚焦显微镜观察显示,核定位信号肽可以在60 min内携带12 kb的质粒DNA进入细胞核．转染后48 h,流式细胞仪检测GFP表达,结果显示转染率提高了4～5倍．聚乙烯亚胺是一种毒性小,而且价格低廉的高分子转染试剂,广泛被应用于体内基因治疗的研究中,上述研究将会促进核糖体区打靶载体在临床基因治疗中的应用．     

Anti-tumor effects of fusion vaccine prepared by renal cell carcinoma 786-O cell line and peripheral blood dendritic cells of healthy volunteers in vitro and in human immune reconstituted SCID mice

Dendritic cells (DC), as professional antigen presenting cells, play the central role in the process of body initiating the anti-tumor immunity, and the study on DC anti-tumor vaccine has become heated in recent years. In this study, we used polyethylene glycol (PEG) to induce renal cell carcinoma (RCC) 786-O cell line fused with peripheral blood DC of healthy volunteers, and discuss the biological characteristics of fusion vaccine and its anti-tumor effects in vitro and in human immune reconstituted SCID mice model of RCC. The study found that PEG could effectively induce cell fusion, and the expressions of CD86 and HLA-DR in fusion vaccine group were significantly up-regulated compared with the DC control group; the secretion of IL-12 was much higher and longer than that of the control; the functions of dendritic cell-tumor fusion vaccine to stimulate the proliferation of allogenic T lymphocytes and to kill RCC786-O cells in vitro were significantly higher than those of the control group, and after the killing, apoptosis body was observed in the target cells; after the injection of fusion vaccine into human immune reconstituted SCID mice model of RCC786-O via vena caudalis, the volume of mice tumor was reduced significantly, proliferation index of tumor cells decreased obviously compared with that of the control group, and more hemorrhage and putrescence focuses presented, accompanying large quantity of lymphocytes soakage. The results of this experimental study shows that fusion vaccine of RCC786-O cell line and DC can significantly stimulate the proliferation of allogenic T cells and specifically inhibit and kill RCC cells in vitro and in vivo, which makes the DC-RCC786-O fusion vaccine a possible new way of effective RCC immunotherapy.     

Monolithic Endocrown Vs. Hybrid Intraradicular Post/Core/Crown Restorations for Endodontically Treated Teeth; Cross-sectional Study

The gold standard for restoring Endodontically Treated Teeth (ETT) with successful clinical longevity requires having minimal invasive preparations and maximal tissue conservation. Many dentists still consider hybrid post/core/crown to be the first choice for restoring ETT. Endocrown is a viable alternative treatment modality to hybrid post/core/crown. This study aims to assess the proper judgment of dentists working in Riyadh, Saudi Arabia on the use of monolithic endocrown versus hybrid post/core/crown for restoring ETT. The IRB of Princess Nourah Bint Abdulrahman University (PNU) Institutional Review Board reviewed this study. The questionnaire was validated and electronically distributed. The participants were pre-informed that their responses are completely anonymous and used for professional purposes only. The questionnaire surveyed dentists working in Riyadh, Saudi Arabia, about their preference for different ETT restorative modalities at various clinical scenarios. Data were analyzed using One-way ANOVA and t-test. All P-values of < 0.05 were considered statistically significant. A total of 275 responses were collected; 61.45% were females and 38.55% males. 56% of them were general practitioners, while 16% were consultants. Prefabricated post/core was the most preferred technique among the participants (18.55%), followed by endocrown (12.36%), and lastly, cast post/core (8.73%). The amount of remaining tooth structure was the most influential in the treatment selection (30.18%), followed by the presence or absence of 1–2 mm ferrule (17.82%). Interocclusal space (12.36%) was the least influential factor. Endocrown recorded 63.27% as the most preferred line of treatment in case of insufficient inter-occlusal space. 40.36% preferred endocrown for patients with occlusal risk factors. The amount of the remaining tooth structure and the tooth position significantly affect the treatment options of the participants. Endocrown was the most preferred treatment modality for restoring ETT for patients with occlusal consideration.