世界生命科學前沿動態(tài)周報（五十四）

（8.22-8.28/2011）
美寶國際集團:陶國新  

    主要內(nèi)容：廣譜抗病毒方法；在體外單向應力誘導血管內(nèi)皮細胞形成血管樣結(jié)構(gòu)；通過翻譯后合成磷酸絲氨酸擴展大腸桿菌遺傳密碼；代謝綜合癥病人脂肪組織調(diào)節(jié)異常更易造成糖尿病和心血管疾?。煌挥|小囊的分子構(gòu)成有所不同；Hsp90-Cdc37伴侶復合物調(diào)節(jié)線粒體自吞噬。

焦點動態(tài)：廣譜抗病毒方法。

1. 廣譜抗病毒方法
【動態(tài)】
目前的抗病毒藥物還不多，而且大部分現(xiàn)有藥物是高度病原體特異性的，或者有其他缺陷。美國MIT的科學家研發(fā)了一種廣譜抗病毒方法，稱為雙鏈RNA激活的切冬酶寡聚體(DRACO)，能夠選擇性誘導含有病毒雙鏈RNA的細胞進行凋亡，快速消滅被感染的細胞而不影響未感染細胞。他們制造了DRACO并證明對11種哺乳動物細胞是無毒的，能夠?qū)?5種不同病毒，包括登革熱病毒和H1N1流感病毒等。他們也證明了DRACO能夠挽救感染H1N1流感病毒的老鼠。因為雙鏈RNA檢測域的廣譜的敏感性、凋亡誘導區(qū)域的高活性，以及病毒從未遭遇過的二者之間新的直接聯(lián)系，DRACO有潛力成為多種臨床主要病毒的治療或預防手段。

【點評】
選擇性的廣譜的清除被病毒感染的細胞是不錯的抗病毒策略。配合清除病毒的手段一起使用很有潛力成為臨床治療病毒感染的有效途徑。

【參考論文】
PLoS ONE 2011, 6(7): e22572. doi:10.1371/journal.pone.0022572
Broad-Spectrum Antiviral Therapeutics
Rider TH, Zook CE, Boettcher TL, et al.
Currently there are relatively few antiviral therapeutics, and most which do exist are highly pathogen-specific or have other disadvantages. We have developed a new broad-spectrum antiviral approach, dubbed Double-stranded RNA (dsRNA) Activated Caspase Oligomerizer (DRACO) that selectively induces apoptosis in cells containing viral dsRNA, rapidly killing infected cells without harming uninfected cells. We have created DRACOs and shown that they are nontoxic in 11 mammalian cell types and effective against 15 different viruses, including dengue flavivirus, Amapari and Tacaribe arenaviruses, Guama bunyavirus, and H1N1 influenza. We have also demonstrated that DRACOs can rescue mice challenged with H1N1 influenza. DRACOs have the potential to be effective therapeutics or prophylactics for numerous clinical and priority viruses, due to the broad-spectrum sensitivity of the dsRNA detection domain, the potent activity of the apoptosis induction domain, and the novel direct linkage between the two which viruses have never encountered.

2. 在體外單向應力誘導血管內(nèi)皮細胞形成血管樣結(jié)構(gòu)
【動態(tài)】
骨骼肌組織工程帶給那些由于外傷等損失肌肉的患者以再生治療的很大希望，但是推進到臨床應用還面臨不少挑戰(zhàn)。荷蘭的科學家報道了對于制造協(xié)調(diào)一致的預先供血的肌肉組織的研究。他們假設(shè)協(xié)調(diào)一致的有血供的三維結(jié)構(gòu)肌肉組織可以只通過單向應力在體外誘導生成。他們的研究顯示內(nèi)皮細胞和肌肉細胞不僅可以獨立地在水凝膠基質(zhì)的三維培養(yǎng)體系中沿著單向應力的方向排列，而且更重要的是，在共培養(yǎng)的三維架構(gòu)中內(nèi)皮細胞組織成血管結(jié)構(gòu)。引人注目的是，這些培養(yǎng)體系里不需要添加另外的生長因子就能夠誘導內(nèi)皮細胞形成血管。肌肉組織沿著一個方向收縮時形成的單向應力刺激肌肉細胞生產(chǎn)VEGF。這一伴隨有VEGF生產(chǎn)的單向應力似乎在中起關(guān)鍵作用。

【點評】
這一研究表明機械力的影響和調(diào)節(jié)是骨骼肌發(fā)育的重要因素。

【參考論文】
Tissue Engineering Part A, 2011; 110811095013006 DOI: 10.1089/ten.tea.2011.0214 Mechanoregulation of Vascularization in Aligned Tissue-Engineered Muscle: A Role for Vascular Endothelial Growth Factor
Daisy W.J. van der Schaft, Ariane C.C. van Spreeuwel, Hans C. van Assen, et al.
Skeletal muscle tissue engineering has major promise for regenerative treatment of patients suffering from muscle loss due to, for example, traumatic injury, but faces considerable challenges to progress toward clinical application. In the present study the creation of an aligned prevascularized muscle tissue was addressed. We hypothesized that an aligned vascularized three-dimensional (3D) muscle tissue can be induced in vitro by merely using uniaxial stress. The present study showed that not only do endothelial cells and muscle cells independently align in the direction of uniaxial stress in a hydrogel-based 3D culture system, but also, more importantly, the endothelial cells in the co-cultured 3D constructs organized into vascular structures. Strikingly, in these cultures no additional growth factors were needed to induce vascular formation of the endothelial cells. Vascular endothelial growth factor (VEGF) production by the muscle cells was stimulated by the uniaxial stress that develops in the tissue when constrained in one direction. This stress accompanied by VEGF production appeared to play a key role in the organization of the endothelial cells into vessel-like structures.

3. 通過翻譯后合成磷酸絲氨酸擴展大腸桿菌遺傳密碼
【動態(tài)】
O-磷酸絲氨酸是真核細胞磷酸化蛋白組中含量最多的磷酸化氨基酸（Sep），不在遺傳密碼中編碼，而是在翻譯后合成。美國科學家報道了一個工程體系，通過擁有tRNASep、SepRS和設(shè)計制造的EF-Tu （EF-Sep）的大腸桿菌變種將絲氨酸特異性的共翻譯整合到蛋白的任意位置。依賴工程再造EF-Tu來放松其質(zhì)量控制功能允許Sep-tRNASep的結(jié)合來擴展遺傳密碼。

【點評】
該生物工程體系提供了一種有效的特定位置的蛋白磷酸化手段。

【參考論文】
Science, 2011; 333 (6046): 1151-1154 DOI: 10.1126/science.1207203
Expanding the Genetic Code of Escherichia coli with Phosphoserine
Hee-Sung Park, Michael J. Hohn, Takuya Umehara, et al. 
O-Phosphoserine (Sep), the most abundant phosphoamino acid in the eukaryotic phosphoproteome, is not encoded in the genetic code, but synthesized posttranslationally. Here, we present an engineered system for specific cotranslational Sep incorporation (directed by UAG) into any desired position in a protein by an Escherichia coli strain that harbors a Sep-accepting transfer RNA (tRNASep), its cognate Sep–tRNA synthetase (SepRS), and an engineered EF-Tu (EF-Sep). Expanding the genetic code rested on reengineering EF-Tu to relax its quality-control function and permit Sep-tRNASep binding. To test our system, we synthesized the activated form of human mitogen-activated ERK activating kinase 1 (MEK1) with either one or two Sep residues cotranslationally inserted in their canonical positions (Sep218, Sep222). This system has general utility in protein engineering, molecular biology, and disease research.

4. 代謝綜合癥病人脂肪組織調(diào)節(jié)異常更易造成糖尿病和心血管疾病
【動態(tài)】
代謝綜合癥與更高的糖尿病及心血管疾病風險有聯(lián)系。已有很多研究表明在代謝綜合癥中循環(huán)中的炎癥生物標記物增多，但是很少數(shù)據(jù)關(guān)于造成這一低度炎癥的細胞來源。美國科學家研究了SC脂肪組織生物學在尚未伴有糖尿病及心血管疾病的早期代謝綜合癥中的作用。經(jīng)過知情同意后招募代謝綜合癥病人和對照組受試者，采集空腹血，活檢采集SC脂肪組織。相比對照組，代謝綜合癥病人的炎癥和胰島素抗性血液生物標記物、hsCRP、IL-6, IL-1β, 瘦素（leptin）, 血清淀粉樣蛋白A和維生素A結(jié)合蛋白4 (RBP-4) 的濃度明顯更高。代謝綜合癥病人的SC脂肪組織中，leptin, RBP-4, CRP, 血清淀粉樣蛋白A, 纖溶酶原激活物抑制劑-1，IL-1, IL-6, IL-8, 和單核細胞趨化蛋白-1水平明顯高于對照組。校正腰圍因素后，除RBP-4外其余差異依然存在。另外，相對于對照組，代謝綜合癥病人的SC脂肪組織巨噬細胞浸潤明顯增多，花冠樣結(jié)構(gòu)增多。hsCRP與體內(nèi)平衡模型評價和SC脂肪組織單核細胞趨化蛋白-1正相關(guān)，與脂聯(lián)素負相關(guān)。體內(nèi)平衡模型評價與纖溶酶原激活物抑制劑-1、RBP-4和SC脂肪組織單核細胞趨化蛋白-1正相關(guān)。他們新發(fā)現(xiàn)了代謝綜合癥病人的SC脂肪組織具有更多的花冠樣結(jié)構(gòu)特征的巨噬細胞，并造成更多細胞炎癥產(chǎn)生更多與胰島素抗性和低度炎癥相關(guān)的生物學標記物。這一偏差可能造成代謝綜合癥的進展和更高風險的糖尿病及心血管疾病。

【點評】
該研究證明患有代謝綜合癥的肥胖病人患糖尿病及心血管疾病的風險更高。

【參考論文】
The Journal of Clinical Endocrinology & Metabolism, 2011 DOI: 10.1210/jc.2011-1577
Adipose Tissue Dysregulation in Patients with Metabolic Syndrome
Andrew A. Bremer, Sridevi Devaraj, Alaa Afify, and Ishwarlal Jialal.
Context: The metabolic syndrome (MetS) is associated with increased risk of diabetes and cardiovascular disease (CVD). Numerous groups have shown increased circulating biomarkers of inflammation in MetS. However, there are scanty data on the cellular sources contributing to this low-grade inflammation.
Objective: The aim of this study was to determine the role of sc adipose tissue (SAT) biology in nascent MetS without concomitant diabetes or CVD.
Patients and Methods: Subjects with MetS and controls were recruited after informed consent. Fasting blood was collected, and SAT was obtained by biopsy.
Results: Circulating biomarkers of inflammation and insulin resistance, high-sensitivity C-reactive protein (hsCRP), IL-6, IL-1β, leptin, serum amyloid A, and retinol-binding protein-4 (RBP-4) concentrations were significantly higher in the MetS subjects than controls, whereas adiponectin concentrations were lower. In SAT, leptin, RBP-4, CRP, serum amyloid A, plasminogen activator inhibitor-1, IL-1, IL-6, IL-8, and monocyte chemotactic protein-1 (MCP-1) levels were significantly higher in MetS than controls. These differences except for RBP-4 persisted after adjusting for waist circumference. In addition, there were significantly increased numbers of macrophages infiltrating the SAT of MetS and increased numbers of crown-like structures compared with controls. hsCRP correlated positively with homeostasis model assessment and SAT MCP-1 and negatively with adiponectin. Homeostasis model assessment correlated positively with plasminogen activator inhibitor-1, RBP-4, and SAT MCP-1.
Conclusions: We make the novel observation that SAT of MetS has increased macrophage recruitment with cardinal crown-like structure features and contributes to the increased cellular inflammation that produces increased levels of biomarkers that are correlated with both insulin resistance and low-grade inflammation. These aberrations could contribute to the progression of MetS and the increased risk for diabetes and CVD.

5. 突觸小囊的分子構(gòu)成有所不同
【動態(tài)】
突觸小囊屬于兩個不同的儲蓄池，負責喚起的神經(jīng)遞質(zhì)釋放的循環(huán)池和對刺激無反應的休眠池。突觸小囊統(tǒng)一的外觀暗示其位置和與細胞骨架聯(lián)系的不同解釋它們功能上的差別。美國科學家最近發(fā)現(xiàn)v-SNARE破傷風毒素不敏感小囊相關(guān)的膜蛋白(VAMP7)與其他突觸小囊蛋白在兩個池中的分布不同，證明它們的分子組成不同。他們還發(fā)現(xiàn)循環(huán)池和休眠池會同時釋放，當去除longin區(qū)域來活化時，VAMP7影響了釋放性能。更進一步，隨著喚起的自然釋放的內(nèi)吞作用機制有所不同，特定序列給予了針對不同小囊池的靶標。研究結(jié)果提示不同內(nèi)吞機制產(chǎn)生的突觸小囊具有不同蛋白賦予小囊不同特性。

【點評】
該研究對于進一步深入了解神經(jīng)遞質(zhì)的釋放和攝取有很大幫助。

【參考論文】
Neuron, 2011; 71 (3): 474 DOI:10.1016/j.neuron.2011.06.010
v-SNARE Composition Distinguishes Synaptic Vesicle Pools
Zhaolin Hua, Sergio Leal-Ortiz, Sarah M. Foss, et al. 
Synaptic vesicles belong to two distinct pools, a recycling pool responsible for the evoked release of neurotransmitter and a resting pool unresponsive to stimulation. The uniform appearance of synaptic vesicles has suggested that differences in location or cytoskeletal association account for these differences in function. We now find that the v-SNARE tetanus toxin-insensitive vesicle-associated membrane protein (VAMP7) differs from other synaptic vesicle proteins in its distribution to the two pools, providing evidence that they differ in molecular composition. We also find that both resting and recycling pools undergo spontaneous release, and when activated by deletion of the longin domain, VAMP7 influences the properties of release. Further, the endocytosis that follows evoked and spontaneous release differs in mechanism, and specific sequences confer targeting to the different vesicle pools. The results suggest that different endocytic mechanisms generate synaptic vesicles with different proteins that can endow the vesicles with distinct properties.

6. Hsp90-Cdc37伴侶復合物調(diào)節(jié)線粒體自吞噬
【動態(tài)】
自吞噬，細胞的主要回收利用再循環(huán)途徑，對于在正常生長條件下和細胞應激時保證線粒體的質(zhì)量起關(guān)鍵作用。Hsp90-Cdc37伴侶復合物協(xié)調(diào)調(diào)節(jié)所選激酶的活性來指揮應激反應的多個方面。盡管二者都維持線粒體完整性，Hsp90-Cdc37和自吞噬之間的關(guān)系一直沒有搞清楚。Ulk1，酵母菌Atg1的哺乳類同系物之一，是自吞噬所需的絲氨酸- 蘇氨酸激酶。美國科學家的最新研究顯示Ulk1 和Hsp90-Cdc37之間的相互作用穩(wěn)定和激活Ulk1 , 這又是磷酸化Atg13和從Ulk1釋放Atg13，以及招募Atg13到受損傷的線粒體所必須。Hsp90-Cdc37, Ulk1, 以及Atg13磷酸化都是有效清除線粒體所必須的。 這些發(fā)現(xiàn)建立了一種直接的方法整合Ulk1- 和 Atg13-指導的自吞噬和Hsp90 與Cdc37協(xié)調(diào)的應激反應。

【點評】
該研究可以幫助我們認識線粒體的自吞噬機制。

【參考論文】
Molecular Cell, 2011; 43 (4): 572 DOI: 10.1016/j.molcel.2011.06.018
Hsp90-Cdc37 Chaperone Complex Regulates Ulk1- and Atg13-Mediated Mitophagy
Joung Hyuck Joo, Frank C. Dorsey, Aashish Joshi, et al.
Autophagy, the primary recycling pathway of cells, plays a critical role in mitochondrial quality control under normal growth conditions and in the response to cellular stress. The Hsp90-Cdc37 chaperone complex coordinately regulates the activity of select kinases to orchestrate many facets of the stress response. Although both maintain mitochondrial integrity, the relationship between Hsp90-Cdc37 and autophagy has not been well characterized. Ulk1, one of the mammalian homologs of yeast Atg1, is a serine-threonine kinase required for mitophagy. Here we show that the interaction between Ulk1 and Hsp90-Cdc37 stabilizes and activates Ulk1, which in turn is required for the phosphorylation and release of Atg13 from Ulk1, and for the recruitment of Atg13 to damaged mitochondria. Hsp90-Cdc37, Ulk1, and Atg13 phosphorylation are all required for efficient mitochondrial clearance. These findings establish a direct pathway that integrates Ulk1- and Atg13-directed mitophagy with the stress response coordinated by Hsp90 and Cdc37.