自噬研究新进展

自噬是广泛存在于真核细胞内的一种溶酶体依赖性降解途径,是细胞进行自我保护的一种重要机制,在维持细胞存活、更新、物质再利用和内环境稳定中起着重要作用.近年来,针对自噬的研究日益深入,本文对新提出来的受损自噬(frustrated au-tophagy)概念及意义、自噬与凋亡间分子联系的新发现,以及雷帕霉素靶蛋白(mamalian target of mpamycin,mTOR)自噬调节的新动态概述如下.     

α粒子辐射对ROS介导src激酶活性和自噬的影响

目的 通过检测人胚肾上皮细胞HEK293受不同剂量α粒子照射后,src激酶活性和细胞自噬系统的变化,探讨调控细胞自噬对高剂量辐射诱导细胞死亡的影响.方法 将人胚肾上皮细胞HEK293分为3组:0 cGy(对照)组、241Am α粒子照射低剂量(10 cGy)组和高剂量(300 cGy)组.应用免疫印迹实验检测细胞内源性蛋白LC3Ⅰ/Ⅱ和src激酶的变化;分子探针检测细胞内活性氧(ROS)水平;用ROS淬灭剂DMSO预处理照射细胞,并用免疫印迹法检测照射后src激酶的变化;使用自噬诱导剂雷帕霉素预处理照射细胞,以PI染色流式细胞术测定细胞死亡率.结果 与0 cGy相比,10 cGy α射线照射后LC3 Ⅰ/Ⅱ比例降低(=4.07,P＜0.05),胞质内具有绿色荧光点状GFP-LC3的细胞比例升高(t=12.29,P＜0.05),自噬被诱导;而300 cGy照射后,LC3Ⅰ/Ⅱ比例升高(t=2.93,P＜0.05),胞质内GFP-LC3形态无明显变化,自噬被抑制.与0 cGy相比,10和300 cGy照射后4h均能提升细胞内ROS水平(t=17.93、22.88,P＜0.05),且300 cGy比10 cGy照射诱发的ROS更多(t=15.76、22.66、14.22,P＜0.05).与0 cGy相比,10 cGy照射使src激酶419位酪氨酸磷酸化水平升高(t=5.66,P＜0.05),而300 cGy照射则降低其磷酸化水平(=4.67,P＜0.05).DMSO能够部分逆转高低剂量照射对src激酶活性的影响.辐照前以自噬诱导剂雷帕霉素处理细胞则能降低300 cGy照射诱发的细胞死亡率(t=12.14,P＜0.05).结论 高低剂量α粒子分别抑制和激活src激酶以及细胞自噬,ROS参与介导辐照对src激酶活性及自噬系统的影响.对自噬系统的干预能够降低细胞的辐射敏感性.     

细胞自噬与血脑屏障的关系研究进展

自噬对细胞具有一定的保护作用,但过度自噬则会导致细胞程序性死亡,称为Ⅱ型程序性细胞死亡。血脑屏障(BBB)在大脑与外周循环之间起保护作用,有助于分子和离子的流入和流出,以维持中枢神经系统的稳态。大量研究表明,细胞自噬在BBB功能中发挥着重要作用,一方面可对BBB的完整性起到损伤或保护作用,另一方面可影响药物、病原体等物质穿越BBB。因此,通过靶向自噬机制中的特定调节分子来调节自噬水平可能影响BBB的功能,进而影响中枢神经系统疾病的发生和发展。本文对细胞自噬与BBB之间关系的研究进展进行综述,以期为预防和治疗BBB损伤相关的疾病提供新思路。     

光动力治疗与细胞自噬的研究进展

细胞自噬是真核生物中一种发现不久的普遍存在的生理现象,是涉及细胞自我消化的一系列生化过程。光动力治疗（photodynamic therapy,PDT）中,选择性聚集在快速增殖细胞（如肿瘤细胞）中的光敏剂分子经一定波长激光照射,产生有细胞毒作用的单态氧或氧自由基,靶向性地杀伤肿瘤细胞,引起肿瘤细胞死亡。PDT作用过程能够诱发一些细胞器如内质网、线粒体、细胞膜和溶酶体的损害,进而引起细胞凋亡和自噬的发生。对于一些接受低水平剂量的光动力作用细胞,其发生的自噬被认为与提高细胞在应激环境下的生存有着密切联系。然而,当凋亡受到抑制或是自噬水平无限制的持续上调时,自噬就成为了细胞死亡的一种途径。目前很多相关的实验技术已运用来检测细胞自噬的特征,本文就针对光动力治疗后引起自噬的一些相关问题做一详细综述。     

自噬在非小细胞肺癌治疗中的研究进展

非小细胞肺癌（non-small-cell lung cancer,NSCLC）占所有肺癌的85%,是全球癌症相关死亡的主要原因,目前的治疗方法主要包括手术治疗、放疗、化疗、生物治疗等。然而化疗的缓解率不高且不良反应明显,靶向治疗只对特定人群有效,且容易出现耐药问题,因此,需要开发新的、更有效的NSCLC治疗方法。细胞自噬在NSCLC的病理生理过程中起着重要作用,作者通过分析自噬在肿瘤中发挥的双刃剑作用,对自噬相关基因进行研究,综述自噬在铂类耐药、表皮生长因子受体酪氨酸激酶抑制剂耐药及与免疫检查点抑制剂的联合应用中起到的重要作用,分析自噬在NSCLC治疗的应用前景,为NSCLC的新疗法的发展提供一些参考。     

细胞自噬在病原体感染过程中的作用研究进展

细胞自噬是一种通过降解蛋白质和细胞器维持细胞内平衡的细胞机制。细胞自噬具有很多重要的生理功能,包括清除病原体的感染。但是由于细胞自噬在进化过程中具有高度的保守性,某些病原体通过进化,具有逃避细胞自噬的能力,甚至利用细胞自噬为病原体复制和发育提供有利条件。本文综述了细胞自噬与病原体相互作用的研究进展。     

自噬在肿瘤细胞死亡中的研究进展

自噬是细胞将自身的胞质蛋白和细胞器以形成自噬体的形式由溶酶体降解的过程,其既是细胞保守的自我防御机制,又是一种程序性细胞死T亡机制。诸多研究表明,自噬不仪参与机体多项生理功能的发挥,而且其功能的失调还与神经变性性疾病、自身免疫性疾病、肿瘤等多种疾病相关,但具体机制尚不明确,仍需进一步深入研究探讨。由此,本文综述了自噬的细胞学调控,以及其对细胞程序性死亡的影响和自噬诱导的细胞死亡在肿瘤发生发展中的作用机制,旨在为细胞自噬在肿瘤发生发展中的作用研究以及肿瘤治疗靶点的开发提供思路与线索。     

自噬介导运动改善肥胖症脂肪组织炎症状态研究进展

肥胖已成为21世纪影响全球人类健康的主要危险因素,而其本质之一即为脂肪组织发生的慢性炎症状态,继而释放大量炎症介质入血引起肥胖相关代谢疾病的发生。运动与能量限制等手段可有效控制肥胖,且近年来关于运动减肥机制的分子生物学证据不断涌现。自噬过程作为细胞内保守的亚细胞事件,其在运动改善肥胖症脂肪组织炎症状态中发挥重要作用。本文对国内外关于肥胖过程中脂肪细胞自噬的变化及运动对肥胖症脂肪细胞自噬影响的研究加以综述,并且聚焦于自噬介导运动调控肥胖症脂肪组织炎症状态的变化,为运动减肥的分子机制提供理论依据。     

p53凋亡刺激蛋白2在HepG2215细胞中通过抑制自噬来发挥抗乙型肝炎病毒的作用

目的 研究p53凋亡刺激蛋白2(apoptosis stimulating protein 2 of p53,ASPP2)对乙型肝炎表面抗原（hepatitis B surface antigen,HBsAg）和乙型肝炎E抗原（hepatitis Be antigen,HBeAg）表达的影响。方法 HepG2.215细胞用3-甲基腺嘌呤处理来抑制自噬,或用人ASPP2重组腺病毒感染来诱导ASPP2过表达,或转染GFP-LC3质粒后观察绿色LC3-Ⅱ颗粒（自噬标志物）的变化。酶联免疫吸附测定检测培养上清和胞内HBsAg和HBeAg的水平、免疫荧光检测LC3-Ⅱ颗粒的水平、免疫印记检测自噬相关蛋白的水平、免疫沉淀检测ASPP2与自噬相关蛋白的结合。结果 ASPP2过表达明显下调了绿色LC3-Ⅱ颗粒的水平和LC3-Ⅱ/Ⅰ比例、以及明显上调p62的水平,说明ASPP2过表达可抑制HepG2.215细胞的自噬。但是ASPP2并非通过抑制Atg5、Atg14和Beclin-1等自噬相关基因的表达来抑制自噬,而是通过与Atg14结合来抑制Atg14与Beclin-1的结合,阻断自噬体膜的形成,从而抑制自噬。抑制自噬和ASPP2过表达均导致培养上清和细胞内的HBsAg和HBeAg水平明显下调,表明在Hep2.215中,ASPP2通过抑制自噬来抑制HBsAg和HBeAg的产生。结论 ASPP2通过抑制自噬的作用具有抗乙型肝炎病毒感染的潜力。     

p53在细胞自噬发生中的双重调节作用

细胞自噬是一种进化上比较保守的分解代谢过程,不仅参与细胞的许多生理过程,而且与多种病理状态包括癌症相关,因此其调节机制也相当精确且复杂.越来越多的研究表明,抑癌基因p53在细胞自噬反应发生中具有双重调节作用,这主要取决于其亚细胞定位.该文就p53对自噬反应的正、负调节作用及机制作一综述.     

Physiologic and pathologic calcifications and ossifications in the face and neck

The aim was to give a systematic presentation of physiologic and pathologic calcifications and ossifications in the face and neck with a special emphasis on clinical relevance. In a sometimes subacute setting one should recognize specific calcifications which often lead to important diagnoses such as fungal sinusitis or sclerosing labyrinthitis. In a more chronic situation intraocular calcifications in small children are pathognomonic for retinoblastoma. Juxtatumoral sclerosis of the laryngeal cartilage in laryngopharyngeal carcinoma is usually caused by tumor infiltration of the cartilage resulting in a higher tumor stage and, this way, has a major impact on the therapeutical strategy. Calcified lymph nodes are mainly unspecific but can be the result of tuberculosis or metastases of thyroid cancer. Cross-sectional imaging methods, most of all computed tomography, are ideally suited to reveal head and neck calcifications and ossifications, especially those which are clinically relevant.     

Head and neck infection and inflammation

This article discusses the imaging manifestations of infectious and inflammatory conditions of the head and neck. Special attention is paid to the sites, routes of spread, and complications of neck infections. Because the clinical signs and symptoms and the complications of these conditions are often determined by the precise anatomic site involved, anatomic considerations are stressed. Familiarity with the fascial layers, spaces of the neck, and the contents of each space is helpful for this discussion. The fascial layers of the neck are important barriers to infection, and once infection is established, the fascial layers play a part in directing its spread.     

Staging and surgical management of pancreatic and biliary cancer and inflammation

Management of benign and malignant diseases of the pancreas, liver, and biliary tract has made remarkable progress in the last two decades. Advances in minimally invasive surgery, interventional radiology, and diagnostic and therapeutic endoscopy have changed the treatment of common diseases such as cholelithiasis and more serious diseases such as pancreatic adenocarcinoma. Advances in biliary tract and pancreatic surgery have paralleled the advances in ultrasonographic imaging, CT, and MR imaging. This article outlines the surgeon's perspective on radiologic imaging and preoperative staging of benign and malignant biliary and pancreatic disease.     

The thyroid and parathyroid glands. CT and MR imaging and correlation with pathology and clinical findings

Thyroid imaging approach is based on the preliminary clinical evaluation. Lesions that are smaller than 2 cm should be assessed with US, which is capable of discriminating masses as small as 2 mm and distinguishing solid from cystic nodules. US-guided FNAB provides tissue for cytologic examination of thyroid nodules. CT and MR imaging are indicated for larger tumors (greater than 3 cm diameter) that extend outside the gland to adjoining structures, including the mediastinum, and retropharyngeal region. Metastatic lymph nodes in the neck and invasion of the aerodigestive tract are also in the realm of CT and MR imaging. Thyroid nodules are categorized on scintigraphy as hot or cold nodules. Hot nodules are rarely malignant, whereas cold nodules have an incidence of 10% to 20% of malignancy. Calcifications (amorphous, globular, nodular, and linear) occur in adenomas and carcinomas and have no differential diagnostic features except for psammomatous calcifications, which are a pathognomonic finding in papillary carcinomas and a small percentage of medullary carcinomas. Papillary carcinoma is the most common malignant tumor (80%) followed by follicular (20% to 25%); medullary (5%); undifferentiated; anaplastic carcinomas (< 5%); lymphoma (5%); and metastases. Lymph node metastases are common in papillary carcinoma, 50% at presentation, and less common in follicular carcinomas. The metastatic nodes in papillary carcinoma may enhance markedly (hypervascular); show increased signal intensity on T1-weighted images (increased thyroglobulin content or hemorrhage); and reveal punctate calcifications. Localized invasion of the larynx, trachea, and esophagus occurs predominantly in papillary and follicular carcinomas; the incidence is less than 5%. Ectopic thyroid tissue may be encountered in the tongue (foramen cecum); along the midline between posterior tongue and isthmus of thyroid gland; lateral neck; mediastinum; and oral cavity. Goiter and malignant tumors, notably papillary carcinoma, may develop in ectopic thyroid tissue. Carcinomas may also arise in thyroglossal duct cysts, which develop from duct remnants between the foramen cecum and thyroid isthmus. Infectious disease of the thyroid gland is not common and the CT and MR imaging findings are similar as described under neck infection. Other types of inflammatory disorders including Hashimoto's thyroiditis, granulomatous thyroiditis, and Riedel's struma display no specific imaging features. Imaging studies may, however, be indicated to confirm a suspected clinical diagnosis and assess compromise of the airway (Riedel's struma). HPT is a clinical diagnosis in which hypercalcemia is the most important finding. Parathyroid hyperplasia, adenoma, and carcinoma represent underlying lesions. To relieve the patient's symptoms surgical extirpation is indicated. The surgical success rate without imaging is 95%. The indications for imaging studies vary but it is generally agreed that reoperation after a previous failed surgical attempt and suspicion of an ectopic parathyroid adenoma should be investigated by imaging. These consist of US, nuclear medicine studies, CT and MR imaging. US and technetium sestamibi scanning have the highest accuracy rate for localizing an adenomatous gland at and near the thyroid gland. Ectopic adenomas, particularly if they are located in the mediastinum, are preferrably investigated with CT and MR imaging with gadolinium and fat suppression. Carcinomas and parathyroid cysts are optimally evaluated by CT and MR imaging. On MR imaging adenomas are low in signal intensity on T1-weighted images, high in signal intensity on T2-weighted images, and enhance post introduction of gadolinium.     

幽门螺杆菌分泌与重组表达的VacA蛋白的分离纯化及其致细胞空泡效应与凋亡的对比研究

目的：分离纯化幽门螺杆菌分泌和重组表达的细胞空泡毒素抗原（ VacA）蛋白,并评价其致细胞空泡效应及致细胞凋亡效应。方法分别从幽门螺杆菌ATCC26695菌株培养上清和重组表达VacA蛋白的pQE30-VacA-E．coliM15基因工程菌中分离纯化VacA蛋白,经酸化后,以不同终浓度（5,10 ng／ml）分别与人胃腺癌AGS细胞共孵24 h,观察致空泡效应,并通过流式细胞术检测细胞凋亡。结果成功分离纯化出幽门螺杆菌分泌和重组表达的VacA蛋白;幽门螺杆菌分泌的VacA蛋白能显著引起AGS细胞的空泡样改变及凋亡（P＜0．01）,而重组表达的VacA蛋白致细胞空泡样改变及凋亡不显著（ P＞0．05）。结论幽门螺杆菌分泌的VacA蛋白有良好的空泡毒性及致凋亡效应,而重组表达的VacA蛋白无致空泡及凋亡效应,幽门螺杆菌分泌的VacA蛋白可用于VacA作用机制的研究。