C型凝集素糖基识别结构域的结构功能研究进展

蛋白质与蛋白质糖链的相互作用在固有免疫和适应免疫中发挥重要作用,涉及病原微生物的识别和免疫细胞之间的相互作用,参与这种作用的分子称为凝集素分子(lectins),其中依赖钙离子的(C-type)凝集素家族(lectin family)为其主要成员.

甘露糖结合凝集素研究进展

甘露糖结合凝集素(mannose-binding lectin,MBL)是一种由肝脏合成的c型凝集素.MBL通过结合病原微生物表面的片露糖等糖基配体而直接介导巨噬细胞调理吞噬作用和/或通过凝集素途径激活补体,在机体的天然免疫防御中发挥重要作用.

Aim: To investigate glycoconjugate changes on the cell surface of proliferative lesions and neoplasms of mice lungs at various stages of tumorigenesis, the relation between progressive development of mouse pulmonary tumors and expression of cell surface saccharide. Materials and methods: Thirty - one male A/J strain mice at 5 weeks of age were treated intraperitoneally with a single injection of 20 - methylcholanthrene (20 - MC), 292 pulmonary lesions including 31 hyperplasias, 145 alveolar adenomas, 61 papillary adenomas, 55 papillary adenocarcinomas and their combined type were obtained. The binding affinities of cells in normal respiratory epithelia and in proliferative lesions to four peroxidases - conjugated lectins, Maclura pomifera agglutinin (MPA), Arachis hypogea agglutinin (PNA), Ricinus communis agglutinin (RCA), and wheat germ agglutinin (WGA) were examined. Results: Cells of hyperplasia and alveolar adenoma showed fairly strong affinity to all the four lectins. However, part of papillary adenoma cells and greater part of papillary adenocarcinoma cells lost their binding affinity to MPA, PNA, and RCA, but not to WGA. The bindings of MPA, PNA and RNA were detected predominently on the luminal surfaces of benign tumors but not on the luminal surfaces of malignant tumors. WGA might bind to varied types of benign and malignant tumors. Pretreated with neuraminidase, the lesions enhanced the staining intensity for the four lectins, the binding sites of WGA to malignant tumor cells were numerous. A distinct difference in lectin binding affinity between hyperplasia / alveolar adenoma/papillary adenoma and papillary adenocarcinoma was clearly shown( x2 = 46.89, P ＜ 0.01, x2 = 36.77, P ＜ 0.01 and x2 = 52.87, P ＜ 0.01 ) in this experiment. The complex glycoconjugates on the cell surface of malignant and benign lesions during the development of pulmonary tumor were changed,malignant tumor cells differed from the surface of benign tumor cells, the levels of total sialic acid were higher in malignant tumor cells than in benign lesions. Conclusions: The expressions of glycoconjugates on cell surface by lectins may assist differential diagnosis of the malignant and benign lung lesions.

AIM To study the agglutination pattern of Helicobacter pylori coccoid and spiral forms.METHODS Assays of agglutination and agglutination inhibition were applied using fifteen commercial lectins. RESULTS Strong agglutination was observed with mannose-specific Concanavalin A (Con A ),fucose-specific Tetragonolobus purpureas ( Lotus A ) and N-acetyl glucosamine-specific Triticum vulgaris (WGA) lectins. Mannose and fucose specific lectins were reactive with all strains of H. pylori coccoids as compared to the spirals. Specific carbohydrates, glycoproteins and mucin were shown to inhibit H. pylori lectin-agglutination reactions. Pre-treatment of the bacterial cells with formalin and sulphuric acid did not alter the agglutination patterns with lectins. However, sodium periodate treatment of bacterial cells were shown to inhibit agglutination reaction with Con A, Lotus A and WGA lectins. On the contrary, enzymatic treatment of coccoids and spirals did not show marked inhibition of H. pylori-lectin agglutination. Interestingly, heating of H.pylori cells at 60℃ for 1 hour was shown to augment the agglutination with all of the lectins tested. CONCLUSION The considerable differences in lectin agglutination patterns seen among the two differentiated forms of H. pylori might be attributable to the structural changes during theevents of morphological transformation,resulting in exposing or masking some of the sugar residues on the cell surface. Possibility of various sugar residues on the cell wall of the coccoids may allow them to bind to different carbohydrate receptors on gastric mucus and epithelial cells. The coccoids with adherence characteristics like the spirals could aid in the pathogenic process of Helicobacter infection.This may probably lead to different clinical outcome of H. pylori associated gastroduodenal disease.

妊娠期糖尿病孕妇血清甘露糖结合凝集素水平和胰岛素抵抗的关系

妊娠期糖尿病(gestational diabetes mellitus,GDM)病因尚不明确.胰岛素抵抗(insulin resistance,IR)和胰岛β细胞分泌降低被认为在其发病机制中起重要作用[1].近年来,2型糖尿病发病机理的炎症学说备受关注,许多学者认为GDM也是一种自然免疫和炎症性疾病[2].甘露糖结合凝集素(mannose-binding lectin,MBL)是由肝和胰岛分泌的一种急性期反应蛋白.

MASP-2与相关性疾病的研究进展

近年来,许多抗感染和抗肿瘤的天然免疫分子不断被发现.其中模式识别受体-病原体相关分子模式(pattern recognition receptor - pathogen associated molecule pattern, PRR-PAMP)引起国内外学者的高度重视.人甘露糖结合凝集素(MBL)相关丝氨酸蛋白酶-2(Mannan-binding lectin associated serine protease 2,MASP-2)属于丝氨酸蛋白酶家族,MASP-2是天然免疫系统中的重要组分,在补体激活的凝集素途径中发挥至关重要的作用.

Roundup Ready大豆中Lectin、CaMV 35S、NOS和CP4 EPSPS基因的提取与RT-PCR定性范围研究

[目的]研究Roundup Ready大豆的Lecfin、CaMV 35S、NOS和CP4 EPSPS等被检测基因的RT-PCR定性范围.[方法]用CrAB法提取DNA,对Lectin、CaMV 35S、NOS和CP4 EPSPS等被检测基因的检测条件进行了优化,确定了被检测基因在相同RT-PCR条件下的定性范围.[结果]研究发现.不同被检测基因在相同RTPCR条件下的浓度检出范围不同.Lectin为0.05～792 mg/L.CaMV 35S为0.25～792 mg/L.NOS为0.25～396mg/L,CP4 EPSPS为0.05～1980mg/L,共同的方法检出限LOD为5 ng.体系浓度范围为0.25-396 mg/L.[结论]确定了Roundup Ready大豆被检测基因的定性范围和检出限,可应用于大豆中相关基因的检测.