Structure of the Sec23p/24p and Sec13p/31p complexes of COPII

COPII-coated vesicles carry proteins from the endoplasmic reticulum to the Golgi complex. This vesicular transport can be reconstituted by using three cytosolic components containing five proteins: the small GTPase Sar1p, the Sec23p/24p complex, and the Sec13p/Sec31p complex. We have used a combination of biochemistry and electron microscopy to investigate the molecular organization and structure of Sec23p/24p and Sec13p/31p complexes. The three-dimensional reconstruction of Sec23p/24p reveals that it has a bone-shaped structure, (17 nm in length), composed of two similar globular domains, one corresponding to Sec23p and the other to Sec24p. Sec13p/31p is a heterotetramer composed of two copies of Sec13p and two copies of Sec31p. It has an elongated shape, is 28-30 nm in length, and contains five consecutive globular domains linked by relatively flexible joints. Putting together the architecture of these Sec complexes with the interactions between their subunits and the appearance of the coat in COPII-coated vesicles, we present a model for COPII coat organization.     

Chromosome 17p and p53 changes in lymphoma

The clinical course of lymphoma patients in whom rearrangements or deletions of the short arm of chromosome 17 (17p) were evident by cytogenetics was rapidly progressive with a short survival. The gene for the protein designated p53 resides in 17p. We studied four lymphoma cell lines derived from human tumours, and 25 tumour samples of patients with lymphomas, for any evidence of p53 genomic changes by Southern blot technique. The four cell lines and four of the 25 tumour samples showed numerical changes of chromosome 17 or structural abnormalities of 17p (translocations or deletions). Allelic loss of the p53 gene was found in two of the four cell lines, and one of these in addition showed a rearrangement of the 3' end of the gene. Of the four tumours known to have chromosome 17 abnormality, one specimen showed allelic loss of the p53 gene. None of the remaining tumour samples showed any significant change. These studies suggest that acquisition of changes in the short arm of chromosome 17, which may be interrelated with the p53 gene, may carry a poor prognosis in patients with non-Hodgkin's lymphoma.     

Contribution of p53, p63, and p73 to the developmental diseases and cancer

Tumor suppressor TP53 gene is one of the most mutated genes in human genome. Inactivating somatic mutations and disruption of p53 protein have been described in almost all human malignancies. Its inactivation by germline mutation leads to the rare but severe familial precancerosis termed Li-Fraumeni syndrome. This syndrome is characterized by the early onset of different types of cancers including soft-tissue sarcomas, breast and brain cancers, leukemias, lung, laryngeal cancers, and adrenocortical carcinomas. The key role of p53 in tumor suppression has been confirmed in animal models as well. The p53 -knock-out and knock-in animals were born alive but were tumor prone. In the late nineties, two genes with high homology with TP53 were discovered, TP73 and TP63, respectively. Animal models showed that p73 is an important player in neurogenesis, sensory pathways and homeostatic control. The p63 is critical for the development of stratified epithelial tissues such as epidermis, breast, and prostate. Despite the structural similarities with p53, the function of these proteins in tumorigenesis is controversial. On one hand, there are evidences that both, p63 and p73-deficient animals are not tumor prone; on the other hand, there is evidence that such animals develop tumors later during their life. Unlike in TP53 gene, mutations in TP63 and TP73 genes are rare, however, germline mutations in TP63 are linked to the human developmental diseases. In this minireview, we describe the contribution of the p53, p63, and p73 to human pathology with emphasis on their different roles in development and tumorigenesis.     

Immunohistochemical Expression of p16, p53, and p63 in Colorectal Adenomas and Adenocarcinomas

Purpose The aim of this study was to investigate the immunohistochemical expression of p16, p53, and p63 proteins according to some pathologic parameters related to colorectal adenomas and adenocarcinomas such as grade of dysplasia and histologic type. Methods Immunohistochemistry with the antibodies p16, p53, and p63 was performed in tubular, tubular-villous, and villous adenomas (n = 30) and in well, moderately, and poorly differentiated adenocarcinomas (n = 30). The p63-positive cases were submitted to double immunolabeling with the cytokeratin 5 (CK5). Results The p16 and p53 labelings were observed in some adenomas and adenocarcinomas but without any association with p63 expression, histologic type, or grade of differentiation of the neoplasm. P63 expression was found mainly in the villous adenomas and in the poorly differentiated adenocarcinomas. The poorly differentiated adenocarcinomas also exhibited coexpression of CK5 and p63. Conclusions Despite both p16 and p53 having been detected in colorectal neoplasms, they were not related to the different histologic variables nor to the expression of p63. However, p63 expression was closely associated with villous adenomas and poorly differentiated adenocarcinomas. Thus, p63 may represent a marker of poor differentiation in colorectal neoplasms. The coexpression of p63 and CK5 observed in this study could be related to divergent differentiation during the development of colorectal cancer, although further studies are warranted to refine the understanding of this process.     

Immunodominant epitopes of HIV-1 p17 and p24.

Immunodominant antibody-binding sites were mapped using overlapping synthetic peptides of the structural proteins p17 and p24 of human immunodeficiency virus type 1 (HIV-1). Using sera from HIV-1-infected individuals at a variety of disease states, three major epitopes were identified within p17 and one within p24. Antibodies which recognized these epitopes were present in all risk groups throughout all stages of HIV infection, regardless of the presence of high levels of serum p24 antigen.     

p21和p27基因多态性与妇科肿瘤的相关性研究

目的探讨p21和p27基因多态性与妇科肿瘤遗传易感性的关系。方法采用聚合酶链反应—限制性片段长度多态性方法,分析100例妇科肿瘤患者和95例健康对照者的p21基因3′非翻译区（3′UTR）和p27基因第109密码子多态性位点的基因型。结果妇科肿瘤患者p21基因突变型TT频率为26.00%,对照者为16.84%,两者相比,P〈0.01;年龄〈46岁组肿瘤患者的p21基因突变型（CT＋TT）频率为86.84%,≥46岁组为59.52%,两组相比,P〈0.01;中低分化组妇科肿瘤患者的突变型CT和TT基因型频率为76.47%,高分化组为46.67%,两组相比,P〈0.05;妇科肿瘤患者与对照者的p27基因型总体分布及V和G等位基因频率相比,P均〈0.01。结论p21基因3′UTR多态性和p27基因V109G多态性与妇科肿瘤的遗传易感性有关。     

p73和p51基因在结直肠癌中的表达和意义

背景：p53基因是一种肿瘤抑制基因，其家族成员p73和p51在结构上与p53具有高度同源性，影响细胞转录和凋亡的功能与p53相似。目的：研究p73和p51基因在结直肠癌中的表达及其与细胞凋亡和肿瘤临床病理特征的关系，探讨两者在结直肠癌发生、发展中的可能作用。方法：以逆转录聚合酶链反应（RT—PCR）检测60例结直肠癌组织和相应癌旁组织中p73、p51mRNA表达，以原位末端标记（TUNEL）法检测细胞凋亡。结果：结直肠癌组织p73、p51AmRNA表达阳性率显著高于相应癌旁组织（p73：71．7％对5．0％，P〈0．01：p51A：46．7％对11．7％，P〈0．01）：p51B mRNA在结直肠癌组织与相应癌旁组织中的相对表达量无明显差异（0．7318±0．3628对0．6836±0．3516，P〉0．05）。p73、p51A mRNA表达阳性者肿瘤细胞凋亡指数分别显著低于p73、p51A mRNA表达阴性者（p73：3．2％±2．5％对5．5％±2．8％．P=0．003；p51A：2．6％±2．3％对4．9％±2．7％，P=0．001）。p73mRNA表达与结直肠癌的分化程度、TNM分期和淋巴结转移相关（P〈0．05），p51A mRNA表达仅与淋巴结转移相关（P〈0．05）。结论：结直肠癌中p73、p51A基因表达上调，两者可能通过抑制肿瘤细胞凋亡而参与了结直肠癌的发生、发展。p73过表达可能与结直肠癌预后不良有关。     

Distinct roles of p42/p44ERK and p38 MAPK in oxidant-induced AP-1 activation and cardiomyocyte hypertrophy

Cardiac hypertrophy is an adaptive response to a number of heart diseases including myocardial infarction. Although it can be compensatory at first, sustained hypertrophy is often a transition to heart failure. We have found that cardiomyocytes in culture can survive mild doses of H₂O₂ but develop hypertrophy involving activation of p70 S6 kinase 1 (p70S6K1). Here, the role of p42/p44^ERK and p38 MAPK in oxidant-induced hypertrophy is tested. H₂O₂-induced phosphorylation (activation) of p42/p44^ERK and p38 within 10 min of 200 μM H₂O₂ exposure. Although p42/p44^ERK remained highly phosphorylated from 60 to 120 min, the level of p38 phosphorylation reached highest at 60 min and started to decline at 90 min. Inhibiting ERKs with PD98059 attenuated H₂O₂-induced AP-1 activation but did not affect H₂O₂-induced p70S6k1 activation or cardiomyocyte enlargement as measured by increases in cell volume and protein content. In contrast, the p38 inhibitor SB202190 has not inhibitory effect on AP-1 activation but partially prevented H₂O₂ from inducing p70S6K1 activation and cell enlargement. These data suggest that while p42/p44^ERK participates in gene expression associated with hypertrophy, p38 may regulate cell size increase by p70S6K1 activation.     

Expressions of p16 and p27 in urothelial carcinoma and their prognostic value

Expressions of human p16 and p27 were tested for correlations with clinicopathologic features of urothelial carcinoma (UC). Tissue microarrays (TMA) constructed from paraffin-embedded specimens from 78 patients with UC were analyzed by immunohistochemical staining. In 49 of the 78 tumors (63%), high p16 expression was associated with absence of tumor invasiveness and low-grade carcinoma (p = 0.003 and p = 0.046, respectively). The p27 expression was high in 33 of the 78 tumors (42%) and showed a significant negative association with invasiveness, carcinoma grade, and tumor size (p = 0.016, p = 0.046, and p = 0.014, respectively). Kaplan–Meier analysis indicated that patients with high p27 levels had longer than average overall survival (p = 0.021). This study demonstrates that p16 and p27 are prognostic indicators of tumor stage and grade in UC and that they provide clinicians with the ancillary information needed for selecting suitable therapeutic strategies.     

Polymorphism of HIV type 1 gag p7/p1 and p1/p6 cleavage sites: clinical significance and implications for resistance to protease inhibitors

Amino acid substitutions at HIV-1 Gag p7/p1 and p1/p6 cleavage sites may be selected under antiretroviral pressure or represent natural polymorphisms. Whether changes are associated with specific protease (PR) mutation patterns and different clinical evolution has not been investigated. p7/p1 and p1/p6 cleavage site sequences from sera from 110 patients infected with HIV-1 were compared by regression analysis, using clinical, laboratory, and sequence variables, and the evolution of CD4(+) cell counts and viral load over time. Sixteen of 35 (46%) individuals naive to PR inhibitors (PIs), and 49 of 75 (65%) receiving PI-containing regimens had a p7/p1 and/or p1/p6 cleavage site polymorphism (p = 0.06). A431V and/or L449F were present exclusively among individuals failing PI treatment (17 of 75 [23%] and 3 of 75 [3%], respectively). There was a significant association between A431V and PR M46I,L (OR 13.7; 95% CI 4.2-44.3) and V82A,F,T (OR 8.8; 95% CI 2.7-27.8). Natural polymorphism P453L was strongly associated with the selection of PR I84V (OR 49.5; 95% CI 12-212) and selected against V82 mutation (OR 0.15; 95% CI 0.02-1. 2). After a median followup of 15 months, no polymorphism was associated with parameters of disease progression among individuals failing treatment. Only a limited set of amino acid substitutions can be tolerated at p7/p1 and p1/p6 cleavage sites. A431V is selected in association with specific PR inhibitor mutations. Natural polymorphism P453L might direct the PR resistance pathway through I84V instead of V82 mutation. No short-term clinical impact of cleavage site substitutions was documented.     

人原发性肝癌细胞株受照射后凋亡与癌基因表达

目的 探讨人原发性肝癌细胞株受照射后凋亡与ｂｃｌ－２、ｐ５３基因表达产物关系。方法 选择人原发性肝癌细胞株ＱＧＹ,１８０ＫＶＸ线照射,流式细胞仪技术定量测定凋亡发生率,单克隆抗体免疫化法测定受照射后ｂｃｌ－２、ｐ５３表达产物,Ｓｏｎｙ Ｍｉａｓ－３００ Ｓｐａｔｏ图象分析仪分析结果。结果 ＱＧＹ－７７３０细胞株自发凋亡率为４．７９％,随照射后时间延长及照射剂量增加凋亡发生率增加。Ｂｃｌ－１、ｐ５３     

食管内反流物成分与p53、细胞周期素D1、p21、p16表达的相关性研究

目的 研究胃及十二指肠液食管反流对食管内抑癌基因、癌基因表达的影响及与黏膜损伤的关系。方法 制作单纯胃食管反流（G组）、单纯十二指肠食管反流（D组）、十二指肠胃混合食管反流（DG组）及无反流对照组（C组）动物模型,用免疫组化法（SABC）检测各组不同时期食管上皮P53、细胞周期素D1（Cyclin D1）、p21、p16等基因的表达。结果 反流组食管组织中p53、CyclinD1基因表达均显著高于C组,并随病程延长而明显增强,D组表达又强于G组;各组不同时期p16表达无明显差异;p21表达在D组、DG组较C组为低,且与p53蛋白表达呈负相关。结论 食管内胃及十二指肠反流物均可改变食管上皮p53、Cyclin、p21基因的表达,十二指肠内容物的作用更明显。但反流对p16基因的表达影响不大。p53、CyclinD1、p21等癌基因或抑癌基因的表达改变可能参与反流性食管炎及其并发症的发生。