The prothrombin 20209 C→T mutation in Jewish-Moroccan Caucasians: molecular analysis of gain-of-function of 3'' end processing

BACKGROUND: Mutations of the 3' end mRNA-processing signal of the prothrombin (F2) gene have been reported to cause elevated F2 plasma concentrations, thrombosis, and complications of pregnancy. Whereas the common F2 20210*A mutation is almost exclusively found in Caucasians, the F2 20209*T mutation has been reported in Afro-Americans and Afro-Caribbeans only. PATIENTS AND METHODS: Using LightCycler technology, three unrelated Jewish-Moroccan patients tested for obstetric complications were found to be carriers of the F2 20209*T allele. A detailed molecular analysis was performed to identify the functional impact of this mutation. RESULTS: We report three unrelated women of Jewish-Moroccan origin with a F2 20209*T mutation and fetal loss or infertility. The functional analysis revealed that the F2 20209*T mutation stimulates 3' end processing and up-regulates prothrombin protein expression as assessed by a highly sensitive luminescence-based reporter system. CONCLUSIONS: This is the first report of 20209*T in Caucasians, and functional analysis demonstrates that F2 20209*T falls into a general category of mutations of the F2 gene, which may possibly contribute to thrombophilia and complications of pregnancy by interfering with a tightly balanced architecture of non-canonical F2 3' end formation signals.     

Aging defined by a chronologic-replicative protein network in Saccharomyces cerevisiae: An interactome analysis

Aging is a multifactorial condition that results in the loss of an organism's fitness over time. Different theories have been formulated to explain the mechanisms of aging, but a synthesis of these theories has not been possible until now. In addition, the increase in molecular data gathered by proteomics projects utilizing different organisms has permitted a better picture of proteins that function in aging. In this sense, the yeast Saccharomyces cerevisiae is a biological model for aging, and it shows two distinct aging states: a replicative state termed the replicative lifespan (RLS) and a quiescent state known as the chronological lifespan (CLS). Interestingly, both RLS and CLS appear to share common groups of proteins, but a combined model of both aging mechanisms has not been defined. Thus, by applying systems biology tools that allow mining of the yeast proteins associated with aging, it was possible to obtain an interactome network in which both RLS and CLS are represented. In addition, four subgraphs comprising ubiquitin-dependent proteasome/regulation of cell growth, nucleic acid metabolism, carbohydrate metabolism/RNA metabolism, and carbohydrate-organic acid-amino acid/DNA metabolism were found within the interactome, defining a new model of aging for yeast termed the chronologic-replicative protein network (CRPN).     

大肠杆菌poly(A)化mRNA cDNA文库的构建与鉴定

目的构建和鉴定大肠杆菌poly(A)化mRNA的cDNA文库。方法应用限制性显示PCR技术构建大肠杆菌poly(A)化mRNA的cDNA文库,筛选、收集cDNA片段,并进行测序。根据测序结果进行初步的生物信息学分析和结果验证。结果构建了大肠杆菌poly(A)化mRNA的限制性cDNA文库,并对其中66个基因片段进行了分析。结论所构建的大肠杆菌poly(A)化mRNA的cDNA文库片段重复性低,质量高。     

CPEB regulation of human cellular senescence, energy metabolism, and p53 mRNA translation

Cytoplasmic polyadenylation element-binding protein (CPEB) stimulates polyadenylation and translation in germ cells and neurons. Here, we show that CPEB-regulated translation is essential for the senescence of human diploid fibroblasts. Knockdown of CPEB causes skin and lung cells to bypass the M1 crisis stage of senescence; reintroduction of CPEB into the knockdown cells restores a senescence-like phenotype. Knockdown cells that have bypassed senescence undergo little telomere erosion. Surprisingly, knockdown of exogenous CPEB that induced a senescence-like phenotype results in the resumption of cell growth. CPEB knockdown cells have fewer mitochondria than wild-type cells and resemble transformed cells by having reduced respiration and reactive oxygen species (ROS), normal ATP levels, and enhanced rates of glycolysis. p53 mRNA contains cytoplasmic polyadenylation elements in its 3′ untranslated region (UTR), which promote polyadenylation. In CPEB knockdown cells, p53 mRNA has an abnormally short poly(A) tail and a reduced translational efficiency, resulting in an ~50% decrease in p53 protein levels. An shRNA-directed reduction in p53 protein by about 50% also results in extended cellular life span, reduced respiration and ROS, and increased glycolysis. Together, these results suggest that CPEB controls senescence and bioenergetics in human cells at least in part by modulating p53 mRNA polyadenylation-induced translation.