MicroRNAs: Genomics, Biogenesis, Mechanism, and Function

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

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Initial sequencing and analysis of the human genome.

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

http://bartellab.wi.mit.edu/publication_reprints/Bartel_Cell09.pdf

MicroRNAs: Target Recognition and Regulatory Functions

A procedure for extracting plasmid DNA from bacterial cells is described. The method is simple enough to permit the analysis by gel electrophoresis of 100 or more clones per day yet yields plasmid DNA which is pure enough to be digestible by restriction enzymes. The principle of the method is selective alkaline denaturation of high molecular weight chromosomal DNA while covalently closed circular DNA remains double-stranded. Adequate pH control is accomplished without using a pH meter. Upon neutralization, chromosomal DNA renatures to form an insoluble clot, leaving plasmid DNA in the supernatant. Large and small plasmid DNAs have been extracted by this method.

A rapid alkaline extraction procedure for screening recombinant plasmid DNA

We describe the results of our studies of expression of a Saccharomyces cerevisiae amber suppressor tRNA(Leu) gene (SUP53) in mammalian cells in vivo and in cell extracts in vitro. Parallel studies were carried out with the wild-type (Su-) tRNA(Leu) gene. Extracts from HeLa or CV1 cells transcribed both tRNA(Leu) genes. The transcripts were processed correctly at the 5' and 3' ends and accurately spliced to produce mature tRNA(Leu). Surprisingly, when the same tRNA(Leu) genes were introduced into CV1 cells, only pre-tRNAs(Leu) were produced. The pre-tRNAs(Leu) made in vivo were of the same size and contained the 5'-leader and 3'-trailer sequences as did pre-tRNAs(Leu) made in vitro. Furthermore, the pre-tRNAs(Leu) made in vivo were processed to mature tRNA(Leu) when incubated with HeLa cell extracts. A tRNA(Leu) gene from which the intervening sequence had been removed yielded RNAs that also were not processed at either their 5' or 3' termini. Thus, processing of pre-tRNA(Leu) in CV1 cells is blocked at the level of 5'- and 3'-end maturation. One possible explanation of the discrepancy in the results obtained in vivo and in vitro is that tRNA biosynthesis in mammalian cells involves transport of pre-tRNA from the site of its synthesis to a site or sites where processing takes place, and perhaps the yeast pre-tRNAs(Leu) synthesized in CV1 cells are not transported to the appropriate site.

Saccharomyces cerevisiae SUP53 tRNA gene transcripts are processed by mammalian cell extracts in vitro but are not processed in vivo.

The invention relates in aspects to hybrid RNAs lacking a poly-A tail and nucleic acid vectors for expressing the RNA. The hybrid RNAs in some instances have a 3' terminal stabilizing triple helical structure. Related methods for expressing said RNAs in vivo and in vitro are also disclosed.

Production of stable non-polyadenylated RNAs

OVERVIEW Initiation of transcription by RNA polymerase II (pol II) requires the formation of a complex containing the basal factors TFIID, TFIIB, TFIIE/F, and polymerase. Additional factors have been suggested as important for initiation, and the relationship among these factors has not been well defined. The initiation complex is assembled in an ordered pathway commencing with the binding of TFIID and TFIIA to the TATA element. Interactions between polymerase and TFIIF in solution stimulate the binding of polymerase to the template-associated complex containing TFIID and TFIIB. This interaction also generates a polymerase-DNA conformation similar to that previously characterized for “open” prokaryotic polymerase-promoter complexes. Such a complex can rapidly initiate transcription, and its formation is rate-limiting for many prokaryotic promoters. Transcription factors that bind specific sequences in the vicinity of a promoter stimulate or suppress the rate of initiation through modulation of the basal reaction. The rate-limiting step in this basal process probably varies between different promoters, and thus there may be multiple mechanisms by which transcription factors regulate initiation. INTRODUCTION Intricate and important processes such as development and oncogenesis cannot be understood without considering the process of transcription initiation in some detail. A sufficiently precise model may soon be at hand. Several of the general transcription factors have been cloned, and the molecular events leading to transcription initiation by RNA pol II are slowly emerging. The model of initiation presented here is based on studies using a minimal pol II promoter, defined as a TATA element and an initiation site....

9 Initiation of Transcription by RNA Polymerase II

Mechanisms involved in copper uptake by human intestinal epithelial cells.

http://link.springer.com/content/pdf/10.1007/978-3-642-71635-5_44.pdf

Phillip A. Sharp

Papers

Saccharomyces cerevisiae SUP53 tRNA gene transcripts are processed by mammalian cell extracts in vitro but are not processed in vivo.

Production of stable non-polyadenylated RNAs

9 Initiation of Transcription by RNA Polymerase II

Mechanisms involved in copper uptake by human intestinal epithelial cells.

Inherited Peroxisomal Disorders: Defects in the Oxidation of Very Long Chain Fatty Acids and Phytanic Acid