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.

/pdf/initial-sequencing-and-analysis-of-the-human-genome-5dapk1rsx1.pdf

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

The present invention relates to a Drosophila in vitro system which was used to demonstrate that dsRNA is processed to RNA segments 21-23 nucleotides (nt) in length. Furthermore, when these 21-23 nt fragments are purified and added back to Drosophila extracts, they mediate RNA interference in the absence of long dsRNA. Thus, these 21-23 nt fragments are the sequence-specific mediators of RNA degradation. A molecular signal, which may be their specific length, must be present in these 21-23 nt fragments to recruit cellular factors involved in RNAi. This present invention encompasses these 21-23 nt fragments and their use for specifically inactivating gene function. The use of these fragments (or chemically synthesized oligonucleotides of the same or similar nature) enables the targeting of specific mRNAs for degradation in mammalian cells, where the use of long dsRNAs to elicit RNAi is usually not practical, presumably because of the deleterious effects of the interferon response. This specific targeting of a particular gene function is useful in functional genomic and therapeutic applications.

Rna sequence-specific mediators of rna interference

RNA interference silences gene expression through short interfering 21 23-mer double-strand RNA segments that guide mRNA degradation in a sequence-specific fashion. Here we report that siRNAs inhibit virus production by targeting the mRNAs for either the HIV-1 cellular receptor CD4, the viral structural Gag protein or green fluorescence protein substituted for the Nef regulatory protein. siRNAs effectively inhibit pre- and/or post-integration infection events in the HIV-1 life cycle. Thus, siRNAs may have potential for therapeutic intervention in HIV-1 and other viral infections.

siRNA-directed inhibition of HIV-1 infection.

Short RNAs Repress Translation after Initiation in Mammalian Cells

In the few years since the discovery of RNA interference (RNAi; Fire et al. 1998), it has become clear that this process is ancient. RNAi, the oldest and most ubiquitous antiviral system, appeared before the divergence of plants and animals. Because aspects of RNAi, known as cosuppression, also control the expression of transposable elements and repetitive sequences (Ketting et al. 1999; Tabara et al. 1999), the interplay of RNAi and transposon activities have almost certainly shaped the structure of the genome of most organisms. Surprisingly, we are only now beginning to explore the molecular processes responsible for RNAi and to appreciate the breadth of its function in biology. Practical applications of this knowledge have allowed rapid surveys of gene functions (see Fraser et al. 2000 and Gönczey et al. 2000 for RNAi analysis of genes on chromosome I and III of Caenorhabditis elegans) and will possibly result in new therapeutic interventions. Genetic studies have expanded the biology of RNAi to cosuppression, transposon silencing, and the first hints of relationships to regulation of translation and development. The possible roles of RNA-dependent RNA polymerase (RdRp) in RNAi have been expanded. Many experiments indicate that dsRNA directs gene-specific methylation of DNA and, thus, regulation at the stage of transcription in plants. Cosuppression may involve regulation by polycomb complexes at the level of transcription in C. elegans and Drosophila. This article will review these topics and primarily summarize advances in the study of RNAi over the past year.

/pdf/rna-interference-2001-72pm3qdtkl.pdf

RNA interference—2001

https://stacks.cdc.gov/view/cdc/30747/cdc_30747_DS1.pdf

Phillip A. Sharp

Papers

Rna sequence-specific mediators of rna interference

siRNA-directed inhibition of HIV-1 infection.

Short RNAs Repress Translation after Initiation in Mammalian Cells

RNA interference—2001

Genome-wide CRISPR screen in a mouse model of tumor growth and metastasis