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Ramin Shiekhattar

Bio: Ramin Shiekhattar is an academic researcher from University of Miami. The author has contributed to research in topics: Chromatin & Enhancer. The author has an hindex of 64, co-authored 119 publications receiving 29981 citations. Previous affiliations of Ramin Shiekhattar include Wistar Institute & Barcelona Biomedical Research Park.


Papers
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Journal ArticleDOI
TL;DR: The most complete human lncRNA annotation to date is presented, produced by the GENCODE consortium within the framework of the ENCODE project and comprising 9277 manually annotated genes producing 14,880 transcripts, and expression correlation analysis indicates that lncRNAs show particularly striking positive correlation with the expression of antisense coding genes.
Abstract: The human genome contains many thousands of long noncoding RNAs (lncRNAs). While several studies have demonstrated compelling biological and disease roles for individual examples, analytical and experimental approaches to investigate these genes have been hampered by the lack of comprehensive lncRNA annotation. Here, we present and analyze the most complete human lncRNA annotation to date, produced by the GENCODE consortium within the framework of the ENCODE project and comprising 9277 manually annotated genes producing 14,880 transcripts. Our analyses indicate that lncRNAs are generated through pathways similar to that of protein-coding genes, with similar histone-modification profiles, splicing signals, and exon/intron lengths. In contrast to protein-coding genes, however, lncRNAs display a striking bias toward two-exon transcripts, they are predominantly localized in the chromatin and nucleus, and a fraction appear to be preferentially processed into small RNAs. They are under stronger selective pressure than neutrally evolving sequences-particularly in their promoter regions, which display levels of selection comparable to protein-coding genes. Importantly, about one-third seem to have arisen within the primate lineage. Comprehensive analysis of their expression in multiple human organs and brain regions shows that lncRNAs are generally lower expressed than protein-coding genes, and display more tissue-specific expression patterns, with a large fraction of tissue-specific lncRNAs expressed in the brain. Expression correlation analysis indicates that lncRNAs show particularly striking positive correlation with the expression of antisense coding genes. This GENCODE annotation represents a valuable resource for future studies of lncRNAs.

4,291 citations

Journal ArticleDOI
11 Nov 2004-Nature
TL;DR: In vivo knock-down and in vitro reconstitution studies revealed that both components of this smaller complex, termed Microprocessor, are necessary and sufficient in mediating the genesis of miRNAs from the primary miRNA transcript.
Abstract: MicroRNAs (miRNAs) are a growing family of small non-protein-coding regulatory genes that regulate the expression of homologous target-gene transcripts. They have been implicated in the control of cell death and proliferation in flies, haematopoietic lineage differentiation in mammals, neuronal patterning in nematodes and leaf and flower development in plants. miRNAs are processed by the RNA-mediated interference machinery. Drosha is an RNase III enzyme that was recently implicated in miRNA processing. Here we show that human Drosha is a component of two multi-protein complexes. The larger complex contains multiple classes of RNA-associated proteins including RNA helicases, proteins that bind double-stranded RNA, novel heterogeneous nuclear ribonucleoproteins and the Ewing's sarcoma family of proteins. The smaller complex is composed of Drosha and the double-stranded-RNA-binding protein, DGCR8, the product of a gene deleted in DiGeorge syndrome. In vivo knock-down and in vitro reconstitution studies revealed that both components of this smaller complex, termed Microprocessor, are necessary and sufficient in mediating the genesis of miRNAs from the primary miRNA transcript.

2,729 citations

Journal ArticleDOI
04 Aug 2005-Nature
TL;DR: It is shown that TRBP, which contains three double-stranded, RNA-binding domains, is an integral component of a Dicer-containing complex, and depletion of the Dicer–TRBP complex via exogenously introduced siRNAs diminished RISC-mediated reporter gene silencing.
Abstract: MicroRNAs (miRNAs) are generated by a two-step processing pathway to yield RNA molecules of approximately 22 nucleotides that negatively regulate target gene expression at the post-transcriptional level. Primary miRNAs are processed to precursor miRNAs (pre-miRNAs) by the Microprocessor complex. These pre-miRNAs are cleaved by the RNase III Dicer to generate mature miRNAs that direct the RNA-induced silencing complex (RISC) to messenger RNAs with complementary sequence. Here we show that TRBP (the human immunodeficiency virus transactivating response RNA-binding protein), which contains three double-stranded, RNA-binding domains, is an integral component of a Dicer-containing complex. Biochemical analysis of TRBP-containing complexes revealed the association of Dicer-TRBP with Argonaute 2 (Ago2), the catalytic engine of RISC. The physical association of Dicer-TRBP and Ago2 was confirmed after the isolation of the ternary complex using Flag-tagged Ago2 cell lines. In vitro reconstitution assays demonstrated that TRBP is required for the recruitment of Ago2 to the small interfering RNA (siRNA) bound by Dicer. Knockdown of TRBP results in destabilization of Dicer and a consequent loss of miRNA biogenesis. Finally, depletion of the Dicer-TRBP complex via exogenously introduced siRNAs diminished RISC-mediated reporter gene silencing. These results support a role of the Dicer-TRBP complex not only in miRNA processing but also as a platform for RISC assembly.

2,128 citations

Journal ArticleDOI
01 Oct 2010-Cell
TL;DR: An unanticipated role for a class of long ncRNAs in activation of critical regulators of development and differentiation is found in human cell lines.

1,643 citations

Journal ArticleDOI
TL;DR: It was evident that multiple mechanistic steps lead to the stable heritance of the epigenetic phenotype.
Abstract: A recent meeting (December 2008) regarding chromatin-based epigenetics was hosted by the Banbury Conference Center and Cold Spring Harbor Laboratory. The intent was to discuss aspects of epigenetic control of genomic function, and to arrive at a consensus definition of "epigenetics" to be considered by the broader community. It was evident that multiple mechanistic steps lead to the stable heritance of the epigenetic phenotype. Below we provide our view and interpretation of the proceedings at the meeting.

1,640 citations


Cited by
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Journal ArticleDOI
06 Sep 2012-Nature
TL;DR: The Encyclopedia of DNA Elements project provides new insights into the organization and regulation of the authors' genes and genome, and is an expansive resource of functional annotations for biomedical research.
Abstract: The human genome encodes the blueprint of life, but the function of the vast majority of its nearly three billion bases is unknown. The Encyclopedia of DNA Elements (ENCODE) project has systematically mapped regions of transcription, transcription factor association, chromatin structure and histone modification. These data enabled us to assign biochemical functions for 80% of the genome, in particular outside of the well-studied protein-coding regions. Many discovered candidate regulatory elements are physically associated with one another and with expressed genes, providing new insights into the mechanisms of gene regulation. The newly identified elements also show a statistical correspondence to sequence variants linked to human disease, and can thereby guide interpretation of this variation. Overall, the project provides new insights into the organization and regulation of our genes and genome, and is an expansive resource of functional annotations for biomedical research.

13,548 citations

Journal ArticleDOI
23 Feb 2007-Cell
TL;DR: The surface of nucleosomes is studded with a multiplicity of modifications that can dictate the higher-order chromatin structure in which DNA is packaged and can orchestrate the ordered recruitment of enzyme complexes to manipulate DNA.

10,046 citations

Journal Article
01 Jan 2012-Nature
TL;DR: The Encyclopedia of DNA Elements project provides new insights into the organization and regulation of the authors' genes and genome, and is an expansive resource of functional annotations for biomedical research.
Abstract: The human genome encodes the blueprint of life, but the function of the vast majority of its nearly three billion bases is unknown. The Encyclopedia of DNA Elements (ENCODE) project has systematically mapped regions of transcription, transcription factor association, chromatin structure and histone modification. These data enabled us to assign biochemical functions for 80% of the genome, in particular outside of the well-studied protein-coding regions. Many discovered candidate regulatory elements are physically associated with one another and with expressed genes, providing new insights into the mechanisms of gene regulation. The newly identified elements also show a statistical correspondence to sequence variants linked to human disease, and can thereby guide interpretation of this variation. Overall, the project provides new insights into the organization and regulation of our genes and genome, and is an expansive resource of functional annotations for biomedical research.

8,106 citations

Journal ArticleDOI
TL;DR: MiRNA-expression profiling of human tumours has identified signatures associated with diagnosis, staging, progression, prognosis and response to treatment and has been exploited to identify miRNA genes that might represent downstream targets of activated oncogenic pathways, or that target protein-coding genes involved in cancer.
Abstract: MicroRNA (miRNA ) alterations are involved in the initiation and progression of human cancer. The causes of the widespread differential expression of miRNA genes in malignant compared with normal cells can be explained by the location of these genes in cancer-associated genomic regions, by epigenetic mechanisms and by alterations in the miRNA processing machinery. MiRNA-expression profiling of human tumours has identified signatures associated with diagnosis, staging, progression, prognosis and response to treatment. In addition, profiling has been exploited to identify miRNA genes that might represent downstream targets of activated oncogenic pathways, or that target protein- coding genes involved in cancer.

6,345 citations

Journal Article
TL;DR: The causes of the widespread differential expression of miRNA genes in malignant compared with normal cells can be explained by the location of these genes in cancer-associated genomic regions, by epigenetic mechanisms and by alterations in the miRNA processing machinery as discussed by the authors.
Abstract: MicroRNA (miRNA) alterations are involved in the initiation and progression of human cancer. The causes of the widespread differential expression of miRNA genes in malignant compared with normal cells can be explained by the location of these genes in cancer-associated genomic regions, by epigenetic mechanisms and by alterations in the miRNA processing machinery. MiRNA-expression profiling of human tumours has identified signatures associated with diagnosis, staging, progression, prognosis and response to treatment. In addition, profiling has been exploited to identify miRNA genes that might represent downstream targets of activated oncogenic pathways, or that target protein- coding genes involved in cancer.

6,306 citations