Topic
Intron
About: Intron is a research topic. Over the lifetime, 23850 publications have been published within this topic receiving 1305164 citations. The topic is also known as: introns.
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TL;DR: Five sequences coding for proteins homologous to components of the respiratory‐chain NADH dehydrogenase from human mitochondria have been found and sequence and expression analyses indicate both prokaryotic and eukaryotic features of the chloroplast genes.
Abstract: The complete nucleotide sequence (155 844 bp) of tobacco (Nicotiana tabacum var. Bright Yellow 4) chloroplast DNA has been determined. It contains two copies of an identical 25 339 bp inverted repeat, which are separated by a 86 684 bp and a 18 482 bp single-copy region. The genes for 4 different rRNAs, 30 different tRNAs, 39 different proteins and 11 other predicted protein coding genes have been located. Among them, 15 genes contain introns. Blot hybridization revealed that all rRNA and tRNA genes and 27 protein genes so far analysed are transcribed in the chloroplast and that primary transcripts of the split genes hitherto examined are spliced. Five sequences coding for proteins homologous to components of the respiratory-chain NADH dehydrogenase from human mitochondria have been found. The 30 tRNAs predicted from their genes are sufficient to read all codons if the ;two out of three' and ;U:N wobble' mechanisms operate in the chloroplast. Two sequences which autonomously replicate in yeast have also been mapped. The sequence and expression analyses indicate both prokaryotic and eukaryotic features of the chloroplast genes.
2,184 citations
TL;DR: A new role for circRNAs in regulating gene expression in the nucleus is revealed, in which EIciRNAs enhance the expression of their parental genes in cis, and a regulatory strategy for transcriptional control via specific RNA-RNA interaction between U1 snRNA and EICIRNAs is highlighted.
Abstract: Noncoding RNAs (ncRNAs) have numerous roles in development and disease, and one of the prominent roles is to regulate gene expression A vast number of circular RNAs (circRNAs) have been identified, and some have been shown to function as microRNA sponges in animal cells Here, we report a class of circRNAs associated with RNA polymerase II in human cells In these circRNAs, exons are circularized with introns 'retained' between exons; we term them exon-intron circRNAs or EIciRNAs EIciRNAs predominantly localize in the nucleus, interact with U1 snRNP and promote transcription of their parental genes Our findings reveal a new role for circRNAs in regulating gene expression in the nucleus, in which EIciRNAs enhance the expression of their parental genes in cis, and highlight a regulatory strategy for transcriptional control via specific RNA-RNA interaction between U1 snRNA and EIciRNAs
2,077 citations
TL;DR: It is proposed that the IVS portion of the RNA has several enzyme-like properties that enable it to break and reform phosphodiester bonds and that enzymes, small nuclear RNAs and folding of the pre-rRNA into an RNP are unnecessary for these reactions.
2,077 citations
TL;DR: It is strongly suggested that miRNAs are transcribed in parallel with their host transcripts, and that the two different transcription classes of miRNAAs ('exonic' and 'intronic') identified here may require slightly different mechanisms of biogenesis.
Abstract: To derive a global perspective on the transcription of microRNAs (miRNAs) in mammals, we annotated the genomic position and context of this class of noncoding RNAs (ncRNAs) in the human and mouse genomes. Of the 232 known mammalian miRNAs, we found that 161 overlap with 123 defined transcription units (TUs). We identified miRNAs within introns of 90 protein-coding genes with a broad spectrum of molecular functions, and in both introns and exons of 66 mRNA-like noncoding RNAs (mlncRNAs). In addition, novel families of miRNAs based on host gene identity were identified. The transcription patterns of all miRNA host genes were curated from a variety of sources illustrating spatial, temporal, and physiological regulation of miRNA expression. These findings strongly suggest that miRNAs are transcribed in parallel with their host transcripts, and that the two different transcription classes of miRNAs (`exonic' and `intronic') identified here may require slightly different mechanisms of biogenesis.
2,043 citations
TL;DR: By deep sequencing of RNA from a variety of normal and malignant human cells, this work suggests that a non-canonical mode of RNA splicing, resulting in a circular RNA isoform, is a general feature of the gene expression program in human cells.
Abstract: Most human pre-mRNAs are spliced into linear molecules that retain the exon order defined by the genomic sequence. By deep sequencing of RNA from a variety of normal and malignant human cells, we found RNA transcripts from many human genes in which the exons were arranged in a non-canonical order. Statistical estimates and biochemical assays provided strong evidence that a substantial fraction of the spliced transcripts from hundreds of genes are circular RNAs. Our results suggest that a non-canonical mode of RNA splicing, resulting in a circular RNA isoform, is a general feature of the gene expression program in human cells.
1,989 citations