Messenger RNA Processing in Eukaryotes

Eucaryotic messenger RNA precursors are processed in nuclear ribonucleoprotein particles (hnRNP). Here recent work on the structure of hnRNP is reviewed, with emphasis on function. Detailed analysis of a specific case, the altered assembly of hnRNP in heat-shocked Drosophila and mammalian cells, leads to a general hypothesis linking hnRNP structure and messenger RNA processing.

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Ultrastructural analysis of early pre-messenger RNA processing events using the Miller chromatin spreading method

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100123179 ◽

1992 ◽

Vol 50 (1) ◽

pp. 554-555

Author(s):

Ann Beyer ◽

Yvonne Osheim

Keyword(s):

Rna Processing ◽

Messenger Rna ◽

Structural Features ◽

Ultrastructural Analysis ◽

Electron Microscopic ◽

Mrna Transcripts ◽

Carbon Coated ◽

Nascent Transcripts ◽

Active Genes

We use the Miller chromatin spreading technique for electron microscopic visualization of transcriptionally active genes. In this method, cells are hypotonically disrupted and cellular contents are diluted into water at pH 8-9 and fixed with formaldehyde. The dispersed cellular contents are centrifuged onto a carbon-coated EM grid; the majority of the material that is deposited on the grid consists of entangled masses of dispersed chromatin, some regions of which are transcriptionally active (Fig 1). Our interests lie in ultrastructural analysis of co-transcriptional RNA processing events on pre-mRNA transcripts, which we analyze by mapping structural features on successive nascent transcripts on a given gene. The two processing events that we have been able to study by this approach are the removal of introns by splicing and generation of the 3’ end of the transcript.

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An RNA exosome subunit mediates cell-to-cell trafficking of a homeobox mRNA via plasmodesmata

Science ◽

10.1126/science.abm0840 ◽

2022 ◽

Vol 375 (6577) ◽

pp. 177-182

Author(s):

Munenori Kitagawa ◽

Peipei Wu ◽

Rachappa Balkunde ◽

Patrick Cunniff ◽

David Jackson

Keyword(s):

Ribosomal Rna ◽

Rna Processing ◽

Messenger Rna ◽

Plant Cells ◽

Cell Trafficking ◽

Cell Transport ◽

Homeobox Transcription Factor ◽

A Subunit ◽

Ribosomal Rna Processing ◽

Rna Exosome

mRNA migration through plasmodesmata In plants, certain transcription factors are produced in one cell but transported, sometimes as messenger RNA (mRNA), through plasmodesmata, channels between neighboring plant cells, where they act. This system helps to manage stem cell development. Kitagawa et al . now identify part of the machinery that manages this cell-to-cell transport. Transport of the mRNA encoding the KNOTTED1 homeobox transcription factor depends on Ribosomal RNA-Processing Protein 44 (AtRRP44A), which is a subunit of the RNA exosome. —PJH

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