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Results for “RNA Transport”

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At least 73 records · Page 4Linked to original sources
PubMed2001

Pur alpha protein implicated in dendritic RNA transport interacts with ribosomes in neuronal cytoplasm.

We have previously reported that pur alpha, known to be a regulator of DNA replication and transcription, links neural BC1 RNA to microtubules via dendrite-targeting RNA motifs. Here we demonstrate the subcellular localization of pur proteins within the brain. Pur proteins were detected in neurons but not in glia. Immunohistochemical staining was prominent in perikarya and proximal dendrites and also extended into primary dendritic processes, but no significant signals were detected in the distal regions of dendrite. When homogenates of mouse brain were fractionated, pur alpha was most concentrated in the microsomal pellet. Consistently, pur alpha co-fractionated with free polysomes as well as with membrane-bound polysomes and the association with polysomes was mediated by binding ribosomal subunits. Levels of ribosomes with pur alpha progressively increased during postnatal development of the brain.

Animals↗
PubMed1993

Evidence for channeled diffusion of pre-mRNAs during nuclear RNA transport in metazoans.

We report studies using an enhanced experimental system to investigate organization of nuclear pre-mRNA metabolism. It is based on the powerful genetic system and polytene nuclei of Drosophila. We observe (at steady state) movement of a specific pre-mRNA between its gene and the nuclear surface. This movement is isotropic, at rates consistent with diffusion and is restricted to a small nuclear subcompartment defined by exclusion from chromosome axes and the nucleolus. Bulk polyadenylated nuclear pre-mRNA precisely localizes in this same subcompartment indicating that most or all pre-mRNAs use the same route of intranuclear movement. In addition to association with nascent transcripts, snRNPs are coconcentrated with pre-mRNA in this subcompartment. In contrast to constitutive splices, at least one regulated splice occurs slowly and may undergo execution remotely from the site of pre-mRNA synthesis. Details of our results suggest that retention of incompletely spliced pre-mRNA is a function of the nuclear surface. We propose a simple model--based on channeled diffusion--for organization of intranuclear transport and metabolism of pre-mRNAs in polytene nuclei. We argue that this model can be generalized to all metazoan nuclei.

Animals↗
PubMed2006

CRM1, an RNA transporter, is a major species-specific restriction factor of human T cell leukemia virus type 1 (HTLV-1) in rat cells.

Rat ortholog of human CRM1 has been found to be responsible for the poor activity of viral Rex protein, which is essential for RNA export of human T cell leukemia virus type 1 (HTLV-1). Here, we examined the species-specific barrier of HTLV-1 by establishing rat cell lines, including both adherent and CD4(+) T cells, which express human CRM1 at physiological levels. We demonstrated that expression of human CRM1 in rat cells is not harmful to cell growth and is sufficient to restore the synthesis of the viral structural proteins, Gag and Env, at levels similar to those in human cells. Gag precursor proteins were efficiently processed to the mature forms in rat cells and released into the culture medium as sedimentable viral particles. An HTLV-1 pseudovirus infection system suggested that the released virus particles are fully infectious. Our newly developed reporter cell system revealed that Env proteins produced in rat cells are fully fusogenic, which is the basis for cell-cell HTLV-1 infection. Moreover, we show that the early steps in infection, from post-entry uncoating to integration into the host chromosomes, occur efficiently in rat cells. These results, in conjunction with reports describing efficient entry of HTLV-1 into rat cells, may indicate that HTLV-1 is unique in that its major species-specific barrier is determined by CRM1 at a viral RNA export step. These observations will enable us to construct a transgenic rat model expressing human CRM1 that is sensitive to HTLV-1 infection.

Adenocarcinoma↗