Energy requirement and kineties of transport of poly(A)‐free histone mRNA compared to poly(A)‐rich mRNA from isolated L‐cell nuclei

Schröder, Heinz C.; Friese, Ursula; Bachmann, Michael; Zaubitzer, Thomas; Müller, Wernér E.G.

doi:10.1111/j.1432-1033.1989.tb14706.x

Cited by 21 publications

(13 citation statements)

References 59 publications

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“…Release of endogenous RNA from isolated mammalian nuclei has been studied previously and found to be not strictly dependent on energy, but in these studies neither integrity of nuclear envelope nor intactness of RNA was carefully controlled (2,45). More recently, synthetic nuclei assembled in Xenopus egg extracts on paramagnetic DNA-coated beads containing a U1 template were shown to transcribe U1 RNA and support U1 nuclear export in a temperature-and energy-dependent manner.…”

Section: Discussionmentioning

confidence: 99%

RanGTP-Binding Protein NXT1 Facilitates Nuclear Export of Different Classes of RNA In Vitro

Ossareh-Nazari

Maison

Black

et al. 2000

Molecular and Cellular Biology

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To better characterize the mechanisms responsible for RNA export from the nucleus, we developed an in vitro assay based on the use of permeabilized HeLa cells. This new assay supports nuclear export of U1 snRNA, tRNA, and mRNA in an energy-and Xenopus extract-dependent manner. U1 snRNA export requires a 5 monomethylated cap structure, the nuclear export signal receptor CRM1, and the small GTPase Ran. In contrast, mRNA export does not require the participation of CRM1. We show here that NXT1, an NTF2-related protein that binds directly to RanGTP, strongly stimulates export of U1 snRNA, tRNA, and mRNA. The ability of NXT1 to promote export is dependent on its capacity to bind RanGTP. These results support the emerging view that NXT1 is a general export factor, functioning on both CRM1-dependent and CRM1-independent pathways of RNA export.In eukaryotic cells, molecular exchanges between the nucleus and the cytoplasm occur through the nuclear pore complex (NPC). Members of the karyopherin ␤ family, also known as importins and exportins, specifically interact with cargos and mediate their nuclear import and nuclear export, respectively (33, 52). Nucleocytoplasmic transport also requires the small GTPase Ran (35, 37). The compartmentalization of the RanGDP exchange factor RCC1 in the nucleus (38) and the RanGTPase-activating protein (RanGAP) in the cytoplasm (17) is thought to provide a steep gradient of RanGDP (cytoplasmic)/RanGTP (nuclear) across the nuclear envelope that ensures the directionality of nuclear transport. More precisely, importins bind their import substrates in the absence of RanGTP (in the cytoplasm) and release them upon binding to RanGTP (in the nucleus) (34). In contrast, exportins interact with export cargos in a RanGTP-dependent manner (in the nucleus), and GTP hydrolysis on Ran in the cytoplasm triggers dissociation of exportin-cargo complexes (33).Nearly all nucleus-encoded RNAs require export to the cytoplasm as part of their maturation process or biosynthetic function. RNAs are transported as ribonucleoprotein (RNP) complexes, and considerable effort has been devoted to understanding the protein-and RNA-based signals that specify export to the cytoplasm. Mature tRNA are directly recognized by a karyopherin ␤-like export receptor, exportin t or Los1p, in a RanGTP-dependent manner (4,16,28,31). Transport of spliceosomal U snRNAs depends on their 5Ј monomethylated cap structure, a cis-acting nuclear export signal (NES) that interacts with a nuclear cap-binding complex (CBC) composed of CBP20 and CBP80 (15,20). The leucine-rich nuclear export receptor, CRM1 or exportin 1 (12, 39, 48), in cooperation with RanGTP is required for the transport of U snRNAs and CBC to the cytoplasm, but it remains unclear whether CBC, CRM1, and RanGTP represent the minimal machinery responsible for the nuclear export of U snRNAs (11). CRM1 is also responsible for the nuclear export of human immunodeficiency virus (HIV) mRNAs that contain a Rev-responsive element, recognized by the NES-containing HIV Rev protein (9-1...

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Section: Discussionmentioning

confidence: 99%

RanGTP-Binding Protein NXT1 Facilitates Nuclear Export of Different Classes of RNA In Vitro

Ossareh-Nazari

Maison

Black

et al. 2000

Molecular and Cellular Biology

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“…Thus, synthesis and export do not appear to be obligatorily coupled. To confirm that the transcripts isolated with the nuclear fraction were located within the nuclear envelope, we examined the effect of adding WGA, which inhibits export of RNAs (4,78,79 Triming at the 3' ends of pre-snRNAs. As is evident in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The speed with which pre-snRNAs are exported remains unexplained but is probably related to the lack of posttranscriptional modifications of pre-snRNAs in the nucleus, since extensive nuclear processing may delay the export of mRNAs and tRNA (83; reviewed in references 1 and 77). The exit of mRNAs and tRNAs, as well as the import of macromolecules into the nucleus, is inhibited by WGA, which binds to N-acetylglycosamine in nuclear pore glycoproteins (4,14,22,64,78,79,89,90; J. G. Koster and M. Zasloff, personal communication). We have confirmed that the exit of pre-snRNAs also is inhibited by WGA and thus depends on the function of a glycoprotein that contains N-acetylglucosamine (E. Lund VOL.…”

Section: Discussionmentioning

confidence: 99%

Nucleocytoplasmic transport and processing of small nuclear RNA precursors.

Vegvar¹,

Dahlberg²

1990

Mol. Cell. Biol.

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We have analyzed the structures and locations of small nuclear RNA (snRNA) precursors at various stages in their synthesis and maturation. In the nuclei of pulse-labeled Xenopus laevis oocytes, we detected snRNAs that were longer than their mature forms at their 3' ends by up to 10 nucleotides. Analysis of the 5' caps of these RNAs and pulse-chase experiments showed that these nuclear snRNAs were precursors of the cytoplasmic pre-snRNAs that have been observed in the past. Synthesis of pre-snRNAs was not abolished by wheat germ agglutinin, which inhibits export of the pre-snRNAs from the nucleus, indicating that synthesis of these RNAs is not obligatorily coupled to their export. Newly synthesized Ul RNAs could be exported from the nucleus regardless of the length of the 3' extension, but pre-Ul RNAs that were elongated at their 3' ends by more than about 10 nucleotides were poor substrates for trimming in the cytoplasm. The structure at the 3' end was critical for subsequent transport of the RNA back to the nucleus. This requirement ensures that truncated and incompletely processed Ul RNAs are excluded from the nucleus.Small nuclear RNAs (snRNAs) are essential components of the small nuclear ribonucleoprotein particles (snRNPs) involved in processing mRNA precursors (reviewed in references 6, 53, and 81). Synthesis and processing of snRNAs and their assembly into snRNPs involve many steps in both the nucleus and the cytoplasm (reviewed in references 55 and 65). Precursors of snRNAs Ul to U5 (pre-snRNAs) are transcribed by RNA polymerase II from families of multiple genes (reviewed in reference 15). The 3' ends of these presnRNAs are made in a promoter-specific manner in response to a 3'-end signal downstream from each RNA coding region (11,32,63). Initially, they have 7-methylguanosine (m7G) caps at their 5' ends (32, 49, 54, 80; this paper) and 1 to 10 extra nucleotides at their 3' ends compared with the mature snRNAs that accumulate in the nucleus (19,50,51).Although experiments with isolated nuclei have confirmed the nucleus as the site of their transcription (39,44,49), the pre-snRNAs have been detected in vivo only in the cytoplasm (18,19,30,50,51,94, 96). One possible explanation for the difficulty in finding pre-snRNAs in the nucleus might be leakage while the nuclei and cytoplasms were being separated (18, 50). Other explanations involve the coupling of pre-snRNA export to transcription (15). This situation contrasts with that of mRNA and tRNA export, which takes place only after processing of precursors has occurred in the nucleus (83; reviewed in references 1, 12, and 77). Several lines of evidence indicate that RNAs are exported from the nucleus through nuclear pores. For example, the lectin wheat germ agglutinin (WGA), which binds to N-acetylglucosamine residues found in the glycoproteins of nuclear pores, has been shown to inhibit the export of 5S RNA, tRNA, mRNA, and pre-snRNAs (4, 78, 79; E. Lund and J. E. Dahlberg, unpublished data; J. G. Koster and M. Zasloff, personal communication).Free prote...

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“…1B). mRNA export from the nucleus to the cytoplasm requires about 10–30 min depending on the mRNA (Schroder et al, 1989; Fuke and Ohno, 2008). This induces another delay in the response to transcriptional activation, since the mRNA can be translated into a protein only once it is exported from the nucleus and binds to the ribosomes.…”

Section: Transcriptional Kineticsmentioning

confidence: 99%

Modeling the dynamics of transcriptional gene regulatory networks for animal development

de-Leon

Davidson

2009

Developmental Biology

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The dynamic process of cell fate specification is regulated by networks of regulatory genes. The architecture of the network defines the temporal order of specification events. To understand the dynamic control of the developmental process, the kinetics of mRNA and protein synthesis and the response of the cis-regulatory modules to transcription factor concentration must be considered. Here we review mathematical models for mRNA and protein synthesis kinetics which are based on experimental measurements of the rates of the relevant processes. The model comprises the response functions of cis-regulatory modules to their transcription factor inputs, by incorporating binding site occupancy and its dependence on biologically measurable quantities. We use this model to simulate gene expression, to distinguish between cis-regulatory execution of “AND” and “OR” logic functions, rationalize the oscillatory behavior of certain transcriptional auto-repressors and to show how linked subcircuits can be dealt with. Model simulations display the effects of mutation of binding sites, or perturbation of upstream gene expression. The model is a generally useful tool for understanding gene regulation and the dynamics of cell fate specification.

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Energy requirement and kineties of transport of poly(A)‐free histone mRNA compared to poly(A)‐rich mRNA from isolated L‐cell nuclei

Cited by 21 publications

References 59 publications

RanGTP-Binding Protein NXT1 Facilitates Nuclear Export of Different Classes of RNA In Vitro

RanGTP-Binding Protein NXT1 Facilitates Nuclear Export of Different Classes of RNA In Vitro

Nucleocytoplasmic transport and processing of small nuclear RNA precursors.

Modeling the dynamics of transcriptional gene regulatory networks for animal development

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