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Transcription-dependent nucleocytoplasmic distribution of hnRNP A1 protein in early mouse embryos.
J Cell Sci. 2001 Apr; 114(Pt 8):1521-31.JC

Abstract

A unique feature of certain members of the heterogeneous nuclear ribonucleoprotein (hnRNP) family of proteins is that they shuttle continuously between nucleus and cytoplasm and their accumulation in the nucleus is transcription-dependent. An extensively characterised protein of this group is hnRNP A1. To date, most studies addressing the transcription-dependent transport of hnRNP A1 have been performed on cultured cell lines treated with transcription inhibitors. Here we have analysed the nucleocytoplasmic distribution of hnRNP A1 in early mouse embryos, where the haploid pronuclei remain transcriptionally inactive for a period of several hours. Consistent with its small molecular size (36 kDa), the hnRNP A1 protein diffuses passively through the nuclear pores and equilibrates between the nucleus and the cytoplasm of transcriptionally inactive embryos. In contrast, following transcriptional activation the A1 protein becomes accumulated in the nucleus. This accumulation of the A1 protein in the nucleus is blocked by the lectin wheat germ agglutinin (WGA), which binds to nuclear pore proteins and prevents translocation of receptor-cargo complexes through the pores. This indicates that a carrier-mediated transport pathway is required for the concentration of A1 in transcriptionally active nuclei. To further analyse how transcription is coupled to nucleocytoplasmic transport, we transplanted transcriptionally inactive pronuclei into the cytoplasm of transcriptionally active embryos. The results show that the presence of newly synthesised RNAs in the cytoplasm is not sufficient to induce the accumulation of hnRNP A1 in the nucleus. Rather, the appearance of nascent transcripts in the nucleus appears to be the crucial event. Since hnRNP A1 is a shuttling protein, an increase in its steady state nuclear concentration could be the result of either faster nuclear import or slower export to the cytoplasm. We propose that binding of A1 to nascent transcripts retards its export to the cytoplasm and therefore contributes to its concentration in the nucleus.

Authors+Show Affiliations

Institute of Histology and Embryology, Faculty of Medicine, University of Lisbon, Portugal.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

11282028

Citation

Vautier, D, et al. "Transcription-dependent Nucleocytoplasmic Distribution of hnRNP A1 Protein in Early Mouse Embryos." Journal of Cell Science, vol. 114, no. Pt 8, 2001, pp. 1521-31.
Vautier D, Chesné P, Cunha C, et al. Transcription-dependent nucleocytoplasmic distribution of hnRNP A1 protein in early mouse embryos. J Cell Sci. 2001;114(Pt 8):1521-31.
Vautier, D., Chesné, P., Cunha, C., Calado, A., Renard, J. P., & Carmo-Fonseca, M. (2001). Transcription-dependent nucleocytoplasmic distribution of hnRNP A1 protein in early mouse embryos. Journal of Cell Science, 114(Pt 8), 1521-31.
Vautier D, et al. Transcription-dependent Nucleocytoplasmic Distribution of hnRNP A1 Protein in Early Mouse Embryos. J Cell Sci. 2001;114(Pt 8):1521-31. PubMed PMID: 11282028.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Transcription-dependent nucleocytoplasmic distribution of hnRNP A1 protein in early mouse embryos. AU - Vautier,D, AU - Chesné,P, AU - Cunha,C, AU - Calado,A, AU - Renard,J P, AU - Carmo-Fonseca,M, PY - 2001/4/3/pubmed PY - 2001/7/4/medline PY - 2001/4/3/entrez SP - 1521 EP - 31 JF - Journal of cell science JO - J Cell Sci VL - 114 IS - Pt 8 N2 - A unique feature of certain members of the heterogeneous nuclear ribonucleoprotein (hnRNP) family of proteins is that they shuttle continuously between nucleus and cytoplasm and their accumulation in the nucleus is transcription-dependent. An extensively characterised protein of this group is hnRNP A1. To date, most studies addressing the transcription-dependent transport of hnRNP A1 have been performed on cultured cell lines treated with transcription inhibitors. Here we have analysed the nucleocytoplasmic distribution of hnRNP A1 in early mouse embryos, where the haploid pronuclei remain transcriptionally inactive for a period of several hours. Consistent with its small molecular size (36 kDa), the hnRNP A1 protein diffuses passively through the nuclear pores and equilibrates between the nucleus and the cytoplasm of transcriptionally inactive embryos. In contrast, following transcriptional activation the A1 protein becomes accumulated in the nucleus. This accumulation of the A1 protein in the nucleus is blocked by the lectin wheat germ agglutinin (WGA), which binds to nuclear pore proteins and prevents translocation of receptor-cargo complexes through the pores. This indicates that a carrier-mediated transport pathway is required for the concentration of A1 in transcriptionally active nuclei. To further analyse how transcription is coupled to nucleocytoplasmic transport, we transplanted transcriptionally inactive pronuclei into the cytoplasm of transcriptionally active embryos. The results show that the presence of newly synthesised RNAs in the cytoplasm is not sufficient to induce the accumulation of hnRNP A1 in the nucleus. Rather, the appearance of nascent transcripts in the nucleus appears to be the crucial event. Since hnRNP A1 is a shuttling protein, an increase in its steady state nuclear concentration could be the result of either faster nuclear import or slower export to the cytoplasm. We propose that binding of A1 to nascent transcripts retards its export to the cytoplasm and therefore contributes to its concentration in the nucleus. SN - 0021-9533 UR - https://www.unboundmedicine.com/medline/citation/11282028/Transcription_dependent_nucleocytoplasmic_distribution_of_hnRNP_A1_protein_in_early_mouse_embryos_ DB - PRIME DP - Unbound Medicine ER -