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CRM1 and its ribosome export adaptor NMD3 localize to the nucleolus and affect rRNA synthesis.
Nucleus 2013 Jul-Aug; 4(4):315-25N

Abstract

CRM1 is an export factor that together with its adaptor NMD3 transports numerous cargo molecules from the nucleus to cytoplasm through the nuclear pore. Previous studies have suggested that CRM1 and NMD3 are detected in the nucleolus. However, their localization with subnucleolar domains or participation in the activities of the nucleolus are unclear. We demonstrate here biochemically and using imaging analyses that CRM1 and NMD3 co-localize with nucleolar marker proteins in the nucleolus. In particular, their nucleolar localization is markedly increased by inhibition of RNA polymerase I (Pol I) transcription by actinomycin D or by silencing Pol I catalytic subunit, RPA194. We show that CRM1 nucleolar localization is dependent on its activity and the expression of NMD3, whereas NMD3 nucleolar localization is independent of CRM1. This suggests that NMD3 provides nucleolar tethering of CRM1. While inhibition of CRM1 by leptomycin B inhibited processing of 28S ribosomal (r) RNA, depletion of NMD3 did not, suggesting that their effects on 28S rRNA processing are distinct. Markedly, depletion of NMD3 and inhibition of CRM1 reduced the rate of pre-47S rRNA synthesis. However, their inactivation did not lead to nucleolar disintegration, a hallmark of Pol I transcription stress, suggesting that they do not directly regulate transcription. These results indicate that CRM1 and NMD3 have complex functions in pathways that couple rRNA synthetic and processing engines and that the rRNA synthesis rate may be adjusted according to proficiency in rRNA processing and export.

Authors+Show Affiliations

Department of Radiation Oncology and Molecular Radiation Sciences and Sidney Kimmel Comprehensive Cancer Center; Johns Hopkins University School of Medicine; Baltimore, MD USA; Molecular Cancer Biology Program; University of Helsinki; Helsinki, Finland.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

23782956

Citation

Bai, Baoyan, et al. "CRM1 and Its Ribosome Export Adaptor NMD3 Localize to the Nucleolus and Affect rRNA Synthesis." Nucleus (Austin, Tex.), vol. 4, no. 4, 2013, pp. 315-25.
Bai B, Moore HM, Laiho M. CRM1 and its ribosome export adaptor NMD3 localize to the nucleolus and affect rRNA synthesis. Nucleus. 2013;4(4):315-25.
Bai, B., Moore, H. M., & Laiho, M. (2013). CRM1 and its ribosome export adaptor NMD3 localize to the nucleolus and affect rRNA synthesis. Nucleus (Austin, Tex.), 4(4), pp. 315-25. doi:10.4161/nucl.25342.
Bai B, Moore HM, Laiho M. CRM1 and Its Ribosome Export Adaptor NMD3 Localize to the Nucleolus and Affect rRNA Synthesis. Nucleus. 2013;4(4):315-25. PubMed PMID: 23782956.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - CRM1 and its ribosome export adaptor NMD3 localize to the nucleolus and affect rRNA synthesis. AU - Bai,Baoyan, AU - Moore,Henna M, AU - Laiho,Marikki, Y1 - 2013/06/12/ PY - 2013/6/21/entrez PY - 2013/6/21/pubmed PY - 2014/10/25/medline KW - biogenesis KW - export KW - nucleolus KW - rRNA synthesis KW - transcription SP - 315 EP - 25 JF - Nucleus (Austin, Tex.) JO - Nucleus VL - 4 IS - 4 N2 - CRM1 is an export factor that together with its adaptor NMD3 transports numerous cargo molecules from the nucleus to cytoplasm through the nuclear pore. Previous studies have suggested that CRM1 and NMD3 are detected in the nucleolus. However, their localization with subnucleolar domains or participation in the activities of the nucleolus are unclear. We demonstrate here biochemically and using imaging analyses that CRM1 and NMD3 co-localize with nucleolar marker proteins in the nucleolus. In particular, their nucleolar localization is markedly increased by inhibition of RNA polymerase I (Pol I) transcription by actinomycin D or by silencing Pol I catalytic subunit, RPA194. We show that CRM1 nucleolar localization is dependent on its activity and the expression of NMD3, whereas NMD3 nucleolar localization is independent of CRM1. This suggests that NMD3 provides nucleolar tethering of CRM1. While inhibition of CRM1 by leptomycin B inhibited processing of 28S ribosomal (r) RNA, depletion of NMD3 did not, suggesting that their effects on 28S rRNA processing are distinct. Markedly, depletion of NMD3 and inhibition of CRM1 reduced the rate of pre-47S rRNA synthesis. However, their inactivation did not lead to nucleolar disintegration, a hallmark of Pol I transcription stress, suggesting that they do not directly regulate transcription. These results indicate that CRM1 and NMD3 have complex functions in pathways that couple rRNA synthetic and processing engines and that the rRNA synthesis rate may be adjusted according to proficiency in rRNA processing and export. SN - 1949-1042 UR - https://www.unboundmedicine.com/medline/citation/23782956/CRM1_and_its_ribosome_export_adaptor_NMD3_localize_to_the_nucleolus_and_affect_rRNA_synthesis_ L2 - http://www.tandfonline.com/doi/full/10.4161/nucl.25342 DB - PRIME DP - Unbound Medicine ER -