Nucleic Acids Research Advance Access originally published online on September 28, 2007
Nucleic Acids Research 2007 35(19):6571-6587; doi:10.1093/nar/gkm753
Nucleic Acids Research, 2007, Vol. 35, No. 19 6571-6587
© 2007 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Molecular Biology |
Subcellular distribution of human RDM1 protein isoforms and their nucleolar accumulation in response to heat shock and proteotoxic stress
1International Agency for Research on Cancer (IARC), 150 Cours Albert Thomas, 69372 Lyon, France, 2Department of Human Genetics, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima, Japan 734-8553, 3Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA, 4Laboratoire de Biologie Moléculaire des Eucaryotes, LBME-CNRS UMR 5099 - IFR 109, Université Paul Sabatier, 118, Route de Narbonne, 31062 Toulouse, France and 5Institute for Molecular Radiobiology, GSF, Ingolstaedter Landstrasse 1, D-85764 Neuherberg-Munich, Germany
*To whom correspondence should be addressed. Tel: +33 4 72 73 83 93; Fax: +33 4 72 73 83 22; Email: vandyck{at}iarc.fr or Vandyckeric{at}hotmail.com
Received June 13, 2007. Revised August 28, 2007. Accepted September 11, 2007.
Accession No. EF488473-EF488482
The RDM1 gene encodes a RNA recognition motif (RRM)-containing protein involved in the cellular response to the anti-cancer drug cisplatin in vertebrates. We previously reported a cDNA encoding the full-length human RDM1 protein. Here, we describe the identification of 11 human cDNAs encoding RDM1 protein isoforms. This repertoire is generated by alternative pre-mRNA splicing and differential usage of two translational start sites, resulting in proteins with long or short N-terminus and a great diversity in the exonic composition of their C-terminus. By using tagged proteins and fluorescent microscopy, we examined the subcellular distribution of full-length RDM1 (renamed RDM1
), and other RDM1 isoforms. We show that RDM1 undergoes subcellular redistribution and nucleolar accumulation in response to proteotoxic stress and mild heat shock. In unstressed cells, the long N-terminal isoforms displayed distinct subcellular distribution patterns, ranging from a predominantly cytoplasmic to almost exclusive nuclear localization, suggesting functional differences among the RDM1 proteins. However, all isoforms underwent stress-induced nucleolar accumulation. We identified nuclear and nucleolar localization determinants as well as domains conferring cytoplasmic retention to the RDM1 proteins. Finally, RDM1 null chicken DT40 cells displayed an increased sensitivity to heat shock, compared to wild-type (wt) cells, suggesting a function for RDM1 in the heat-shock response.
Present address: Lydia Messaoudi, Institut de Cancérologie Gustave Roussy, Villejuif, France Yun-Gui Yang, Cancer Research UK, London Research Institute, Clare Hall Laboratories, UK Gonghong Yan, Department of Pharmacology, University of Pittsburgh School of Medicine, USA Minoru Takata, Radiation Biology Center, Kyoto University, Kyoto, Japan