Subcellular distribution of human RDM1 protein isoforms and their nucleolar accumulation in response to heat shock and proteotoxic stress.
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 RDM1alpha), and other RDM1 isoforms. We show that RDM1alpha 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.
Messaoudi
Lydia
L
International Agency for Research on Cancer (IARC), 150 Cours Albert Thomas, 69372 Lyon, France.
Yang
Yun-Gui
YG
Kinomura
Aiko
A
Stavreva
Diana A
DA
Yan
Gonghong
G
Bortolin-Cavaillé
Marie-Line
ML
Arakawa
Hiroshi
H
Buerstedde
Jean-Marie
JM
Hainaut
Pierre
P
Cavaillé
Jérome
J
Takata
Minoru
M
Van Dyck
Eric
E
D000111:Acetylcysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002466:Cell Nucleolus / Q000737:chemistry*; D002467:Cell Nucleus / Q000737:chemistry; D002645:Chickens; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003593:Cytoplasm / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000032:analysis* / Q000737:chemistry / Q000235:genetics*; D003609:Dactinomycin / Q000494:pharmacology; D005091:Exons; D017353:Gene Deletion; D018869:Heat-Shock Response; D006801:Humans; D008969:Molecular Sequence Data; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D061988:Proteasome Inhibitors; D020033:Protein Isoforms / Q000032:analysis / Q000737:chemistry / Q000235:genetics; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
D015853:Cysteine Proteinase Inhibitors; D004268:DNA-Binding Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D061988:Proteasome Inhibitors; D020033:Protein Isoforms; C499652:RDM1 protein, human; D012333:RNA, Messenger; C067713:lactacystin; D003609:Dactinomycin; D000111:Acetylcysteine