TY - JOUR
T1 - Subcellular distribution of nuclear import-defective isoforms of the promyelocytic leukemia protein
AU - Jul-Larsen, Åsne
AU - Grudic, Amra
AU - Bjerkvig, Rolf
AU - Bøe, Stig O.
N1 - Funding Information:
The authors would like to thank Professor Roger Everett at MRC Virology unit in Glasgow, Scotland for generously providing the lentivirus vectors expressing FLAG-tagged PML. ÅJL was funded by the Norwegian Cancer Society, AG was funded by the University of Bergen and SOB was funded by the Norwegian Research Council. The work was further supported by the Cancer Gene Therapy Program funded by the Norwegian Health Department and Helse-Vest.
PY - 2010/11/21
Y1 - 2010/11/21
N2 - Background: The promyelocytic leukemia (PML) protein participates in a number of cellular processes, including transcription regulation, apoptosis, differentiation, virus defense and genome maintenance. This protein is structurally organized into a tripartite motif (TRIM) at its N-terminus, a nuclear localization signal (NLS) at its central region and a C-terminus that varies between alternatively spliced isoforms. Most PML splice variants target the nucleus where they define sub-nuclear compartments termed PML nuclear bodies (PML NBs). However, PML variants that lack the NLS are also expressed, suggesting the existence of PML isoforms with cytoplasmic functions. In the present study we expressed PML isoforms with a mutated NLS in U2OS cells to identify potential cytoplasmic compartments targeted by this protein.Results: Expression of NLS mutated PML isoforms in U2OS cells revealed that PML I targets early endosomes, PML II targets the inner nuclear membrane (partially due to an extra NLS at its C-terminus), and PML III, IV and V target late endosomes/lysosomes. Clustering of PML at all of these subcellular locations depended on a functional TRIM domain.Conclusions: This study demonstrates the capacity of PML to form macromolecular protein assemblies at several different subcellular sites. Further, it emphasizes a role of the variable C-terminus in subcellular target selection and a general role of the N-terminal TRIM domain in promoting protein clustering.
AB - Background: The promyelocytic leukemia (PML) protein participates in a number of cellular processes, including transcription regulation, apoptosis, differentiation, virus defense and genome maintenance. This protein is structurally organized into a tripartite motif (TRIM) at its N-terminus, a nuclear localization signal (NLS) at its central region and a C-terminus that varies between alternatively spliced isoforms. Most PML splice variants target the nucleus where they define sub-nuclear compartments termed PML nuclear bodies (PML NBs). However, PML variants that lack the NLS are also expressed, suggesting the existence of PML isoforms with cytoplasmic functions. In the present study we expressed PML isoforms with a mutated NLS in U2OS cells to identify potential cytoplasmic compartments targeted by this protein.Results: Expression of NLS mutated PML isoforms in U2OS cells revealed that PML I targets early endosomes, PML II targets the inner nuclear membrane (partially due to an extra NLS at its C-terminus), and PML III, IV and V target late endosomes/lysosomes. Clustering of PML at all of these subcellular locations depended on a functional TRIM domain.Conclusions: This study demonstrates the capacity of PML to form macromolecular protein assemblies at several different subcellular sites. Further, it emphasizes a role of the variable C-terminus in subcellular target selection and a general role of the N-terminal TRIM domain in promoting protein clustering.
UR - http://www.scopus.com/inward/record.url?scp=78449241862&partnerID=8YFLogxK
U2 - 10.1186/1471-2199-11-89
DO - 10.1186/1471-2199-11-89
M3 - Article
C2 - 21092142
AN - SCOPUS:78449241862
SN - 1471-2199
VL - 11
JO - BMC Molecular Biology
JF - BMC Molecular Biology
M1 - 89
ER -