Requirement of the coiled-coil domain of PML-RARalpha oncoprotein for localization, sumoylation, and inhibition of monocyte differentiation.

Homo-oligomerization via a coiled-coil (C-C) domain has been shown to be necessary for the promyelocytic leukemia (PML)-retinoic acid receptor-alpha (RARalpha) fusion protein to acquire oncogenic potential in acute promyelocytic leukemia. We show here that PML(DeltaC-C)-RARalpha, which contains a deletion in its C-C domain, is neither localized as characteristic microspeckles nor ...
modified by small ubiquitin-like modifiers (SUMO). The absence of sumoylation of the DeltaC-C mutant was due to the lack of binding to Ubc9, a SUMO conjugation enzyme. The integrity of RING finger domain was also needed for both sumoylation and microspeckle formation. In GAL4-DNA tethering assays, the DeltaC-C mutant completely lost the inhibitory effect on retinoic acid (RA)-mediated transactivation. Furthermore, the expression of CD14 in U937 cells expressing the DeltaC-C mutant in response to vitamin D3 was markedly higher than in cells expressing PML-RARalpha. However, the RA-mediated induction of C/EBPbeta in cells expressing the DeltaC-C mutant was comparable to that of control cells. Thus, our results suggest that the C-C domain-associated functions of sumoylation, localization as microspeckles, and the inhibition of monocyte differentiation all contribute to the oncogenic activity of PML-RARalpha.
Mesh Terms:
Active Transport, Cell Nucleus, Animals, CCAAT-Enhancer-Binding Protein-beta, Cell Differentiation, Cell Line, Cell Nucleus, Gene Expression Regulation, Humans, Monocytes, Mutation, Neoplasm Proteins, Oncogene Proteins, Fusion, Protein Binding, Protein Structure, Quaternary, Protein Structure, Tertiary, SUMO-1 Protein, Tretinoin, Ubiquitin-Conjugating Enzymes
Biochem. Biophys. Res. Commun.
Date: May. 13, 2005
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