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

• Published in: Biochemical and biophysical research communications 2005-05, Vol.330 (3), p.746-754
• Main Authors: Kim, Young-Eui, Kim, Dong-Yeon, Lee, Jang-Mi, Kim, Seong-Tae, Han, Tae-Hee, Ahn, Jin-Hyun
• Format: Article
• Language: English
• Subjects: C/EBPβ; Coiled-coil domain; Differentiation; Localization; Oligomerization; Oncogenesis; PML; PML-RARα; SUMO modification; Transactivation
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2005.03.052

Homo-oligomerization via a coiled-coil (C-C) domain has been shown to be necessary for the promyelocytic leukemia (PML)-retinoic acid receptor-α (RARα) fusion protein to acquire oncogenic potential in acute promyelocytic leukemia. We show here that PML(ΔC-C)-RARα, 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 ΔC-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 ΔC-C mutant completely lost the inhibitory effect on retinoic acid (RA)-mediated transactivation. Furthermore, the expression of CD14 in U937 cells expressing the ΔC-C mutant in response to vitamin D3 was markedly higher than in cells expressing PML-RARα. However, the RA-mediated induction of C/EBPβ in cells expressing the ΔC-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-RARα.