Stabilization of PML nuclear localization by conjugation and oligomerization of SUMO-3.
The PML gene of acute promyelocytic leukemia (APL) encodes a cell-growth and tumor suppressor. PML localizes to discrete nuclear bodies (NBs) that are disrupted in APL cells, resulting from a reciprocal chromosome translocation t (15;17). Here we show that the nuclear localization of PML is also regulated by SUMO-3, one of the three recently identified SUMO isoforms in human cells. SUMO-3 bears similar subcellular distribution to those of SUMO-1 and -2 in the interphase nuclear body, which is colocalized with PML protein. However, both SUMO-2 and -3 are also localized to nucleoli, a region lacking SUMO-1. Immunoprecipitated PML protein bears SUMO-3 moiety in a covalently modified form, supporting the notion that PML is conjugated by SUMO-3. To determine the functional relevance of SUMO-3 conjugation on PML molecular dynamics, we suppressed SUMO-3 protein expression using a siRNA-mediated approach. Depletion of SUMO-3 markedly reduced the number of PML-containing NBa and their integrity, which is rescued by exogenous expression of SUMO-3 but not SUMO-1 or SUMO-2. The specific requirement of SUMO-3 for PML nuclear localization is validated by expression of SUMO-3 conjugation defective mutant. Moreover, we demonstrate that oligomerization of SUMO-3 is required for PML retention in the nucleus. Taken together, our studies provide first line of evidence showing that SUMO-3 is essential for PML localization and offer novel insight into the pathobiochemistry of APL.
Fu
Chuanhai
C
School of Life Sciences, University of Science and Technology of China, Hefei 230027, China.
Ahmed
Kashif
K
Ding
Husheng
H
Ding
Xia
X
Lan
Jianping
J
Yang
Zhihong
Z
Miao
Yong
Y
Zhu
Yuanyuan
Y
Shi
Yunyu
Y
Zhu
Jingde
J
Huang
He
H
Yao
Xuebiao
X
D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D045586:Intranuclear Inclusion Bodies / Q000737:chemistry / Q000378:metabolism*; D015473:Leukemia, Promyelocytic, Acute / Q000378:metabolism; D018613:Microscopy, Confocal; D016297:Mutagenesis, Site-Directed; D009363:Neoplasm Proteins / Q000737:chemistry / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D000071156:Promyelocytic Leukemia Protein; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D034741:RNA, Small Interfering; D025842:SUMO-1 Protein / Q000737:chemistry / Q000378:metabolism; D025841:Small Ubiquitin-Related Modifier Proteins / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000378:metabolism*
D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D000071156:Promyelocytic Leukemia Protein; D020033:Protein Isoforms; D034741:RNA, Small Interfering; D025842:SUMO-1 Protein; C117909:SUMO2 protein, human; D025841:Small Ubiquitin-Related Modifier Proteins; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C070576:PML protein, human