Comparative ultrastructure of CRM1-Nucleolar bodies (CNoBs), Intranucleolar bodies (INBs) and hybrid PML/p62 bodies uncovers new facets of nuclear body dynamic and diversity

In order to gain insights on the nuclear organization in mammalian cells, we characterized ultrastructurally nuclear bodies (NBs) previously described as fluorescent foci. Using high resolution immunoelectron microscopy (I-EM), we provide evidence that CNoBs (CRM1-Nucleolar bodies) and INBs (Intranu...

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Bibliographic Details
Published in:Nucleus (Austin, Tex.) Tex.), 2015, Vol.6 (4), p.326-338
Main Authors: Souquere, Sylvie, Weil, Dominique, Pierron, Gérard
Format: Article
Language:English
Subjects:
Active Transport, Cell Nucleus
Cell Nucleolus - ultrastructure
Chromatin - chemistry
Chromatin - genetics
CNoB
Exportin 1 Protein
Fatty Acids, Unsaturated - metabolism
HeLa Cells
Humans
immunoelectron microscopy
INB
Intranuclear Inclusion Bodies - genetics
Intranuclear Inclusion Bodies - ultrastructure
Karyopherins - genetics
Karyopherins - ultrastructure
Life Sciences
nuclear bodies
nuclear organization
nucleolus
p62/SQSTM1
PML bodies
Receptors, Cytoplasmic and Nuclear - genetics
Receptors, Cytoplasmic and Nuclear - ultrastructure
Research Paper
SUMO
SUMO-1 Protein - genetics
SUMO-1 Protein - metabolism
ubiquitin
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Summary:In order to gain insights on the nuclear organization in mammalian cells, we characterized ultrastructurally nuclear bodies (NBs) previously described as fluorescent foci. Using high resolution immunoelectron microscopy (I-EM), we provide evidence that CNoBs (CRM1-Nucleolar bodies) and INBs (Intranucleolar bodies) are distinct genuine nucleolar structures in untreated HeLa cells. INBs are fibrillar and concentrate the post-translational modifiers SUMO1 and SUMO-2/3 as strongly as PML bodies. In contrast, the smallest CRM1-labeled CNoBs are vitreous, preferentially located at the periphery of the nucleolus and, intricately linked to the chromatin network. Upon blockage of the CRM1-dependent nuclear export by leptomycin B (LMB), CNoBs disappear while p62/SQSTM1-containing fibrillar nuclear bodies are induced. These p62 bodies are enriched in ubiquitinated proteins. They progressively associate with PML bodies to form hybrid bodies of which PML decorates the periphery while p62/SQSTM1 is centrally-located. Our study is expanding the repertoire of nuclear bodies; revealing a previously unrecognized composite nucleolar landscape and a new mode of interactions between ubiquitous (PML) and stress-induced (p62) nuclear bodies, resulting in the formation of hybrid bodies.
ISSN:1949-1034
1949-1042
DOI:10.1080/19491034.2015.1082695