The nucleolar protein nucleophosmin is essential for autophagy induced by inhibiting Pol I transcription

Various cellular stresses activate autophagy, which is involved in lysosomal degradation of cytoplasmic materials for maintaining nutrient homeostasis and eliminating harmful components. Here, we show that RNA polymerase I (Pol I) transcription inhibition induces nucleolar disruption and autophagy....

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Bibliographic Details
Published in:Scientific reports 2015-03, Vol.5 (1), p.8903-8903, Article 8903
Main Authors: Katagiri, Naohiro, Kuroda, Takao, Kishimoto, Hiroyuki, Hayashi, Yuki, Kumazawa, Takuya, Kimura, Keiji
Format: Article
Language:English
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Autophagy
Autophagy - genetics
Cell Nucleolus - genetics
DNA-directed RNA polymerase
Homeostasis
Humanities and Social Sciences
Humans
Lysosomes
MCF-7 Cells
multidisciplinary
Nuclear Proteins - antagonists & inhibitors
Nuclear Proteins - genetics
Nucleoli
Nucleolus Organizer Region - genetics
Nutrients
Phagocytosis
RNA polymerase
RNA Polymerase I - antagonists & inhibitors
RNA Polymerase I - genetics
RNA, Small Interfering
Science
siRNA
Transcription
Transcription, Genetic
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Summary:Various cellular stresses activate autophagy, which is involved in lysosomal degradation of cytoplasmic materials for maintaining nutrient homeostasis and eliminating harmful components. Here, we show that RNA polymerase I (Pol I) transcription inhibition induces nucleolar disruption and autophagy. Treatment with autophagy inhibitors or siRNA specific for autophagy-related (ATG) proteins inhibited autophagy but not nucleolar disruption induced by Pol I transcription inhibition, which suggested that nucleolar disruption was upstream of autophagy. Furthermore, treatment with siRNA specific for nucleolar protein nucleophosmin (NPM) inhibited this type of autophagy. This showed that NPM was involved in autophagy when the nucleolus was disrupted by Pol I inhibition. In contrast, NPM was not required for canonical autophagy induced by nutrient starvation, as it was not accompanied by nucleolar disruption. Thus, our results revealed that, in addition to canonical autophagy, there may be NPM-dependent autophagy associated with nucleolar disruption.
ISSN:2045-2322
2045-2322
DOI:10.1038/srep08903