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PLoS Genet. 2014 May 29;10(5):e1004371. doi: 10.1371/journal.pgen.1004371. eCollection 2014.

Ribosomal protein mutations induce autophagy through S6 kinase inhibition of the insulin pathway.

Author information

1
Cell Microscopy Center, Department of Cell Biology, University Medical Center Utrecht, Utrecht, The Netherlands; Department of Clinical Chemistry and Haematology, University Medical Center Utrecht, Utrecht, The Netherlands.
2
Department of Clinical Chemistry and Haematology, University Medical Center Utrecht, Utrecht, The Netherlands.
3
Hubrecht Institute, KNAW and University Medical Center Utrecht, The Netherlands.
4
U1009, Institut Gustave Roussy, Université Paris-Sud, Villejuif, France.
5
Department of Nephrology, University Medical Center Utrecht, Utrecht, The Netherlands.
6
Department of Pediatric Hematology, Immunology and Infectious Diseases, Emma Children's Hospital, Academic Medical Center (AMC), Amsterdam, The Netherlands.
7
Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, Massachusetts, United States of America; Harvard Medical School, Boston, Massachusetts, United States of America; Broad Institute, Cambridge, Massachusetts, United States of America.
8
Department of Pediatric Hematology/Oncology, University Medical Center Utrecht, Utrecht, The Netherlands.
9
AP-HP, Service d'Hématologie Biologique, Hôpital Robert Debré, Paris, France; Université Paris VII-Denis Diderot, Sorbonne Paris Cité, Paris, France; U773, CRB3, Paris, France.

Abstract

Mutations affecting the ribosome lead to several diseases known as ribosomopathies, with phenotypes that include growth defects, cytopenia, and bone marrow failure. Diamond-Blackfan anemia (DBA), for example, is a pure red cell aplasia linked to the mutation of ribosomal protein (RP) genes. Here we show the knock-down of the DBA-linked RPS19 gene induces the cellular self-digestion process of autophagy, a pathway critical for proper hematopoiesis. We also observe an increase of autophagy in cells derived from DBA patients, in CD34+ erythrocyte progenitor cells with RPS19 knock down, in the red blood cells of zebrafish embryos with RP-deficiency, and in cells from patients with Shwachman-Diamond syndrome (SDS). The loss of RPs in all these models results in a marked increase in S6 kinase phosphorylation that we find is triggered by an increase in reactive oxygen species (ROS). We show that this increase in S6 kinase phosphorylation inhibits the insulin pathway and AKT phosphorylation activity through a mechanism reminiscent of insulin resistance. While stimulating RP-deficient cells with insulin reduces autophagy, antioxidant treatment reduces S6 kinase phosphorylation, autophagy, and stabilization of the p53 tumor suppressor. Our data suggest that RP loss promotes the aberrant activation of both S6 kinase and p53 by increasing intracellular ROS levels. The deregulation of these signaling pathways is likely playing a major role in the pathophysiology of ribosomopathies.

PMID:
24875531
PMCID:
PMC4038485
DOI:
10.1371/journal.pgen.1004371
[Indexed for MEDLINE]
Free PMC Article

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