Advanced

Phosphorylation of Serine 248 of C/EBP alpha Is Dispensable for Myelopoiesis but Its Disruption Leads to a Low Penetrant Myeloid Disorder with Long Latency

Hasemann, Marie S.; Schuster, Mikkel B.; Frank, Anne-Katrine; Theilgaard-Moench, Kim LU ; Pedersen, Thomas A.; Nerlov, Claus and Porse, Bo T. (2012) In PLoS ONE 7(6).
Abstract
Background: Transcription factors play a key role in lineage commitment and differentiation of stem cells into distinct mature cells. In hematopoiesis, they regulate lineage-specific gene expression in a stage-specific manner through various physical and functional interactions with regulatory proteins that are simultanously recruited and activated to ensure timely gene expression. The transcription factor CCAAT/enhancer binding protein alpha (C/EBP alpha) is such a factor and is essential for the development of granulocytic/monocytic cells. The activity of C/EBP alpha is regulated on several levels including gene expression, alternative translation, protein interactions and posttranslational modifications, such as phosphorylation. In... (More)
Background: Transcription factors play a key role in lineage commitment and differentiation of stem cells into distinct mature cells. In hematopoiesis, they regulate lineage-specific gene expression in a stage-specific manner through various physical and functional interactions with regulatory proteins that are simultanously recruited and activated to ensure timely gene expression. The transcription factor CCAAT/enhancer binding protein alpha (C/EBP alpha) is such a factor and is essential for the development of granulocytic/monocytic cells. The activity of C/EBP alpha is regulated on several levels including gene expression, alternative translation, protein interactions and posttranslational modifications, such as phosphorylation. In particular, the phosphorylation of serine 248 of the transactivation domain has been shown to be of crucial importance for granulocytic differentiation of 32Dcl3 cells in vitro. Methodology/Principal Findings: Here, we use mouse genetics to investigate the significance of C/EBP alpha serine 248 in vivo through the construction and analysis of Cebpa(S248A/S248A) knock-in mice. Surprisingly, 8-week old Cebpa(S248A/S248A) mice display normal steady-state hematopoiesis including unaltered development of mature myeloid cells. However, over time some of the animals develop a hematopoietic disorder with accumulation of multipotent, megakaryocytic and erythroid progenitor cells and a mild impairment of differentiation along the granulocytic-monocytic lineage. Furthermore, BM cells from Cebpa(S248A/S248A) animals display a competitive advantage compared to wild type cells in a transplantation assay. Conclusions/Significance: Taken together, our data shows that the substitution of C/EBP alpha serine 248 to alanine favors the selection of the megakaryocytic/erythroid lineage over the monocytic/granulocytic compartment in old mice and suggests that S248 phosphorylation may be required to maintain proper hematopoietic homeostasis in response to changes in the wiring of cellular signalling networks. More broadly, the marked differences between the phenotype of the S248A variant in vivo and in vitro highlight the need to exert caution when extending in vitro phenotypes to the more appropriate in vivo context. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
PLoS ONE
volume
7
issue
6
publisher
Public Library of Science
external identifiers
  • wos:000305336800058
  • scopus:84862015400
ISSN
1932-6203
DOI
10.1371/journal.pone.0038841
language
English
LU publication?
yes
id
c5d500e6-4d20-402e-a299-c8a86b473bfa (old id 2890535)
date added to LUP
2012-08-01 09:40:08
date last changed
2017-01-01 06:06:47
@article{c5d500e6-4d20-402e-a299-c8a86b473bfa,
  abstract     = {Background: Transcription factors play a key role in lineage commitment and differentiation of stem cells into distinct mature cells. In hematopoiesis, they regulate lineage-specific gene expression in a stage-specific manner through various physical and functional interactions with regulatory proteins that are simultanously recruited and activated to ensure timely gene expression. The transcription factor CCAAT/enhancer binding protein alpha (C/EBP alpha) is such a factor and is essential for the development of granulocytic/monocytic cells. The activity of C/EBP alpha is regulated on several levels including gene expression, alternative translation, protein interactions and posttranslational modifications, such as phosphorylation. In particular, the phosphorylation of serine 248 of the transactivation domain has been shown to be of crucial importance for granulocytic differentiation of 32Dcl3 cells in vitro. Methodology/Principal Findings: Here, we use mouse genetics to investigate the significance of C/EBP alpha serine 248 in vivo through the construction and analysis of Cebpa(S248A/S248A) knock-in mice. Surprisingly, 8-week old Cebpa(S248A/S248A) mice display normal steady-state hematopoiesis including unaltered development of mature myeloid cells. However, over time some of the animals develop a hematopoietic disorder with accumulation of multipotent, megakaryocytic and erythroid progenitor cells and a mild impairment of differentiation along the granulocytic-monocytic lineage. Furthermore, BM cells from Cebpa(S248A/S248A) animals display a competitive advantage compared to wild type cells in a transplantation assay. Conclusions/Significance: Taken together, our data shows that the substitution of C/EBP alpha serine 248 to alanine favors the selection of the megakaryocytic/erythroid lineage over the monocytic/granulocytic compartment in old mice and suggests that S248 phosphorylation may be required to maintain proper hematopoietic homeostasis in response to changes in the wiring of cellular signalling networks. More broadly, the marked differences between the phenotype of the S248A variant in vivo and in vitro highlight the need to exert caution when extending in vitro phenotypes to the more appropriate in vivo context.},
  author       = {Hasemann, Marie S. and Schuster, Mikkel B. and Frank, Anne-Katrine and Theilgaard-Moench, Kim and Pedersen, Thomas A. and Nerlov, Claus and Porse, Bo T.},
  issn         = {1932-6203},
  language     = {eng},
  number       = {6},
  publisher    = {Public Library of Science},
  series       = {PLoS ONE},
  title        = {Phosphorylation of Serine 248 of C/EBP alpha Is Dispensable for Myelopoiesis but Its Disruption Leads to a Low Penetrant Myeloid Disorder with Long Latency},
  url          = {http://dx.doi.org/10.1371/journal.pone.0038841},
  volume       = {7},
  year         = {2012},
}