Mechanism of extended self renewal in mature differentiated macrophages – ReNEW
Self-renewal of mature macrophages
In metazoan organisms terminal differentiation is typically tightly linked to cell cycle withdrawal, whereas the undifferentiated state of pluripotent stem cells is associated with unlimited self-renewal. Our group recently discovered that combined deficiency for the transcription factors MafB and c-Maf enables extended long-term expansion of mature macrophages in culture without loss of differentiated phenotype and function. (Science 326:867 (2009)).
Self-renewal of mature macrophages
Our observation that MafB/c-MafB deficient macrophages show extended self-renwal,<br />without malignant transformation, loss of differentiated function or stem cell intermediates<br />represents a novel concept as self-renewal normally is a defining characteristic of stem cells.<br />We want to decipher the underlyin molecular mechanisms that permit continuous selfrenewal<br />in a functionally differentiated cell. This would be of general interest for fundamental<br />biology, with far reaching implication for stem cell and tumor biology. Identification of the key<br />principles of differentiated self-renewal that may be applicable more generally to other cell<br />types beyond macrophages could be significance for regenerative medicine and drug<br />screening applications in the future.
transcriptomic, ChIP-seq, lentiviral transduction, bio-informatic analyses
Status analysis of telomeres in the self-renewal of somatic cells.
Identification and analysis of self-renewal genes.
Wide analysis of the genome specific enhancers of self-renewal (Complete, results submitted for publication). The abstract of the publication subject is presented here:
Activation of Self-Renewal Gene Network on Macrophage-Specific Enhancer Platform
Erinn L. Soucie, Ziming Weng Kaaweh Molawi, Romain Fennel, Maurizio Julien Pierre Perrin, Meryam Beniazza Jeremy Favret Nir Hacohen, J.-C. Andrau Pierre Ferrier, Patrice Dubreuil, Arend Sidow, Michael H. Sieweke
Differentiated macrophages can self-Maintain and expand by local proliferation in tissues and Can Be enabled to long-term self-renew in culture. Unlimited self-renewal is Considered a stem cell property aussi That can BE in Differentiated cells induced by iPS reprogramming full loss of the cell types impliquant Specific enhancer directory. Here we show That self-renewal of macrophages can Occur without enhancer reshuffling goal by activation of macrophage Specific poised enhancers proximal to functionally annotated genes with self-renewal activity. MOST inactivation of genes regulated macrophage Abolished self-renewal and Revealed genetic cross-regulation centered on c-Myc and KLF2. Our results indicate indication That mature macrophages can activate a network of like stem cell self-renewal genes were lineage Specific enhancer platform That allowded Maintenance of Differentiated cell identity.
Analysis of the mechanisms of action of c-Myc and Klf4 in the self-renewal (in progress).
1) Forced expression of Myc and Klf4 of macrophages in WT
2) That -Validation Myc / phrase providing macrophages phenocopy Klf4 and c-Maf MafB deficiency.
3) -Transcriptional networks Involved in Myc / Klf4 induced self-renewal and control of c-myc tumorigenicity by Klf4.
Our observation that MafB/c-MafB deficient macrophages show extended self-renwal,
without malignant transformation, loss of differentiated function or stem cell intermediates
represents a novel concept as self-renewal normally is a defining characteristic of stem cells.
We want to decipher the underlyin molecular mechanisms that permit continuous selfrenewal
in a functionally differentiated cell. This would be of general interest for fundamental
biology, with far reaching implication for stem cell and tumor biology. Identification of the key
principles of differentiated self-renewal that may be applicable more generally to other cell
types beyond macrophages could be significance for regenerative medicine and drug
screening applications in the future.
Publications originales:
Sieweke MH, Allen JE
Beyond Stem Cells : self-renewal of differentiated macrophages
Science, 22;342(6161) :1242974 (2013)
Gentek R, Molawi K, Sieweke MH
Tissue macrophage identity and self-renewal
Immunol Rev, 262(1) :56-73 (2014)
Patents:
1. Method for expanding monocytes
United States patent No. 8,574,903 B2, delivered 05.11.2013
Japon patent No. 5579442, delivered 18.07.2014
Singapore patent No.154039, delivered 15.02.2012
2. Method for generating, maintaining and expanding monocytes, and/or macrophages and/or dendritic cells in long term culture.
United States patent No. 8,691,964 B2, delivered 08.04.2014
European patent No. pub 1944361, 16.07.2008, filed 10.01.2007
3. Methods and compositions for use in preventing or treating myeloid cytopenia and related complications.
European patent No. 13305464.3-1456 : filed 09.04.2013
WO patent, No. Pub WO 2014/167018, filed 16.10.2014
4. MafB mutants and uses thereof
European patent No. 13306661.3, filed : 3.12.2013
In metazoan organisms terminal differentiation is typically tightly linked to cell cycle withdrawal, whereas the undifferentiated state of pluripotent stem cells is associated with unlimited self-renewal. Our group recently discovered that combined deficiency for the transcription factors MafB and c-Maf enables extended long-term expansion of mature macrophages in culture without loss of differentiated phenotype and function. Upon transplantation, the expanded cells are non-tumorigenic and contribute to functional macrophage populations in vivo. Our results indicate that MafB/c-MafB deficiency renders self-renewal compatible with terminal differentiation and that it is possible to amplify functional differentiated cells without malignant transformation or stem cell intermediates (Science 326:867 (2009)).
Landmark discoveries over the last few years have established that the four transcription factors Oct-4, Sox-2, KLF4 and c-Myc can reprogram differentiated cells into pluripotent stem cells (iPS) that are highly similar to embryonic stem cells. Whereas Oct-4 and Sox-2 are part of a circuit required for pluripotency, c-Myc and KLF4 are dispensable for pluripotency but have been suggested to mediate self-renewal. We observed that MafB/c-Maf deficient macrophages concomitantly up-regulate c-Myc and KLF4, which is required to sustain extended proliferation capacity. Our results suggest that pluripotency and self-renewal are two stem cell characteristics that can be mechanistically dissociated and that self-renewal may be induced in differentiated cells without induction of pluripotency, tumorigenic transformation or loss of functional differentiation. Here we want to investigate the underlying molecular mechanisms of self-renewal in differentiated cells. Using genome wide approaches we will determine the gene activity and epigenetic signatures that enable proliferation while stably maintaining differentiated gene expression through multiple cell divisions. We will in particular compare our observations to available information from embryonic stem cells to define gene networks and molecular mechanisms that enable self renewal in differentiated and pluripotent stem cells, with the objective to establish generally valid principles that could be applied to other cell types. We have developed new experimental tools of inducible gene expression and have assembled a team of experts in the relevant molecular mechanisms and genome wide approaches to address these questions.
Project coordination
Michael SIEWEKE (INSTITUT NATIONAL DE LA SANTE ET DE LA RECHERCHE MEDICALE - DELEGATION PACA)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
Partnership
CIML INSTITUT NATIONAL DE LA SANTE ET DE LA RECHERCHE MEDICALE - DELEGATION PACA
LBPG INSTITUT NATIONAL DE LA SANTE ET DE LA RECHERCHE MEDICALE - DELEGATION PACA
Help of the ANR 500,000 euros
Beginning and duration of the scientific project:
November 2011
- 48 Months
