Tif1γ regulates the TGF-β1 receptor and promotes physiological aging of hematopoietic stem cells.
The hematopoietic system declines with age. Myeloid-biased differentiation and increased incidence of myeloid malignancies feature aging of hematopoietic stem cells (HSCs), but the mechanisms involved remain uncertain. Here, we report that 4-mo-old mice deleted for transcription intermediary factor 1γ (Tif1γ) in HSCs developed an accelerated aging phenotype. To reinforce this result, we also show that Tif1γ is down-regulated in HSCs during aging in 20-mo-old wild-type mice. We established that Tif1γ controls TGF-β1 receptor (Tgfbr1) turnover. Compared with young HSCs, Tif1γ(-/-) and old HSCs are more sensitive to TGF-β signaling. Importantly, we identified two populations of HSCs specifical…
A role for miR-142-3p in colony-stimulating factor 1-induced monocyte differentiation into macrophages
AbstractThe differentiation of human peripheral blood monocytes into macrophages can be reproduced ex vivo by culturing the cells in the presence of colony-stimulating factor 1 (CSF1). Using microarray profiling to explore the role of microRNAs (miRNAs), we identified a dramatic decrease in the expression of the hematopoietic specific miR-142-3p. Up- and down-regulation of this miRNA in primary human monocytes altered CSF1-induced differentiation of monocytes, as demonstrated by changes in the expression of the cell surface markers CD16 and CD163. One of the genes whose expression is repressed by miR-142-3p encodes the transcription factor Early Growth Response 2 (Egr2). In turn, Egr2 assoc…
Crosstalk between leukemia-associated proteins MOZ and MLL regulates HOX gene expression in human cord blood CD34+ cells
MOZ and MLL, encoding a histone acetyltransferase (HAT) and a histone methyltransferase, respectively, are targets for recurrent chromosomal translocations found in acute myeloblastic or lymphoblastic leukemia. In MOZ (MOnocytic leukemia Zinc-finger protein)/CBP- or mixed lineage leukemia (MLL)-rearranged leukemias, abnormal levels of HOX transcription factors have been found to be critical for leukemogenesis. We show that MOZ and MLL cooperate to regulate these key genes in human cord blood CD34+ cells. These chromatin-modifying enzymes interact, colocalize and functionally cooperate, and both are recruited to multiple HOX promoters. We also found that WDR5, an adaptor protein essential fo…
Transcription intermediary factor 1γ is a tumor suppressor in mouse and human chronic myelomonocytic leukemia.
Transcription intermediary factor 1γ (TIF1γ) was suggested to play a role in erythropoiesis. However, how TIF1γ regulates the development of different blood cell lineages and whether TIF1γ is involved in human hematological malignancies remain to be determined. Here we have shown that TIF1γ was a tumor suppressor in mouse and human chronic myelomonocytic leukemia (CMML). Loss of Tif1g in mouse HSCs favored the expansion of the granulo-monocytic progenitor compartment. Furthermore, Tif1g deletion induced the age-dependent appearance of a cell-autonomous myeloproliferative disorder in mice that recapitulated essential characteristics of human CMML. TIF1γ was almost undetectable in leukemic ce…
The Histone Acetyl-Transferase MOZ Cooperates with the Histone Methyl-Transferase MLL to Regulate HOX Gene Expression in Human Hematopoietic Stem Cells
Abstract MOZ (MOnocytic leukaemia Zinc finger protein) (also called MYST3 or KAT6A) is a member of the MYST family of HATs which likely acetylate H4K16. The MLL (MixedLineageLeukemia) gene is a frequent target for recurrent chromosomal translocations found in AML and ALL. MLL (KMT2A) is a methyl-transferase targeting H3K4. It was shown that MOZ/CBP leukemia, as observed in MLL-rearranged leukemias, harbors abnormal levels of homeobox (HOX) genes expression. HOX transcription factors have a crucial function in hematopoiesis regulation. In addition, HOXA5, HOXA7, and HOXA9 are often considered to be pivotal HOX genes for MLL transformation, constituting downstream targets of MLL. In our study…
Symplekin, a polyadenylation factor, prevents MOZ and MLL activity on HOXA9 in hematopoietic cells
International audience; MOZ and MLL encoding a histone acetyltransferase and a histone methyltransferase, respectively, are targets for recurrent chromosomal translocations found in acute myeloblastic or lymphoblastic leukemia. We have previously shown that MOZ and MLL cooperate to activate HOXA9 gene expression in hematopoietic stem/progenitors cells. To dissect the mechanism of action of this complex, we decided to identify new proteins interacting with MOZ. We found that the scaffold protein Symplekin that supports the assembly of polyadenylation machinery was identified by mass spectrometry. Symplekin interacts and co-localizes with both MOZ and MLL in immature hematopoietic cells. Its …
A MiR-142-3p/EGR2 Feedback Circuitry In Human CSF-1 Driven Differentiation of Monocytes Into Macrophages
Abstract Abstract 2366 Colony-stimulating factor-1 (CSF-1 or M-CSF) triggers the differentiation of human peripheral blood monocytes into macrophages through and integrated cytokine/transcription factors circuitry. Using microarray profiling to explore the role of microRNAs (miRNAs) in this molecular circuitry, we identified the down-regulation of miR-142-3p in human macrophages obtained from CSF-1-treated monocytes. We show that miR-142-3p is a repressor of the transcription factor EGR2 (Early Growth Response 2) through direct 3'UTR interactions. Interestingly, EGR2 binds the promoter of the pre-miR-142-3p gene to negatively regulate its expression, identifying a self-regulatory feedback l…