Open AccessThe SCL/TAL 1 Transcription Factor Represses the Stress Protein DD i T 4/ REDD 1 in Human Hematopoietic Stem/Progenitor Cells
Author(s) -
Benyoucef Aissa,
Calvo Julien,
Renou Laurent,
Arcangeli MarieLaure,
van den Heuvel Anita,
Amsellem Sophie,
Mehrpour Maryam,
Larghero Jerome,
Soler Eric,
Naguibneva Irina,
Pflumio Francoise
Publication year - 2015
Publication title -
stem cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.159
H-Index - 229
eISSN - 1549-4918
pISSN - 1066-5099
DOI - 10.1002/stem.2028
Subject(s) - biology , haematopoiesis , stem cell , progenitor cell , transcription factor , microbiology and biotechnology , genetics , gene
Hematopoietic stem/progenitor cells (HSPCs) are regulated through numerous molecular mechanisms that have not been interconnected. The transcription factor stem cell leukemia/T‐cell acute leukemia 1 (TAL1) controls human HSPC but its mechanism of action is not clarified. In this study, we show that knockdown (KD) or short‐term conditional over‐expression (OE) of TAL1 in human HSPC ex vivo, respectively, blocks and maintains hematopoietic potentials, affecting proliferation of human HSPC. Comparative gene expression analyses of TAL1/KD and TAL1/OE human HSPC revealed modifications of cell cycle regulators as well as previously described TAL1 target genes. Interestingly an inverse correlation between TAL1 and DNA damage‐induced transcript 4 (DDiT4/REDD1), an inhibitor of the mammalian target of rapamycin (mTOR) pathway, is uncovered. Low phosphorylation levels of mTOR target proteins in TAL1/KD HSPC confirmed an interplay between mTOR pathway and TAL1 in correlation with TAL1‐mediated effects of HSPC proliferation. Finally chromatin immunoprecipitation experiments performed in human HSPC showed that DDiT4 is a direct TAL1 target gene. Functional analyses showed that TAL1 represses DDiT4 expression in HSPCs. These results pinpoint DDiT4/REDD1 as a novel target gene regulated by TAL1 in human HSPC and establish for the first time a link between TAL1 and the mTOR pathway in human early hematopoietic cells. S tem C ells 2015;33:2268–2279