TIS21/(BTG2) negatively regulates estradiol-stimulated expansion of hematopoietic stem cells by derepressing Akt phosphorylation and inhibiting mTOR signal transduction.
Stem Cells
; 26(9): 2339-48, 2008 Sep.
Article
em En
| MEDLINE
| ID: mdl-18556508
ABSTRACT
It has been known that 12-O-tetradecanoyl phorbol-13-acetate-inducible sequence 21 (TIS21), ortholog of human B-cell translocation gene 2, regulates expansions of stage-specific thymocytes and hematopoietic progenitors. In the present study, lineage-negative (Lin(-))/stem cell antigen-1-positive (Sca-1+)/c-Kit+ (LSK) cell content was significantly elevated in bone marrow (BM) of TIS21-knockout (TIS21(-/-)) female mice, suggesting 17beta-estradiol (E(2))-regulated progenitor expansion. E(2) induced DNA synthesis and cell proliferation of mouse embryonic fibroblasts (MEFs) isolated from TIS21(-/-) mice, but not wild type (WT). In contrast to WT, E(2) failed to activate protein kinase B (Akt) in the TIS21(-/-) MEFs, independent of extracellular signal-regulated kinase 1/2 (Erk1/2) activation. Despite attenuation of Akt activation, mammalian target of rapamycin (mTOR) was constitutively activated in the TIS21(-/-) MEFs. Furthermore, mitogen-activated protein kinase 1/2 inhibitor or knockdown of Erk1 could restore activation of Akt and downregulate mTOR. Immunoprecipitation showed Akt preferentially bound to phosphorylated Erk1/2 (p-Erk1/2) in TIS21(-/-) cells, but reconstitution of TIS21 inhibited their interaction. E(2)-injected TIS21(-/-) male mice also increased LSK cells in BM. Taken together, expansion of hematopoietic progenitors in TIS21(-/-) female mice might be through inhibition of Akt activation, and constitutive activation of mTOR via preferential binding of TIS21 to E(2)-induced p-Erk1/2, compared with that of Akt. Our results suggest that TIS21 plays a pivotal role in maintaining the hematopoietic stem cell compartment and hematopoiesis.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Células-Tronco Hematopoéticas
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Proteínas de Transporte
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Genes Supressores de Tumor
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Fosfotransferases (Aceptor do Grupo Álcool)
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Proteínas Imediatamente Precoces
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Estradiol
Limite:
Animals
Idioma:
En
Ano de publicação:
2008
Tipo de documento:
Article