Proliferation of primitive myeloid progenitors can be reversibly induced by XXXX .

@entity1 @entity19 @entity30995 @entity3403 @entity2800 @entity2280 @entity803
Recent studies show that several Hox transcription factors are important for regulation of proliferation and differentiation in hematopoiesis. Among these is H0XA10, which is selectively expressed at high levels in the most primitive subpopulation of @entity1 @entity2280 (+) bone marrow cells. When overexpressed, H0XA10 increases the proliferation of early progenitor cells and can lead to the development of @entity2800 . To study the effects of H0XA10 on primitive hematopoietic progenitors in more detail, @entity19 were generated with regulatable H0XA10 expression. The transgenic @entity19 model, referred to as tetO- @entity30995 , contains the H0XA10 gene controlled by a @entity803 -responsive element and a minimal promoter. Thus, the expression of H0XA10 is inducible and reversible depending on the absence or presence of @entity803 or its analog, @entity3403 . A retroviral vector containing the @entity803 transactivator gene (tTA) was used to induce expression of the H0XA10 gene in bone marrow cells from the @entity19 . Reverse transcription-polymerase chain reaction analysis confirmed regulatable H0XA10 expression in several transgenic lines. H0XA10 induction led to the formation of hematopoietic colonies containing blastlike cells and megakaryocytes. Moreover, the induction of H0XA10 resulted in significant proliferative advantage of primitive hematopoietic progenitors (spleen colony-forming units [CFU-S(12)]), which was reversible on withdrawal of induction. Activation of H0XA10 expression in tet0-H0XA10 @entity19 will therefore govern proliferation of primitive myeloid progenitors in a regulated fashion. This novel animal model can be used to identify the target genes of @entity30995 and better clarify the specific role of @entity30995 in normal and malignant hematopoiesis.
