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Hématologie

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Role of homeodomain-containing proteins in hematopoiesis Volume 6, issue 2, Mars - Avril 2000

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Homeoproteins are transcription factors involved in development and morphogenesis. These proteins are encoded by homeobox-containing genes and comprise a characteristic DNA-binding domain of 60 amino acids called homeodomain. The canonical homeodomain structure is represented by the Drosophila Antennapedia homeodomain sequence. In vertebrates, the class I of homeotic genes consists in the 39 Hox family genes which are grouped in 4 clusters, HoxA, B, C and D. A variety of other homeoprotein-coding genes of different classes have also been described. Beyond their functions in development, these genes can play important roles in the occurrence of tumors as well as in the control of proliferation and differentiation of adult tissues, particularly in hematopoiesis. Numerous Hox genes are expressed in immature hematopoietic CD34+ cells whereas just some of them are expressed in more mature progenitors. Therefore, a major role of these genes in the commitment and differentiation of hematopoietic cells can be assumed. Other genes such as Pbx1, Meis1, Hox11, Pax5, Gbx2 or Lhx2 which encode non-HOX homeoproteins are also involved in hematopoiesis and/or leukemogenesis. The purpose of the present review is to summarize recent knowledges concerning specific roles of homeoproteins in the hematopoietic tissues and cells.