Article Abstract:
Functional antagonism related to direct interaction of hematopoietic transcription factors GATA-1 and PU.1 exists in erythroid cells. Malignant transformation usually inhibits terminal cell differentiation but the mechanisms are not clear. PU.1 is a hematopoietic-specific Ets family transcription factor required for development of some lymphoid and myeloid lineages. It can act as an oncoprotein. Activation of expression in erythroid precursors by transgenesis or proviral insertion brings on erythroleukemias in mice. Stoichiometry of directly interacting, opposing transcription factors may be crucial as a determinant for governing processes of malignant transformation and normal differentiation. Ectopic expression of PU-1 in Xenopus embryos will block erythropoiesis in normal development.
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Article Abstract:
A GATA-2/estrogen receptor chimera which acts as a ligand-dependent negative self-renewal regulator is discussed. Estrogen and tamoxifen-inducible forms of GATA-2 were used to change levels of GATA-2 in the IL-3-dependent multipotential hematopoietic progenitor cell model FDCP mix and results suggest threshold GATA-2 functions in hematopoietic progenitor cells are critical in determining whether self-renewal or differentiation will occur.
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Article Abstract:
A cytoplasmic role for hnRNP D, a heterogeneous nuclear ribonucleoprotein able to go back and forth between cytoplasm and the nucleus, in mRNA destabilization in vivo directed by the AU-rich element is discussed. Studies to identify potential trans-acting factors for AU-rich RNA-destabilizing elements (ARE)-directed mRNA decay and to learn about cellular mechanisms have been carried out.
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