The myeloid zinc finger gene-1 (MZF-1) encodes a putative transcription factor whose expression has been implicated in myeloid differentiation. To study the role of the nMZF-1 in myploid differentiation,we characteriz...The myeloid zinc finger gene-1 (MZF-1) encodes a putative transcription factor whose expression has been implicated in myeloid differentiation. To study the role of the nMZF-1 in myploid differentiation,we characterized MZF-1 protein expr.ession,cellular localization,and phosphorylation in leukemia cell lines and leukemia cells.MZF1 protein expression was found only in myeloid cells. In proliferating HL-60 cells,MZF-1 was localized to the nucleus with some cytoplasmic distribution; however,upon retinoic acid (RA)induced granulocytic differentiation, MZF-1 became restricted to the nucleus.In32 PO4-la labelled HL-60 cell, MZF-1 was immunoprecipitated as a phosphoprotein doublet of 53￣54kDa. MZF-1 phosphorylation increased after acute stimulation of HL-60 with granulocytemacrophage colony stimulating factor (GM-CSF), interleukin-3(IL-3),phorbol ester,and serum.Chronic GM-CSf treatment of HL-60 cells potentiating granulocytic differentiation sustained the hyperphosphorylated state of MZF-1,whereas chronic treatment with TPA leading to monocytic-macrophage differentiation was accompanied by the disappearance of the 53 kDa MZF-1 phosphoprotein and the appearance of cross-reactive 69 and 105kDa phosphoprotein species. K562 human myeloblastic cells which are resistant to granulocytic differentiation express both the 53 kDa MZF-1 protein and the cross reactive 69 and 105 kDa proteins,but the 53 kDa MZF-1 protein is not detectable phosphorylated under any experimental conditions. Acute promyelocytic leukemic cells exhibited the 53kDa phosphoprotein,whereas monocytic leukemia cells expressed only the 69 and 105 kDa MZF-1 related phosphoproteins. The studies demonstrate that MZF-1 is a nuclear protein whose phosphorylation is associated with the granulocytic commitment of myeloid cells.展开更多
文摘The myeloid zinc finger gene-1 (MZF-1) encodes a putative transcription factor whose expression has been implicated in myeloid differentiation. To study the role of the nMZF-1 in myploid differentiation,we characterized MZF-1 protein expr.ession,cellular localization,and phosphorylation in leukemia cell lines and leukemia cells.MZF1 protein expression was found only in myeloid cells. In proliferating HL-60 cells,MZF-1 was localized to the nucleus with some cytoplasmic distribution; however,upon retinoic acid (RA)induced granulocytic differentiation, MZF-1 became restricted to the nucleus.In32 PO4-la labelled HL-60 cell, MZF-1 was immunoprecipitated as a phosphoprotein doublet of 53￣54kDa. MZF-1 phosphorylation increased after acute stimulation of HL-60 with granulocytemacrophage colony stimulating factor (GM-CSF), interleukin-3(IL-3),phorbol ester,and serum.Chronic GM-CSf treatment of HL-60 cells potentiating granulocytic differentiation sustained the hyperphosphorylated state of MZF-1,whereas chronic treatment with TPA leading to monocytic-macrophage differentiation was accompanied by the disappearance of the 53 kDa MZF-1 phosphoprotein and the appearance of cross-reactive 69 and 105kDa phosphoprotein species. K562 human myeloblastic cells which are resistant to granulocytic differentiation express both the 53 kDa MZF-1 protein and the cross reactive 69 and 105 kDa proteins,but the 53 kDa MZF-1 protein is not detectable phosphorylated under any experimental conditions. Acute promyelocytic leukemic cells exhibited the 53kDa phosphoprotein,whereas monocytic leukemia cells expressed only the 69 and 105 kDa MZF-1 related phosphoproteins. The studies demonstrate that MZF-1 is a nuclear protein whose phosphorylation is associated with the granulocytic commitment of myeloid cells.
