Transforming growth factor-beta1 transcriptionally activates CD34 and prevents induced differentiation of TF-1 cells in the absence of any cell-cycle effects.
A number of cytokines modulate self-renewal and differentiation of hematopoietic elements. Among these is transforming growth factor beta1 (TGF-beta1), which regulates cell cycle and differentiation of hematopoietic cells, but has pleiotropic activities depending on the state of responsiveness of the target cells. It has been previously shown by us and other authors that TGF-beta1 maintains human CD34(+) hematopoietic progenitors in an undifferentiated state, independently of any cell cycle effects, and that depletion of TGF-beta1 triggers differentiation accompanied by a decrease in CD34 antigen expression. In the present work, we show that exogenous TGF-beta1 upregulates the human CD34 antigen in the CD34(+) cell lines TF-1 and KG-1a, but not in the more differentiated CD34(-) cell lines HL-60 and K-562. We further studied this effect in the pluripotent erythroleukemia cell line TF-1. Here, TGF-beta1 did not effect cell growth, but induced transcriptional activation of full-length CD34 and prevented differentiation induced by differentiating agents. This effect was associated with nuclear translocation of Smad-2, activation of TAK-1, and with a dramatic decrease in p38 phosphorylation. In other systems TGF-beta1 has been shown to activate a TGF-beta-activated kinase 1 (TAK1), which in turn, activates p38. The specific inhibitor of p38 phosphorylation, SB202190, also increased CD34 RNA expression, indicating the existence of a link between p-38 inhibition by TGF-beta1 and CD34 overexpression. Our data demonstrate that TGF-beta1 transcriptionally activates CD34 and prevents differentiation of TF-1 cells by acting independently through the Smad, TAK1 and p38 pathways, and thus provide important clues for the understanding of hematopoietic development and a potential tool to modify response of hematopoietic cells to mitogens or differentiating agents.
Marone
M
M
Dept of Gynecology, Catholic University, Rome Italy.
Scambia
G
G
Bonanno
G
G
Rutella
S
S
de Ritis
D
D
Guidi
F
F
Leone
G
G
Pierelli
L
L
D018952:Antigens, CD34 / Q000096:biosynthesis* / Q000235:genetics; D002453:Cell Cycle / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D016895:Culture Media, Serum-Free; D016207:Cytokines / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000502:physiology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects*; D019254:Genes, bcl-2; D018922:HL-60 Cells / Q000187:drug effects / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D020014:K562 Cells / Q000187:drug effects / Q000378:metabolism; D004915:Leukemia, Erythroblastic, Acute / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D020930:MAP Kinase Kinase Kinases / Q000502:physiology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D010766:Phosphorylation / Q000187:drug effects; D011494:Protein Kinases / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D012334:RNA, Neoplasm / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051899:Smad2 Protein; D015534:Trans-Activators / Q000502:physiology; D014158:Transcription, Genetic / Q000187:drug effects*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases; D000099151:MAP Kinase Kinase Kinase 7
D018952:Antigens, CD34; D016895:Culture Media, Serum-Free; D016207:Cytokines; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D007093:Imidazoles; D020930:MAP Kinase Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D009363:Neoplasm Proteins; D011494:Protein Kinases; D019253:Proto-Oncogene Proteins c-bcl-2; D011725:Pyridines; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D051899:Smad2 Protein; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D048051:p38 Mitogen-Activated Protein Kinases; D000099151:MAP Kinase Kinase Kinase 7; C497782:SMAD2 protein, human; C508960:TGFB1 protein, human; C090942:4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)imidazole