Identification of novel functional regions important for the activity of HOXB7 in mammalian cells.
Members of the HOX family of homeobox transcription factors play a role in pattern formation in diverse developmental systems. The clearly documented role of HOX genes in the proliferation and differentiation of primary hematopoietic cells and cell lines provides a convenient system to pursue a biochemical analysis of HOX gene function in mammalian cells. To explore the role of HOXB7 in myeloid hematopoiesis, a number of mutations and deletions in the gene were constructed that targeted sequences with known functions or in regions that had not been examined previously. The wild-type and mutant B7 constructs were introduced into the murine myelomonocytic cell line, 32D, and assayed for their effects on G-CSF-induced myeloid differentiation. Wild-type HOXB7 inhibited the differentiation of 32D cells, whereas mutations in the Pbx-binding pentapeptide motif or the DNA-binding homeodomain, as well as internal deletions of the N-terminal unique region, blocked this effect. Interestingly, mutations eliminating two target sites for casein kinase II, the glutamate-rich C terminus, or the first 14 amino acids of HOXB7, led to enhanced 32D differentiation. A model proposing a role for these regions of HOXB7 is presented.
Yaron
Y
Y
Division of Hematology-Oncology, Department of Medicine, Jonsson Comprehensive Cancer Center, University of California School of Medicine, Los Angeles, CA 90095, USA.
McAdara
J K
JK
Lynch
M
M
Hughes
E
E
Gasson
J C
JC
D016475:3T3 Cells; D000818:Animals; D047390:Casein Kinase II; D002454:Cell Differentiation / Q000235:genetics; D002460:Cell Line; D002999:Clone Cells; D018076:DNA, Complementary / Q000235:genetics; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D006098:Granulocytes / Q000166:cytology / Q000201:enzymology; D006131:Growth Inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D020014:K562 Cells; D051379:Mice; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017384:Sequence Deletion; D014162:Transfection
D018076:DNA, Complementary; D006131:Growth Inhibitors; C490538:HOXB7 protein, human; D018398:Homeodomain Proteins; C093253:Hoxb7 protein, mouse; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D016179:Granulocyte Colony-Stimulating Factor; D005982:Glutathione Transferase; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases