Erythroid differentiation in vitro is blocked by cyclopamine, an inhibitor of hedgehog signaling.
Adult hematopoietic differentiation is a developmental process that employs many of the same molecular mechanisms as embryogenesis. To explore the possibility that hedgehog signaling is involved in the control of hematopoietic differentiation, we screened a panel of human leukemia cell lines for the expression of Patched1 and Smoothened, the receptor and coreceptor for hedgehog ligands. Expression was found in multiple cell lines, and Patched1 expression was detected in normal marrow. Induction of myeloid differentiation in cell lines downregulated expression of both genes. When normal marrow mononuclear cells were grown in semisolid medium in the presence of 10 microM cyclopamine, development of colonies of granulocytic/monocytic lineage was unaffected in terms of both number and morphology. The number of erythroid colonies, however, was significantly reduced (P < 0.01). Furthermore, hemoglobinization was substantially delayed relative to controls in those erythroid colonies that did form. Incubation of hematopoietic progenitors with Shh-N and GM-CSF resulted in increased granulocyte/monocyte colonies (P < 0.01); the increase was blocked by cyclopamine. Incubation of hematopoietic progenitors with Shh-N and stem cell factor resulted in larger erythroid colonies. These results suggest that elements of the hedgehog signaling pathway are involved in the control of hematopoietic differentiation.
Detmer
K
K
Division of Basic Medical Sciences, Mercer University School of Medicine, Macon, Georgia 31207, USA. detmer.k@gain.mercer.edu
Walker
A N
AN
Jenkins
T M
TM
Steele
T A
TA
Dannawi
H
H
D002454:Cell Differentiation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D018922:HL-60 Cells; D053823:Hedgehog Proteins; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D020014:K562 Cells; D008565:Membrane Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D011506:Proteins / Q000494:pharmacology / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000235:genetics; D043562:Receptors, G-Protein-Coupled; D015398:Signal Transduction / Q000187:drug effects*; D000072086:Smoothened Receptor; D015534:Trans-Activators; D014407:Tumor Cells, Cultured; D020298:U937 Cells; D014704:Veratrum Alkaloids / Q000494:pharmacology*
D053823:Hedgehog Proteins; D008565:Membrane Proteins; C000606236:PTCH1 protein, human; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D011506:Proteins; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; C509239:SHH protein, human; C491023:SMO protein, human; D000072086:Smoothened Receptor; D015534:Trans-Activators; D014704:Veratrum Alkaloids; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; C000541:cyclopamine