Stromal cell CD9 regulates differentiation of hematopoietic stem/progenitor cells.
CD9 belongs to the transmembrane 4 superfamily, and has been shown to influence cell proliferation, motility, and adhesion. We show here that ligation of CD9 modifies proliferation and/or differentiation of hematopoietic stem/progenitors. Pluripotent EML-C1 hematopoietic cells were cocultured with MS-5 stromal cells in the presence of KMC8.8, an anti-CD9 antibody. Numbers of recovered EML-C1 cells were slightly reduced and the antibody caused the hematopoietic cells to migrate beneath the adherent stromal cell layer. Of particular interest, EML-C1 cells recovered from CD9-ligated cultures had undifferentiated properties. Separate pretreatment of the two cell types with antibody showed that stromal-cell CD9 mediated these responses. Spontaneous expression of erythroid marker was completely blocked and there was a shift towards undifferentiated clonogenic progenitors. Immunoprecipitation studies showed that stromal-cell CD9 associates with the beta1 subunit of integrin, as well as a novel 100 kD protein. Antibody cross-linking of cell surface CD9 increased the amount of 100 kD protein that was subsequently coprecipitated with CD9. These observations show that stromal-cell CD9 influences physical interactions with hematopoietic cells and may be one factor that determines the degree of stem cell differentiation.
Aoyama
K
K
Second Department of Internal Medicine, Osaka University Medical School, Osaka, Japan.
Oritani
K
K
Yokota
T
T
Ishikawa
J
J
Nishiura
T
T
Miyake
K
K
Kanakura
Y
Y
Tomiyama
Y
Y
Kincade
P W
PW
Matsuzawa
Y
Y
D000818:Animals; D015703:Antigens, CD / Q000502:physiology*; D002448:Cell Adhesion; D002454:Cell Differentiation; D002633:Chemotaxis; D018920:Coculture Techniques; D004921:Erythropoietin / Q000494:pharmacology; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D019012:Integrin beta1 / Q000502:physiology; D007377:Interleukin-3 / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000502:physiology; D051379:Mice; D011994:Recombinant Proteins / Q000494:pharmacology; D019089:Stem Cell Factor / Q000494:pharmacology; D017154:Stromal Cells / Q000166:cytology / Q000502:physiology*; D060245:Tetraspanin 29
D015703:Antigens, CD; C554869:CD9 protein, human; C554870:Cd9 protein, mouse; D019012:Integrin beta1; D007377:Interleukin-3; D008562:Membrane Glycoproteins; D011994:Recombinant Proteins; D019089:Stem Cell Factor; D060245:Tetraspanin 29; D004921:Erythropoietin