Multiple inhibitory cytokines induce deregulated progenitor growth and apoptosis in hematopoietic cells from Fac-/- mice.
We used a murine model containing a disruption of the murine homologue (Fac) of Fanconi Anemia group C (FAC) to evaluate the role of Fac in the pathogenesis of bone marrow (BM) failure. Methylcellulose cultures of BM cells from Fac-/- and Fac+/+ mice were established to examine the growth of multipotent and lineage-restricted progenitors containing inhibitory cytokines, including interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), and macrophage inflammatory protein-1alpha (MIP-1alpha). Clonogenic growth of Fac-/- progenitors was reduced by 50% at 50- to 100-fold lower concentrations of all inhibitory cytokines evaluated. We hypothesized that the aberrant responsiveness to inhibitory cytokines in clonogenic cells may be a result of deregulated apoptosis. To test this hypothesis, we performed the TUNEL assay on purified populations of primary BM cells enriched for hematopoietic progenitors or differentiated myeloid cells. After stimulation with TNF-alpha, accentuated apoptosis was observed in both populations of Fac-/- cells. In addition, deregulated apoptosis was also noted in the most immature phenotypic population of hematopoietic cells after stimulation with MIP-1alpha. Together these data suggest a role of Fac in affecting the signaling of multiple cytokine pathways and support cytokine-mediated apoptosis as a major mechanism responsible for BM failure observed in FA patients.
Haneline
L S
LS
Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Broxmeyer
H E
HE
Cooper
S
S
Hangoc
G
G
Carreau
M
M
Buchwald
M
M
Clapp
D W
DW
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D004268:DNA-Binding Proteins; D005199:Fanconi Anemia / Q000503:physiopathology; D052218:Fanconi Anemia Complementation Group C Protein; D051856:Fanconi Anemia Complementation Group Proteins; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D007371:Interferon-gamma / Q000378:metabolism; D019402:Macrophage Inflammatory Proteins / Q000378:metabolism; D008747:Methylcellulose / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D009687:Nuclear Proteins; D011506:Proteins / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D018797:Cell Cycle Proteins; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D004268:DNA-Binding Proteins; C497652:Fancc protein, mouse; D052218:Fanconi Anemia Complementation Group C Protein; D051856:Fanconi Anemia Complementation Group Proteins; D019402:Macrophage Inflammatory Proteins; D009687:Nuclear Proteins; D011506:Proteins; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D008747:Methylcellulose