ABSTRACT: We used Fancd2-/- mice to understand its mechanism of action. Transcriptome analysis of cKit+ Sca1+ Lin- (KSL) cells discovered that only four genes changed their expression levels significantly after chronic OXM administration in both Fancd2−/− and wild-type mice: mKi67 and Cenpf were up-regualted by 1.4 fold; Spp1 and Oasl2 were significantly down-regulated by 10.5 and 1.5 fold, respectively. Both mKi67 and Cenpf genes are cell cycle-regulated genes and proliferation markers. Their up-regulation was consistent with our observation in flow cytometry analysis that oxymetholone stimulated the proliferation of hematopoietic stem and progenitor cells. RNAseq analysis showed no effects on mTert mRNA expression with chronic androgen therapy, but instead suggested down-regulation of Spp1 and Oasl2 as an important mechanism for the drug’s action. Our RNAseq analysis also revealed that Fancd2−/− KSL cells showed clear changes in mRNA expression profiles compared to wild-type controls: 430 genes were down-regulated by more than 1.5 fold, whereas 159 genes were up-regulated. Gene ontology analysis revealed key pathways to be significantly altered in Fancd2−/− KSL cells. Besides the abnormal cell cycle status expected from our earlier flow cytometry analysis, surprisingly we noticed that a group of genes involved in immune responses and inflammation, comprising Cfp (Properdin), Socs2, Ccr1, Ccr2, Ccr5, Chga (Chromogranin A), Ifi30 (Interferon Gamma-Inducible Protein 30), Lgmn, Txn, and Sell (selectin L), were up-regulated in Fancd2−/− KSL cells. We therefore hypothesize that some genes up-regulated in FA HSPCs may be part of an innate immune response to DNA damage. In addition, whole bone marrow cells were also analyzed in parallel with KSL cells. As compared to whole bone marrow cells, the genes enriched in KSL cells in wild-type mice were listed in details in the corresponding publication. This information can be a good resource for the future gene expression analysis of HSPCs. Finally, we compared the gene expression profiles of early progenitors between OXM-treated and placebo-treated mice. There were no significant differences at all in gene expression between OXM-treated wild-type erythroid progenitors and their placebo-treated wild-type counterparts, with no genes displaying an expression change higher than 1.2 fold. Importantly, no up-regulation of EPO-inducible genes such as Socs1, Socs2, Socs3, and Cish was seen in wild-type mice treated with OXM. Furthermore, there was no differential expression of the well-known EPO target transferrin receptor or any other major players of the Epo-R signaling network such as Bcl2l1, Cdc25a, Btg3, Ccnd2, Lyl1, Pim3, and Tnfrsf13c. These results indicate that EPO might not play a role in the action of OXM in the erythroid lineage.
