Tet2-deficient HSC do not show increased contribution to hematopoiesis. (A) Pdzk1ip1-CreER R26^Tom/Tom mice were crossed with the Cre-inducible null Tet2 (Tet2^fl/fl) allele. Tet2^fl/fl or WT reporter mice were induced with tamoxifen (0.5 mg), and Tom expression in the PB was analyzed monthly. Shown are the fractions of Tom⁺ cells in the indicated cell types. Symbols represent the mean ± SD of Tet2^fl/fl (n = 2) or WT (n = 2) reporter animals. (B)Tet2^fl/fl or WT reporter animals were aged for 18 mo and treated with tamoxifen (1 mg), and the accrual of labeled Tom⁺ cells was examined monthly (arrowheads) in PB. After 6 mo, Tet2^fl/fl or WT mice were sacrificed for the endpoint analysis. (C) Cell labeling in the PB. Shown are fractions of Tom⁺ cells in the indicated blood cell types in old Tet2^fl/fl or WT mice at the indicated time points after tamoxifen treatment. Symbols represent the mean ± SD of Tet2^fl/fl (n = 6) or WT (n = 4) reporter animals. (D–F) Accrual of Tom⁺ cells at the endpoint. Shown are fractions of Tom⁺ cells in the mature cell types in the spleen (D) and BM (E), and in stem/progenitor cell populations (F). Symbols represent individual mice; bars represent the mean ± SD; data are from a single experiment. No statistically significant differences were observed. (G) Cre-induced Tet2^fl recombination in Tom⁺ or Tom⁻ total BM cells 6 mo after tamoxifen treatment. Genomic PCR was performed on DNA extracted from Tom⁺ or Tom⁻ cells sorted from WT, Tet2^fl/fl, or Tet2^fl/wt reporter mice; each lane represents an individual mouse. PCR products corresponding to the WT (250-bp), unrecombined Tet2^fl (flox, 430-bp), and Cre-recombined Tet2^fl (null, 550-bp) alleles are indicated. (H) Densitometric ratios of the recombined (null)-to-unrecombined (flox) amplicons for the genotyping data in panel G. Symbols represent individual mice; bars represent the mean ± range. Source data are available for this figure: SourceData FS2.