Figure 5

The effects of a potassium channel blocker and ionophore on cell cycle, proliferation and endogenous gene expression in HDFs used for cell reprogramming. (A) Cell cycle analysis indicated that tetraethylammonium (TEA) moderately prolonged the G1 phase in a dose-dependent manner. In contrast, salinomycin (SAL) appeared to facilitate G1 phase progression. (B) Histograms representing cellular DNA content revealed that the 72-hr treatment of 10 mM TEA increased the number of cells in the G1 phase (G1 cells), while the 72-hr treatment of 25 nM SAL decreased the number of G1 cells. Neither TEA nor SAL caused noticeable cell death, supported by the absence of an increase in sub-G1 cells. (C) The number of HDFs (1 × 10⁵) after the indicated 96-hr treatment was determined by cell counting (*P < 0.05, t-test). (D) The expression of the endogenous POU5F1, SOX2, KLF4 and MYC genes in HDFs that underwent reprogramming with TEA and SAL was measured by qRT-PCR. Early in reprogramming, the induction of endogenous POU5F1 and SOX2 gene expression with and without VPA was suppressed by TEA (upper panel), but increased by SAL without VPA (lower panel). The induction of both genes was relatively unchanged by SAL in reprogramming with VPA (*P < 0.05, t-test, fold change ≥2). D9: cell samples collected at 9 days after the initial transduction (5 days after treatments began). All data are presented as mean ± standard deviation (n = 3) in each bar graph.