MPA treatment induces redistribution of B23 into the nucleoplasm and
inhibits pre-rRNA synthesis. A, MPA treatment induces
redistribution of B23 into the nucleoplasm. U2OS cells were treated with
methanol or 10 μmol/liter MPA for different time points (h). The cells were
immunostained with anti-B23 (green) and anti-NS (red) as
well as DAPI for DNA. B, MPA treatment inhibits pre-rRNA synthesis.
U2OS cells were treated with 10 μmol/liter MPA for different time points
(h). Total RNAs were prepared from cells and retrotranscribed. Real-time PCR
analysis was then conducted to determine the relative expression of the
pre-rRNA as normalized against GAPDH mRNA. Similar results are shown using two
pairs of primers amplifying a fragment between 5′-ETS and 18S rRNA
(a) and a fragment between 18S rRNA and ITS-1 (b),
respectively, as indicated in the diagram illustrating the pre-rRNA gene
structure in the top panel. C, effect of MPA treatment on
levels for 5S rRNA, tRNATyr, nucleolin, and ARPP P0 RNAs. U2OS
cells were treated with 10 μmol/liter MPA for 12 h, and total RNAs were
prepared from cells and retrotranscribed. Real-time PCR analysis was then
conducted to determine the relative expression of the RNAs as normalized
against GAPDH mRNA.