FIG. 8.

Differentiation-dependent regulation of the stability of the target RNA containing 3′-100/50 by growth factors via NPM in vitro. LS and US cells were stimulated with TGF-β (10 ng/ml), BMP 2 (200 ng/ml), PDGF (10 ng/ml), or CCN2 (30 ng/ml) for 24 h in the absence of FBS or left alone (−) as a negative control, and the cytoplasmic extract was obtained. Radiolabeled RNA (Luc-3′-100/50) was incubated with the cytoplasmic extracts (10 μg) in the absence (−) or presence of recombinant chicken NPM (0.1 μg). After timed intervals, the RNA was purified and subjected to urea-denaturing 6% PAGE. In the graphs at the bottom of the panel, the relative remaining amounts and fitted degradation curves of RNA standardized against each RNA at time zero (negative control [closed ovals and solid line] and NPM [closed rectangles and dotted line]) are shown on semilogarithmic graphs (value at time zero = 100). Note the opposite effects of growth factors on the reporter RNA stability between the two, both of which were abolished when excess NPM was added. Statistically significant differences in the absence of NPM between the values of growth factor-treated groups and the control group are indicated by asterisks as follows: *, P < 0.05.