Figure 2. Culture in the presence of RA increases Sox10, but EDN3 suppresses this effect.
p75NTR+ cells were grown for 72 hours in the presence of RA, EDN3, RA with EDN3, or neither compound. When EDN3 was absent, the EDN signaling inhibitor BQ-788 was added to inhibit endogenous EDNRB signaling. Relative Sox10 (A–B) and Ret (C–D) mRNA levels were measured by quantitative RT-PCR after 3 (A, C) and 14 (B, D) days. Expression is normalized to β-actin and the -RA/-EDN3 condition was standardized to a value of 1. Solid lines denote a statistically significant difference (p<0.05) between “No RA” and “RA”, and broken lines indicate a p value >0.05. Asterisk denotes a statistically significant difference (p<0.05) between “No EDN3” and “EDN3”. (A) In the absence of EDN3, RA increased Sox10 levels; however, the concurrent addition of EDN3 abolished this phenomenon. There was a statistically significant interaction (ⓧ; p=0.019) between EDN3 and RA in their effect on Sox10 levels at 3 days. This interaction is specific to Sox10 expression and was not observed with Ret. (B) RA treatment was associated with increased Sox10 levels but EDN3 had no effect at 14 days. (C) RA decreased Ret levels at 3 days regardless of whether EDN3 was present, but EDN3 did not affect Ret gene expression. (D) Decreased Ret levels in response to RA persisted at 14 days, but only in the presence of EDN3