Transcription factors are present in fetal calf serum

Purpose. Successful cell cultures, particularly trabecular meshwork (TM) explants and TM cell cultures, frequently require the presence of fetal calf serum (FCS). Several commercially available FCS preparations were analyzed by hyaluronic acid (HA) affinity columns and Western blots to explore the possibility that transcription factors (TFs) are present in FCS. Methods. We selected a panel of commercially available antibodies - some directed against TFs and others against nuclear proteins - containing a consensus HA-binding motif of [R,H,K]-X(7)-[R,H,K] where X was any amino acid except D/E. FCS was applied to EAH-Sepharose-HA-affinity columns to obtain an enriched HA-binding protein fraction. The HA-bound proteins were eluted, fractionated by SDS polyacrylamide gel electrophoresis, transferred to Immobilon P, immunoblotted with antibodies and detected by enhanced chemiluminescence. Results. A partial list of immunopositive TFs includes E2F-1, ets-1/-2, GATA-2, TFIID, SRE/ZBP, as well as p53, Rb, and WT. Conclusions. The results indicate that FCS contains TFs. Notably, there are differences in the type and the amount of TFs from the different commercially available sources of FCS. Consequently, the source and the lot number of FCS may represent factors in successful cell culture. Secondly, HA may serve a role as a carrier of TFs to influence cell activity.