Translational repression by SESA is growth medium dependent

Abstract

The correct separation of chromosomes during mitosis is necessary to prevent genetic instability and aneuploidy which causes cancer, and other diseases. The main criteria for this is the correct duplication of the centrosome. Recently, we reported that Smy2 can suppress the essential role of MPS2 in the insertion of yeast centrosome into the nuclear membrane and co-operates with Eap1, Scp160, Asc1 for this task. We gave the name SESA (Smy2, Eap1, Scp160, Asc1) network to the system consisting of these four proteins. Detailed analysis showed that the SESA system is part of a mechanism which regulates translation of POM34 mRNA. Thus, SESA, is a system which suppresses spindle pole body (SPB) duplication defects by inhibiting the translation of POM34 mRNA (Sezen, 2009). Although many important points regarding SESA network have been discovered, many others remain obscure. How SESA system is activated, what is the trigger factor for Pom34 down regulation remains to be solved. In an attempt to uncover this, we came up with a surprising finding that translational repression of Pom34 by the SESA network is dependent on the growth medium. SESA is active when cells are grown in YPDA, but inactive in SC-Leu medium.