Investigating the potential interaction of RBM4 withTranslational machinery in C2C12 cells undergoingmyogenic differentiation

RBM4 has already been shown to be involved in myogenic differentiation and it has also been shown to interact with eIF4G and eIF4A in HeLa cells while under arsenite stress, what has not been investigated is whether RBM4 interacts with eIF4G or eIF4A or other parts of the translational machinery during myogenic differentiation. This work is divided into 3 parts that each focus on RBM4 during myogenic differentiation. In the first section, I present data that looks at RBM4 expression levels total and both its isoforms RBM4a and RBM4b. Both total rbm4 and RBM4b increase in expression whereas RBM4a decrease as differentiation progresses. I also present data investigating potential regulation of RBM4 with data showing RBM4a mRNA expression decrease while RBM4b mRNA expression increases. The second section focus on the potential role of p38MAPK kinase phosphorylation of serine 309 on RBM4 as a regulator of localisation of RBM4 and of RBM4 on general protein translation and its incorporating into the eIF4F complex and the data presented shows that RBM4 appears to not respond to p38 MAPK activity as observed in hela cells and that RBM4 is incorporated into eIF4F complex and that when overexpressed has a negative effect on RBM4 especially when it can not be phosphorylated on serine 309. The final section focuses on RBM4 interaction with eIF4G and eIF4A both of which it binds during myogenic differentiation, but does not appear to bind eIf4G in vitro directly