The central dogma of molecular biology states that when genes are turned on, DNA makes RNA that makes proteins. The current understanding of how genes are turned on and off centers on the first of these steps: changing the amount of RNA produced from various regions of DNA genome (transcriptional control). The role of translational control through changing the amount of proteins made on RNA is less understood. This project will investigate the cell machinery that controls the first steps of protein synthesis on RNA. The researchers will investigate how mutations in some parts of this translation initiation machinery impair growth of neural cells and cause early death in animals, in particular insects.
One of the Eukarya-specific translation factor complex is the multi-initiation factor complex (MFC) made of four eukaryotic initiation factors, eIF1, eIF2, eIF3, eIF5 and Met-tRNAiMet. It plays essential roles in stringent translation initiation at AUG codon. Human eIF5-mimic protein 1 (5MP1) binds eIF2 and eIF3 through eIF5-mimic C-terminal domain and inhibits translation. Thus, this is the first protein that was identified as the potential regulator of the MFC function. An important consequence of MFC regulation (eIF2 inhibition) is to up-regulate the translation of ATF4, the transcription factor governing amino acid synthesis and stress resistance. In this project, cultured insect cell lines, including neuronal cell lines, will be used to study 5MP interactions with translational machineries and 5MP regulation of ATF4 translation. In the fruit fly, genetic evidence suggests that 5MP is involved in axon guidance. Using the second insect model organism Tribolium castaneum (red flour beetle), it is aimed at examining whether 5MP or ATF4 knockdown causes defects in axon guidance and determining which protein partner of 5MP can regulate this biological process and whether this is done through ATF4.
