Regulation of mRNA Translation during cellular division.

Protein synthesis is a multistep, multifactorial process of mRNA translation, on which cells expend more energy than on any other activity. Cellular division into two daughter cells involves temporary inhibition of protein synthesis. In line with many translational control paradigms, global translation during mitosis is inhibited at the level of 5'cap-dependent initiation. The down regulation of global translation is accompanied by 5'cap-independent translational activation of specific mRNAs whose protein products have a role in the progression of cellular division. Recently, the elongation step was highlighted as a major target of translational control during mitosis, in addition to the initiation step. Stalling of translating ribosomes not only protects mRNAs during mitosis but also allows rapid resumption of active translation immediately upon entry into the G(1) phase of the cell cycle, an added dimension of energy saving. This review focuses on recent information related to translational regulation during cellular division and raises a new challenge regarding mechanism(s) employed by mRNAs whose translation is not sensitive to the elongation block.