27 Influence of Polyadenylation-induced Translation on Metazoan Development and Neuronal Synaptic Function

Abstract

The oocytes of probably all metazoans contain a large store of dormant mRNAs that are destined for translation at subsequent stages of development. A substantial number of these molecules, generally referred to as masked or maternal mRNA, have relatively short poly(A) tails. When these tails lengthen in response to exogenous cues, translation ensues. Conversely, some translating mRNAs lose their poly(A) tails and, as a consequence, become translationally dormant. These dynamic changes in translation that are controlled by poly(A) addition and removal regulate early development. Although cytoplasmic polyadenylation has been known to be a hallmark of early animal development for some time, the extent to which it was used to modulate gene expression in late development or in adult tissues was unknown. It now appears that this regulatory process also takes place in the mammalian brain and may have important implications for synaptic function.

In this chapter, I focus on the molecular biology of cytoplasmic polyadenylation-induced translation. Studies that were published prior to 1996 will be discussed when necessary, but a general review of this topic prior to that date may be found in the first edition of this volume (Richter 1996; Wickens et al. 1996).

ESSENTIAL FEATURES OF A XENOPUS OOCYTE SIGNALING PATHWAY
Because much of the molecular biology of cytoplasmic polyadenylation is derived from work using Xenopus oocytes, it is important to outline some of the key features of the developmental process that makes these cells so useful for studying RNA processing and translational control. During the 3–6...