An Unbiased cDNA Library Prepared from IsolatedAplysiaSensory Neuron Processes Is Enriched for Cytoskeletal and Translational mRNAs

Abstract

Local protein synthesis is required for long-lasting synapse-specific plasticity in cultured Aplysia sensorimotor synapses. To identify synaptically localized mRNAs, we prepared a cDNA library from isolated sensory neurites. By sequence analysis, we estimate that the library contains 263 distinct mRNAs, with 98 of these mRNAs constituting 70% of all clones. The localized transcripts are enriched for mRNAs encoding cytoskeletal elements and components of the translational machinery. In situ hybridization confirms that the mRNAs for at least eight of these transcripts are present in distal neurites. Immunocytochemistry reveals that serotonin regulates the translation of one of the localized mRNAs, that encoding alpha1-tubulin. Our identification of mRNAs encoding cytoskeletal elements suggests that local protein synthesis is required for the growth of new synaptic connections associated with persistent synaptic strengthening. Our finding of mRNAs encoding components of the translational machinery suggests that local protein synthesis serves to increase the translational capacity of synapses.

Regulation of global and specific mRNA translation by the mTOR signaling pathway

“…88,89 In fact, TOP mRNAs represent some of the most abundant transcripts localized within these structures. 90,91 While it seems unlikely that new ribosomes are assembled in this compartment, as this process is thought to strictly occur in the nucleolus, 92 the translation of TOP mRNAs may serve to selectively replace or replete translation factors and ribosomal proteins during times of increased demand in protein synthesis. 78 Another possibility is that certain elongation factors encoded by TOP mRNAs may be present in dendrites and axons in limiting amounts, such that increasing their expression by promoting TOP mRNA translation would significantly increase overall translation rates.…”

Identification of Process-Localized mRNAs from Cultured Rodent Hippocampal Neurons

“…Previous studies have described a role for local translation during axon guidance and learning-related synaptic plasticity (Martin, 2004). We and others (Miyashiro et al, 1994;Tian et al, 1999;Eberwine et al, 2001Eberwine et al, , 2002Moccia et al, 2003;Sung et al, 2004) have been interested in identifying the population of localized mRNAs, because these are likely to encode proteins that function to produce local changes in synaptic efficacy and structure.…”

Identification of a cis-acting element that localizes mRNA to synapses

“…In the brain, local protein synthesis is critical to the development and experience-driven refinement of neural circuits, playing roles in axon guidance, synaptogenesis, and synaptic plasticity (1,2). A large but select population of transcripts localizes to axons and dendrites (3)(4)(5)(6)(7)(8), indicating that local translation subserves diverse cell biological functions. Where studied, the localization of mRNAs to axons or dendrites has been shown to depend on cisacting localization elements (LEs) usually found in the 3′ UTR, although occasionally present in the coding sequence or 5′ UTR (1,2,9).…”