Abstract
Subcellular localization of ribosomes defines the location and capacity for protein synthesis. Methods for in vivo visualizing ribosomes in multicellular organisms are desirable in mechanistic investigations of the cell biology of ribosome dynamics. Here, we developed an approach using split GFP for tissue-specific visualization of ribosomes in Caenorhabditis elegans. Labeled ribosomes are detected as fluorescent puncta in the axons and synaptic terminals of specific neuron types, correlating with ribosome distribution at the ultrastructural level. We found that axonal ribosomes change localization during neuronal development and after axonal injury. By examining mutants affecting axonal trafficking and performing a forward genetic screen, we showed that the microtubule cytoskeleton and the JIP3 protein UNC-16 exert distinct effects on localization of axonal and somatic ribosomes. Our data demonstrate the utility of tissue-specific visualization of ribosomes in vivo, and provide insight into the mechanisms of active regulation of ribosome localization in neurons.
Highlights
Localization of organelles defines the local environment and functionality of cells
Ribosome localization determines the local capacity for protein synthesis, which is important in polarized cells, such as neurons
Ca2+/calmodulin-dependent protein kinase II a(CaMKIIa) mRNA is localized to dendrites via a cis regulatory element in its 3’-UTR, and removal of this element impairs longterm potentiation (LTP) and spatial memory (Miller et al, 2002); b-actin mRNA is localized to the growing tip of an axon, the growth cone, where its polarized translation is important for growth cone turning towards an attractant (Leung et al, 2006; Yao et al, 2006)
Summary
Localization of organelles defines the local environment and functionality of cells. Ribosome localization determines the local capacity for protein synthesis, which is important in polarized cells, such as neurons. Ca2+/calmodulin-dependent protein kinase II a(CaMKIIa) mRNA is localized to dendrites via a cis regulatory element in its 3’-UTR, and removal of this element impairs longterm potentiation (LTP) and spatial memory (Miller et al, 2002); b-actin mRNA is localized to the growing tip of an axon, the growth cone, where its polarized translation is important for growth cone turning towards an attractant (Leung et al, 2006; Yao et al, 2006) Despite their potential impact on local translation, mechanisms underlying ribosome localization in vivo are largely unexplored, partly due to the limited tools to visualize ribosomes in live multicellular organisms. One striking example of ribosome localization is that dendritic ribosomes associated with the netrin receptor, Deleted in Colorectal Cancer (DCC), are stalled and inactive, and released upon netrin signaling (Tcherkezian et al, 2010)
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