Sumoylation in axons triggers retrograde transport of the RNA-binding protein La

Authors:
van Niekerk EA, Willis DE, Chang JH, Reumann K, Heise T, Twiss JL
In:
Source: Proc Natl Acad Sci USA
Publication Date: (2007)
Issue: 104(31): 12913-8
Research Area:
Neurobiology
Cells used in publication:
PC-12
Species: rat
Tissue Origin: adrenal
Platform:
Nucleofectorâ„¢ I/II/2b
Abstract
A surprisingly large population of mRNAs has been shown to localize to sensory axons, but few RNA-binding proteins have been detected in these axons. These axonal mRNAs include several potential binding targets for the La RNA chaperone protein. La is transported into axonal processes in both culture and peripheral nerve. Interestingly, La is posttranslationally modified in sensory neurons by sumoylation. In axons, small ubiquitin-like modifying polypeptides (SUMO)-La interacts with dynein, whereas native La interacts with kinesin. Lysine 41 is required for sumoylation, and sumoylation-incompetent La(K41R) shows only anterograde transport, whereas WT La shows both anterograde and retrograde transport in axons. Thus, sumoylation of La determines the directionality of its transport within the axonal compartment, with SUMO-La likely recycling to the cell body.