The EBAX-type Cullin-RING E3 Ligase and Hsp90 Guard the Protein Quality of the SAX-3/Robo Receptor in Developing Neurons

• Published in: Neuron (Cambridge, Mass.) Vol. 79; no. 5; pp. 903 - 916
• Main Authors: Wang, Zhiping, Hou, Yanli, Guo, Xing, van der Voet, Monique, Boxem, Mike, Dixon, Jack E., Chisholm, Andrew D., Jin, Yishi
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 04.09.2013; Elsevier Limited
• Subjects: Animals; Caenorhabditis elegans; Caenorhabditis elegans Proteins - physiology; Cell adhesion & migration; Cullin Proteins - physiology; Disease; Drosophila; Elongin; Guards; HSP90 Heat-Shock Proteins; Insects; Mice; Nerve Tissue Proteins - biosynthesis; Nerve Tissue Proteins - metabolism; Nervous System - embryology; Nervous System - metabolism; Neurogenesis; Neurons; Protein folding; Protein synthesis; Quality control; Receptors, Immunologic - biosynthesis; Receptors, Immunologic - metabolism; Roundabout Proteins; Ubiquitin-Protein Ligases - physiology
• ISSN: 0896-6273; 1097-4199
• DOI: 10.1016/j.neuron.2013.06.035

Although protein quality control (PQC) is generally perceived as important for the development of the nervous system, the specific mechanisms of neuronal PQC have remained poorly understood. Here, we report that C. elegans Elongin BC-binding axon regulator (EBAX-1), a conserved BC-box protein, regulates axon guidance through PQC of the SAX-3/Robo receptor. EBAX-1 buffers guidance errors against temperature variations. As a substrate-recognition subunit in the Elongin BC-containing Cullin-RING ubiquitin ligase (CRL), EBAX-1 also binds to DAF-21, a cytosolic Hsp90 chaperone. The EBAX-type CRL and DAF-21 collaboratively regulate SAX-3-mediated axon pathfinding. Biochemical and imaging assays indicate that EBAX-1 specifically recognizes misfolded SAX-3 and promotes its degradation in vitro and in vivo. Importantly, vertebrate EBAX also shows substrate preference toward aberrant Robo3 implicated in horizontal gaze palsy with progressive scoliosis (HGPPS). Together, our findings demonstrate a triage PQC mechanism mediated by the EBAX-type CRL and DAF-21/Hsp90 that maintains the accuracy of neuronal wiring. •The EBAX-type Cullin-RING ligase controls axon guidance accuracy•EBAX-1 and Hsp90 collaboratively regulate the protein quality of SAX-3/Robo•Vertebrate EBAX shows conserved substrate preference toward Robo mutants•EBAX-1 facilitates thermotolerance of axon guidance during development Protein quality control mechanisms are largely unclear in the developing nervous system. Wang et al. report that the conserved EBAX-type Cullin-RING ubiquitin ligase and Hsp90 collaboratively guard SAX-3/Robo protein quality and axon guidance accuracy against intrinsic and extrinsic perturbations.