COP9 limits dendritic branching via Cullin3-dependent degradation of the actin-crosslinking BTB-domain protein Kelch.
Components of the COP9 signalosome (CSN), a key member of the conserved 26S proteasome degradation pathway, have been detected to be altered in patients of several debilitating syndromes. These findings suggest that CSN acts in neural circuits, but the exact function of CSN in brain remains unidentified. Previously, using Drosophila peripheral nervous system (PNS) as a model system, we determined that CSN is a critical regulator of dendritic morphogenesis. We found that defects in CSN led to the strikingly contrast phenotype of either reducing or stimulating dendritic branching. In particular, we have reported that CSN stimulates dendritic branching via Cullin1-mediated proteolysis. Here we describe that CSN inhibits dendritic arborization in PNS neurons acting via control of Cullin3 function: loss of Cullin3 causes excessive dendritic branching. We also identified a downstream target for Cullin3-dependent degradation in neurons--the actin-crosslinking BTB-domain protein Kelch. Inappropriate accumulation of Kelch, either due to the impaired Cullin3-dependent turnover, or ectopic expression of Kelch, leads to uncontrolled dendritic branching. These findings indicate that the CSN pathway modulates neuronal network in a multilayer manner, providing the foundation for new insight into the CSN role in human mental retardation disorders and neurodegenerative disease.
Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America.
Inna
I
Djagaeva
Sergey
S
Doronkin
D000199:Actins / Q000737:chemistry*; D000818:Animals; D000075686:COP9 Signalosome Complex; D003433:Crosses, Genetic; D044842:Cullin Proteins / Q000096:biosynthesis / Q000502:physiology*; D003712:Dendrites / Q000378:metabolism*; D029721:Drosophila Proteins / Q000096:biosynthesis / Q000502:physiology*; D004331:Drosophila melanogaster / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008840:Microfilament Proteins / Q000096:biosynthesis / Q000502:physiology*; D046912:Multiprotein Complexes / Q000502:physiology*; D009154:Mutation; D009420:Nervous System / Q000378:metabolism*; D019636:Neurodegenerative Diseases / Q000378:metabolism; D009474:Neurons; D010447:Peptide Hydrolases / Q000502:physiology*; D017434:Protein Structure, Tertiary
D000199:Actins; C503647:Cul3 protein, Drosophila; D044842:Cullin Proteins; D029721:Drosophila Proteins; D008840:Microfilament Proteins; D046912:Multiprotein Complexes; C080353:kel protein, Drosophila; D010447:Peptide Hydrolases; D000075686:COP9 Signalosome Complex