Neurodegenerative Mutation in Cytoplasmic Dynein Alters Its Organization and Dynein-Dynactin and Dynein-Kinesin Interactions

Gareth Banks,Elizabeth M.C. Fisher,Majid Hafezparast,Wenhan Deng,Violetta Soura,Benjamin Dombert,Caroline Garrett,Marcel P. van der Brug

doi:10.1074/jbc.m110.178087

Gareth Banks, Elizabeth M.C. Fisher + Show 6 more

Open Access

https://doi.org/10.1074/jbc.m110.178087

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Abstract

A single amino acid change, F580Y (Legs at odd angles (Loa), Dync1h1Loa), in the highly conserved and overlapping homodimerization, intermediate chain, and light intermediate chain binding domain of the cytoplasmic dynein heavy chain can cause severe motor and sensory neuron loss in mice. The mechanism by which the Loa mutation impairs the neuron-specific functions of dynein is not understood. To elucidate the underlying molecular mechanisms of neurodegeneration arising from this mutation, we applied a cohort of biochemical methods combined with in vivo assays to systemically study the effects of the mutation on the assembly of dynein and its interaction with dynactin. We found that the Loa mutation in the heavy chain leads to increased affinity of this subunit of cytoplasmic dynein to light intermediate and a population of intermediate chains and a suppressed association of dynactin to dynein. These data suggest that the Loa mutation drives the assembly of cytoplasmic dynein toward a complex with lower affinity to dynactin and thus impairing transport of cargos that tether to the complex via dynactin. In addition, we detected up-regulation of kinesin light chain 1 (KLC1) and its increased association with dynein but reduced microtubule-associated KLC1 in the Loa samples. We provide a model describing how up-regulation of KLC1 and its interaction with cytoplasmic dynein in Loa could play a regulatory role in restoring the retrograde and anterograde transport in the Loa neurons.

Highlights

Cytoplasmic motor dynein is a multisubunit motor protein involved in the retrograde transport of membranous organelles, signaling endosomes, kinetochores, and other cargos along microtubules (MTs)2 (1, 2)
Legs at odd angles (Loa) Mutation Alters the Composition of Cytoplasmic Dynein Complex—In our Western blot analysis of the brain homogenates for the levels of DHC, DIC, and DLIC, we did not find any difference in protein levels between the wild type and Loa
We asked whether the Loa mutation affects the organization of dynein and the integrity of the dynein-dynactin complex

Summary

Introduction

Cytoplasmic motor dynein is a multisubunit motor protein involved in the retrograde (minus end) transport of membranous organelles, signaling endosomes, kinetochores, and other cargos along microtubules (MTs)2 (1, 2).

Results

Conclusion