Dynein-2 intermediate chains play crucial but distinct roles in primary cilia formation and function

Abstract

The dynein-2 microtubule motor is the retrograde motor for intraflagellar transport. Mutations in dynein-2 components cause skeletal ciliopathies, notably Jeune syndrome. Dynein-2 comprises a heterodimer of two non-identical intermediate chains, WDR34 and WDR60. Here, we use knockout cell lines to demonstrate that each intermediate chain has a distinct role in cilia function. Both proteins are required to maintain a functional transition zone and for efficient bidirectional intraflagellar transport, only WDR34 is essential for axoneme extension. In contrast, only WDR60 is essential for co-assembly of the other subunits. Furthermore, WDR60 cannot compensate for loss of WDR34 or vice versa. This work defines a functional asymmetry to match the subunit asymmetry within the dynein-2 motor. Analysis of causative point mutations in WDR34 and WDR60 can partially restore function to knockout cells. Our data show that Jeune syndrome is caused by defects in transition zone architecture as well as intraflagellar transport.\n\nSUMMARYHere, Vuolo and colleagues use engineered knockout human cell lines to define roles for dynein-2 intermediate chains. WDR34 is required for axoneme extension, while WDR60 is not. Both subunits are required for cilia transition zone organization and bidirectional intraflagellar transport.