Hot-wiring dynein-2 establishes roles for IFT-A in retrograde train assembly and motility

Intraflagellar transport (IFT) trains, built around IFT-A and IFT-B complexes, are carried by opposing motors to import and export ciliary cargo. While transported by kinesin-2 on anterograde IFT trains, the dynein-2 mo-tor adopts an autoinhibitory conformation until it needs to be activated at the ciliary tip to power retrograde IFT. Growing evidence has linked the IFT-A complex to retrograde IFT; however, its roles in this process remain unknown. Here, we use CRISPR-Cas9-mediated genome editing to disable the dynein-2 autoinhibi-tion mechanism in Caenorhabditis elegans and assess its impact on IFT with high-resolution live imaging and photobleaching analyses. Remarkably, this dynein-2 hot-wiringapproach reignites retrograde motility in-side IFT-A-deficient cilia without triggering tug-of-war events. In addition to providing functional evidence that multiple mechanisms maintain dynein-2 inhibited during anterograde IFT, our data establish key roles for IFT-A in mediating motor-train coupling during IFT turnaround, promoting retrograde IFT initiation, and modulating dynein-2 retrograde motility.

Automated summary

This study investigates the impact of disabling the autoinhibition mechanism of dynein-2 on intraflagellar transport (IFT) using genome editing techniques in Caenorhabditis elegans. The results show that retrograde transport can be reactivated in IFT-A-deficient cilia by activating dynein-2 using a "hot-wiring" approach, providing functional evidence for dynein-2 autoinhibition during anterograde IFT and establishing key roles for IFT-A in regulating retrograde transport.