Axonemal dyneins and force generation by neurons in Drosophila melanogaster ear

Analogous to vertebrate hair cells, the mechanosensory cilia of Drosophila auditory neurons are motile and serve dual, transducing and actuating roles. Structurally, the latter cilia resemble non-motile primary cilia, raising the question of how they generate motility. Two axonemal dynein motors are described in this thesis that are expressed in the fly’s auditory neurons and differently contribute to cilium motility: Whereas one dynein is required to generate motility, the other dynein regulates this motility by interacting with transient receptor potential ion channels of the vanilloid subfamily. Motility generation is shown to involve interactions between dyneins and yet another TRP channel, which together with dyneins seems to promote motility. This links auditory cilium motility to molecular motors and shows that this motility involves multiple interactions between the TRP channels and motor proteins

Forkhead Transcription Factor Fd3F Cooperates with Rfx to Regulate a Gene Expression Program for Mechanosensory Cilia Specialization

Cilia have evolved hugely diverse structures and functions to participate in a wide variety of developmental and physiological processes. Ciliary specialization requires differences in gene expression, but few transcription factors are known to regulate this, and their molecular function is unclear. Here, we show that the Drosophila Forkhead box (Fox) gene, fd3F, is required for specialization of the mechanosensory cilium of chordotonal (Ch) neurons. fd3F regulates genes for Ch-specific axonemal dyneins and TRPV ion channels, which are required for sensory transduction, and retrograde transport genes, which are required to differentiate their distinct motile and sensory ciliary zones. fd3F is reminiscent of vertebrate Foxj1, a motile cilia regulator, but fd3F regulates motility genes as part of a broader sensory regulation program. Fd3F cooperates with the pan-ciliary transcription factor, Rfx, to regulate its targets directly. This illuminates pathways involved in ciliary specialization and the molecular mechanism of transcription factors that regulate them