Phototransduction in the photoreceptor outer segment (OS), a sensory cilium, is among the best- understood neural signaling systems, but the molecular details and regulation of assembly of the OS remain unclear. During the past grant period we focused on intraflagellar transport (IFT), a conserved pathway mediated by two kinesin 2 family motors, kinesin II and KIF17. Photoreceptors coordinate renewal and turnover of photosensitive discs according to light-dark cycles, and diurnal changes in intracellular calcium regulate the activity of kinases like CaMKII. This proposal is based on our recent finding that that phosphorylation of KIF17 at a conserved serine in its tail domain facilitates its association with IFT machinery. Furthermore, mutation of this serine in the zebrafish sequence to an aspartate results in entry into the OS and increased OS turnover through disc shedding, and KIF17 abundance and phosphorylation state are regulated in a diurnal pattern. These findings lead to the hypothesis that KIF17 mediated IFT is regulated in relationship to OS turnover and influences turnover through regulation of the dynamics of the distal ciliary axoneme at the OS tip.
Aim 1 will analyze the KIF17 loss of function mutations in both zebrafish and mice to assess the overall importance of this motor in photoreceptors compared to other cilium types.
Aim 2 will use coordinated analysis of OS turnover, axoneme organization and KIF17 dynamics in zebrafish using transgenic models to test the hypothesis a KIF17 regulates the distal axoneme dynamics, which in turn is coupled to OS turnover.
Aim 3 will utilize real time imaging in isolated zebrafish photoreceptors to study KIF17 movement in the distal OS segment and its relationship to IFT motility. Completion of these aims will provide insight into fundamental regulatory functions of OS segment assembly that are directly relevant photoreceptor diseases.

Public Health Relevance

Maintenance of the light detection system in photoreceptors depends on turnover of its macromolecules at a high rate throughout life. Disruption of this turnover system leads to degeneration and blindness. Turnover requires molecular motors that move on microtubule tracks. This proposal identifies and analyzes a new molecular motor and addresses its function in photoreceptors and its role in regulating turnover of the light detection system.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-BDPE-N (09))
Program Officer
Neuhold, Lisa
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Medical College of Wisconsin
Anatomy/Cell Biology
Schools of Medicine
United States
Zip Code
Fogerty, Joseph; Besharse, Joseph C (2014) Subretinal infiltration of monocyte derived cells and complement misregulation in mice with AMD-like pathology. Adv Exp Med Biol 801:355-63
Fogerty, Joseph; Besharse, Joseph C (2011) 174delG mutation in mouse MFRP causes photoreceptor degeneration and RPE atrophy. Invest Ophthalmol Vis Sci 52:7256-66
Scoma, Heather Dehlin; Humby, Monica; Yadav, Geetha et al. (2011) The de-ubiquitinylating enzyme, USP2, is associated with the circadian clockwork and regulates its sensitivity to light. PLoS One 6:e25382
Insinna, Christine; Baye, Lisa M; Amsterdam, Adam et al. (2010) Analysis of a zebrafish dync1h1 mutant reveals multiple functions for cytoplasmic dynein 1 during retinal photoreceptor development. Neural Dev 5:12
Insinna, Christine; Luby-Phelps, Katherine; Link, Brian A et al. (2009) Analysis of IFT kinesins in developing zebrafish cone photoreceptor sensory cilia. Methods Cell Biol 93:219-34
Bhowmick, Reshma; Li, Mei; Sun, Jun et al. (2009) Photoreceptor IFT complexes containing chaperones, guanylyl cyclase 1 and rhodopsin. Traffic 10:648-63
Insinna, Christine; Humby, Monica; Sedmak, Tina et al. (2009) Different roles for KIF17 and kinesin II in photoreceptor development and maintenance. Dev Dyn :
Insinna, Christine; Besharse, Joseph C (2008) Intraflagellar transport and the sensory outer segment of vertebrate photoreceptors. Dev Dyn 237:1982-92
Insinna, Christine; Pathak, Narendra; Perkins, Brian et al. (2008) The homodimeric kinesin, Kif17, is essential for vertebrate photoreceptor sensory outer segment development. Dev Biol 316:160-70
Luby-Phelps, Katherine; Fogerty, Joseph; Baker, Sheila A et al. (2008) Spatial distribution of intraflagellar transport proteins in vertebrate photoreceptors. Vision Res 48:413-23

Showing the most recent 10 out of 32 publications