Cell Biology, Neurobiology & Anatomy

Research Area: The role of intraflagellar transport (IFT) in the assembly and maintenance of the vertebrate photoreceptor sensory cilium

Research Area 1:  Live cell analysis of IFT in the zebrafish photoreceptor sensory cilium.

The outer segment (OS) of vertebrate photoreceptors is a sensory cilium which serves as a phototransduction organelle, and similar to other types of sensory cilia, proper assembly and maintenance of photoreceptor OSs depends on IFT. IFT is characterized by bi-directional motility of IFT particles along a microtubule backbone known as the axoneme. Like all microtubule based processes, IFT particle motility is driven by microtubule-based motor proteins, specifically, kinesin 2 family members (anterograde) and cytoplasmic dynein 2 (retrograde). Several studies utilizing genetic and biochemical approaches support a role for microtubule-based motor proteins in OS formation, however, direct visualization of this process has remained elusive. Through the use of fluorescently tagged motor proteins or IFT particles, real time imaging will be utilized to visualize IFT in zebrafish photoreceptor OSs, which should provide critical insight into the kinetics of this dynamic process.

Research Area 2:  Identification of KIF17 specific cargo required for photoreceptor OS formation.

KIF17, a kinesin 2 family member, has recently been identified as a novel component of photoreceptor IFT and knockdown of KIF17 results in severe disruption of OS formation (Insinna et al., 2008). In addition, recent findings have demonstrated that KIF17’s role in OS formation is regulated by a c-terminal specific CamKII phosphorylation event at a conserved serine residue (unpublished data). Because the c-terminus of KIF17 functions to link the motor to cargo we predict that this phosphorylation event functions to regulate the motor-cargo interaction. This project is designed to identify KIF17 specific cargo and investigate the role of phosphorylation in IFT. By utilizing dephosphorylation and phosphomimetic mutants, biochemical and proteomic techniques will be employed to identify KIF17 specific cargo. The identification of KIF17 specific cargo will provide a better understanding of what molecules are delivered by IFT and how this process is regulated. 

Education and Training:

2004-2010 PhD., University of Notre Dame, Notre Dame, IN (Supervised by Dr. Kevin Vaughan)

2002-2004 Research Technician, Indiana University, Bloomington, IN (Supervised by Dr. William Saxton and Dr. Susan Strome)

1998-2002 B.S., Indiana University, Bloomington, IN 

Publications:

Spike, CA., J. Bader, V. Reinke, S. Strome. (2008). “DEPS-1 promotes P-granule assembly and RNA interference in C. elegans germ cells. Development. 135: 983-93.

Hornick, J., J. R. Bader, K. Trimble, E. Tribble, J. S. Breunig, E. Halpin, K. T. Vaughan, and E. H. Hinchcliffe. (2008). “Live-cell analysis of mitotic spindle formation in taxol-treated cells”. Cell Motility and Cytoskeleton. 65: 595-613.

Whyte, J.*, J. R. Bader*, S. Tauhata, J. Hornick, K. Pfister, W. Lane, G. Chan, E. H. Hinchcliffe, P. S. Vaughan, and K. T. Vaughan. (2008). “Phosphorylation regulates targeting of cytoplasmic dynein to kinetochores during mitosis”. Journal of Cell Biology. 183: 819-34. (* Co-first authors)

Bader, J. R. and K.T. Vaughan. (2010). “Dynein at the kinetochore: Timing, Interactions, and Functions”. Seminars in Cell & Developmental Biology. 3: 269-75.