David B. Doroquez, Ph.D.

Postdoctoral Fellow

Ph.D., Biology, Massachusetts Institute of Technology, 2007

B.S., Biology, Santa Clara University, 1999

doroquez [at] brandeis.edu

The role of intracellular trafficking in modulating ciliary structural morphology in C. elegans

Primary cilia are organelles that serve as environmental sensors, and are present on nearly all cell types in vertebrates. Each cilium consists of a central microtubular axoneme surrounded by a membrane. The structure and biogenesis of these organelles are highly conserved from the green alga Chlamydomonas to human, which allows for parallel studies of cilia in a variety of model animal systems. Defects in cilia biology have now been implicated in multiple diseases, including polycystic kidney disease, Bardet-Biedl syndrome, sensory pathologies, and retinopathies.

Intracellular trafficking of a transmembrane receptor from the ER to the cilum.

The soil nematode Caenorhbaditis elegans is an ideal system to study cilia biology with its experimental tractability and the ability to nalyze each of its 60 ciliated sensory neurons. These cilia are essential for multiple sensory functions including chemosensation. Individual olfactory neurons exhibit highly specialized cilia structures that are essential for their unique sensory functions. Cell-specific mechanisms of intraflagellar transport (IFT) and sensory signaling contribute to ciliary structural and morphological diversity. In particular, sensory signaling is required to modulate the specialized architecture of the AWB olfactory neuron cilia and this modulation is dependent on vesicular trafficking. Little is known about the regulation of vesicular trafficking in cilia formation and maintenance. Defects in trafficking mechanisms are likely to affect cilia structure and function due to altered transport and localization of ciliary signaling molecules resulting in defective cellular homeostasis.

The overall goal of this investigation is to study the role of intracellular trafficking in the generation and maintenance of cilia morphology in C. elegans. In order to identify components involved in C. elegans cilia biology, we have taken a proteomics-based approach. We have identified proteins associated with different IFT complex proteins and motors via mass spectrometry. Many predicted IFT-associated components were identified in this analysis, suggesting that this approach may allow us to identify new cilia-related components. Interestingly, we have identified vesicular trafficking proteins associated with IFT complex proteins. In current work, we are characterizing the roles of identified vesicular trafficking proteins in the regulation of cell-specific cilia biogenesis and the maintenance of sensory signaling. These experiments will serve to elucidate the role of vesicular transport in the regulation of cilia structure, and provide new information about how these sensory organelles are built and maintained. These studies may provide insights into the basic biology underlying ciliopathies.