Primary cilia are cell surface-localized, microtubule-based organelles that are involved in various signal transduction pathways. The transition zone (TZ) of the primary cilia houses numerous proteins that are critical to proper ciliary function. When TZ proteins are mutated, they can cause large-scale ciliary dysfunction, and can lead to disorders known as ciliopathies in humans. One such ciliopathy is Nephronophthisis (NPHP), a cystic kidney disease that is associated with mutations found in the TZ protein NPHP4. Although it is known for its link to cystic kidney disease, NPH has additional variable phenotypes. We hypothesize that the variable phenotypes seen in ciliopathy patients are aggregate effects of several mutations. Due to the similarity in primary cilia form and function between humans and nematodes, we are using C. elegans as a model to explore
nphp-4 gene interactions. The objective of my project is to validate
cca-1 as a novel regulator of
nphp-4 for proper primary cilia function. Previously, our lab conducted an EMS mutagenesis screen in C. elegans to identify potential genes that may interact with
nphp-4. One such gene that was identified was
cca-1, which encodes a voltage-gated calcium channel subunit. We have confirmed the genetic interaction between
cca-1 and
nphp-4 through the use of the DiI dye-filling assay for ciliary integrity. Moving forward, we plan to investigate changes in ciliary structure and sensory behaviors in
cca-1,
nphp-4, and double mutants. We also plan to experiment with live imaging of calcium dynamics to determine whether
cca-1's known functions are related to its role in primary cilia. We hope that this work done in C. elegans demonstrates how the interaction of
cca-1 and
nphp-4 is critical for normal primary cilia function, ultimately illustrating how a
cca-1 mutation can be linked to NPH patients.