Studying the Role of Cyclin Dependent Kinase 5 (Cdk5) in Maintaining Healthy Neuronal Functions in Class I Dendritic Aborization Neurons of Drosophila
Open Access
- Author:
- Rudisill, Katelyn
- Area of Honors:
- Biochemistry and Molecular Biology
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Melissa Rolls, Thesis Supervisor
Song Tan, Thesis Honors Advisor - Keywords:
- Drosophila
Microtubules
Biochemistry
Molecular Biology
Neurons - Abstract:
- Proteins constituting the Wnt signaling pathway—γ-tubulin, Axin, Dsh, and Fz—regulate microtubule polarity in the dendrites of class I dendritic arborization (DA) neurons in Drosophila. Due to the distinct polarity of microtubules, microtubule motor proteins—dynein (minus end directed) and kinesin (plus end directed)—can ensure correct transport of cellular cargo within the cell. Within the dendrites, microtubule are oriented plus ends towards the cell body and minus ends directed away from the cell body. Previous studies indicate the Wnt proteins organize microtubule organization centers (MTOCs) to dendritic branch points in class I DA Drosophila neurons—this results in nucleation and maintenance of microtubules in the cell. Additionally, Cyclin Dependent Kinase 5 (Cdk5) exhibits important regulatory roles in neuronal cells. Given this, we aimed to study the role Cdk5 plays in regulating microtubule polarity in class I DA Drosophila neurons. We developed two alternate hypotheses to address our overarching question: H1) Cdk5 acts on proteins upstream of Axin within the Wnt signaling pathway or H2) Cdk5 acts directly on Axin through a parallel pathway outside of the Wnt pathway (Figure 4). Our experimental evidence showed depletion of Cdk5 in the cell resulted in decreased localization of γ-tubulin to dendritic branch points, and mixed microtubule polarity in the cell. Exploration of the localization patterns of various proteins involved in localizing γ-tubulin to dendritic branch points in class I DA Drosophila neurons—Axin, Dsh, APC2, and Fz—following knockdown of Cdk5 in the cells supports hypothesis 1: Cdk5 appears to act on proteins upstream of Axin within the Wnt signaling pathway. Furthermore, fluorescence microscopy experiments revealed Cdk5 localizing to the cell body of class I DA Drosophila neurons, which indicates Cdk5 could have other cellular functions, in addition to regulating microtubule dynamics.