The Role of Severing Protein Kat60L1 in Neuronal Microtubule Maintenance

open_access
Open Access
Author:
Quinn, Thomas
Area of Honors:
Biochemistry and Molecular Biology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Melissa Rolls, Thesis Supervisor
Scott E. Lindner, Thesis Honors Advisor
Keywords:
Neurons
Neurodegenerative Disease
Microtubules
Neurology
Microscopy
Enzymes
Reverse Genetics
Abstract:
Neurons are the functional unit of the nervous system, a vast and far-spreading cellular system responsible for several aspects of survival, including both voluntary and involuntary sensory input, motor output, and higher order functions such as consciousness, memory, and emotion. Neuronal microtubules provide a highway network used by motor proteins to carry molecular components, such as neurotransmitters packaged in vesicles, from one part of the cell to another. Neurons are also dynamic cells that can adjust and respond to morphological changes such as growth, structural remodeling, or injury response. Thus, neurons employ microtubule-severing proteins: severases responsible for regulating the microtubules–or highway network–of the neuron. In Drosophila, four different severases (Spastin, Fidgetin, Katanin, and Kat60L1) have been identified, and three of these (Spastin, Fidgetin, and Katanin) have been further examined to find implications in neurodegenerative diseases such as Alzheimer’s Disease. Severase Kat60L1–the least-studied of these severases–is being examined using in vivo live imaging in a Drosophila system to investigate the specific functions of this poorly studied protein. Through imaging assays utilizing a confocal scanning laser microscope, the role of Kat60L1 in neuronal microtubule regulation was investigated. It was initially theorized that the severase mediated microtubule dynamics in a manner similar to Katanin, severing the stable domain of microtubules to create new plus and minus ends; however, the results of these assays indicate that Kat60L1 plays a novel role in minus-end microtubule growth and stability to modulate microtubule array and dynamics. Specifically, the results indicate that Kat60L1 may encourage minus end growth and stability through the introduction of nanodamage to the minus end, a mechanism previously observed in Katanin and Spastin at the plus ends.