Inhibition of mitochondrial dynamics in Dictyostelium discoideum through the overexpression of FszA and FszB proteins.

Mitochondria play a central role in cells through energy production, calcium regulation, and cell death regulation. Dysfunction of mitochondria can impair energy production causing cellular damage which could be detrimental to an organism. Mitochondrial dynamics such as fission, fusion, and motility determine the organelle's structure and can indicate the overall health of the cell. Dictyostelium discoideum, a well-established model for mitochondrial dynamics, contains two GTPase proteins that are predicted to mediate mitochondrial dynamics, FszA and FszB. In this study, we overexpressed GFP tagged FszA and FszB proteins to gain insight into their role in the mitochondrial dynamics of D. discoideum. Through live imaging, we quantified mitochondrial fission and fusion events, localization of the proteins with respect to fission and fusion events, and mitochondrial velocity. Results show that the overexpression of FszA-GFP, FszB-GFP, and GFP-FszB significantly decreased mitochondrial fission and fusion, and overexpressed GFP-FszA significantly decreased mitochondrial fusion compared to the control AX4 strain. Images of GFP-FszA and FszA-GFP strains showed little co-localization with the mitochondria during fission and fusion events, but GFP-FszB and FszB-GFP were localized to the mitochondria during fission events. Overexpression of FszB-GFP and GFP-FszB also significantly decreased mitochondrial velocity. The results of this study give insight into the underlying mechanism behind mitochondrial dynamics and could advance future studies in D. discoideum neurodegeneration models.