Transition of mitochondrial fission through optogenetically engineered calcium oscillations

Abstract

Mitochondrial dynamics consists of fusion and fission states which regulate the quality and morphology of mitochondria in addition to determining the cellular events such as apoptosis and the cell cycle Therefore we focused on investigating mitochondrial dynamics in this study We applied an optogenetic method to trigger mitochondrial dynamics and transfected the photo-inducible protein channel calcium translocating channelrhodopsin (CatCh) onto the cell membrane to mimic cytosolic calcium oscillation by 470-nm blue light illumination The illumination could be precisely controlled by modifying various parameters such as power density frequency and duty cycle; more specifically customized illumination conditions could trigger unique calcium oscillation waves to trigger specific signal pathways In this study the mitochondria were illuminated under optimal intervals of illumination parameters to observe optogenetic-induced mitochondrial dynamics The results showed that application of illumination to cells expressing CatCh changed the mitochondrial dynamics from the fusion state to the fission state Moreover the illumination triggered phosphorylation at the Ser616 site of the mitochondrial fission protein Drp1 but did not phosphorylate the anti-mitochondrial fission protein Drp1-S637 and had no effects on the mitochondrial fusion proteins mitofusin-1 (Mfn1) and Mfn2 The results also allowed us to identify the candidate upstream signal pathways that cause optogenetics-induced mitochondrial fission Thus this study provides an effective and innovative method to control mitochondrial dynamics with a more precise resolution in both temporal and spatial dimensions

Date of Award	2021
Original language	English
Supervisor	Wen-Tai Chiu (Supervisor)