Aidan Flynn

2019 REU Student | Haswell Lab

Aidan Flynn is a rising junior at Washington University in St. Louis, majoring in Biology.  Aidan is working in Dr. Liz Haswell’s lab, studying how mechanosensitive channels in animals and plants respond to forces, particularly MSL10 dynamics in roots after osmotic shock.

Research Abstract:

Responding to the movement of water into and out of the cell and the turgor changes that correspond with this movement is a vital function in plants. An increase in turgor may occur in response to various external and internal stimuli, with two of the most prominent forces being mechanical stressors and exposure to a hypoosmotic environment that thereby results in a movement of water into the organism. If turgor becomes too high, plants become vulnerable to damage such as cell wall harm and cell bursting. Hypoosmotic stresses are in part alleviated by multimeric MscS-Like (MSL) ion channels that are present throughout cell and compartment membranes. MSL channels couple internal stimuli like changes in membrane tension with ion flux to alleviate osmotic swelling. MSL10, one of the most studied MSL proteins, has been linked to a suite of functions, including functioning as an anion-preferring ion channel that opens in response to increased cellular membrane stress as well as induction of cell death when expressed transiently in tobacco that is separable from its ion channel activity. Although it has been implicated in the osmotic response pathway, its relationship to and dynamics during hypoosmotic shock are yet to be characterized. Here we show that levels of MSL10-GFP are decreased after introduction of a hypoosmotic shock to the cell. Via confocal microscopy imaging, we found that MSL10-GFP fluorescent signal decreases by about 50% in the hour following downshock. This property has been determined to be reliant on the launching of a downshock, as no change in MSL10-GFP signal was seen when an isosmotic shock was provided to the cell. Our results reveal an additional functional link between MSL10 and other members of the MSL family of proteins that have already been shown to act as an osmotic safety valve in the instance of a downshock. These findings also improve our understanding of the purpose of mechanosensitive ion channels and their conserved regions.