Use of optical tweezers to probe epithelial mechanosensation

Andrew Resnick

Cellular mechanosensation mechanisms have been implicated in a variety of diseasestates. Specifically in renal tubules, the primary cilium and associated mechanosensitive ion channels are hypothesized to play a role in water and salt homeostasis, with relevant disease states including polycystic kidney disease and hypertension. Previous experiments investigating ciliary-mediated cellular mechanosensation have used either fluid flow chambers or micropipetting to elicit a biological response. The interpretation of these experiments in terms of the “ciliary hypothesis” has been difficult due the spatiallydistributed nature of the mechanical disturbance—several competing hypotheses regarding possible roles of primary cilium, glycocalyx, microvilli, cell junctions, and actincytoskeleton exist. I report initial data using optical tweezers to manipulate individual primary cilia in an attempt to elicit a mechanotransduction response—specifically, the release of intracellular calcium. The advantage of using laser tweezers over previous work is that the applied disturbance is highly localized. I find that stimulation of a primary cilium elicits a response, while stimulation of the apical surface membrane does not. These results lend support to the hypothesis that the primary cilium mediates transduction of mechanical strain into a biochemical response in renal epithelia.

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