BioE Seminar: Active Fluctuations in Primary Cilia

Abstract: Primary cilia of kidney epithelial cells are believed to act as mechanosensors for kidney-duct fluid flow. Genetic defects localizing to the primary cilia are connected to polycystic kidney disease (PKD), a fatal monogenic disorder. Mechanical parameters such as flexural rigidity must modulate ciliary mechanosensation. It has been shown that there is a basal rotation component to ciliary deflection, which has the potential to affect aspects of mechanosensation. To investigate ciliary mechanical response, we have deflected primary cilia of Madin-Darby canine kidney (MDCK-II) cells with an optical trap and recorded their relaxation dynamics with video microscopy, and we have observed cilia fluctuations. We discovered that fluctuations are actively driven, although these primary cilia do not possess dynein motors that could deflect them. I will introduce a method to detect and quantitate thermodynamic non-equilibrium in the dynamics of primary cilia of kidney epithelial cells using the principle of detailed balance.