Probing Cell Signaling Networks in Microfluidic Devices

Abstract

Detection of signals is critical for the function of eukaryotic cells. D. discoideum cells are particularly adept at responding chemical gradients, sensing single percent concentration changes across their body. We measure the ability of the cells to sense gradients through this developmental transition as they change their internal machinery. Additionally, we impair the ability of the cells to modulate the speed of the receptors and measure the effect of a single receptor state on gradient sensing over development. We find a novel link between mechanotransduction and autophagy through the actin-rich microvillar protrusions lining the gut. These protrusions on the apical cell surface share structural similarities to the mechanosensitive stereocilia in the inner hair cells of the ear. Intestinal epithelial monolayers with microvilli, when exposed to persistent fluid shear stress, developed large vacuoles lined with autophagy associated proteins LC3 and LAMP1. The size and number of vacuoles were suppressed by perturbations to the autophagy pathway, including small molecule inhibitors and LC3 knockdown as well as through perturbations to the microvilli. Our results establish a link between apical shear and autophagic trafficking in intestinal epithelial monolayers.