Autophagy and Mechanotransduction in the Trabecular Meshwork

ABSTRACT The trabecular meshwork (TM) is a pressure sensitive tissue located in the anterior segment of the eye, key regulator of intraocular pressure. Malfunction of this tissue results in improper drainage of aqueous humor (AH) outflow, leading to ocular hypertension, the major risk factor for developing glaucoma. The TM consists of an irregular lattice of collagen beams lined by TM endothelial-like cells, followed a zone of loose connective tissue- containing TM cells, through which AH must pass before leaving the eye. Changes in pressure gradients and fluid flow associated with eye movement, circadian rhythm or the ocular pulse cause small and high variations in intraocular pressure (IOP), which are translated in continuous cycles of tissue deformation and relaxation. Cells in the TM are known to be able of sensing these deformations as mechanical forces and respond to them by eliciting a variety of different responses. Our laboratory has identified activation of autophagy and the nuclear translocation of the autophagy marker LC3, in TM cells following application of mechanical stretch. Activation of autophagy was also observed in TM cells quickly after pressure elevation in porcine perfused eyes and in ocular hypertensive mouse models. This prompted us to propose autophagy as a crucial physiological response triggered in TM cells in response to strain to adapt to mechanical forces and maintain cellular homeostasis, which exerts a dual role in repair and mechanotransduction. The nature of the mechanosensor, mechanosignaling, and exact roles of autophagy in TM cell and tissue function are still not characterized. The goal of this application is to investigate an interplay between autophagy, primary cilium and mechanotransduction in TM cells and to determine the role of such interplay in outflow pathway physiology and pathophysiology. More in particular, we will test the hypothesis that autophagy plays a critical role in TM mechanotransduction by maintaining primary cilia prevalence and length, and that dysregulation of autophagy with aging and in the glaucomatous outflow pathway compromises primary cilia-dependent IOP homeostatic response. We anticipate that completion of this project will contribute to a further understanding of the role of autophagy in outflow pathway tissue physiology and pathophysiology. Most relevant, our studies have the potential of identifying a novel therapeutic target for the treatment of ocular hypertension and glaucoma.