Directional Exosome Proteomes Reflect Polarity-Specific Functions in Retinal Pigmented Epithelium Monolayers.


The retinal pigmented epithelium (RPE) forms the outer blood-retinal barrier in the eye and its polarity is responsible for directional secretion and uptake of proteins, lipoprotein particles and extracellular vesicles (EVs). Such a secretional division dictates directed interactions between the systemic circulation (basolateral) and the retina (apical). Our goal is to define the polarized proteomes and physical characteristics of EVs released from the RPE. Primary cultures of porcine RPE cells were differentiated into polarized RPE monolayers on permeable supports. EVs were isolated from media bathing either apical or basolateral RPE surfaces, and two subpopulations of small EVs including exosomes, and dense EVs, were purified and processed for proteomic profiling. In parallel, EV size distribution and concentration were determined. Using protein correlation profiling mass spectrometry, a total of 631 proteins were identified in exosome preparations, 299 of which were uniquely released apically, and 94 uniquely released basolaterally. Selected proteins were validated by Western blot. The proteomes of these exosome and dense EVs preparations suggest that epithelial polarity impacts directional release. These data serve as a foundation for comparative studies aimed at elucidating the role of exosomes in the molecular pathophysiology of retinal diseases and help identify potential therapeutic targets and biomarkers.






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Publication Info

Klingeborn, Mikael, W Michael Dismuke, Nikolai P Skiba, Una Kelly, W Daniel Stamer and Catherine Bowes Rickman (2017). Directional Exosome Proteomes Reflect Polarity-Specific Functions in Retinal Pigmented Epithelium Monolayers. Scientific reports, 7(1). p. 4901. 10.1038/s41598-017-05102-9 Retrieved from

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Nikolai Petrovich Skiba

Associate Professor of Ophthalmology

My research focuses on applying mass spectrometry based proteomics to study proteins in eye tissues, cells and sub-cellular compartments to understand mechanisms of vision. An important aspect of my research is to identify proteins in different compartments of retinal photoreceptor cells, their amount and modification status at different cell states defined by the light conditions, genotype, disease etc. This information can be valuable in understanding molecular mechanisms of vision and biology of the photoreceptor cell. Another important aspect of my research is to assist basic scientist and clinicians in our department in their proteomic needs which include identification of proteins and other biomolecules in a given biological sample, detection of protein post-translational modifications and sequence variations, elucidation of protein-protein interactions and also characterization of changes in the protein concentration and composition in a biological sample at different conditions.


W Daniel Stamer

Joseph A.C. Wadsworth Distinguished Professor of Ophthalmology

My laboratory studies the disease of glaucoma, the second leading cause of blindness in the United States, affecting nearly 3 million people (70 million Worldwide). The primary risk factor for developing glaucoma is ocular hypertension (high intraocular pressure, IOP). IOP is a function of the regulated movement of aqueous humor into and out of the eye.  Elevated IOP in glaucoma is a result of disease in the primary efflux route, the conventional outflow pathway, affecting proper homeostatic control of aqueous humor drainage.

Lowering IOP in glaucoma patients, whether or not they have ocular hypertension, is important because large clinical trials involving tens of thousands of patients repeatedly demonstrate that significant, sustained IOP reduction slows or halts vision loss. Unfortunately, current first-line medical treatments do not target the diseased conventional pathway and do not lower IOP sufficiently in most people with glaucoma. Therefore, finding new, more effective ways to medically control IOP by targeting the conventional pathway is a central goal the Stamer Laboratory.

Using molecular, cellular, organ and mouse model systems, my laboratory seeks to identify and validate novel drug targets in the human conventional outflow pathway to facilitate the development of the next generation of treatments for ocular hypertension and glaucoma.

Bowes Rickman

Catherine Bowes Rickman

George and Geneva Boguslavsky Distinguished Professor of Eye Research

Dr. Bowes Rickman is a highly accomplished translational scientist whose research efforts over two decades have been focused on the molecular/cell biology and pathobiology of age-related macular degeneration (AMD). In an effort to better understand the pathophysiology of AMD, she has created a number of murine models that recapitulate many aspects of human AMD and point the way toward eventual treatments for AMD. Among many cited seminal contributions is her discovery of a connection between complement and lipoprotein metabolism and AMD and the development of a murine model that closely mirrors findings in humans. Using these models, Dr. Bowes Rickman has dissected disease mechanisms that contribute to AMD risk, and tested multiple novel therapeutic targets for its treatment.

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