Arshavsky
Principal Investigator
Helena Rubinstein Foundation Distinguished Professor of Ophthalmology
Professor in Ophthalmology
Co Vice-Chair of Basic Science Research
Scientific Director, Ophthalmology
Professor of Cell Biology
Professor in Pharmacology & Cancer Biology
Faculty Network Member of the Duke Institute for Brain Sciences
Contact Information

Duke Eye Center, AERI, Rm 5012
2351 Erwin Road
Durham, NC 27710

Office: 919-668-5391
Fax: 919-684-3826
Email: vadim.arshavsky@duke.edu

Overview

The biology and pathophysiology of vertebrate photoreceptor cells

Rod and cone photoreceptors are sensory neurons responsible for the detection of light and transforming the information entering the eye in the form of photons into neuronal activity ultimately transmitted to our brain. Our laboratory is interested in elucidating the molecular mechanisms underlying signal transduction, subcellular compartmentalization and maintenance of the healthy state of these cells.

Support Inherited Retinal Disease Discovery

Lab image

Research Projects

Currently, we pursue three major experimental directions:

Photoreceptors are highly compartmentalized neurons, with all molecular events responsible for generating light-signals confined to the outer segment, a ciliary organelle containing a stack of flattened membranous “discs”. Building this organelle involves two interconnected processes – formation of its unique anatomical structure and populating it with a unique set of signaling and structural proteins. We study both of these processes in our laboratory.

Central to our interests is the complex process of photoreceptor disc morphogenesis, which continues throughout the entire lifetime of a photoreceptor. A new disc is added at the base of the outer segment every ~20 minutes, while old discs are shed from the outer segment tip by the retinal pigment epithelium. The formation of a new disc starts with evagination of the plasma membrane at the outer segment base, followed by lateral membrane outgrowth, flattening, and, in the cases of rods and mammalian cones, subsequent disc enclosure. Our laboratory investigates every step of this process. Several years ago, we made an important conceptual connection between the processes of photoreceptor disc morphogenesis and the formation of extracellular vesicles, ectosomes, ubiquitously produced by various primary cilia. We demonstrated that, like most other primary cilia, the photoreceptor outer segment has an innate ability to release ectosomes, but in normal photoreceptors this process is suppressed by the protein called peripherin-2 (akaPRPH2 or rds). Membranes retained at the outer segment through this mechanism are used to build photoreceptor discs through their elongation, flattening and enclosure.

Lab image 1
A hypothesis on the evolutionary origin of the outer segment. The outer segment evolved through introduction of the photoreceptor-specific protein, peripherin-2, which enabled prototypic photoreceptors to retain ectosomes at the cilium. Subsequent adaptations allowed flattening, elongation and enclosure of retained membrane material to form photoreceptor discs.

A critical role in disc morphogenesis is played by actin cytoskeleton whose expansion drives membrane evagination upon formation of new discs. We found that this process is dependent on the polymerization of branched actin in a mechanism resembling the formation of lamellipodia in migrating cells. This actin network expansion is initiated by the pentameric WAVE complex containing a unique subunit, WASF3. WAVE complexes are known to mediate between the upstream signaling pathways and downstream actin networks. Thus, our current efforts are directed to identifying such an upstream signaling pathway that is responsible for initiating the formation of each new disc with the striking frequency of approximately 80 times per day.

Lab image 2
On the left are electron micrographs of outer segments from normal rod photoreceptors with disc stacks inside. On the right is outer segment from a mutant rod unable to initiate actin network expansion. Instead of forming disc stacks, these outer segments produce disorganized membrane whorls.

 Our second major direction is to address the pathobiological mechanisms underlying degenerative diseases of the retina and develop practical approaches to ameliorate these debilitating conditions. Previously, we showed that a major stress factor leading to photoreceptor cell death in a broad spectrum of inherited retinal degenerations is “proteasomal overload,” i.e., insufficient capacity of the ubiquitin-proteasome system to degrade vast amounts of misfolded or mistargeted proteins produced as a result of the underlying mutations. We further demonstrated that genetic enhancement of proteasomal activity in mouse rods results in a striking delay in photoreceptor degeneration resulting from mutations in multiple proteins, including the relatively common P23H mutation of rhodopsin. Currently, we are focused on exploring translational implications of these studies by seeking practical approaches to enhance photoreceptor proteostasis using small molecules and gene therapy approaches.

Lab image 5
Subretinal delivery of AAV-based gene therapy into a mouse eye.

 In the course of our studies, we are exploring high-end applications of mass spectrometry-based proteomics. Our laboratory was the first to adopt several advanced proteomic approaches to our field. One of them is protein correlation profiling used for elucidation of multiple protein distributions among different compartments of the photoreceptor cells and for identification of unique protein components of various photoreceptor membranes. Using this approach, we demonstrated that a small protein PRCD (progressive rod and cone degeneration) is a unique component of photoreceptor discs and subsequently identified three novel unique components of the plasma membrane enclosing the rod outer segment. Most recently, we adopted a highly efficient and accurate methodology for simultaneous absolute quantification of many proteins in the same sample, termed “MS Western”. This method allowed us to determine the precise molar ratio amongst all major functional and structural proteins residing in the light-sensitive outer segments of photoreceptor cells.

Lab image 4
Cartoon illustrating the exact number of molecules for membrane proteins located within the space of one quarter of a photoreceptor disc and the corresponding segment of the plasma membrane.  Symbol sizes do not reflect the actual dimensions of the proteins; rather, less abundant proteins are shown as larger symbols for ease of visualization.

Lab Members

Associate Professor of Ophthalmology
Medical Instructor in the Department of Ophthalmology
Research Associate
Research Analyst
Research Analyst
Research Technician
Ophthalmology Resident
Undergraduate
Arshavsky lab team
Left to right, back row: Tylor Lewis, PhD, Penelope Ferry-Leeper, BS, GCTC, RAC, Oleg Alekseev, MD, PhD
Left to right front row: Natasha Klementeva, PhD, Lauren Cao, BS, Lin Yu, PhD, Stella Finkelstein, MS, Carson Castillo, MS, Margaux Kreitman, PhD, Vadim Arshavsky, PhD

 

Selected Publications

Skiba, N.P., Lewis. T.R., Spencer, W.J., Castillo, C.M., Shevchenko, A., Arshavsky, V.Y.  Absolute quantification of photoreceptor outer segment proteins. J. Proteome Res. (2023) 22, 2703-2713.

Lewis, T.R., Phan, S., Castillo, C.M., Kim, K.-Y., Coppenrath, K., Thomas, W., Hao, Y., Skiba, N.P., Horb, M.E., Ellisman, M.H., Arshavsky, V.Y.  Photoreceptor disc incisures form as an adaptive mechanism ensuring the completion of disc enclosure. eLife (2023) 12:e89160.

Spencer, W.J., Schneider, N.F., Lewis, T.R., Castillo, C.M., Skiba, N.P., Arshavsky, V.Y.  The WAVE complex drives the morphogenesis of the photoreceptor outer segment cilium. Proc. Natl. Acad. Sci. USA. (2023) 120:e2215011120.

Skiba, N.P., Cady, M.A., Molday, L., Han, J.Y.S., Lewis, T.R., Spencer, W.J., Thompson, W.J., Hiles, S., Philp, N.J., Molday, R.S., Arshavsky, V.Y.  TMEM67, TMEM237 and embigin in the complex with lactate transporter MCT1 are unique components of the photoreceptor outer segment plasma membrane. Mol. Cell. Proteomics (2021) 20:100088.

Spencer, W.J., Lewis, T.R., Pearring, J.N., Arshavsky, V.Y.  Photoreceptor discs: built like ectosomes. Trends Cell Biol. (2020) 30, 904-915.

Spencer, W.J., Lewis, T.R., Phan, S., Cady, M.A., Serebrovskaya, E.O., Schneider, N.F., Kim, K.-W., Cameron, L.A., Skiba, N.P., Ellisman, M.H., Arshavsky, V.Y.  Photoreceptor disc membranes are formed through an Arp2/3-dependent lamellipodium-like mechanism. Proc. Natl. Acad. Sci. USA. (2019) 116, 27043-27052.

Lobanova, E.S., Finkelstein, S., Li, J., Travis, A.M., Hao, Y., Klingeborn, M., Skiba, N.P., Deshaies, R.J., Arshavsky, V.Y.  Increased proteasomal activity supports photoreceptor survival in inherited retinal degeneration. Nat. Commun. (2018) 9:1738.

Salinas, R.Y., Pearring, J.N., Ding, J.D., Spencer, W.J., Hao, Y., Arshavsky, V.Y.  Photoreceptor discs form through peripherin-dependent suppression of ciliary ectosome release. J. Cell Biol. (2017) 216, 1489-1499.

View full list of publications

Positions Available

Our lab is currently looking to fill a postdoctoral position to study basic and translational photoreceptor biology.

Interested candidates, please send your CV via email to Vadim Arshavsky.