Elucidation of the Molecular Mechanisms Driving Genetically-Induced High Myopia

ABSTRACT The goal of this K08 Mentored Clinical Scientist Research Career Development Award application is to provide the candidate with advanced skills needed to establish an independent research program investigating the pathogenesis and therapeutics of monogenic high myopia (HM) and inherited retinal dystrophies (IRDs). Our overall hypothesis is that increased TGFβ signaling drives HM progression and structural changes in the posterior segment indicative of pathological myopia (PM) in Marfan syndrome (MFS) and Rbp3-mediated retinitis pigmentosa (RP). To test this hypothesis, the specific aims are to: 1) Determine the extent that Smad2/3 activation contributes to myopia progression, PM changes and retinal degeneration in MFS and Rbp3-/- mice; 2) Define a role for TGFβ-dependent MAPK activation in myopia progression, PM changes and retinal degeneration in MFS and Rbp3-/- mice. This is based on an extensive review of the literature and our high-quality preliminary data demonstrating that: 1) MFS mice have significantly greater axial length (AL) and -9D myopic shift compared to WT littermates; 2) MFS mouse eyes show increased Smad2/3 and MAPK (Erk1/2, Jnk1/2, p38) activation in the ciliary body and retina; 3) AL and myopic shift are reduced in MFS mice after Erk inhibition; 4) Smad3-/- mice display shorter AL and a prominent hyperopic shift compared to WT littermates. These data indicate that TGFβ downstream pathways represent novel therapeutic targets for myopia and/or PM in MFS. Prior studies illustrated that loss-of-function mutations in RBP3 cause autosomal recessive RP with HM (-12 to -17D) in humans, while Rbp3-/- mice show markedly increased AL and myopic shift, as well as in-vivo and ex-vivo evidence of progressive retinal degeneration. This offers an opportunity to evaluate a role for TGFβ signaling in this etiologically-distinct form of monogenic myopia, with the goal of identifying and targeting common drivers of disease progression. The candidate is proposing a comprehensive training plan, combining formal coursework, meetings, seminars and workshops overseen by his diverse, experienced mentorship team. His specific training goals include to: 1) Refine his knowledge of in-vivo phenotyping of myopia and PM in mice, encompassing mouse eye biometry, autorefraction, fundus photography and optical coherence tomography (OCT); 2) Develop skills in in- vivo phenotyping of IRDs and their complications in mice, including ERG, OCT, and optomotor response (OMR); 3) Enhance his skills in ex-vivo histopathological and biochemical analysis of mouse myopia and IRD models, including PM changes (e.g. retinal detachment, retinoschisis, posterior staphyloma) and retinal degeneration (e.g. retinal thinning, photoreceptor loss); 4) Acquire management skills to build a successful independent laboratory; 5) Develop leadership skills in collaborative research; 6) Refine his communication and writing skills to successfully apply for R01 funding; 7) Continue training in responsible conduct of research. His training plan will be executed in coordination with the research activities described above. Results from this proposal will be used to develop a future R01 research plan that will facilitate the candidate’s transition to independent research.