This research proposal aims to elucidate the mechanisms for how gap junctions and cytoskeletal components coordinately regulate fiber cell assembly and cell surface interlocking structures to achieve fundamental optical and biomechanical properties of the lens. Lens fiber cell interlocking structures provided by membrane/cytoskeletal structures are essential for lens hemostasis, elasticity and transparency. Gap junctions in lens fiber cells predominantly consist of Cx46 (Gja3) and Cx50 (Gja8) connexins in human and mouse lenses. Gja3 and Gaj8 mutations cause various types of cataracts in humans and mice. Cataractogenesis caused by these connexin mutations is associated with dysfunctional gap junction channels, impaired lens homeostasis and degradation of crystallin proteins. However, the molecular and cellular mechanisms underlying the sequential steps of these pathological events are not well understood. It is unknown how connexin gene mutations lead to various types of cataracts, especially when an identical gene mutation leads to different types of cataracts in human individuals and in different mouse strain backgrounds. Our recent results show that surface tongue-and-groove structures are eliminated in lens mature fibers of Gja3(-/-) lenses, corresponding to nuclear cataracts. Cytoskeletal proteins including CP49 and periaxin act as genetic modifiers to modulate cataract severity of Gja3(-/-) mice in different strain backgrounds. In contrast, a loss of Cx50(Gja8) impairs the ball-and-socket structures of peripheral differentiating fiber cells to delay the fiber cell elongation nd disrupt lens homeostasis to lead to smaller lenses.
Specific aims of this project are designed to test our hypothesis that functional coordination between gap junctions and cytoskeletal components controls lens fiber-to-fiber interlocking structures, including protrusions on the short sides and ball-and-sockets on the long sides of hexagonal shaped fiber cells in lens cortex and the tongue/groove structures in mature fiber cells in the lens core.
Specific aim 1 will study how Cx46 (Gja3) gap junctions, CP49 and periaxin coordinately control fiber cell surface interlock structures to maintain lens integrity, homeostasis and transparency. We will further identify protein components associated with Cx46 (Gja3) gap junctions/cytoskeleton that are important for maintaining interlocking structures such as protrusions.
Specific aim 2 aims to elucidate the molecular basis for how Cx50 (Gja8) gap junctions establish ball-and-socket structures on the long sides of hexagonal shaped fiber cells needed for lens growth. We will identify specific PDZ-domain containing proteins that bind to the C-terminal ends of Cx50 and link to cytoskeleton for establishing ball-and-socket structures.
Specific aim 3 will identify and characterize the third genetic modifier on Chromosome 2, which can suppress the effect of 129-periaxin during cataractogenesis. We will further determine specific biochemical, physiological and biomechanical changes associated with nuclear cataracts.
The eye lens is a syncytial unit coupled by gap junctions; our vision depends on its optical and mechanical properties, such as transparency, refractive index, stiffness and accommodation. This proposal will evaluate a new hypothesis that these properties are achieved through the coordinated roles of gap junctions and cytoskeletal components during lens morphogenesis. Aging, genetic variances and other factors can trigger the pathological conditions in lens cells leading to cataracts, which remain as the leading cause of blindness in the world. Genetic variances of membrane/cytoskeletal proteins influence lens transparency and biomechanics. This research proposal will examine this new hypothesis and expand our knowledge of cataract etiology and prevention.
| Wang, Dong; Wang, Eddie; Liu, Kelsey et al. (2017) Roles of TGF? and FGF signals during growth and differentiation of mouse lens epithelial cell in vitro. Sci Rep 7:7274 |
| Wang, Eddie; Geng, Andrew; Seo, Richard et al. (2017) Knock-in of Cx46 partially rescues fiber defects in lenses lacking Cx50. Mol Vis 23:160-170 |
| Cheng, Catherine; Fowler, Velia M; Gong, Xiaohua (2017) EphA2 and ephrin-A5 are not a receptor-ligand pair in the ocular lens. Exp Eye Res 162:9-17 |
| Wang, Eddie; Geng, Andrew; Maniar, Ankur M et al. (2016) Connexin 50 Regulates Surface Ball-and-Socket Structures and Fiber Cell Organization. Invest Ophthalmol Vis Sci 57:3039-46 |
| Xia, Chun-hong; Liu, Haiquan; Cheung, Debra et al. (2015) NHE8 is essential for RPE cell polarity and photoreceptor survival. Sci Rep 5:9358 |
| Hitomi, Masahiro; Deleyrolle, Loic P; Mulkearns-Hubert, Erin E et al. (2015) Differential connexin function enhances self-renewal in glioblastoma. Cell Rep 11:1031-42 |
| Zhu, Yanan; Yu, Hao; Wang, Wei et al. (2014) A novel GJA8 mutation (p.V44A) causing autosomal dominant congenital cataract. PLoS One 9:e115406 |
| Xia, Chun-hong; Lu, Eric; Zeng, Jing et al. (2013) Deletion of LRP5 in VLDLR knockout mice inhibits retinal neovascularization. PLoS One 8:e75186 |
| Cheng, Catherine; Ansari, Moham M; Cooper, Jonathan A et al. (2013) EphA2 and Src regulate equatorial cell morphogenesis during lens development. Development 140:4237-45 |
| Liu, Zhenzhen; Taylor, Allen; Liu, Yizhi et al. (2012) Enhancement of ubiquitin conjugation activity reduces intracellular aggregation of V76D mutant ?D-crystallin. Invest Ophthalmol Vis Sci 53:6655-65 |
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