第1114回生物科学セミナー

Stem cells in the neural retina set the pace of eye growth and shape

Prof. Joachim Wittbrodt(Centre for Organismal Studies, COS, Heidelberg University)

2016年09月27日(火)    13:30-15:00  理学部2号館 201号室   

The continuously growing eye of fish presents the perfect model system to explore how different tissues coordinate proliferation in an organ. The neural retina and surrounding retinal pigmented epithelium (RPE) share a bipartite stem cell niche. Strikingly, labeling the progeny of individual stem cells in medaka (Oryzias latipes) reveals heterogeneous lineages that differ between neural retina and RPE. Why do these tissues grow differently, and how can heterogeneous lineages be reconciled with homogeneous organ growth? To answer these questions, we simulate a 3D virtual eye in a computational cell-based model implemented in the platform EPISIM.
In the virtual eye, a monolayer of spherical cells is affixed to an expanding hemispherical surface. Cells only proliferate within a narrow ring at the base of the hemisphere; divisions occur with a random chance. This model shows that distinct clonal patterns in neural retina and RPE arise due to different growth modes: Cells in the RPE passively proliferate in response to an expanding caffold, whereas neural retinal cells control organ growth pace. Moreover, neural retinal stem cells in vivo preferentially choose a biased division axis that hints at a role in regulating eye shape. By exploring various proliferation and growth modes, the model highlights a role of the retina in controlling eye growth, eye shape, and retinal architecture. By tweaking these parameters, evolution can alibrate the eye to perfectly adapt to the animal’s ecological niche.