A non-cell-autonomous actin redistribution enables isotropic retinal growth

Tissue shape is often established early in development and needs to be scaled isotropically during growth. However, the cellular contributors and ways by which cells interact tissue-wide to enable coordinated isotropic tissue scaling are not yet understood. Here, we follow cell and tissue shape changes in the zebrafish retinal neuroepithelium, which forms a cup with a smooth surface early in development and maintains this architecture as it grows. By combining 3D analysis and theory, we show how a global increase in cell height can maintain tissue shape during growth. Timely cell height increase occurs concurrently with a non-cell-autonomous actin redistribution. Blocking actin redistribution and cell height increase perturbs isotropic scaling and leads to disturbed, folded tissue shape. Taken together, our data show how global changes in cell shape enable isotropic growth of the developing retinal neuroepithelium, a concept that could also apply to other systems.

组织形态通常在发育早期确立，并需在生长过程中实现各向同性缩放。然而，目前尚不明确细胞的具体贡献机制，以及细胞如何通过组织全局层面的相互作用，实现协同的各向同性组织缩放。本研究追踪了斑马鱼视网膜神经上皮（zebrafish retinal neuroepithelium）中的细胞与组织形态变化：该结构在发育早期形成表面光滑的杯状架构，并在后续生长过程中始终维持这一形态。通过结合三维分析与理论建模，我们阐明了细胞高度的整体增加如何在生长过程中维持组织形态。适时的细胞高度增加与非细胞自主性的肌动蛋白（actin）重分布同步发生。阻断肌动蛋白重分布与细胞高度增加，会扰乱各向同性缩放过程，并导致组织形态出现异常折叠。综上，本研究数据揭示了细胞形态的整体变化如何助力发育中的视网膜神经上皮实现各向同性生长，这一理论或可推广应用至其他研究系统。