Ready Donald F, Chang Henry C
Department of Biological Sciences, Purdue University, 915 Mitch Daniels Boulevard, West Lafayette, IN 47907-2054, USA.
iScience. 2025 May 22;28(6):112732. doi: 10.1016/j.isci.2025.112732. eCollection 2025 Jun 20.
Visual acuity in requires precise photoreceptor alignment along the optical axis, maintained by longitudinal tension between a rigid cornea and a contractile retinal base. Here, we identify the rhabdomere caps-an extracellular matrix (ECM) structure that links rhabdomere tips to the integrin-decorated basal surfaces of overlying, lens-forming cone cells. Rhabdomere caps form perlecan-filled peaks shaped by a trapezoidal LanB1 (laminin) grid, which mirrors the inter-rhabdomeral space (IRS) contour. Our study revealed that Eys (), a photoreceptor-secreted proteoglycan essential for IRS formation, guides LanB1 and perlecan deposition by cone cells during pupal development. Disruption of LanB1 results in rhabdomere tip detachment, IRS collapse, and impaired tension transmission. These findings reveal that cone cells and photoreceptors collaboratively sculpt a rigid LanB1 grid that caps and reinforces the distal IRS lumen. This composite ECM structure preserves rhabdomere organization and evenly distributes mechanical forces, ensuring photoreceptor alignment and optical fidelity.
视力需要精确的光感受器沿光轴排列，这是由刚性角膜和收缩性视网膜基部之间的纵向张力维持的。在这里，我们鉴定出了视小杆帽——一种细胞外基质（ECM）结构，它将视小杆尖端与覆盖其上的形成晶状体的视锥细胞的整合素修饰的基底表面相连。视小杆帽形成由梯形LanB1（层粘连蛋白）网格塑造的富含基底膜聚糖的峰，该网格反映了视小杆间间隙（IRS）的轮廓。我们的研究表明，Eys（一种对IRS形成至关重要的光感受器分泌的蛋白聚糖）在蛹发育过程中引导视锥细胞沉积LanB1和基底膜聚糖。LanB1的破坏会导致视小杆尖端脱离、IRS塌陷以及张力传递受损。这些发现揭示，视锥细胞和光感受器共同塑造了一个刚性的LanB1网格，该网格覆盖并加强了远端IRS管腔。这种复合ECM结构保留了视小杆的组织并均匀分布机械力，确保光感受器排列和光学保真度。
