Data_Sheet_1_Glia-Mediated Regenerative Response Following Acute Excitotoxic Damage in the Postnatal Squamate Retina.PDF

The retina is a complex tissue responsible for both detection and primary processing of visual stimuli. Although all vertebrate retinas share a similar, multi-layered organization, the ability to regenerate individual retinal cells varies tremendously, being extremely limited in mammals and birds when compared to anamniotes such as fish and amphibians. However, little is yet known about damage response and regeneration of retinal tissues in “non-classical” squamate reptiles (lizards, snakes), which occupy a key phylogenetic position within amniotes and exhibit unique regenerative features in many tissues. Here, we address this gap by establishing and characterizing a model of excitotoxic retinal damage in bearded dragon lizard (Pogona vitticeps). We particularly focus on identifying, at the cellular and molecular level, a putative endogenous cellular source for retinal regeneration, as diverse self-repair strategies have been characterized in vertebrates using a variety of retinal injury and transgenic models. Our findings reveal for the first time that squamates hold the potential for postnatal retinal regeneration following acute injury. Although no changes occur in the activity of physiologically active progenitors recently identified at the peripheral retinal margin of bearded dragon, two distinct successive populations of proliferating cells at central retina respond to neurotoxin treatment. Following an initial microglia response, a second source of proliferating cells exhibit common hallmarks of vertebrate Müller glia (MG) activation, including cell cycle re-entry, dedifferentiation into a progenitor-like phenotype, and re-expression of proneural markers. The observed lizard glial responses, although not as substantial as in anamniotes, appear more robust than the absent or neonatal-limited regeneration reported without exogenous stimulation in other amniotes. Altogether, these results help to complete our evolutionary understanding of regenerative potential of the vertebrate retina, and further highlight the major importance of glial cells in retinal regeneration. Furthermore, our work offers a new powerful vertebrate model to elucidate the developmental and evolutionary bases of retinal regeneration within amniotes. Such new understanding of self-repair mechanisms in non-classical species endowed with regenerative properties may help designing therapeutic strategies for vertebrate retinal diseases.

视网膜是一种复杂的组织，负责视觉刺激的检测和初级处理。尽管所有脊椎动物视网膜都具有相似的多层组织结构，但单个视网膜细胞的再生能力却存在巨大差异，与鱼类和两栖类等无羊膜动物相比，哺乳动物和鸟类在视网膜再生方面的能力极为有限。然而，关于“非典型”蜥蜴类爬行动物（如蜥蜴、蛇）视网膜组织的损伤反应和再生机制的了解甚少，这些爬行动物在羊膜动物系统进化中占据关键位置，并在许多组织中表现出独特的再生特性。本研究旨在填补这一空白，通过建立并描述一种鬣蜥（Pogona vitticeps）的兴奋性毒性视网膜损伤模型。我们特别关注在细胞和分子水平上识别潜在的内在细胞来源，以促进视网膜再生，因为多种脊椎动物的自我修复策略已在多种视网膜损伤和转基因模型中得到表征。我们的研究首次揭示，蜥蜴类动物在急性损伤后具有潜在的出生后视网膜再生能力。尽管在鬣蜥外围视网膜边缘最近发现的生理活性祖细胞的活性没有发生变化，但视网膜中央区域的两个连续增殖细胞群体对神经毒素治疗产生了反应。在初始的小胶质细胞反应之后，第二个增殖细胞来源表现出与脊椎动物穆勒细胞（MG）激活的共同特征，包括细胞周期重新进入、去分化为祖细胞样表型以及神经发生标记物的重新表达。观察到的蜥蜴胶质细胞反应，尽管不如无羊膜动物显著，但相较于其他羊膜动物在没有外源性刺激下的缺失或新生儿有限的再生，显得更为稳健。总之，这些结果有助于完善我们对脊椎动物视网膜再生潜力的进化理解，并进一步凸显胶质细胞在视网膜再生中的主要重要性。此外，我们的研究为阐明羊膜动物视网膜再生的发育和进化基础提供了一个新的强大脊椎动物模型。对具有再生特性的非典型物种的自我修复机制的这种新认识，可能有助于设计针对脊椎动物视网膜疾病的治疗方案。