Jiang Huimin, Foroozandeh Parisa, Kaplan Nihal, Xu Dan, Yang Wending, Qi Xiaolin, Nalbant Elif Kayaalp, Clutter Elwin D, Zhu Yongling, Xu Jian, Schipma Matthew John, Ren Ziyou, Peng Han
Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
Department of Ophthalmology, The Second Hospital of Anhui Medical University, Hefei, China.
FASEB J. 2025 May 31;39(10):e70648. doi: 10.1096/fj.202500783R.
Limbal epithelial stem cells (LESCs), located in the basal layer of the limbal epithelium, rarely proliferate under normal conditions. Upon proliferation, LESCs give rise to early transient amplifying (eTA) cells, which are thought to be morphologically and phenotypically indistinguishable from LESCs. Following corneal epithelial wounding, LESCs are activated to repair the corneal epithelium via expansion of eTA cells, a process crucial for maintaining corneal epithelial homeostasis and tissue transparency as well as essential for clear vision. To understand how this process is regulated, we conducted a single cell RNA sequencing assay of mouse corneal rims with and without injury and observed an expansion of the stem/eTA cell cluster after corneal injury. Interestingly, we found that Interferon Induced Transmembrane Protein 1 (IFITM1) was predominantly expressed in stem/eTA cells and was positively associated with such stem/eTA cell expansion after corneal wounding. In vivo knockdown of IFITM1 using an AAV (adeno-associated virus) vector significantly attenuated stem/eTA cell expansion and activation of stem/eTA cells to proliferate after mouse corneal wounding. In human limbal epithelial cell cultures, IFITM1 positively impacted the proliferation of stem/eTA cell-enriched limbal epithelial cells, contributing to expansion of the stem/eTA cell population. Such expansion was due, in part, to inhibition of OVOL1 (Ovo like zinc finger 1), a negative regulator of epithelial cell proliferation. These results provide key molecular insights into how stem cell activation and eTA cell expansion are regulated. Elucidating the IFITM1/OVOL1 pathway that governs stem/eTA cell proliferation not only deepens our knowledge of tissue homeostasis but also opens avenues for developing novel regenerative therapies.
角膜缘上皮干细胞（LESCs）位于角膜缘上皮的基底层，在正常情况下很少增殖。增殖时，LESCs会产生早期短暂扩增（eTA）细胞，这些细胞在形态和表型上被认为与LESCs无法区分。角膜上皮损伤后，LESCs被激活，通过eTA细胞的扩增来修复角膜上皮，这一过程对于维持角膜上皮稳态和组织透明度至关重要，也是清晰视力所必需的。为了了解这一过程是如何被调控的，我们对受伤和未受伤的小鼠角膜边缘进行了单细胞RNA测序分析，观察到角膜损伤后干细胞/eTA细胞簇的扩增。有趣的是，我们发现干扰素诱导跨膜蛋白1（IFITM1）主要在干细胞/eTA细胞中表达，并且与角膜损伤后这种干细胞/eTA细胞的扩增呈正相关。使用腺相关病毒（AAV）载体在体内敲低IFITM1可显著减弱小鼠角膜损伤后干细胞/eTA细胞的扩增以及干细胞/eTA细胞的增殖激活。在人角膜缘上皮细胞培养中，IFITM1对富含干细胞/eTA细胞的角膜缘上皮细胞的增殖有积极影响，有助于干细胞/eTA细胞群体的扩增。这种扩增部分是由于抑制了上皮细胞增殖的负调节因子OVOL1（类卵锌指蛋白1）。这些结果为干细胞激活和eTA细胞扩增的调控提供了关键的分子见解。阐明控制干细胞/eTA细胞增殖的IFITM1/OVOL1途径不仅加深了我们对组织稳态的认识，也为开发新型再生疗法开辟了道路。
