Keratins are the forming units of intermediate filaments (IF) that provide mechanical support, and formation of desmosomes between cells and hemi desmosomes with basement membranes for epithelium integrity. Keratin IF are polymers of obligate heterodimer consisting one type I keratin and one type II keratin molecules. There are 54 functional keratin genes in human genome, which are classified into three major groups, i.e., epithelial keratins, hair follicle cell-specific epithelial keratins and hair keratins. Their expression is cell type-specific and developmentally regulated. Corneal epithelium expresses a subgroup of keratins similar to those of epidermal epithelium. Limbal basal stem cells express K5/K14, and K8/K18 and K8/K19 IF suggesting that there probably are two populations of limbal stem cells (LSCs). In human, LSCs at limbal basal layer can directly stratify and differentiate to limbal suprabasal cells that express K3/K12 IF, or centripetally migrate then differentiate to corneal basal transient amplifying cells (TAC) that co-express both K3/K12 and K5/K14 prior to moving upward and assuming suprabasal cells phenotype of only K3/K12 expression that signifies corneal type epithelium differentiation. In rodent, the differentiated cornea epithelial cells express K5/K12 in lieu of K3/K12, because K3 allele exists as a pseudogene and does not encode a functional K3 protein. The basal corneal cells of new-born mice originate from surface ectoderm during embryonic development slowly commit to differentiation of becoming TAC co-expressing K5/K12 and K5/K14 IF. However, the centripetal migration may still occur at a slower rate in young mice, which is accelerated during wound healing. In this review, we will discuss and compare the cornea–specific keratins expression patterns between corneal and epidermal epithelial cells during mouse development, and between human and mouse during development and homeostasis in adult, and pathology caused by a mutation of keratins.

角蛋白是提供机械支撑的中间丝（IF）的形成单位，以及在细胞和半桥基之间形成带有基膜的上皮完整性的半桥形成的桥粒。角蛋白IF是由一种I型角蛋白和一种II型角蛋白分子组成的专性异二聚体的聚合物。人类基因组中有54个功能性角蛋白基因，它们被分为三大类，即上皮角蛋白，毛囊细胞特异性上皮角蛋白和头发角蛋白。它们的表达是细胞类型特异性的，并且受发育调控。角膜上皮表达与表皮上皮相似的角蛋白亚组。角膜缘干细胞表达K5 / K14，K8 / K18和K8 / K19 IF，提示可能存在两个角膜缘干细胞（LSC）群体。在人类中 角膜基底层的LSC可以直接分层并分化为表达K3 / K12 IF的角膜上基底细胞，或向心迁移然后分化为在移动前共表达K3 / K12和K5 / K14的角膜基底瞬时扩增细胞（TAC）并假设只有基底膜上皮细胞的表型只有K3 / K12表达，这表示角膜型上皮分化。在啮齿动物中，分化的角膜上皮细胞表达K5 / K12代替K3 / K12，因为K3等位基因以假基因形式存在并且不编码功能性K3蛋白。新生小鼠的基础角膜细胞在胚胎发育过程中起源于表面外胚层，缓慢分化为TAC，共同表达K5 / K12和K5 / K14 IF。但是，向心迁移可能仍会以较慢的速度在年幼小鼠中发生，在伤口愈合过程中会加速。在这篇综述中，我们将讨论和比较在小鼠发育过程中角膜和表皮上皮细胞之间以及在成年人发育和体内稳态过程中人与小鼠之间角膜特异性角蛋白的表达模式，以及由角蛋白突变引起的病理。