Department of Dermatology, Medical University of Vienna, Vienna, Austria.
Department of Medical Biochemistry, Medical University of Vienna, Vienna, Austria.
Sci Rep. 2022 Jan 7;12(1):126. doi: 10.1038/s41598-021-04082-1.
The growth of skin appendages, such as hair, feathers and scales, depends on terminal differentiation of epidermal keratinocytes. Here, we investigated keratinocyte differentiation in avian scutate scales. Cells were isolated from the skin on the legs of 1-day old chicks and subjected to single-cell transcriptomics. We identified two distinct populations of differentiated keratinocytes. The first population was characterized by mRNAs encoding cysteine-rich keratins and corneous beta-proteins (CBPs), also known as beta-keratins, of the scale type, indicating that these cells form hard scales. The second population of differentiated keratinocytes contained mRNAs encoding cysteine-poor keratins and keratinocyte-type CBPs, suggesting that these cells form the soft interscale epidermis. We raised an antibody against keratin 9-like cysteine-rich 2 (KRT9LC2), which is encoded by an mRNA enriched in the first keratinocyte population. Immunostaining confirmed expression of KRT9LC2 in the suprabasal epidermal layers of scutate scales but not in interscale epidermis. Keratinocyte differentiation in chicken leg skin resembled that in human skin with regard to the transcriptional upregulation of epidermal differentiation complex genes and genes involved in lipid metabolism and transport. In conclusion, this study defines gene expression programs that build scutate scales and interscale epidermis of birds and reveals evolutionarily conserved keratinocyte differentiation genes.
皮肤附属物（如毛发、羽毛和鳞片）的生长依赖于表皮角质形成细胞的终末分化。在这里，我们研究了鸟类片状鳞片中的角质形成细胞分化。我们从 1 日龄小鸡腿部的皮肤中分离出细胞，并进行单细胞转录组学分析。我们鉴定出两种不同的分化角质形成细胞群体。第一群体的特征是编码富含半胱氨酸的角蛋白和角蛋白 β-蛋白（CBPs），也称为β-角蛋白，属于鳞片类型，表明这些细胞形成硬鳞片。第二群体的分化角质形成细胞含有编码半胱氨酸贫乏的角蛋白和角质形成细胞型 CBPs 的 mRNA，表明这些细胞形成柔软的鳞片间表皮。我们制备了针对富含半胱氨酸的角蛋白 9 样 2（KRT9LC2）的抗体，该蛋白由在第一角质形成细胞群体中富集的 mRNA 编码。免疫染色证实 KRT9LC2 在片状鳞片的棘层表皮层中表达，但不在鳞片间表皮中表达。鸡腿部皮肤中的角质形成细胞分化与人类皮肤相似，表现为表皮分化复合体基因和参与脂质代谢和转运的基因的转录上调。总之，这项研究定义了构建鸟类片状鳞片和鳞片间表皮的基因表达程序，并揭示了进化上保守的角质形成细胞分化基因。
