Suzuki Ken-ichi, Utoh Rie, Kotani Kaori, Obara Masanobu, Yoshizato Katsutoshi
Developmental Biology Laboratory, Department of Biological Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima 739-8526, Japan.
Dev Growth Differ. 2002 Jun;44(3):225-38. doi: 10.1046/j.1440-169x.2002.00637.x.
The anuran remodels the larval epidermis into the adult one during metamorphosis. Larval and adult epidermal cells of the bullfrog were characterized by determining the presence of huge cytoplasmic keratin bundles and the expression profiles of specific marker genes, namely colalpha1 (collagen alpha1 (I)), rlk (larval keratin) and rak (adult keratin). We identified four types of epidermal basal cells: (i) basal skein cells that have keratin bundles and express colalpha1 and rlk; (ii) rak+-basal skein cells that have keratin bundles and express colalpha1, rlk, and rak; (iii) larval basal cells that express rlk and rak; and (iv) adult basal cells that express rak. These traits suggested that these basal cells are on the same lineage in which basal skein cells are the original progenitor cells that consecutively differentiate into rak+-basal skein cells into larval basal cells, and finally into adult basal cells. To directly verify the differentiation potential of larval basal cells into adult ones, the mono-layered epidermis composed of larval basal cells was cultured in the presence of aldosterone and thyroid hormone. In this culture, larval basal cells differentiated into adult basal cells that reconstituted the adult epidermis. Thus, it was concluded that larval basal cells are the direct progenitor cells of the adult epidermal stem cells.
无尾两栖类在变态过程中将幼体表皮重塑为成体表皮。通过确定巨大的细胞质角蛋白束的存在以及特定标记基因即Ⅰ型胶原α1（colalpha1）、幼体角蛋白（rlk）和成体角蛋白（rak）的表达谱，对牛蛙的幼体和成体表皮细胞进行了表征。我们鉴定出四种类型的表皮基底细胞：（i）具有角蛋白束并表达colalpha1和rlk的基底绞链细胞；（ii）具有角蛋白束并表达colalpha1、rlk和rak的rak +基底绞链细胞；（iii）表达rlk和rak的幼体基底细胞；以及（iv）表达rak的成体基底细胞。这些特征表明，这些基底细胞处于同一谱系，其中基底绞链细胞是原始祖细胞，其依次分化为rak +基底绞链细胞、幼体基底细胞，最终分化为成体基底细胞。为了直接验证幼体基底细胞向成体基底细胞的分化潜能，在醛固酮和甲状腺激素存在的情况下培养由幼体基底细胞组成的单层表皮。在这种培养中，幼体基底细胞分化为重建成体表皮的成体基底细胞。因此，得出结论，幼体基底细胞是成体表皮干细胞的直接祖细胞。
