Type Iv Collagen Alpha 6 Chain Is A Regulator Of Keratin 10 In Keratinization Of Oral Mucosal Epithelium

Keratinized mucosa is of fundamental importance to maintain healthy gingival tissue, and understanding the mechanisms of oral mucosa keratinization is crucial to successfully manage healthy gingiva. Previous studies have shown a strong involvement of the basement membrane in the proliferation and differentiation of epithelial cells. Therefore, first, to identify the keratinized mucosa-specific basement membrane components, immunohistochemical analysis for the six alpha chains of type IV collagen was performed in 8-week-old mice. No difference in the expression pattern of type IV collagen alpha 1(IV) and alpha 2(IV) chains was observed in the keratinized and non-keratinized mucosa. Interestingly, however, type IV collagen alpha 5(IV) and alpha 6(IV) chains specifically were strongly detected in the keratinized mucosa. To analyze the functional roles of the type IV collagen isoform alpha 6(IV) in oral mucosa keratinization, we analyzed Col4a6-knockout mice. Epithelial developmental delay and low levels of KRT10 were observed in new-born Col4a6-knockout mice. Additionally, in vitro experiments with loss-of function analysis using human gingival epithelial cells confirmed the important role of a6(IV) chain in epithelial keratinization. These findings indicate that alpha 112: alpha 556 (IV) network, which is the only network that includes the alpha 6(IV) chain, is one regulator of KRT10 expression in keratinization of oral mucosal epithelium.