Keratins, Wound Reepithelialization, and Hair Follicle Cycling

描述（由申请人提供）：角蛋白是上皮细胞中丰富的蛋白质，它们以10- 12nm宽的中间丝（IPs）的细胞质网络的形式存在。它们是由哺乳动物中的一个保守基因大家族编码的，其中有50个个体成员分为两种序列类型。在纤维组装过程中，对I型和II型角蛋白异聚的严格要求是角蛋白基因疼痛/反向转录调控的基础。此外，个体对以组织类型和分化特异性的方式调节。阐明角蛋白多样性和差异分布背后的基本原理，为健康和疾病方面的上皮生物学提供了新的见解。角蛋白诱导多能蛋白作为有弹性且柔韧的支架，赋予上皮细胞承受机械和非机械应力的能力。改变角蛋白编码序列的遗传突变是几种上皮易碎性疾病的基础。此外，角蛋白IPs调节细胞对特定促凋亡信号的反应，控制细胞和组织生长，以及单层上皮中膜蛋白的路线。今年是该项目的第九年，该项目以角蛋白16和角蛋白17为中心，角蛋白16和角蛋白17在所有上皮附属物中都有组成性表达，在皮肤组织受到损伤、紫外线照射和其他挑战以及牛皮癣和皮肤癌等疾病时都会被诱导表达。在接下来的一段时间里，我们将重点关注皮肤上皮中含有K14-、K16-和k17的细丝的非机械功能，特别强调上皮细胞存活（目的1），通过调节蛋白质合成来控制上皮细胞生长（目的2），以及它们在体内的调节特性（目的3）。该建议主要来自于小鼠缺乏角蛋白17的相关后果，其导致毛基质上皮细胞过早凋亡继发的毛发循环缺陷，以及与伤口边缘活化上皮细胞较小有关的胚胎伤口闭合缺陷。由于角化蛋白16和新发现的角化蛋白17n的存在减轻了K17的零表型，我们还将生产一种小鼠菌株，使K7n-K17-K16基因簇的失活在时间和空间上受到控制（目的4）。因此，该项目将进一步加深我们对角蛋白在健康和疾病中的特性和功能的理解。

DESCRIPTION (provided by applicant): Keratins are abundant proteins in epithelial cells, in which they occur as a cytoplasmic network of 10-12 nm wide intermediate filaments (IPs). They are encoded by a large family of conserved genes in mammals, with > 50 individual members partitioned into two sequence types. A strict requirement for the heteropolymerization of type I and type II keratin proteins during filament assembly underlies the pain/vise transcriptional regulation of keratin genes. In addition, individual pairs are regulated in a tissue-type and differentiation- specific manner. Elucidating the rationale behind the diversity and differential distribution of keratin proteins offers the promise of novel insight into epithelial biology, in health and disease. Keratin IPs act as resilient yet pliable scaffolds that endow epithelial cells with the ability to sustain mechanical and non-mechanical stresses. Inherited mutations altering the coding sequence of keratins underlie several epithelial fragility conditions. In addition, keratin IPs modulate the cell's response to specific pro-apoptotic signals, control of cell and tissue growth, and the routing of membrane proteins in simple epithelia. Now it its ninth year, this project is centered around keratins 16 and 17, which are constitutively expressed in all epithelial appendages and induced whenever skin tissue is subjected to injury, UV exposure, and other challenges, as well as in diseases such as psoriasis and skin carcinoma. During the next period we will focus on the non-mechanical functions of K14-, K16- and K17-containing filaments in skin epithelia, with a particular emphasis on epithelial cell survival (Aim 1), control of epithelial cell growth through regulation of protein synthesis (Aim 2), and the characterization of their regulation in vivo (Aim 3). The proposal draws substantially from the consequences associated with lack of keratin 17 in mouse, which results in hair cycling defects secondary to the untimely apoptosis of hair matrix epithelial cells, and in embryonic wound closure defects correlating with smaller size of activated epithelial cell at the wound edge. Because the K17 null phenotype is mitigated by the presence of keratin16 and the newly discovered keratin17n, we will also produce a mouse strain enabling the temporally- and spatially-controlled inactivation of the K7n-K17-K16 gene cluster (aim 4). As such, the project will further our understanding of keratin properties and function in health and in disease.