KERATINS, WOUND REEPITHELIZATION, AND HAIR FOLLICLE CYCLING

描述(申请人提供)：角蛋白是上皮细胞中丰富的蛋白质，它们以10-12纳米宽的中间丝(IP)的细胞质网络形式出现。它们是由哺乳动物的一个保守基因大家族编码的，有50个单独的成员被分成两种序列类型。在细丝组装过程中，对I型和II型角蛋白蛋白的异聚有严格的要求，这是角蛋白基因转录调控的基础。此外，个体对以组织类型和分化特有的方式进行调节。阐明角蛋白蛋白多样性和差异性分布背后的基本原理，为健康和疾病中的上皮生物学提供了新的见解。角蛋白IP作为弹性但柔韧的支架，赋予上皮细胞承受机械和非机械应力的能力。遗传突变改变了角蛋白的编码序列，是几种上皮脆性疾病的基础。此外，角蛋白IP调节细胞对特定促凋亡信号的反应，控制细胞和组织的生长，以及简单上皮中膜蛋白的路线选择。现在已经是第九个年头了，这个项目以角蛋白16和17为中心，角蛋白16和17在所有上皮性附件中结构性表达，每当皮肤组织受到损伤、紫外线照射和其他挑战时，以及在牛皮癣和皮肤癌等疾病中都会诱导。在接下来的一段时间里，我们将专注于含有K14、K16和K17的细丝在皮肤上皮细胞中的非机械功能，特别强调上皮细胞的存活(目标1)，通过调节蛋白质合成来控制上皮细胞的生长(目标2)，以及它们在体内的调节特性(目标3)。该建议主要借鉴了与小鼠缺乏角蛋白17相关的后果，角蛋白17导致继发于毛发基质上皮细胞过早凋亡的毛发循环缺陷，以及与伤口边缘激活的上皮细胞体积较小相关的胚胎伤口闭合缺陷。由于角蛋白16和新发现的角蛋白17n的存在缓解了K17缺失的表型，我们还将产生一种能够在时间和空间上控制K7n-K17-K16基因簇的失活的小鼠品系(Aim 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了解。

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.