A Human Model for Telomerase Dysfunction and Aging

描述（由申请人提供）：端粒缩短是衰老的自然结果，端粒酶功能障碍最近与某些与高增殖组织（包括表皮）缺陷相关的疾病有关。我们的长期目标是了解端粒酶和端粒长度在调节人类皮肤功能和衰老中的作用。先天性角化不良（DC）是一种遗传性“早衰”综合征，其特征是表皮异常（如白斑、皮肤色素沉着、脱发）和器官功能障碍（如骨髓衰竭、肺纤维化）。DC是由影响端粒酶活性的基因突变引起的，导致体细胞端粒缩短。我们最近发现了这种疾病的常染色体显性形式（AD DC），这是由于端粒酶的RNA成分hTERC的缺失。AD DC为研究端粒酶和端粒缩短在衰老生物学中的调节作用提供了一个独特的人体模型系统。我们认为端粒酶和端粒长度是正常角质细胞功能、分化和应激反应的重要调节因子。此外，我们假设皮肤老化与端粒长度缩短和端粒酶成分表达失调有关。使用从AD DC受试者、正常对照和实验处理的细胞中分离的皮肤角质形成细胞和成纤维细胞，我们将进一步确定端粒酶和端粒长度在调节DNA损伤和氧化应激反应途径中的作用。我们将确定将端粒酶组分hTERC和/或hTERT引入AD DC细胞是否能恢复复制潜力、细胞功能以及对应激和DNA损伤的正常反应。我们还将探索hTERT在角化细胞中超越端粒维持的功能的可能性，并进行研究以确定异常长的端粒相关的hTERC和hTERT的共表达是否对细胞表型有任何影响。总的来说，本应用中提出的实验将进一步加深我们对端粒酶和端粒在与衰老相关的细胞缺陷中的作用的理解，并为控制正常皮肤功能和衰老的过程提供关键的机制见解。重要的是，这些发现还可能促进旨在减少衰老对人类皮肤和其他组织影响的新策略的发展，并改善老年人癌症治疗的毒性。

DESCRIPTION (provided by applicant): Telomere shortening, a natural consequence of aging, and telomerase dysfunction have recently been linked with certain diseases associated with defects in highly proliferative tissue, including the epidermis. Our long-term goal is to understand the contribution of telomerase and telomere length in regulating the function and aging of human skin. Dyskeratosis congenita (DC) is an inherited "premature aging" syndrome characterized by epidermal abnormalities (e.g. leukoplakia, skin hypopigmentation, alopecia) and organ dysfunction (e.g. bone marrow failure, pulmonary fibrosis). DC is caused by mutations in genes that affect telomerase activity, resulting in shortening of telomeres in somatic cells. We recently identified an autosomal dominant form of this disease (AD DC) that is due to a deletion in hTERC, the RNA component of telomerase. AD DC provides a unique human model system to study the regulatory role of telomerase and telomere shortening in the biology of aging. We propose that telomerase and telomere length are important regulators of normal keratinocyte function, differentiation, and response to stress. Furthermore, we hypothesize that skin aging is associated with telomere length shortening and dysregulation of telomerase component expression. Using skin keratinocytes and fibroblasts isolated from AD DC subjects, normal controls and experimentally manipulated cells, we will further define the role of telomerase and telomere length in regulating DNA damage and oxidative stress response pathways. We will determine whether introduction of telomerase components, hTERC and/or hTERT, into AD DC cells restores replicative potential, cellular function, and normal responses to stress and DNA damage. We will also explore the possibility that hTERT has functions in keratinocytes that go beyond telomere maintenance and perform studies to determine whether the unusually long telomeres associated co-expression of hTERC and hTERT have any effects on cell phenotype. Overall, the experiments proposed in this application will further our understanding of the role of telomerase and telomeres in cellular defects associated with aging, and provide critical mechanistic insights into the processes that govern normal skin function and aging. Importantly, these findings may also promote the development of novel strategies aimed at reducing the effects of aging on human skin and other tissues, and in ameliorating the toxicity of cancer therapies in the elderly.