A cellular basis for age-related impaired tactile acuity

与年龄相关的触觉敏锐度受损的细胞基础

• 批准号: 8638126
• 负责人: DAVID M OWENS
• 金额: $ 24万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-01-15 至 2015-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8638126
• 关键词: 2 year old; Address; Age; Aging; Alleles; Apoptosis; Behavior; Biological Assay; Cell Aging; Cell physiology; Cells; Cellular biology; Cleaved cell; Complex; Cutaneous; Defect; Deterioration; Eating; Elderly; Elements; Epidermis; Frequencies; Future; Genetic; Goals; Hand; Homeostasis; Hour; Human; Implant; In Vitro; Laboratories; Life; Light; Mechanoreceptors; Mediating; Merkel Cells; Mitotic; Molecular; Mus; Natural regeneration; Nerve; Neurites; Neurosecretory Systems; Organ; Perception; Physiologic pulse; Play; Population; Quality of life; Reporter; Research Design; Rodent; Role; Sensory; Signal Pathway; Skin; Skin Aging; Somatosensory Receptor; Sorting - Cell Movement; Stem cells; Structure; Tactile; Tamoxifen; Testing; Time; Touch sensation; Transgenic Mice; Transplantation; age group; age related; aged; base; caspase-3; cell age; cell growth regulation; design; falls; grasp; in vivo; keratinocyte; mouse model; novel; progenitor; public health relevance; receptor; recombinase; reconstitution; regenerative; response; sound; success; therapeutic target; tool; young adult

DESCRIPTION (provided by applicant): It is well established that touch perception deteriorates with age and this phenomenon is accompanied by a number of structural defects in the skin including a dramatic loss of Merkel cell-neurite complexes, other tactile afferents and touch sensitivity. Deficits in touch perception are thought to contribute to the decline of postura stability and handgrip, and the resulting increase in falling frequency, which is a major factor determining quality of life and the ability to live independently for the elderly. Technical hurdle that have hindered efforts to understand the cellular and molecular basis of age-related losses in touch perception are i) the variety of somatosensory receptors and ii) the fact that mechanoreceptive end organs are scattered throughout the skin. Furthermore, information regarding putative skin progenitor populations that are responsible for maintaining the turnover of cellular mechanoreceptors that perceive light touch, such as Merkel cells, is sorely lacking. Merkel cells represent a mature neuroendocrine lineage that resides in unique structures in the epidermis of hairy skin in rodents and humans termed touch domes (TDs). Our laboratory previously identified a novel keratinocyte progenitor population localized with Merkel cells in TDs termed TD progenitor cells (TDPCs) and we demonstrated that TDPCs could give rise to the Merkel lineage both under regenerative conditions and homeostasis. To further explore the role of TDPCs in Merkel cell homeostasis, we generated a BAC transgenic mouse model in our laboratory, Krt17CreERT2 that selectively targets TDPCs in the epidermis for expression of a tamoxifen-inducible Cre recombinase while excluding mature Merkel cells. Using Krt17CreERT2 mice in combination with other Cre-inducible reporter alleles we demonstrated that i) TDPCs are permanent residents of the skin that are solely responsible for maintaining the Merkel lineage and ii) the entire pool of mature Merkel cells within the TD is turned over every two months in young adult skin. These preliminary findings establish Krt17CreERT2 mice as an excellent platform to examine how Merkel cell homeostasis may be perturbed in aged skin. The main objective of this proposal is to determine whether a decline in progenitor capacity of TDPCs underlies the age-related loss in Merkel cell-neurite complexes and diminished touch sensation. To accomplish our objective, we will employ Krt17CreERT2 mice to determine the rate of Merkel cell genesis and apoptosis in aged skin. We will also purify TDPCs from aged skin and assess their clonogenic capacity in vitro. Finally, we will transplant young adult and aged TDPCs and directly assess their ability to regenerate Merkel cells in vivo and restore tactile acuity. These studies will be critical to understanding the cellular regulation of our sense of touch, an essentil element of our ability to perceive our surroundings that is severely diminished as we age.

描述（由申请人提供）：众所周知，触觉感知会随着年龄的增长而恶化，并且这种现象伴随着皮肤中的许多结构缺陷，包括默克尔细胞神经突复合物、其他触觉传入和触觉敏感性的急剧丧失。触觉感知缺陷被认为会导致姿势稳定性和握力下降，从而导致跌倒频率增加，而跌倒频率是决定老年人生活质量和独立生活能力的主要因素。阻碍理解与年龄相关的触觉损失的细胞和分子基础的技术障碍是 i) 体感受体的多样性和 ii) 机械感受终末器官分散在整个皮肤的事实。此外，关于假定的皮肤祖细胞群的信息非常缺乏，这些祖细胞群负责维持感知光触的细胞机械感受器（例如默克尔细胞）的更新。默克尔细胞代表了一种成熟的神经内分泌谱系，存在于啮齿动物和人类毛状皮肤表皮的独特结构中，称为触摸圆顶（TD）。我们的实验室之前发现了一种新的角质形成细胞祖细胞群，其位于 TD 中的默克尔细胞中，称为 TD 祖细胞 (TDPC)，并且我们证明 TDPC 在再生条件和稳态下都可以产生默克尔谱系。为了进一步探讨 TDPC 在 Merkel 细胞稳态中的作用，我们在实验室中构建了 BAC 转基因小鼠模型 Krt17CreERT2，该模型选择性地靶向表皮中的 TDPC 以表达他莫昔芬诱导的 Cre 重组酶，同时排除成熟的 Merkel 细胞。使用 Krt17CreERT2 小鼠与其他 Cre 诱导的报告等位基因相结合，我们证明了 i) TDPC 是皮肤的永久居民，仅负责维持 Merkel 谱系，并且 ii) TD 内的整个成熟 Merkel 细胞库每更新一次年轻成人皮肤两个月。这些初步研究结果表明，Krt17CreERT2 小鼠是一个绝佳的平台，可用于研究老化皮肤中默克尔细胞稳态如何受到干扰。该提案的主要目的是确定 TDPC 祖细胞能力的下降是否是与年龄相关的默克尔细胞神经突复合物损失和触觉减弱的基础。为了实现我们的目标，我们将使用 Krt17CreERT2 小鼠来确定老化皮肤中默克尔细胞发生和凋亡的速率。我们还将从老化皮肤中纯化 TDPC，并评估其体外克隆形成能力。最后，我们将移植年轻和老年的TDPC，并直接评估它们在体内再生默克尔细胞和恢复触觉敏锐度的能力。这些研究对于理解触觉的细胞调节至关重要，触觉是我们感知周围环境的能力的一个基本要素，但随着年龄的增长，触觉会严重减弱。