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-神经突复合体、其他触觉传入和触觉敏感性的急剧丧失。触觉感知的缺陷被认为有助于姿势稳定性和握力的下降，以及由此导致的跌倒频率的增加，这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）躯体感觉受体的多样性和ii）机械感受性末端器官分散在整个皮肤中的事实。此外，关于负责维持感知轻触的细胞机械感受器（例如默克尔细胞）的更新的推定皮肤祖细胞群体的信息非常缺乏。默克尔细胞代表了一个成熟的神经内分泌谱系，存在于啮齿动物和人类的多毛皮肤表皮中的独特结构中，称为触摸圆顶（TD）。我们的实验室先前鉴定了一种新的角质形成细胞祖细胞群，其定位于TD中的默克尔细胞，称为TD祖细胞（TDPC），并且我们证明TDPC可以在再生条件和稳态下产生默克尔谱系。为了进一步探索TDPC在默克尔细胞稳态中的作用，我们在实验室中产生了BAC转基因小鼠模型Krt 17 CreERT 2，其选择性靶向表皮中的TDPC以表达他莫昔芬诱导的Cre重组酶，同时排除成熟的默克尔细胞。使用Krt 17 CreERT 2小鼠与其他Cre诱导的报告等位基因的组合，我们证明了i）TDPC是皮肤的永久居民，其单独负责维持默克尔谱系，和ii）TD内的整个成熟默克尔细胞库在年轻成人皮肤中每两个月翻转一次。这些初步的研究结果建立了Krt 17 CreERT 2小鼠作为一个很好的平台，以检查默克尔细胞的稳态可能会受到干扰，在老化的皮肤。本研究的主要目的是确定TDPCs祖细胞能力的下降是否是默克尔细胞-神经突复合体中与年龄相关的损失和触觉减弱的基础。为了实现我们的目的，我们将使用Krt 17 CreERT 2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，我们将移植年轻成人和老年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。这些研究对于理解我们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，随着年龄的增长，触觉会严重减弱。