Investigating the role for Utrophin in age-related decline of the Merkel lineage

研究 Utropin 在默克尔谱系年龄相关衰退中的作用

• 批准号: 10289985
• 负责人: DAVID M OWENS
• 金额: $ 32.82万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10289985
• 关键词: Address; Adult; Age; Age-Months; Age-Years; Aging; Alleles; Apoptosis; Behavior; Cell Count; Cell Lineage; Cell Maintenance; Cell Survival; Cells; Cellular biology; Cutaneous; Data; Defect; Development; ERBB2 gene; Eating; Elderly; Epithelial; Etiology; Focal Adhesions; Frequencies; Future; Genetic; Goals; Hand; Homeostasis; Human; In Vitro; Label; Laboratories; Ligands; Maintenance; Mammals; Measures; Mechanoreceptors; Mediator of activation protein; Merkel Cells; Messenger RNA; Molecular; Morphogenesis; Morphology; Mus; Organ; Pathway interactions; Physiologic pulse; Physiological; Population; Posture; Property; Proteins; Proteomics; Quality of life; Regulation; Reporter; Research Design; Rodent; Role; Sensory; Signal Pathway; Signal Transduction; Skin; Skin Aging; Source; Structure; Tactile; Tamoxifen; Testing; Texture; Touch sensation; Transgenic Mice; Transgenic Organisms; Utrophin; age related; aged; epithelial stem cell; falls; genetic approach; grasp; in vivo; keratinocyte; mouse model; mutant; nerve supply; postnatal; receptor; response; senescence; somatosensory; sound; stem cell function; stem cells; tool; transcriptome; translational study; vibration

Our sense of touch enables numerous behaviors fundamental to human existence, allowing us to eat, communicate and survive. Deficits in tactile responsiveness are thought to contribute to the decline of postural stability and hand grip, 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. In mammals, different tactile qualities (curvature, texture and vibration) are encoded by touch receptors residing in the skin with distinct physiological properties and morphological end-organs; however, the cellular and molecular mechanisms underlying this diversity are largely unknown. Furthermore, the regulation of skin stem cells that are responsible for maintaining the turnover of cellular mechanoreceptors that perceive gentle touch, such as Merkel cells, is unknown. Our laboratory previously characterized a population of epithelial stem cells that reside in epidermal touch domes in the skin, termed touch dome stem cells (TDSCs), that are responsible for maintaining the Merkel lineage during homeostasis. The long-term goal of this proposal is to define the cellular and molecular basis for TDSC maintenance of the Merkel lineage. Our preliminary data chronicles a dramatic age-related decline in Merkel cell numbers in human (40 – 90 years of age) and murine (2 – 32 months of age) skin. However, TDSC numbers remain unchanged. We confirmed that age-related loss of Merkel cells is not due to precocious exit of mature Merkel cells or defects in sensory afferent innervation but is due to diminished TDSC progenitor capacity to replenish the Merkel lineage. Leveraging this age-related deficit in TDSC progenitor capacity, we performed proteomics and mRNA profiling of TDSCs from young versus aged mouse skin and identified the focal adhesion-associated protein Utrophin (Utrn) to be dramatically downregulated in aged TDSCs. Utrn null (Utrn-/-) mice at postnatal day 20 displayed equal numbers of Merkel cells compared to Wt mice, excluding a role for Utrn in Merkel cell development. However, Merkel cell numbers were reduced by 50% in 2-month-old Utrn-/- mice providing genetic evidence for a functional role for Utrn in age-related maintenance of the Merkel lineage by TDSCs. We identified the Nrg1-Erbb2 signaling axis as a regulator of Utrn expression in mouse and human epithelial keratinocytes in vitro and TDSCs in vivo. These preliminary findings support our central hypothesis: Nrg1-Erbb2 regulation of Utrn expression is required for TDSC maintenance of Merkel cell homeostasis. To test our hypothesis, we will employ mouse models to genetically disrupt or rescue Utrn expression and assess its impact on Merkel cell homeostasis. Using in vivo lineage tracing tools and a Nrg1 conditional allele we will investigate the cellular mechanisms underlying TDSC maintenance of the Merkel lineage and upstream regulation of Nrg1 expression in the TD niche. Finally, we will interrogate the molecular mechanisms for Utrn regulation and downstream effectors of Utrn function in TDSCs. Our goal is to uncover first of its kind genetic mechanisms for stem cell regulation of the Merkel lineage.

我们的触觉使人类生存的许多基本行为成为可能，使我们能够吃饭、 触觉反应能力的缺陷被认为是导致姿势下降的原因。 稳定性和握力，以及由此导致的跌倒频率的增加，这是决定的主要因素 老年人的生活质量和独立生活的能力在哺乳动物中具有不同的触觉品质。 （曲率、纹理和振动）由皮肤中的触觉感受器编码，具有不同的生理特征 特性和形态终末器官；然而，其背后的细胞和分子机制 此外，负责皮肤干细胞的调节在很大程度上是未知的。 维持感知轻柔触摸的细胞机械感受器（例如默克尔细胞）的更新是 我们的实验室之前对存在于表皮中的上皮干细胞群进行了表征。 皮肤中的触摸穹顶，称为触摸穹顶干细胞 (TDSC)，负责维持 稳态期间的默克尔谱系 该提案的长期目标是定义细胞和分子。 我们的初步数据记录了与年龄相关的戏剧性事件。 人类（40 – 90 岁）和小鼠（2 – 32 个月大）皮肤中默克尔细胞数量下降。 然而，TDSC 数量保持不变，我们证实与年龄相关的默克尔细胞损失并不是由于。 成熟默克尔细胞过早退出或感觉传入神经支配缺陷，但归因于 TDSC 减少 利用 TDSC 祖细胞中与年龄相关的缺陷来补充 Merkel 谱系的祖细胞能力。 为了提高能力，我们对年轻人和小鼠皮肤的 TDSC 进行了蛋白质组学和 mRNA 分析， 发现粘着斑相关蛋白 Utropin (Utrn) 在老年人中显着下调 TDSC。Utrn null (Utrn-/-) 小鼠在出生后第 20 天显示出与 Wt 相同数量的 Merkel 细胞。 小鼠，排除了 Utrn 在 Merkel 细胞发育中的作用。然而，Merkel 细胞数量减少了。 2 个月大的 Utrn-/- 小鼠中的 50% 为 Utrn 在年龄相关中的功能作用提供了遗传证据 我们确定 Nrg1-Erbb2 信号轴是 TDSC 维持 Merkel 谱系的调节因子。 Utrn 在体外小鼠和人上皮角质形成细胞以及体内 TDSC 中的表达。 研究结果支持我们的中心假设：TDSC 需要 Nrg1-Erbb2 对 Utrn 表达的调节 为了检验我们的假设，我们将采用小鼠模型进行遗传研究。 使用体内谱系破坏或挽救 Utrn 表达并评估其对默克尔细胞稳态的影响。 追踪工具和 Nrg1 条件等位基因，我们将研究 TDSC 的细胞机制 最后，我们将讨论 TD 生态位中 Merkel 谱系的维持和 Nrg1 表达的上游调节。 探究 TDSC 中 Utrn 调节和 Utrn 功能下游效应器的分子机制。 我们的目标是首次揭示默克尔谱系干细胞调控的遗传机制。