Role of p21 positive senescent cells in radiation-induced skeletal injury and repair

p21阳性衰老细胞在辐射引起的骨骼损伤和修复中的作用

• 批准号: 10711159
• 负责人: Abhishek Chandra
• 金额: $ 40.35万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2028-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10711159
• 关键词: AP20187; Acute; Adipocytes; Adverse event; Affect; Aging; Apoptosis; Architecture; Biological Markers; Biology of Aging; Bone Marrow; Bone Marrow Cells; CDKN2A gene; Cancer Survivor; Caspase; Cell Aging; Cells; Chronic; Clinical Research; Cre-LoxP; Crossbreeding; Cyclin-Dependent Kinase Inhibitor; Cytometry; DNA Damage; Dasatinib; Data; Deterioration; Early Intervention; Elderly; Environment; Enzymes; Excision; Fibrosis; Fracture; Functional disorder; Gene Expression; Gene Expression Profile; Generations; Genetic; Growth; Growth Factor; Hematopoietic; ITGAM gene; In Situ Hybridization; Independent Living; Inflammatory; Knowledge; LOX gene; Mediating; Mesenchymal; Mouse Strains; Mus; Myeloid Cells; Nature; Osteoblasts; Osteocytes; Osteogenesis; Osteoporosis; Oxidative Stress; Pathway interactions; Patients; Pattern; Phenotype; Physiological; Plasma; Population; Proteins; Quality of life; Quercetin; RNA; Radiation; Radiation therapy; Risk Reduction; Role; Seminal; Stromal Cells; Testing; Time; Transgenes; Transgenic Mice; Visualization; Work; aged; biomarker identification; bone; bone cell; bone fracture repair; cell type; chemokine; cytokine; fracture risk; functional restoration; healing; injury and repair; long term recovery; novel; pharmacologic; phenotypic biomarker; prevent; regenerative; response; senescence; skeletal; skeletal injury; stem; stressor; theories; therapeutic target

Project Summary/Abstract Skeletal deterioration and related fracture risk is exacerbated in the elderly cancer survivors receiving radiation treatment (RTx), affecting independent living, and reducing quality of life. Cellular senescence, one of the major pathways induced following RTx-induced DNA damage, is characterized by a pro-inflammatory senescence associated secretory phenotype (SASP, consisting of chemokines, cytokines, growth factors, matrix degrading enzyme, etc), and is mainly regulated by cyclin dependent kinase inhibitors (CDKi’s) p16Ink4a and p21Cip1. Till recently, it was understood that p16Ink4a and p21Cip1 co-expressed in all senescent cells and regulated their function interchangeably. This theory however did not match with the expression pattern of p16Ink4a and p21Cip1 post-RTx or in aging. Using gene expression and RNA in situ hybridization studies, we have recently shown that cells express p21 or p16Ink4a in unique populations of bone marrow cells, osteoblasts, and osteocytes independent of the expression of either senescence marker. Only a small proportion of cells express both p16Ink4a and p21Cip1. Furthermore, we have compelling preliminary data using mass cytometry of bone cells, which allowed us to visualize these independent unique populations of p16Ink4a and p21Cip1 expressing cells without any coexpression of SASP, suggesting a physiological function of these CDKis. Interestingly, in a parallel analysis in radiated bones, we identified elevated levels of Cd11b+p21+ myeloid cell population, which was accompanied by expression of several SASP factors, thus allowing us to characterize these p21+ cells as p21+ senescent (p21+SEN) cells. In a recent seminal finding, using transgenic mice harboring transgenes that enable the selective elimination of either p16Ink4a or p21Cip1 expressing cells, the elimination of p21+SEN cells in the p21-ATTAC [apoptosis through targeted activation of caspase] mice, but not the elimination of p16+SEN cells in the p16-INK- ATTAC mice, could mitigate most of the RTx-related adverse events in bone in young mice. Whether this approach of clearance of p21+SEN cells will work to alleviate RTx-related bone deterioration in old mice, which have a pre-existing high burden of senescent cells, remains to be seen. Based on our compelling preliminary data, we will test our central hypothesis that: “Acute generation of p21+SEN cells mediate RTx-related skeletal deterioration and BMSC dysfunction, but targeted early clearance of p21+SEN cells can alleviate RTx-related chronic skeletal deterioration and promote fracture healing”. To test our central hypothesis, our aims are: (aim 1)To identify key mechanisms that are involved in RTx-related skeletal deterioration following early clearance of p21+SEN cells in young and aged mice, (aim 2): To assess bone architectural changes following cell specific clearance (using our novel Cre-LoxP mice, p21-LOX-ATTAC) of p21+Cd11b+SEN myeloid cells and (aim3): To assess if prior clearance of senescent cells pharmacologically or by genetic clearance of p21+SEN cells will promote fracture healing. The project will address questions related to basic biology of aging and role of p21 in skeletal cells and lay the groundwork to support the idea that an early intervention could prove effective to counter adverse changes from RTx, and to alleviate chronic skeletal deterioration and reduce the risk of potential fractures.

项目摘要/摘要 骨骼定义和相关骨折风险在接受的癌症存活中加剧 辐射处理（RTX），影响独立的生活和降低生活质量。细胞感应，之一 RTX诱导的DNA损伤后引起的主要途径的特征是促炎 感应相关的秘密表型（SASP，由趋化因子，细胞因子，生长因子，基质组成 降解酶等，主要受细胞周期蛋白依赖性激酶抑制剂（CDKI）P16INK4A和 P21CIP1。直到最近，人们了解到P16INK4A和P21CIP1在所有感觉细胞中共表达并调节 它们的功能互换。但是，该理论与p16ink4a的表达模式不匹配， P21CIP1后RTX或衰老。使用基因表达和RNA原位杂交研究，我们最近有 表明细胞在独特的骨髓细胞，成骨细胞和骨细胞的独特种群中表达p21或p16ink4a 独立于任何一个感应标记的表达。只有一小部分细胞表达p16Ink4a 和P21CIP1。此外，我们使用骨细胞的质量细胞仪具有引人入胜的初步数据， 允许我们可视化P16INK4A和P21CIP1表达细胞的这些独特的独特种群 SASP的共表达，表明这些CDKI的身体功能。有趣的是，在平行分析中 在辐射的骨骼中，我们确定了CD11b+ P21+髓样细胞群的升高，这已完成 通过表达几个SASP因子，从而使我们能够将这些P21+细胞表征为P21+ Senscent （P21+SEN）细胞。在最近的第二个发现中，使用带有转基因的转基因小鼠，可以使选择性 消除P16INK4A或P21CIP1表达细胞，消除P21-ATTAC中的P21+SEN细胞 [通过针对caspase的靶向激活凋亡]小鼠，但不能消除p16-ink-- ATTAC小鼠可以减轻年轻小鼠骨骼中与RTX相关的大多数不良事件。是否这样 清除p21+sen细胞的方法将有效减轻与RTX相关的骨骼恶化，而旧小鼠中的骨骼恶化 具有预先存在的感觉细胞的高燃烧尚待观察。基于我们引人入胜的初步 数据，我们将测试我们的中心假设：“急性生成P21+SEN细胞介导与RTX相关的骨骼 恶化和BMSC功能障碍，但针对P21+SEN细胞的靶向早期清除可以减轻与RTX相关的相关性 慢性骨骼恶化并促进断裂愈合。为了检验我们的中心假设，我们的目标是：（目标 1）确定与RTX相关的骨骼定义涉及的关键机制。 p21+年轻小鼠和年龄小鼠的SEN细胞（AIM 2）：评估细胞特异性的骨结构变化 p21+cd11b+sen髓样细胞和（aiM3）的清除（使用我们的新型Cre-loxp小鼠，p21-lox-attac）和（aiM3）： 评估先前清除Senscent细胞药物或通过p21+SEN细胞的遗传清除率是否会 促进断裂愈合。该项目将解决与衰老基本生物学和p21的作用有关的问题 骨骼细胞并奠定基础，以支持早期干预可以证明有效反击的想法 RTX的不良变化，以减轻慢性骨骼定义并降低潜在的风险 断裂。