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

基本信息

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
项目类别：
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

项目摘要

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.

项目概要/摘要接受治疗的老年癌症幸存者的骨骼恶化和相关骨折风险加剧放射治疗（RTx），影响独立生活，降低生活质量，其中之一。 RTx 诱导的 DNA 损伤后诱导的主要途径，其特点是促炎衰老相关分泌表型（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 和直到最近，人们才知道p16Ink4a和p21Cip1在所有衰老细胞中共表达并受到调节。然而，该理论与 p16Ink4a 和 p16Ink4a 的表达模式不匹配。最近，我们利用基因表达和 RNA 原位杂交研究 p21Cip1 后 RTx 或老化。研究表明，在独特的骨髓细胞、成骨细胞和骨细胞群体中，细胞表达 p21 或 p16Ink4a 与任一衰老标记物的表达无关，只有一小部分细胞同时表达 p16Ink4a。此外，我们使用骨细胞的质谱流式分析获得了令人信服的初步数据。使我们能够可视化这些独立独特的 p16Ink4a 和 p21Cip1 表达细胞群，而无需任何 SASP 的共表达，表明这些 CDK 的生理功能。在辐射骨骼中，我们发现 Cd11b+p21+ 骨髓细胞群水平升高，并伴随通过表达几种 SASP 因子，从而使我们能够将这些 p21+ 细胞表征为 p21+ 衰老细胞 (p21+SEN) 细胞在最近的一项开创性发现中，使用含有转基因的转基因小鼠来实现选择性。消除 p16Ink4a 或 p21Cip1 表达细胞，消除 p21-ATTAC 中的 p21+SEN 细胞 [通过靶向激活caspase实现细胞凋亡]小鼠，但不消除p16-INK-中的p16+SEN细胞 ATTAC 小鼠，可以减轻年轻小鼠骨骼中大多数与 RTx 相关的不良事件。清除 p21+SEN 细胞的方法将有助于减轻老年小鼠与 RTx 相关的骨质退化，这根据我们的初步研究，是否存在预先存在的高衰老细胞负担，还有待观察。数据，我们将测试我们的中心假设：“p21+SEN 细胞的急性产生介导 RTx 相关的骨骼恶化和 BMSC 功能障碍，但有针对性地早期清除 p21+SEN 细胞可以缓解 RTx 相关的情况慢性骨骼退化并促进骨折愈合”为了检验我们的中心假设，我们的目标是：（目标） 1) 确定早期清除 RTx 相关骨骼退化的关键机制年轻和老年小鼠的 p21+SEN 细胞（目标 2）：评估细胞特异性后的骨结构变化 p21+Cd11b+SEN 骨髓细胞的清除（使用我们的新型 Cre-LoxP 小鼠 p21-LOX-ATTAC）和（目标 3）：评估先前通过药理学或通过 p21+SEN 细胞的遗传清除来清除衰老细胞是否会该项目将解决与衰老的基本生物学和 p21 在骨折中的作用相关的问题。骨骼细胞，并为支持早期干预可以有效对抗这一观点奠定了基础 RTx 的不良变化，并长期缓解骨骼恶化并降低潜在的风险骨折。