Mechano-niche in Lung Repair after Injury

损伤后肺修复中的机械利基

• 批准号: 10178490
• 负责人: YONG ZHOU
• 金额: $ 59.01万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-15 至 2025-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10178490
• 关键词: 3-Dimensional; AGTR2 gene; Ablation; Adverse effects; Alternative Splicing; Alveolar; Atomic Force Microscopy; Basement membrane; Biomechanics; Cell Lineage; Cells; Couples; Cues; Cytoplasmic Tail; Data; Ectopic Expression; Epithelial; Extracellular Matrix; Fibroblasts; Fluorescent in Situ Hybridization; Functional disorder; Genetic; Goals; Homeostasis; Human; Hydrogels; Impairment; Injury; Instruction; Integrin alpha6; Integrins; Intervention; Label; Lung; Lung diseases; Mechanics; Mediating; Mesenchymal; Mesenchyme; Microscopy; Molecular; Mus; Natural regeneration; Organoids; Pathologic; Platelet-Derived Growth Factor alpha Receptor; Property; Protein Isoforms; Pulmonary Fibrosis; RNA; RNA Splicing; Structure; Supporting Cell; Testing; Therapeutic; Tissues; Transcript; Variant; Work; differential expression; epithelial stem cell; ethylene glycol; idiopathic pulmonary fibrosis; injury and repair; lung injury; lung repair; mRNA Precursor; novel therapeutic intervention; prevent; progenitor; pulmonary function; repaired; self-renewal; stem; stem cell niche; stem cell self renewal; stem cells

Normal structure and function of the lung is maintained in homeostasis and repaired/regenerated following diverse injuries by regionally defined stem/progenitor cells. Stem cells reside in unique tissue microenvironments, known as the stem cell “niche”, which constitutes stem cell progeny, other niche-support cells including mesenchymal cells (MCs), and the surrounding extracellular matrix (ECM). The stem cell niche provides instructive cues for stem cell self-renewal and differentiation. Fibrotic lungs undergo substantial changes in the tissue biomechanical properties, manifested by stiffening of the ECM. Cells residing in the stem cell niche sense and respond to alterations in the stiffness of the microenvironment, highlighting matrix stiffness as an important mechanical component of the stem cell niche. In preliminary studies, we have characterized the stiffness of alveolar type 2 epithelial stem cell (AT2) niche associated with Pdgfrα+ lung MCs. Alveolar organoid culture in newly developed, stiffness-tunable 3D hydrogels demonstrated that matrix stiffness constitutes an AT2 niche. We recently identified that α6-integrin is a mechanosensitive integrin subunit; stiff matrix-induced α6 expression, primarily an α6 isoform with a shorter cytoplasmic domain (α6S), mediates lung fibroblast invasion into the basement membrane. New preliminary data now show that in addition to α6 expression, matrix stiffness regulates alternative splicing of α6 pre-mRNA in Pdgfrα+ lung MCs, resulting in differential expression of a distinct α6 isoform with a longer cytoplasmic domain (α6L) under soft /homeostatic matrix conditions and a switch from α6L to α6S predominance under stiff/fibrotic matrix conditions. We found that α6L expression promotes lipogenic differentiation of lung MCs and confers the AT2- niche function, facilitating reinstatement of lung homeostasis. In contrast, α6S expression impairs the AT2- niche function and promotes fibrogenic/invasive differentiation of lung MCs, contributing to lung fibrosis. In this proposal, we hypothesize that matrix stiffness-dependent alternative splicing of α6-integrin regulates the repair of injured lungs by controlling alveolotrophic vs. fibrogenic differentiation of lung mesenchymal cells. Specific aims in the proposed study are: (1) determination of the mechanisms by which matrix stiffness regulates alternative splicing of α6-integrin; (2) determination of the mechanisms by which distinct α6-integrin cytoplasmic variants mediate alveolotrophic vs. fibrogenic differentiation of lung mesenchymal cells; and (3) testing the potential of targeting matrix stiffness-dependent alternative splicing of α6-integrin for the reversal of sustained pulmonary fibrosis in mice. Understanding the mechanisms by which lung epithelial stem cells interact with their niches in normal vs. pathological repair of the injured lung will provide novel therapeutic approaches to prevent, treat, and potentially reverse pulmonary fibrosis.

肺的正常结构和功能保持在稳态中，并修复/再生以下 区域定义的茎/祖细胞造成的损伤。干细胞驻留在独特的组织中 微环境，称为干细胞“利基”，构成干细胞后代 包括间充质细胞（MCS）和周围细胞外基质（ECM）在内的细胞。干细胞小众 为干细胞自我更新和分化提供了启发性的提示。纤维化肺发生 组织生物力学特性的变化，表现为ECM的僵硬。居住在茎中的细胞 细胞生态位感并响应微环境刚度的改变，突出了矩阵 刚度是干细胞生态位的重要机械组成部分。在初步研究中，我们有 表征了与PDGFRα+肺MCS相关的2型肺泡2型上皮干细胞（AT2）的刚度。 新开发的，刚度可触摸的3D水凝胶中的牙槽有机培养表明基质 刚度构成一个AT2利基。我们最近确定α6-紧密蛋白是一种机械敏感的整联蛋白 亚基；刚性基质诱导的α6表达，一级Aα6同工型，具有较短的细胞质结构域（α6S）， 介导肺成纤维细胞侵袭地下膜。新的初步数据现在表明 除α6表达外，矩阵刚度调节pDGFRα+肺MC中α6前MRNA的替代剪接， 导致在软中具有较长细胞质结构域（α6L）的不同α6同工型的差异表达 /稳态基质条件，从刚/纤维化基质下从α6L到α6S优势的转换 状况。我们发现α6L表达促进了肺MC的脂肪生成分化，并承认AT2- 利基功能，支持恢复肺稳态。相反，α6S表达会损害AT2- 利基功能并促进肺MC的纤维化/侵入性分化，导致肺纤维化。在这个 提案，我们假设矩阵刚度依赖性替代剪接α6-整合素可以调节修复 通过控制肺间充质细胞的肺泡和纤维分化，通过控制肺部受伤的肺。具体的 拟议的研究中的目的是：（1）确定基质刚度调节的机制 α6-整合素的替代剪接； （2）确定不同α6-整合蛋白的机制 胞质变体介导肺间充质细胞的肺泡和纤维造成分化。 （3） 测试靶向基质刚度依赖性的替代剪接的潜力，以逆转 小鼠持续的肺纤维化。了解肺上皮干细胞的机制 在正常与肺部病理修复中与壁ni的相互作用将提供新颖的疗法 预防，治疗和潜在反向肺纤维化的方法。