Role of Shh/Brachyury axis in the maintenance of the postnatal intervertebral disc

Shh/Brachyury 轴在产后椎间盘维持中的作用

• 批准号: 10433845
• 负责人: Chitra L Dahia
• 金额: $ 55.3万
• 依托单位: HOSPITAL FOR SPECIAL SURGERY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-17 至 2026-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10433845
• 关键词: Adult; Affect; Age; Age-Months; Aging; Agonist; Alleles; Appearance; Back Pain; Biological Assay; Brachyury protein; Cell Count; Cell Differentiation process; Cell Proliferation; Cells; Chondrocyte-like Cell; Chondrocytes; Chronic low back pain; Chronology; DISC components; Data; Development; Differentiation and Growth; Disease; Embryo; Epiphysial cartilage; Exhibits; Extracellular Matrix; Financial Hardship; Gene Expression; Genes; Genetic; Genetic Transcription; Goals; Growth; Health; Heterogeneity; Human; In Vitro; Individual; Injury; Intervertebral disc structure; Knock-out; Knowledge; Maintenance; Microscopic; Modeling; Molecular; Mus; Pain; Palliative Care; Pathologic; Pathology; Phenotype; Population; Population Heterogeneity; Process; Reporter; Research; Risk Factors; Role; SHH gene; Signal Transduction; Structure; Testing; Therapeutic; Therapeutic Uses; Time; Wages; Work; age related; aged; base; cartilaginous; conditional knockout; differential expression; effective therapy; emotional distress; in vivo; insight; intervertebral disk degeneration; knock-down; mouse model; neonatal mice; notochord; novel; nucleus pulposus; overexpression; postnatal; postnatal development; prevent; small molecule; smoothened signaling pathway; spine bone structure; therapeutic development; transcription factor; transcriptome; transcriptome sequencing; translational study

PROJECT SUMMARY/ ABSTRACT The goal of this proposal is to identify the role of critical developmental molecules in growth and maintenance of the postnatal intervertebral disc (IVD, or disc), and how the loss of these molecules with age results in pathological changes in the disc. The disc is a cartilaginous structure present between each vertebra. The disc has three components: notochord derived central nucleus pulposus (NP), surrounded by orthogonal layers of annulus fibrosus (AF), and endplate (EP) adjacent to the growth plate. With age or injury, the disc undergoes degenerative changes leading to chronic lower back pain (cLBP) affecting almost 80% of the adult US population. Much remains to be learned about the cellular and molecular basis of disc growth differentiation, and aging, that has limited development of effective therapies. We will use conditional genetic mouse models, lineage-tracing, and disc injury models to identify the function(s) of a crucial developmental regulator Brachyury (Bra) in the disc. Our central hypothesis is that Bra-expression by the NP cells is essential for disc growth and maintenance, and its loss during aging leads to the pathological changes in the disc. BRA is a T-box transcription factor and a notochordal marker. Previously, we showed that postnatal NP cells express Bra; but it’s expression decreases with age. We also found that sonic hedgehog (SHH), an important notochord signal secreted by NP cells, regulates postnatal disc growth and differentiation, and regulates Bra expression. While the total number of NP cells decreased with age, the Bra-expressing NP cells also decreased with age and were replaced by non-Bra-expressing "chondrocyte-like cells" (CLCs). The lineage relationship between CLCs and the Bra-expressing cells they replace is unknown, nor is it known how (or if) the loss of Bra expression leads to disc aging. Our preliminary data showed that all NP cells are lost in an aged mouse disc. We also showed that conditional targeting of Shh in adult mouse accelerates disc aging, along with the loss of Bra expression. We further showed that haploinsufficiency of Bra accelerates disc aging, providing the logical premise for this new project. Aim 1 tests the hypothesis that Bra is a primary transcriptional regulator downstream of SHH signaling, and regulates growth and maintenance of postnatal disc. Aim 2 will test the hypothesis that NP cells diverge into two molecularly heterogeneous populations, which differ with respect to Shh and Bra expression. Aim 3 will test the hypothesis that Bra controls the survival of NP cells, and prevents them from differentiating into "chondrocyte-like" cells. We expect that the findings from this study will provide insights into the role of developmental molecules in the maintenance of postnatal disc during growth and aging, and will identify avenues for targeting such molecules to reverse the aging process, aiding the development of therapeutics for the treatment of disc related disorders and LBP.

项目概要/摘要 该提案的目标是确定关键发育分子在生长和维持中的作用 出生后椎间盘（IVD，或椎间盘）的结构，以及这些分子随着年龄的增长而损失如何导致 椎间盘的病理变化 椎间盘是存在于每个椎骨之间的软骨结构。 具有三个组成部分：脊索衍生的中央髓核（NP），周围是正交的髓核层 邻近生长板的纤维环 (AF) 和终板 (EP) 随着年龄或损伤，椎间盘会发生变化。 导致慢性腰痛 (cLBP) 的退行性变化影响了近 80% 的美国成年人 关于椎间盘生长分化的细胞和分子基础，还有很多东西有待了解， 和衰老，这限制了有效疗法的发展，我们将使用条件遗传小鼠模型， 谱系追踪和椎间盘损伤模型，以确定关键发育调节因子 Brachyury 的功能 我们的中心假设是 NP 细胞的 Bra 表达对于椎间盘的生长和发育至关重要。 BRA 是一个 T 盒，它的维护和老化过程中的损失会导致椎间盘的病理变化。 之前，我们发现出生后的 NP 细胞表达 Bra；但是 我们还发现，声音刺猬（SHH）是一种重要的脊索信号，其表达量会随着年龄的增长而减少。 由 NP 细胞分泌，调节出生后椎间盘生长和分化，并调节 Bra 表达。 NP细胞总数随着年龄的增长而减少，表达Bra的NP细胞也随着年龄的增长而减少 被不表达 Bra 的“软骨细胞样细胞”(CLC) 取代 CLC 之间的谱系关系。 并且它们取代的表达 Bra 的细胞尚不清楚，也不知道如何（或是否）失去 Bra 表达 我们的初步数据表明，老化的小鼠椎间盘中所有的 NP 细胞都会丢失。 研究表明，在成年小鼠中条件性地靶向 Shh 会加速椎间盘老化，同时导致 Bra 的丧失 我们进一步表明，Bra 的单倍体不足会加速椎间盘老化，从而提供了逻辑。 这个新项目的前提是测试 Bra 是主要转录调节因子的假设。 SHH 信号传导的下游，并调节出生后椎间盘的生长和维护。目标 2 将测试 假设 NP 细胞分化成两个分子异质群体，这两个群体的不同之处在于 Shh 和 Bra 表达将检验 Bra 控制 NP 细胞存活并阻止其存活的假设。 我们希望这项研究的结果能够提供帮助。 深入了解发育分子在生长和衰老过程中维持产后椎间盘的作用， 并将确定针对此类分子逆转衰老过程的途径，帮助开发 用于治疗椎间盘相关疾病和 LBP 的疗法。