SOX9 Expression Identifies A Novel Alveolar Stem Cell Population

摘要 虽然长期以来人们都知道肺在成年期会进行广泛的再生，但特定的干细胞 参与这一过程的细胞现在才被发现。最近的研究表明， 肺泡II型细胞是已知的肺泡干细胞群，其优先被激活以增殖 不同形式的伤害。我们的初步数据表明我们已经发现了一种新的干细胞 位于成年小鼠肺周围的细胞群。这些细胞构成II型细胞的亚群， 表达SOX 9，这是一种存在于肺发育中的转录因子，但其表达先前已被发现。 被认为会在成年后消退。我们的初步数据显示，Sox 9-谱系标记的细胞扩增，产生 部分左叶肺切除术后，新的肺泡结构优先出现在肺叶周围 对小鼠此外，Sox 9+和Sox 9阴性细胞都在三维空间中上调和重新表达SOX 9。 类器官培养物，进一步表明SOX 9的功能是促进肺泡细胞中的“干性”。鉴于这些 研究发现，我们假设Sox 9+细胞是初级肺泡干细胞，它们优先增殖， 为了重建体内平衡和肺切除术后的肺实质，它们是必要的， S 0X 9增强肺泡细胞的再生和分化潜力。我们将解决 这些问题使用谱系追踪，细胞类型特异性消融，离体测定和RNA- 测序方法。目的1将阐述Sox 9+细胞对体内平衡和细胞增殖的贡献。 肺切除术后的代偿性肺生长。目的2将确定Sox 9+细胞是否是必需的 用于维持肺泡内环境稳定和损伤修复。目标3将解决SOX 9表达是否可以 显著影响肺泡II型细胞的干细胞性。总的来说，回答这些问题将有助于 确定Sox 9+细胞和/或Sox 9蛋白是否是有助于加速肺转移的可行治疗靶点。 急性损伤后的修复。 !

ABSTRACT While the lung has long been known to undergo extensive regeneration during adulthood, the particular stem cells involved in this process are only now being discovered. Recent studies have indicated that a subset of alveolar Type II cells, a known stem cell population of the alveoli, are preferentially activated to proliferate following different forms of injuries. Our preliminary data indicate that we have identified a novel stem cell population located in the periphery of the adult mouse lung. These cells constitute a subset of Type II cells and express SOX9, a transcription factor present in lung development but one whose expression had been previously thought to subside by adulthood. Our preliminary data show that Sox9-lineage labeled cells expand, generating new alveolar structures preferentially in the periphery of the lung lobes following partial left lobe pneumonectomy in mice. Moreover, both Sox9+ and Sox9 negative cells upregulate and re-express SOX9 in 3-dimensional organoid cultures, further suggesting that SOX9 functions to promote “stemness” in alveolar cells. Given these findings, we hypothesize that Sox9+ cells are the primary alveolar stem cell, that they preferentially proliferate to repopulate the homeostatic and post-pneumonectomy lung parenchyma, that they are necessary for these processes, and that SOX9 enhances regenerative and differentiation potential of alveolar cells. We will address these questions using a combination of lineage tracing, cell-type specific ablation, ex vivo assays, and RNA- Sequencing approaches. Aim 1 will address the contribution of Sox9+ cells to both homeostasis and compensatory lung growth following pneumonectomy. Aim 2 will determine whether Sox9+ cells are essential for maintenance of alveolar homeostasis and injury repair. Aim 3 will address whether SOX9 expression can substantially influence the stemness of alveolar Type II cells. Collectively, answering these questions will help determine whether Sox9+ cells and/or SOX9 protein are viable therapeutic targets that will help accelerate lung repair following acute injury. !