Lung developmental defects caused by type I collagen mutations in mouse models of osteogenesis imperfecta

骨骼发育不良的患者，包括成骨不全(OI)，通常患有先天性呼吸 这些问题限制了治疗机会，增加了围产期和儿童早期死亡率。油井 是由COL1A1和COL1A2基因的显性突变或相关基因的功能丧失引起的 COL1加工(例如，CRTAP，编码胶原蛋白翻译后修饰所必需的蛋白质)和 折叠)。目前的概念是OI的呼吸异常继发于骨骼缺陷， 如胸壁畸形和脊柱曲度偏差(脊柱后凸)，这不允许 肺的适当扩张和充气导致限制性疾病。我们演示了Col1的生产 在缺乏CrTAP基因的OI小鼠模型的肺成纤维细胞中，CRTAPKO基因表达失调。这些老鼠也 表现为肺泡形成缺陷、肺泡上皮细胞丢失和几种基因改变。 表达，包括减少的肌成纤维细胞标记物，通过空间分辨转录组学进行量化。在……里面 此外，CRTAPKO小鼠和其他两种COL1突变的OI小鼠模型(Col1a2G610C/和OIM/OIM) 在3个月龄时表现出呼吸力学的改变。基于这一证据，因为Col1是 在包括肺在内的大多数组织中表达，我们的中心假设是患者的呼吸缺陷 与OI和其他骨骼发育不良是由于固有的肺功能障碍，在未来可以治疗 和/或独立于骨骼脆性进行校正。具体目标是1)剖析 内源性肺缺陷与外源性骨骼缺陷对OI肺功能损害的比较；2)细胞解体 以及COL1缺陷导致肺发育异常和受损的分子机制 呼吸功能。为了验证我们的假设，我们组建了一个具有互补专业知识的团队， 有能力完成我们的目标。具体目的是：确定一部小说的呼吸表型 在肺中表达经典Col1a1 OI甘氨酸替代突变的敲除小鼠模型 并将其与全球表达该突变的小鼠的骨骼(Col1a1Flox/；Tbx4-Cre)进行比较(目标1)。至 识别肺泡形态发生受损的原因和导致肺泡改变的关键途径 CRTAPKO细胞培养和类有机物中间充质-上皮细胞的相互作用(目标2)。找出原因 小鼠肺泡形态发生及肺细胞形态和功能异常的体内研究 以100微米或更高的横向分辨率在5-7微米的肺切片上分析整个转录组 肺泡形成的关键阶段(目标3)。总之，目标1-3将提供机械性的见解并建立 胶原蛋白基质与OI肺固有缺陷细胞功能障碍的关系 更好地了解基质在肺发育的最后阶段中的作用。最终，这项工作将 为肺内更常见的胶原蛋白失调疾病提供新的见解，如纤维化和 支气管肺发育不良。

Patients with skeletal dysplasias, including osteogenesis imperfecta (OI), often suffer from congenital respiratory problems that have limited therapeutic opportunities, and increased perinatal and early childhood mortality. OI is caused by dominant mutations in COL1A1 and COL1A2 genes or by loss of function of genes involved in COL1 processing (e.g., CRTAP, encoding an essential protein for collagen post-translational modification and folding). The current concept is that the respiratory abnormalities in OI are secondary to the skeletal defects, such as thoracic wall deformities and deviations of the spine curvature (kyphoscoliosis), which do not allow proper expansion and inflation of the lungs leading to restrictive disease. We demonstrated that COL1 production is dysregulated in lung fibroblasts from a mouse model of OI lacking the Crtap gene (CrtapKO). These mice also exhibit defective lung alveolar formation, loss of alveolar epithelial cells, and several changes in genes expression, including decreased myofibroblast markers, as quantified by spatially resolved transcriptomics. In addition, CrtapKO mice and two others mouse models of OI with COL1 mutations (Col1a2G610C/+ and oim/oim) exhibit altered respiratory mechanics at 3 months of age. Based on this evidence and because COL1 is expressed in most tissues including the lung, our central hypothesis is that the respiratory defects in patients with OI and other skeletal dysplasias are due to intrinsic lung dysfunction that, in the future, could be treated and/or corrected independently from the skeletal fragility. The specific goals are 1) dissect the contribution of intrinsic lung defects versus extrinsic skeletal defects to impaired lung functions in OI; and 2) unravel cellular and molecular mechanisms triggered by COL1 defects leading to abnormal lung development and impaired respiratory function. To test our hypothesis, we assembled a team with complementary expertise that is uniquely positioned to accomplish our goals. The specific aims are: to determine the respiratory phenotype of a novel knock-in mouse model expressing a classical Col1a1 OI glycine substitution mutation in the lung but not in the skeleton (Col1a1Flox/+;Tbx4-Cre) and compare it to that of mice expressing this mutation globally (aim 1). To identify the cause of impaired alveolar morphogenesis and key pathways contributing to changes in alveolar mesenchymal-epithelial cell interactions in CrtapKO cell cultures and organoids (aim 2). To identify causes of impaired alveolar morphogenesis and abnormal patterning and function of lung cells in CrtapKO mice in vivo by analyzing the entire transcriptome in 5-7 µm lung sections with 100 µm or better lateral resolution during the critical stage of alveolar formation (aim 3). Together, aims 1-3 will provide mechanistic insights and establish the relationship between the collagen matrix and cellular dysfunction causing lung-intrinsic defects in OI leading to a better understanding of the role of the matrix in the last stage of lung development. Ultimately, this work will provide new insights into more common diseases of collagen dysregulation in the lung such as fibrosis and bronchopulmonary dysplasia.