Conditional mouse models with dominant negative Osteogenesis Imperfecta

这项R21应用的目标是将现有的中度和重度成骨小鼠模型 将由1型胶原突变引起的不完全性（OI）转化为中度和重度OI的条件性小鼠模型。 条件小鼠模型提供了几个优于现有品系的优点。第一，条件小鼠品系 可以由公共储存库维护和分发;现有的菌株在各个实验室，而不是在 因为它们的骨骼脆弱。其次，OI是一种多系统疾病，影响骨骼，心脏， 肺、肌腱、韧带和皮肤。当研究OI时，一个器官系统中的表型（例如，心脏或肺）是 被另一器官系统中的疾病相关问题混淆（例如，脊柱和肋骨）。条件性小鼠 其中Cre重组酶用于以组织特异性方式表达突变蛋白的模型最小化了 这混乱。目前，还没有1型胶原蛋白突变的条件性小鼠模型，甚至 尽管约85%的人类OI是由这种突变引起的。第三，通过将现有菌株转化为有条件的 菌株，用条件菌株获得的任何新数据都可以与先前公布的数据进行比较 因为研究的是相同的突变我们将修改现有的等位基因插入基因陷阱使用i- GONAD基因编辑技术应用基因陷阱和i-GONAD将使我们能够有效地转化4 将小鼠中现有的引起OI的等位基因（Aga 2、Jrt、Brtl和p.G610C）转化为条件性引起OI的等位基因。鼠标 具有新的条件等位基因的菌株可以由公共储存库分发。我们还将确定 诱导肥大软骨细胞中突变型1型胶原内源性表达的作用， 已经显示肥大软骨细胞转分化成成骨细胞和骨祖细胞。 因此，重要的是要知道，如果骨性能受到强烈影响的细胞表达突变型1 胶原蛋白来自肥大的软骨细胞，或者如果未受影响的骨形成细胞 来自其他祖细胞来源的突变肥大软骨细胞来源的细胞补偿或胜过突变肥大软骨细胞来源的细胞。 后裔后一种知识将有助于对使用细胞疗法感兴趣的研究人员， 用野生型替代/替换突变型成骨细胞和骨祖细胞。

The goal of this R21 application is to convert existing mouse models of moderate and severe Osteogenesis Imperfecta (OI) caused by type 1 collagen mutations to conditional mouse models of moderate and severe OI. Conditional mouse models offer several advantages over the existing strains. First, conditional mouse strains can be maintained and distributed by public repositories; existing strains are in individual labs, and not in repositories, because of their skeletal fragility. Second, OI is a multi-system disease that affects bone, heart, lung, tendon, ligament, and skin. When studying OI, the phenotype in one organ system (e.g., heart or lung) is confounded by disease-associated problems in another organ system (e.g., spine and ribs). Conditional mouse models in which Cre-recombinase is used to express the mutant protein in a tissue-specific manner minimizes this confounding. Currently, there are no conditional mouse models with type 1 collagen mutations, even though ~ 85% of human OI is caused by such mutations. Third, by converting existing strains to conditional strains, any new data obtained with the conditional strains can be compared to previously published data because the same mutation was studied. We will modify existing alleles by inserting a gene-trap using i- GONAD gene-editing technology. Applying gene-traps and i-GONAD will enable us to efficiently convert 4 existing OI-causing alleles (Aga2, Jrt, Brtl, and p.G610C) in mice to conditional OI-causing alleles. Mouse strains with the new conditional alleles can be distributed by public repositories. We will also determine the effect of inducing endogenous expression of mutant type 1 collagen in hypertrophic chondrocytes, since hypertrophic chondrocytes have been shown to transdifferentiate into osteoblasts and osteoprogenitors. Therefore, it is important to know if bone properties are strongly influenced by cells expressing mutant type 1 collagen that have descended from hypertrophic chondrocytes, or if unaffected bone forming cells descended from other progenitor sources compensate for, or outcompete, the mutant hypertrophic chondrocyte-derived descendants. This latter knowledge will aid investigators who are interested in using cell therapies to displace/replace mutant osteoblasts and osteoprogenitors with wild-type ones.