Conditional mouse models with dominant negative Osteogenesis Imperfecta

这个R21应用程序的目标是转换现有的中度和重度成骨小鼠模型 由1型胶原突变引起的不完美(OI)到中、重度OI的条件性小鼠模型。 与现有的品系相比，条件性小鼠模型有几个优点。首先，有条件的小鼠品系 可以由公共存储库维护和分发；现有的毒株在单独的实验室中，而不是在 仓库，因为它们的骨架很脆弱。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。在研究OI时，一个器官系统(例如，心脏或肺)的表型是 被另一个器官系统(如脊柱和肋骨)的疾病相关问题所困扰。条件鼠标 使用Cre重组酶以组织特异性方式表达突变蛋白的模型最大限度地减少了 这令人困惑。目前，还没有出现1型胶原突变的条件性小鼠模型，甚至 然而，大约85%的人类OI是由这种突变引起的。第三，通过将现有菌株转换为条件性 用条件菌株获得的任何新数据都可以与以前发表的数据进行比较。 因为同样的突变也被研究过。我们将通过插入使用I-I的基因陷阱来修改现有的等位基因 性腺基因编辑技术。应用基因陷阱和i-性腺将使我们能够有效地将4 小鼠中现有的引起OI的等位基因(Aga2、JRT、Brt1和p.G610C)转变为条件性OI的等位基因。小白鼠 带有新的条件等位基因的菌株可以通过公共资料库进行分发。我们还将确定 诱导肥大软骨细胞内源性突变型胶原表达的作用 肥大的软骨细胞被证明可以转分化为成骨细胞和成骨前体细胞。 因此，了解骨骼特性是否受到表达突变类型1的细胞的强烈影响是很重要的 从肥大的软骨细胞下降的胶原蛋白，或者如果未受影响的骨形成细胞下降 来自其他祖细胞来源的补偿或竞争，突变的肥大软骨细胞来源 子孙后代。后一种知识将有助于对使用细胞疗法感兴趣的研究人员 用野生型成骨细胞和成骨祖细胞取代突变的成骨细胞和成骨祖细胞。

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.