Somatic mutations are major genetic contributors to cancers and many other age-related diseases. Many disease-causing somatic mutations can initiate clonal growth prior to the appearance of any disease symptoms, yet experimental models that can be used to examine clonal abnormalities are limited. We describe a mosaic analysis system with Cre or Tomato (MASCOT) for tracking mutant cells and demonstrate its utility for modeling clonal hematopoiesis. MASCOT can be induced to constitutively express either Cre-GFP or Tomato for lineage tracing of a mutant and a reference group of cells simultaneously. We conducted mosaic analysis to assess functions of the Id3 and/or Tet2 gene in hematopoietic cell development and clonal hematopoiesis. Using Tomato-positive cells as a reference population, we demonstrated the high sensitivity of this system for detecting cell-intrinsic phenotypes during short-term or long-term tracking of hematopoietic cells. Long-term tracking of Tet2 mutant or Tet2/Id3 double-mutant cells in our MASCOT model revealed a dynamic shift from myeloid expansion to lymphoid expansion and subsequent development of lymphoma. This work demonstrates the utility of the MASCOT method in mosaic analysis of single or combined mutations, making the system suitable for modeling somatic mutations identified in humans.

体细胞突变是癌症和许多其他与年龄有关的疾病的主要遗传因素。许多引起疾病的体细胞突变可以在出现任何疾病症状之前启动克隆生长，但是可用于检查克隆异常的实验模型是有限的。我们描述了具有Cre或Tomato（MASCOT）的镶嵌分析系统，用于跟踪突变细胞，并证明其可用于建模克隆性造血。可以诱导MASCOT组成性表达Cre-GFP或Tomato，以同时追踪突变体和参考细胞组。我们进行了镶嵌分析以评估Id3和/或Tet2的功能基因在造血细胞发育和克隆性造血中的作用。使用番茄阳性细胞作为参考群体，我们证明了该系统在短期或长期追踪造血细胞过程中检测细胞内在表型的高度敏感性。在我们的MASCOT模型中对Tet2突变体或Tet2 / Id3双突变细胞的长期跟踪揭示了从髓样扩展到淋巴样扩展的动态转变，以及随后的淋巴瘤发展。这项工作证明了MASCOT方法在单个或组合突变的镶嵌分析中的实用性，使该系统适用于对人类识别出的体细胞突变进行建模。