Genes, cells, and pathways that regulate urochordate allogeneic stem cell competition and their mammalian homologues

 描述（由申请人提供）：异基因造血细胞移植（HCT）用于高危白血病和骨髓衰竭患者。在HCT中，完整的供体造血对于持续植入和预防复发至关重要。在移植后环境中，克隆性白血病前体可以重新出现。在人类AML中，克隆性白血病前期进展发生在造血干细胞[HSC]阶段，并且每个可遗传的变化增加了克隆与正常HSC的竞争能力。我们测试了哺乳动物生殖系干细胞竞争，老化中的HSC竞争，以及在人类白血病中竞争性HSC的进展，这是基于我们早期对殖民脊索动物Botryllus schlosseri中生殖系和索马龛的干细胞竞争的研究。B。Schlosseri是一种尾索动物模式生物，其表现出天然干细胞介导的嵌合性，并且与人和小鼠共享干细胞相关的基因组和途径。当两个基因不同的菌落相遇时，它们要么使体外血管扩张，形成具有共同脉管系统的嵌合体，要么相互排斥。在一些嵌合体中，嵌合伴侣之一经历部分或完全重吸收。嵌合体中一方的循环生殖和/或体干细胞可以与另一方的生殖系和/或索马竞争并取代其。干细胞植入B。schlosseri在四个不同层面上受到监管：1）。融合或排斥; 2）.如果发生融合，失去伴侣的身体被再吸收; 3）。循环体干细胞与种子芽之间的竞争，用于无性全身发育;和4）。生殖系干细胞之间的干细胞竞争，决定了下一代的基因型。我们发现了控制融合/排斥的基因（BHF），并发现其他水平也是可遗传的。因此，遗传上不同的品系具有体干细胞，在嵌合体中，体干细胞在它们被再吸收的脆弱性方面不同，经历竞争以“赢得”或“失去”分化的组织[类似于再生]，并且赢得或失去分化的组织[类似于再生]。 失去生殖系生态位。干细胞竞争的每一个层次都具有生物学和医学意义：再吸收是干细胞损失（无法发芽）的模型;体细胞竞争与干细胞移植的可移植性有关，而种系干细胞竞争决定了哪些基因型是遗传的（生育力）。为了发现调节干细胞功能和移植潜力的基因和关键途径，我们建立了遗传上不同的B。对具有不同水平植入潜力（在嵌合体中不被吸收和/或在干细胞竞争中获胜的能力）的schlosseri菌株进行了测定，对其组织特异性RNA进行了测序，并分析了其基因表达谱。我们得到了一系列最有可能改变干细胞竞争潜力的候选基因和途径。我们将使用基因敲除技术来评估参与器官发生和性腺发育的体内迁移干细胞中不同基因的功能。最终，我们将测试这些途径是否调节异基因移植中的HSC竞争。

 DESCRIPTION (provided by applicant): Allogeneic hematopoietic cell transplantation (HCT) is used for patients with high-risk leukemias and bone marrow failure. In HCT, complete donor hematopoiesis is essential for sustained engraftment and prevention of relapse. In the post-transplant setting, clonal preleukemic precursors can re-emerge. In human AML, clonal preleukemic progression occurs in the hematopoietic stem cell [HSC] stage, and each heritable change increases the competitive competence of the clone vs normal HSC. We tested for mammalian germline stem cell competitions, for HSC competitions in aging, and in the progression of competitive HSC in human leukemias based on our early studies of stem cell competitions for germline and soma niches in the colonial chordate Botryllus schlosseri. B. schlosseri is an urochordate model organism that exhibits natural stem-cell mediated chimerism, and shares stem-cell associated gene sets and pathways with human and mouse. When two genetically distinct colonies meet, they either anastomose extracorporeal blood vessels to form a chimera with a common vasculature, or reject one another. In some chimeras, one of the chimeric partners undergoes partial or complete reabsorption. Circulating germ and/or somatic stem cells of one partner in a chimera can compete with and replace the germ line and/or soma of the other partner. Stem cell engraftment in B. schlosseri is regulated on four different levels: 1). fusion or rejection; 2). if fusion occurs, the body of the losing partner is resorbed; 3). competition between circulating somatic stem cells to seed buds for asexual whole body development; and 4). stem cell competition among germ line stem cells, which determines the genotype of the next generation. We discovered the gene (BHF) that controls fusion/rejection, and found that the other levels are also heritable. Thus, genetically distinct strains have somatic stem cells that, in a chimera, vary in their vulnerability to be resorbed, undergo competitions to "win" or "lose" differentiated tissue [akin to regeneration], and to win or lose germline niches. Each level of stem cell competition has biological and medical implications: resorption is a model for stem cell loss (failure to bud); somatic competitions relat to stem cell transplant engraftability, and germline stem cell competition determines which genotypes are inherited (fertility). To discover genes and key pathways that regulate stem cell functionality and engraftment potential, we established genetically distinct B. schlosseri strains with different levels of engraftment potential (the ability to not be resorbed in a chimera and/or o win in stem cell competition), sequenced their tissue specific RNAs, and analyzed their gene expression profiles. We arrived at a list of candidate genes and pathways that most likely alter stem cell competitive potential. We will use gene knockdown technology to assess the function of different genes in migrating stem cells in vivo that participate in organogenesis and gonad development. Eventually we will test whether these pathways regulate HSC competitions in allogeneic transplants.