Polyploidy after tissue injury: a Drosophila model

后生动物组织在组织和功能上是多样的。这就需要不同的机制来 受伤时要修复这些组织。我们率先对果蝇的后肠(大肠)进行了研究，以揭示新的 不同组织损伤反应的调节。使用这个模型，我们确定了组织损伤反应， 通过增加损伤后存活的细胞的DNA含量(倍体)和大小来恢复组织质量。这一增长 在倍性中，有一个保守的细胞周期，有S期，但没有细胞分裂，称为内周期。我们的发现 在组织修复中的内周期和多倍体细胞之后，在多发性损伤中也有类似的发现 哺乳动物组织，包括肾脏、膀胱和角膜。此外，我们的工作揭示了专门的 多倍体细胞在后肠和邻近中肠(小肠)之间受损边界的调节。在… 在这个边界上，我们鉴定了“杂交”细胞的双重后肠和中肠基因的表达。杂交细胞变得 在受伤时发生多倍体，同时与邻近中肠的干细胞进行广泛的串扰。但是，如果 杂交区严重受损，多倍体受到抑制，相邻的中肠干细胞形成 增生性侵袭性肿瘤。现在在哺乳动物的器官边界上也发现了类似的杂交区， 尤其是在干细胞丰富、易患癌症的胃/食道交界处。 这项提议利用了我们的专业知识、新发现和遗传顺从的果蝇模型来 明确组织损伤后多倍体的调节和功能。我们所提议的工作的意义是显而易见的。 在损伤反应的保守中，在损伤中的内环的保守，以及在 我们研究的分子，即JAK/STAT信号、Dichaete/SoxB1和fizzy相关/CDH1。我们的研究是 创新是因为它们表明，组织可以通过精确控制多倍体基因组数量来再生， 激素信号和SOX转录协同控制伤害诱导的多倍体，并且 再生多倍体器官边界可以抑制肿瘤的发生。在Aim1中，我们将揭示受伤的严重程度 确定再生过程中多倍体的程度。为了回答这个问题，我们将确定量化 不同损伤强度下JAK/STAT信号的参数和识别协调的特定通路步骤 损伤程度与内轮数目有关。AIM2将确定内环发生的分子机制 损伤而不是有丝分裂。为了回答这个问题，我们将考察保守派成员迪查特是如何 SOX转录因子家族，与激素信号合作，促进从损伤诱导的有丝分裂转换 循环进入内循环。AIM3将决定损伤后多倍体杂交细胞的来源和功能。至 回答这个问题，我们将区分干细胞依赖和干细胞非依赖的模型 器官边界再生。此外，这一目标将揭示杂交区和多倍体在 抑制干细胞肿瘤的侵袭。这三个目标都利用了转录数据和我们独特的精确度 损伤/遗传学系统，以识别进化保守的组织修复反应中的新分子参与者。

Metazoan tissues are diverse in organization and function. This necessitates diverse mechanisms to repair these tissues upon injury. We pioneered study of the Drosophila hindgut (large intestine) to reveal new regulation of diverse tissue injury responses. Using this model, we identified a tissue injury response whereby tissue mass is restored by increasing the DNA content (ploidy) and size of cells that survive injury. This increase in ploidy involves a conserved cell cycle with S phases but no cell division, called the endocycle. Our discovery of endocycles and polyploid cells in tissue repair has been followed by similar discoveries in multiple injured mammalian tissues, including the kidney, bladder, and cornea. Additionally, our work revealed specialized polyploid cell regulation at the injured boundary between the hindgut and adjacent midgut (small intestine). At this boundary, we identified “hybrid” cells of dual hindgut and midgut gene expression. Hybrid cells become polyploid upon injury while engaging in extensive cross-talk with stem cells in the adjacent midgut. However, if the hybrid zone is severely injured, polyploidy is suppressed, and the adjacent midgut stem cells form hyperplastic invasive tumors. Similar hybrid zones have now been discovered at mammalian organ boundaries, notably at the stem cell-enriched, cancer-prone stomach/esophagus boundary. This proposal leverages our expertise, new findings, and the genetically amenable Drosophila model to identify regulation and function of polyploidy after tissue injury. The significance of our proposed work is evident in the conservation of the injury response, the conservation of endocycles in injury, and the conservation of the molecules we study, namely JAK/STAT signaling, Dichaete/SoxB1, and fizzy-related/cdh1. Our studies are innovative because they show that tissues can regenerate by accurately controlling polyploid genome number, that hormonal signaling and Sox transcription cooperate to control injury-induced polyploidy, and that a regenerating polyploid organ boundary can suppress tumorigenesis. In Aim1, we will uncover how injury severity determines the extent of polyploidy during regeneration. To answer this question, we will identify quantitative parameters of JAK/STAT signaling at different injury strengths and identify specific pathway steps that coordinate injury level with endocycle number. Aim2 will identify the molecular mechanism by which endocycles occur after injury instead of mitosis. To answer this question, we will examine how Dichaete, a member of the conserved Sox transcription factor family, cooperates with hormone signaling to promote a switch from injury-induced mitotic cycles to endocycles. Aim3 will determine the origin and function of polyploid hybrid cells following injury. To answer this question, we will distinguish between stem cell-dependent and stem cell-independent models of organ boundary regeneration. Additionally, this aim will reveal the role of the hybrid zone and polyploidy in repressing stem cell tumor invasion. All three aims capitalize on transcriptomic data and our unique precision injury/genetics system to identify novel molecular players in an evolutionarily conserved tissue repair response.