Intrinsic and extrinsic mechanisms regulating asymmetric cell division in C. elegans

调节线虫不对称细胞分裂的内在和外在机制

• 批准号: RGPIN-2016-03979
• 负责人: Hawkins, Nancy
• 金额: $ 2.26万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=614760
• 关键词: Intrinsic; extrinsic; mechanisms; regulating; asymmetric

Asymmetric cell division, the process by which a mother cell divides to produce two daughter cells that adopt distinct cell fates, is a key mechanism that generates cellular diversity during development. Both the asymmetric localization of intracellular proteins and cell signaling contribute to this process. Despite numerous studies many outstanding questions remain. How does cell signaling polarize asymmetrically dividing cells? How does an organism integrate cell signaling to regulate the asymmetric localization of intracellular determinants. C. elegans is ideally suited address these questions since the majority of cells are generated by asymmetric cell division. Because the entire cell lineage is known, the timing, location and polarity of cell divisions can be analyzed at the resolution of single cells. My long-term goal is to elucidate the molecular and cellular mechanisms underlying asymmetric cell division in C. elegans. We have focused our analysis on the Wnt signalling pathway and HAM-1, a protein asymmetrically localized to the cell cortex in many dividing cells. In C. elegans, Wnt signaling regulates many asymmetric cell divisions. The Wnt pathway is a conserved cell-signaling pathway that is essential for development. In our previous NSERC funded research we showed that DSH-2, a key Wnt pathway component, regulates asymmetric neuroblast division during development and thus contributes to neuronal diversity. We undertook a highly successful genetic screen to identify genes that function with the Wnt/DSH-2 signaling pathway. One of the genes identified was hcf-1, a transcriptional co-activator. This was a novel finding since a role for hcf-1 in Wnt signalling has not been previously described in any experimental system. We proceeded to show that HCF-1 contributes to the asymmetric localization of the Wnt transcription factor POP-1/TCF. In this research proposal, we aim to determine the mechanism by which HCF-1 regulates POP-1 localization. Preliminary results indicates HCF-1 is likely affecting the acetylation of POP-1 and we will undertake experiments to test this hypothesis. We have cloned a second dsh-2 interacting gene and it encodes a novel protein. We will perform a combination of genetic, molecular and cell biological experiments to understand how this protein regulates Wnt dependent asymmetric cell division. We will also make use of whole genome sequencing to determine the molecular identity of additional mutations isolated in our genetic screen. Finally, we have shown that two other C. elegans Dishevelled homologs, DSH-1 and MIG-5, physically interact with HAM-1. This interaction provides a key link between cell signalling and the asymmetric localization of intracellular proteins. We propose experiments to investigate the role of Wnt signalling in the asymmetric localization of HAM-1.

不对称细胞分裂，即母细胞分裂产生两个具有不同细胞命运的子细胞的过程，是在发育过程中产生细胞多样性的关键机制。细胞内蛋白质的不对称定位和细胞信号传导都有助于这一过程。尽管进行了大量研究，但仍存在许多悬而未决的问题。细胞信号是如何阻止细胞不对称分裂的？生物体如何整合细胞信号以调节胞内决定簇的不对称定位。C.由于大多数细胞是通过不对称细胞分裂产生的，因此elegans非常适合解决这些问题。由于整个细胞谱系是已知的，因此可以在单个细胞的分辨率下分析细胞分裂的时间、位置和极性。 我的长期目标是阐明C.优美的我们的分析集中在Wnt信号通路和HAM-1上，HAM-1是一种在许多分裂细胞中不对称定位于细胞皮质的蛋白质。In C.在线虫中，Wnt信号调节许多不对称细胞分裂。Wnt信号通路是一种保守的细胞信号通路，对发育至关重要。在我们以前的NSERC资助的研究中，我们表明DSH-2，一个关键的Wnt通路成分，在发育过程中调节不对称的神经母细胞分裂，从而有助于神经元的多样性。我们进行了一个非常成功的遗传筛选，以确定与Wnt/DSH-2信号通路的功能基因。其中一个基因是hcf-1，一种转录辅激活因子。这是一个新的发现，因为hcf-1在Wnt信号传导中的作用以前没有在任何实验系统中描述过。我们进而表明HCF-1有助于Wnt转录因子POP-1/TCF的不对称定位。在这项研究中，我们的目标是确定HCF-1调节POP-1定位的机制。初步结果表明HCF-1可能影响POP-1的乙酰化，我们将进行实验来验证这一假设。我们已经克隆了第二个dsh-2相互作用基因，它编码一种新的蛋白质。我们将进行遗传，分子和细胞生物学实验的组合，以了解这种蛋白质如何调节Wnt依赖的不对称细胞分裂。我们还将利用全基因组测序来确定在我们的遗传筛选中分离的其他突变的分子身份。最后，我们证明了另外两个C。线虫Dishevelled同源物DSH-1和DSH-5与HAM-1物理相互作用。这种相互作用提供了细胞信号传导和细胞内蛋白质的不对称定位之间的关键联系。我们提出的实验，调查的作用Wnt信号在HAM-1的不对称定位。