Spitzer Danielle C, Sun William Y, Rodríguez-Vargas Anthony, Hariharan Iswar K
Department of Molecular and Cell Biology, 515 Weill Hall, University of California, Berkeley, Berkeley CA 94720-3200.
bioRxiv. 2023 Aug 6:2023.08.04.552072. doi: 10.1101/2023.08.04.552072.
The interactions that cells in imaginal discs have with their neighbors are known to regulate their ability to survive. In a screen of genes encoding cell surface proteins for gene knockdowns that affect the size or shape of mutant clones, we found that clones of cells with reduced levels of () are fewer, smaller, and can be eliminated during development. In contrast, discs composed mostly of mutant tissue are overgrown. We find that mutant tissue has lower levels of the anti-apoptotic protein Diap1 and has increased levels of apoptosis which is consistent with the observed underrepresentation of mutant clones and the slow growth of mutant tissue. The eventual overgrowth of mutant tissue results not from accelerated growth, but from prolonged growth resulting from a failure to arrest growth at the appropriate final size. Ed has previously been shown to physically interact with multiple Hippo-pathway components and it has been proposed to promote Hippo pathway signaling, to exclude Yorkie (Yki) from the nucleus, and restrain the expression of Yki-target genes. We did not observe changes in Yki localization in mutant tissue and found decreased levels of expression of several Yorkie-target genes, findings inconsistent with the proposed effect of Ed on Yki. We did, however, observe increased expression of several Yki-target genes in wild-type cells neighboring mutant cells, which may contribute to elimination of mutant clones. Thus, has two distinct functions: an anti-apoptotic function by maintaining Diap1 levels, and a function to arrest growth at the appropriate final size. Both of these are unlikely to be explained by a simple effect on the Hippo pathway.
已知成虫盘细胞与其相邻细胞之间的相互作用可调节其存活能力。在一项针对编码细胞表面蛋白的基因进行基因敲除的筛选中，这些基因敲除会影响突变克隆的大小或形状，我们发现（）水平降低的细胞克隆数量减少、体积变小，并且在发育过程中可能被消除。相比之下，主要由突变组织组成的成虫盘会过度生长。我们发现突变组织中抗凋亡蛋白Diap1的水平较低，凋亡水平升高，这与观察到的突变克隆数量减少以及突变组织生长缓慢一致。突变组织最终的过度生长并非源于生长加速，而是由于未能在适当的最终大小停止生长导致的生长延长。此前已证明Ed与多个Hippo信号通路成分存在物理相互作用，有人提出它可促进Hippo信号通路信号传导，将Yorkie（Yki）排除在细胞核外，并抑制Yki靶基因的表达。我们在突变组织中未观察到Yki定位的变化，并且发现几个Yorkie靶基因的表达水平降低，这些发现与Ed对Yki的推测作用不一致。然而，我们确实观察到在与突变细胞相邻的野生型细胞中，几个Yki靶基因的表达增加，这可能有助于消除突变克隆。因此，（）具有两种不同的功能：通过维持Diap1水平发挥抗凋亡功能，以及在适当的最终大小停止生长的功能。这两种功能都不太可能通过对Hippo信号通路的简单作用来解释。
