Dept. of Developmental Genetics, Philipps University Marburg, Karl-von-Frisch-Str. 8, 35043 Marburg, Germany.
Core Facility Confocal and Multiphoton Microscopy, Universität Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
Eur J Cell Biol. 2024 Mar;103(1):151375. doi: 10.1016/j.ejcb.2023.151375. Epub 2023 Nov 18.
In the Drosophila testis, a group of stromal cells termed hub provides multiple niche signals for the surrounding germline and somatic stem cells. Stem cells of both populations compete for physical retention in the niche, and clones unable to transduce any one niche signal are rapidly eliminated from the stem cell pool by differentiation. We have mapped the transcriptomes of isolated somatic cyst stem cells and differentiated cyst cells, and found that the stem cells but not their differentiated progeny exhibit the signature of an innate immune response including the NF-κB transcription factor Relish (Rel). Related signalling pathways had previously implicated in cell competition in larval epithelia, prompting the question of whether NF-κB signalling was, despite the clear differences between the two competition scenarios, also involved in stem cell competition in the testis. Here we show i) that in the testis Rel is dispensable for stemness, ii) that loss of Rel or the upstream receptor Toll suppresses loser elimination following a variety of different triggers used to induce loser fate, and iii) that clonal Rel activation is sufficient for the displacement of neutral or winner cells from the niche, even if these cells otherwise retain stem cell properties.
在果蝇的睾丸中，一群被称为枢纽的间质细胞为周围的生殖细胞和体干细胞提供多种生态位信号。这两种细胞群的干细胞为了在生态位中的物理保留而竞争，并且无法传递任何一种生态位信号的克隆会通过分化迅速从干细胞池中被淘汰。我们已经对分离的体腔干细胞和分化的体腔细胞进行了转录组分析，发现干细胞而不是其分化的后代表现出先天免疫反应的特征，包括 NF-κB 转录因子 Relish (Rel)。相关的信号通路先前已被发现在幼虫上皮细胞的细胞竞争中起作用，这促使人们提出这样一个问题，即尽管两种竞争情况之间存在明显差异，NF-κB 信号是否也参与了睾丸中的干细胞竞争。在这里，我们表明：i）在睾丸中，Rel 对于干细胞特性是可有可无的；ii）Rel 或上游受体 Toll 的缺失会抑制在使用多种不同触发因素诱导失败者命运时的失败者消除；iii）克隆的 Rel 激活足以将中性或胜利者细胞从生态位中置换出来，即使这些细胞在其他方面保留了干细胞特性。
