Higher-order epistasis shapes natural variation in germ stem cell niche activity

• Published in: Nature communications 2023-05, Vol.14 (1), p.2824-2824, Article 2824
• Main Authors: Fausett, Sarah R., Sandjak, Asma, Billard, Bénédicte, Braendle, Christian
• Format: Article
• Language: English
• Subjects: 14; 14/19; 14/32; 14/34; 38; 42; 45; 631/136/2139; 631/136/2434; 631/181/2806; 631/208/182; Animals; Caenorhabditis elegans - genetics; Caenorhabditis elegans - metabolism; Caenorhabditis elegans Proteins - metabolism; Cell fate; Cell proliferation; Chromosome 2; Chromosome Mapping; Chromosomes; Development Biology; Epistasis; Epistasis, Genetic; Gene deletion; Gene mapping; Genetic modification; Genetics; Genome editing; Germ Cells - metabolism; Humanities and Social Sciences; Life Sciences; multidisciplinary; Natural populations; Quantitative genetics; Science; Science (multidisciplinary); Stem Cell Niche; Stem cells
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-38527-0

To study how natural allelic variation explains quantitative developmental system variation, we characterized natural differences in germ stem cell niche activity, measured as progenitor zone (PZ) size, between two Caenorhabditis elegans isolates. Linkage mapping yielded candidate loci on chromosomes II and V, and we found that the isolate with a smaller PZ size harbours a 148 bp promoter deletion in the Notch ligand, lag-2/Delta , a central signal promoting germ stem cell fate. As predicted, introducing this deletion into the isolate with a large PZ resulted in a smaller PZ size. Unexpectedly, restoring the deleted ancestral sequence in the isolate with a smaller PZ did not increase—but instead further reduced—PZ size. These seemingly contradictory phenotypic effects are explained by epistatic interactions between the lag-2/Delta promoter, the chromosome II locus, and additional background loci. These results provide first insights into the quantitative genetic architecture regulating an animal stem cell system. Stem cell niches regulate proliferation of stem cells, but variation in this control across natural populations has not been explored. Here they combine quantitative genetics and gene editing to show that natural variation in C. elegans germ stem cell niche activity is shaped by complex gene-gene interactions.