An egg-laying programme drains a worm's lifespan as liver tumours start from different cells
Unrestrained egg production drains fat and lifespan in a nematode, while metabolic disease and alcohol lead mouse liver tumours toward different founding cells and immune responses.
Science··Midday
Egg production continues without sperm
In the nematode Caenorhabditis elegans, loss of the nuclear hormone receptor NHR-49 activated oocytes too early and the animal continued laying unfertilised eggs even when no sperm was present. Yolk and stored fat fell quickly, while lifespan shortened sharply. NHR-49 also restrains germline proliferation through somatic cells when food runs out. Genomic analyses identified the Gαs subunit GSA-1 as a direct target gene, defining part of the route from nutrient sensing to reproductive behaviour.[1]
Fat returns when resource export is blocked
When yolk transfer into the oocytes was blocked, fat stores largely returned and lifespan was partly restored. That experiment shows that the harm cannot be explained by oocyte activation alone; exporting resources into reproductive cells contributes directly to the outcome. The findings come from one nematode species. Although PPARα and HNF4α are mammalian counterparts of NHR-49, this study did not test whether the same link between reproduction and longevity operates in mammals.[1]
The route to liver disease changes the founding cell
In mice, CTNNB1-mutant liver tumours in the metabolic-disease model began in periportal and midlobular cells reprogrammed toward a perivenous identity, with the immunosuppressive IDO1-kynurenine-AhR pathway active. In the ethanol-inclusive model, tumours arose from more than one cell of origin and remained responsive to anti-PD-1 treatment. Blocking AhR with a drug, or deleting beta-catenin only in liver cells, reduced tumour burden and restored treatment response in the metabolic model. Every result comes from mouse models; no patient data were reported.[2]
