Germline loss in C. elegans enhances longevity by disrupting adhesion between niche and stem cells

Ageing and fertility are intertwined. Germline loss extends the lifespan in various organisms, a phenomenon termed gonadal longevity. However, the longevity signal from the somatic gonad remains elusive. Here, we focused on the interaction between germline stem cells (GSCs) and their niche, the distal tip cells (DTCs), to identify the longevity signal from the somatic gonad in C. elegans. We found that removing the germline disrupts the cell adhesions between GSCs and DTCs, causing significant transcriptomic changes in DTCs through hmp-2/-catenin and the GATA transcription factors, elt-3 and pqm-1. Inhibiting elt-3 and pqm-1 in DTCs suppresses gonadal longevity. Moreover, we identified the TGF- ligand, tig-2, as the cytokine secrected by DTCs upon germline loss, which evokes downstream gonadal longevity signalling throughout the body. Our findings thus reveal the stromal source of the longevity signalling in response to germline removal, highlighting the stem cell niche as a critical signalling hub in ageing.