Heat stress promotes GTBP-1 association with perinuclear P-bodies in the C. elegans germline.

Stress granules (SGs) are dynamic ribonucleoprotein condensates that enable cells to adapt to environmental stress, yet their functions and regulation in the germline remain incompletely understood. Here, we characterize GTBP-1, the Caenorhabditis elegans homolog of human G3BP1, and investigate its role in heat stress responses and reproductive homeostasis. gtbp-1 mutants exhibit temperature-dependent reproductive phenotypes. Under normal growth conditions, GTBP-1 is diffusely distributed in the cytoplasm, whereas heat stress induces the formation of prominent GTBP-1 granules in the germline. Domain analysis revealed that the NTF2 domain is required for heat stress-induced GTBP-1 enrichment in granules, while the IDR, RRM, and RGG domains contribute to GTBP-1 granule dynamics. Among the known germ granule compartments, GTBP-1 granules showed the strongest association with P-bodies, and disruption of P-body components markedly reduces GTBP-1 enrichment. RNAi-based candidate screening identified PQN-59, LAF-1, and SMO-1 as regulators of GTBP-1 enrichment, while a forward genetic screen revealed that loss of the mTOR effector RSKS-1 suppresses the fertility defect of gtbp-1 mutants and alters heat stress-induced GTBP-1 enrichment. Together, these findings identify a role for GTBP-1 in temperature-dependent reproductive homeostasis and reveal an association between heat stress-induced GTBP-1 granules and P-bodies in C. elegans.