Adaptive modulation of physiological traits in response to environmental variability, particularly dietary fluctuations, is essential for organismal fitness. Such adaptability is governed by complex gene-diet interactions, yet the molecular circuits integrating microbe-derived metabolites with host metabolic and stress response pathways remain less explored. Here, we identify the conserved mechanistic target of rapamycin complex 2 (mTORC2) component, RICTOR, as a critical regulator of dietary plasticity in Caenorhabditis elegans , specifically in response to bacterially derived vitamin B12 (B12). Loss of rict-1 , the C. elegans ortholog of RICTOR, confers enhanced osmotic stress tolerance and longevity on B12-rich bacterial diets. These phenotypic adaptations require two B12-dependent enzymes: methionine synthase (METR-1), functioning in the folate-methionine cycle (Met-C), and methylmalonyl-CoA mutase (MMCM-1), a mitochondrial enzyme essential for propionate catabolism. The latter catalyzes the formation of succinyl-CoA, subsequently converted to succinate via the tricarboxylic acid (TCA) cycle. Elevated succinate levels were found to induce mitochondrial fragmentation, thereby activating mitophagy, an autophagic process indispensable for the increased stress resilience and longevity observed in the rict-1 mutants. Crucially, this Met-C-mitophagy axis is modulated by microbial inputs, with B12 and methionine acting as proximal dietary signals. Our findings delineate a mechanistic framework through which RICTOR restrains host sensitivity to microbial-derived metabolites, thus maintaining mitochondrial homeostasis and regulating lifespan. This work reveals a pivotal role for RICTOR in insulating host physiology from environmental nutrient-driven perturbations by modulating organellar quality control pathways.

GNAO1 encephalopathies are a group of neglected genetic disorders primarily occurring due to de-novo point mutations in the Gαo protein-encoding gene in human GNAO1. This gene is reported to be highly conserved among Caenorhabditis elegans (C. elegans) and humans, with a sequence similarity of nearly 80%. Signaling pathways involved in various neurotransmitters, including GPCR pathways can be easily studied in the C. elegans model system. Therefore, using this model system to delineate downstream effectors and clinical targets to Gαo can be highly advantageous. Mutations that cause GNAO1 encephalopathy can be easily replicated in transgenic C. elegans and validated by rescuing phenotypic defects, primarily locomotion and egg-laying defects in worms. Although there are recent technical advancements in understanding the interacting proteins, there are unclear and uncertain hypotheses that explain the effect of Gαo mutations in humans. Coming to the clinical aspect of this disorder, there are no available approved diagnostic procedures to detect GNAO1 encephalopathy in the early stages of life. The present diagnostic procedures reiterate symptoms and overlap with other neurological symptoms that record neglected data of cases. Therefore, here we provide an overview of past research and a perspective of future work, with the primary objective of focusing on GNAO1 encephalopathy.