Mitochondrial stress in GABAergic neurons non-cell autonomously regulates organismal health and aging.

Mitochondrial stress within the nervous system can trigger non-cell autonomous responses in peripheral tissues. However, the specific neurons involved and their impact on organismal aging and health have remained incompletely understood. Here, we demonstrate that mitochondrial stress in γ-aminobutyric acid-producing (GABAergic) neurons in Caenorhabditis elegans ( C. elegans ) is sufficient to significantly alter organismal lifespan, stress tolerance, and reproductive capabilities. This mitochondrial stress also leads to significant changes in mitochondrial mass, energy production, and levels of reactive oxygen species (ROS). DAF-16/FoxO activity is enhanced by GABAergic neuronal mitochondrial stress and mediates the induction of these non-cell-autonomous effects. Moreover, our findings indicate that GABA signaling operates within the same pathway as mitochondrial stress in GABAergic neurons, resulting in non-cell-autonomous alterations in organismal stress tolerance and longevity. In summary, these data suggest the crucial role of GABAergic neurons in detecting mitochondrial stress and orchestrating non-cell-autonomous changes throughout the organism.

Comparative toxicities of BPA, BPS, BPF, and TMBPF in the nematode Caenorhabditis elegans and mammalian fibroblast cells.

Bisphenol A (BPA) is a chemical compound commonly used in the production of plastics for daily lives and industry. As BPA is well known for its adverse health effects, several alternative materials have been developed. This study comprehensively analyzed the toxicity of BPA and its three substitutes including bisphenol S (BPS), bisphenol F (BPF), and tetramethyl bisphenol F (TMBPF) on aging, healthspan, and mitochondria using an in vivo Caenorhabditis elegans (C. elegans) model animal and cultured mammalian fibroblast cells. C. elegans treated with 1 mM BPA exhibited abnormalities in the four tested parameters related to development and growth, including delayed development, decreased body growth, reduced reproduction, and abnormal tissue morphology. Exposure to the same concentration of each alternative including TMBPF, which has been proposed as a relatively safe BPA alternative, detrimentally affected at least three of these events. Moreover, all bisphenols (except BPS) remarkably shortened the organismal lifespan and increased age-related changes in neurons. Exposure to BPA and BPF resulted in mitochondrial abnormalities, such as reduced oxygen consumption and mitochondrial membrane potential. In contrast, the ATP levels were noticeably higher after treatment with all bisphenols. In mammalian fibroblast cells, exposure to increasing concentrations of all bisphenols (ranging from 50 µM to 500 µM) caused a severe decrease in cell viability in a dose-dependent manner. BPA increased ATP levels and decreased ROS but did not affect mitochondrial permeability transition pores (mPTP). Notably, TMBPF was the only bisphenol that caused a significant increase in mitochondrial ROS and mPTP opening. These results suggest that the potentially harmful physiological effects of BPA alternatives should be considered.

A novel role of the mitochondrial iron-sulfur cluster assembly protein ISCU-1/ISCU in longevity and stress response.

As an ancient cellular co-factor ubiquitously present in all domains of life, nearly all iron-sulfur ([Fe-S]) clusters are assembled in the mitochondrion. Although multiple mitochondrion-derived signalings are known to be key players in longevity regulation, whether the mitochondrial [Fe-S] cluster assembly machinery modulates lifespan is previously unknown. Here, we find that ISCU-1, the C. elegans ortholog of the evolutionarily conserved iron-sulfur cluster (ISC) assembly machinery central protein ISCU, regulates longevity and stress response. Specifically, ISCU-1 accelerates aging in the intestine. Moreover, we identify the Nrf2 transcription factor SKN-1 and a nuclear hormone receptor NHR-49 as the downstream factors of ISCU-1. Lastly, a mitochondrial outer membrane protein phosphatase PGAM-5 appears to link ISCU-1 to SKN-1 and NHR-49 in lifespan regulation. Together, we have identified a novel function of mitochondrial ISC assembly machinery in longevity modulation and stress response.