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Insulin-mechanistic target of rapamycin (mTOR) signaling drives anabolic growth during organismal development; its late-life dysregulation contributes to aging and limits lifespans. Age-related regulatory mechanisms and functional consequences of insulin-mTOR remain incompletely understood. Here, we identify LPD-3 as a megaprotein that orchestrates the tempo of insulin-mTOR signaling during C. elegans aging. We find that an agonist insulin, INS-7, is drastically overproduced from early life and shortens lifespan in lpd-3 mutants. LPD-3 forms a bridge-like tunnel megaprotein to facilitate non-vesicular cellular lipid trafficking. Lipidomic profiling reveals increased hexaceramide species in lpd-3 mutants, accompanied by up-regulation of hexaceramide biosynthetic enzymes, including HYL-1. Reducing the abundance of HYL-1, insulin receptor/DAF-2 or mTOR/LET-363, normalizes INS-7 levels and rescues the lifespan of lpd-3 mutants. LPD-3 antagonizes SINH-1, a key mTORC2 component, and decreases expression with age. We propose that LPD-3 acts as a megaprotein brake for organismal aging and that its age-dependent decline restricts lifespan through the sphingolipid-hexaceramide and insulin-mTOR pathways.

How an organism dies is a fundamental yet poorly understood question in biology. An organism can die of many causes, including stress-induced phenoptosis, also defined as organismic death that is regulated by its genome-encoded programs. The mechanism of stress-induced phenoptosis is still largely unknown. Here, we show that transient but severe freezing-thaw stress (FTS) in Caenorhabditis elegans induces rapid and robust phenoptosis that is regulated by G-protein coupled receptor (GPCR) signaling. RNAi screens identify the GPCR-encoding fshr-1 in mediating transcriptional responses to FTS. FSHR-1 increases ligand interaction upon FTS and activates a cyclic AMP-PKA cascade leading to a genetic program to promote organismic death under severe stress. FSHR-1/GPCR signaling up-regulates the bZIP-type transcription factor ZIP-10, linking FTS to expression of genes involved in lipid remodeling, proteostasis, and aging. A mathematical model suggests how genes may promote organismic death under severe stress conditions, potentially benefiting growth of the clonal population with individuals less stressed and more reproductively privileged. Our studies reveal the roles of FSHR-1/GPCR-mediated signaling in stress-induced gene expression and phenoptosis in C. elegans, providing empirical new insights into mechanisms of stress-induced phenoptosis with evolutionary implications.

Cells adapt to cold by increasing levels of unsaturated phospholipids and membrane fluidity through conserved homeostatic mechanisms. Here we report an exceptionally large and evolutionarily conserved protein LPD-3 in C. elegans that mediates lipid trafficking to confer cold resilience. We identify lpd-3 mutants in a mutagenesis screen for genetic suppressors of the lipid desaturase FAT-7. LPD-3 bridges the endoplasmic reticulum (ER) and plasma membranes (PM), forming a structurally predicted hydrophobic tunnel for lipid trafficking. lpd-3 mutants exhibit abnormal phospholipid distribution, diminished FAT-7 abundance, organismic vulnerability to cold, and are rescued by Lecithin comprising unsaturated phospholipids. Deficient lpd-3 homologues in Zebrafish and mammalian cells cause defects similar to those observed in C. elegans. As mutations in BLTP1, the human orthologue of lpd-3, cause Alkuraya-Kucinskas syndrome, LPD-3 family proteins may serve as evolutionarily conserved highway bridges critical for ER-associated non-vesicular lipid trafficking and resilience to cold stress in eukaryotic cells.

TMEM132D is a human gene identified with multiple risk alleles for panic disorders, anxiety and major depressive disorders. Defining a conserved family of transmembrane proteins, TMEM132D and its homologs are still of unknown molecular functions. By generating loss-of-function mutants of the sole TMEM132 ortholog in C. elegans, we identify abnormal morphologic phenotypes in the dopaminergic PDE neurons. Using a yeast two-hybrid screen, we find that NAP1 directly interacts with the cytoplasmic domain of human TMEM132D, and mutations in C. elegans tmem-132 that disrupt interaction with NAP1 cause similar morphologic defects in the PDE neurons. NAP1 is a component of the WAVE regulatory complex (WRC) that controls F-actin cytoskeletal dynamics. Decreasing activity of WRC rescues the PDE defects in tmem-132 mutants, whereas gain-of-function of TMEM132D in mammalian cells inhibits WRC, leading to decreased abundance of select WRC components, impaired actin nucleation and cell motility. We propose that metazoan TMEM132 family proteins play evolutionarily conserved roles in regulating NAP1 protein homologs to restrict inappropriate WRC activity, cytoskeletal and morphologic changes in the cell.

Objective: Adrenocortical responsiveness is critical for maintaining glucocorticoids production and homeostasis during stress. We sought to investigate adrenocortical responsiveness during hypoxia in mice and the mechanisms responsible for the regulation of adrenal responsiveness. Methods: (1) Adult male WT mice were randomly divided into four groups: normoxia, hypoxia (24h), hypoxia (72h), hypoxia (72h) + GYY4137(hydrogen sulfide (H2S) donor, 133mmol/kg/day); (2) WT mice were randomly divided into four groups: sham, adrenalectomy (ADX), sham+hypoxia, ADX+hypoxia; (3) Cse-/- mice were randomly divided into two groups: Cse-/-, Cse-/- +GYY4137. Results: The circulatory level of corticosteroid induced by ACTH stimulation was significantly reduced in the mice with hypoxia compared with control mice. The mortality rate induced by lipopolysaccharide (LPS) increased during hypoxia. Cystathionine-γ-lyase (CSE) expression was significantly reduced in adrenal glands during hypoxia. GYY4137 treatment significantly increased adrenal responsiveness and attenuated NLRP3 inflammasome activation in mice treated by hypoxia and Cse-/- mice. Furthermore, The sulfhydrated level of PSMA7 in adrenal gland was decreased in the mice with hypoxia and Cse-/- mice. PSMA7 was S-sulfhydrated at cysteine 70. Blockage of S-sulfhydration of PSMA7 increased NLRP3 expression in adrenocortical cells. Conclusion: Reduced H2S production mediated hypo-adrenocortical responsiveness and NLRP3 inflammasome activation via PAMA7 S-sulfhydration during hypoxia. [ABSTRACT FROM AUTHOR]

Sepsis-associated acute kidney injury (SA-AKI) results in significant morbidity and mortality, and ferroptosis may play a role in its pathogenesis. Our aim was to examine the effect of exogenous H2S (GYY4137) on ferroptosis and AKI in in vivo and in vitro models of sepsis and explore the possible mechanism involved. Sepsis was induced by cecal ligation and puncture (CLP) in male C57BL/6 mice, which were randomly divided into the sham, CLP, and CLP + GYY4137 group. The indicators of SA-AKI were most prominent at 24 h after CLP, and analysis of the protein expression of ferroptosis indicators showed that ferroptosis was also exacerbated at 24 h after CLP. Moreover, the level of the endogenous H2S synthase CSE (Cystathionine-γ-lyase) and endogenous H2S significantly decreased after CLP. Treatment with GYY4137 reversed or attenuated all these changes. In the in vitro experiments, LPS was used to simulate SA-AKI in mouse renal glomerular endothelial cells (MRGECs). Measurement of ferroptosis-related markers and products of mitochondrial oxidative stress showed that GYY4137 could attenuate ferroptosis and regulate mitochondrial oxidative stress. These findings imply that GYY4137 alleviates SA-AKI by inhibiting ferroptosis triggered by excessive mitochondrial oxidative stress. Thus, GYY4137 may be an effective drug for the clinical treatment of SA-AKI. [ABSTRACT FROM AUTHOR]

Understanding the in vivo transport process provides guidelines for designing ideal nanoparticles (NPs) with higher efficacy and fewer off-target effects. Many factors, such as particle size, morphology, surface potential, structural stability, and etc., may influence the delivering process of NPs due to the existence of various physiological barriers within the body. Herein, we summarise the distinct influences of NP physicochemical properties on the four consecutive in vivo transport steps: (1) navigating with bloodstream within blood vessels, (2) transport across vasculature walls into tumour tissues, (3) intratumoural transport through the interstitial space, and (4) cellular uptake & intracellular delivery by cancerous cells. We found that the philosophy behind the current consensus for NP design has certain similarities to the "Yin-Yang" theory in traditional Chinese culture. Almost all physicochemical properties, regardless of big or small sizes, long or short length, positive or negative zeta potentials, are double-edged swords. The balance of potential benefits and side effects, drug selectivity and accessibility should be fully considered when optimising particle design, similar to the "Yin-Yang harmony". This paper presents a comprehensive review of the advancements in NPs research, focusing on their distinct features in tumour targeting, drug delivery, and cell uptake. Additionally, it deliberates on future developmental trends and potential obstacles, thereby aiming to uncover the ways these characteristics influence the NPs' biological activity and provide theoretical guidance for the targeted delivery of NPs., Competing Interests: Conflicts of interest statement: None.