Dioscin integrates regulation of monosaturated fatty acid metabolism to extend the life span through XBP-1/SBP-1 dependent manner

The Roles of White Adipose Tissue and Liver NADPH in Dietary Restriction-Induced Longevity

Dietary restriction (DR) protocols frequently employ intermittent fasting. Following a period of fasting, meal consumption increases lipogenic gene expression, including that of NADPH-generating enzymes that fuel lipogenesis in white adipose tissue (WAT) through the induction of transcriptional regulators SREBP-1c and CHREBP. SREBP-1c knockout mice, unlike controls, did not show an extended lifespan on the DR diet. WAT cytoplasmic NADPH is generated by both malic enzyme 1 (ME1) and the pentose phosphate pathway (PPP), while liver cytoplasmic NADPH is primarily synthesized by folate cycle enzymes provided one-carbon units through serine catabolism. During the daily fasting period of the DR diet, fatty acids are released from WAT and are transported to peripheral tissues, where they are used for beta-oxidation and for phospholipid and lipid droplet synthesis, where monounsaturated fatty acids (MUFAs) may activate Nrf1 and inhibit ferroptosis to promote longevity. Decreased WAT NADPH from PPP gene knockout stimulated the browning of WAT and protected from a high-fat diet, while high levels of NADPH-generating enzymes in WAT and macrophages are linked to obesity. But oscillations in WAT [NADPH]/[NADP+] from feeding and fasting cycles may play an important role in maintaining metabolic plasticity to drive longevity. Studies measuring the WAT malate/pyruvate as a proxy for the cytoplasmic [NADPH]/[NADP+], as well as studies using fluorescent biosensors expressed in the WAT of animal models to monitor the changes in cytoplasmic [NADPH]/[NADP+], are needed during ad libitum and DR diets to determine the changes that are associated with longevity.

Cynaroside extends lifespan and improves the neurondegeneration diseases via insulin/IGF-1 signaling pathway in Caenorhabditis elegans

The evolutionarily conserved insulin/IGF-1 signaling pathway plays a central role in aging and aging related diseases such as neurodegeneration diseases. Inhibition of insulin/IGF-1 signaling pathway has been proposed as an effective way to extend lifespan and delay neurodegeneration diseases in different organisms. Cynaroside (Cyn), a flavonoid contained in many medical plants and in vegetables, had been shown to exhibit pharmacological properties such as anti-inflammatory, anti-tumor, and anti-oxidant effects. The study demonstrated that lifespan extension and neurodegeneration diseases improving could be achieved by targeting evolutionarily conserved insulin/IGF-1 pathway through using pharmacological interventions. Via using this approach in tractable model Caenorhabditis elegans, we found that 10 μM Cynaroside significantly promoted the healthy lifespan in wild-type animals. Furthermore, via genetic screen, we showed that Cynaroside acted on IGF-1-R /DAF-2, which was followed by the activation of transcription factor DAF-16/FOXO to extend the healthy lifespan. Intriguingly, Cynaroside also improved neurodegeneration diseases such as Alzheimer's and polyglutamine disease by suppressing insulin/IGF-1 signaling pathway. Our work suggests that Cynaroside may be a promising candidate for the prevention and treatment of aging and neurodegeneration diseases.

Reducing the metabolic burden of rRNA synthesis promotes healthy longevity in Caenorhabditis elegans

Ribosome biogenesis is initiated by RNA polymerase I (Pol I)-mediated synthesis of pre-ribosomal RNA (pre-rRNA). Pol I activity was previously linked to longevity, but the underlying mechanisms were not studied beyond effects on nucleolar structure and protein translation. Here we use multi-omics and functional tests to show that curtailment of Pol I activity remodels the lipidome and preserves mitochondrial function to promote longevity in Caenorhabditis elegans. Reduced pre-rRNA synthesis improves energy homeostasis and metabolic plasticity also in human primary cells. Conversely, the enhancement of pre-rRNA synthesis boosts growth and neuromuscular performance of young nematodes at the cost of accelerated metabolic decline, mitochondrial stress and premature aging. Moreover, restriction of Pol I activity extends lifespan more potently than direct repression of protein synthesis, and confers geroprotection even when initiated late in life, showcasing this intervention as an effective longevity and metabolic health treatment not limited by aging.

Dioscin Activates Endoplasmic Reticulum Unfolded Protein Response for Defense Against Pathogenic Bacteria in Caenorhabditis elegans via IRE-1/XBP-1 Pathway

The unfolded protein response (UPR) is an evolutionarily conserved pathway that senses and responds to the accumulation of misfolded proteins in the endoplasmic reticulum (ER) lumen during bacterial infection. The IRE-1/XBP-1 pathway is a major branch of the UPRER that has been conserved from yeast to human. Dioscin, a steroidal saponin exhibits a broad spectrum of properties. However, whether dioscin influences the immune response and the underlying molecular mechanisms remain obscure. We find that dioscin increases resistance to Gram-negative pathogen Pseudomonas aeruginosa. Furthermore, dioscin also inhibits the growth of pathogenic bacteria. Meanwhile, dioscin enhances the resistance to pathogens by reducing bacterial burden in the intestine. Through genetic screening, we find that dioscin activates the UPRER to promote innate immunity via IRE-1/XBP-1 pathway. Intriguingly, dioscin requires the neural XBP-1 for immune response. Our findings suggest that dioscin may be a viable candidate for the treatment of infectious diseases.

Dioscin inhibiting EGFR-mediated Survivin expression promotes apoptosis in oral squamous cell carcinoma cells

Overexpression of survivin plays a crucial role in tumorigenesis and correlates with poor prognosis in human malignancies, including oral squamous cell carcinoma (OSCC). Thus, survivin has been proposed as an attractive target for new antitumor interventions. In the present study, we found that a natural compound, Dioscin, inhibited OSCC cells by reducing the survivin protein level and activating apoptotic signaling. Dioscin inhibits survivin expression by interrupting EGFR binding to the AT-rich sequences (ATRSs) at the survivin promoter, eventually promoting survivin-mediated cell apoptosis. The in vivo study showed that Dioscin suppressed the tumor development of SCC25 cells. Furthermore, the immunohistochemistry (IHC) results revealed that treated with Dioscin reduced the protein levels of EGFR and survivin in SCC25 xenograft tumors. Overall, our findings indicate that targeting the EGFR-survivin axis might be a promising OSCC treatment strategy.