The Probiotic Strain Lactobacillus acidophilus CL1285 Reduces Fat Deposition and Oxidative Stress and Increases Lifespan in Caenorhabditis elegans.

Caenorhabditis elegans was recently shown to be a powerful model for studying and identifying probiotics with specific functions. Lactobacillus acidophilus CL1285, Lacticaseibacillus casei LBC80R, and Lacticaseibacillus rhamnosus CLR2, which are three bacteria that were marketed by Bio-K+, were evaluated using the nematode C. elegans to study fat accumulation, lifespan, and resistance to oxidative stress. Although the general effects of probiotics in terms of protection against oxidative stress were highlighted, the CL1285 strain had an interesting and specific feature, namely its ability to prevent fat accumulation in nematodes; this effect was verified by both the Oil Red and Nile Red methods. This observed phenotype requires daf-16 and is affected by glucose levels. In addition, in a daf-16- and glucose-dependent manner, CL1285 extended the lifespan of C. elegans; this effect was unique to CL1285 and not found in the other L. acidophilus subtypes in this study. Our findings indicate that L. acidophilus CL1285 impacts fat/glucose metabolism in C. elegans and provides a basis to further study this probiotic, which could have potential health benefits in humans and/or in mammals.

A digital image analysis approach to understand the microscopic and macroscopic phenomena in dissolved air flotation.

Dissolved air flotation (DAF) is an effective method for separating suspended oil and solid particles from wastewater by utilizing small air bubbles. This study aims to investigate the impact of key factors, such as saturating pressure and water flow rate, on the separation of fine oil droplets from a water stream. The macroscopic flow patterns within the cell were analyzed using particle image velocimetry (PIV), while Digital Image Analysis (DIA) was employed to study microscopic phenomena, including oil droplet rising velocity and oil-bubble contact mechanisms. Our findings propose a safe operating window (specifically, water flow rate and saturation pressure) for the effective separation of oil droplets without any oil escaping into the clean water stream. It was found that the oil droplet rising velocity increases with the saturation pressure up to 200 kPa. However, a further increase in the pressure of the air saturating chamber leads to a decrease in oil droplet rising velocity. Additionally, we identified a peak in rising velocity at an oil droplet size of approximately 200 µm. Below this threshold, the rising velocity increases with droplet size, while for droplet sizes exceeding 200 µm, the rising velocity decreases with size. This behavior can be explained by the conflicting effects of droplet size increment according to the Stokes law for the rising velocity of oil droplets. As the droplet size increases, the average density of the bubbles/droplet aggregate rises, reducing the ∆ρ in the Stokes law and subsequently lowering the aggregate rising rate. However, as per the Stokes law, the oil droplet rising velocity increases proportionally to the square of its size.

Jujubae Fructus extract prolongs lifespan and improves stress tolerance in Caenorhabditis elegans dependent on DAF-16/SOD-3.

Jujubae Fructus, the fruit of Ziziphus jujuba Mill has been used as one of the medicine food homology species for thousands of years in China. Studies have shown that the active ingredients of Jujubae Fructus have a variety of biological effects, but its role in the aging process still lacks knowledge. Here, we investigated the effect of Jujubae Fructus extract (JE) on Caenorhabditis elegans lifespan and its potential mechanism. The lifespan of C. elegans treated with JE was signifificantly increased in a dose-dependent manner. In addition, JE treatment prolonged the reproductive period and increased normal activity during aging in C. elegans. Similarly, JE supplementation also enhanced the resistance to heat and oxidative stress in C. elegans. Furthermore, the mutant worms' lifespan assays demonstrated that JE requires daf-16 to prolong lifespan. DAF-16::GFP analysis of TJ356 showed that JE treatment translocates DAF-16::GFP to nucleus in transgenic worms. By analyzing the downstream of daf-16, we identify that JE may regulate sod3 downstream of daf-16. Mutant worms' lifespan and transgenic reporter gene expression assays revealed that increasing SOD-3 expression was critical for extending longevity in C. elegans with JE therapy. Collectively, these data indicate that JE may have an important role in C. elegans longevity that is dependent on DAF-16 and SOD-3.

Understanding Longevity: SIN-3 and DAF-16 Revealed as Independent Players in Lifespan Regulation.

Aging is the process of gradual physio-biochemical deterioration. While aging is inevitable, healthy aging is the key to individual and communal well-being. Therefore, it is essential to understand the regulation of aging. SIN-3/Sin3 is a unique regulatory protein that regulates aging without DNA binding activity. It functions by establishing multiple protein interactions. To understand the functional mechanism of this transcriptional regulator, the Caenorhabditis elegans protein interactome was assessed for SIN-3 interactions. DAF-16/FOXO emerged as one of the leading contenders for SIN-3-mediated regulation of aging. This study looks at the concerted role of SIN-3 and DAF-16 proteins in lifespan regulation. Phenotypic profiling for the mutants of these genes shows the functional accord between these two proteins with similar functions in stress response and vital biological processes. However, there were no significant physical interactions when checked for protein-protein interaction between SIN-3 and DAF-16 proteins. C. elegans genomics and transcriptomics data also indicated the possibilities of concerted gene regulation. This genetic regulation is more likely related to SIN-3 dominance on DAF-16 function. Overall, SIN-3 and DAF-16 proteins have strong functional interactions that ensure healthy aging. The influence of SIN-3 on DAF-16 mediated stress response is one of their convergence points in longevity regulation.

SHC-3: a previously unidentified C. elegans Shc family member functions in the insulin-like signaling pathway to enhance survival during L1 arrest.

Shc proteins function in many different signaling pathways where they mediate phosphorylation-dependent protein-protein interactions. These proteins are characterized by the presence of two phosphotyrosine-binding domains, an N-terminal PTB and a C-terminal SH2. We describe a previously unrecognized C. elegans Shc gene, shc-3 and characterize its role in stress response. Both shc-3 and shc-1 are required for long-term survival in L1 arrest and survival in heat stress, however, they do not act redundantly but rather play distinct roles in these processes. Loss of shc-3 did not further decrease survival of daf-16 mutants in L1 arrest, suggesting that like SHC-1, SHC-3 functions in the Insulin-like signaling pathway. In the absence of SHC-3, DAF-16 nuclear entry and exit are slowed, suggesting that SHC-3 is required for rapid changes in DAF-16 signaling.

Developmental and conditional regulation of DAF-2/INSR ubiquitination in Caenorhabditis elegans.

Insulin/IGF signaling (IIS) regulates developmental and metabolic plasticity. Conditional regulation of insulin-like peptide expression and secretion promotes different phenotypes in different environments. However, IIS can also be regulated by other, less-understood mechanisms. For example, stability of the only known insulin/IGF receptor in C. elegans, DAF-2/INSR, is regulated by CHIP-dependent ubiquitination. Disruption of chn-1/CHIP reduces longevity in C. elegans by increasing DAF-2/INSR abundance and IIS activity in adults. Likewise, mutation of a ubiquitination site causes daf-2(gk390525) to display gain-of-function phenotypes in adults. However, we show that this allele displays loss-of-function phenotypes in larvae, and that its effect on IIS activity transitions from negative to positive during development. In contrast, the allele acts like a gain-of-function in larvae cultured at high temperature, inhibiting temperature-dependent dauer formation. Disruption of chn-1/CHIP causes an increase in IIS activity in starved L1 larvae, unlike daf-2(gk390525). CHN-1/CHIP ubiquitinates DAF-2/INSR at multiple sites. These results suggest that the sites that are functionally relevant to negative regulation of IIS vary in larvae and adults, at different temperatures, and in nutrient-dependent fashion, revealing additional layers of IIS regulation.

SPP-5 affects larval arrest via insulin signaling pathway in Caenorhabditis elegans.

Diapause is an endocrine-mediated metabolic and growth arrest state in response to unfavorable external environments. The nematode Caenorhabditis elegans can enter diapause/arrest during embryonic, larval, or adult stages when subjected to detrimental external environments. Larval stage 1 (L1) arrest happens when animals hatch without food. Previous work has shown that the insulin pathway plays a prominent role in regulating L1 arrest. However, the downstream signal molecular mechanisms and biomarkers are still missing. In this study, we showed that SaPosin-like Protein family member SPP-5 is significantly upregulated during L1 arrest, suggesting that it could act as an L1 arrest biomarker. Using RNA interference we demonstrated that spp-5  knockdown accelerated larval development, while the overexpression resulted in L1 arrest. Consistently, SPP-5 level was significantly up-regulated in the L1 arrest daf-2(e1370) mutants, and spp-5(RNAi) suppressed the daf-2(e1370) induced L1 arrest. These results suggest that SPP-5 can serve as an L1 arrest biomarker and promote the arrest probably via the insulin signaling pathway.

Inhibiting HSD17B8 suppresses the cell proliferation caused by PTEN failure.

Loss of the tumor suppressor PTEN homolog daf-18 in Caenorhabditis elegans (C. elegans) triggers diapause cell division during L1 arrest. While prior studies have delved into established pathways, our investigation takes an innovative route. Through forward genetic screening in C. elegans, we pinpoint a new player, F12E12.11, regulated by daf-18, impacting cell proliferation independently of PTEN's typical phosphatase activity. F12E12.11 is an ortholog of human estradiol 17-beta-dehydrogenase 8 (HSD17B8), which converts estradiol to estrone through its NAD-dependent 17-beta-hydroxysteroid dehydrogenase activity. We found that PTEN engages in a physical interplay with HSD17B8, introducing a distinctive suppression mechanism. The reduction in estrone levels and accumulation of estradiol may arrest tumor cells in the G2/M phase of the cell cycle through MAPK/ERK. Our study illuminates an unconventional protein interplay, providing insights into how PTEN modulates tumor suppression by restraining cell division through intricate molecular interactions.

Complement decay-accelerating factor inhibits inflammation-induced myopia development.

Myopia is regarded as a worldwide epidemic ocular disease, has been proved related to inflammation. CD55, also known as decay-accelerating factor (DAF) can modulate the activation of complement through inhibiting the formation of complement 3 convertase and its dysregulation is involved in various inflammatory diseases. To investigate the association between CD55 and myopia, and to test whether CD55 can inhibit myopia development by suppressing inflammation in the eye, we use three different animal models including monocular form-deprivation myopia, myopia induced by TNF-α administration and allergic conjunctivitis animal model to reveal the CD55 in myopia development. The tears of thirty-eight participants with different spherical equivalents were collected and CD55 in the tears were also analyzed. Complement 3 and complement 5 levels increased while CD55 levels decreased in allergic conjunctivitis and myopic eyes. After anti-inflammatory drugs administration, CD55 expression was increased in monocular form-deprivation myopia model. We also found inflammatory cytokines TGF-ß, IL-6, TNF-α, and IL-1ß may enhance complement 3 and complement 5 activation while CD55 level was suppressed contrary. Moreover, lower CD55 levels were found in the tears of patients with myopia with decreased diopter values. Finally, CD55-Fc administration on the eyelids can inhibit the elongation of axial length and change of refractive error. CD55-Fc application also suppress myopia development subsequent to complement 3 and complement 5 reduction and can lower myopia-specific (MMP-2 and TGF-ß) cytokine expression in TNF-α induced myopia animal model. This suggests that CD55 can inhibit myopia development by suppression of complement activation and eventual down-regulation of inflammation.

Angiotensin II Directly Increases Endothelial Calcium and Nitric Oxide in Kidney and Brain Microvessels In Vivo With Reduced Efficacy in Hypertension.

BACKGROUND: The vasoconstrictor effects of angiotensin II via type 1 angiotensin II receptors in vascular smooth muscle cells are well established, but the direct effects of angiotensin II on vascular endothelial cells (VECs) in vivo and the mechanisms how VECs may mitigate angiotensin II-mediated vasoconstriction are not fully understood. The present study aimed to explore the molecular mechanisms and pathophysiological relevance of the direct actions of angiotensin II on VECs in kidney and brain microvessels in vivo. METHODS AND RESULTS: Changes in VEC intracellular calcium ([Ca2+]i) and nitric oxide (NO) production were visualized by intravital multiphoton microscopy of cadherin 5-Salsa6f mice or the endothelial uptake of NO-sensitive dye 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate, respectively. Kidney fibrosis by unilateral ureteral obstruction and Ready-to-use adeno-associated virus expressing Mouse Renin 1 gene (Ren1-AAV) hypertension were used as disease models. Acute systemic angiotensin II injections triggered >4-fold increases in VEC [Ca2+]i in brain and kidney resistance arterioles and capillaries that were blocked by pretreatment with the type 1 angiotensin II receptor inhibitor losartan, but not by the type 2 angiotensin II receptor inhibitor PD123319. VEC responded to acute angiotensin II by increased NO production as indicated by >1.5-fold increase in 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate fluorescence intensity. In mice with kidney fibrosis or hypertension, the angiotensin II-induced VEC [Ca2+]i and NO responses were significantly reduced, which was associated with more robust vasoconstrictions, VEC shedding, and microthrombi formation. CONCLUSIONS: The present study directly visualized angiotensin II-induced increases in VEC [Ca2+]i and NO production that serve to counterbalance agonist-induced vasoconstriction and maintain residual organ blood flow. These direct and endothelium-specific angiotensin II effects were blunted in disease conditions and linked to endothelial dysfunction and the development of vascular pathologies.

A high-throughput screening platform for discovering bacterial species and small molecules that modify animal physiology.

The gut microbiome has been proposed to influence many aspects of animal development and physiology. However, both the specific bacterial species and the molecular mechanisms by which bacteria exert these effects are unknown in most cases. Here, we established a high throughput screening platform using the model animal Caenorhabditis elegans for identifying bacterial species and mechanisms that influence animal development and physiology. From our initial screens we found that many Bacillus species can restore normal animal development to insulin signaling mutant animals that otherwise do not develop to adulthood. To determine how Bacilli influence animal development we screened a complete non-essential gene knockout library of Bacillus subtilis for mutants that no longer restored development to adulthood. We found the Bacillus gene speB is required for animal development. In the absence of speB, B. subtilis produces excess N1-aminopropylagmatine. This polyamine is taken up by animal intestinal cells via the polyamine transporter CATP-5. When this molecule is taken up in sufficient quantities it inhibits animal mitochondrial function and causes diverse species of animals to arrest their development. To our knowledge, these are the first observations that B. subtilis can produce N1-aminopropylagmatine and that polyamines produced by intestinal microbiome species can antagonize animal development and mitochondrial function. Given that Bacilli species are regularly isolated from animal intestinal microbiomes, including from humans, we propose that altered polyamine production from intestinal Bacilli is likely to also influence animal development and metabolism in other species and potentially even contribute developmental and metabolic pathologies in humans. In addition, our findings demonstrate that C. elegans can be used as a model animal to conduct high throughput screens for bacterial species and bioactive molecules that alter animal physiology.

Pozelimab, a human monoclonal immunoglobulin for the treatment of CHAPLE disease.

The complement is a crucial factor of the innate immune system. However, its activation can lead to various diseases, so it needs to be controlled. In mammals, surface-bound complement regulatory proteins safeguard cells from uncontrolled complement-mediated lysis. One of the human complement regulators is CD55, also known as the decay-accelerating factor (DAF), a single-chain, type I cell surface protein anchored to glycosylphosphatidylinositol (GPI). The genetic loss of the complement regulatory protein CD55 leads to a fatal illness known as CHAPLE disease. The complement and innate immunity become hyperactive in this disease, causing angiopathic thrombosis and protein-losing enteropathy. Patients with CHAPLE disease experience abdominal pain, nausea, vomiting, diarrhea, loss of appetite, weight loss, impaired growth, and swelling. This genetic condition has no known cure, and managing its symptoms can be challenging. Pozelimab, a human monoclonal immunoglobulin IgG4 antibody, is a drug that targets the terminal complement protein C5. The drug has a high affinity for both wild-type and variant human C5. Pozelimab has received designations such as fast track, orphan drug, and rare pediatric disease, making it a significant medical breakthrough. It is currently the only available treatment for this disease. In this review, we have summarized the preclinical and clinical data on pozelimab.

Ovalbumin promotes innate immune response of Caenorhabditis elegans through DAF-16 and SKN-1 pathways in insulin/IGF-1 signaling.

Ovalbumin (OVA) is a major allergen in eggs and could induce severe allergic reactions in sensitive individuals, where the innate immune system works as a regulator. The mechanism of how innate immunity adjusts to food allergy is relatively well-studied, however, the effects of allergen uptake on the innate immune system remain unclear. Therefore, the Caenorhabditis elegans (C. elegans) model was utilized to assess the effects of OVA on its innate immune system. OVA enhanced the immune response of C. elegans with higher survival rates under Pseudomonas aeruginosa infection. Moreover, sustaining OVA treatment improved the health states that were reflected in the prolonged lifespan, alleviated oxidative stress, accelerated growth, and promoted motility. RNA-sequencing analysis and the slow-killing assays in the mutants of insulin/IGF-1 signaling (IIS)-related genes confirmed that IIS was necessary for OVA to regulate innate immunity. Besides, OVA activated SKN-1 temporarily and facilitated the nuclear localization of DAF-16 for improving immunity and health status in C. elegans. Together, OVA could enhance the innate immune responses via DAF-16 and SKN-1 pathways in the IIS of C. elegans, and this work will provide novel insights into the regulation of innate immunity by OVA in higher organisms.

Oocyte mitochondria link maternal environment to offspring phenotype.

During maturation oocytes undergo a recently discovered mitochondrial proteome remodeling event in flies1, frogs1, and humans2. This oocyte mitochondrial remodeling, which includes substantial changes in electron transport chain (ETC) subunit abundance1,2, is regulated by maternal insulin signaling1. Why oocytes undergo mitochondrial remodeling is unknown, with some speculating that it might be an evolutionarily conserved mechanism to protect oocytes from genotoxic damage by reactive oxygen species (ROS)2. In Caenorhabditis elegans, we previously found that maternal exposure to osmotic stress drives a 50-fold increase in offspring survival in response to future osmotic stress3. Like mitochondrial remodeling, we found that this intergenerational adaptation is also regulated by insulin signaling to oocytes3. Here, we used proteomics and genetic manipulations to show that insulin signaling to oocytes regulates offspring's ability to adapt to future stress via a mechanism that depends on ETC composition in maternal oocytes. Specifically, we found that maternally expressed mutant alleles of nduf-7 (complex I subunit) or isp-1 (complex III subunit) altered offspring's response to osmotic stress at hatching independently of offspring genotype. Furthermore, we found that expressing wild-type isp-1 in germ cells (oocytes) was sufficient to restore offspring's normal response to osmotic stress. Chemical mutagenesis screens revealed that maternal ETC composition regulates offspring's response to stress by altering AMP kinase function in offspring which in turn regulates both ATP and glycerol metabolism in response to continued osmotic stress. To our knowledge, these data are the first to show that proper oocyte ETC composition is required to link a mother's environment to adaptive changes in offspring metabolism. The data also raise the possibility that the reason diverse animals exhibit insulin regulated remodeling of oocyte mitochondria is to tailor offspring metabolism to best match the environment of their mother.

A 21-bp deletion in the complement regulator CD55 promotor region is associated with multifocal motor neuropathy and its disease course.

BACKGROUND AND AIMS: To further substantiate the role of antibody-mediated complement activation in multifocal motor neuropathy (MMN) immunopathology, we investigated the distribution of promotor polymorphisms of genes encoding the membrane-bound complement regulators CD46, CD55, and CD59 in patients with MMN and controls, and evaluated their association with disease course. METHODS: We used Sanger sequencing to genotype five common polymorphisms in the promotor regions of CD46, CD55, and CD59 in 133 patients with MMN and 380 controls. We correlated each polymorphism to clinical parameters. RESULTS: The genotype frequencies of rs28371582, a 21-bp deletion in the CD55 promotor region, were altered in patients with MMN as compared to controls (p .009; Del/Del genotype 16.8% vs. 7.7%, p .005, odds ratio: 2.43 [1.27-4.58]), and patients carrying this deletion had a more favorable disease course (mean difference 0.26 Medical Research Council [MRC] points/year; 95% confidence interval [CI]: 0.040-0.490, p .019). The presence of CD59 rs141385724 was associated with less severe pre-diagnostic disease course (mean difference 0.940 MRC point/year; 95% CI: 0.083-1.80, p .032). INTERPRETATION: MMN susceptibility is associated with a 21-bp deletion in the CD55 promotor region (rs2871582), which is associated with lower CD55 expression. Patients carrying this deletion may have a more favorable long-term disease outcome. Taken together, these results point out the relevance of the pre-C5 level of the complement cascade in the inflammatory processes underlying MMN.

Combinatorial transcriptomic and genetic dissection of insulin/IGF-1 signaling-regulated longevity in Caenorhabditis elegans.

Classical genetic analysis is invaluable for understanding the genetic interactions underlying specific phenotypes, but requires laborious and subjective experiments to characterize polygenic and quantitative traits. Contrarily, transcriptomic analysis enables the simultaneous and objective identification of multiple genes whose expression changes are associated with specific phenotypes. Here, we conducted transcriptomic analysis of genes crucial for longevity using datasets with daf-2/insulin/IGF-1 receptor mutant Caenorhabditis elegans. Our analysis unraveled multiple epistatic relationships at the transcriptomic level, in addition to verifying genetically established interactions. Our combinatorial analysis also revealed transcriptomic changes associated with longevity conferred by daf-2 mutations. In particular, we demonstrated that the extent of lifespan changes caused by various mutant alleles of the longevity transcription factor daf-16/FOXO matched their effects on transcriptomic changes in daf-2 mutants. We identified specific aging-regulating signaling pathways and subsets of structural and functional RNA elements altered by different genes in daf-2 mutants. Lastly, we elucidated the functional cooperation between several longevity regulators, based on the combination of transcriptomic and molecular genetic analysis. These data suggest that different biological processes coordinately exert their effects on longevity in biological networks. Together our work demonstrates the utility of transcriptomic dissection analysis for identifying important genetic interactions for physiological processes, including aging and longevity.

Dendrobium Nobile Alcohol Extract Extends the Lifespan of Caenorhabditis elegans via hsf-1 and daf-16.

Dendrobium nobile is a traditional Chinese herb with anti-inflammatory, antioxidant, and neuroprotective properties. However, its antiaging effects are unclear. Herein, we studied the aging-related functions and the mechanism of action of the alcohol extract of Dendrobium nobile (DnAE) in the model organism Caenorhabditis elegans. The results indicated that 1 mg/mL DnAE slowed lipofuscin accumulation, decreased the levels of reactive oxygen species, elevated superoxide dismutase activity, enhanced oxidative and heat stress resistance, extended the lifespan of nematodes, protected their dopamine neurons from 6-hydroxydopamine-induced neurodegeneration, and reduced Aß-induced neurotoxicity. DnAE upregulated the mRNA expression of the transcription factors DAF-16 and HSF-1, promoted the nuclear localization of DAF-16, and enhanced the fluorescence intensity of HSP-16.2. However, it had no effect on the lifespan of DAF-16 mutants. Thus, DnAE can significantly extend lifespan, enhance heat stress tolerance, and delay age-related diseases through a DAF-16-dependent pathway.

Considering Caenorhabditis elegans Aging on a Temporal and Tissue Scale: The Case of Insulin/IGF-1 Signaling.

The aging process is inherently complex, involving multiple mechanisms that interact at different biological scales. The nematode Caenorhabditis elegans is a simple model organism that has played a pivotal role in aging research following the discovery of mutations extending lifespan. Longevity pathways identified in C. elegans were subsequently found to be conserved and regulate lifespan in multiple species. These pathways intersect with fundamental hallmarks of aging that include nutrient sensing, epigenetic alterations, proteostasis loss, and mitochondrial dysfunction. Here we summarize recent data obtained in C. elegans highlighting the importance of studying aging at both the tissue and temporal scale. We then focus on the neuromuscular system to illustrate the kinetics of changes that take place with age. We describe recently developed tools that enabled the dissection of the contribution of the insulin/IGF-1 receptor ortholog DAF-2 to the regulation of worm mobility in specific tissues and at different ages. We also discuss guidelines and potential pitfalls in the use of these new tools. We further highlight the opportunities that they present, especially when combined with recent transcriptomic data, to address and resolve the inherent complexity of aging. Understanding how different aging processes interact within and between tissues at different life stages could ultimately suggest potential intervention points for age-related diseases.

The ACE inhibitor captopril inhibits ACN-1 to control dauer formation and aging.

The renin-angiotensin-aldosterone system (RAAS) plays a well-characterized role regulating blood pressure in mammals. Pharmacological and genetic manipulation of the RAAS has been shown to extend lifespan in Caenorhabditis elegans, Drosophila and rodents, but its mechanism is not well defined. Here, we investigate the angiotensin-converting enzyme (ACE) inhibitor drug captopril, which extends lifespan in worms and mice. To investigate the mechanism, we performed a forward genetic screen for captopril-hypersensitive mutants. We identified a missense mutation that causes a partial loss of function of the daf-2 receptor tyrosine kinase gene, a powerful regulator of aging. The homologous mutation in the human insulin receptor causes Donohue syndrome, establishing these mutant worms as an invertebrate model of this disease. Captopril functions in C. elegans by inhibiting ACN-1, the worm homolog of ACE. Reducing the activity of acn-1 via captopril or RNA interference promoted dauer larvae formation, suggesting that acn-1 is a daf gene. Captopril-mediated lifespan extension was abrogated by daf-16(lf) and daf-12(lf) mutations. Our results indicate that captopril and acn-1 influence lifespan by modulating dauer formation pathways. We speculate that this represents a conserved mechanism of lifespan control.

Insulin signaling in dopaminergic neurons regulates extended memory formation in Caenorhabditis elegans.

Insulin alters several brain functions, and perturbations in insulin levels could be a precipitating factor for Parkinson's disease, a disease associated with the degeneration of dopaminergic neurons. It is unclear whether insulin alters the dopamine signaling pathway and modulates learning and memory. In Caenorhabditis elegans, daf-2 insulin receptor mutants have extended memory when trained for olfactory adaptation. In this study, we show that the absence of daf-2 receptors in dopamine neurons results in this unusual learning behavior. Our results show that insulin function in memory is dopamine-dependent. In the absence of the daf-2 receptor, the calcium influx in dopamine neurons shows an altered pattern resulting in memory recall for an extended period. These results indicate that learning and memory involve insulin-dopamine crosstalk. Imbalances in this pathway result in changes in memory recall.