Metformin retards aging in C. elegans by altering microbial folate and methionine metabolism.

The biguanide drug metformin is widely prescribed to treat type 2 diabetes and metabolic syndrome, but its mode of action remains uncertain. Metformin also increases lifespan in Caenorhabditis elegans cocultured with Escherichia coli. This bacterium exerts complex nutritional and pathogenic effects on its nematode predator/host that impact health and aging. We report that metformin increases lifespan by altering microbial folate and methionine metabolism. Alterations in metformin-induced longevity by mutation of worm methionine synthase (metr-1) and S-adenosylmethionine synthase (sams-1) imply metformin-induced methionine restriction in the host, consistent with action of this drug as a dietary restriction mimetic. Metformin increases or decreases worm lifespan, depending on E. coli strain metformin sensitivity and glucose concentration. In mammals, the intestinal microbiome influences host metabolism, including development of metabolic disease. Thus, metformin-induced alteration of microbial metabolism could contribute to therapeutic efficacy-and also to its side effects, which include folate deficiency and gastrointestinal upset.

De Novo Variants Disturbing the Transactivation Capacity of POU3F3 Cause a Characteristic Neurodevelopmental Disorder.

POU3F3, also referred to as Brain-1, is a well-known transcription factor involved in the development of the central nervous system, but it has not previously been associated with a neurodevelopmental disorder. Here, we report the identification of 19 individuals with heterozygous POU3F3 disruptions, most of which are de novo variants. All individuals had developmental delays and/or intellectual disability and impairments in speech and language skills. Thirteen individuals had characteristic low-set, prominent, and/or cupped ears. Brain abnormalities were observed in seven of eleven MRI reports. POU3F3 is an intronless gene, insensitive to nonsense-mediated decay, and 13 individuals carried protein-truncating variants. All truncating variants that we tested in cellular models led to aberrant subcellular localization of the encoded protein. Luciferase assays demonstrated negative effects of these alleles on transcriptional activation of a reporter with a FOXP2-derived binding motif. In addition to the loss-of-function variants, five individuals had missense variants that clustered at specific positions within the functional domains, and one small in-frame deletion was identified. Two missense variants showed reduced transactivation capacity in our assays, whereas one variant displayed gain-of-function effects, suggesting a distinct pathophysiological mechanism. In bioluminescence resonance energy transfer (BRET) interaction assays, all the truncated POU3F3 versions that we tested had significantly impaired dimerization capacities, whereas all missense variants showed unaffected dimerization with wild-type POU3F3. Taken together, our identification and functional cell-based analyses of pathogenic variants in POU3F3, coupled with a clinical characterization, implicate disruptions of this gene in a characteristic neurodevelopmental disorder.

Tuning the properties of a cyclic RGD-containing tetrapeptide through backbone fluorination.

Stereoselective fluorination is investigated as a method for modulating the properties of a cyclic RGD-containing tetrapeptide. Three key outcomes of fluorination are assessed: (i) the effect on peptide cyclisation efficiency; (ii) the ability to fine-tune the molecular conformation; and (iii) the effect on the cyclic peptides' biological activity. Fluorination is found to exert pronounced effects against all three criteria.

Proteomics Identifies Golgi phosphoprotein 3 (GOLPH3) with A Link Between Golgi Structure, Cancer, DNA Damage and Protection from Cell Death.

GOLPH3 is the first example of a Golgi resident oncogene protein. It was independently identified in multiple screens; first in proteomic-based screens as a resident protein of the Golgi apparatus, and second as an oncogene product in a screen for genes amplified in cancer. A third screen uncovered the association of GOLPH3 with the Golgi resident phospholipid, phosphatidyl inositol 4 phosphate (PI4P) to maintain the characteristic ribbon structure of the Golgi apparatus favoring vesicular transport of secretory proteins.

Absence of effects of Sir2 overexpression on lifespan in C. elegans and Drosophila.

Overexpression of sirtuins (NAD(+)-dependent protein deacetylases) has been reported to increase lifespan in budding yeast (Saccharomyces cerevisiae), Caenorhabditis elegans and Drosophila melanogaster. Studies of the effects of genes on ageing are vulnerable to confounding effects of genetic background. Here we re-examined the reported effects of sirtuin overexpression on ageing and found that standardization of genetic background and the use of appropriate controls abolished the apparent effects in both C. elegans and Drosophila. In C. elegans, outcrossing of a line with high-level sir-2.1 overexpression abrogated the longevity increase, but did not abrogate sir-2.1 overexpression. Instead, longevity co-segregated with a second-site mutation affecting sensory neurons. Outcrossing of a line with low-copy-number sir-2.1 overexpression also abrogated longevity. A Drosophila strain with ubiquitous overexpression of dSir2 using the UAS-GAL4 system was long-lived relative to wild-type controls, as previously reported, but was not long-lived relative to the appropriate transgenic controls, and nor was a new line with stronger overexpression of dSir2. These findings underscore the importance of controlling for genetic background and for the mutagenic effects of transgene insertions in studies of genetic effects on lifespan. The life-extending effect of dietary restriction on ageing in Drosophila has also been reported to be dSir2 dependent. We found that dietary restriction increased fly lifespan independently of dSir2. Our findings do not rule out a role for sirtuins in determination of metazoan lifespan, but they do cast doubt on the robustness of the previously reported effects of sirtuins on lifespan in C. elegans and Drosophila.

DAF-16/FoxO directly regulates an atypical AMP-activated protein kinase gamma isoform to mediate the effects of insulin/IGF-1 signaling on aging in Caenorhabditis elegans.

The DAF-16/FoxO transcription factor controls growth, metabolism and aging in Caenorhabditis elegans. The large number of genes that it regulates has been an obstacle to understanding its function. However, recent analysis of transcript and chromatin profiling implies that DAF-16 regulates relatively few genes directly, and that many of these encode other regulatory proteins. We have investigated the regulation by DAF-16 of genes encoding the AMP-activated protein kinase (AMPK), which has α, ß and γ subunits. C. elegans has 5 genes encoding putative AMP-binding regulatory γ subunits, aakg-1-5. aakg-4 and aakg-5 are closely related, atypical isoforms, with orthologs throughout the Chromadorea class of nematodes. We report that ∼75% of total γ subunit mRNA encodes these 2 divergent isoforms, which lack consensus AMP-binding residues, suggesting AMP-independent kinase activity. DAF-16 directly activates expression of aakg-4, reduction of which suppresses longevity in daf-2 insulin/IGF-1 receptor mutants. This implies that an increase in the activity of AMPK containing the AAKG-4 γ subunit caused by direct activation by DAF-16 slows aging in daf-2 mutants. Knock down of aakg-4 expression caused a transient decrease in activation of expression in multiple DAF-16 target genes. This, taken together with previous evidence that AMPK promotes DAF-16 activity, implies the action of these two metabolic regulators in a positive feedback loop that accelerates the induction of DAF-16 target gene expression. The AMPK ß subunit, aakb-1, also proved to be up-regulated by DAF-16, but had no effect on lifespan. These findings reveal key features of the architecture of the gene-regulatory network centered on DAF-16, and raise the possibility that activation of AMP-independent AMPK in nutritionally replete daf-2 mutant adults slows aging in C. elegans. Evidence of activation of AMPK subunits in mammals suggests that such FoxO-AMPK interactions may be evolutionarily conserved.

Introduction of the Nurse Endoscopist Role in One Australian Health Service.

In Australia, nurses performing endoscopic procedures is a recent phenomenon and is uncommon. Challenges include gastroenterologist and patient acceptance of the nurse endoscopist role. This article aims to explore Monash Health's experience with the introduction of a nurse endoscopist. A nurse endoscopist trainee undertook a comprehensive training program under the supervision of a gastroenterologist. All procedural data were collected, organizational policy and procedures were developed, and patients (n = 40) completed a telephone interview postprocedure. The nurse endoscopist trainee completed all training requirements during the 12-month program and was deemed competent for independent practice. The trainee performed 255 colonoscopies, with no complications reported. The organization successfully implemented the expanded scope of practice, established a new model of care for patients, and initiated a governance framework for this advanced practice role. Eighty percent of patients (n = 32) reported that overall, they had a very good experience with the nurse endoscopist trainee. A nurse endoscopist initiative can facilitate the expansion of endoscopy services to meet the growing need for gastroenterological procedures within the community. This pilot program has demonstrated that it is possible to integrate an advanced practice nurse role into an established endoscopy unit.

Organellar proteomics to create the cell map.

The elucidation of a complete, accurate, and permanent representation of the proteome of the mammalian cell may be achievable piecemeal by an organellar based approach. The small volume of organelles assures high protein concentrations. Providing isolated organelles are homogenous, this assures reliable protein characterization within the sensitivity and dynamic range limits of current mass spec based analysis. The stochastic aspect of peptide selection by tandem mass spectrometry for sequence determination by fragmentation is dealt with by multiple biological replicates as well as by prior protein separation on 1-D gels. Applications of this methodology to isolated synaptic vesicles, clathrin coated vesicles, endosomes, phagosomes, endoplasmic reticulum, and Golgi apparatus, as well as Golgi-derived COPI vesicles, have led to mechanistic insight into the identity and function of these organelles.

Extracellular dopamine potentiates mn-induced oxidative stress, lifespan reduction, and dopaminergic neurodegeneration in a BLI-3-dependent manner in Caenorhabditis elegans.

Parkinson's disease (PD)-mimicking drugs and pesticides, and more recently PD-associated gene mutations, have been studied in cell cultures and mammalian models to decipher the molecular basis of PD. Thus far, a dozen of genes have been identified that are responsible for inherited PD. However they only account for about 8% of PD cases, most of the cases likely involving environmental contributions. Environmental manganese (Mn) exposure represents an established risk factor for PD occurrence, and both PD and Mn-intoxicated patients display a characteristic extrapyramidal syndrome primarily involving dopaminergic (DAergic) neurodegeneration with shared common molecular mechanisms. To better understand the specificity of DAergic neurodegeneration, we studied Mn toxicity in vivo in Caenorhabditis elegans. Combining genetics and biochemical assays, we established that extracellular, and not intracellular, dopamine (DA) is responsible for Mn-induced DAergic neurodegeneration and that this process (1) requires functional DA-reuptake transporter (DAT-1) and (2) is associated with oxidative stress and lifespan reduction. Overexpression of the anti-oxidant transcription factor, SKN-1, affords protection against Mn toxicity, while the DA-dependency of Mn toxicity requires the NADPH dual-oxidase BLI-3. These results suggest that in vivo BLI-3 activity promotes the conversion of extracellular DA into toxic reactive species, which, in turn, can be taken up by DAT-1 in DAergic neurons, thus leading to oxidative stress and cell degeneration.

Referrals to hospital emergency departments from residential aged care facilities: stuck in a time warp.

This research aimed to describe the number and type of residents admitted to emergency departments (EDs) over 2 years; and to explore nurses' perceptions of the reasons why residential aged care facility (RACF) residents are referred to EDs. The research objective was addressed in a retrospective exploratory study using data on admissions to EDs from RACFs (N = 3,094) at the participating organisation over a 2-year period, and interview data on seven RACF and four ED nurses' perceptions of the issues involved. Most residents presenting at EDs required urgent medical attention. Major themes identified by RACF and ED nurses included issues related to staff competency, availability of general practitioners, lack of equipment in RACFs, residents and family members requesting referrals, communication difficulties, and poor attitudes towards RACF staff. There is a need to use strategies to detect residents whose conditions are deteriorating and treat them promptly in RACFs.

A HUPO test sample study reveals common problems in mass spectrometry-based proteomics.

We performed a test sample study to try to identify errors leading to irreproducibility, including incompleteness of peptide sampling, in liquid chromatography-mass spectrometry-based proteomics. We distributed an equimolar test sample, comprising 20 highly purified recombinant human proteins, to 27 laboratories. Each protein contained one or more unique tryptic peptides of 1,250 Da to test for ion selection and sampling in the mass spectrometer. Of the 27 labs, members of only 7 labs initially reported all 20 proteins correctly, and members of only 1 lab reported all tryptic peptides of 1,250 Da. Centralized analysis of the raw data, however, revealed that all 20 proteins and most of the 1,250 Da peptides had been detected in all 27 labs. Our centralized analysis determined missed identifications (false negatives), environmental contamination, database matching and curation of protein identifications as sources of problems. Improved search engines and databases are needed for mass spectrometry-based proteomics.

A human cell-based reporter detects microhomology-mediated end joining.

DNA double-strand breaks (DSBs) are most often repaired by two pathways in mammalian cells, homologous recombination or non-homologous end joining. Biochemical and genetic studies showed that DSBs can also be joined via microhomology-mediated end joining (MHEJ), which is always mutagenic and may result in diseases, such as cancer. In this study we established a human cell-based reporter system to determine the prevalence of MHEJ events and factors that modulate MHEJ. A nonfunctional puromycin acetyltransferase (Pac) gene, disrupted by an insertion flanked by two microhomologous repeats, was integrated into chromosomes of human HT1080 cells. Repair of DSBs via MHEJ using the repeats resulted in deletion of the insertion and restoration of the Pac gene function, thus rendering the cells puromycin resistant. Our results showed that MHEJ spontaneously occurs at the reporter locus (loci), manifested by formation of puromycin resistant (puro(r)) colonies after culturing reporter cells in medium containing puromycin. The frequency of puro(r) cells can be greatly increased by site-directed DSB inside the insertion. Our results also demonstrated that the frequency of puro(r) cells is affected by the length of the repeat and by the size of the intervening sequence. Thus, this cell-based assay provides a platform for evaluating factors modulating in vivo MHEJ.

Impact of patient education videos on genetic counseling outcomes after exome sequencing.

OBJECTIVE: Growing use of clinical exome sequencing (CES) has led to an increased burden of genomic education. Self-guided educational tools can minimize the educational burden for genetic counselors (GCs). The effectiveness of these tools must be evaluated. METHODS: Parents of patients offered CES were randomized to watch educational videos before their visit or to receive routine care. Parents and GCs were surveyed about their experiences following the sessions. The responses of the video (n = 102) and no-video (n = 105) groups were compared. RESULTS: GCs reported no significant differences between parents in the video and no-video groups on genetics knowledge or CES knowledge. In contrast, parents' scores on genetics knowledge questions were lower in the video than no-video group (p = 0.007). Most parents reported the videos were informative, and the groups did not differ in satisfaction with GCs or decisions to have CES. CONCLUSION: GCs and parents perceived the videos to be beneficial. However, lower scores on genetics knowledge questions highlight the need for careful development of educational tools. PRACTICE IMPLICATIONS: Educational tools should be developed and assessed for effectiveness with the input of all stakeholders before widespread implementation. Better measures of the effectiveness of these educational tools are needed.

Production of YP170 Vitellogenins Promotes Intestinal Senescence in Caenorhabditis elegans.

During aging, etiologies of senescence cause multiple pathologies, leading to morbidity and death. To understand aging requires identification of these etiologies. For example, Caenorhabditis elegans hermaphrodites consume their own intestinal biomass to support yolk production, which in later life drives intestinal atrophy and ectopic yolk deposition. Yolk proteins (YPs; vitellogenins) exist as three abundant species: YP170, derived from vit-1-vit-5; and YP115 and YP88, derived from vit-6. Here, we show that inhibiting YP170 synthesis leads to a reciprocal increase in YP115/YP88 levels and vice versa, an effect involving posttranscriptional mechanisms. Inhibiting YP170 production alone, despite increasing YP115/YP88 synthesis, reduces intestinal atrophy as much as inhibition of all YP synthesis, which increases life span. By contrast, inhibiting YP115/YP88 production alone accelerates intestinal atrophy and reduces life span, an effect that is dependent on increased YP170 production. Thus, despite copious abundance of both YP170 and YP115/YP88, only YP170 production is coupled to intestinal atrophy and shortened life span. In addition, increasing levels of YP115/YP88 but not of YP170 increases resistance to oxidative stress; thus, longevity resulting from reduced vitellogenin synthesis is not attributable to oxidative stress resistance.

New label-free automated survival assays reveal unexpected stress resistance patterns during C. elegans aging.

Caenorhabditis elegans is an excellent model for high-throughput experimental approaches but lacks an automated means to pinpoint time of death during survival assays over a short time frame, that is, easy to implement, highly scalable, robust, and versatile. Here, we describe an automated, label-free, high-throughput method using death-associated fluorescence to monitor nematode population survival (dubbed LFASS for label-free automated survival scoring), which we apply to severe stress and infection resistance assays. We demonstrate its use to define correlations between age, longevity, and severe stress resistance, and its applicability to parasitic nematodes. The use of LFASS to assess the effects of aging on susceptibility to severe stress revealed an unexpected increase in stress resistance with advancing age, which was largely autophagy-dependent. Correlation analysis further revealed that while severe thermal stress resistance positively correlates with lifespan, severe oxidative stress resistance does not. This supports the view that temperature-sensitive protein-handling processes more than redox homeostasis underpin aging in C. elegans. That the ages of peak resistance to infection, severe oxidative stress, heat shock, and milder stressors differ markedly suggests that stress resistance and health span do not show a simple correspondence in C. elegans.

Antioxidants prevent the cytotoxicity of manganese in RBE4 cells.

Manganese (Mn) is an essential trace element required for ubiquitous enzymatic reactions. Chronic overexposure to this metal may, however, promote potent neurotoxic effects. The mechanism of Mn toxicity is not well established, but several studies indicate that oxidative stress and mitochondria play major roles in the Mn-induced neurodegenerative processes that lead to dysfunction in the basal ganglia. The aim of this study was to address the toxic effects of MnCl2 and MnSO4 on the immortalized rat brain microvessel endothelial cell line (RBE4) and to characterize toxic mechanism associated with exposure to Mn. The cytotoxicity of Mn in RBE4 cells was evaluated using the LDH and the MTT assays. A significant increase was noted in LDH release from RBE4 cells exposed for 24 h to MnCl2 at concentrations of 800 microM and MnSO4 at concentrations > or = 400 microM (p < 0.05) when compared with control unexposed cells. The MTT assay established significant decrease in cellular viability upon exposure to MnCl2 at concentrations > or = 100 microM and to MnSO4 at concentrations > or = 50 microM (p < 0.05). Thus, the cytotoxicity assays showed that the MTT assay was more sensitive than the LDH assay, suggesting that mitochondrial changes precede other toxic effects of Mn. In addition, upon exposure to MnCl2 (200 and 800 microM), intracellular reduced glutathione (GSH) levels in RBE4 cells decreased as Mn exposure concentrations increased (p < 0.05). To confirm the oxidative hypothesis of Mn cytotoxicity, co-exposure of MnCl2 with antioxidant agents (N-acetylcysteine [NAC] or Trolox) were carried out. The cellular viability was evaluated using the MTT assay. A significant decrease in Mn cytotoxicity was observed in co-exposed cells confirming that (1) oxidative stress plays a critical role in the mechanism of Mn toxicity, and (2) antioxidants may offer a useful therapeutic modality to reverse the aberrant effects of Mn.

Manganese transport in eukaryotes: the role of DMT1.

Manganese (Mn) is a transition metal that is essential for normal cell growth and development, but is toxic at high concentrations. While Mn deficiency is uncommon in humans, Mn toxicity is known to be readily prevalent due to occupational overexposure in miners, smelters and possibly welders. Excessive exposure to Mn can cause Parkinson's disease-like syndrome; patients typically exhibit extrapyramidal symptoms that include tremor, rigidity and hypokinesia [Calne DB, Chu NS, Huang CC, Lu CS, Olanow W. Manganism and idiopathic parkinsonism: similarities and differences. Neurology 1994;44(9):1583-6; Dobson AW, Erikson KM, Aschner M. Manganese neurotoxicity. Ann NY Acad Sci 2004;1012:115-28]. Mn-induced motor neuron diseases have been the subjects of numerous studies; however, this review is not intended to discuss its neurotoxic potential or its role in the etiology of motor neuron disorders. Rather, it will focus on Mn uptake and transport via the orthologues of the divalent metal transporter (DMT1) and its possible implications to Mn toxicity in various categories of eukaryotic systems, such as in vitro cell lines, in vivo rodents, the fruitfly, Drosophila melanogaster, the honeybee, Apis mellifera L., the nematode, Caenorhabditis elegans and the baker's yeast, Saccharomyces cerevisiae.

C. elegans Eats Its Own Intestine to Make Yolk Leading to Multiple Senescent Pathologies.

Aging (senescence) is characterized by the development of numerous pathologies, some of which limit lifespan. Key to understanding aging is discovery of the mechanisms (etiologies) that cause senescent pathology. In C. elegans, a major senescent pathology of unknown etiology is atrophy of its principal metabolic organ, the intestine. Here we identify a cause of not only this pathology but also of yolky lipid accumulation and redistribution (a form of senescent obesity): autophagy-mediated conversion of intestinal biomass into yolk. Inhibiting intestinal autophagy or vitellogenesis rescues both visceral pathologies and can also extend lifespan. This defines a disease syndrome leading to multimorbidity and contributing to late-life mortality. Activation of gut-to-yolk biomass conversion by insulin/IGF-1 signaling (IIS) promotes reproduction and senescence. This illustrates how major, IIS-promoted senescent pathologies in C. elegans can originate not from damage accumulation but from direct effects of futile, continued action of a wild-type biological program (vitellogenesis).

Effects of nanoparticles on the adhesion and cell viability on astrocytes.

In recent years, both pharmaceutical companies and manufacturing industries have expressed heightened interest in the potential applications of magnetic nanoparticles for therapeutic and technological purposes. Specifically, pharmaceutical companies seek to employ magnetic nanoparticles as carriers to facilitate effective drug delivery, especially in areas of the brain. Manufacturing industries desire to use these nanoparticles as ferrofluids and in magnetic resonance imaging. However, data concerning the effects of magnetic nanoparticles on the nervous system is limited. This study tested the hypotheses that nanoparticles can (1) inhibit adherence of astrocytes to culture plates and (2) cause cytotoxicity or termination of growth, both end points representing surrogate markers of neurotoxicity. Using light microscopy, changes in plating patterns were determined by visual assessment. Cell counting 4 days after plating revealed a significant decrease in the number of viable astrocytes in nanoparticle treated groups (p < 0.0001). To determine the cytotoxic effects of nanoparticles, astrocytes were allowed to adhere to culture plates and grow to maturity for 3 weeks before treatment. Membrane integrity and mitochondrial function were measured using colorimetric analysis lactate dehydrogenase (LDH) and 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTS), respectively. Treatment with nanoparticles did not significantly alter astrocytic LDH release (p > 0.05) in the control group (100% +/- 1.56) vs the group receiving treatment (97.18% +/- 2.03). However, a significant increase in MTS activity (p < 0.05) between the control (100% +/- 3.65) and treated groups (112.8% +/- 3.23) was observed, suggesting astrocytic mitochondrial uncoupling by nanoparticles. These data suggest that nanoparticles impede the attachment of astrocytes to the substratum. However, once astrocytes attach to the substratum and grow to confluence, nanoparticles may cause mitochondrial stress.

The SKN-1/Nrf2 transcription factor can protect against oxidative stress and increase lifespan in C. elegans by distinct mechanisms.

In C. elegans, the skn-1 gene encodes a transcription factor that resembles mammalian Nrf2 and activates a detoxification response. skn-1 promotes resistance to oxidative stress (Oxr) and also increases lifespan, and it has been suggested that the former causes the latter, consistent with the theory that oxidative damage causes aging. Here, we report that effects of SKN-1 on Oxr and longevity can be dissociated. We also establish that skn-1 expression can be activated by the DAF-16/FoxO transcription factor, another central regulator of growth, metabolism, and aging. Notably, skn-1 is required for Oxr but not increased lifespan resulting from over-expression of DAF-16; concomitantly, DAF-16 over-expression rescues the short lifespan of skn-1 mutants but not their hypersensitivity to oxidative stress. These results suggest that SKN-1 promotes longevity by a mechanism other than protection against oxidative damage.