Silver electroceutical technology to treat sarcopenia.

While the world is rapidly transforming into a superaging society, pharmaceutical approaches to treat sarcopenia have hitherto not been successful due to their insufficient efficacy and failure to specifically target skeletal muscle cells (skMCs). Although electrical stimulation (ES) is emerging as an alternative intervention, its efficacy toward treating sarcopenia remains unexplored. In this study, we demonstrate a silver electroceutical technology with the potential to treat sarcopenia. First, we developed a high-throughput ES screening platform that can simultaneously stimulate 15 independent conditions, while utilizing only a small number of human-derived primary aged/young skMCs (hAskMC/hYskMC). The in vitro screening showed that specific ES conditions induced hypertrophy and rejuvenation in hAskMCs, and the optimal ES frequency in hAskMCs was different from that in hYskMCs. When applied to aged mice in vivo, specific ES conditions improved the prevalence and thickness of Type IIA fibers, along with biomechanical attributes, toward a younger skMC phenotype. This study is expected to pave the way toward an electroceutical treatment for sarcopenia with minimal side effects and help realize personalized bioelectronic medicine.

Laparoscopic left hemihepatectomy using the extrahepatic Glissonean approach: Technical tips for entering gaps.

There are two methods for selective inflow control from the liver hilum: individual hilar dissection and the Glissonean pedicle approach. The Glissonean pedicle approach has been increasingly used in laparoscopic anatomical liver resection. Recently, the extrahepatic Glissonean approach has been standardized due to the anatomical concept of Laennec's capsule. This article describes the technical details of entering gaps between the Laennec's capsule and Glissonean pedicle in laparoscopic left hemihepatectomy using the extrahepatic Glissonean approach. The key procedures of the laparoscopic left hemihepatectomy using the extrahepatic Glissonean approach included the following: (1) Dissection of left side of the hilar plate, (2) Dissection of ventral side of caudal end of the Arantius ligament, (3) Dissection and transection of left Glissonean pedicle. Our standardized technique is to create gap between the Laennec's capsule and Glissonean pedicle through appropriate traction and countertraction at the anatomical landmarks. Our procedure helps the surgeons to reproduce the extrahepatic Glissonean approach without parenchymal transection.

Laparoscopic Left Hemihepatectomy Using the Hilar Plate-First Approach (with Video).

BACKGROUND: Effective inflow and outflow control of the liver is essential for a safe hepatectomy. Detachment of the hilar plate is a fundamental technique in the Glissonean approach. The hilar plate is situated near the middle hepatic vein, which runs in the midplane of the liver, and serves as a landmark during hemihepatectomy. In this study, we describe the technical details and surgical outcomes of laparoscopic left hemihepatectomy using the hilar plate-first approach. METHODS: The key procedures of the hilar plate-first approach included the following: (1) detachment of the hilar plate for the left Glissonean approach, (2) the middle hepatic vein approach from the hilar plate, (3) parenchymal transection along the ischemic line and middle hepatic vein, and (4) transection of the left Glissonean pedicle at the ventral aspect of the Arantius ligament. RESULTS: Between September 2020 and September 2021, 12 patients underwent laparoscopic left hemihepatectomy using the hilar plate-first approach. The median operation time was 227 min (range 140-350 min), and the median estimated blood loss was 82.5 ml (range 50-150 ml). The median length of postoperative hospital stay was 7 days (range 5-10 days). No major complications, including biliary complications, were observed. CONCLUSION: The hilar plate-first approach contributes to the standardization of surgical techniques for laparoscopic left hemihepatectomy. This technique is a safe and effective approach for the inflow and outflow systems of the left hemiliver.

Cell Seeding Technology for Microarray-Based Quantitative Human Primary Skeletal Muscle Cell Analysis.

Pipetting techniques play a crucial role in obtaining reproducible and reliable results, especially when seeding cells on small target areas, such as on microarrays, biochips or microfabricated cell culture systems. For very rare cells, such as human primary skeletal muscle cells (skMCs), manual (freehand) cell seeding techniques invariably result in nonuniform cell spreading and heterogeneous cell densities, giving rise to undesirable variations in myogenesis and differentiation. To prevent such technique-dependent variation, we have designed and fabricated a simple, low-cost pipet guidance device (PGD), and holder that works with hand-held pipettes. This work validates the accuracy and reproducibility of the PGD platform and compares its effectiveness with manual and robotic seeding techniques. The PGD system ensures reproducibility of cell seeding, comparable to that of more expensive robotic dispensing systems, resulting in a high degree of cell uniformity and homogeneous cell densities, while also enabling cell community studies. As compared to freehand pipetting, PGD-assisted seeding of C2C12 mouse myoblasts showed 5.3 times more myotube formation and likewise myotubes derived from PGD-seeded human primary skMCs were 3.6 times thicker and 2.2 times longer. These results show that this novel, yet simple PGD-assisted pipetting technique provides precise cell seeding on small targets, ensuring reproducible and reliable high-throughput cell assays.

DDS, 4,4'-diaminodiphenylsulfone, extends organismic lifespan.

DDS, 4,4'-diaminodiphenylsulfone, is the most common drug prescribed to treat Hansen disease patients. In addition to its antibacterial activity, DDS has been reported to be involved in other cellular processes that occur in eukaryotic cells. Because DDS treatment significantly enhances the antioxidant activity in humans, we examined its effect on lifespan extension. Here we show that DDS extends organismic lifespan using Caenorhabditis elegans as a model system. DDS treatment caused a delay in aging and decreased the levels of a mitochondrial complex. The oxygen consumption rate was also significantly lowered. Consistent with these data, paraquat treatment evoked less reactive oxygen species in DDS-treated worms, and these worms were less sensitive to paraquat. Interestingly enough, all of the molecular events caused by DDS treatment were consistently reproduced in mice treated with DDS for 3 mo and in the C2C12 muscle cell line. Structural prediction identified pyruvate kinase (PK) as a protein target of DDS. Indeed, DDS bound and inhibited PK in vitro and inhibited it in vivo, and a PK mutation conferred extended lifespan of C. elegans. Supplement of pyruvate to the media protected C2C12 cells from apoptosis caused by paraquat. Our findings establish the significance of DDS in lowering reactive oxygen species generation and extending the lifespan, which renders the rationale to examining the possible effect of DDS on human lifespan extension.

Exocrine pancreatic cancer as a second primary malignancy: A population-based study.

Backgrounds/Aims: Although cancer survivors are at higher risk of developing second primary malignancies, cancer surveillance strategies for them have not yet been established. This study aimed to identify first primary cancers that had high risks of developing second primary exocrine pancreatic cancer (EPC). Methods: Data on individuals diagnosed with primary cancers between 1993 and 2017 were obtained from the Korea Central Cancer Registry. The standardized incidence ratios (SIRs) of second primary EPCs were analyzed according to the primary tumor sites and follow-up periods. Results: Among the 3,205,840 eligible individuals, 4,836 (0.15%) had second primary EPCs, which accounted for 5.8% of the total EPC patients in Korea. Between 1 and 5 years after the diagnosis of first primary cancers, SIRs of second primary EPCs were increased in patients whose first primary cancers were in the bile duct (males 2.99; females 5.03) in both sexes, and in the small intestine (3.43), gallbladder (3.21), and breast (1.26) in females. Among those who survived 5 or more years after the diagnosis of first primary cancers, SIRs of second primary EPCs were elevated in patients whose first primary cancers were in the bile duct (males 2.61; females 2.33), gallbladder (males 2.29; females 2.22), and kidney (males 1.39; females 1.73) in both sexes, and ovary (1.66) and breast (1.38) in females. Conclusions: Survivors of first primary bile duct, gallbladder, kidney, ovary, and female breast cancer should be closely monitored for the occurrence of second primary EPCs, even after 5 years of follow-up.

Farnesol prevents aging-related muscle weakness in mice through enhanced farnesylation of Parkin-interacting substrate.

Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a master regulator of mitochondrial biogenesis. Reduced PGC-1α abundance is linked to skeletal muscle weakness in aging or pathological conditions, such as neurodegenerative diseases and diabetes; thus, elevating PGC-1α abundance might be a promising strategy to treat muscle aging. Here, we performed high-throughput screening and identified a natural compound, farnesol, as a potent inducer of PGC-1α. Farnesol administration enhanced oxidative muscle capacity and muscle strength, leading to metabolic rejuvenation in aged mice. Moreover, farnesol treatment accelerated the recovery of muscle injury associated with enhanced muscle stem cell function. The protein expression of Parkin-interacting substrate (PARIS/Zfp746), a transcriptional repressor of PGC-1α, was elevated in aged muscles, likely contributing to PGC-1α reduction. The beneficial effect of farnesol on aged muscle was mediated through enhanced PARIS farnesylation, thereby relieving PARIS-mediated PGC-1α suppression. Furthermore, short-term exercise increased PARIS farnesylation in the muscles of young and aged mice, whereas long-term exercise decreased PARIS expression in the muscles of aged mice, leading to the elevation of PGC-1α. Collectively, the current study demonstrated that the PARIS-PGC-1α pathway is linked to muscle aging and that farnesol treatment can restore muscle functionality in aged mice through increased farnesylation of PARIS.

Malondialdehyde inhibits an AMPK-mediated nuclear translocation and repression activity of ALDH2 in transcription.

Aging process results from deleterious damages by reactive oxygen species, in particular, various metabolic aldehydes. Aldehyde dehydrogenase 2 (ALDH2) is one of metabolic enzymes detoxifying various aldehydes under oxidative conditions. AMP-activated protein kinase (AMPK) plays a key role in controlling metabolic process. However, little was known about the relationship of ALDH2 with AMPK under oxidative conditions. Here, we, by using MDA-specific monoclonal antibody, screened the tissues of young and old rats for MDA-modified proteins and identified an ALDH2 as a prominent MDA-modified protein band in the old rat kidney tissue. ALDH2 associates with AMPK and is phosphorylated by AMPK. In addition, AICAR, an activator of AMP-activated protein kinase, induces the nuclear translocation of ALDH2. ALDH2 in nucleus is involved in general transcription repression by association with histone deacetylases. Furthermore, MDA modification inhibited the translocation of ALDH2 and the association with AMPK, and ultimately led to de-repression of transcription in the reporter system analysis. In this study, we have demonstrated that ALDH2 acts as a transcriptional repressor in response to AMPK activation, and MDA modifies ALDH2 and inhibits repressive activity of ALDH2 in general transcription. We thus suggest that increasing amount of MDA during aging process may interrupt the nuclear function of ALDH2, modulated by AMPK.

Incisional hernia after minimally invasive gastrectomy in gastric cancer patients.

Purpose: Although there are several studies on the incidence and risk factors for incisional hernia (IH) after open surgery, data about IH after minimally invasive surgery (MIS) for gastric cancer is rare. This study aimed to identify the incidence and risk factors for IH after MIS in gastric cancer patients. Methods: We analyzed the clinicopathologic data of patients who had laparoscopic or robotic gastric cancer surgeries between January 2006 and July 2019 at National Cancer Center, South Korea. Risk factors for development of IH were investigated with univariate and multivariate analyses. Results: A total of 2,769 patients underwent laparoscopic-assisted or robot-assisted gastrectomy with extracorporeal gastric resection and reconstruction, while 1,469 underwent totally laparoscopic or totally robotic gastrectomy (TLRG) with intracorporeal gastric resection and reconstruction. IH repair was performed in 23 patients (0.5%) after gastric cancer surgery. In the multivariate analysis, female sex (odds ratio [OR], 5.23; 95% confidence interval [CI], 2.03-13.43; p = 0.001), high body mass index (BMI) of ≥25 kg/m2 (OR, 4.23; 95% CI, 1.73-10.35; p = 0.002), larger tumor size (OR, 21.67; 95% CI, 5.37-87.34; p < 0.001), and intracorporeal procedure (OR, 5.63; 95% CI, 2.15-14.61; p < 0.001) were independent significant risk factors for IH. Conclusion: IH after MIS for gastric cancer is not common. Female sex, high BMI, large tumor size, and intracorporeal procedure were significant risk factors for it in this study. Therefore, in patients with risk factors, surgeons should cautiously close the abdominal wall access wound after MIS for gastric cancer, to prevent IH.

Effects of exercise-induced beta-hydroxybutyrate on muscle function and cognitive function.

Recent studies have shown that exercise improves skeletal muscle and cognitive function by stimulating the secretion of numerous molecules. In particular, previous studies have suggested that exercise-induced beta-hydroxybutyrate (BHB) release might improve skeletal muscle and cognitive function, but to date these studies have been limited to cell and animal models. Therefore, we aimed to determine how an exercise-induced increase in BHB affects skeletal muscle and cognitive function at a cellular level, in an animal model, and in humans. The effects of BHB on skeletal muscle and cognitive function were determined by treating C2C12 and C6 cell lines with BHB, and by measuring the skeletal muscle and serum BHB concentrations in aged mice after endurance or resistance exercise. In addition, serum BHB concentration was measured before and after high-speed band exercise in elderly people, and its relationships with muscle and cognitive function were analyzed. We found that BHB increased cell viability and brain-derived neurotrophic factor expression level in C6 cells, and endurance exercise, but not resistance exercise, increased the muscle BHB concentration in aged mice. Furthermore, the BHB concentration was positively related to skeletal muscle and cognitive function. Exercise did not increase the serum BHB concentration in the elderly people and BHB did not correlate with cognitive function, but after excluding the five people with the highest preexisting serum concentrations of BHB, the BHB concentrations of the remaining participants were increased by exercise, and the concentration showed a tendency toward a positive correlation with cognitive function. Thus, the BHB released by skeletal muscle following endurance exercise may improve muscle and cognitive function in animals and humans.

Disruption of nucleocytoplasmic trafficking as a cellular senescence driver.

Senescent cells exhibit a reduced response to intrinsic and extrinsic stimuli. This diminished reaction may be explained by the disrupted transmission of nuclear signals. However, this hypothesis requires more evidence before it can be accepted as a mechanism of cellular senescence. A proteomic analysis of the cytoplasmic and nuclear fractions obtained from young and senescent cells revealed disruption of nucleocytoplasmic trafficking (NCT) as an essential feature of replicative senescence (RS) at the global level. Blocking NCT either chemically or genetically induced the acquisition of an RS-like senescence phenotype, named nuclear barrier-induced senescence (NBIS). A transcriptome analysis revealed that, among various types of cellular senescence, NBIS exhibited a gene expression pattern most similar to that of RS. Core proteomic and transcriptomic patterns common to both RS and NBIS included upregulation of the endocytosis-lysosome network and downregulation of NCT in senescent cells, patterns also observed in an aging yeast model. These results imply coordinated aging-dependent reduction in the transmission of extrinsic signals to the nucleus and in the nucleus-to-cytoplasm supply of proteins/RNAs. We further showed that the aging-associated decrease in Sp1 transcription factor expression was critical for the downregulation of NCT. Our results suggest that NBIS is a modality of cellular senescence that may represent the nature of physiological aging in eukaryotes.

Satellite cell-specific ablation of Cdon impairs integrin activation, FGF signalling, and muscle regeneration.

BACKGROUND: Perturbation in cell adhesion and growth factor signalling in satellite cells results in decreased muscle regenerative capacity. Cdon (also called Cdo) is a component of cell adhesion complexes implicated in myogenic differentiation, but its role in muscle regeneration remains to be determined. METHODS: We generated inducible satellite cell-specific Cdon ablation in mice by utilizing a conditional Cdon allele and Pax7 CreERT2 . To induce Cdon ablation, mice were intraperitoneally injected with tamoxifen (tmx). Using cardiotoxin-induced muscle injury, the effect of Cdon depletion on satellite cell function was examined by histochemistry, immunostaining, and 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay. Isolated myofibers or myoblasts were utilized to determine stem cell function and senescence. To determine pathways related to Cdon deletion, injured muscles were subjected to RNA sequencing analysis. RESULTS: Satellite cell-specific Cdon ablation causes impaired muscle regeneration with fibrosis, likely attributable to decreased proliferation, and senescence, of satellite cells. Cultured Cdon-depleted myofibers exhibited 32 ± 9.6% of EdU-positive satellite cells compared with 58 ± 4.4% satellite cells in control myofibers (P < 0.05). About 32.5 ± 3.7% Cdon-ablated myoblasts were positive for senescence-associated ß-galactosidase (SA-ß-gal) while only 3.6 ± 0.5% of control satellite cells were positive (P < 0.001). Transcriptome analysis of muscles at post-injury Day 4 revealed alterations in genes related to mitogen-activated protein kinase signalling (P < 8.29 e-5 ) and extracellular matrix (P < 2.65 e-24 ). Consistent with this, Cdon-depleted tibialis anterior muscles had reduced phosphorylated extracellular signal-regulated kinase (p-ERK) protein levels and expression of ERK targets, such as Fos (0.23-fold) and Egr1 (0.31-fold), relative to mock-treated control muscles (P < 0.001). Cdon-depleted myoblasts exhibited impaired ERK activation in response to basic fibroblast growth factor. Cdon ablation resulted in decreased and/or mislocalized integrin ß1 activation in satellite cells (weak or mislocalized integrin1 in tmx = 38.7 ± 1.9%, mock = 21.5 ± 6%, P < 0.05), previously linked with reduced fibroblast growth factor (FGF) responsiveness in aged satellite cells. In mechanistic studies, Cdon interacted with and regulated cell surface localization of FGFR1 and FGFR4, likely contributing to FGF responsiveness of satellite cells. Satellite cells from a progeria model, Zmpste24-/- myofibers, showed decreased Cdon levels (Cdon-positive cells in Zmpste24-/- = 63.3 ± 11%, wild type = 90 ± 7.7%, P < 0.05) and integrin ß1 activation (weak or mislocalized integrin ß1 in Zmpste24-/- = 64 ± 6.9%, wild type = 17.4 ± 5.9%, P < 0.01). CONCLUSIONS: Cdon deficiency in satellite cells causes impaired proliferation of satellite cells and muscle regeneration via aberrant integrin and FGFR signalling.

ZNF746/PARIS overexpression induces cellular senescence through FoxO1/p21 axis activation in myoblasts.

Various stresses, including oxidative stress, impair the proliferative capacity of muscle stem cells leading to declined muscle regeneration related to aging or muscle diseases. ZNF746 (PARIS) is originally identified as a substrate of E3 ligase Parkin and its accumulation is associated with Parkinson's disease. In this study, we investigated the role of PARIS in myoblast function. PARIS is expressed in myoblasts and decreased during differentiation. PARIS overexpression decreased both proliferation and differentiation of myoblasts without inducing cell death, whereas PARIS depletion enhanced myoblast differentiation. Interestingly, high levels of PARIS in myoblasts or fibroblasts induced cellular senescence with alterations in gene expression associated with p53 signaling, inflammation, and response to oxidative stress. PARIS overexpression in myoblasts starkly enhanced oxidative stress and the treatment of an antioxidant Trolox attenuated the impaired proliferation caused by PARIS overexpression. FoxO1 and p53 proteins are elevated in PARIS-overexpressing cells leading to p21 induction and the depletion of FoxO1 or p53 reduced p21 levels induced by PARIS overexpression. Furthermore, both PARIS and FoxO1 were recruited to p21 promoter region and Trolox treatment attenuated FoxO1 recruitment. Taken together, PARIS upregulation causes oxidative stress-related FoxO1 and p53 activation leading to p21 induction and cellular senescence of myoblasts.

Indoprofen prevents muscle wasting in aged mice through activation of PDK1/AKT pathway.

BACKGROUND: Muscle wasting, resulting from aging or pathological conditions, leads to reduced quality of life, increased morbidity, and increased mortality. Much research effort has been focused on the development of exercise mimetics to prevent muscle atrophy and weakness. In this study, we identified indoprofen from a screen for peroxisome proliferator-activated receptor γ coactivator α (PGC-1α) inducers and report its potential as a drug for muscle wasting. METHODS: The effects of indoprofen treatment on dexamethasone-induced atrophy in mice and in 3-phosphoinositide-dependent protein kinase-1 (PDK1)-deleted C2C12 myotubes were evaluated by immunoblotting to determine the expression levels of myosin heavy chain and anabolic-related and oxidative metabolism-related proteins. Young, old, and disuse-induced muscle atrophic mice were administered indoprofen (2 mg/kg body weight) by gavage. Body weight, muscle weight, grip strength, isometric force, and muscle histology were assessed. The expression levels of muscle mass-related and function-related proteins were analysed by immunoblotting or immunostaining. RESULTS: In young (3-month-old) and aged (22-month-old) mice, indoprofen treatment activated oxidative metabolism-related enzymes and led to increased muscle mass. Mechanistic analysis using animal models and muscle cells revealed that indoprofen treatment induced the sequential activation of AKT/p70S6 kinase (S6K) and AMP-activated protein kinase (AMPK), which in turn can augment protein synthesis and PGC-1α induction, respectively. Structural prediction analysis identified PDK1 as a target of indoprofen and, indeed, short-term treatment with indoprofen activated the PDK1/AKT/S6K pathway in muscle cells. Consistent with this finding, PDK1 inhibition abrogated indoprofen-induced AKT/S6K activation and hypertrophic response. CONCLUSIONS: Our findings demonstrate the effects of indoprofen in boosting skeletal muscle mass through the sequential activation of PDK1/AKT/S6K and AMPK/PGC-1α. Taken together, our results suggest that indoprofen represents a potential drug to prevent muscle wasting and weakness related to aging or muscle diseases.

Alterations of epinephrine-induced gluconeogenesis in aging.

The effects of glucagon and epinephrine on gluconeogenesis in young (4 month) and old (24 month) Fisher 344 rat hepatocytes were compared. In contrast to glucagon, which had a similar effect on gluconeogenesis in both young and old cells, epinephrine caused a smaller increase in gluconeogenesis in old rat hepatocytes than in young hepatocytes. beta2 adrenergic receptor (beta2-AR) expression slightly decreased in aged rat liver, and there were differences between young and old hepatocytes in their patterns of G protein coupled receptor kinases, which are involved in the activation of beta2-AR receptor signal desensitization. The major isoform of the kinase changed from GRK2 to GRK3 and the expression of beta-arrestin, which is recruited by the phosphorylated beta2-AR for internalization and degradation, increased in aged rat liver. GRK3 overexpression also decreased the glucose output from young rat hepatocytes. We conclude that an age-associated reduction in epinephrine-induced gluconeogenesis occurs through the epinephrine receptor desensitizing system.

Skeletal muscle-specific Prmt1 deletion causes muscle atrophy via deregulation of the PRMT6-FOXO3 axis.

Protein arginine methyltransferases (PRMTs) have emerged as important regulators of skeletal muscle metabolism and regeneration. However, the direct roles of the various PRMTs during skeletal muscle remodeling remain unclear. Using skeletal muscle-specific prmt1 knockout mice, we examined the function and downstream targets of PRMT1 in muscle homeostasis. We found that muscle-specific PRMT1 deficiency led to muscle atrophy. PRMT1-deficient muscles exhibited enhanced expression of a macroautophagic/autophagic marker LC3-II, FOXO3 and muscle-specific ubiquitin ligases, TRIM63/MURF-1 and FBXO32, likely contributing to muscle atrophy. The mechanistic study reveals that PRMT1 regulates FOXO3 through PRMT6 modulation. In the absence of PRMT1, increased PRMT6 specifically methylates FOXO3 at arginine 188 and 249, leading to its activation. Finally, we demonstrate that PRMT1 deficiency triggers FOXO3 hyperactivation, which is abrogated by PRMT6 depletion. Taken together, PRMT1 is a key regulator for the PRMT6-FOXO3 axis in the control of autophagy and protein degradation underlying muscle maintenance. Abbreviations: Ad-RNAi: adenovirus-delivered small interfering RNA; AKT: thymoma viral proto-oncogene; AMPK: AMP-activated protein kinase; Baf A1: bafilomycin A1; CSA: cross-sectional area; EDL: extensor digitorum longus; FBXO32: F-box protein 32; FOXO: forkhead box O; GAS: gatrocnemieus; HDAC: histone deacetylase; IGF: insulin-like growth factor; LAMP: lysosomal-associated membrane protein; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; mKO: Mice with skeletal muscle-specific deletion of Prmt1; MTOR: mechanistic target of rapamycin kinase; MYH: myosin heavy chain; MYL1/MLC1f: myosin, light polypeptide 1; PRMT: protein arginine N-methyltransferase; sgRNA: single guide RNA; SQSTM1: sequestosome 1; SOL: soleus; TA: tibialis anterior; TRIM63/MURF-1: tripartite motif-containing 63; YY1: YY1 transcription factor.

DDS promotes longevity through a microbiome-mediated starvation signal.

The antibiotic diaminodiphenyl sulfone (DDS) is used in combination with other antibiotics as a first line treatment for leprosy. DDS has been previously reported to extend lifespan in Caenorhabditis elegans through inhibition of pyruvate kinase and decreased mitochondrial function. Here we report an alternative mechanism of action by which DDS promotes longevity in C. elegans by reducing folate production by the microbiome. This results in altered methionine cycle metabolite levels mimicking the effects of metformin and lifespan extension that is dependent on the starvation- and hypoxia-induced flavin containing monoxygenase, FMO-2.

Lysophosphatidic acid and adenylyl cyclase inhibitor increase proliferation of senescent human diploid fibroblasts by inhibiting adenosine monophosphate-activated protein kinase.

This study was designed to elucidate the molecular mechanism underlying lysophosphatidic acid (LPA) and adenylyl cyclase inhibitor SQ22536 (ACI)-induced senescent human diploid fibroblast (HDF) proliferation. Because adenosine monophosphate (AMP)-activated protein kinase (AMPK) is known to inhibit cell proliferation, we examined the phosphorylation status of AMPK and p53 and the expression level of p21(waf1/cip1) after treating HDFs with LPA and ACI. Phosphorylation of AMPKalpha on threonine-172 (p-Thr172-AMPKalpha) increases its catalytic activity but phosphorylation on serine-485/491 (p-Ser485/491-AMPKalpha) reduces the accessibility of the Thr172 phosphorylation site thereby inhibiting its catalytic activity. LPA increased p-Ser485/491-AMPKalpha, presumably by activating cAMP-dependent protein kinase (PKA). However, ACI reduced p-Thr172-AMPKalpha by inhibiting the LKB signaling. Our data demonstrated that both LPA and ACI inhibit the catalytic activity of AMPKalpha and p53 by differentially regulating phosphorylation of AMPKalpha, causing increased senescent cell proliferation. These findings suggest that the proliferation potential of senescent HDFs can be modulated through the regulation of the AMPK signaling pathway.