Publications
Circulating microRNA profile in humans and mice with congenital GH deficiency
Tatiana D Saccon, Augusto Schneider, Cindi G Marinho, Allancer D C Nunes, Sarah Noureddine, Joseph Dhahbi, Yury O Nunez Lopez, Gage LeMunyan, Roberto Salvatori, Carla R P Oliveira, Alécia A Oliveira-Santos, Nicolas Musi, Andrzej Bartke, Manuel H Aguiar-Oliveira, Michal M Masternak
Aging Cell. 2021 Jul;20(7):e13420. doi: 10.1111/acel.13420. Epub 2021 Jun 12.
Abstract:
Reduced inflammation, increased insulin sensitivity, and protection against cancer are shared between humans and mice with GH/IGF1 deficiency. Beyond hormone levels, miRNAs are important regulators of metabolic changes associated with healthy aging. We hypothesized that GH deficiency in humans alters the abundance of circulating miRNAs and that a subset of those miRNAs may overlap with those found in GH-deficient mice. In this study, subjects with untreated congenital isolated GH deficiency (IGHD; n = 23) and control subjects matched by age and sex (n = 23) were recruited and serum was collected for miRNA sequencing. Serum miRNAs from young (6 month) and old (22 month) Ames dwarf (df/df) mice with GH deficiency and their WT littermates (n = 5/age/genotype group) were used for comparison. We observed 14 miRNAs regulated with a genotype by age effect and 19 miRNAs regulated with a genotype effect independent of age in serum of IGHD subjects. These regulated miRNAs are known for targeting pathways associated with longevity such as mTOR, insulin signaling, and FoxO. The aging function was overrepresented in IGHD individuals, mediated by hsa-miR-31, hsa-miR-146b, hsa-miR-30e, hsa-miR-100, hsa-miR-181b-2, hsa-miR-195, and hsa-miR-181b-1, which target the FoxO and mTOR pathways. Intriguingly, miR-181b-5p, miR-361-3p, miR-144-3p, and miR-155-5p were commonly regulated in the serum of humans and GH-deficient mice. In vitro assays confirmed target genes for the main up-regulated miRNAs, suggesting miRNAs regulated in IGHD individuals can regulate the expression of age-related genes. These findings indicate that systemic miRNAs regulated in IGHD individuals target pathways involved in aging in both humans and mice.
Keywords: Ames dwarf; IGHD; dwarfism; miRNA.
Chloride channel accessory 1 integrates chloride channel activity and mTORC1 in aging-related kidney injury
Hak Joo Lee, Andrew Donati, Denis Feliers, Yuyang Sun, Yanli Ding, Muniswamy Madesh, Adam B Salmon, Yuji Ikeno, Corinna Ross, Christopher L O’Connor, Wenjun Ju, Markus Bitzer, Yidong Chen, Goutam Ghosh Choudhury, Brij B Singh, Kumar Sharma, Balakuntalam S Kasinath
Aging Cell. 2021 Jul;20(7):e13407. doi: 10.1111/acel.13407. Epub 2021 Jun 12.
Abstract:
The mechanism of kidney injury in aging are not well understood. In order to identify hitherto unknown pathways of aging-related kidney injury, we performed RNA-Seq on kidney extracts of young and aged mice. Expression of chloride (Cl) channel accessory 1 (CLCA1) mRNA and protein was increased in the kidneys of aged mice. Immunostaining showed a marked increase in CLCLA1 expression in the proximal tubules of the kidney from aged mice. Increased kidney CLCA1 gene expression also correlated with aging in marmosets and in a human cohort. In aging mice, increased renal cortical CLCA1 content was associated with hydrogen sulfide (H2 S) deficiency, which was ameliorated by administering sodium hydrosulfide (NaHS), a source of H2 S. In order to study whether increased CLCA1 expression leads to injury phenotype and the mechanisms involved, stable transfection of proximal tubule epithelial cells overexpressing human CLCA1 (hCLCA1) was performed. Overexpression of hCLCA1 augmented Cl- current via the Ca++ -dependent Cl- channel TMEM16A (anoctamin-1) by patch-clamp studies. hCLCA1 overexpression also increased the expression of fibronectin, a matrix protein, and induced the senescence-associated secretory phenotype (SASP). Mechanistic studies underlying these changes showed that hCLCA1 overexpression leads to inhibition of AMPK activity and stimulation of mTORC1 as cellular signaling determinants of injury. Both TMEM16A inhibitor and NaHS reversed these signaling events and prevented changes in fibronectin and SASP. We conclude that CLCA1-TMEM16A-Cl- current pathway is a novel mediator of kidney injury in aging that is regulated by endogenous H2 S.
Keywords: fibrosis; ion transport; senescence-associated secretory phenotype.
Phospholipids of APOE lipoproteins activate microglia in an isoform-specific manner in preclinical models of Alzheimer’s disease
Nicholas F Fitz, Kyong Nyon Nam, Cody M Wolfe, Florent Letronne, Brittany E Playso, Bistra E Iordanova, Takashi D Y Kozai, Richard J Biedrzycki, Valerian E Kagan, Yulia Y Tyurina, Xianlin Han, Iliya Lefterov, Radosveta Koldamova
Nat Commun. 2021 Jun 7;12(1):3416. doi: 10.1038/s41467-021-23762-0.
Abstract:
APOE and Trem2 are major genetic risk factors for Alzheimer’s disease (AD), but how they affect microglia response to Aβ remains unclear. Here we report an APOE isoform-specific phospholipid signature with correlation between human APOEε3/3 and APOEε4/4 AD brain and lipoproteins from astrocyte conditioned media of APOE3 and APOE4 mice. Using preclinical AD mouse models, we show that APOE3 lipoproteins, unlike APOE4, induce faster microglial migration towards injected Aβ, facilitate Aβ uptake, and ameliorate Aβ effects on cognition. Bulk and single-cell RNA-seq demonstrate that, compared to APOE4, cortical infusion of APOE3 lipoproteins upregulates a higher proportion of genes linked to an activated microglia response, and this trend is augmented by TREM2 deficiency. In vitro, lack of TREM2 decreases Aβ uptake by APOE4-treated microglia only, suggesting TREM2-APOE interaction. Our study elucidates phenotypic and transcriptional differences in microglial response to Aβ mediated by APOE3 or APOE4 lipoproteins in preclinical models of AD.
Age and sex modify cellular proliferation responses to oxidative stress and glucocorticoid challenges in baboon cells
Daniel A Adekunbi, Cun Li, Peter W Nathanielsz, Adam B Salmon
Geroscience. 2021 Aug;43(4):2067-2085. doi: 10.1007/s11357-021-00395-1. Epub 2021 Jun 5.
Abstract:
Aging is associated with progressive loss of cellular homeostasis resulting from intrinsic and extrinsic challenges. Lack of a carefully designed, well-characterized, precise, translational experimental model is a major limitation to understanding the cellular perturbations that characterize aging. Here, we tested the feasibility of primary fibroblasts isolated from nonhuman primates (baboons) as a model of cellular resilience in response to homeostatic challenge. Using a real-time live-cell imaging system, we precisely defined a protocol for testing effects of prooxidant compounds (e.g., hydrogen peroxide (H2O2), paraquat), thapsigargin, dexamethasone, and a low glucose environment on cell proliferation in fibroblasts derived from baboons across the life course (n = 11/sex). Linear regression analysis indicated that donor age significantly reduced the ability of cells to proliferate following exposure to H2O2 (50 and 100 µM) and paraquat (100 and 200 µM) challenges in cells from males (6.4-21.3 years; average lifespan 21 years) but not cells from females (4.3-15.9 years). Inhibitory effects of thapsigargin on cell proliferation were dependent on challenge duration (2 vs 24 h) and concentration (0.1 and 1 µM). Cells from older females (14.4-15.9 years) exhibited greater resilience to thapsigargin (1 µM; 24 h) and dexamethasone (500 µM) challenges than did those from younger females (4.3-6.7 years). The cell proliferation response to low glucose (1 mM) was reduced with age in both sexes. These data indicate that donor’s chronological age and sex are important variables in determining fibroblast responses to metabolite and other challenges.
Keywords: Aging; Baboon; Cell proliferation; Fibroblast; Oxidative stress; Resilience.
Beta-guanidinopropionic acid does not extend Drosophila lifespan
Jonathan D Dorigatti, Kevin M Thyne, Brett C Ginsburg, Adam B Salmon
Biochem Biophys Rep. 2021 Jun 3:27:101040. doi: 10.1016/j.bbrep.2021.101040. eCollection 2021 Sep.
Abstract:
Activation of AMP activated protein kinase (AMPK) signaling has been demonstrated to extend lifespan and improve healthspan across multiple species. This suggests pharmaceutical approaches to increase AMPK hold the potential to modify the aging process and promote healthy aging. Beta-guanidinopropionic acid (GPA) is a naturally occurring metabolite structurally similar to creatine. GPA is capable of activating AMPK signaling in mammalian models via competitive inhibition of cytosolic creatine kinase. A previous report suggested that dietary GPA supplementation increased lifespan in Drosophila through its effect on AMPK signaling and regulation of autophagy. However, studies in Caenorhabditis have found no beneficial effect of this compound on worm lifespan and that GPA may actually diminish lifespan in at least one Caenorhabditis species. To confirm previous reports of increased longevity in Drosophila, we tested a wide range of GPA concentrations on lifespan and healthspan in both male and female W1118 flies. We report here that GPA does not extend lifespan in Drosophila as previously reported. Moreover, high doses of GPA are detrimental to Drosophila lifespan and stress resistance in male flies. These results suggest the lack of a robust effect of GPA on Drosophila lifespan and highlight the importance of replication studies within the field of aging.
Keywords: Beta-guanidinopropionic acid; Biology of aging; Drosophila; Lifespan extension; Stress resistance.
β2-Adrenergic receptor agonist induced hepatic steatosis in mice: modeling nonalcoholic fatty liver disease in hyperadrenergic states
Yun Shi, Jason Pizzini, Hanzhou Wang, Falguni Das, Parveez Ahamed Abdul Azees, Goutam Ghosh Choudhury, Jeffrey L Barnes, Mengwei Zang, Susan T Weintraub, Chih-Ko Yeh, Michael S Katz, Amrita Kamat
Am J Physiol Endocrinol Metab. 2021 Jul 1;321(1):E90-E104. doi: 10.1152/ajpendo.00651.2020. Epub 2021 May 24.
Abstract:
Nonalcoholic fatty liver disease (NAFLD) is a spectrum of disorders ranging from hepatic steatosis [excessive accumulation of triglycerides (TG)] to nonalcoholic steatohepatitis, which can progress to cirrhosis and hepatocellular carcinoma. The molecular pathogenesis of steatosis and progression to more severe NAFLD remains unclear. Obesity and aging, two principal risk factors for NAFLD, are associated with a hyperadrenergic state. β-Adrenergic responsiveness in liver increases in animal models of obesity and aging, and in both is linked to increased hepatic expression of β2-adrenergic receptors (β2-ARs). We previously showed that in aging rodents intracellular signaling from elevated hepatic levels of β2-ARs may contribute to liver steatosis. In this study we demonstrate that injection of formoterol, a highly selective β2-AR agonist, to mice acutely results in hepatic TG accumulation. Further, we have sought to define the intrahepatic mechanisms underlying β2-AR mediated steatosis by investigating changes in hepatic expression and cellular localization of enzymes, transcription factors, and coactivators involved in processes of lipid accrual and disposition-and also functional aspects thereof-in livers of formoterol-treated animals. Our results suggest that β2-AR activation by formoterol leads to increased hepatic TG synthesis and de novo lipogenesis, increased but incomplete β-oxidation of fatty acids with accumulation of potentially toxic long-chain acylcarnitine intermediates, and reduced TG secretion-all previously invoked as contributors to fatty liver disease. Experiments are ongoing to determine whether sustained activation of hepatic β2-AR signaling by formoterol might be utilized to model fatty liver changes occurring in hyperadrenergic states of obesity and aging, and thereby identify novel molecular targets for the prevention or treatment of NAFLD. NEW & NOTEWORTHY Results of our study suggest that β2-adrenergic receptor (β2-AR) activation by agonist formoterol leads to increased hepatic TG synthesis and de novo lipogenesis, incomplete β-oxidation of fatty acids with accumulation of long-chain acylcarnitine intermediates, and reduced TG secretion. These findings may, for the first time, implicate a role for β2-AR responsive dysregulation of hepatic lipid metabolism in the pathogenetic processes underlying NAFLD in hyperadrenergic states such as obesity and aging.
Keywords: aging; lipogenesis; liver; obesity; triglycerides.
Beta-guanidinopropionic acid has age-specific effects on markers of health and function in mice
Jonathan D Dorigatti, Kevin M Thyne, Brett C Ginsburg, Adam B Salmon
Geroscience. 2021 Jun;43(3):1497-1511. doi: 10.1007/s11357-021-00372-8. Epub 2021 Apr 23.
Abstract:
AMP-activated protein kinase (AMPK) is a central regulator of both lifespan and health across multiple model organisms. β-Guanidinopropionic acid (GPA) is an endogenous AMPK activator previously shown to improve metabolic function in young and obese mice. In this study, we tested whether age of administration significantly affects the physiological outcomes of GPA administration in mice. We report that intervention starting at 7-8 months (young) results in activation of AMPK signaling and a phenotype consisting of lower body mass, improved glucose control, enhanced exercise tolerance, and altered mitochondrial electron transport chain flux similar to previous reports. When GPA treatment is started at 18-19 months (old), the effect of GPA on AMPK signaling is blunted compared to younger mice despite similar accumulation of GPA in skeletal muscle. Even so, GPA administration in older animals delayed age-related declines in lean mass, improved measures of gait performance and circadian rhythm, and increased fat metabolism as measured by respiratory exchange ratio. These results are likely partially driven by the relative difference in basal function and metabolic plasticity between young and old mice. Our results suggest that age-related declines in AMPK sensitivity may limit potential strategies targeting AMPK signaling in older subjects and suggest that further research and development is required for AMPK activators to realize their full potential.
Keywords: AMPK; Aging; Beta-guanidinopropionic acid; Healthspan.
mTOR Attenuation with Rapamycin Reverses Neurovascular Uncoupling and Memory Deficits in Mice Modeling Alzheimer’s Disease
Candice E Van Skike, Stacy A Hussong, Stephen F Hernandez, Andy Q Banh, Nicholas DeRosa, Veronica Galvan
J Neurosci. 2021 May 12;41(19):4305-4320. doi: 10.1523/JNEUROSCI.2144-20.2021. Epub 2021 Apr 22.
Abstract:
Vascular dysfunction is a universal feature of aging and decreased cerebral blood flow has been identified as an early event in the pathogenesis of Alzheimer’s disease (AD). Cerebrovascular dysfunction in AD includes deficits in neurovascular coupling (NVC), a mechanism that ensures rapid delivery of energy substrates to active neurons through the blood supply. The mechanisms underlying NVC impairment in AD, however, are not well understood. We have previously shown that mechanistic/mammalian target of rapamycin (mTOR) drives cerebrovascular dysfunction in models of AD by reducing the activity of endothelial nitric oxide synthase (eNOS), and that attenuation of mTOR activity with rapamycin is sufficient to restore eNOS-dependent cerebrovascular function. Here we show mTOR drives NVC impairments in an AD model through the inhibition of neuronal NOS (nNOS)- and non-NOS-dependent components of NVC, and that mTOR attenuation with rapamycin is sufficient to restore NVC and even enhance it above WT responses. Restoration of NVC and concomitant reduction of cortical amyloid-β levels effectively treated memory deficits in 12-month-old hAPP(J20) mice. These data indicate that mTOR is a critical driver of NVC dysfunction and underlies cognitive impairment in an AD model. Together with our previous findings, the present studies suggest that mTOR promotes cerebrovascular dysfunction in AD, which is associated with early disruption of nNOS activation, through its broad negative impact on nNOS as well as on non-NOS components of NVC. Our studies highlight the potential of mTOR attenuation as an efficacious treatment for AD and potentially other neurologic diseases of aging.SIGNIFICANCE STATEMENT Failure of the blood flow response to neuronal activation [neurovascular coupling (NVC)] in a model of AD precedes the onset of AD-like cognitive symptoms and is driven, to a large extent, by mammalian/mechanistic target of rapamycin (mTOR)-dependent inhibition of nitric oxide synthase activity. Our studies show that mTOR also drives AD-like failure of non-nitric oxide (NO)-mediated components of NVC. Thus, mTOR attenuation may serve to treat AD, where we find that neuronal NO synthase is profoundly reduced early in disease progression, and potentially other neurologic diseases of aging with cerebrovascular dysfunction as part of their etiology.
Keywords: Alzheimer’s disease; cerebral blood flow; cerebrovascular dysfunction; mTOR; nNOS; neurovascular coupling.
17-a-estradiol late in life extends lifespan in aging UM-HET3 male mice; nicotinamide riboside and three other drugs do not affect lifespan in either sex
David E Harrison, Randy Strong, Peter Reifsnyder, Navasuja Kumar, Elizabeth Fernandez, Kevin Flurkey, Martin A Javors, Marisa Lopez-Cruzan, Francesca Macchiarini, James F Nelson, Adrian Markewych, Alessandro Bitto, Amy L Sindler, Gino Cortopassi, Kylie Kavanagh, Lin Leng, Richard Bucala, Nadia Rosenthal, Adam Salmon, Timothy M Stearns, Molly Bogue, Richard A Miller
Aging Cell. 2021 May;20(5):e13328. doi: 10.1111/acel.13328. Epub 2021 Mar 31.
Abstract:
In genetically heterogeneous mice produced by the CByB6F1 x C3D2F1 cross, the “non-feminizing” estrogen, 17-α-estradiol (17aE2), extended median male lifespan by 19% (p < 0.0001, log-rank test) and 11% (p = 0.007) when fed at 14.4 ppm starting at 16 and 20 months, respectively. 90th percentile lifespans were extended 7% (p = 0.004, Wang-Allison test) and 5% (p = 0.17). Body weights were reduced about 20% after starting the 17aE2 diets. Four other interventions were tested in males and females: nicotinamide riboside, candesartan cilexetil, geranylgeranylacetone, and MIF098. Despite some data suggesting that nicotinamide riboside would be effective, neither it nor the other three increased lifespans significantly at the doses tested. The 17aE2 results confirm and extend our original reports, with very similar results when started at 16 months compared with mice started at 10 months of age in a prior study. The consistently large lifespan benefit in males, even when treatment is started late in life, may provide information on sex-specific aspects of aging.
Keywords: 17-α-estradiol; candesartan cilexetil; geranylgeranylacetone; heterogeneous mice; lifespan; macrophage migration inhibitory factor; nicotinamide riboside.
MnSOD Lysine 68 acetylation leads to cisplatin and doxorubicin resistance due to aberrant mitochondrial metabolism
Yucheng Gao, Yueming Zhu, Elizabeth L Tran, Valerie Tokars, Angela E Dean, Songhua Quan, David Gius
Int J Biol Sci. 2021 Mar 19;17(5):1203-1216. doi: 10.7150/ijbs.51184. eCollection 2021.
Abstract:
Manganese superoxide dismutase (MnSOD) acetylation (Ac) has been shown to be a key post-translational modification important in the regulation of detoxification activity in various disease models. We have previously demonstrated that MnSOD lysine-68 (K68) acetylation (K68-Ac) leads to a change in function from a superoxide-scavenging homotetramer to a peroxidase-directed monomer. Here, we found that estrogen receptor positive (ER+) breast cancer cell lines (MCF7 and T47D), selected for continuous growth in cisplatin (CDDP) and doxorubicin (DXR), exhibited an increase in MnSOD-K68-Ac. In addition, MnSOD-K68-Ac, as modeled by the expression of a validated acetylation mimic mutant gene (MnSODK68Q ), also led to therapy resistance to CDDP and DXR, altered mitochondrial structure and morphology, and aberrant cellular metabolism. MnSODK68Q expression in mouse embryo fibroblasts (MEFs) induced an in vitro transformation permissive phenotype. Computerized molecular protein dynamics analysis of both MnSOD-K68-Ac and MnSOD-K68Q exhibited a significant change in charge distribution along the α1 and α2 helices, directly adjacent to the Mn2+ binding site, implying that this decrease in surface charge destabilizes tetrameric MnSOD, leading to an enrichment of the monomer. Finally, monomeric MnSOD, as modeled by amber codon substitution to generate MnSOD-K68-Ac or MnSOD-K68Q expression in mammalian cells, appeared to incorporate Fe to maximally induce its peroxidase activity. In summary, these findings may explain the mechanism behind the observed structural and functional change of MnSOD-K68-Ac.
Keywords: MnSOD; SIRT3; SOD2; Sirtuins; acetylation; acetylome; aging; carcinogenesis; lysine 68; metabolism; mitochondria; signaling.