AKT1
RAC-alpha serine/threonine-protein kinase (EC 2.7.11.1) (Protein kinase B) (PKB) (Protein kinase B alpha) (PKB alpha) (Proto-oncogene c-Akt) (RAC-PK-alpha) [PKB] [RAC]
Publications[править]
Sustained macroautophagy/autophagy favors the differentiation of fibroblasts into myofibroblasts. Cellular senescence, another means of responding to long-term cellular stress, has also been linked to myofibroblast differentiation and fibrosis. Here, we evaluate the relationship between senescence and myofibroblast differentiation in the context of sustained autophagy. We analyzed markers of cell cycle arrest/senescence in fibroblasts [i]in vitro[/i], where autophagy was triggered by serum starvation (SS). Autophagic fibroblasts expressed the senescence biomarkers CDKN1A/p21 and CDKN2A/p16 and exhibited increased senescence-associated GLB1/beta-galactosidase activity. Inhibition of autophagy in serum-starved fibroblasts with 3-methyladenine, LY294002, or [i]ATG7[/i] (autophagy related 7) silencing prevented the expression of senescence-associated markers. Similarly, suppressing MTORC2 activation using rapamycin or by silencing [i]RICTOR[/i] also prevented senescence hallmarks. Immunofluorescence microscopy showed that senescence and myofibroblast differentiation were induced in different cells, suggesting mutually exclusive activation of senescence and myofibroblast differentiation. Reactive oxygen species (ROS) are known inducers of senescence and exposing fibroblasts to ROS scavengers decreased ROS production during SS, inhibited autophagy, and significantly reduced the expression of senescence and myofibroblast differentiation markers. ROS scavengers also curbed the AKT1 phosphorylation at Ser473, an MTORC2 target, establishing the importance of ROS in fueling MTORC2 activation. Inhibition of senescence by shRNA to [i]TP53[/i]/[i]p53[/i] and shRNA [i]CDKN2A[/i]/[i]p16[/i] increased myofibroblast differentiation, suggesting a negative feedback loop of senescence on autophagy-induced myofibroblast differentiation. Collectively, our results identify ROS as central inducers of MTORC2 activation during chronic autophagy, which in turn fuels senescence activation and myofibroblast differentiation in distinct cellular subpopulations. : 3-MA: 3-methyladenine; ACTA2: actin, alpha 2, smooth muscle, aorta; AKT1: AKT serine/threonine kinase 1; p-AKT1: AKT1 Ser473 phosphorylation; t-AKT1: total AKT serine/threonine kinase 1; ATG4A: autophagy related 4A cysteine peptidase; ATG7: autophagy gene 7; C12FDG: 5-dodecanoylaminofluorescein Di-β-D-Galactopyranoside; CDKN1A: cyclin dependent kinase inhibitor 1A; CDKN2A: cyclin dependent kinase inhibitor 2A; Ctl: control; DAPI: 4',6-diamidino-2-phenylindole, dilactate; ECM: extracellular matrix; GSH: L-glutathione reduced; H O : hydrogen peroxide; HLF: adult human lung fibroblasts; Ho: Hoechst 33342 (2'-[4-ethoxyphenyl]-5-[4-methyl-1-piperazinyl]-2.5'-bi-1[i]H[/i]-benzimidazole); HSC: hepatic stellate cells; LY: LY294002; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MTORC1/2: mechanistic target of rapamycin kinase complex 1/2; N: normal growth medium; NAC: N-acetyl-L-cysteine; PBS: phosphate-buffered saline; PDGFA: platelet derived growth factor subunit A; PRKCA/PKCα: protein kinase C alpha; PtdIns3K: class III phosphatidylinositol 3-kinase; PTEN: phosphatase and tensin homolog; R: rapamycin; RICTOR: RPTOR independent companion of MTOR complex 2; ROS: reactive oxygen species; RPTOR: regulatory associated protein of MTOR complex 1; SA-GLB1/β-gal: senescence-associated galactosidase beta 1; SGK1: serum/glucocorticoid regulated kinase 1; shRNA: short hairpin RNA; siCtl: control siRNA; siRNA: small interfering RNA; SQSTM1: sequestosome 1; SS: serum-free (serum starvation) medium; TP53: tumor protein p53; TUBA: tubulin alpha; V: vehicle.
Keywords
- Autophagy
- MTORC2
- myofibroblast
- rapamycin
- senescence
Mammalian species differ up to 100-fold in their aging rates and maximum lifespans. Long-lived mammals appear to possess traits that extend lifespan and healthspan. Genomic analyses have not revealed a single pro-longevity function that would account for all longevity effects. In contrast, it appears that pro-longevity mechanisms may be complex traits afforded by connections between metabolism and protein functions that are impossible to predict by genomic approaches alone. Thus, metabolomics and proteomics studies will be required to understand the mechanisms of longevity. Several examples are reviewed that demonstrate the naked mole rat (NMR) shows unique proteomic signatures that contribute to longevity by overcoming several hallmarks of aging. SIRT6 is also discussed as an example of a protein that evolves enhanced enzymatic function in long-lived species. Finally, it is shown that several longevity-related proteins such as Cip1/p21, FOXO3, TOP2A, AKT1, RICTOR, INSR, and SIRT6 harbor posttranslational modification (PTM) sites that preferentially appear in either short- or long-lived species and provide examples of crosstalk between PTM sites. Prospects of enhancing lifespan and healthspan of humans by altering metabolism and proteoforms with drugs that mimic changes observed in long-lived species are discussed.
Keywords
- SIRT6
- aging
- long-lived mammals
- naked mole rats
- proteomics
Osteoarthritis (OA) is a common multifactorial degenerative articular disease among the aging population. The current investigation aimed to elucidate the function of microRNA-495 (miR-495) in the development of OA. We found that miR-495 was upregulated in the cartilage of OA patients. Transfection of a miR-495 mimic into rat primary chondrocytes, human chondrocytes (HC) and SW1353 chondrosarcoma cells inhibited AKT1 expression, proliferation and scratch wound closure and induced apoptosis. Transfection of a miR-495 inhibitor produced an opposite effect. Furthermore, the production of cartilage degeneration-related substances was modified by miR-495. Luciferase reporter gene assay revealed that AKT1 is directly repressed by miR-495. Moreover, the levels of AKT1, p-S6 and p-mTOR diminished in chondrocytes overexpressing miR-495. AKT1 overexpression amplified p-S6 and p-mTOR levels as well as abolished miR-495 mimic-induced apoptosis and inhibition of proliferation. In the surgically induced rat OA model, apoptosis of chondrocytes and cartilage degeneration were remedied by the administration of a miR-495 antagomir. Moreover, there was an increased expression of AKT1. These findings indicate that miR-495 induces OA by targeting AKT1 and regulating the AKT/mTOR pathway. Therefore, miR-495 may be a prospective target for OA treatment.
Keywords
- AKT1
- MicroRNA-495
- apoptosis
- osteoarthritis
- senescence
Aging, obesity and sedentarism are among the most important predictors of cardiometabolic diseases. Aiming to reduce the impact of the combination of these three factors, we tested the therapeutic and preventive effects of exercise in aging and obese rats on the following cardiometabolic disease risk parameters: body fat, blood pressure, blood lipids, and glycemic homeostasis. Eighteen male Wistar rats (initial age = 4 months, and final age = 14 months) were randomly distributed into three aging and obese groups: sedentary, therapeutic exercise and preventive exercise. Food and caloric intake, body adiposity, muscle mass, cardiovascular parameters, biochemical markers, glycemic homeostasis, and gene expression of insulin-dependent, insulin-independent and insulin resistance pathways in skeletal muscle were evaluated. Therapeutic and preventive exercises were associated with higher food and caloric intake, and expression of TBC1D1 in the soleus muscle, as well as lower total cholesterol/HDL and LDL/HDL ratios, glucose levels at the end (90 min) of the glucose tolerance test and IKBKB expression in the gastrocnemius and soleus muscles. Only the preventive exercise improved the cardiovascular and body composition parameters, glucose tolerance, insulin resistance and insulin sensitivity, besides reducing total cholesterol, triglycerides, triglycerides/HDL ratio, plasmatic insulin and MAPK8 expression in soleus. The preventive exercise group also presented greater expression of INRS, IRS1, IRS2, PIK3CA, AKT1, and SLC2A4 in gastrocnemius and soleus, TBC1D1 in gastrocnemius, and AKT2 and PRKAA1 in soleus. Therapeutic exercise promoted some improvements on cardiometabolic parameters in aging and obese rats, however, the best benefits were achieved through the preventive exercise.
MeSH Terms
- AMP-Activated Protein Kinases
- Adipose Tissue
- Adiposity
- Aging
- Animals
- Blood Glucose
- Blood Pressure
- Body Composition
- Cardiovascular Diseases
- Cholesterol
- Disease Models, Animal
- Exercise Therapy
- Glucose Tolerance Test
- Homeostasis
- Insulin
- Insulin Resistance
- Lipids
- Lipoproteins, HDL
- Male
- Metabolic Diseases
- Mitogen-Activated Protein Kinase 8
- Muscle, Skeletal
- Obesity
- Physical Conditioning, Animal
- Proteins
- Proto-Oncogene Proteins c-akt
- Rats
- Rats, Wistar
- Triglycerides
Keywords
- Aerobic exercise
- Aging
- Insulin resistance
- Metabolic Diseases
- Obesity
The incidence of breast cancer increases with age until menopause, and breast cancer is more aggressive in younger women. The existence of epidemiological links between breast cancer and aging indicates that both processes share some common mechanisms of development. Oxidative stress is associated with both cancer susceptibility and aging. Here we observed that ERBB2-positive breast cancer, which developed in genetically heterogeneous ERBB2-positive transgenic mice generated by a backcross, is more aggressive in chronologically younger than in older mice (differentiated by the median survival of the cohort that was 79 weeks), similar to what occurs in humans. In this cohort, we estimated the oxidative biological age using a mathematical model that integrated several subphenotypes directly or indirectly related to oxidative stress. The model selected the serum levels of HDL-cholesterol and magnesium and total AKT1 and glutathione concentrations in the liver. The grade of aging was calculated as the difference between the predicted biological age and the chronological age. This comparison permitted the identification of biologically younger and older mice compared with their chronological age. Interestingly, biologically older mice developed more aggressive breast cancer than the biologically younger mice. Genomic regions on chromosomes 2 and 15 linked to the grade of oxidative aging were identified. The levels of expression of Zbp1 located on chromosome 2, a gene related to necroptosis and inflammation, positively correlated with the grade of aging and tumour aggressiveness. Moreover, the pattern of gene expression of genes linked to the inflammation and the response to infection pathways was enriched in the livers of biologically old mice. This study shows part of the complex interactions between breast cancer and aging.
MeSH Terms
- Aging
- Animals
- Breast Neoplasms
- Female
- Genes, erbB-2
- Glutathione
- Inflammation
- Liver
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Models, Theoretical
- Oxidative Stress
- Proto-Oncogene Proteins c-akt
- Quantitative Trait Loci
- Receptor, ErbB-2
- Transcriptome
Keywords
- Aging
- Biological age
- Breast cancer
- Mouse genetics
- Oxidative stress
- Subphenotypes
Tissue-specific effects of 17β-estradiol are delivered via both estrogen receptors and microRNAs (miRs). Menopause is known to affect the whole-body fat distribution in women. This investigation aimed at identifying menopause- and hormone replacement therapy (HRT)-associated miR profiles and miR targets in subcutaneous abdominal adipose tissue and serum from the same women. A discovery phase using array technology was performed in 13 women, including monozygotic twin pairs discordant for HRT and premenopausal young controls. Seven miRs, expressed in both adipose tissue and serum, were selected for validation phase in 34 women from a different cohort. An age/menopause-related increase of miRs-16-5p, -451a, -223-3p, -18a-5p, -19a-3p,-486-5p and -363-3p was found in the adipose tissue, but not in serum. MiR-19a-3p, involved in adipocyte development and estrogen signaling, resulted to be higher in HRT users in comparison with non-users. Among the identified targets, AKT1, BCL-2 and BRAF proteins showed lower expression in both HRT and No HRT users in comparison with premenopausal women. Unexpectedly, ESR1 protein expression was not modified although its mRNA was lower in No HRT users compared to premenopausal women and HRT users. Thus, both HRT and menopause appear to affect adipose tissue homeostasis via miR-mediated mechanism.
Keywords
- adipose tissue
- aging
- estrogen therapy
- miR-19a-3p
- microRNAs
Melanoma is an aggressive skin cancer that can rapidly metastasize to become fatal, if not diagnosed early. Despite recent therapeutic advances, management of melanoma remains difficult. Therefore, novel molecular targets and strategies are required to manage this neoplasm. This study was undertaken to determine the role of the sirtuin SIRT6 in melanoma. Employing a panel of human melanoma cells and normal human melanocytes, we found significant SIRT6 mRNA and protein upregulation in melanoma cells. Further, using a tissue microarray coupled with quantitative Vectra analysis, we demonstrated significant SIRT6 overexpression in human melanoma tissues. Lentiviral short hairpin RNA-mediated knockdown of SIRT6 in A375 and Hs 294T human melanoma cells significantly decreased cell growth, viability, and colony formation, induced G1-phase arrest and increased senescence-associated beta-galactosidase staining. As autophagy is important in melanoma and is associated with SIRT6, we used a qPCR array to study SIRT6 knockdown in A375 cells. We found significant modulation in several genes and/or proteins (decreases in AKT1, ATG12, ATG3, ATG7, BAK1, BCL2L1, CLN3, CTSB, CTSS, DRAM2, HSP90AA1, IRGM, NPC1, SQSTM1, TNF, and BECN1; increases in GAA, ATG10). Our data suggests that increased SIRT6 expression may contribute to melanoma development and/or progression, potentially via senescence-and autophagy-related pathways.
Keywords
- SIRT6
- autophagy
- melanoma
- senescence
- sirtuins
Senescent cells have lost their capacity for proliferation and manifest as irreversibly in cell cycle arrest. Many membrane receptors, including G protein-coupled receptors (GPCRs), initiate a variety of intracellular signaling cascades modulating cell division and potentially play roles in triggering cellular senescence response. GPCR kinases (GRKs) belong to a family of serine/threonine kinases. Although their role in homologous desensitization of activated GPCRs is well established, the involvement of the kinases in cell proliferation is still largely unknown. In this study, we isolated GRK4-GFP expressing HEK293 cells by fluorescence-activated cell sorting (FACS) and found that the ectopic expression of GRK4 halted cell proliferation. Cells expressing GRK4 (GRK4( )) demonstrated cell cycle G1/G0 phase arrest, accompanied with significant increase of senescence-associated-β-galactosidase (SA-β-Gal) activity. Expression profiling analysis of 78 senescence-related genes by qRT-PCR showed a total of 17 genes significantly changed in GRK4( ) cells (≥ 2 fold, p < 0.05). Among these, 9 genes - AKT1, p16 , p27 , p19 , IGFBP3, MAPK14, PLAU, THBS1, TP73 - were up-regulated, while 8 genes, Cyclin A2, Cyclin D1, CDK2, CDK6, ETS1, NBN, RB1, SIRT1, were down-regulated. The increase in cyclin-dependent kinase inhibitors (p16, p27) and p38 MAPK proteins (MAPK14) was validated by immunoblotting. Neither p53 nor p21 protein was detectable, suggesting no p53 activation in the HEK293 cells. These results unveil a novel function of GRK4 on triggering a p53-independent cellular senescence, which involves an intricate signaling network.
MeSH Terms
- Cell Division
- Cell Line, Tumor
- Cell Proliferation
- Cellular Senescence
- Flow Cytometry
- G-Protein-Coupled Receptor Kinase 4
- Gene Expression Profiling
- Gene Expression Regulation
- HEK293 Cells
- Humans
- MCF-7 Cells
- Transcriptome
- Tumor Suppressor Protein p53
Keywords
- Cellular senescence
- G protein-coupled receptor kinase 4
- Gene expression profiling
- p53-independent senescence
To investigate the effect of cinnamaldehyde and eugenol on the telomere-dependent senescence of stem cells. In addition, to search the probable targets of mentioned phytochemicals between human telomere interacting proteins (TIPs) using [i]in silico[/i] studies. Human adipose derived stem cells (hASCs) were studied under treatments with 2.5 µM/ml cinnamaldehyde, 0.1 µg/ml eugenol, 0.01% DMSO or any additive. The expression of TERT, AKT1 and DKC1 genes and the telomere length were assessed over 48-hr treatment. In addition, docking study was conducted to show probable ways through which phytochemicals interact with TIPs. Treated and untreated hASCs had undetectable TERT expression, but they had different AKT1 and DKC1 expression levels (CI=0.95; [i]P[/i]<0.05). The telomere lengths were reduced in phytochemicals treated with hASCs when compared with the untreated cells ([i]P[/i]<0.05). Docking results showed that the TIPs might be the proper targets for cinnamaldehyde and eugenol. Data mining showed there are many targets for cinnamaldehyde and eugenol in the intracellular environment. The general effect of cinnamaldehyde and eugenol is their induction of stem cell senescence. Therefore, they could be applicable as chemo-preventive or antineoplastic agents.
Keywords
- Aging
- Cinnamaldehyde
- Eugenol
- Stem cells
- Telomerase
- Telomere
Primary osteoporosis is a progressive bone disease that is characterized by a decrease in bone mass and density which can lead to an increased risk of fracture. Most of present treatments are effective for osteoporosis, but have limitations and side-effects. With the aging of the world population is increasing, the incidence of osteoporosis is rising. Therefore, the purpose of this study was to identify new candidate genes used as the therapeutic targets of primary osteoporosis. In this study, microarray data GSE35958 were downloaded from Gene Expression Omnibus, then the differentially expressed genes (DEGs) were identified by limma package. Gene Ontology (GO) and KEGG pathway enrichment analyses were performed for both up- and down-regulated DEGs using DAVID. In addition, the transcription factor analysis was conducted for DEGs. The protein-protein interaction (PPI) network was constructed by STRING and Cytoscape. Finally, CFinder was used to analyze the PPI sub-network. Totally, 327 up-regulated DEGs and 396 down-regulated DEGs were identified. The DEGs such as EGFR and AKT1 were mainly enriched in the pathway of focal adhesion. EGFR was also involved in cell adhesion based on GO enrichment analysis. Functional analysis of DEGs indicated that 26 transcription factors were screened. Moreover, EGFR, AKT1 and transcription factor CTNNB1 were the key nodes with high degrees according to PPI network and sub-network. The literature suggested that AKT1, EGFR and CTNNB1 were closely related to osteoblastic differentiation and osteoclastogenesis. Some crucial DEGs such as EGFR, AKT1 and CTNNB1 might be connected with primary osteoporosis and could be used as therapeutic targets of osteoporosis.
MeSH Terms
- Aging
- Down-Regulation
- Gene Expression
- Gene Expression Profiling
- Humans
- Osteoporosis
- Protein Interaction Maps
- Transcription Factors
- Up-Regulation
- beta Catenin
Although tyrosine kinase inhibitor (TKI) therapies are highly effective in the treatment of chronic myeloid leukemia (CML), frequent recurrence limits their usage and demands new approaches for CML therapy. Stress-induced premature senescence (SIPS) is considered a potential anticancer treatment, but the underlying mechanism remains elusive. Here, we report that Sirtinol, a known SIRT1 inhibitor, induces premature senescence and growth arrest in K562 CML cells. Chromobox homolog 8 (CBX8) suppresses the Sirtinol-induced premature senescence, which is reversed by CBX8 knockdown. Upon Sirtinol treatment, the phosphorylation of AKT1, p27KIP1 and RB is severely downregulated. However, CBX8 overexpression enhances phosphorylation and, thereby, promotes the transcriptional activity of E2F1, both of which are impaired upon CBX depletion. These data suggest that CBX8 modulates SIPS through the RB-E2F1 pathway in CML cells and provide important insight into its application in CML treatment.
MeSH Terms
- Antineoplastic Agents
- Benzamides
- Cell Cycle Checkpoints
- Cellular Senescence
- Drug Antagonism
- E2F1 Transcription Factor
- Humans
- K562 Cells
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive
- Naphthols
- Oncogene Protein v-akt
- Polycomb Repressive Complex 1
- Retinoblastoma Protein
- Signal Transduction
Keywords
- CBX8
- Leukemia
- Premature senescence
- RB-E2F1
- SIRT1
FOXO3, AKT1 and IGF-2R are critical members of the insulin/IGF-1 signaling pathway. Previous studies showed that polymorphisms (SNPs) in FOXO3, AKT1 and IGF-2R were associated with human longevity in Caucasian population. However, the association of these SNPs in different ethnic groups is often inconsistent. Here, we investigated the association of genetic variants in three genes with human longevity in Han Chinese population. Twelve SNPs from FOXO3, AKT1 and IGF-2R were selected and genotyped in 1202 long-lived individuals (nonagenarians and centenarians) and younger individuals. Rs9486902 of FOXO3 was found to be associated with human longevity in both genders combined in this study (allelic P = 0.002, corrected P = 0.024). The other eleven SNPs were not significantly associated with human longevity in Han Chinese population. The haplotypes TTCTT, CCTTC and CTCCT of FOXO3 as well as GGTCGG and GGTCAG of AKT1 were shown to have a significant difference between case and control (P =0.006, 2.78×10-5, 4.68×10-6, 0.003,0.005, respectively). The estimated prevalence of diabetes and prediabetes in long-lived individuals was significantly lower than in common adult populations (P = 0.001, 2.3×10-26) .Therefore, the search for longevity-associated genes provides the identification of new potential targets beneficial for the treatment of diabetes.
MeSH Terms
- Adult
- Aged, 80 and over
- Asian Continental Ancestry Group
- China
- Diabetes Mellitus
- Female
- Forkhead Box Protein O3
- Forkhead Transcription Factors
- Gene Frequency
- Genotype
- Haplotypes
- Humans
- Linkage Disequilibrium
- Longevity
- Male
- Polymorphism, Single Nucleotide
- Prediabetic State
- Prevalence
- Proto-Oncogene Proteins c-akt
- Receptor, IGF Type 2
- Young Adult
Keywords
- AKT1
- FOXO3
- Gerotarget
- IGF-2R
- human longevity
- single nucleotide polymorphism (SNP)
This review is devoted to the description of research achievements in genetics of aging and longevity. It represents a certain interest for understanding of a problems of aging as a whole. There is a huge amount of results of diverse genetic studies of aging and longevity. Studies were performed with using different experimental strategies on model organisms or samples from different human populations of the world. The search for aging and longevity genes was carried out within international consortiums. The first results of whole genome sequences of super-centenarians were received. The genes influencing life expectancy were revealed in organisms of different systematic groups. Many of these genes are evolutionarily conservative. Associations between APOE, FOXO1A, FOXO3A, AKT1 gene polymorphisms and human longevity were confirmed in independent studies.
MeSH Terms
- Aged, 80 and over
- Aging
- Humans
- Life Expectancy
- Longevity
- Molecular Biology
Phosphoinositides, lipid-signaling molecules, participate in diverse brain processes within a wide metabolic cascade. Gene transcriptional networks coordinately regulate the phosphoinositide cascade during human brain Development and Aging. We used the public BrainCloud database for human dorsolateral prefrontal cortex to examine age-related expression levels of 49 phosphoinositide metabolic genes during Development (0 to 20 years) and Aging (21 years). We identified three groups of partially overlapping genes in each of the two intervals, with similar intergroup correlations despite marked phenotypic differences between Aging and Development. In each interval, ITPKB, PLCD1, PIK3R3, ISYNA1, IMPA2, INPPL1, PI4KB, and AKT1 are in Group 1, PIK3CB, PTEN, PIK3CA, and IMPA1 in Group 2, and SACM1L, PI3KR4, INPP5A, SYNJ1, and PLCB1 in Group 3. Ten of the genes change expression nonlinearly during Development, suggesting involvement in rapidly changing neuronal, glial and myelination events. Correlated transcription for some gene pairs likely is facilitated by colocalization on the same chromosome band. Stable coordinated gene transcriptional networks regulate brain phosphoinositide metabolic pathways during human Development and Aging.
MeSH Terms
- Adolescent
- Adult
- Aging
- Child
- Child, Preschool
- Gene Expression
- Humans
- Infant
- Infant, Newborn
- Phosphatidylinositols
- Prefrontal Cortex
- Young Adult
How cellular stresses up-regulate autophagy is not fully understood. One potential regulator is the Drosophila melanogaster protein Acinus (Acn), which is necessary for autophagy induction and triggers excess autophagy when overexpressed. We show that cell type-specific regulation of Acn depends on proteolysis by the caspase Dcp-1. Basal Dcp-1 activity in developing photoreceptors is sufficient for this cleavage without a need for apoptosis to elevate caspase activity. On the other hand, Acn was stabilized by loss of Dcp-1 function or by the presence of a mutation in Acn that eliminates its conserved caspase cleavage site. Acn stability also was regulated by AKT1-mediated phosphorylation. Flies that expressed stabilized forms of Acn, either the phosphomimetic Acn(S641,731D) or the caspase-resistant Acn(D527A), exhibited enhanced basal autophagy. Physiologically, these flies showed improvements in processes known to be autophagy dependent, including increased starvation resistance, reduced Huntingtin-induced neurodegeneration, and prolonged life span. These data indicate that AKT1 and caspase-dependent regulation of Acn stability adjusts basal autophagy levels.
MeSH Terms
- Amino Acid Sequence
- Animals
- Apoptosis
- Autophagy
- Binding Sites
- Caspases
- Conserved Sequence
- Drosophila Proteins
- Drosophila melanogaster
- Gene Expression Regulation
- Longevity
- Molecular Sequence Data
- Mutation
- Protein Stability
- Proto-Oncogene Proteins c-akt
- Sequence Alignment
- Transcription Factors
Age plays a major role in tumor incidence and is an important consideration when modeling the carcinogenesis process or estimating cancer risks. Epidemiological data show that from adolescence through middle age, cancer incidence increases with age. This effect is commonly attributed to a lifetime accumulation of cellular, particularly DNA, damage. However, during middle age the incidence begins to decelerate and, for many tumor sites, it actually decreases at sufficiently advanced ages. We investigated if the observed deceleration and potential decrease in incidence could be attributed to a decreased capacity of older hosts to support tumor progression, and whether HZE [high atomic number (Z), high energy (E)] radiation differentially modulates tumor progression in young vs. middle-age hosts, issues that are relevant to estimating carcinogenesis risk for astronauts. Lewis lung carcinoma (LLC) cells were injected into syngeneic mice (143 and 551 days old), which were then subject to whole-body (56)Fe irradiation (1 GeV/amu). Three findings emerged: (1) among unirradiated animals, substantial inhibition of tumor progression and significantly decreased tumor growth rates were seen for middle-aged mice compared to young mice, (2) whole-body (56)Fe irradiation inhibited tumor progression in both young and middle-aged mice (with greater suppression seen in case of young animals), with little effect on tumor growth rates, and (3) (56)Fe irradiation suppressed tumor progression in young mice to a degree that was not significantly different than transiting from young to middle-aged. Thus, (56)Fe irradiation acted similar to aging with respect to tumor progression. We further investigated the molecular underpinnings driving the radiation modulation of tumor dynamics in young and middle-aged mice. Through global gene expression analysis, the key players, FASN, AKT1 and the CXCL12/CXCR4 complex, were determined to be contributory. In sum, these findings demonstrated a reduced capacity of middle-aged hosts to support the progression phase of carcinogenesis and identify molecular factors that contribute to HZE radiation modulation of tumor progression as a function of age.
MeSH Terms
- Aging
- Animals
- Biomarkers, Tumor
- Cell Line, Tumor
- Cell Proliferation
- Disease Progression
- Extraterrestrial Environment
- Iron
- Male
- Mice
- Mice, Inbred C57BL
- Neoplasms, Radiation-Induced
- Protein Interaction Maps
- Risk
- Transcriptome
- Tumor Burden
In addition to APOE and FOXO3, AKT1 has recently been suggested as a third consistent longevity gene, with variants in AKT1 found to be associated with human lifespan in two previous studies. Here, we evaluated AKT1 as a longevity-associated gene across populations by attempting to replicate the previously identified variant rs3803304 as well as by analyzing six additional AKT1 single-nucleotide polymorphisms, thus capturing more of the common variation in the gene. The study population was 2996 long-lived individuals (nonagenarians and centenarians) and 1840 younger controls of Danish and German ancestry. None of the seven SNPs tested were significantly associated with longevity in either a case-control or a longitudinal setting, although a supportive nominal indication of a disadvantageous effect of rs3803304 was found in a restricted group of Danish centenarian men. Overall, our results do not support AKT1 as a universal longevity-associated gene.
MeSH Terms
- Aged, 80 and over
- Denmark
- Female
- Genotype
- Germany
- Humans
- Longevity
- Male
- Models, Genetic
- Polymorphism, Single Nucleotide
- Proto-Oncogene Proteins c-akt
Converging lines of evidence suggest that AKT1 is a major mediator of the responses to insulin,insulin-like growth factor 1 (IGF1), and glucose. AKT1 also plays a key role in the regulation of both muscle cell hypertrophy and atrophy. We hypothesized that AKT1 variants may play a role in the endophenotypes that makeup metabolic syndrome. We studied a 12-kb region including the first exon of the AKT1 gene for association with metabolic syndrome-related phenotypes in four study populations [FAMUSS cohort (n = 574; age 23.7 ± 5.7 years), Strong Heart Study (SHS) (n = 2,134; age 55.5 ± 7.9 years), Dynamics of Health, Aging and Body Composition (Health ABC) (n = 3,075; age 73.6 ± 2.9 years), and Studies of a Targeted Risk Reduction Intervention through Defined Exercise (STRRIDE)(n = 175; age 40–65 years)]. We identified a three SNP haplotype that we call H1, which represents the ancestral alleles eles at the three loci and H2, which represents the derived alleles at the three loci. In young adult European Americans (FAMUSS), H1 was associated with higher fasting glucose levels in females. In middle age Native Americans (SHS), H1 carriers showed higher fasting insulin and HOMA in males, and higher BMI in females. Inolder African-American and European American subjects(Health ABC) H1 carriers showed a higher incidence of metabolic syndrome. Homozygotes for the H1 haplotype showed about twice the risk of metabolic syndrome in both males and females (p < 0.001). In middle-aged European Americans with insulin resistance (STRRIDE) studied by intravenous glucose tolerance test (IVGTT), H1 carriers showed increased insulin resistance due to the Sg component (p = 0.021). The 12-kb haplotype is a risk factor for metabolic syndrome and insulin resistance that needs to be explored in further populations.
MeSH Terms
- Adult
- Aged
- Aged, 80 and over
- Aging
- Female
- Humans
- Insulin Resistance
- Male
- Metabolic Syndrome
- Middle Aged
- Polymorphism, Single Nucleotide
- Proto-Oncogene Proteins c-akt
- Young Adult
The insulin/IGF1 signaling pathways affect lifespan in several model organisms, including worms, flies and mice. To investigate whether common genetic variation in this pathway influences lifespan in humans, we genotyped 291 common variants in 30 genes encoding proteins in the insulin/IGF1 signaling pathway in a cohort of elderly Caucasian women selected from the Study of Osteoporotic Fractures (SOF). The cohort included 293 long-lived cases (lifespan > or = 92 years (y), mean /- standard deviation (SD) = 95.3 /- 2.2y) and 603 average-lifespan controls (lifespan < or = 79y, mean = 75.7 /- 2.6y). Variants were selected for genotyping using a haplotype-tagging approach. We found a modest excess of variants nominally associated with longevity. Nominally significant variants were then replicated in two additional Caucasian cohorts including both males and females: the Cardiovascular Health Study and Ashkenazi Jewish Centenarians. An intronic single nucleotide polymorphism in AKT1, rs3803304, was significantly associated with lifespan in a meta-analysis across the three cohorts (OR = 0.78 95%CI = 0.68-0.89, adjusted P = 0.043); two intronic single nucleotide polymorphisms in FOXO3A demonstrated a significant lifespan association among women only (rs1935949, OR = 1.35, 95%CI = 1.15-1.57, adjusted P = 0.0093). These results demonstrate that common variants in several genes in the insulin/IGF1 pathway are associated with human lifespan.
MeSH Terms
- Aged
- Aged, 80 and over
- Female
- Follow-Up Studies
- Forkhead Box Protein O3
- Forkhead Transcription Factors
- Genome, Human
- Genotype
- Humans
- Insulin
- Insulin-Like Growth Factor I
- Longevity
- Male
- Osteoporosis
- Polymorphism, Single Nucleotide
- Proto-Oncogene Proteins c-akt
- Signal Transduction