Ageing effects on the expression of cell defence genes after UVA irradiation in human male cutaneous fibroblasts using cDNA arrays

Cystathionine γ-Lyase Attenuates Vascular Smooth Muscle Cell Senescence via Foxm1-Gas1 Pathway to Mediate Arterial Stiffness

Aims: Arterial stiffness, a hallmark of vascular aging, significantly contributes to hypertension and impaired organ perfusion. Vascular smooth muscle cell (VSMC) dysfunction, particularly VSMC senescence and its interaction with stiffness, is crucial in the pathogenesis of arterial stiffness. Although hydrogen sulfide (H2S) and its key enzyme cystathionine γ-lyase (CSE) are known to play roles in cardiovascular diseases, their effects on arterial stiffness are not well understood. Methods & Results: First, we observed a downregulation of CSE/H2S in the aortic media during biological aging and angiotensin II (AngII)-induced aging. The VSMC-specific CSE knockout mice were created by loxp-cre (Tagln-cre) system and which exacerbated AngII-induced aortic aging and stiffness in vivo and VSMC senescence and stiffness in vitro. Conversely, the CSE agonist norswertianolin mitigated these effects. Next, we identified growth arrest-specific 1 (Gas1) as a crucial target of CSE/H2S and found it to be a downstream target gene of forkhead box protein M1 (Foxm1). siRNA knockdown Foxm1 increased Gas1 transcription and reduced the protective effects of H2S on VSMC senescence and stiffness. Finally, we demonstrated that CSE/H2S sulfhydrates Foxm1 at the C210 site, regulating its nuclear translocation and activity, thus reducing VSMC senescence and stiffness. Innovation: Our findings highlight the protective role of CSE/H2S in arterial stiffness, emphasizing the novel contributions of CSE, Gas1, and Foxm1 to VSMC senescence and stiffness. Conclusion: Endogenous CSE/H2S in VSMCs reduces VSMC senescence and stiffness, thereby attenuating arterial stiffness and aging, partly through sulfhydration-mediated activation of Foxm1 and subsequent inhibition of Gas1 signaling pathways.

Exploring the Genetic Landscape of Vitiligo in the Pura Raza Español Horse: A Genomic Perspective

Vitiligo is a depigmentation autoimmune disorder characterized by the progressive loss of melanocytes leading to the appearance of patchy depigmentation of the skin. The presence of vitiligo in horses is greater in those with grey coats. The aim of this study was therefore to perform a genome-wide association study (GWAS) to identify genomic regions and putative candidate loci associated with vitiligo depigmentation and susceptibility in the Pura Raza Español population. For this purpose, we performed a wssGBLUP (weighted single step genomic best linear unbiased prediction) using data from a total of 2359 animals genotyped with Affymetrix Axiom™ Equine 670 K and 1346 with Equine GeneSeek Genomic Profiler™ (GGP) Array V5. A total of 60,136 SNPs (single nucleotide polymorphisms) present on the 32 chromosomes from the consensus dataset after quality control were employed for the analysis. Vitiligo-like depigmentation was phenotyped by visual inspection of the different affected areas (eyes, mouth, nostrils) and was classified into nine categories with three degrees of severity (absent, slight, and severe). We identified one significant genomic region for vitiligo around the eyes, eight significant genomic regions for vitiligo around the mouth, and seven significant genomic regions for vitiligo around the nostrils, which explained the highest percentage of variance. These significant genomic regions contained candidate genes related to melanocytes, skin, immune system, tumour suppression, metastasis, and cutaneous carcinoma. These findings enable us to implement selective breeding strategies to decrease the incidence of vitiligo and to elucidate the genetic architecture underlying vitiligo in horses as well as the molecular mechanisms involved in the disease's development. However, further studies are needed to better understand this skin disorder in horses.

Sonic hedgehog signalling pathway contributes in age-related disorders and Alzheimer's disease

Alzheimer's disease (AD) is caused by the aging process and manifested by cognitive deficits and progressive memory loss. During aging, several conditions, including hypertension, diabetes, and cholesterol, have been identified as potential causes of AD by affecting Sonic hedgehog (Shh) signalling. In addition to being essential for cell differentiation and proliferation, Shh signalling is involved in tissue repair and the prevention of neurodegeneration. Neurogenesis is dependent on Shh signalling; inhibition of this pathway results in neurodegeneration. Several protein-protein interactions that are involved in Shh signalling are implicated in the pathophysiology of AD like overexpression of the protein nexin-1 inhibits the Shh pathway in AD. A protein called Growth Arrest Specific-1 works with another protein called cysteine dioxygenase (CDO) to boost Shh signalling. CDO is involved in the development of the central nervous system (CNS). Shh signalling strengthened the blood brain barrier and therefore prevent the entry of amyloid beta and other toxins to the brain from periphery. Further, several traditional remedies used for AD and dementia, including Epigallocatechin gallate, yokukansan, Lycium barbarum polysaccharides, salvianolic acid, and baicalin, are known to stimulate the Shh pathway. In this review, we elaborated that the Shh signalling exerts a substantial influence on the pathogenesis of AD. In this article, we have tried to explore the various possible connections between the Shh signalling and various known pathologies of AD.

Piper betle L. Modulates Senescence-Associated Genes Expression in Replicative Senescent Human Diploid Fibroblasts

Piper betle (PB) is a traditional medicine that is widely used to treat different diseases around Asian region. The leaf extracts contain various bioactive compounds, which were reported to have antidiabetic, antibacterial, anti-inflammatory, antioxidant, and anticancer effects. In this study, the effect of PB aqueous extracts on replicative senescent human diploid fibroblasts (HDFs) was investigated by determining the expressions of senescence-associated genes using quantitative PCR. Our results showed that PB extracts at 0.4 mg/ml can improve cell proliferation of young (143%), presenescent (127.3%), and senescent (157.3%) HDFs. Increased expressions of PRDX6, TP53, CDKN2A, PAK2, and MAPK14 were observed in senescent HDFs compared to young and/or presenescent HDFs. Treatment with PB extracts modulates the transcriptional profile changes in senescent HDFs. By contrast, expressions of SOD1 increased, whereas GPX1, PRDX6, TP53, CDKN2A, PAK2, and MAPK14 were decreased in PB-treated senescent HDFs compared to untreated senescent HDFs. In conclusion, this study indicates the modulation of PB extracts on senescence-associated genes expression of replicative senescent HDFs. Further studies warrant determining the mechanism of PB in modulating replicative senescence of HDFs through these signaling pathways.

Identification of Potential Key lncRNAs and Genes Associated with Aging Based on Microarray Data of Adipocytes from Mice

Objective. This study aimed to screen potential crucial lncRNAs and genes involved in aging. Methods. The data of 9 peripheral white adipocytes, respectively, taken from male C57BL/6J mice (6 months, 14 months, and 18 months of age) in GSE25905 were used in this study. Differentially time series expressed lncRNA genes (DE-lncRNAs) and mRNA genes (DEGs) were identified. After cluster analysis of lncRNAs expression pattern, target genes of DE-lncRNAs were predicted from the DEGs, and functional analysis for target genes was conducted. Results. A total of 8301 time series-related DEGs and 43 time series-related DE-lncRNAs were identified. Among them, 41 DE-lncRNAs targeted 1880 DEGs. The DEGs positively regulated by DE-lncRNAs were mainly related to the development of blood vessel and the pathways of cholesterol biosynthesis and elastic fibre formation. Furthermore, the DEGs negatively regulated by DE-lncRNAs were correlated with protein metabolism. Conclusion. These DE-lncRNAs and DEGs are potentially involved in the process of aging.

Modifications in stromal extracellular matrix of aged corneas can be induced by ultraviolet A irradiation

With age, structural and functional changes can be observed in human cornea. Some studies have shown a loss of corneal transparency and an increase in turbidity associated with aging. These changes are caused by modifications in the composition and arrangement of extracellular matrix in the corneal stroma. In human skin, it is well documented that exposure to solar radiation, and mainly to the UVA wavelengths, leads to phenotypes of photoaging characterized by alteration in extracellular matrix of the dermis. Although the cornea is also exposed to solar radiation, the extracellular matrix modifications observed in aging corneas have been mainly attributed to chronological aging and not to solar exposure. To ascertain the real implication of UVA exposure in extracellular matrix changes observed with age in human cornea, we have developed a model of photoaging by chronically exposing corneal stroma keratocytes with a precise UVA irradiation protocol. Using this model, we have analyzed UVA-induced transcriptomic and proteomic changes in corneal stroma. Our results show that cumulative UVA exposure causes changes in extracellular matrix that are found in corneal stromas of aged individuals, suggesting that solar exposure catalyzes corneal aging. Indeed, we observe a downregulation of collagen and proteoglycan gene expression and a reduction in proteoglycan production and secretion in response to cumulative UVA exposure. This study provides the first evidence that chronic ocular exposure to sunlight affects extracellular matrix composition and thus plays a role in corneal changes observed with age.

UVA irradiation induced heme oxygenase-1: a novel phototherapy for morphea

Long wave UVA radiation (340-400 nm) causes detrimental as well as beneficial effects on human skin. Studies of human skin fibroblasts irradiated with UVA demonstrate increased expression of both antifibrotic heme oxygenase-1 (HO-1) and matrix metalloproteinase 1 (MMP-1). The use of UVA-induced MMP-1 is well-studied in treating skin fibrotic conditions such as localized scleroderma, now called morphea. However, the role that UVA-induced HO-1 plays in phototherapy of morphea has not been characterized. In the present manuscript, we have illustrated and reviewed the biological function of HO-1 and the use of UVA1 wavebands (340-400 nm) for phototherapy; the potential use of HO-1 induction in UVA therapy of morphea is also discussed.

Biological and metabolic response in STS-135 space-flown mouse skin

There is evidence that space flight condition-induced biological damage is associated with increased oxidative stress and extracellular matrix (ECM) remodeling. To explore possible mechanisms, changes in gene expression profiles implicated in oxidative stress and in ECM remodeling in mouse skin were examined after space flight. The metabolic effects of space flight in skin tissues were also characterized. Space Shuttle Atlantis (STS-135) was launched at the Kennedy Space Center on a 13-day mission. Female C57BL/6 mice were flown in the STS-135 using animal enclosure modules (AEMs). Within 3-5 h after landing, the mice were euthanized and skin samples were harvested for gene array analysis and metabolic biochemical assays. Many genes responsible for regulating production and metabolism of reactive oxygen species (ROS) were significantly (p < 0.05) altered in the flight group, with fold changes >1.5 compared to AEM control. For ECM profile, several genes encoding matrix and metalloproteinases involved in ECM remodeling were significantly up-/down-regulated following space flight. To characterize the metabolic effects of space flight, global biochemical profiles were evaluated. Of 332 named biochemicals, 19 differed significantly (p < 0.05) between space flight skin samples and AEM ground controls, with 12 up-regulated and 7 down-regulated including altered amino acid, carbohydrate metabolism, cell signaling, and transmethylation pathways. Collectively, the data demonstrated that space flight condition leads to a shift in biological and metabolic homeostasis as the consequence of increased regulation in cellular antioxidants, ROS production, and tissue remodeling. This indicates that astronauts may be at increased risk for pathophysiologic damage or carcinogenesis in cutaneous tissue.

Role of oxidative stress in chemical allergens induced skin cells activation

Allergic contact dermatitis (ACD) is an important occupational and environmental disease caused by topical exposure to chemical allergens. It describes the adverse effects that may results when exposure to a chemical elicits a T cell-mediated inflammatory skin disease. The ability of contact sensitizers to induce the oxidative stress pathway in keratinocytes and dendritic cells has been confirmed by several authors. Reactive oxygen species (ROS) can serve as essential second messengers mediating cellular responses resulting in immune cells activation. Oxidative stress may be the starter point, as it leads to the activation of transcription factors and signaling pathways, including NF-kB and p38 MAPK, which leads to the release of cytokines and chemokines. ROS are also involved in the activation of the NLRP3/NALP3 inflammasome, which is required to direct the proteolytic maturation of inflammatory cytokines such as IL-1β and IL-18, which are all integral to the process of dendritic cells mobilization, migration and functional maturation. Moreover, emerging evidence correlates ROS to changes in the constitution of the extracellular microenvironment found to facilitate ACD. The purpose of this review is to provide both conceptual and technical frameworks on the role of oxidative stress in chemical allergy.

Mesenchymal activin-A overcomes defective human trisomy 21 trophoblast fusion

Placental development is markedly abnormal in trisomy 21 (T21) pregnancies. We hypothesized that abnormal paracrine cross talk between the fetal mesenchymal core and the trophoblast might be involved in the defect of syncytiotrophoblast formation and function. In a large series of primary cultured human cytotrophoblasts isolated from second-trimester control (n = 44) and T21 placentae (n = 71), abnormal trophoblast fusion and differentiation was observed in more than 90% of T21 cases. We then isolated and cultured villous mesenchymal cells from control (n = 10) and T21 placentae (n = 8) and confirmed their fetal origin. Conditioned medium of control mesenchymal cells overcame the abnormal trophoblast fusion of T21 cytotrophoblasts by activating the TGFβ signaling pathway, as shown by the phosphospecific protein microarray analysis and the use of TGFβ signaling pathway antagonists. Using protein arrays, we further analyzed the cytokines present in the conditioned medium from control and T21 mesenchymal cells. Activin-A was identified as strongly secreted by cells from both sources, but at a significantly (P < 0.01) lower level in the case of T21 mesenchymal cells. Recombinant activin-A stimulated T21 trophoblast fusion. Blocking activin-A antibody inhibited the fusion induced by conditioned medium and exogenous activin-A. Furthermore, follistatin, an activin-A binding protein largely secreted by T21 mesenchymal cells, inhibited the conditioned medium fusogenic activity. These results show that the defective trophoblast fusion and differentiation associated with T21 can be overcome in vitro and reveal the key role of the fetal mesenchymal core in human trophoblast differentiation.

Effect of overexpression of wild-type p53 on POLD1 expression and malignant cell behavior in human hepatocellular carcinoma cell line SMMC-7721

AIM: To investigate the impact of overexpression of wild-type p53 on cell proliferation and malignant phenotype in human hepatocellular carcinoma cell line SMMC-7721 and to explore possible mechanism involved.

METHODS: Enhanced green fluorescence protein gene-containing eukaryotic expression plasmids expressing p53-specific small interfering RNA (shRNA) (p53-siRNA) or wild-type p53 (pEGFP-p53) were constructed and introduced into SMMC-7721 cells by Lipofection-2000-mediated transfection. Meanwhile, the pEGFP-C1 empty vector was also transfected into SMMC-7721 cells. Cell lines stably expressing p53-siRNA, pEGFP-p53 or pEGFP-C1 were screened in medium containing G418. After transfection, the expression of p53 and POLD1 mRNAs was detected by RT-PCR. The changes in malignant cell behavior were determined by cell growth curve determination and colony formation assay.

RESULTS: Compared to control SMMC-7721 cells, p53 mRNA expression was increased and POLD1 gene expression was decreased in SMMC-7721 cells transfected with the plasmid carrying wild-type p53 gene, while p53 mRNA expression was reduced and POLD1 mRNA expression was increased in SMMC-7721 cells transfected with the plasmid carrying p53-siRNA. MTT results showed that cell growth rate was faster in SMMC-7721 cells transfected with the plasmid carrying p53-siRNA than in control SMMC-7721 cells, but was slower in SMMC-7721 cells transfected with the plasmid carrying wild-type p53 gene than in control cells. Colony formation assay showed that colony formation rate was lower in SMMC-7721 cells transfected with the plasmid carrying wild-type p53 gene than in control cells (38.1% vs 52.6%, P < 0.05), but was higher in cells tranfected with the plasmid carrying p53-siRNA than in control cells (72.6% vs 52.6%, P < 0.05). High expression of wild-type p53 inhibited POLD1 transcription and cell proliferation, while low expression of wild-type p53 promoted POLD1 transcription and cell proliferation.

CONCLUSION: Wild-type p53 controls liver cancer cell proliferation and malignant phenotype possibly by regulating POLD1 expression.

In vitro antioxidant and antigenotoxic potentials of 3,5-O-di-galloylquinic acid extracted from Myrtus communis leaves and modulation of cell gene expression by H2O2

3,5-O-di-galloylquinic acid (DGQA) purified from leaves of Myrtus communis was investigated for its antioxidative, antiproliferative and antigenotoxic activities. Antioxidant activity was determined by the ability of the compound to inhibit lipid peroxidation induced by H(2)O(2) in the K562 cell line. The pure molecule displayed an important malondialdehyde formation inhibition percentage (82.2%). Moreover, this compound exhibited an inhibitory effect against H(2)O(2)-induced genotoxicity, using the comet assay. A protective effect of the same molecule was also revealed when assessing the gene expression of the chronic myelogenous leukemia cell line (K562), stressed with H(2)O(2). For this purpose, we used a cDNA-microarray containing 82 genes related to cell defense, essentially represented by antioxidant and DNA repair proteins. We found that DGQA increase the activity of antioxidant enzymes family and the activity of DNA repair enzymes. Taken together, these observations provide evidence that the DGQA is able to protect cells against oxidative stress.

Differential expression of oxidative stress and extracellular matrix remodeling genes in low- or high-dose-rate photon-irradiated skin

Changes in the expression of genes implicated in oxidative stress and in extracellular matrix (ECM) remodeling and selected protein expression profiles in mouse skin were examined after exposure to low-dose-rate or high-dose-rate photon irradiation. ICR mice received whole-body γ rays to total doses of 0, 0.25, 0.5 and 1 Gy at dose rates of 50 cGy/h or 50 cGy/min. Skin tissues were harvested for characterization at 4 h after irradiation. For oxidative stress after low-dose-rate exposure, 0.25, 0.5 and 1 Gy significantly altered 27, 23 and 25 genes, respectively, among 84 genes assessed (P < 0.05). At doses as low as 0.25 Gy, many genes responsible for regulating the production of reactive oxygen species (ROS) were significantly altered, with changes >2-fold compared to 0 Gy. For an ECM profile, 18-20 out of 84 genes were significantly up- or downregulated after low-dose-rate exposure. After high-dose-rate irradiation, of 84 genes associated with oxidative stress, 16, 22 and 22 genes were significantly affected after 0.25, 0.5 and 1 Gy, respectively. Compared to low-dose-rate radiation, high-dose-rate exposure resulted in different ECM gene expression profiles. The most striking changes after low-dose-rate or high-dose-rate exposure on ECM profiles were on genes encoding matrix metalloproteinases (MMPs), e.g., Mmp2 and Mmp15 for low dose rate and Mmp9 and Mmp11 for high dose rate. Immunostaining for MMP-2 and MMP-9 proteins showed radiation dose rate-dependent differences. These data revealed that exposure to low total doses with low-dose-rate or high-dose-rate photon radiation induced oxidative stress and ECM-associated alterations in gene expression profiles. The expression of many genes was differentially regulated by different total dose and/or dose-rate regimens.

Growth arrest-specific 1 binds to and controls the maturation and processing of the amyloid-beta precursor protein

Alzheimer's disease (AD), the most common neurodegenerative disorder, is characterized by cerebral deposition of amyloid-β (Aβ), a series of peptides derived from the processing of the amyloid-β precursor protein (APP). To identify new candidate genes for AD, we recently performed a transcriptome analysis to screen for genes preferentially expressed in the hippocampus and located in AD linkage regions. This strategy identified CALHM1 (calcium homeostasis modulator 1), a gene modulating AD age at onset and Aβ metabolism. Here, we focused our attention on another candidate identified using this screen, growth arrest-specific 1 (Gas1), a gene involved in the central nervous system development. We found that Gas1 formed a complex with APP and controlled APP maturation and processing. Gas1 expression inhibited APP full glycosylation and routing to the cell surface by leading to a trafficking blockade of APP between the endoplasmic reticulum and the Golgi. Gas1 expression also resulted in a robust inhibition of APP transport into multivesicular bodies, further demonstrating that Gas1 negatively regulated APP intracellular trafficking. Consequently, Gas1 overexpression led to a reduction in Aβ production, and conversely, Gas1 silencing in cells expressing endogenously Gas1 increased Aβ levels. These results suggest that Gas1 is a novel APP-interacting protein involved in the control of APP maturation and processing.

Influence of stress on extracellular matrix and integrin biology

Dynamic interactions between cells and extracellular matrix (ECM) through integrins influence most cellular functions. Normal cells, but even more, tumor cells are subjected to different forms of stress, including ischemia, radical oxygen species production, starvation, mechanical stress or genotoxic insults due to anti-cancer drugs or irradiation. In these situations, an adaptative cellular response occurs, integrating a complex network of intracellular signaling modules, which, depending on stress intensity, may result to either damage repair followed by complete restitution of cellular functions, or programmed cell death. Because of its implication in oncogenesis and anti-cancer therapy, cellular stress response has been thoroughly investigated. However, most of these studies have been performed in the context of isolated cells without taking into consideration that most cells are part of the tissue within which they interact with ECM through integrin. Few studies have described the influence of stress on cell-to-ECM interaction. However, one can speculate that, in these conditions, cells could functionally interact with protein microenvironment either to create positive interactions to survive (for example by facilitating protective pathways) or negative interaction to die (for example by facilitating detachment). In this review, we summarize the knowledge relative to the influence of different stress modalities on ECM remodeling, integrin expression and/or function modifications, and possible functional consequences, independently from the cellular model as these findings came from a large variety of cells (mesenchymal, endothelial, muscular, epithelial and glandular) and fields of application (cancer, vascular biology and tissue engineering). Most studies support the general notion that non-lethal stress favors ECM stiffness, integrin activation and enhanced survival. This field opens large perspectives not only in tumor biology but also in anti-cancer therapy by targeting one or several steps of the integrin-mediated signaling pathway, including integrin ligation, or activation of integrin-linked enzymes or integrin adaptors.

Chromium III histidinate exposure modulates gene expression in HaCaT human keratinocytes exposed to oxidative stress

While the toxicity of hexavalent chromium is well established, trivalent chromium is an essential nutrient involved in insulin and glucose homeostasis. To study the antioxidant effects of Cr(III)His, cDNA arrays were used to investigate the modulation of gene expression by trivalent chromium histidinate (Cr(III)His) in HaCaT human keratinocytes submitted to hydrogen peroxide (H2O2). Array was composed by a set of 81 expressed sequences tags (ESTs) essentially represented by antioxidant and DNA repair genes. HaCaT were preincubated for 24 h with 50 microM Cr(III)His and were treated with 50 muM H2O2. Total RNAs were isolated immediately or 6 h after the stress. In Cr(III)His preincubated cells, transcripts related to antioxidant family were upregulated (glutathione synthetase, heme oxygenase 2, peroxiredoxin 4). In Cr(III)His preincubated cells and exposed to H2O2, increased expressions of polymerase delta 2 and antioxidant transcripts were observed. Biochemical methods performed in parallel to measure oxidative stress in cells showed that Cr(III)His supplementation before H2O2 stress protected HaCaT from thiol groups decrease and thiobarbituric acid reactive substances increase. In summary, these results give evidence of antioxidant gene expression and antioxidant protection in HaCaT preincubated with Cr(III)His and help to explain the lack of toxicity reported for Cr(III)His.

Aging, depot origin, and preadipocyte gene expression

Fat distribution changes with aging. Inherent changes in fat cell progenitors may contribute because fat cells turn over throughout life. To define mechanisms, gene expression was profiled in preadipocytes cultured from epididymal and perirenal depots of young and old rats. 8.4% of probe sets differed significantly between depots, particularly developmental genes. Only 0.02% differed with aging, despite using less stringent criteria than for comparing depots. Twenty-five genes selected based on fold change with aging were analyzed in preadipocytes from additional young, middle-aged, and old animals by polymerase chain reaction. Thirteen changed significantly with aging, 13 among depots, and 9 with both. Genes involved in inflammation, stress, and differentiation changed with aging, as occurs in fat tissue. Age-related changes were greater in perirenal than epididymal preadipocytes, consistent with larger declines in replication and adipogenesis in perirenal preadipocytes. Thus, age-related changes in preadipocyte gene expression differ among depots, potentially contributing to fat redistribution and dysfunction.

Antigenotoxic and antioxidant activities of isorhamnetin 3-O neohesperidoside from Acacia salicina

Antioxidant activity of isorhamnetin 3-O neohesperidoside (I3ON), isolated from the leaves of Acacia salicina, was determined by the ability of this compound to inhibit lipid peroxidation and to protect against hydroxyl radical-induced DNA damage in pKS plasmid DNA and Escherichia coli cultures. Antigenotoxic activity was assessed by using the comet assay. The IC(50) value of the inhibitory activity toward lipid peroxidation by I3ON is 0.6 mM. This compound was also able to protect against hydroxyl radical-induced DNA damage in pKS plasmid DNA. Moreover, this compound induced an inhibitory activity toward H2O2-induced genotoxicity. The protective effect exhibited by this molecule was also determined by analysis of gene expression as a response to an oxidative stress, using a cDNA microarray. Transcription of several genes related to the antioxidant system (HMOX2 and TXNL) and to the DNA repair pathway (XPC, POLD1, POLD2, PCNA, DDIT3, APEX, and LIG4) were upregulated after incubation with I3ON. Taken together, these observations provide evidence that the I3ON, isolated from the leaves of A. salicina, is able to protect cells against oxidative stress.

Increased age reduces DAF-16 and SKN-1 signaling and the hormetic response of Caenorhabditis elegans to the xenobiotic juglone

Cells adapt to stressors by activating mechanisms that repair damage and protect them from further injury. Stress-induced damage accumulates with age and contributes to age associated diseases. Increased age attenuates the ability to mount a stress response, but little is known about the mechanisms by which this occurs. To begin addressing this problem, we studied hormesis in the nematode Caenorhabditis elegans. When exposed to a low concentration of the xenobiotic juglone, young worms mount a robust hormetic stress response and survive a subsequent exposure to a higher concentration of juglone that is normally lethal to naïve animals. Old worms are unable to mount this adaptive response. Microarray and RNAi analyses demonstrate that an altered transcriptional response to juglone is responsible in part for the reduced adaptation of old worms. Many genes differentially regulated in young versus old animals are known or postulated to be regulated by the FOXO homologue DAF-16 and the Nrf2 homologue SKN-1. Activation of these pathways is greatly reduced in juglone stressed old worms. DAF-16- and SKN-1-like transcription factors play highly conserved roles in regulating stress resistance and longevity genes. Our studies provide a foundation for developing a molecular understanding of how age affects cytoprotective transcriptional pathways.

[Photoaging of face]

The environment, especially solar irradiation, plays a major role in skin aging. In humans, cutaneous areas frequently exposed to solar radiations are subject to premature skin ageing (heliodermatitis) which has specific clinical and histological features distinct from those observed in photoprotected skin. Most of the cellular and molecular mechanisms implicated in chronologic aging are observed in both ultraviolet exposed and photoprotected skin and can be stimulated in vitro and in vivo by repeated ultraviolet exposures. This article reviews the epidemiological, clinical and histological characteristics of photoaging and summarizes the recent findings acquired in this field.

Antimutagenic, antigenotoxic and antioxidant activities of Acacia salicina extracts (ASE) and modulation of cell gene expression by H2O2 and ASE treatment

The total oligomers flavonoids (TOF), chloroform, petroleum ether and aqueous extracts from Acacia salicina, were investigated for the antioxidative, cytotoxic, antimutagenic and antigenotoxic activities. The viability of K562 cells were affected by all extracts after 48 h exposure. Our results showed that A. salicina extracts have antigenotoxic and/or antimutagenic activities. TOF and chloroform extracts exhibit antioxidant properties, expressed by the capacity of these extracts to inhibit xanthine oxidase activity. To further explore the mechanism of action of A. salicina extracts, we characterized expression profiles of genes involved in antioxidant protection and DNA repair in the human lymphoblastic cell line K562 exposed to H2O2. Transcription of several genes related to the thioredoxin antioxidant system and to the DNA base-excision repair pathway was up-regulated after incubation with chloroform, TOF and petroleum ether extracts. Moreover genes involved in the nucleotide-excision repair pathway and genes coding for catalase and Mn-superoxide-dismutase, two important antioxidant enzymes, were induced after incubation with the chloroform extract. Taken together, these observations provide evidence that the chloroform and TOF extracts of A. salicina leaves contain bioactive compounds that are able to protect cells against the consequences of an oxidative stress.

In vitro antioxidant and antigenotoxic potentials of myricetin-3-o-galactoside and myricetin-3-o-rhamnoside from Myrtus communis: modulation of expression of genes involved in cell defence system using cDNA microarray

Antioxidant activity of myricetin-3-o-galactoside and myricetin-3-o-rhamnoside, isolated from the leaves of Myrtus communis, was determined by the ability of each compound to inhibit xanthine oxidase activity, lipid peroxidation and to scavenge the free radical 1,1-diphenyl-2-picrylhydrazyl. Antimutagenic activity was assessed using the SOS chromotest and the Comet assay. The IC50 values of lipid peroxidation by myricetin-3-o-galactoside and myricetin-3-o-rhamnoside are respectively 160 microg/ml and 220 microg/ml. At a concentration of 100 microg/ml, the two compounds showed the most potent inhibitory effect of xanthine oxidase activity by respectively, 57% and 59%. Myricetin-3-o-rhamnoside was a very potent radical scavenger with an IC50 value of 1.4 microg/ml. Moreover, these two compounds induced an inhibitory activity against nifuroxazide, aflatoxine B1 and H2O2 induced mutagenicity. The protective effect exhibited by these molecules was also determined by analysis of gene expression as response to an oxidative stress using a cDNA micro-array. Myricetin-3-o-galactoside and myricetin-3-o-rhamnoside modulated the expression patterns of cellular genes involved in oxidative stress, respectively (GPX1, TXN, AOE372, SEPW1, SHC1) and (TXNRD1, TXN, SOD1 AOE372, SEPW1), in DNA damaging repair, respectively (XPC, LIG4, RPA3, PCNA, DDIT3, POLD1, XRCC5, MPG) and (TDG, PCNA, LIG4, XRCC5, DDIT3, MSH2, ERCC5, RPA3, POLD1), and in apoptosis (PARP).

Transcriptional response of genes involved in cell defense system in human cells stressed by H2O2 and pre-treated with (Tunisian) Rhamnus alaternus extracts: Combination with polyphenolic compounds and classic in vitro assays

The ability of three Rhamnus alaternus leaves extracts on antigenotoxic and gene expression level effects was respectively investigated in a bacterial assay system, i.e. the SOS chromotest with Escherichia coli PQ37 and in human K562 lymphoblast cell line. Total oligomers flavonoids (TOF) enriched, methanol and ethyl acetate extracts were prepared from powdered R. alaternus leaves and characterized quantitatively for the presence of polyphenolic compounds. We explored the response to oxidative stress using the transcriptional profile of genes in K562 cells stressed with H2O2 after incubation with plant extracts. For this purpose, we used a cDNA microarrays containing 82 genes related to cell defense, essentially represented by antioxidant and DNA repair genes. Analysis revealed that SOD1, AOE 372, TXN genes involved in the antioxidant defense system and XPC, LIG4, POLD2, PCNA genes implied in the DNA repair system were among the most expressed ones in the presence of the tested extracts. These results were in accordance with those obtained when we tested the antigenotoxic and antioxidant effects of the same extracts with, respectively the SOS chromotest and the xanthine/xanthine oxidase enzymatic assay system. The effect of the tested extracts on SOS response induced by both Aflatoxin B1 (AFB1: 10 microg/assay) and nifuroxazide (20 microg/assay) showed that the TOF extract exhibited the highest antimutagenic level towards the indirect mutagen AFB1. Whereas ethyl acetate extract showed the highest antimutagenic effect towards the direct mutagen, nifuroxazide. None of the tested extracts induced mutagenic activity. However all the tested extracts exhibited xanthine oxidase inhibiting and superoxide anions scavenging effects. R. alaternus extracts contain compounds with significant antioxidant and antigenotoxic activities. These compounds modulate gene expression as detected by using cDNA arrays.

Study of antimutagenic and antioxidant activities of Gallic acid and 1,2,3,4,6-pentagalloylglucose from Pistacia lentiscus

In vitro antioxidant and antimutagenic activities of two polyphenols isolated from the fruits of Pistacia lentiscus was assessed. Antioxidant activity was determined by the ability of each compound to scavenge the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH*), to inhibit xanthine oxidase and to inhibit the lipid peroxidation induced by H(2)O(2) in K562 cell line. Antimutagenic activity was assayed with SOS chromotest using Escherichia coli PQ37 as tester strain and Comet assay using K562 cell line. 1,2,3,4,6-Pentagalloylglucose was found to be more effective to scavenge DPPH* radical and protect against lipid peroxidation. Moreover, these two compounds induced an inhibitory activity against nifuroxazide and aflatoxin B1 mutagenicity. The protective effect exhibited by these molecules was also determined by analysis of gene expression as response to an oxidative stress. For this purpose, we used a cDNA-microarray containing 82 genes related to cell defense, essentially represented by antioxidant and DNA repair proteins. We found that 1,2,3,4,6-pentagalloylglucose induced a decrease in the expression of 11 transcripts related to antioxidant enzymes family (GPX1, TXN, AOE372, SHC1 and SEPW1) and DNA repair (POLD1, APEX, POLD2, MPG, PARP and XRCC5). The use of Gallic acid, induced expression of TXN, TXNRD1, AOE372, GSS (antioxidant enzymes) and LIG4, POLD2, MPG, GADD45A, PCNA, RPA2, DDIT3, HMOX2, XPA, TDG, ERCC1 and GTF2H1 (DNA repair) as well as the repression of GPX1, SEPW1, POLD1 and SHC1 gene expression.

Systems approaches to the networks of aging

The aging of an organism is the result of complex changes in structure and function of molecules, cells, tissues, and whole body systems. To increase our understanding of how aging works, we have to analyze and integrate quantitative evidence from multiple levels of biological organization. Here, we define a broader conceptual framework for a quantitative, computational systems biology approach to aging. Initially, we consider fractal supply networks that give rise to scaling laws relating body mass, metabolism and lifespan. This approach provides a top-down view of constrained cellular processes. Concomitantly, multi-omics data generation build such a framework from the bottom-up, using modeling strategies to identify key pathways and their physiological capacity. Multiscale spatio-temporal representations finally connect molecular processes with structural organization. As aging manifests on a systems level, it emerges as a highly networked process regulated through feedback loops between levels of biological organization.