The accumulation of irreparable cellular damage restricts healthy lifespan after acute stress or natural aging. Senescent cells are thought to impair tissue function and their genetic clearance can successfully delay features of aging. Identifying how senescent cells avoid apoptosis would allow for the prospective design of anti-senescence compounds to address whether homeostasis can be restored. Here, we identify FOXO4 as a pivot in the maintenance of senescent cell viability. We designed a FOXO4-based peptide which selectively competes for interaction of FOXO4 with p53. In senescent cells, this results in p53 nuclear exclusion and cell-intrinsic apoptosis. Importantly, under conditions where it was well tolerated, the FOXO4 peptide restored liver function after Doxorubicin-induced chemotoxicity. Moreover, in fast aging XpdTTD/TTD, as well as in naturally aged mice the FOXO4 peptide could counteract the loss of fitness, fur density and renal function. Thus, it is possible to therapeutically target senescent cells and thereby effectively counteract senescence-associated loss of tissue homeostasis. Overall design: mRNA expression levels are compared between IR-induced senescent and proliferating IMR90 cells in triplicate
Targeted Apoptosis of Senescent Cells Restores Tissue Homeostasis in Response to Chemotoxicity and Aging.
Specimen part, Cell line, Subject
View SamplesMedium-chain acyl-coenzyme A (CoA) dehydrogenase (MCAD) catalyzes crucial steps in mitochondrial fatty acid oxidation, a process that is of key relevance for maintenance of energy homeostasis, especially during high metabolic demand. To gain insight into the metabolic consequences of MCAD deficiency under these conditions, we compared hepatic carbohydrate metabolism in vivo in wild-type and MCAD-/- mice during fasting and during a lipopolysaccharide (LPS)-induced acute phase response (APR). MCAD-/- mice did not become more hypoglycemic on fasting or during the APR than wild-type mice did. Nevertheless, microarray analyses revealed increased hepatic peroxisome proliferator-activated receptor gamma coactivator-1a (Pgc-1a) and decreased peroxisome proliferator-activated receptor alpha (Ppar a) and pyruvate dehydrogenase kinase 4 (Pdk4) expression in MCAD-/- mice in both conditions,suggesting altered control of hepatic glucose metabolism. Quantitative flux measurements revealed that the de novo synthesis of glucose-6-phosphate (G6P) was not affected on fasting in MCAD-/- mice. During the APR, however, this flux was significantly decreased (-20%) in MCAD-/- mice compared with wild-type mice. Remarkably, newly formed G6P was preferentially directed toward glycogen in MCAD-/- mice under both conditions. Together with diminished de novo synthesis of G6P, this led to a decreased hepatic glucose output during the APR in MCAD-/- mice; de novo synthesis of G6P and hepatic glucose output were maintained in wild-type mice under both conditions. APR-associated hypoglycemia, which was observed in wild-type mice as well as MCAD-/- mice, was mainly due to enhanced peripheral glucose uptake. Conclusion: Our data demonstrate that MCAD deficiency in mice leads to specific changes in hepatic carbohydrate management on exposure to metabolic stress. This deficiency, however, does not lead to reduced de novo synthesis of G6P during fasting alone, which may be due to the existence of compensatory mechanisms or limited rate control of MCAD in murine mitochondrial fatty acid oxidation.
Disturbed hepatic carbohydrate management during high metabolic demand in medium-chain acyl-CoA dehydrogenase (MCAD)-deficient mice.
Sex, Specimen part, Treatment
View SamplesThe underlying relation between Parkinson disease (PD) etiopathology and its major risk factor, aging, is largely unknown. The nature of the specific age-related mechanisms promoting PD onset is experimentally difficult to elucidate because aging is a highly complex process contributed by multiple factors. Recent evidence, however, established a strong and causative link between genome stability and aging. To investigate a possible nexus between DNA damage accumulation, aging, and PD we examined DNA repair pathways associated with aging in laboratory animal models and human cases. We demonstrate that dermal fibroblasts from PD patients display flawed nucleotide excision repair (NER) capacity and that NER-defective mice exhibit typical PD-like pathological alterations, including decreased dopaminergic innervation in the striatum, increased phospho-synuclein levels, and defects in mitochondrial respiration. NER mouse mutants are also more sensitive to the prototypical PD toxin MPTP and their transcriptomic landscape shares important similarities with that of PD patients. Overall, our results demonstrate that specific defects in DNA repair impact the dopaminergic system, are associated with human PD pathology, and might therefore constitute a novel risk factor for PD by affecting the aging process. Overall design: In total 8 samples were analyzed, 4 controls and 4 Ercc1 mutants.
Inefficient DNA Repair Is an Aging-Related Modifier of Parkinson's Disease.
Specimen part, Cell line, Subject
View SamplesChronic Lymphocytic Leukemia (CLL) cells multiply in secondary lymphoid tissue but the mechanisms leading to their proliferation are still uncertain. In addition to BCR-triggered signals, other microenvironmental factors might well be involved. In proliferation centres, leukemic B cells are in close contact with CD4+CD40L+T cells. Therefore, we here dissected the signals provided by autologous activated T cells (Tact) to CLL cells. Although the gene expression profile induced by Tact was highly similar to that induced by sole CD40 signaling, an obvious difference was that Tact induced proliferation of CLL cells. We determined that stimulation with only CD40L+IL-21 was sufficient to induce robust proliferation in CLL cells. We then defined an IL-21-induced gene signature in CLL, containing components of JAK-STAT and apoptosis pathways, and this signature could be detected in lymph node (LN) samples from patients. Finally, we could detect IL-21 RNA and protein in LN, and IL-21 productionex vivoby LN CD4+CXCR5+ follicular helper T cells. These results indicate that, in addition to BCR signaling, activated T cells might contribute to CLL cell proliferation via CD40 and IL-21. Targeting these signaling pathways might offer new venues for treatment of CLL.
IL-21 and CD40L signals from autologous T cells can induce antigen-independent proliferation of CLL cells.
Specimen part, Treatment
View SamplesNave, liver- and gut-activated CD8 OT-I T cells show differential migration behaviour. To analyze which genes could be responsible for different migration patterns, nave, liver-activated and gut-activated CD8 T cells were isolated and compared for their gene expression profile.
Influence of CD8 T cell priming in liver and gut on the enterohepatic circulation.
Sex, Specimen part
View SamplesAffymetrix microarray data was generated from MCF7 breast cancer cells treated in vitro with siRNAs against 78 transcription factors and signalling molecules.
Cell cycle gene networks are associated with melanoma prognosis.
Cell line
View SamplesAffymetrix microarray data were generated from A375 melanoma cells treated in vitro with siRNAs against 45 transcription factors and signalling molecules.
Cell cycle gene networks are associated with melanoma prognosis.
Cell line
View SamplesA collection of genetically engineered mouse models (GEMM) of colorectal cancer (CRC) were created, and primary tumors from these GEMMs were analyzed.
Cross-species analysis of genetically engineered mouse models of MAPK-driven colorectal cancer identifies hallmarks of the human disease.
Specimen part
View SamplesPrevious studies have reported that the tumour cells of nasopharyngeal carcinoma (NPC) exhibit both recurrent chromosome abnormalities and changes in the expression of numerous genes. However, it is not known to what extent changes in the copy number of individual genes are associated with the observed expression changes. To address this, a genome wide analysis of chromosome copy number and gene expression was performed in tumour cells micro-dissected from the same NPC biopsies. Significant gene expression changes were identified in tumour suppressor genes (TSGs) and in tumour-promoting genes (TPGs) but almost 60% of these can be either upregulated or downregulated in different types of cancer. This suggests that the simplistic classification of genes as TSGs or TPGs may not be entirely appropriate and that the concept of onco-suppressors may be more extensive than previously recognised. Several genomic regions showing frequent copy number gain or loss were identified. Whereas TSGs were significantly enriched within regions of frequent loss, no significant enrichment of TPGs was observed in regions of frequent gain. However, on a gene by gene basis little correlation was found between DNA copy number and alterations in gene expression except for loss of expression from homozygous deletions and a single highly amplified segment which showed enhanced gene expression.
A global view of the oncogenic landscape in nasopharyngeal carcinoma: an integrated analysis at the genetic and expression levels.
Disease, Disease stage
View SamplesPersons with Down syndrome (DS) exhibit low muscle strength that significantly impairs their physical functioning. The Ts65Dn mouse model of DS also exhibits muscle weakness in vivo and may serve as a useful model to examine potential factors responsible for DS-associated muscle dysfunction. Therefore, the purpose of this experiment was to directly assess skeletal muscle function in the Ts65Dn mouse and to reveal potential mechanisms of DS-associated muscle weakness. Soleus muscles were harvested from anesthetized male Ts65Dn and wild-type (WT) colony controls. In vitro muscle contractile experiments revealed normal force generation of unfatigued Ts65Dn soleus, but a 12% reduction in force was observed in Ts65Dn muscle during recovery following fatiguing contractions compared to WT muscle (p<0.05). Oxidative stress may contribute to DS-related pathologies, including muscle weakness, which may be the result of overexpression of chromosome 21 genes (e.g., copper-zinc superoxide dismutase (SOD1)). SOD1 expression was 25% higher (p<0.05) in Ts65Dn soleus compared to WT muscle but levels of other antioxidant proteins were unchanged. Lipid peroxidation (4-hydroxynoneal) was unaltered in Ts65Dn muscle although protein carbonyls were 20% greater compared to muscle of WT animals (p<0.05). Cytochrome c oxidase expression was reduced 22% in Ts65Dn muscle, suggesting a limitation in mitochondrial function may contribute to post-fatigue muscle weakness. Microarray analysis of Ts65Dn soleus revealed alteration of numerous cellular pathways including: proteolysis, glucose and fat metabolism, neuromuscular transmission, and ATP biosynthesis. In summary, the Ts65Dn mouse displays evidence of muscle dysfunction, and the potential role of mitochondria and oxidative stress warrants further investigation.
Functional and biochemical characterization of soleus muscle in Down syndrome mice: insight into the muscle dysfunction seen in the human condition.
Sex, Age, Specimen part
View Samples