A simple stochastic model for the feedback circuit between p16INK4a and p53 mediated by p38MAPK: implications for senescence and apoptosis

The network pharmacology study and molecular docking to investigate the potential mechanism of Acoritataninowii Rhizoma against Alzheimer's Disease

Alzheimer's Disease is considered as an insidious neurodegenerative progressive disease but its pathogenesis has not been elucidated. Acoritataninowii Rhizoma exhibits anti-dementia effects as a traditional Chinese medicine (TCM), which is linked to its anti- Alzheimer's Disease mechanism. In this study, network pharmacology and molecular docking were used to examine the potential of Acoritataninowii Rhizoma for Alzheimer's Disease. In order to construct PPI networks and drug-component-target-disease networks, disease-related genes and proteins were gathered from the database. Gene ontology (GO), pathway enrichment (KEGG), and molecular docking were used to forecast the potential mechanism of Acoritataninowii Rhizoma on Alzheimer's disease. Therefore, 4 active ingredients and 81 target genes were screened from Acoritataninowii Rhizoma, 6765 specific target genes were screened from Alzheimer's Disease, and 61 drug-disease cross genes were validated. GO analysis showed that Acoritataninowii Rhizoma can regulate processes such as the protein serine/threonine kinase associated with MAPK. KeGG pathway analysis showed that the signaling pathways affected by Acoritataninowii Rhizoma were fluid shear stress and atherosclerosis, AGE-RAGE and other pathways. Molecular docking implied that the pharmacological influences of the bioactive constituents of Acoritataninowii Rhizoma (Cycloaartenol and kaempferol) on Alzheimer's Disease may related to ESR1 and AKT1, respectively. AKT1 and ESR1 may be the core target genes of the treatment for Alzheimer's disease. Kaempferol and Cycloartenol might be core bioactive constituents for treatment.

Candesartan Neuroprotection in Rat Primary Neurons Negatively Correlates with Aging and Senescence: a Transcriptomic Analysis

Preclinical experiments and clinical trials demonstrated that angiotensin II AT₁ receptor overactivity associates with aging and cellular senescence and that AT₁ receptor blockers (ARBs) protect from age-related brain disorders. In a primary neuronal culture submitted to glutamate excitotoxicity, gene set enrichment analysis (GSEA) revealed expression of several hundred genes altered by glutamate and normalized by candesartan correlated with changes in expression in Alzheimer's patient's hippocampus. To further establish whether our data correlated with gene expression alterations associated with aging and senescence, we compared our global transcriptional data with additional published datasets, including alterations in gene expression in the neocortex and cerebellum of old mice, human frontal cortex after age of 40, gene alterations in the Werner syndrome, rodent caloric restriction, Ras and oncogene-induced senescence in fibroblasts, and to tissues besides the brain such as the muscle and kidney. The most significant and enriched pathways associated with aging and senescence were positively correlated with alterations in gene expression in glutamate-injured neurons and, conversely, negatively correlated when the injured neurons were treated with candesartan. Our results involve multiple genes and pathways, including CAV1, CCND1, CDKN1A, CHEK1, ICAM1, IL-1B, IL-6, MAPK14, PTGS2, SERPINE1, and TP53, encoding proteins associated with aging and senescence hallmarks, such as inflammation, oxidative stress, cell cycle and mitochondrial function alterations, insulin resistance, genomic instability including telomere shortening and DNA damage, and the senescent-associated secretory phenotype. Our results demonstrate that AT₁ receptor blockade ameliorates central mechanisms of aging and senescence. Using ARBs for prevention and treatment of age-related disorders has important translational value.

The potential mechanism of extracellular high mobility group box-1 protein mediated p53 expression in immune dysfunction of T lymphocytes

In the present study, we examined the activity of p53 protein in Jurkat cells treated with high mobility group box-1 protein (HMGB1), thereafter we investigated the mechanism of extracellular HMGB1 mediated p53 expression in immune dysfunction of T lymphocytes. mRNA expression of p53, mdm2, and p21 was determined by Real-time reverse transcription-polymerase chain reaction(RT-PCR). The apoptotic rate of Jurkat cells was analyzed by flow cytometry. Expressions of bcl-2, bax, caspase-3, phosphorylated (p) extracellular signal-regulated kinase (ERK)1/2, ERK1/2, p-p38 mitogen-activated protein kinase (MAPK), p38 MAPK, and p-c-jun amino-terminal kinase (JNK)1/2 and JNK1/2 were simultaneously determined by Western blotting. After treatment with HMGB1 (100 ng/ml or 1000 ng/ml), the proliferative activity of Jurkat cells was significantly decreased, and a low and medium concentration of HMGB1 induced an up-regulation of p53 mRNA, p-p53 and p53 protein expression. Meanwhile, levels of mdm2 and p21 were elevated by incubated with HMGB1 (100 ng/ml) for 24 or 48 hours. Moreover, the proliferation of Jurkat cells in response to HMGB1 (100 ng/ml) in the vector group was significantly depressed. The bax and caspase-3 levels in p53 shRNA-expressed cells treated with HMGB1 (100 ng/ml) was markedly decreased, whereas expression of bcl-2 was obviously enhanced. Among ERK1/2, p38 MAPK and JNK1/2 signaling, only p38 MAPK pathway could be significantly activated by treatment with HMGB1, and the specific inhibitor of p38 MAPK was used, p53 and p-p53 expression induced by HMGB1 were significantly down-regulated. Taken together, our data strongly indicated that HMGB1 might enhance p53 expression, which was associated with both the proliferative activity as well as apoptosis of T cells.

MicroRNA-16 feedback loop with p53 and Wip1 can regulate cell fate determination between apoptosis and senescence in DNA damage response

Cell fate regulation is an open problem whose comprehension impacts several areas of the biosciences. DNA damage induces cell cycle checkpoints that activate the p53 pathway to regulate cell fate mechanisms such as apoptosis or senescence. Experiments with different cell types show that the p53 pathway regulates cell fate through a switch behavior in its dynamics. For low DNA damage the pathway presents an oscillatory pattern associated with intense DNA damage repair while for high damage there are no oscillations and either p53 concentration increases inducing apoptosis or the cell enters a senescence state. Apoptosis and senescence phenotypes seem to have compensatory functions in tissues and the microRNA 16-1 (miR-16) is involved in the regulation of the fate between both phenotypes in cancer cells. To investigate the regulation of cell fate we developed a logical model of the G1/S checkpoint in DNA damage response that takes into account different levels of damage and contemplates the influence of miR-16 through its positive feedback loop formed with p53 and Wip1. The model reproduces the observed cellular phenotypes in experiments: oscillatory (for low DNA damage) regulated by negative feedback loops involving mainly p53 and Mdm2 and apoptotic or senescent (for high DNA damage) regulated by the positive p53/Wip1/miR-16 feedback loop. We find good agreement between the level of DNA damage and the probability of the phenotype produced according to experiments. We also find that this positive feedback makes senescent and apoptotic phenotypes to be determined stochastically (bistable), however controlling the expression level of miR-16 allows the control of fate determination as observed experimentally.

Immunosenescence Induced by Plasma from Individuals with Obesity Caused Cell Signaling Dysfunction and Inflammation

OBJECTIVE

To evaluate the consequences of plasma from individuals with obesity on parameters associated with immunosenescence in unrelated healthy peripheral blood mononuclear cells (PBMC).

METHODS

Freshly isolated PBMC were incubated in media supplemented with 10% of plasma from individuals with obesity or control subjects for the first 4 hours of 24 to 120 hours of culture.

RESULTS

Plasma from individuals with obesity modulated the phenotype of healthy PBMC, leading to a higher rate of apoptosis, lower amounts of phospho-γH2AX and -p53, and mitochondrial dysfunction. After 120 hours, there was a higher secretion of inflammatory cytokines IL-1β and IL-8. CD8⁺ T lymphocytes presented decreased expression of CD28, which is associated with the immunosenescent phenotype. CD14⁺ macrophages showed increased expression of CD80 and CD206, suggesting a modulation in the activation of macrophages.

CONCLUSIONS

These results demonstrate that chronic systemic inflammation observed in obesity induces dysfunctional features in PBMC that are consistent with premature immunosenescence.