Jun Gu

Regulation of TNF Expression by Multiple Mitogen-Activated Protein Kinase Pathways

Stimulating macrophages with bacterial endotoxin (LPS) activates numerous intracellular signaling pathways that lead to the production of TNF. In this study, we show that four mitogen-activated protein (MAP) kinase pathways are activated in LPS-stimulated macrophages: the extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase/stress-activated protein kinase, p38, and Big MAP kinase (BMK)/ERK5 pathways. Although specific activation of a single MAP kinase pathway produces only a modest effect on TNF promoter activation, activation of each MAP kinase pathway is important for full induction of the TNF gene. Interestingly, a dramatic induction of TNF promoter-driven gene expression was observed when all of the four MAP kinase pathways were activated simultaneously, suggesting a cooperative effect among these kinases. Unexpectedly, cis elements known to be targeted by MAP kinases do not play a major role in multiple MAP kinase-induced TNF gene expression. Rather, a 40-bp sequence harboring the TATA box, is responsible for the gene up-regulation induced by MAP kinases. The proximity of the MAP kinase-responsive element to the transcriptional initiation site suggested that MAP kinases regulate the transcriptional initiation complex. Utilizing α-amanitin-resistant RNA polymerase II mutants with or without a C-terminal domain (CTD) deletion, we found that deleting the CTD to 31 tandem repeats (Δ31) led to >90% reduction in MAP kinase-mediated TNF production. Thus, our data demonstrate coordination of multiple MAP kinase pathways in TNF production and suggest that the CTD of RNA polymerase II is required to execute MAP kinase signaling in TNF expression.

NuRD blocks reprogramming of mouse somatic cells into Pluripotent stem cells

Reprogramming of somatic cells into induced pluripotent stem cells (iPSCs) by overexpression of a defined set of transcription factors requires epigenetic changes in pluripotency genes. Nuclear reprogramming is an inefficient process and the molecular mechanisms that reset the epigenetic state during iPSC generation are largely unknown. Here, we show that downregulation of the nucleosome remodeling and deacetylation (NuRD) complex is required for efficient reprogramming. Overexpression of Mbd3, a subunit of NuRD, inhibits induction of iPSCs by establishing heterochromatic features and silencing embryonic stem cell‐specific marker genes, including Oct4 and Nanog. Depletion of Mbd3, on the other hand, improves reprogramming efficiency and facilitates the formation of pluripotent stem cells that are capable of generating viable chimeric mice, even in the absence of c‐Myc or Sox2. The results establish Mbd3/NuRD as an important epigenetic regulator that restricts the expression of key pluripotency genes, suggesting that drug‐induced downregulation of Mbd3/NuRD may be a powerful means to improve the efficiency and fidelity of reprogramming. STEM Cells2013;31:1278–1286

Novel loci and pathways significantly associated with longevity.

Only two genome-wide significant loci associated with longevity have been identified so far, probably because of insufficient sample sizes of centenarians, whose genomes may harbor genetic variants associated with health and longevity. Here we report a genome-wide association study (GWAS) of Han Chinese with a sample size 2.7 times the largest previously published GWAS on centenarians. We identified 11 independent loci associated with longevity replicated in Southern-Northern regions of China, including two novel loci (rs2069837-IL6; rs2440012-ANKRD20A9P) with genome-wide significance and the rest with suggestive significance (Pu2009<u20093.65u2009×u200910−5). Eight independent SNPs overlapped across Han Chinese, European and U.S. populations, and APOE and 5q33.3 were replicated as longevity loci. Integrated analysis indicates four pathways (starch, sucrose and xenobiotic metabolism; immune response and inflammation; MAPK; calcium signaling) highly associated with longevity (Pu2009≤u20090.006) in Han Chinese. The association with longevity of three of these four pathways (MAPK; immunity; calcium signaling) is supported by findings in other human cohorts. Our novel finding on the association of starch, sucrose and xenobiotic metabolism pathway with longevity is consistent with the previous results from Drosophilia. This study suggests protective mechanisms including immunity and nutrient metabolism and their interactions with environmental stress play key roles in human longevity.

GxE Interactions between FOXO Genotypes and Tea Drinking Are Significantly Associated with Cognitive Disability at Advanced Ages in China

Logistic regression analysis based on data from 822 Han Chinese oldest old aged 92+ demonstrated that interactions between carrying FOXO1A-266 or FOXO3-310 or FOXO3-292 and tea drinking at around age 60 or at present time were significantly associated with lower risk of cognitive disability at advanced ages. Associations between tea drinking and reduced cognitive disability were much stronger among carriers of the genotypes of FOXO1A-266 or FOXO3-310 or FOXO3-292 compared with noncarriers, and it was reconfirmed by analysis of three-way interactions across FOXO genotypes, tea drinking at around age 60, and at present time. Based on prior findings from animal and human cell models, we postulate that intake of tea compounds may activate FOXO gene expression, which in turn may positively affect cognitive function in the oldest old population. Our empirical findings imply that the health benefits of particular nutritional interventions, including tea drinking, may, in part, depend upon individual genetic profiles.

CHD4/NuRD maintains demethylation state of rDNA promoters through inhibiting the expression of the rDNA methyltransferase recruiter TIP5

Despite the well-established fact that NuRD (nucleosome remodeling and histone deacetylase) is incapable of actively demethylating DNA, the complex is surprisingly showed to be required for the establishment of unmethylated state at promoters of ribosomal genes. But the molecular mechanism underlying how NuRD mediates unmethylation at rDNA promoters remains obscure. Here we show that NuRD directly binds to the promoter of rDNA transcription silencer TIP5 (TTF-I interacting protein 5), one of the components of nucleolar remodeling complex NoRC that silences rRNA genes by recruiting DNA methyltransferase to rDNA promoters and increasing DNA methylation. NuRD negatively regulates TIP5 expression, thereby inhibiting rDNA methylation and maintaining demethylation state of rDNA promoters. The deficiency of NuRD components in reprogrammed cells activates TIP5 expression, resulting in the increased fraction of heterochromatic rRNA genes and transcriptional silencing. Thus, NuRD is able to control methylation status of rDNA promoters through crosstalking with NoRC complex.

Health Consequences of Familial Longevity Influence Among the Chinese Elderly

BACKGROUNDnA comparative analysis between centenarians children and neighborhood controls is an efficient approach to learn how familial longevity influence and its interaction with environmental factors affect healthy aging. Yet, there are few extant studies that inform this topic; this study expands this literature.nnnMETHODSnWe analyze data from 417 children of centenarians and 560 neighborhood controls without family history of longevity in China (all participants aged 60-80) using ordered logit regression models.nnnRESULTSnWe found that, compared to the neighborhood controls and adjusted for various potentially confounding factors, centenarians children had significantly better instrumental activities of daily living function(p < .001), smaller number of chronic conditions or health problems(p < .01), less anxiety and loneliness(p < .01), better cognitive function (p < .01), more resilience (p < .01), better self-rated health (p < .001), and better self-rated life satisfaction (p < .001). The results also reveal that interactions between familial longevity influence and one of three environmental factors (whether, as children, they received adequate medical care when ill, number of living children, and household economic conditions) may possibly affect health outcomes at old ages (p < .05). We discovered that effects of the environmental factors on health outcome are substantially stronger among elders who have no family history of longevity compared to centenarians children who probably carry positive genes and/or lifestyle behaviors from their long-lived parent(s), which may promote longevity.nnnCONCLUSIONnFamilial longevity influence, through genetics and family lifestyle, is significantly associated with various aspects of health at older ages. Interactions between familial longevity influence and some environmental factors may affect health in old age.

Nuclear protein NP60 regulates p38 MAPK activity

The activation of p38α is mediated by its upstream kinase and associated proteins. Here we identify a new nuclear protein, NP60, which regulates the activation of p38α in response to sorbitol treatment. NP60 specifically binds to p38α, but not to JNK and ERK, in vitro and in vivo. Co-transfection of NP60 leads to the phosphorylation and activation of p38α, and subsequently results in the phosphorylation and activation of activating transcription factor 2. The phosphorylation of p38α induced by NP60 requires upstream activity of p38α MAP kinase, MAP kinase kinase 6 (MKK6) or MKK4. Our results indicate that NP60 mediates stress activation of p38α and regulates p38α signaling in a specific way.

Interactions between Social/ behavioral factors and ADRB2 genotypes may be associated with health at advanced ages in China

BackgroundExisting literature indicates that ADRB2 gene is associated with health and longevity, but none of previous studies investigated associations of carrying the ADRB2 minor alleles and interactions between ADRB2 genotypes and social/behavioral factors(GxE) with health outcomes at advanced ages. This study intends to fill in this research gap.MethodWe conducted an exploratory analysis, using longitudinal survey phenotype/genotype data from 877 oldest-old aged 90+. To estimate association of GxE interactions with health outcome, adjusted for the potential correlation between genotypes and social/behavioral factors and various other potentially confounding factors, we develop and test an innovative three-step procedure which combines logistic regression and structural equation methods.ResultsInteraction between regular exercise and carrying rs1042718 minor allele is significantly and positively associated with good cognitive function; interaction between regular exercise and carrying rs1042718 or rs1042719 minor allele is significantly and positively associated with self-reported good health; and interaction between social-leisure activities and carrying rs1042719 minor allele is significantly and positively associated with self-reported good health. Carrying rs1042718 or rs1042719 minor alleles is significantly and negatively associated with negative emotion, but the ADRB2 SNPs are not significantly associated with cognitive function and self-reported health. Our structural equation analysis found that, adjusted for the confounding effects of correlation of the ADRB2 SNPs with negative emotion, interaction between negative emotion and carrying rs1042718 or rs1042719 minor allele is significantly and negatively associated with cognitive function. The positive association of regular exercise and social-leisure activities with cognitive function and self-reported health, and negative association of negative emotion with cognitive function, were much stronger among carriers of rs1042718 or rs1042719 alleles, compared to the non-carriers.ConclusionsThe results indicate significant positive associations of interactions between social/behavioral factors and the ADRB2 genotypes with health outcomes of cognitive function and self-reported health, and negative associations of carrying rs1042718 or rs1042719 minor alleles with negative emotion, at advanced ages in China. Our findings are exploratory rather than causal conclusions. This study implies that near-future health promotion programs considering individuals’ genetic profiles, with appropriate protection of privacy/confidentiality, would yield increased benefits and reduced costs to the programs and their participants.

GxE interactions between FOXO genotypes and drinking tea are significantly associated with prevention of cognitive decline in advanced age in China.

Logistic regression analysis based on data from 822 Han Chinese oldest old aged 92+ demonstrated that interactions between carrying FOXO1A-266 or FOXO3-310 or FOXO3-292 and tea drinking at around age 60 or at present time were significantly associated with lower risk of cognitive disability at advanced ages. Associations between tea drinking and reduced cognitive disability were much stronger among carriers of the genotypes of FOXO1A-266 or FOXO3-310 or FOXO3-292 compared with noncarriers, and it was reconfirmed by analysis of three-way interactions across FOXO genotypes, tea drinking at around age 60, and at present time. Based on prior findings from animal and human cell models, we postulate that intake of tea compounds may activate FOXO gene expression, which in turn may positively affect cognitive function in the oldest old population. Our empirical findings imply that the health benefits of particular nutritional interventions, including tea drinking, may, in part, depend upon individual genetic profiles.

The binding of actin to p38 MAPK and inhibiting its kinase activity in vitro.

Abstractp38 MAP kinase mediates a signal pathway that is involved in many physiological and pathological processes such as inflammation, cellular stress, apoptosis, cell cycle and growth, ischemia/re-perfusion, and myocardium hypertrophy. To determine the molecular and regulative mechanism of p38 signal pathway, we usedin vitro binding methods to screen the proteins that interact with p38. Here we report two proteins from mouse macrophage RAW264.7 strain treated with lipopolysaccharide (LPS) or ultraviolet radiation (UV), binding directly to p38. One of them is β-actin identified by peptide mass spectrum and ProFound program. Actin can inhibit the autophosphorylation of p38 and the phosphorylation of ATF by p38. It suggests that the binding of actin to p38in vitro may represent a negative feedback to the kinase activity of p38, which leads to the regulation of p38 pathway and cellular function.