Ischemic preconditioning represents the most powerful mechanism of cardioprotection. The mechanisms mediating the second window of preconditioning (SWOP) differ from those mediating first window preconditioning. We hypothesized that chronic ischemia induced by repetitive ischemic stimuli would be mediated by yet different molecular mechanisms. Accordingly, conscious, chronically instrumented pigs (n=5/group) were submitted to a protocol of classical SWOP (two 10-min episodes of coronary artery occlusion followed by 24 hr reperfusion) and compared to pigs submitted to repetitive occlusion/reperfusion (RCO) by repeating 6 episodes of SWOP 12 hrs apart, and to a model of repetitive coronary stenosis (RCS), in which 6 episodes of 90 min coronary stenosis were performed 12 hrs apart. Microarray analysis was performed on the three models. There was an 85% homology in gene response between both models of RCO and RCS, whereas SWOP was qualitatively different. Both models of RCO and RCS but not SWOP showed a down-regulation of genes encoding proteins involved in oxidative metabolism, and an up-regulation of genes involved in protein synthesis and unfolded protein response, autophagy, heat shock response, protein secretion, and a strong activation of the NF-B signaling pathway. Two thirds of the genes regulated in the three models showed a gradual pattern of up- or down-regulation, in which RCO was quantitatively intermediary between RCS and SWOP. Therefore, the regulated genes in response to chronic, repetitive episodes of ischemia differ radically from classical first or second window preconditioning.
Molecular mechanisms mediating preconditioning following chronic ischemia differ from those in classical second window.
Sex, Specimen part
View SamplesThe expression of the small molecular weight heat shock protein (Hsp) H11 kinase/Hsp22 (Hsp22) is restricted to a limited number of tissues, including the heart and skeletal muscle, both in rodents and in humans. We generated a mouse knockout (KO) model, and investigated the role of Hsp22 in regulating cardiac hypertrophy in response to pressure overload. We compared gene expression profiles between WT and KO mice in basal condition and three days pressure overload after transverse aortic constriction (TAC). These data illustrated a novel mechanism of Hsp22-related gene expression in response to cardiac stress.
No associated publication
Sex, Specimen part
View SamplesWe examined how MED23 regulates SRF-targeted genes by comparing WT and Med23 KO mouse embryonic fibroblasts (MEFs) in the presence or absence of serum-stimulation (for 30 and 90 min). To investigate whether MAL antagonizes MED23 in the adipocyte lineage program, we compared the gene expression changes resulting from Mal overexpression (oxMal) and Med23 deficiency (siMed23) in 10T1/2 cell.
Mediator MED23 plays opposing roles in directing smooth muscle cell and adipocyte differentiation.
Specimen part, Treatment
View SamplesCardiac-specific PPARalpha transgenic (Tg-PPARalpha) mice show mild cardiac hypertrophy and systolic dysfunction. The failing heart phenotypes observed in Tg-PPARalpha are exacerbated by crossing with cardiac-specific Sirt1 transgenic (Tg-Sirt1) mice, whereas Tg-Sirt1 mice themselves do not show any cardiac hypertrophy or systolic dysfunction. To investigate the mechanism leading to the failing heart phenotypes in TgPPARalpha/Tg-Sirt1 bigenic mice, microarray analyses were performed. The microarray analyses revealed that many ERR target genes were downregulated in Tg-PPARalpha and in Tg-Sirt1, and they were further downregulated in the Tg-PPARalpha/Tg-Sirt1 bigenic mice.
PPARα-Sirt1 complex mediates cardiac hypertrophy and failure through suppression of the ERR transcriptional pathway.
Sex, Specimen part
View SamplesMuscle atrophy F-box (MAFbx) is an E3 ubiquitin ligase which plays a critical role in mediating skeletal muscle atrophy. We investigated the effect of MAFbx KO in cardiac hypertrophy in response to pressure overload. A DNA microarray analysis was conducted using total RNA prepared from wild type and MAFbx KO mouse hearts subject to transverse aortic constriction (TAC). Results provide insight into the molecular mechanism to mediate the effect of MAFbx upon pathological hypertrophy.
Endogenous muscle atrophy F-box mediates pressure overload-induced cardiac hypertrophy through regulation of nuclear factor-kappaB.
Specimen part
View SamplesThe treatment strategy of rectal cancer has substantially changed in recent decades. Historically postoperative chemoradiotherapy (CRT) was considered to be the first-line therapy for stage II and III rectal cancers. However, the preoperative CRT is now considered to be the optimal therapy regimen for locally advanced rectal ancer due to its improved local control, reduced toxicity, and increased rate of sphincter preservation. Our study established a clinically practical multi-class prediction model by adopting a novel strategy that applies two separate prediction models (MI and TO predictor) sequentially to a patient to predict the response. For promising clinical practice, we validated our model in a published dataset, which is completely independent dataset from ours. This study suggests a clinically plausible prediction model that correctly infers the preoperative CRT response of patients with high accuracy based on 163 gene signatures we identified.
No associated publication
Sex, Age
View SamplesDrug-induced alterations in transcriptional regulation play a central role in establishing the persistent neuroplasticities that occur during drug addiction. Additionally, changes in gene expression associated with drug administration provide valuable insight into the molecular basis of drug abuse. The molecular mechanisms that underlie susceptibility to psychostimulant addiction remain unknown. Identifying the common gene transcriptional responses to psychostimulants can provide a mechanistic insight to elucidate the molecular nature of drug dependence.
Neuronal development genes are key elements mediating the reinforcing effects of methamphetamine, amphetamine, and methylphenidate.
Specimen part
View SamplesTo identify a set of genes related to radioresistance, we analyzed the time-series gene expression profiles of radioresistant H1299 and radiosensitive H460 lung cancer cells in response to 2 Gy of ionizing radiation (IR) by performing quadratic regression (QR) analysis. Out of the 21,331 genes, we selected 6,538 genes by QR analysis from the gene expression profile of H460 cells and 6,086 genes from that of H1299 cells. Most of the genes identified in the H460 cells were classified into continuously up- or down-regulated groups, while the major QR groups were transiently changed groups in the H1299 cell line. From gene ontology analysis of the major QR groups, the DNA damage response was commonly enriched in both cell lines. DNA repair-related genes such as ATM, ATR, TP53BP1, BRCA1, MRE11, NBN and RAD50 were particularly up-regulated in H1299 cells. Suppression of these DNA repair-related genes using siRNA made H1299 cells radiosensitive to ionizing radiation. The data suggest that differential responses to DNA damage confer radioresistance to cancer cells, and provide potential novel targets for sensitizing radiotherapy.
No associated publication
Cell line
View SamplesPediatric medulloblastoma is considered a highly heterogeneous disease, and a new strategy of risk stratification to optimize therapeutic outcomes is required. We aimed to investigate a new risk-stratification approach based on expression profiles of medulloblastoma cohorts. We analyzed gene expression profiles of 30 primary medulloblastomas and detected strong evidence that poor survival outcome was significantly associated with mRNA expression profiles of 17p loss. However, it was not supported in independent cohorts from previously published data (n=100). We speculated that this controversy might come from complex conditions of two important prognostic determinants, loss of tumor suppressors (chromosome 17p) and high expression of oncogenes, c-myc (MYC) or N-myc (MYCN). Simultaneous consideration of these two factors led to a new subgrouping of patients, exhibiting obviously different survival expectancies between the subgroups. Patients with up-regulated WNT signalings were always pre-defined as an independent subgroup, which ultimately removed confounding effect arising from contradictory outcome, favorable prognosis of WNT medulloblastomas despite their high MYC/MYCN expression level. We also found that age is a significant prognostic marker after adjusting for 17p and MYC/MYCN status. Diminished survival in age <3 years was more substantial in groups with high expression of MYC/MYCN or 17p loss, indicating survival outcome might be coordinately affected by these three factors. We suggest a more tailored and easily applicable subgrouping system based on expression profiles of chromosome 17p and MYC/MYCN, while separating WNT medulloblastoma as an independent subgroup, which could provide the basis for a novel risk-stratification strategy in pediatric medulloblastoma.
Prognostic classification of pediatric medulloblastoma based on chromosome 17p loss, expression of MYCC and MYCN, and Wnt pathway activation.
Sex, Specimen part
View SamplesWe focused on whether transposon mutagenesis in Brucella abortus could induce difference in the trascriptional responses of RAW 264.7 cell infection model compared to the wild strain infected RAW 264.7 cells.
No associated publication
Cell line, Time
View Samples