Negative Elongation Factor Controls Energy Homeostasis in Cardiomyocytes

SummaryNegative elongation factor (NELF) is known to enforce promoter-proximal pausing of RNA polymerase II (Pol II), a pervasive phenomenon observed across multicellular genomes. However, the physiological impact of NELF on tissue homeostasis remains unclear. Here, we show that whole-body conditional deletion of the B subunit of NELF (NELF-B) in adult mice results in cardiomyopathy and impaired response to cardiac stress. Tissue-specific knockout of NELF-B confirms its cell-autonomous function in cardiomyocytes. NELF directly supports transcription of those genes encoding rate-limiting enzymes in fatty acid oxidation (FAO) and the tricarboxylic acid (TCA) cycle. NELF also shares extensively transcriptional target genes with peroxisome proliferator-activated receptor α (PPARα), a master regulator of energy metabolism in the myocardium. Mechanistically, NELF helps stabilize the transcription initiation complex at the metabolism-related genes. Our findings strongly indicate that NELF is part of the PPARα-mediated transcription regulatory network that maintains metabolic homeostasis in cardiomyocytes

Genes implicated in multiple sclerosis pathogenesis from consilience of genotyping and expression profiles in relapse and remission

<p>Abstract</p> <p>Background</p> <p>Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS). Although the pathogenesis of MS remains unknown, it is widely regarded as an autoimmune disease mediated by T-lymphocytes directed against myelin proteins and/or other oligodendrocyte epitopes.</p> <p>Methods</p> <p>In this study we investigated the gene expression profiles of peripheral blood cells from patients with RRMS during the relapse and the remission phases utilizing gene microarray technology. Dysregulated genes encoded in regions associated with MS susceptibility from genomic screens or previous trancriptomic studies were identified. The proximal promoter region polymorphisms of two genes were tested for association with disease and expression level.</p> <p>Results</p> <p>Distinct sets of dysregulated genes during the relapse and remission phases were identified including genes involved in apoptosis and inflammation. Three of these dysregulated genes have been previously implicated with MS susceptibility in genomic screens: TGFβ1, CD58 and DBC1. TGFβ1 has one common SNP in the proximal promoter: -508 T>C (rs1800469). Genotyping two Australian trio sets (total 620 families) found a trend for over-transmission of the T allele in MS in females (p < 0.13). Upregulation of CD58 and DBC1 in remission is consistent with their putative roles in promoting regulatory T cells and reducing cell proliferation, respectively. A fourth gene, ALOX5, is consistently found over-expressed in MS. Two common genetic variants were confirmed in the ALOX5 putatve promoter: -557 T>C (rs12762303) and a 6 bp tandem repeat polymorphism (GGGCGG) between position -147 and -176; but no evidence for transmission distortion found.</p> <p>Conclusion</p> <p>The dysregulation of these genes tags their metabolic pathways for further investigation for potential therapeutic intervention.</p

RNA polymerase II large subunit degradation induced by ecteinascidin 743: Molecular characterization and subsequent rational investigation of antitumor mechanisms in cancers with clinical response

Ecteinascidin 743 (Et-743), which is a novel DNA minor groove alkylator with a unique spectrum of antitumor activity, is currently being evaluated in phase II/III clinical trials. Although the precise molecular mechanisms responsible for the observed antitumor activity are poorly understood, recent data suggests that post-translational modifications of RNA polymerase II Large Subunit (RNAPII LS) may play a central role in the cellular response to this promising anticancer agent. The stalling of an actively transcribing RNAPII LS at Et-743-DNA adducts is the initial cellular signal for transcription-coupled nucleotide excision repair (TC-NER). In this manner, Et-743 poisons TC-NER and produces DNA single strand breaks. Et-743 also inhibits the transcription and RNAPII LS-mediated expression of selected genes. Because the poisoning of TC-NER and transcription inhibition are critical components of the molecular response to Et-743 treatment, we have investigated if changes in RNAPII LS contribute to the disruption of these two cellular pathways. In addition, we have studied changes in RNAPII LS in two tumors for which clinical responses were reported in phase I/II clinical trials: renal cell carcinoma and Ewing\u27s sarcoma. Our results demonstrate that Et-743 induces degradation of the RNAPII LS that is dependent on active transcription, a functional 26S proteasome, and requires functional TC-NER, but not global genome repair. Additionally, we have provided the first experimental data indicating that degradation of RNAPII LS might lead to the inhibition of activated gene transcription. A set of studies performed in isogenic renal carcinoma cells deficient in von Hippel-Lindau protein, which is a ubiquitin-E3-ligase for RNAPII LS, confirmed the central role of RNAPII LS degradation in the sensitivity to Et-743. Finally, we have shown that RNAPII LS is also degraded in Ewing\u27s sarcoma tumors following Et-743 treatment and provide data to suggest that this event plays a role in decreased expression of the Ewing\u27s sarcoma oncoprotein, EWS-Fli1. Altogether, these data implicate degradation of RNAPII LS as a critical event following Et-743 exposure and suggest that the clinical activity observed in renal carcinoma and Ewing\u27s sarcoma may be mediated by disruption of molecular pathways requiring a fully functional RNAPII LS

Cardiovascular disease in survivors of childhood cancer: Insights into epidemiology, pathophysiology, and prevention

Cardiovascular disease (CVD), which includes cardiomyopathy/heart failure, coronary artery disease, stroke, pericardial disease, arrhythmias, and valvular and vascular dysfunction, is a major concern for long-term survivors of childhood cancer. There is clear evidence of increased risk of CVD largely attributable to treatment exposures at a young age, most notably anthracycline chemotherapy and chest-directed radiation therapy, and compounded by traditional cardiovascular risk factors accrued during decades after treatment exposure. Preclinical studies are limited; thus, it is a high priority to understand the pathophysiology of CVD as a result of anticancer treatments, taking into consideration the growing and developing heart. Recently developed personalized risk prediction models can provide decision support before initiation of anticancer therapy or facilitate implementation of screening strategies in at-risk survivors of cancer. Although consensus-based screening guidelines exist for the application of blood and imaging biomarkers of CVD, the most appropriate timing and frequency of these measures in survivors of childhood cancer are not yet fully elucidated. Longitudinal studies are needed to characterize the prognostic importance of subclinical markers of cardiovascular injury on long-term CVD risk. A number of prevention trials across the survivorship spectrum are under way, which include primary prevention (before or during cancer treatment), secondary prevention (after completion of treatment), and integrated approaches to manage modifiable cardiovascular risk factors. Ongoing multidisciplinary collaborations between the oncology, cardiology, primary care, and other subspecialty communities are essential to reduce therapeutic exposures and improve surveillance, prevention, and treatment of CVD in this high-risk population

Derivation of Anthracycline and Anthraquinone Equivalence Ratios to Doxorubicin for Late-Onset Cardiotoxicity

Importance: Anthracyclines are part of many effective pediatric cancer treatment protocols. Most pediatric oncology treatment groups assume that the hematologic toxicity of anthracycline agents is equivalent to their cardiotoxicity; for example, Children's Oncology Group substitution rules consider daunorubicin and epirubicin isoequivalent to doxorubicin, whereas mitoxantrone and idarubicin are considered 4 to 5 times as toxic as doxorubicin. Objective: To determine optimal dose equivalence ratios for late-onset cardiomyopathy between doxorubicin and other anthracyclines or the anthraquinone mitoxantrone. Design, Setting, and Participants: This multicenter cohort study of childhood cancer survivors who survived 5 or more years analyzed data pooled from 20367 participants in the Childhood Cancer Survivor Study treated from 1970 to 1999, 5741 participants in the Dutch Childhood Oncology Group LATER study diagnosed between 1963 and 2001, and 2315 participants in the St Jude Lifetime study treated from 1962 to 2005. Exposures: Cumulative doses of each agent (the anthracyclines doxorubicin, daunorubicin, epirubicin, and idarubicin; and the anthraquinone mitoxantrone) along with chest radiotherapy exposure were abstracted from medical records. Main Outcomes and Measures: Cardiomyopathy (severe, life-threatening, or fatal) by 40 years of age. Agent-specific Cox proportional hazards models evaluated cardiomyopathy risk, adjusting for chest radiotherapy, age at cancer diagnosis, sex, and exposure to anthracyclines or to an anthraquinone. An agent-specific cardiomyopathy equivalence ratio (relative to doxorubicin) was estimated for each dose category as a ratio of the hazard ratios, and then a weighted mean determined the overall agent-specific equivalence ratio across all dose categories. Results: Of 28423 survivors (46.4% female; median age at cancer diagnosis 6.1 years [range, 0.0-22.7 years]), 9330 patients received doxorubicin, 4433 received daunorubicin, 342 received epirubicin, 241 received idarubicin, and 265 received mitoxantrone. After a median follow-up of 20.0 years (range, 5.0-40.0 years) following receipt of a cancer diagnosis, 399 cardiomyopathy cases were observed. Relative to doxorubicin, the equivalence ratios were 0.6 (95% CI, 0.4-1.0) for daunorubicin, 0.8 (95% CI, 0.5-2.8) for epirubicin, and 10.5 (95% CI, 6.2-19.1) for mitoxantrone. Outcomes were too rare to generate idarubicin-specific estimates. Ratios based on a continuous linear dose-response relationship were similar for daunorubicin (0.5 [95% CI, 0.4-0.7]) and epirubicin (0.8 [95% CI, 0.3-1.4]). The relationship between mitoxantrone and doxorubicin appeared better characterized by a linear exponential model. Conclusions and Relevance: In a large data set assembled to examine long-term cardiomyopathy risk in childhood cancer survivors, daunorubicin was associated with decreased cardiomyopathy risk vs doxorubicin, whereas epirubicin was approximately isoequivalent. By contrast, the current hematologic-based doxorubicin dose equivalency of mitoxantrone (4:1) appeared to significantly underestimate the association of mitoxantrone with long-term cardiomyopathy risk