ABSTRACT
Peroxisome proliferator-activated receptor δ (PPARδ) is a critical regulator of energy metabolism in the heart. Here, we propose a mechanism that integrates two deleterious characteristics of heart failure, hypoxia and a metabolic shift toward glycolysis, involving the microRNA cluster miR-199aâ¼214 and PPARδ. We demonstrate that under hemodynamic stress, cardiac hypoxia activates DNM3os, a noncoding transcript that harbors the microRNA cluster miR-199aâ¼214, which shares PPARδ as common target. To address the significance of miR-199aâ¼214 induction and concomitant PPARδ repression, we performed antagomir-based silencing of both microRNAs and subjected mice to biomechanical stress to induce heart failure. Remarkably, antagomir-treated animals displayed improved cardiac function and restored mitochondrial fatty acid oxidation. Taken together, our data suggest a mechanism whereby miR-199aâ¼214 actively represses cardiac PPARδ expression, facilitating a metabolic shift from predominant reliance on fatty acid utilization in the healthy myocardium toward increased reliance on glucose metabolism at the onset of heart failure.
Subject(s)
Fatty Acids/metabolism , Hypoxia , MicroRNAs/metabolism , Mitochondria/metabolism , Myocardium/metabolism , PPAR delta/metabolism , 3' Untranslated Regions , Animals , Base Sequence , Fatty Acids/chemistry , Gene Expression Profiling , Gene Silencing , Heart Failure/etiology , Heart Failure/metabolism , Humans , Mice , MicroRNAs/antagonists & inhibitors , Mitochondria/genetics , Multigene Family , Oligonucleotides, Antisense/metabolism , Oxidation-Reduction , PPAR delta/antagonists & inhibitors , PPAR delta/genetics , Stress, MechanicalABSTRACT
Despite the sequence and structural conservation between cryptochromes and photolyases, members of the cryptochrome/photolyase (flavo)protein family, their functions are divergent. Whereas photolyases are DNA repair enzymes that use visible light to lesion-specifically remove UV-induced DNA damage, cryptochromes act as photoreceptors and circadian clock proteins. To address the functional diversity of cryptochromes and photolyases, we investigated the effect of ectopically expressed Arabidopsis thaliana (6-4)PP photolyase and Potorous tridactylus CPD-photolyase (close and distant relatives of mammalian cryptochromes, respectively), on the performance of the mammalian cryptochromes in the mammalian circadian clock. Using photolyase transgenic mice, we show that Potorous CPD-photolyase affects the clock by shortening the period of behavioral rhythms. Furthermore, constitutively expressed CPD-photolyase is shown to reduce the amplitude of circadian oscillations in cultured cells and to inhibit CLOCK/BMAL1 driven transcription by interacting with CLOCK. Importantly, we show that Potorous CPD-photolyase can restore the molecular oscillator in the liver of (clock-deficient) Cry1/Cry2 double knockout mice. These data demonstrate that a photolyase can act as a true cryptochrome. These findings shed new light on the importance of the core structure of mammalian cryptochromes in relation to its function in the circadian clock and contribute to our further understanding of the evolution of the cryptochrome/photolyase protein family.
Subject(s)
Circadian Clocks/physiology , Cryptochromes/metabolism , Deoxyribodipyrimidine Photo-Lyase/metabolism , Potoroidae/metabolism , ARNTL Transcription Factors/genetics , ARNTL Transcription Factors/metabolism , Animals , CLOCK Proteins/genetics , CLOCK Proteins/metabolism , COS Cells , Cells, Cultured , Chlorocebus aethiops , Circadian Clocks/genetics , Cryptochromes/deficiency , Cryptochromes/genetics , Deoxyribodipyrimidine Photo-Lyase/genetics , HEK293 Cells , Humans , Immunoblotting , Liver/metabolism , Luciferases/genetics , Luciferases/metabolism , Luminescent Measurements/methods , Mice , Mice, Knockout , Mice, Transgenic , NIH 3T3 Cells , Protein Binding , Reverse Transcriptase Polymerase Chain Reaction , TransfectionABSTRACT
Dietary restriction (DR) extends lifespan and increases resistance to multiple forms of stress, including ischemia reperfusion injury to the brain and heart in rodents. While maximal effects on lifespan require long-term restriction, the kinetics of onset of benefits against acute stress is not known. Here, we show that 2-4 weeks of 30% DR improved survival and kidney function following renal ischemia reperfusion injury in mice. Brief periods of water-only fasting were similarly effective at protecting against ischemic damage. Significant protection occurred within 1 day, persisted for several days beyond the fasting period and extended to another organ, the liver. Protection by both short-term DR and fasting correlated with improved insulin sensitivity, increased expression of markers of antioxidant defense and reduced expression of markers of inflammation and insulin/insulin-like growth factor-1 signaling. Unbiased transcriptional profiling of kidneys from mice subject to short-term DR or fasting revealed a significant enrichment of signature genes of long-term DR. These data demonstrate that brief periods of reduced food intake, including short-term daily restriction and fasting, can increase resistance to ischemia reperfusion injury in rodents and suggest a rapid onset of benefits of DR in mammals.
Subject(s)
Caloric Restriction , Fasting , Kidney Diseases/diet therapy , Reperfusion Injury/diet therapy , Animals , Gene Expression Regulation , Insulin/metabolism , Insulin-Like Growth Factor I/metabolism , Kidney Diseases/genetics , Kidney Diseases/metabolism , Kidney Diseases/physiopathology , Kidney Function Tests , Male , Mice , Mice, Inbred C57BL , Oligonucleotide Array Sequence Analysis , Reperfusion Injury/genetics , Reperfusion Injury/metabolism , Reperfusion Injury/physiopathology , Signal Transduction , Survival Rate , Time Factors , Transcription, GeneticABSTRACT
Photolyase transgenic mice have opened new avenues to improve our understanding of the cytotoxic effects of ultraviolet (UV) light on skin by providing a means to selectively remove either cyclobutane pyrimidine dimers (CPDs) or pyrimidine (6-4) pyrimidone photoproducts. Here, we have taken a genomics approach to delineate pathways through which CPDs might contribute to the harmful effects of UV exposure. We show that CPDs, rather than other DNA lesions or damaged macromolecules, comprise the principal mediator of the cellular transcriptional response to UV. The most prominent pathway induced by CPDs is that associated with DNA double-strand break (DSB) signalling and repair. Moreover, we show that CPDs provoke accumulation of gamma-H2AX, P53bp1 and Rad51 foci as well as an increase in the amount of DSBs, which coincides with accumulation of cells in S phase. Thus, conversion of unrepaired CPD lesions into DNA breaks during DNA replication may comprise one of the principal instigators of UV-mediated cytotoxicity.
