Roles for hypothalamic reactive oxygen species (ROS) in the modulation of circuit activity of the melanocortin system were proposed1,2,. Here we show that suppression of ROS diminished pro-opiomelanocortin (POMC) cell activation and promoted the activity of neuropeptide Y- (NPY)/agouti related peptide- (AgRP) neurons and feeding, whereas ROS activated POMC neurons and reduced feeding. ROS in POMC neurons were positively correlated with leptin levels in lean and ob/ob animals a relationship diminished in diet-induced obese (DIO) mice. High fat feeding resulted hypothalamic proliferation of peroxisomes and elevated PPARγ mRNA levels. Peroxisome proliferation in POMC neurons by the PPARγ agonist, rosiglitazone, decreased ROS levels and increased food intake in lean mice on high fat diet. Suppression of peroxisome proliferation in the hypothalamus by the PPAR antagonist, GW9662, increased ROS and c-fos expression in POMC neurons, reversed high fat feeding-triggered elevated NPY/AgRP and low POMC neuronal firing, and, resulted in decreased feeding of DIO mice. Finally, central administration of ROS alone increased c-fos and pStat3 expression in POMC neurons and reduced feeding of DIO animals. These observations unmask a previously unknown hypothalamic cellular event associated with peroxisomes and ROS in the central regulation of energy metabolism in states of leptin resistance.

Sleep deprivation, shift work, and jet lag all disrupt normal biological rhythms and have major impacts on health; however, circadian disorganization has never been shown as a causal risk factor in organ disease. We now demonstrate devastating effects of rhythm disorganization on cardiovascular and renal integrity and that interventions based on circadian principles prevent disease pathology caused by a short-period mutation (tau) of the circadian system in hamsters. The point mutation in the circadian regulatory gene, casein kinase-1epsilon, produces early onset circadian entrainment with fragmented patterns of behavior in +/tau heterozygotes. Animals die at a younger age with cardiomyopathy, extensive fibrosis, and severely impaired contractility; they also have severe renal disease with proteinuria, tubular dilation, and cellular apoptosis. On light cycles appropriate for their genotype (22 h), cyclic behavioral patterns are normalized, cardiorenal phenotype is reversed, and hearts and kidneys show normal structure and function. Moreover, hypertrophy does not develop in animals whose suprachiasmatic nucleus was ablated as young adults. Circadian organization therefore is critical for normal health and longevity, whereas chronic global asynchrony is implicated in the etiology of cardiac and renal disease.

5-hydroxymethylcytosine (5-hmC), a derivative of 5-methylcytosine (5-mC), is abundant in the brain for unknown reasons. Our goal was to characterize the genomic distribution of 5-hmC and 5-mC in human and mouse tissues. We assayed 5-hmC using glucosylation coupled with restriction enzyme digestion, and interrogation on microarrays. We detected 5-hmC enrichment in genes with synapse-related functions in both human and mouse brain. We also identified substantial tissue-specific differential distributions of these DNA modifications at the exon-intron boundary, in both human and mouse. This boundary change was mainly due to 5-hmC in the brain, but due to 5-mC in non-neural contexts. This pattern was replicated in multiple independent datasets and with single molecule sequencing. Moreover, in human frontal cortex, constitutive exons contained higher levels of 5-hmC, relative to alternatively-spliced exons. Our study suggests a novel role for 5-hmC in RNA splicing and synaptic function in the brain.