Meal-Related Asprosin Serum Levels Are Affected by Insulin Resistance and Impaired Fasting Glucose in Children With Obesity

Asprosin physiologically increases in fasting conditions and decreases with refeeding and has been implicated in glucose homeostasis. An alteration of meal-related circadian oscillation of asprosin has been suggested in adults affected by type 2 diabetes mellitus.Aims of this study were to test the hypothesis of an alteration in the meal-related variation of asprosin levels in non-diabetic children and adolescents with obesity and to assess which metabolic variables condition this variation in non-diabetic children and adolescents with obesity. This is a cross-sectional study which included 79 children and adolescents with obesity. Children underwent clinical and biochemical assessments, including oral glucose tolerance test (OGTT), and liver ultrasound evaluation. Asprosin serum levels were measured by an enzyme-linked immunosorbent assay at a fasting state and at the 120-minute OGTT timepoint (2h-postprandial asprosin). Fasting and 2h-postprandial asprosin serum levels did not significantly differ in the entire study population (374.28 ± 77.23 vs 375.27 ± 81.26;p=0.837). 55.7% of patients had a significant increase in 2h-postprandial asprosin compared with fasting levels. The asprosin level increase condition was significantly associated with HOMA-IR (OR,1.41; 95%CI,1.005-1.977; p=0.047), fasting glycaemia (OR,1.073; 95%CI,1.009-1.141;p=0.024) and HOMA-B (OR,0.99; 95%CI,0.984-0.999; p=0.035). Moreover, the IFG condition was associated with the increase in asprosin levels (OR, 3.040; 95%CI, 1.095-8.436; p=0.033), even after adjustment for HOMA-IR, BMI SDS, sex and pubertal stage. Insulin resistance and IFG influence meal-related changes of asprosin serum levels in our study population of obese, non-diabetic, children. Alteration of asprosin circadian secretion might be an early biomarker of impaired glucose regulation in obese children with insulin resistance.

Multi-omic analysis reveals the biochemical changes underpinning the varied phenotypes of the Arabidopsis long-period mutant rve 4 6 8

Plants are able to sense changes in their light environments, such as the onset of day and night, as well as anticipate these changes in order to adapt and survive. Central to this ability is the plant circadian clock, a molecular circuit that precisely orchestrates plant cell processes over the course of a day. REVEILLE proteins (RVEs) are recently discovered members of the plant circadian circuitry that activate the evening complex and PRR genes to maintain regular circadian oscillation. The RVE 8 protein and its two homologs, RVE 4 and 6, have been shown to limit the length of the circadian period, with rve 4 6 8 triple-knockout plants possessing an elongated period along with increased leaf surface area, biomass and delayed flowering relative to wild-type Col-0 plants. Here, using a multi-omics approach consisting of phenomics, transcriptomics, proteomics, and metabolomics we demonstrate how RVE8-like proteins impact diel plant cell function and draw novel connections to a number of plant cell processes that underpin the growth and development phenotypes observed in rve 4 6 8 plants. In particular, we reveal that loss of RVE8-like proteins results in altered carbohydrate, organic acid and lipid metabolism, including a starch excess phenotype at ZT0. We further demonstrate that RVE8-like proteins have a unique impact on the abundance and phosphorylation of 26S proteasome subunits, in addition to impacting the abundance and phosphorylation status of a number of protein kinases. Overall, this robust, multi-omic dataset, provides substantial new insights into RVE8-like protein function and the far reaching impact RVE8-like proteins have on the diel plant cell environment.

Enhanced Circadian Clock in MSCs-Based Cytotherapy Ameliorates Age-Related Temporomandibular Joint Condyle Degeneration

Aging has been proven to be one of the major causes of temporomandibular joint (TMJ) disability and pain in older people. Peripheral circadian rhythms play a crucial role in endochondral ossification and chondrogenesis. However, the age-related alterations of circadian clock in TMJ structures are seldom reported. In the current study, TMJ condyles were extracted from young (4-month-old), middle-aged (10-month-old), and old-aged (20-month-old) adults to detect the morphology and circadian oscillation changes in TMJ condyles with aging. The transcriptome profile of Bmal1-deleted bone-marrow mesenchymal stem cells (BMSCs) and controls were explored to reveal the circadian-related differences at the molecular level. Furthermore, the reparative effects of Bmal1-overexpressed BMSCs-based cytotherapy in aged TMJ condyles were investigated in vitro and in vivo. Aged TMJ condyles displayed damaged tissue structure and an abolished circadian rhythm, accompanied by a progressively decreasing chondrogenesis capability and bone turnover activities. The deletion of Bmal1 significantly down-regulated chondrogenesis-related genes Prg4, Sox9, and Col7a1. Bmal1-overexpressed BMSCs presented improved migration capability ex vivo and attenuated age-related TMJ condylar degeneration in vivo. These data demonstrate the crucial role of circadian timing in the maintenance of osteochondral homeostasis, and indicate the potential clinical prospects of circadian-modified MSCs therapy in tissue regeneration.

CHRONO and DEC1/DEC2 compensate for lack of CRY1/CRY2 in expression of coherent circadian rhythm but not in generation of circadian oscillation in the neonatal mouse SCN

Clock genes Cry1 and Cry2, inhibitory components of core molecular feedback loop, are regarded as critical molecules for the circadian rhythm generation in mammals. A double knockout of Cry1 and Cry2 abolishes the circadian behavioral rhythm in adult mice under constant darkness. However, robust circadian rhythms in PER2::LUC expression are detected in the cultured suprachiasmatic nucleus (SCN) of Cry1/Cry2 deficient neonatal mice and restored in adult SCN by co-culture with wild-type neonatal SCN. These findings led us to postulate the compensatory molecule(s) for Cry1/Cry2 deficiency in circadian rhythm generation. We examined the roles of Chrono and Dec1/Dec2 proteins, the suppressors of Per(s) transcription similar to CRY(s). Unexpectedly, knockout of Chrono or Dec1/Dec2 in the Cry1/Cry2 deficient mice did not abolish but decoupled the coherent circadian rhythm into three different periodicities or significantly shortened the circadian period in neonatal SCN. DNA microarray analysis for the SCN of Cry1/Cry2 deficient mice revealed substantial increases in Per(s), Chrono and Dec(s) expression, indicating disinhibition of the transactivation by BMAL1/CLOCK. Here, we conclude that Chrono and Dec1/Dec2 do not compensate for absence of CRY1/CRY2 in the circadian rhythm generation but contribute to the coherent circadian rhythm expression in the neonatal mouse SCN most likely through integration of cellular circadian rhythms.

Mitochondrial stress-induced GDF15-GFRAL axis promotes anxiety-like behavior and CRH-dependent anorexia

Growth differentiation factor 15 (GDF15) is a stress-induced cytokine that modulates food intake and energy metabolism. Until now, most mechanistic studies on GDF15 rely on pharmacological interventions using exogenous GDF15, but little is known about its mode of action when induced both chronically and endogenously. Mitochondrial stress is one of the most described physiological conditions that induces GDF15, and therefore an important model to study the underlying mechanisms of endogenous GDF15 action. Here, using a mouse model of mitochondrial dysfunction via elevated respiratory uncoupling in skeletal muscle, we show a circadian oscillation of muscle-derived GDF15 to promote a daytime-restricted anorexia without signs of nausea or reduced physical activity, contrary to findings using recombinant GDF15. We find that mitochondrial stress-induced GDF15 associates with increased anxiety and hypothalamic corticotropin releasing hormone (CRH) induction, without further activation of the hypothalamic-pituitary-adrenal (HPA) axis and corticosterone response. Strikingly, the daytime-restricted anorexia, lean phenotype, systemic shift in substrate metabolism and anxiety-like behavior are completey abolished in conditions of mitochondrial stress coupled with genetic ablation of the GDF15 receptor GDNF receptor alpha-like (GFRAL), which is predominantly expressed in the hindbrain. Finally, we demonstrate that stress-induced GDF15-GFRAL signaling is required for hypothalamic CRH induction to control diurnal food intake in a CRH-receptor 1 (CRHR1)-dependent manner. With this, we uncover for the first time a molecular target of the GDF15-GFRAL axis that links anxiolytic and anorectic behavior as downstream effects of the chronic activation of this pathway by mitochondrial stress.

Monochromic Radiations Provided by Light Emitted Diode (LED) Modulate Infection and Defense Response to Fire Blight in Pear Trees

Pathogenesis-related (PR) proteins are part of the systemic signaling network that perceives pathogens and activates defenses in the plant. Eukaryotic and bacterial species have a 24-h ‘body clock’ known as the circadian rhythm. This rhythm regulates an organism’s life, modulating the activity of the phytochromes (phys) and cryptochromes (crys) and the accumulation of the corresponding mRNAs, which results in the synchronization of the internal clock and works as zeitgeber molecules. Salicylic acid accumulation is also under light control and upregulates the PR genes expression, increasing plants’ resistance to pathogens. Erwinia amylovora causes fire blight disease in pear trees. In this work, four bacterial transcripts (erw1-4), expressed in asymptomatic E. amylovora-infected pear plantlets, were isolated. The research aimed to understand how the circadian clock, light quality, and related photoreceptors regulate PR and erw genes expression using transgenic pear lines overexpressing PHYB and CRY1 as a model system. Plantlets were exposed to different circadian conditions, and continuous monochromic radiations (Blue, Red, and Far-Red) were provided by light-emitting diodes (LED). Results showed a circadian oscillation of PR10 gene expression, while PR1 was expressed without clear evidence of circadian regulation. Bacterial growth was regulated by monochromatic light: the growth of bacteria exposed to Far-Red did not differ from that detected in darkness; instead, it was mildly stimulated under Red, while it was significantly inhibited under Blue. In this regulatory framework, the active form of phytochrome enhances the expression of PR1 five to 15 fold. An ultradian rhythm was observed fitting the zeitgeber role played by CRY1. These results also highlight a regulating role of photoreceptors on the expression of PRs genes in non-infected and infected plantlets, which influenced the expression of erw genes. Data are discussed concerning the regulatory role of photoreceptors during photoperiod and pathogen attacks.

Abstract 21: Sex Differences In Circadian Blood Pressure

Hypertensive patients frequently show a lack of 10% decline in nighttime (or nondipping) blood pressure (BP), which is a strong predictor of a cardiovascular event. Clock genes are essential regulators in diurnal BP in the vasculature during hypertension. However, little is known if vascular circadian clock factors influence BP rhythms in a sex-dependent manner. To test the hypothesis that AngII-induced hypertension disrupts the expression pattern of peripheral clock genes, male and female C57Bl/6J mice were subjected to AngII (700 ng/kg/min) infusion for two weeks. BP was measured by radiotelemetry (N=7/group). After two weeks, the animals were sacrificed during daytime or nighttime, and aortas were assessed for expression of clock genes (Per1, Per2, Bmal1) and estrogen receptors (ERα and GPER). Two-way ANOVA was used to compare light-dark cycle and AngII treatment effects. Hypertensive females (MAP: day 121 ± 9 vs. night 126 ± 10 mmHg, P=0.39; 7.3% dipping) but not males (MAP: day 128 ± 3 vs. night 140 ± 2 mmHg, P=0.01; >10% dipping) developed a non-dipping phenotype. AngII-hypertension amplified the circadian pattern of Per1 in the male aorta but removed the Per1 circadian variation in the female aorta. AngII did not alter Per2 oscillation in the aorta of either sex. Bmal1 patterns were also amplified in males and reversed in females. In response to AngII, aortic ERα expression was augmented during the day in females (control 287 ± 14 vs. AngII 413 ± 42 copies/ng RNA; P=0.01) but not in males (P=0.34). Furthermore, GPER expression exhibited a circadian oscillation in control (day 9 ± 1 vs. night 20 ± 7.6 copies/RNA ng) and hypertensive males (day 12 ± 17 vs. night 20 ± 5 copies/RNA ng, P=0.04), but not in females. In conclusion, sex differences exist in non-dipping BP patterns and circadian disruption of estrogen receptors and clock genes Per1 and Bmal1 in the vasculature after AngII treatment. This data suggest that females may be more vulnerable to circadian disruption during hypertension.