Project description:The role of OXPHOS respiratory supercomplexes remains still unknown. To answer this question we use as a model a SCAF1 null allele model in zebrafish. SCAF1 (cox7a2l) is the only supercomplex assembly factor identified in vertebrates and it is involved in the physical link of III-IV complexes. Therefore the SCAF1 null allele model lack all III-IV interactions. We demonstrate that supercomplexes provide an advantage in the optimization of metabolic resources.
Project description:Episodes of chronic stress can result in psychic disorders like post-traumatic stress disorder, but also promote the development of metabolic syndrome and type 2 diabetes. We hypothesize that muscle, as main regulator of whole-body energy expenditure, is a central target of acute and adaptive molecular effects of stress in this context. Here, we investigate the immediate effect of a stress period on energy metabolism in Musculus gastrocnemius in our established C57BL/6 chronic variable stress (Cvs) mouse model. Cvs decreased lean body mass despite increased energy intake, reduced circadian energy expenditure (EE), and substrate utilization. Cvs altered the proteome of metabolic components but not of the oxidative phosphorylation system (OXPHOS), or other mitochondrial structural components. Functionally, Cvs impaired the electron transport chain (ETC) capacity of complex I and complex II, and reduces respiratory capacity of the ETC from complex I to ATP synthase. Complex I-OXPHOS correlated to diurnal EE and complex II-maximal uncoupled respiration correlated to diurnal and reduced nocturnal EE. Bioenergetics assessment revealed higher optimal thermodynamic efficiencies (ƞ-opt) of mitochondria via complex II after Cvs. Interestingly, transcriptome and methylome were unaffected by Cvs, thus excluding major contributions to supposed metabolic adaptation processes. In summary, the preclinical Cvs model shows that metabolic pressure by Cvs is initially compensated by adaptation of mitochondria function associated with high thermodynamic efficiency and decreased EE to manage the energy balance. This counter-regulation of mitochondrial complex II may be the driving force to longitudinal metabolic changes of muscle physiological adaptation as the basis of stress memory.Chronic stress targets mitochondrial respiratory efficiency in the skeletal muscle of C57BL/6 mice.Nikolic A, Fahlbusch P, Wahlers N, Riffelmann NK, Jacob S, Hartwig S, Kettel U, Dille M, Al-Hasani H, Kotzka J, Knebel B. Cell Mol Life Sci. 2023 Mar 29;80(4):108. doi: 10.1007/s00018-023-04761-4.PMID: 36988756
Project description:Episodes of chronic stress can result in psychic disorders like post-traumatic stress disorder, but also promote the development of metabolic syndrome and type 2 diabetes. We hypothesize that muscle, as main regulator of whole-body energy expenditure, is a central target of acute and adaptive molecular effects of stress in this context. Here, we investigate the immediate effect of a stress period on energy metabolism in Musculus gastrocnemius in our established C57BL/6 chronic variable stress (Cvs) mouse model. Cvs decreased lean body mass despite increased energy intake, reduced circadian energy expenditure (EE), and substrate utilization. Cvs altered the proteome of metabolic components but not of the oxidative phosphorylation system (OXPHOS), or other mitochondrial structural components. Functionally, Cvs impaired the electron transport chain (ETC) capacity of complex I and complex II, and reduces respiratory capacity of the ETC from complex I to ATP synthase. Complex I-OXPHOS correlated to diurnal EE and complex II-maximal uncoupled respiration correlated to diurnal and reduced nocturnal EE. Bioenergetics assessment revealed higher optimal thermodynamic efficiencies (ƞ-opt) of mitochondria via complex II after Cvs. Interestingly, transcriptome and methylome were unaffected by Cvs, thus excluding major contributions to supposed metabolic adaptation processes. In summary, the preclinical Cvs model shows that metabolic pressure by Cvs is initially compensated by adaptation of mitochondria function associated with high thermodynamic efficiency and decreased EE to manage the energy balance. This counter-regulation of mitochondrial complex II may be the driving force to longitudinal metabolic changes of muscle physiological adaptation as the basis of stress memory.
Project description:Migrasomes are recently identified vesicular organelles that form on retraction fibers behind migrating cells, cellular contents are released from migrasome by a process named migracytosis. The function of migrasomes in living organisms is unknown. Here we show that migrasomes are formed during zebrafish gastrulation, signaling molecules such as chemokines are enriched in migrasomes. Migrasomes are clustered on spatially restricted area in embryo where they provide regional cues for organ morphogenesis. Our study shown migrasome is signaling organelles which integrate spatial and specific biochemical information to coordinate migrating cells in complex biological processes such as morphogenesis.
Project description:Background: Obesity is a worldwide public health problem with increasing prevalence and affects 80% of diabetes mellitus type 2 cases. Zebrafish (Danio rerio) are an established model organism for studying obesity and diabetes including diabetic microvascular complications. We aimed to determine whether physical activity is an appropriate tool to examine training effects in zebrafish and to analyse metabolic and transcriptional processes in trained zebrafish. Methods: A 2- and 8-weeks experimental training phase protocol with adult zebrafish in a swim tunnel system was established. We examined zebrafish basic characteristics before and after training such as body weight, body length and maximum speed and considered overfeeding as an additional parameter in the 8-weeks training protocol. Ultimately, the effects of training and overfeeding on blood glucose, muscle core metabolism and liver gene expression using RNA-Seq were investigated. Results: Zebrafish maximum speed was correlated with body length and was significantly increased after 2 weeks of training. Maximum swim speed further increased after 8 weeks of training in both the normalfed and the overfed groups, but training was found not to be sufficient in preventing weight gain in overfed fish. Metabolome and transcriptome profiling in trained fish exhibited increased blood glucose levels in the short-term and upregulated energy supply pathways in the long-term. Conclusion: Swim training is a valuable tool to study effects of physical activity in zebrafish, which is accompanied by metabolic and transcriptional adaptations.
Project description:High energy intake and, specifically, high dietary fat intake challenges the mammalian metabolism and correlates with many metabolic disorders, such as obesity and diabetes. Dietary restriction (DR) is, on the other hand, known to prevent the development of metabolic disorders. The current Western diets are highly enriched in fat and it is as yet unclear whether DR on a certain high-fat (HF) diet elicits similar beneficial effects on health. Here, we report that HF-DR improves metabolic health of mice, compared to mice receiving the same diet on an ad-libitum basis (HF-AL). Already after five weeks of restriction the serum levels of cholesterol and leptin were significantly decreased in HF-DR mice, while their glucose sensitivity and serum adiponectin levels were increased. The body weight and measured serum parameters remained stable in the following 7 weeks of restriction, implying metabolic adaptation. To understand the molecular events associated with this adaptation, we analysed gene expression in white adipose tissue (WAT) with whole genome microarrays. HF-DR strongly influenced gene expression in WAT; in total 8,643 genes were differentially expressed between both groups of mice, with a major role for genes involved in lipid metabolism and mitochondrial functioning. This was confirmed by qRT-PCR and substantiated by an increase in mitochondrial density in WAT of HF-DR mice. These results provide new insights in the metabolic flexibility of dietary restricted animals and suggest the development of substrate efficiency. Limiting food intake by decreasing portion sizes, while maintaining energy sufficiency, may similarly benefit metabolic health in humans.
Project description:Chronic stress can result in dysregulation of the cellular metabolism leading to severe disorders including depression, posttraumatic stress disorder but also the metabolic syndrome and type 2 diabetes. We aimed to determine the acute and adaptive effect of stress on energy metabolism in muscle tissue as the main determinant of whole-body energy expenditure. C57Bl6 mice under 15 days of chronic variable stress (Cvs) showed decreased lean mass despite increased energy intake. This was accompanied by reduced energy expenditure (EE) with a concomitant shift in substrate utilization depending on the circadian rhythm. The combination of omics approaches excluded stress effects on transcription and methylation processes in gastrocnemius muscle. Nevertheless, Cvs interfered with altered proteome composition in mitochondria on metabolic components, whilst OXPHOS and structural relevant components were unaltered. Functionally, Cvs resulted in impaired complex independent mitochondrial electron flow and reduced coupling efficiency that correlate for oxidative phosphorylation (state 3) of complex I to diurnal energy expenditure (EE) and for maximal uncoupled respiration (state 3u) of complex II to reduced diurnal and nocturnal EE. Bioenergetics assessment of mitochondria revealed higher optimal thermodynamic efficiencies (ƞ-opt) in Cvs muscle. Conclusion: These results show, that the Cvs reduced mitochondria respiration is associate with low rate of total EE, but does not primary affect transcription and genome methylation in muscle. However, the counter regulation by increased efficiency of complex II may be the driving force in to pave the way to longitudinal metabolic changes as basis of stress memory to muscle physiological adaptation.