Project description:Fish species display huge differences in physical activity ranging from lethargy to migration of thousands of miles, making them an interesting model for human exercise. Here, we show a remarkable plasticity of zebrafish in response to exercise and induction of PGC1α (encoded by PPARGC1A), a dominant regulator of mitochondrial biogenesis. Forced expression of human PPARGC1A induces mitochondrial biogenesis, an exercise-like gene expression signature, and physical fitness comparable to wild-type animals trained in counter-current swim tunnels. We quantify a stoichiometric induction of the electron transport chain (ETC) in response to exercise or PGC1α expression, identified by a proteomic SWATH-MS workflow. Exercise or PGC1α expression induce the re-organization of the ETC into respiratory supercomplexes, and we show that ndufa4/ndufa4l, previously assigned to complex I, associates to free and supramolecular complex IV in vivo. Thus, zebrafish is a useful and experimentally tractable vertebrate model to study exercise biology, including ETC expression and assembly.
Project description:Exercise promotes a set of physiological adaptations known to provide long-term health benefits and it can play an important role in cardioprotection. However, the mechanisms underlying exercise-induced cardiac adaptation are not fully understood. In the present study, we examined cardiac adaptive responses to exercise training in the adult zebrafish and in the context of cardiac regeneration.We found that swimming-induced exercise increased cardiomyocyte proliferation and that this response was also found under regenerating conditions, when exercise was performed either prior to and after ventricular cryoinjury (CI). Exercise prior to CI resulted in a mild improvement in cardiac function and lesion recovery over the non-exercise condition.Transcriptomic profiling of regenerating ventricles in cryoinjured fish subjected to exercise revealed a differential regulation of genes related toregeneration as well as other biological processes potentially involved in the exercise response. Taken together, these results suggest that exercise constitutes a physiological stimulus thatmay help promote cardiomiogenic mechanisms of the vertebrate heart and that the zebrafish exercise model may be useful for evaluating the potential cardioprotective effects of exercise.
Project description:Hypoxic conditions and maximal exercise provide related but distinct energetic stresses for muscle tissue and induce different adaptations in skeletal muscle in mammals. High swim performance fish, including Danio Rerio (Zebrafish), are well-able to tolerate both hypoxia and fast swimming. Expression profiling was performed using microarrays to compare and contrast the adaptations to sustained hypoxia and repeated near maximal exercise in skeletal muscle of adult wild-type Zebrafish.
Project description:Physical activity is associated with beneficial adaptations in human and rodent metabolism. We studied over 50 complex traits before and after exercise intervention in middle-aged men and a panel of 100 diverse strains of female mice. Candidate gene analyses in three brain regions, muscle, liver, heart, and adipose tissue of mice revealed genetic drivers of clinically relevant traits including volitional exercise volume, muscle metabolism, adiposity, and hepatic lipids. Although ~33% of genes differentially expressed in skeletal muscle following the exercise intervention were similar in mice and men independent of BMI, responsiveness of adipose tissue to exercise-stimulated weight loss appears impacted by species and underlying genotype. We leveraged genetic diversity to generate prediction models of metabolic trait responsiveness to volitional activity offering a framework for advancing personalized exercise prescription. Finally, we make the human and mouse data publicly available via user-friendly web-based application to enhance data mining and hypothesis development.
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:Inguinal white adipose tissue (iWAT) is essential for the beneficial effects of exercise training on metabolic health. The underlying mechanisms for these effects are not fully understood and here, we test the hypothesis that exercise training results in a more favorable iWAT structural phenotype. Using biochemical, imaging, and multi-omics analyses we find that 11-days of wheel running in male mice causes profound iWAT remodeling including decreased extracellular matrix (ECM) deposition, increased vascularization and innervation. We identify adipose stem cells as one of the main contributors to training-induced ECM remodeling, show that the PRDM16 transcriptional complex is necessary for iWAT remodeling and beiging, and discover neuronal growth regulator 1 (NEGR1) as a link between PRDM16 and neuritogenesis. Moreover, we find that training causes a shift from hypertrophic to insulin-sensitive adipocyte subpopulations. Exercise training leads to remarkable adaptations to iWAT structure and cell-type composition that can confer beneficial changes in tissue metabolism.
Project description:Forced sustained swimming exercise at optimal speed enhances growth in many fish species, particularly through hypertrophy of the white skeletal muscle. The exact mechanism of this effect has not been resolved yet. To explore the mechanism, we first subjected wild-type zebrafish to an exercise protocol validated for exercise-enhanced growth, and showed that exercised zebrafish, which indeed showed enhanced growth, had higher cortisol levels than the non-exercised controls. A central role was therefore hypothesized for the steroid hormone cortisol acting through the Glucocorticoid receptor (Gr). Second, we subjected wild-type zebrafish and zebrafish with a mutant Gr to exercise at optimal, suboptimal and super-optimal speeds and compared them with non-exercised controls. Exercised zebrafish showed growth enhancement at all speeds, with highest growth at optimal speeds. In the Gr mutant fish, exercise resulted in growth enhancement similar to wild-type zebrafish, indicating that cortisol cannot be considered as a main determinant of exercise-enhanced growth. Finally, the transcriptome of white skeletal muscle tissue was analysed by RNA sequencing. The results of this analysis showed that in the muscle tissue of Gr mutant fish a lower number of genes is regulated by exercise than in wild-type fish (183 versus 351). A cluster of 36 genes was regulated by exercise in both wild-type and mutant fish. In this cluster, genes involved in transcriptional regulation and protein ubiquitination were overrepresented. Since growth was enhanced similarly in both wild-type fish and mutants, these processes may play an important role in exercise-enhanced growth.
Project description:Remyelination is a multistep regenerative process that results in the reformation of myelin sheaths around demyelinated axons and is a critical therapeutic target. Here we show that immediate access to a running wheel following toxin-induced demyelination in mice enhances oligodendrogenesis, myelin thickness, and the proportion of remyelinated axons. RNA-sequencing suggests broad activation of pro-remyelination pathways including phagocytosis by exercise and highlights peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1a) activation. Our study demonstrates that physical activity is an integrative means to enhance remyelination and details a multimodal mechanism including the pivotal PGC1a-dependent enhancement of myelin thickness.