Leptin is a hormone that plays a key role in controlling food intake and energy homeostasis. Skeletal muscle is an important target for leptin and recent studies have shown that leptin deficiency... Show moreLeptin is a hormone that plays a key role in controlling food intake and energy homeostasis. Skeletal muscle is an important target for leptin and recent studies have shown that leptin deficiency may lead to muscular atrophy. However, leptin deficiency-induced structural changes in muscles are poorly understood. The zebrafish has emerged as an excellent model organism for studies of vertebrate diseases and hormone response mechanisms. In this study, we explored ex-vivo magnetic resonance microimaging (& mu;MRI) methods to non-invasively assess muscle wasting in leptin-deficient (lepb(-/-)) zebrafish model. The fat mapping performed by using chemical shift selective imaging shows significant fat infiltration in muscles of lepb(-/-) zebrafish compared to control zebrafish. T-2 relaxation measurements show considerably longer T-2 values in the muscle of lepb(-/-) zebrafish. Multiexponential T-2 analysis detected a significantly higher value and magnitude of long T-2 component in the muscles of lepb(-/-) as compared to control zebrafish. For further zooming into the microstructural changes, we applied diffusion-weighted MRI. The results show a significant decrease in the apparent diffusion coefficient indicating increased constraints of molecular movements within the muscle regions of lepb(-/-) zebrafish. The use of the phasor transformation for the separation of diffusion-weighted decay signals showed a bi-component diffusion system which allows us to estimate each fraction on a voxel-wise basis. A substantial difference was found between the ratio of two components in lepb(-/-) and control zebrafish muscles, indicating alterations in diffusion behavior associated with the tissue microstructural changes in muscles of lepb(-/-) zebrafish as compared to control zebrafish. Taken together, our results demonstrate that the muscles of lepb(-/-) zebrafish undergo significant fat infiltration and microstructural changes leading to muscle wasting. This study also demonstrates that & mu;MRI provides excellent means to non-invasively study the microstructural changes in the muscles of the zebrafish model. Show less
Berlingerio, S.P.; He, J.L.; Groef, L. de; Taeter, H.; Norton, T.; Baatsen, P.; ... ; Levtchenko, E. 2021
Cystinosis is a rare, incurable, autosomal recessive disease caused by mutations in the CTNS gene. This gene encodes the lysosomal cystine transporter cystinosin, leading to lysosomal cystine... Show moreCystinosis is a rare, incurable, autosomal recessive disease caused by mutations in the CTNS gene. This gene encodes the lysosomal cystine transporter cystinosin, leading to lysosomal cystine accumulation in all cells of the body, with kidneys being the first affected organs. The current treatment with cysteamine decreases cystine accumulation, but does not reverse the proximal tubular dysfunction, glomerular injury or loss of renal function. In our previous study, we have developed a zebrafish model of cystinosis through a nonsense mutation in the CTNS gene and have shown that zebrafish larvae recapitulate the kidney phenotype described in humans. In the current study, we characterized the adult cystinosis zebrafish model and evaluated the long-term effects of the disease on kidney and extra renal organs through biochemical, histological, fertility and locomotor activity studies. We found that the adult cystinosis zebrafish presents cystine accumulation in various organs, altered kidney morphology, impaired skin pigmentation, decreased fertility, altered locomotor activity and ocular anomalies. Overall, our data indicate that the adult cystinosis zebrafish model reproduces several human phenotypes of cystinosis and may be useful for studying pathophysiology and long-term effects of novel therapies. Show less
Background Leptin plays a critical role in the regulation of metabolic homeostasis. However, the molecular mechanism and cross talks between leptin and metabolic pathways leading to metabolic... Show moreBackground Leptin plays a critical role in the regulation of metabolic homeostasis. However, the molecular mechanism and cross talks between leptin and metabolic pathways leading to metabolic homeostasis across different species are not clear. This study aims to explore the effects of leptin in mice and zebrafish larvae by integration of metabolomics and transcriptomics. Different metabolomic approaches including mass spectrometry, nuclear magnetic resonance (NMR) and high-resolution magic-angle-spinning NMR spectrometry were used to investigate the metabolic changes caused by leptin deficiency in mutant ob/ob adult mice and lepb(-/-) zebrafish larvae. For transcriptome studies, deep RNA sequencing was used. Results Thirteen metabolites were identified as common biomarkers discriminating ob/ob mice and lepb(-/-) zebrafish larvae from their respective wild type controls: alanine, citrulline, ethanolamine, glutamine, glycine, histidine, isoleucine, leucine, methionine, phenylalanine, putrescine, serine and threonine. Moreover, we also observed that glucose and lipid levels were increased in lepb(-/-) zebrafish larvae compared to the lepb(+/+) group. Deep sequencing showed that many genes involved in proteolysis and arachidonic acid metabolism were dysregulated in ob/ob mice heads and lepb mutant zebrafish larvae compared to their wild type controls, respectively. Conclusions Leptin deficiency leads to highly similar metabolic alterations in metabolites in both mice and zebrafish larvae. These metabolic changes show similar features as observed during progression of tuberculosis in human patients, mice and zebrafish larvae. In addition, by studying the transcriptome, we found similar changes in gene regulation related to proteolysis and arachidonic acid metabolism in these two different in vivo models. Show less
Leptin is a hormone which functions in the regulation of energy homeostasis via suppression of appetite. In zebrafish, there are two paralogous genes encoding leptin, called lepa and lepb. In a... Show moreLeptin is a hormone which functions in the regulation of energy homeostasis via suppression of appetite. In zebrafish, there are two paralogous genes encoding leptin, called lepa and lepb. In a gene expression study, we found that the lepb gene, not the lepa gene, was significantly downregulated under the state of insulin-resistance in zebrafish larvae, suggesting that the lepb plays a role in glucose homeostasis. In the current study, we characterised lepb-deficient (lepb(-/)(-)) adult zebrafish generated via a CRISPR-CAS9 gene editing approach by investigating whether the disruption of the lepb gene would result in the development of type 2 diabetes mellitus (T2DM) and diabetic complications. We observed that lepb(-)(/-)adult zebrafish had an increase in body weight, length and visceral fat accumulation, compared to age-matched control zebrafish. In addition, lepb(-/-) zebrafish had significantly higher blood glucose levels compared to control zebrafish. These data collectively indicate that lepb(-/-)adult zebrafish display the features of T2DM. Furthermore, we showed that lepb(-/-) adult zebrafish had glomerular hypertrophy and thickening of the glomerular basement membrane, compared to control zebrafish, suggesting that lepb(-/-) adult zebrafish develop early signs of diabetic nephropathy. In conclusion, our results demonstrate that lepb regulates glucose homeostasis and adiposity in zebrafish, and suggest that lepb(-/-) mutant zebrafish are a promising model to investigate the role of leptin in the development of T2DM and are an attractive model to perform mechanistic and therapeutic research in T2DM and its complications. Show less
Everaert, I.; He, J.L.; Hanssens, M.; Stautemas, J.; Bakker, K.; Albrecht, T.; ... ; Derave, W. 2020
doi:10.1152/ajprenal.00329.2019. Manipulation of circulating histidine-containing dipeptides (HCD) has been shown to affect the development of diabetes and early-stage diabetic nephropathy (DN).... Show moredoi:10.1152/ajprenal.00329.2019. Manipulation of circulating histidine-containing dipeptides (HCD) has been shown to affect the development of diabetes and early-stage diabetic nephropathy (DN). The aim of the present study was to investigate whether such interventions, which potentially alter levels of circulating HCD, also affect the development of advanced -stage DN. 'Iwo interventions, aerobic exercise training and overexpression of the human carnosinase-1 (hCNI) enzyme, were tested. BTBR ob/ob mice were either subjected to aerobic exercise training (20 wk) or genetically manipulated to overexpress hCNi, and different diabetes- and DNrelated markers were compared with control ob/ob and healthy (wild type) mice. An acute exercise study was performed to elucidate the effect of obesity, acute running, and hCNI overexpression on plasma HCD levels. Chronic aerobic exercise training did not affect the development of diabetes or DN, but hCNI overexpression accelerated hyperlipidemia and aggravated the development of alburninuria, mesangial matrix expansion, and glomerular hypertrophy- of ob/ob mice. In line, plasma, kidney, and muscle 11CD were markedly lower in oh/oh versus wild -type mice, and plasma and kidney HCD in particular were lower in ob/ob hCNI versus ob/ob mice but were unaffected by aerobic exercise. In conclusion, advanced glomerular damage is accelerated in mice overexpressing the hCNI enzyme but not protected by chronic exercise training. Interestingly, we showed, for the first time, that the development of DN is closely linked to renal HCD availability. Further research will have to elucidate whether the stimulation of renal HCD levels can he a therapeutic strategy to reduce the risk for developing DN. Show less
The aim of this study was to investigate the hepatotoxic effect and its underlying mechanism of aloe emodin (AE). AE was docked with the targets of NF-kappa B inflammatory pathway and P53 apoptosis... Show moreThe aim of this study was to investigate the hepatotoxic effect and its underlying mechanism of aloe emodin (AE). AE was docked with the targets of NF-kappa B inflammatory pathway and P53 apoptosis pathway respectively by using molecular docking technique. To verify the results of molecular docking and further investigate the hepatotoxicity mechanism of AE, the zebrafish Tg (fabp10: EGFP) was used as an animal model in vivo. The pathological sections of zebrafish liver were analyzed to observe the histopathological changes and Sudan black B was used to study whether there were inflammatory reactions in zebrafish liver or not. Then TdT-mediated dUTP Nick-End Labeling (TUNEL) was used to detect the apoptotic signal of zebrafish liver cells, finally the mRNA expression levels as well as the protein expression levels of the targets in NF-kappa B and P53 pathways in zebrafish were measured by quantitative Real-Time PCR (qRT-PCR) and western blot. Molecular docking results showed that AE could successfully dock with all the targets of NF-kappa B and P53 pathways, and the docking scores of most of the targets were equal to or higher than that of the corresponding ligands. Pathological sections showed AE could cause zebrafish liver lesions and the result of Sudan black B staining revealed that AE blackened the liver of zebrafish with Sudan black B. Then TUNEL assay showed that a large number of dense apoptotic signals were observed in AE group, mainly distributed in the liver and yolk sac of zebrafish. The results of qRT-PCR and western blot showed that AE increased the mRNA and protein expression levels of pro-inflammatory and pro-apoptotic targets in NF-kappa B and P53 pathways. AE could activate the NF-kappa B inflammatory pathway and the P53 apoptosis pathway, and its hepatotoxic mechanism was related to activation of NF-.B-P53 inflammation-apoptosis pathways. Show less
