Diet-MEF2 Interactions Shape Lipid Droplet Diversification in Muscle to Influence Drosophila Lifespan
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ABSTRACT:
PROVIDER: PRJNA616015 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR11441000.fastq.gz | Fastqsanger.gz | |||
| SRR11441000_1.fastq.gz | Fastqsanger.gz | |||
| SRR11441000_2.fastq.gz | Fastqsanger.gz | |||
| SRR11441001.fastq.gz | Fastqsanger.gz | |||
| SRR11441001_1.fastq.gz | Fastqsanger.gz |
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Project description:The number, size, and composition of lipid droplets can be influenced by dietary changes that shift energy substrate availability. This diversification of lipid droplets can promote metabolic flexibility and shape cellular stress responses in unique tissues with distinctive metabolic roles. Using Drosophila, we uncovered a role for myocyte enhancer-factor 2 (MEF2) in modulating diet-dependent lipid droplet diversification within adult striated muscle, impacting mortality rates. Muscle-specific attenuation of MEF2, whose chronic activation maintains glucose and mitochondrial homeostasis, leads to the accumulation of large, cholesterol ester-enriched intramuscular lipid droplets in response to high calorie, carbohydrate sufficient diets. The diet-dependent accumulation of these lipid droplets also correlates with both enhanced stress protection in muscle and increases in organismal lifespan. Furthermore, MEF2 attenuation releases an antagonistic regulation of cell cycle gene expression programs, and up-regulation of Cyclin E is required for diet-and-MEF2 dependent diversification of intramuscular lipid droplets. The integration of MEF2-regulated gene expression networks with dietary responses thus plays a critical role in shaping muscle metabolism and function, further influencing organismal lifespan. Together, these results highlight a potential protective role for intramuscular lipid droplets during dietary adaptation.
2020-08-11 | GSE147676 | GEO
Project description:The number, size, and composition of lipid droplets can be influenced by dietary changes that shift energy substrate availability. This diversification of lipid droplets can promote metabolic flexibility and shape cellular stress responses in unique tissues with distinctive metabolic roles. Using Drosophila, we uncovered a role for myocyte enhancer factor 2 (MEF2) in modulating diet-dependent lipid droplet diversification within adult striated muscle, impacting mortality rates. Muscle-specific attenuation of MEF2, whose chronic activation maintains glucose and mitochondrial homeostasis, leads to the accumulation of large, cholesterol ester-enriched intramuscular lipid droplets in response to high calorie, carbohydrate-sufficient diets. The diet-dependent accumulation of these lipid droplets also correlates with both enhanced stress protection in muscle and increases in organismal lifespan. Furthermore, MEF2 attenuation releases an antagonistic regulation of cell cycle gene expression programs, and up-regulation of Cyclin E is required for diet- and MEF2-dependent diversification of intramuscular lipid droplets. The integration of MEF2-regulated gene expression networks with dietary responses thus plays a critical role in shaping muscle metabolism and function, further influencing organismal lifespan. Together, these results highlight a potential protective role for intramuscular lipid droplets during dietary adaptation.
| S-EPMC7433001 | biostudies-literature
Project description:Expression profiling in hippocampal neurons to identify genes upregulated in response to ectopic MEF2 activation by MEF2-VP16-ER Experiments were conducted to identify activity-regulated MEF2 target genes. Keywords: Gene activation time course
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Project description:Testosterone production by Leydig cells is a tightly regulated process requiring synchronized expression of several steroidogenic genes by numerous transcription factors. Myocyte enhancer factor 2 (MEF2) is a transcription factor recently identified in somatic cells of the male gonad. In other tissues, MEF2 is an essential regulator of organogenesis and cell differentiation. So far in the testis, MEF2 was found to regulate Leydig cell steroidogenesis by controlling Nr4a1 and Star gene expression. To expand our understanding of the role of MEF2 in Leydig cells, we performed microarray analyses of MA-10 Leydig cells depleted in MEF2 and results were analyzed using the Partek and IPA softwares. Several genes were differentially expressed in MEF2-depleted Leydig cells and 15 were validated by qPCR. A large number of these genes are known to be involved in fertility, gonad morphology and steroidogenesis and include Pde8a, Por, Ahr, Bmal1, Cyp1a1, Cyp1b1, Map2k1, Tsc22d3, Nr0b2, Smad4, and Star, which were all downregulated in the absence of MEF2. In silico analyses revealed the presence of MEF2 binding sites within the first 2 kb upstream the transcription start site of the Por, Bmal1, and Nr0b2 promoters, which suggests a direct regulation by MEF2. Using transient transfections in MA-10 Leydig cells, siRNA knockdown, and a MEF2-Engrailed dominant negative, we found that MEF2 activates the Por, Bmal1 and Nr0b2 promoters and that this requires an intact MEF2 element. Our results identify novel target genes for MEF2 and define MEF2 as an important regulator of Leydig cell function and male reproduction.
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Project description:The myogenic regulatory factor MRF4 is expressed at high levels in myofibers of adult skeletal muscle, but its function is unknown. Here we show that knockdown of MRF4 in adult muscle causes hypertrophy and prevents denervation-induced atrophy. This effect is accompanied by increased protein synthesis and the widespread activation of genes involved in muscle contraction, excitation-contraction coupling and energy metabolism, many of which are known targets of MEF2 transcription factors. Genes regulated by MEF2 represent the top-ranking gene set enriched after Mrf4 RNAi, and a MEF2 reporter is inhibited by co-transfected MRF4 and activated by Mrf4 RNAi. The role of MEF2 in mediating the effect of MRF4 knockdown is supported by the finding that Mrf4 RNAi-dependent increase in fiber size is prevented by dominant negative MEF2, while constitutively active MEF2 is able to induce myofiber hypertrophy. The nuclear localization of the MEF2 co-repressor HDAC4 is impaired by Mrf4 knockdown, suggesting that MRF4 acts by stabilizing a repressor complex that controls MEF2 activity. The demonstration that fiber size in adult skeletal muscle is controlled by the MRF4-MEF2 axis opens new perspectives in the search for therapeutic targets to prevent muscle wasting, in particular sarcopenia and cachexia.
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Project description:MEF2 (MEF2A, B, C, D) transcription factors (TFs) regulate many complex biological responses, spanning from differentiation to stress-adaptation. MEF2’s activities are therefore strictly regulated. A family of transcriptional repressors: the class IIa HDACs, which includes HDAC4, 5, 7, 9, is intimately involved in the fine tuning of MEF2 activities. In many cancer types the physiological cycle of turning on and off of MEF2 transcriptional activities is subverted due to mutations or dysregulations. On the basis of loss-of-function experiments, MEF2 factors are classified sometimes as oncogenes and sometimes as tumor suppressors. With this project we aimed to address this apparent paradox. Soft-tissue sarcomas and leiomyosarcomas (LMSs) in particular are tumors characterized by a strong repression of MEF2, which is achieved through an increase in proteasomal-mediated degradation of MEF2 proteins or in the repression exerted by HDAC4 and HDAC9. MEF2 degradation prevails in a cellular model of low-grade tumors (SK-LMS-1 cells), while in a model of high-grade LMSs (SK-UT-1 cells) MEF2 are converted into transcriptional repressors of specific genome loci. In this latter case the knock down of MEF2D and MEF2A causes the de-repression of some MEF2-target genes and, surprisingly, has a tumor suppressive effect. Our results suggest that MEF2 could provide different contributions during tumor progression in relation to the specific cellular microenvironment.
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Project description:Expression profiling in hippocampal neurons to identify genes upregulated in response to ectopic MEF2 activation by MEF2-VP16-ER; Experiments were conducted to identify activity-regulated MEF2 target genes. Experiment Overall Design: Neurons expressed either control MEF2deltaDBD-VP16-ER or MEF2-VP16-ER and expression profiling was conducted before and after 4-OH-Tamoxifen (4OHT) application.
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