Project description:The glucose-sensing Mondo pathway regulates expression of metabolic genes in mammals. Here, we have revealed an unexpected role of this pathway in vertebrate embryonic development. We characterized Mondo pathway function in the zebrafish and showed that knock-down of mondoa impaired the early morphogenetic movement of epiboly in zebrafish embryos. Expression of nsdhl , an enzyme of cholesterol and pregnenolone synthesis, was strongly reduced in these embryos. Loss of Nsdhl function likewise impaired epiboly and led to microtubule cytoskeleton defects in the embryo, similar to MondoA loss of function. Both epiboly and microtubule cytoskeleton defects were partially restored by pregnenolone treatment. Gene disruption of mondoa perturbed epiboly with only partial penetrance, likely due to compensatory changes in the expression of cholesterol/steroid metabolism genes. Collectively, our results show a novel role for MondoA in the regulation of early vertebrate development, connecting glucose, cholesterol and steroid hormone metabolism with early embryonic cell movements.
Project description:The glucose-sensing Mondo pathway regulates expression of metabolic genes in mammals. Here, we have revealed an unexpected role of this pathway in vertebrate embryonic development. We characterized Mondo pathway function in the zebrafish and showed that knock-down of mondoa impaired the early morphogenetic movement of epiboly in zebrafish embryos. Expression of nsdhl , an enzyme of cholesterol and pregnenolone synthesis, was strongly reduced in these embryos. Loss of Nsdhl function likewise impaired epiboly and led to microtubule cytoskeleton defects in the embryo, similar to MondoA loss of function. Both epiboly and microtubule cytoskeleton defects were partially restored by pregnenolone treatment. Gene disruption of mondoa perturbed epiboly with only partial penetrance, likely due to compensatory changes in the expression of cholesterol/steroid metabolism genes. Collectively, our results show a novel role for MondoA in the regulation of early vertebrate development, connecting glucose, cholesterol and steroid hormone metabolism with early embryonic cell movements.
Project description:In order to investigate the effect of MondoA loss on the expression of Myc-dependent genes, we performed a microarray analysis from RNAs isolated from TET21N cells expressing either control (siControl) or MondoA (siMondoA) siRNAs either with (NT) or without (Doxy) induced N-Myc expression. TET21N cells were grown in medium with either Doxy (Myc-Off) or No Treatment (Myc-On), then transiently transfected with either non-specific siRNA or MondoA siRNA in replicates. Cells were then lysed and RNA isolated.
Project description:MondoA (also known as MLXIP), a member of the MYC interactome, has been described as an example of a metabolic sensor. By assessing patient data sets we found that MondoA overexpression is associated with a worse survival in pediatric common acute lymphoblastic leukemia (B-ALL). Using CRISPR/Cas9 and RNA interference approaches, we observed that MondoA depletion reduces transformational capacity of B-ALL cells in vitro and dramatically inhibits malignant potential in an in vivo mouse model. Interestingly, reduced expression of MondoA in patient data sets correlated with enrichment in metabolic pathways. The loss of MondoA correlated with increased tricarboxylic acid (TCA) cycle activity. Mechanistically, MondoA senses metabolic stress in B-ALL cells by restricting oxidative phosphorylation through reduced PDH activity. Glutamine starvation conditions greatly enhance this effect and highlight the inability to mitigate metabolic stress upon loss of MondoA in B-ALL. CHIPseq revealed a modest but highly significant redistribution of MYC towards binding sites shared with MondoA upon loss of MondoA.
Project description:Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. To identify novel candidates for targeted treatment of childhood ALL, we performed a comprehensive transcriptome analysis yielding a set of genes specifically overexpressed in ALL. Among them we identified MondoA - a transcription factor regulating glycolysis in response to glucose availability. Here, we confirm that MondoA is highly overexpressed ALL, whereas the MondoA paralog, MondoB, is not expressed. Expression studies revealed that MondoA is not regulated by glucose availability in leukemia cells, but by the presence of lactate. An in silico MondoA promoter analysis identified two methylation-prone CpG-islands and four conserved binding sites for runt-related transcription factor 1 (RUNX1). In fact, MondoA and RUNX1 are significantly coexpressed in leukemia and experimental blockage of DNA methylation leads to a further induction of MondoA. In addition, using microarray profiling, gene-set enrichment analysis and RNA interference we provide for the first time evidence that MondoA expression not only increases glucose catabolism, but also maintains a more immature ALL phenotype, which is associated with enhanced survival and clonogenicity of leukemia cells. These data hint to an important contribution of MondoA to leukemia aggressiveness validating MondoA as an attractive candidate for targeted treatment of ALL. Two nonsense shRNA expressing control Nalm6 clones and three MondoA shRNA expressing Nalm6 clones were subjected to microarray analysis.
Project description:Bulk tissue RNA-sequencing of individual 24hpf zebrafish larvae to compare the gene expression values between wild type and foxg1a nonsense mutants (heterozygous and homozygous mutants). The mutation is a 5bp deletion (32bp from canonical start codon; AAATG deleted).