Project description:The “Mlx” and “Myc” Networks share many common gene targets. Just as Myc’s activity depends upon its heterodimerization with Max, the Mlx Network requires that the Max-like factor Mlx associate with the Myc-like factors MondoA or ChREBP. We show here that body-wide Mlx inactivation, like that of Myc, accelerates numerous aging-related phenotypes pertaining to body habitus and metabolism. The deregulation of numerous aging-related Myc target gene sets is also accelerated. Among other functions, these gene sets often regulate ribosomal and mitochondrial structure and function, genomic stability and aging. Whereas “MycKO” mice have an extended lifespan because of a lower cancer incidence, “MlxKO” mice have normal lifespans and a somewhat higher cancer incidence. Like Myc, Mlx, MondoA and ChREBP expression and that of their target genes, deteriorate with age in both mice and humans, underscoring the importance of life-long and balanced cross-talk between the two Networks to maintain normal aging.
Project description:Myc, a member of the Myc Network, supervises proliferation, metabolism and ribosomal function. The Mlx Network cross-talks with the Myc Network and regulates overlapping functions. We describe here the consequences of conditional Myc and/or Mlx gene knockouts (KOs) in primary and immortalized murine embryonic fibroblasts (MEFs). MycKO and MycKOxMlxKO “double KO” (DKO) primary MEFs, but not MlxKO MEFs, rapidly growth-arrested and displayed features of aging and senescence. In DKO MEFs, these were transient, indicating that Mlx was necessary to maintain them. KO MEFs deregulated transcripts pertaining to mitochondrial and ribosomal structure and function, cell cycle, aging, senescence and DNA damage. The expression of DNA damage-related proteins was also abnormal. Immortalized KO MEFs remained proliferation-competent but demonstrated differential sensitivities to genotoxic agents. Immortalized MycKO MEFs spontaneously developed tetraploidy that was Mlx-dependent. Different aspects of MEF aging, senescence and DNA damage responses are therefore differentially regulated by the Myc and Mlx Networks.
Project description:The Myc bHLH-ZIP transcription factor is deregulated by most cancers. As a heterodimer with the bHLH-ZIP protein Max, Myc regulates target genes that contribute to metabolism and proliferation. This “Myc Network” cross-talks with the “Mlx Network” comprised of the Myc-like bHLH-ZIP proteins MondoA and ChREBP and the Max-like bHLH-ZIP protein Mlx. This “Extended Myc Network” regulates genes with both common and distinct functions. We have generated hepatocytes lacking Mlx (mlxKO) or Mlx+Myc (double KO or DKO) and quantified their abilities to replace dying hepatocytes in a murine model of Type I tyosinemia. We find that this function deteriorates as the Extended Myc Network is progressively dismantled. Genes dysregulated in mlxKO and DKO hepatocytes include those involved in translation and mitochondrial function. The Myc and Mlx Networks thus cross-talk with the latter playing a disproportionate role. mycKO and mlxKO mice also develop age-dependent non-alcoholic fatty liver disease and mlxKO and DKO mice develop extensive hepatic adenomatosis not observed in wild-type, mycKO, chrebpKO or mycKOxchrebpKO mice. In addition to demonstrating cooperation between the Myc and Mlx Networks, this study reveals the latter to be more important in maintaining metabolic and translational homeostasis, while concurrently serving as a suppressor of benign tumorigenesis.
Project description:Metabolic stress and changes in nutrient levels modulate many aspects of skeletal muscle function during aging and disease. Growth factors and cytokines secreted by skeletal muscle, known as myokines, are important signaling factors but it is largely unknown whether they modulate muscle growth and differentiation in response to nutrients. Here, we find that changes in glucose levels increase the activity of the glucose-responsive transcription factor MLX, which promotes and is necessary for myoblast fusion. MLX promotes myogenesis not via an adjustment of glucose metabolism but rather by inducing the expression of several myokines, including insulin like-growth factor-2 (IGF2), whereas RNAi and dominant-negative MLX reduce IGF2 expression and block myogenesis. This phenotype is rescued by conditioned media from control muscle cells and by recombinant IGF2, which activates the myogenic kinase Akt. Importantly, MLX null mice display decreased IGF2 induction and diminished muscle regeneration in response to injury, indicating that the myogenic function of MLX is conserved in vivo. Thus, glucose is a signaling molecule that regulates myogenesis and muscle regeneration via MLX/IGF2/Akt signaling.â??The data pproided are histome H4 acetlation data for MLX DN and MLX wt samples; 3 MLX DN H4 Ac Chip seq samples , 3 Inputs, 3 MLX WT H4 Ac samples and 3 WT inputs
Project description:This study set out to identify MLX transcriptional targets in muscle cells. C2C12 Myoblasts were virally transduced to increase MLX activity, by overexpression of the wild-type protein; and to decrease MLX activity by overexpression of a dominant negative MLX protein and by shRNA induced knockdown of MLX. Transcripts that were significantly and consistently regulated by the different modes of MLX modulation were identified. The largest proportion of these were genes encoding secreted proteins including growth factors, cytokines and extracellular proteins. We therefore conclude that MLX can regulate myokine transcripts. mRNA profiles from C2C12 muscle cells with increased and decreased MLX activity were examined.
Project description:We generated mice null for MAX-like Protein X (MLX), encoded by Mlx. All male mice are sterile. We profiled testes tissue from WT versus KO mice by RNA-Seq. We performed ChIP-Seq on WT and KO testes for MLX and MAX, as well as ChIP-Seq for MLX and MAX from primary B220+ splenic B cells, and ChIP-Seq for MLX, MAX and MNT from 3T3 cell lines derived from WT and KO embryos.
Project description:Metabolic stress and changes in nutrient levels modulate many aspects of skeletal muscle function during aging and disease. Growth factors and cytokines secreted by skeletal muscle, known as myokines, are important signaling factors but it is largely unknown whether they modulate muscle growth and differentiation in response to nutrients. Here, we find that changes in glucose levels increase the activity of the glucose-responsive transcription factor MLX, which promotes and is necessary for myoblast fusion. MLX promotes myogenesis not via an adjustment of glucose metabolism but rather by inducing the expression of several myokines, including insulin like-growth factor-2 (IGF2), whereas RNAi and dominant-negative MLX reduce IGF2 expression and block myogenesis. This phenotype is rescued by conditioned media from control muscle cells and by recombinant IGF2, which activates the myogenic kinase Akt. Importantly, MLX null mice display decreased IGF2 induction and diminished muscle regeneration in response to injury, indicating that the myogenic function of MLX is conserved in vivo. Thus, glucose is a signaling molecule that regulates myogenesis and muscle regeneration via MLX/IGF2/Akt signaling. The data pproided are histome H4 acetlation data for MLX DN and MLX wt samples;
Project description:This study set out to identify MLX transcriptional targets in muscle cells. C2C12 Myoblasts were virally transduced to increase MLX activity, by overexpression of the wild-type protein; and to decrease MLX activity by overexpression of a dominant negative MLX protein and by shRNA induced knockdown of MLX. Transcripts that were significantly and consistently regulated by the different modes of MLX modulation were identified. The largest proportion of these were genes encoding secreted proteins including growth factors, cytokines and extracellular proteins. We therefore conclude that MLX can regulate myokine transcripts.
Project description:A systematic analysis of super-enhancers identified MLX as a potential oncogene in osteosarcoma. Knockdown of MLX impaired tumor aggressiveness in vitro and in vivo, suggesting oncogenic properties of MLX. Mechanistically, silencing of MLX downregulates SLC7A11, a key gene encoding glutamate/cystine antiporter, to attenuate the uptake of cystine and interrupt the redox balance, leading to ferroptotic cell death. Pharmacological inhibition of SLC7A11 triggered massive ferroptosis and caused impaired tumor growth, providing a promising approach for osteosarcoma treatment.