Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from Mus musculus tissues (Heart, Liver, Lung, Kidney, Skeletal Muscle, Thymus)
Project description:Activation of the sympathetic nervous system causes pronounced metabolic changes that are mediated by multiple adrenergic receptor subtypes. Systemic treatment with β<sub>2-</sub>adrenergic receptor agonists results in multiple beneficial metabolic effects, including improved glucose homeostasis. To elucidate the underlying cellular and molecular mechanisms, we chronically treated wild-type mice and several newly developed mutant mouse strains with clenbuterol, a selective β<sub>2</sub>-adrenergic receptor agonist. Clenbuterol administration caused pronounced improvements in glucose homeostasis and prevented the metabolic deficits in mouse models of β-cell dysfunction and insulin resistance. Studies with skeletal muscle-specific mutant mice demonstrated that these metabolic improvements required activation of skeletal muscle β<sub>2</sub>-adrenergic receptors and the stimulatory G protein, G<sub>s</sub>. Unbiased transcriptomic and metabolomic analyses showed that chronic β<sub>2</sub>-adrenergic receptor stimulation caused metabolic reprogramming of skeletal muscle characterized by enhanced glucose utilization. These findings strongly suggest that agents targeting skeletal muscle metabolism by modulating β<sub>2</sub>-adrenergic receptor-dependent signaling pathways may prove beneficial as antidiabetic drugs.
Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from seven Mus musculus tissues (Heart, Brain, Liver, Lung, Kidney, Skeletal Muscle, Thymus)
Project description:Translational research is commonly performed in the C57B6/J mouse strain, chosen for its genetic homogeneity and phenotypic uniformity. Here, we evaluate the suitability of the white-footed deer mouse (Peromyscus leucopus) as a model organism for aging research, offering a comparative analysis against C57B6/J and diversity outbred (DO) Mus musculus strains. Our study includes comparisons of body composition, skeletal muscle function, and cardiovascular parameters, shedding light on potential applications and limitations of P. leucopus in aging studies. Notably, P. leucopus exhibits distinct body composition characteristics, emphasizing reduced muscle force exertion and a unique metabolism, particularly in fat mass. Cardiovascular assessments showed changes in arterial stiffness, challenging conventional assumptions and highlighting the need for a nuanced interpretation of aging-related phenotypes. Our study also highlights inherent challenges associated with maintaining and phenotyping P. leucopus cohorts. Behavioral considerations, including anxiety-induced responses during handling and phenotyping assessment, pose obstacles in acquiring meaningful data. Moreover, the unique anatomy of P. leucopus necessitates careful adaptation of protocols designed for Mus musculus. While showcasing potential benefits, further extensive analyses across broader age ranges and larger cohorts are necessary to establish the reliability of P. leucopus as a robust and translatable model for aging studies.
Project description:Background: Beta-adrenergic receptor agonists (BA) induce skeletal muscle hypertrophy, yet specific mechanisms that lead to this effect are not well understood. The objective of this research was to identify novel genes and physiological pathways that potentially facilitate BA induced skeletal muscle growth. We chose to evaluate global changes in gene expression by utilizing the Affymetrix platform to identify gene expression changes in mouse skeletal muscle. Changes in gene expression were evaluated 24 h (1D) and 10 days (10D) after administration of the BA clenbuterol. Results: Administration of clenbuterol stimulated anabolic activity, as indicated by decreased blood urea nitrogen (BUN; P < 0.01) and increased body weight gain (P < 0.05) 24 h or 10 d, respectively, after initiation of clenbuterol treatment. A total of 22,787 probesets were evaluated with 113 probesets defined as differentially expressed based on a false discovery rate of 10%. Differential mRNA abundance of four of these genes was validated in an independent experiment by quantitative PCR. Patterns of gene expression change observed from the microarray data suggested more genes are differentially regulated after 24 h than 10 d of BA administration. Functional characterization of differentially expressed genes revealed several categories that participate in biological processes important to skeletal muscle growth, including regulators of transcription and translation, mediators of cell-signaling pathways, and genes involved in polyamine metabolism. Included within these lists were several genes previously associated with myogenic differentiation, along with multiple genes known to promote a general up-regulation of translation. Conclusions: Global evaluation of gene expression after administration of clenbuterol identified changes gene expression and overrepresented functional categories of genes that may regulate BA-induced muscle hypertrophy. Changes in the mRNA abundance of multiple genes associated with myogenic differentiation may indicate an important effect of BA on the proliferation, differentiation, and/or recruitment of satellite cells into muscle fibers to promote muscle hypertrophy. Additionally, increased mRNA abundance of genes involved in the initiation of translation suggests that increased levels of protein synthesis often associated with BA administration may result from a general up-regulation of translational initiators, rather than a sustained up-regulation of gene expression at the transcriptional level. Additionally, numerous other genes and physiological pathways were identified that will be important targets for further investigations of the hypertrophic effect of BA on skeletal muscle. Experiment Overall Design: A total of 27 mice were used to represent three treatments. Hybridizations were done using RNA pools from 3 mice, with 3 pools (replicates) per treatment. Treatments included control, 1 day of clenbuterol administration, and 10 days of clenbuterol administration. Data represent skeletal muscle gene expression.
Project description:Clenbuterol-HCL can greatly reduce fat deposition and increase skeletal muscle growth at high dosages. In order to advance our understanding of the fundamental molecular mechanisms, Genechips were used to study the differential gene expression profiles of liver tissues among the pigs with/without Clenbuterol-HCL. Differentially expressed genes identified will be the candidates for further investigations on the molecular mechanisms involved in Clenbuterol-HCL of exerting repartition effects on adipose and skeletal muscle tissue.
Project description:We analyzed the functional role of DOR (Diabetes and Obesity Regulated gene) (also named Tp53inp2) in skeletal muscle. We show that DOR has a direct impact on skeletal muscle mass in vivo. Thus, using different transgenic mouse models, we demonstrate that while muscle-specific DOR gain-of-function results in reduced muscle mass, loss-of-function causes muscle hypertrophy. DOR has been described as a protein with two different functions, i.e., a nuclear coactivator and an autophagy regulator (Baumgartner et. al., PLoS One, 2007; Francis et. al., Curr Biol, 2010; Mauvezin et. al., EMBO Rep, 2010; Nowak et. al., Mol Biol Cell, 2009). This is why we decided to analyze which of these two functions could explain the phenotype observed in our mice models. In this regard, we performed a transcriptomic analysis using microarrays looking for genes differentially expressed in the quadriceps muscle of WT and SKM-Tg mice as well as in C and SKM-KO animals. Surprisingly, only a reduced number of genes were dysregulated upon DOR manipulation and most of the genes underwent mild changes in expression. These data strongly suggest that DOR does not operate as a nuclear co-factor in mouse skeletal muscle under the conditions subjected to study. In contrast, DOR enhances basal autophagy in skeletal muscle and promotes muscle wasting when autophagy is a contributor to muscle loss. To determine the functional role of DOR in skeletal muscle, we generated transgenic mice (SKM-Tg) overexpressing DOR specifically in skeletal muscle under the Myosin-Light Chain 1 promoter/enhancer. The open reading frame of DOR was introduced in an EcoRI site in the MDAF2 vector, which contains a 1.5 kb fragment of the MLC1 promoter and 0.9 kb fragment of the MLC1/3 gene containing a 3' muscle enhancer element (Rosenthal et. al., PNAS, 1989; Otaegui et. al., FASEB J, 2003). The fragment obtained after the digestion of this construct with BssHII was the one used to generate both transgenic mouse lines. Nontransgenic littermates were used as controls for the transgenic animals (Wt). In addition, a muscle-specific DOR knock-out mouse line (SKM-KO) was also generated by crossing homozygous DOR loxP/loxP mice with a mouse strain expressing Cre recombinase under the control of the Myosin-Light Chain 1 promoter (Bothe et. al., Genesis, 2000). Deletion of exons 3 and 4 driven by Cre recombinase caused the ablation of DOR expression. Non-expressing Cre DOR loxP/loxP littermates were used as controls for knockout animals (C). Four-month-old male mice were used in all experiments. Mice were in a C57BL/6J pure genetic background.
Project description:We analyzed the functional role of DOR (Diabetes and Obesity Regulated gene) (also named Tp53inp2) in skeletal muscle. We show that DOR has a direct impact on skeletal muscle mass in vivo. Thus, using different transgenic mouse models, we demonstrate that while muscle-specific DOR gain-of-function results in reduced muscle mass, loss-of-function causes muscle hypertrophy. DOR has been described as a protein with two different functions, i.e., a nuclear coactivator and an autophagy regulator (Baumgartner et. al., PLoS One, 2007; Francis et. al., Curr Biol, 2010; Mauvezin et. al., EMBO Rep, 2010; Nowak et. al., Mol Biol Cell, 2009). This is why we decided to analyze which of these two functions could explain the phenotype observed in our mice models. In this regard, we performed a transcriptomic analysis using microarrays looking for genes differentially expressed in the quadriceps muscle of WT and SKM-Tg mice as well as in C and SKM-KO animals. Surprisingly, only a reduced number of genes were dysregulated upon DOR manipulation and most of the genes underwent mild changes in expression. These data strongly suggest that DOR does not operate as a nuclear co-factor in mouse skeletal muscle under the conditions subjected to study. In contrast, DOR enhances basal autophagy in skeletal muscle and promotes muscle wasting when autophagy is a contributor to muscle loss. To determine the functional role of DOR in skeletal muscle, we generated transgenic mice (SKM-Tg) overexpressing DOR specifically in skeletal muscle under the Myosin-Light Chain 1 promoter/enhancer. The open reading frame of DOR was introduced in an EcoRI site in the MDAF2 vector, which contains a 1.5 kb fragment of the MLC1 promoter and 0.9 kb fragment of the MLC1/3 gene containing a 3' muscle enhancer element (Rosenthal et. al., PNAS, 1989; Otaegui et. al., FASEB J, 2003). The fragment obtained after the digestion of this construct with BssHII was the one used to generate both transgenic mouse lines. Nontransgenic littermates were used as controls for the transgenic animals (Wt). In addition, a muscle-specific DOR knock-out mouse line (SKM-KO) was also generated by crossing homozygous DOR loxP/loxP mice with a mouse strain expressing Cre recombinase under the control of the Myosin-Light Chain 1 promoter (Bothe et. al., Genesis, 2000). Deletion of exons 3 and 4 driven by Cre recombinase caused the ablation of DOR expression. Non-expressing Cre DOR loxP/loxP littermates were used as controls for knockout animals (C). Four-month-old male mice were used in all experiments. Mice were in a C57BL/6J pure genetic background. We used microarrays to analyze the effect of DOR gain-of-function and DOR ablation on skeletal muscle gene expression Total RNA from quadriceps muscles from 4-month-old male mice was extracted and used for hibridization on Affimetrix microarrays
Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from Mus musculus tissues (Heart, Liver, Lung, Kidney, Skeletal Muscle, Thymus)