Proteomics insights into the effects of MSTN on muscle glucose and lipid metabolism in genetically edited cattle.

The molecular mechanism underlying myostatin (MSTN)-regulated metabolic cross-talk remains poorly understood. In this study, we performed comparative proteomic and phosphoproteomic analyses of gluteus muscle tissues from MSTN-/- transgenic cattle using a shotgun-based tandem mass tag (TMT) 6-plex labeling method to explore the signaling pathway of MSTN in metabolic cross-talk and cellular metabolism during muscle development. A total of 72 differentially expressed proteins (DEPs) and 36 differentially expressed phosphoproteins (DEPPs) were identified in MSTN-/- cattle compared to wild-type cattle. Bioinformatics analyses showed that MSTN knockout increased the activity of many key enzymes involved in fatty acid ß-oxidation and glycolysis processes in cattle. Furthermore, comprehensive pathway analyses and hypothesis-driven AMP-activated protein kinase (AMPK) activity assays suggested that MSTN knockout triggers the activation of AMPK signaling pathways to regulate glucose and lipid metabolism by increasing the AMP/ATP ratio. Our results shed new light on the potential regulatory mechanism of MSTN associated with metabolic cross-talk in muscle development, which can be used in animal breeding to improve meat production in livestock animals, and can also provide valuable insight into treatments for obesity and diabetes mellitus in humans.

Parallel comparative proteomics and phosphoproteomics reveal that cattle myostatin regulates phosphorylation of key enzymes in glycogen metabolism and glycolysis pathway.

MSTN-encoded myostatin is a negative regulator of skeletal muscle development. Here, we utilized the gluteus tissues from MSTN gene editing and wild type Luxi beef cattle which are native breed of cattle in China, performed tandem mass tag (TMT) -based comparative proteomics and phosphoproteomics analyses to investigate the regulatory mechanism of MSTN related to cellular metabolism and signaling pathway in muscle development. Out of 1,315 proteins, 69 differentially expressed proteins (DEPs) were found in global proteomics analysis. Meanwhile, 149 differentially changed phosphopeptides corresponding to 76 unique phosphorylated proteins (DEPPs) were detected from 2,600 identified phosphopeptides in 702 phosphorylated proteins. Bioinformatics analyses suggested that majority of DEPs and DEPPs were closely related to glycolysis, glycogenolysis, and muscle contractile fibre processes. The global discovery results were validated by Multiple Reaction Monitoring (MRM)-based targeted peptide quantitation analysis, western blotting, and muscle glycogen content measurement. Our data revealed that increase in abundance of key enzymes and phosphorylation on their regulatory sites appears responsible for the enhanced glycogenolysis and glycolysis in MSTN-/- . The elevated glycogenolysis was assocaited with an enhanced phosphorylation of Ser1018 in PHKA1, and Ser641/Ser645 in GYS1, which were regulated by upstream phosphorylated AKT-GSK3ß pathway and highly consistent with the lower glycogen content in gluteus of MSTN-/- . Collectively, this study provides new insights into the regulatory mechanisms of MSTN involved in energy metabolism and muscle growth.

Comparative muscle proteomics/phosphoproteomics analysis provides new insight for the biosafety evaluation of fat-1 transgenic cattle.

The biosafety of fat-1 transgenic cattle has been a focus of our studies since the first fat-1 transgenic cow was born. In this study, we used tandem mass tag labeling, TiO2 enrichment, and nanoscale liquid chromatography coupled with tandem mass spectrometry (nanol LC-MS/MS) to compare proteomic and phosphoproteomic profiling analyses of muscle between fat-1 transgenic cows and wild-type cows. A total of 1555 proteins and 900 phosphorylation sites in 159 phosphoproteins were identified in the profiling assessments, but only four differentially expressed proteins and nine differentially expressed phosphopeptides were detected in fat-1 transgenic cows relative to wild-type cows. Bioinformatics analyses showed that all of the identified proteins and phosphoproteins were mainly related to the metabolic processes of three major nutrients: carbohydrates, lipids, and proteins. All of these differentially expressed proteins might take part in DNA recombination, repair, and regulation of the immune system. In conclusion, most of the identified proteins and phosphoproteins exhibited few changes. Our results provide new insights into the biosafety of fat-1 transgenic cattle.

A yeast two-hybrid assay reveals CMYA1 interacting proteins.

CMYA1 is a protein that plays an important role in muscle development and contains a highly conserved Xin repeats region. However, the function of the Xin-repeats in CMYA1 is unknown, and there is little information regarding proteins that interact with the CMYA1/Xin-repeats in the bovine system. In this study, we generated a high-quality bovine muscle cDNA library and performed a yeast two-hybrid screen twice using both CMYA1 and the Xin-repeats as bait. There were 27 candidate-interacting proteins identified in this screen. Three of the 27 proteins (RPL35A, RPL21 and EIF3G) interacted with both CMYA1 and the Xin-repeats, and this interaction was further confirmed using one-to-one Y2H mating. These results showed that the three candidate proteins interacted with CMYA1/Xin-repeats and indicated that the Xin-repeats is a key region of CMYA1 required for protein interaction. In conclusion, our results provide new targets on the bovine CMYA1/Xin-repeats interacting proteins, and these findings provide an important reference for the study of how bovine muscle development is regulated.