Category: Assay Development and Screening

1352-C - Muscle Cell Phenotypic Screens to Identify Novel Insulin Sensitizers

Tuesday, February 6, 2018
2:00 PM - 3:00 PM

Under physiological conditions, skeletal muscle is the predominant site of glucose disposal and fuel utilization in humans. Skeletal muscle insulin resistance is the primary defect in the pathogenesis of type 2 diabetes. However, currently there is no anti-diabetic medications directly targeting insulin resistance in skeletal muscle.

Ectopic lipid accumulation has been proposed as the underlying pathogenesis of insulin resistance.  Although insulin resistance can occur independently of intramyocellular lipid (IMCL) level, IMCL content has been considered as a predictor of muscle insulin resistance, and lipid metabolites (diglyceride (DAG) and ceramides) have been shown to directly impair insulin signaling. 

To identify novel insulin sensitizers that can enhance fuel utilization in muscle, we developed two high-throughput phenotypic screen assays to measure triglyceride accumulation (TGA) and Glut4 translocation in muscle cells. We adapted lipidtox stain for detecting TGA in a high-content imaging-based assay in C2C12 myotubes and screened for compounds that may have functional impact to alleviate IMCL overload. The confirmed hit rate was 0.25%.  These TGA inhibitors were further evaluated for their ability to increase Glut4 translocation in a novel engineered C2C12 cell line that overexpresses Glut4. We have identified several compound classes that could increase Glut4 translocation and simultaneously reduce TGA, suggesting that these compounds have a potential to improve glucose uptake and insulin sensitivity.  Interestingly, BET inhibitors, IBET151 and IBET762, were amongst the hit compounds that improved muscle metabolic functions.  To further elucidate mechanism of these epigenetic BET inhibitors in regulation of muscle functions, we performed gene expression analysis of 70 selected genes, and identified changes in multiple genes’ expression associated with improvement of muscle metabolic functions and insulin sensitivity, including Sirt1 and Sesn3. Our data demonstrates that phenotypic screen approaches can effectively identify novel mechanisms to improve muscle metabolic functions with potential to treat type 2 diabetes.   

Yi Yang

Sr. Scientist
Merck & Co.
Boston, MA

Yi Yang has been working at Merck & Co. since 2000. She has extensive knowledge in cell biology, molecular biology and protein biochemistry. She is a Senior Scientist in Cell Pharmacology group at Merck Boston, focusing on cell culture and cell-based screen since 2011. From 2004 to 2011, she worked in Investigative Toxicology department on drug induced toxicity and biomarker identification. From 2000 to 2004, she worked in Cancer Research department focusing on cell-based screens for cell cycle, checkpoint and cell survival Oncology. Prior to joining Merck, Yi Yang worked on protein chemistry at Abramson research center in The Children’s hospital of Philadelphia. Yi Yang got her MS from West China Medical School, Sichuan University, and received advanced training in molecular biology and immunology from Kyushu University, Japan.