Biochemical Properties of CARM1: Impact on Western\nBlotting and Proteomic Studies

CARM1 is an arginine\nmethyltransferase that has crucial roles in\na number of cellular pathways and is being explored as a therapeutic\ntarget in diseases such as cancer and neurodegenerative disorders.\nIts deregulation at the protein level was found to have potential\nprognostic value, and as such, its protein levels are regularly assessed\nthrough the common practice of western blotting (WB). Our group uncovered\nthat CARM1 has biochemical properties that complicate its analysis\nby standard WB sample preparation techniques. Here, we show that CARM1\nhas the ability to form SDS-resistant aggregates that effectively\nhinder gel migration in SDS-PAGE. CARM1 levels and the temperature\nat the denaturation step can both influence CARM1 aggregation, which\nprompts the use of additional measures to ensure representative detection\nat the protein level. We have demonstrated the formation of CARM1\naggregates in both cell and tissue extracts, making these findings\nan important consideration for any CARM1-related study. We also show\nhow aggregate formation in models of CARM1 overexpression can hinder\nproteomic studies. Having identified factors that can induce CARM1\naggregation, we suggest alternative sample preparation techniques\nthat allow for clear resolution of the protein in stringent denaturing\nconditions while avoiding aggregation.