Role of HSP lysine methylation in Type 2 diabetes mellitus (T2DM)

Abstract

Type 2 diabetis mellitus (T2DM) affects approximately 3% in most European countries but a staggering 10% of the adult population in Malta. This significantly high prevalence of T2DM in Malta results in nearly 25% of deaths under the age of 65, mainly through cardiovascular complications. Overall T2DM costs European countries roughly 5% of their total yearly healthcare expenditure. While several studies have been devoted to the evaluation of genetic factors related to T2DM and associated complications, much less is known about the role played by post-translational modifications (PMTs) of proteins as the disease progresses or that occur as a result of aging or other environmental factors, without any DNA mutations. Evidence gathered so far indicates that some lysine methyltransferases (KMTs) are unique in their targets and biological roles and among these is a METTL group of S-adenosyl-methionine-dependent methyltransferases specific to chaperones. These enzymes show great potential towards affecting some processes in T2DM. To investigate this issue, a custom sandwich ELISA has been designed to allow for the testing of presence and quantification of lysine methylation on delected Heat Shock Proteins (HSPs) in the serum of diabetics. In this set up, the HSP-specific antibody is attached to the plate and the sandwich antibody used, specific for the selected PTM, is antimethyl-lysine. This is then probed by anti-rabbit horseradish peroxidase conguage, which converts a blue substrate to yellow if the target HSP is present and the amount of dye ca be easily quantified using a Mithras LB940 microplate reader. In the initial phase of this study, the serum samples obtained from consenting male diabetics or healthy controls are being screened for methylated lysines on HSP27, HSP60, HSP70, HSP90 and GRP78.