Prospection of therapeutic targets and diagnostic methods related to dipeptidyl peptidase iv (DPP-IV) and glucagon-like peptide type 1 receptor (GLP-1R) by using Bothrops jararaca venom

Abstract

Metabolic syndrome is close related to diabetes mellitus type II and visceral obesity, being a serious public health problem. Vildagliptin and sitagliptin, inhibitors of dipeptidyl-peptidase IV (DPP-IV) (EC 3.4.14.5), the enzyme responsible for the cleavage of glucagon-like peptide-1 hormone (GLP-1), as well exenatide, which was developed from Heloderma suspectum lizard venom, and liraglutide, both DPP-IV-resistant GLP-1 agonists, are the most recent pharmacological resources for diabetes mellitus with possible aplicability also to the treatment of obesity. Regarding the close phylogenetic relationship between lizards and snakes, besides that the exenatide has been only evaluated in the mandibular glands of Anguimorpha lizards, and that the cDNA gland library of the snake Bothrops jararaca is already published, pointing out 1154 expressed sequence tags, the present project aims to prospect exenatide-like molecules and DPP-IV inhibitors from peptide fractions of this snake venom. The snake venom will be purified by gel filtration and reverse-phase HPLC. DPP-IV from rat's small intestine and serum will be purified by gel filtration and ion-exchange. SDS polyacrylamide gel electrophoresis will characterize purified DPP-IV. The antigenic similarity with exenatide (Ouchterlony immunodiffusion) and GLP-1 antagonism or agonism (binding to pancreatic GLP-1 receptor) will be searched in venom fractions between 3,.0 to 4.5 kDa. The effects on activity (assays with fluorogenic and chromogenic substrates) of DPP-IV from rat (purified by us) and human (commercially purchased) will be searched in venom fractions between 0.2 to 7.0 kDa and compared to the effects of inhibitors diprotin A, vildagliptin and sitagliptin, and of GLP-1 substrate. This bioprospection will bring light to the composition and biological activities of B. jararaca venom in addition to the possibility to find new pharmacological agents. (AU)