Discovery Of Active Compounds Targeting Potassium Channel Kv2.1and Glucocorticoid Receptor And Investigation An The Related Mechanism

Type2diabetes (T2DM) is a worldwide disease characterized by insulin resistanceand the progressive failure of pancreatic p-cell.丁his thesis maily focuses on thediscovery of active compounds to ameliorate these aspects and investigation on therelated mechanism, which might provid valuable structural information and newstrategies for anti-diabetic drug discovery.Firstly, more and more evidences indicate that pancreatic p cell dysfunction is oneof major causes of type2diabetes. As reported, there have a variety of ion flow inpancreatic p cells, in which voltage-gated potassium channels (Kv), especially Kv2.1,play important roles in the cell membrane repolarization and act as negative regulatorin glucose-stimulated insulin secretion. Apart from this, Kv2.1inhibitors currently arediscovered to protect pancreatic (i cells from STZ-induced cell apoptosis. Therefore,Kv2.1potassium channel may be a potential target which can both promote insulinsecretion and protect p cells from apotosis. In the course of our exploration of Kv2.linhibitor, high throughput fluorescent screening platform of membrane potential wasfirstly constructed and two Kv2.1inhibitors (SP6616and SP3827) were screen outfrom7031compounds with dual-effects on the promotion of insulin secretion andprotection of p cells from STZ-induced cell apoptosis. Consistented with the literature,the effects of SP6616and SP3827on promoting insulin secretion were associatedwith C2a+influx independent on Kv2‘l closure. Since the related signal pathwaysinvolved in Kv2.1protecting p cells from apotosis has not yet been clarified, theunderlying mechanism of SP6616in cell protection were investigated. We firstlyfound that both PKC/Erkl/2and Akt pathways were involved in the protectivefunction of SP6616for P cells. Then the assays on the model of type2diabetic miceinduced by high-fat diet (HFD) combined with STZ (STZ/HFD) and db/db transgenicmice demonstrated that SP6616administration efficiently decreased fasting bloodglucose and glyctcd haemoglobin (HbA ic) level, improved oral glucose tolerance andincreased serum insulin level. Similarly，SP3827also decreased the fasting bloodglucose and glycted haemoglobin (HbA1c) level, improved oral glucose tolerance andincreased serum insulin level in the STZ/HFD model. Therefore, our current work has highlighted the potential of Kv2.1in anti-hyperglycemia research and the discovery ofSP6616and SP3827might supply lead compounds for anti-daibetic drugdevelopment.Secondly，insulin resistance is another characteristic feature of type2diabetes.Modern lifestyle with abundant nutrient supply has resulted in a sharp and rapidincreas in obesity, and the inflammation produced by obesity is very important in theonset of insulin resistance. As known, glucocorticoids are widely used asanti-inflammatory drugs，but their side effects are more common in patients whichmainly produced by transcriptional activation of glucocorticoid receptor (GR). So thediscovery of new glucocorticoid receptor modulators with little adverse effects isanother direction for the treatment of T2DM. In the course of our exploration of GRmodulator, GR translocation platform was constructed based on Incell Analyzer1000in the stable cell strains GFP-GR-U20S, where SP2602and SP4267with effects onpromting GR translocate to nucleus were selected. Moreover, they could obviouslyinhibit the transcriptional activity of AP-1, whereas had no effect on thetranscriptional activity of GR. Then SP2602was further discovered to significantlyreduce the LPS-induced inflammatory cytokines, like TNF-a and IL-6. mRNA levelsin HepG2, which illustrated that this GR modulator had anti-inflammatory effect andmight be developed as a lead compound for anti-daibetic drug development.In conclusion, we found two Kv2.1inhibitors with dual-effects on the promotion ofinsulin secretion and protection of pancreatic p cells from STZ-induced cell apoptosisand a glucocorticoid receptor modulator with anti-inflammatory effect, which mightprovide valuable lead compounds for the treatment of type2diabetes.