TAT-C1aB

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes severely afflicting the patients, while there is yet no effective medication against this disease. As Kv2.1 channel functions potently in regulating neurological disorders, the present work was to investigate the regulation of Kv2.1 channel against DPN-like pathology of DPN model mice by using selective Kv2.1 inhibitor SP6616 (ethyl 5-(3-ethoxy-4-methoxyphenyl)-2-(4-hydroxy-3-methoxybenzylidene)-7-methyl-3-oxo-2,3-dihydro-5H-[1,3]thiazolo[3,2-a]pyrimidine-6-carboxylate) as a probe.

STZ-induced type 1 diabetic mice with DPN (STZ mice) were defined at 12 weeks of age (4 weeks after STZ injection) through behavioral tests, and db/db (BKS Cg-m^+/+Lepr^db/J) type 2 diabetic mice with DPN (db/db mice) were at 18 weeks of age. SP6616 was administered daily via intraperitoneal injection for 4 weeks. The mechanisms underlying the amelioration of SP6616 on DPN-like pathology were investigated by RT-PCR, western blot and immunohistochemistry technical approaches against diabetic mice, and verified against the STZ mice with Kv2.1 knockdown in dorsal root ganglion (DRG) tissue by injection of adeno associated virus AAV9-Kv2.1-RNAi. Amelioration of SP6616 on the pathological behaviors of diabetic mice was assessed against tactile allodynia, thermal sensitivity and motor nerve conduction velocity (MNCV).

SP6616 treatment effectively ameliorated the threshold of mechanical stimuli, thermal sensitivity and MNCV of diabetic mice. Mechanism research results indicated that SP6616 suppressed Kv2.1 expression, increased the number of intraepidermal nerve fibers (IENFs), improved peripheral nerve structure and vascular function in DRG tissue. In addition, SP6616 improved mitochondrial dysfunction through Kv2.1/CaMKKβ/AMPK/PGC-1α pathway, repressed inflammatory response by inhibiting Kv2.1/NF-κB signaling and alleviated apoptosis of DRG neuron through Kv2.1-mediated regulation of Bcl-2 family proteins and Caspase-3 in diabetic mice.

Our work has highly supported the beneficial of Kv2.1 inhibition in ameliorating DPN-like pathology and highlighted the potential of SP6616 in the treatment of DPN.

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The Kv2.1 channel plays an important role in the regulation against pancreatic β‐cell dysfunctions. Therefore, it is regarded as a promising target for drug discovery against type 2 diabetes. In the present study, we found that the small molecule 4‐ethoxy‐N‐{[6‐(2‐thienyl)‐7H‐[1,2,4]triazolo[3,4‐b][1,3,4]thiadiazin‐3‐yl]methyl}aniline (ETA), a novel Kv2.1 inhibitor, may be capable of promoting glucose‐stimulated insulin secretion and protecting from apoptosis in pancreatic INS‐832/13 cells. The assay of ETA on type 2 diabetic mice induced by high‐fat diet (HFD)/streptozocin (STZ) confirmed its potency in ameliorating glucose homeostasis. ETA administration reduced fasting blood glucose and glycated haemoglobin levels, improved oral glucose tolerance, and increased serum insulin levels in HFD/STZ mice. Mechanism study demonstrated that ETA protected INS‐832/13 cells involving the regulation against protein kinase B and extracellular‐regulated protein kinase 1/2 signalling pathways. Our study has confirmed the underlying regulation of Kv2.1 against β‐cell function and also addressed the potential of ETA as a lead compound in the treatment of type 2 diabetes mellitus.