Plant-Produced Asialo-Erythropoietin Restores Pancreatic Beta-Cell Function by Suppressing Mammalian Sterile-20-like Kinase (MST1) and Caspase-3 Activation.

Elena Arthur,Jiahua Xie,Yuan Lin,Chiu-Yueh Hung,David C Sane,Farooqahmed S Kittur

doi:10.3389/fphar.2017.00208

Abstract

Pancreatic beta-cell death adversely contributes to the progression of both type I and II diabetes by undermining beta-cell mass and subsequently diminishing endogenous insulin production. Therapeutics to impede or even reverse the apoptosis and dysfunction of beta-cells are urgently needed. Asialo-rhuEPO, an enzymatically desialylated form of recombinant human erythropoietin (rhuEPO), has been shown to have cardioprotective and neuroprotective functions but with no adverse effects like that of sialylated rhuEPO. Heretofore, the anti-apoptotic effect of asialo-rhuEPO on pancreatic beta-cells has not been reported. In the current study, we investigated the cytoprotective properties of plant-produced asialo-rhuEPO (asialo-rhuEPOP) against staurosporine-induced cell death in the pancreatic beta-cell line RIN-m5F. Our results showed that 60 IU/ml asialo-rhuEPOP provided 41% cytoprotection while 60 IU/ml rhuEPO yielded no effect. Western blotting results showed that asialo-rhuEPOP treatment inhibited both MST1 and caspase-3 activation with the retention of PDX1 and insulin levels close to untreated control cells. Our study provides the first evidence indicating that asialo-rhuEPOP-mediated protection involves the reduction of MST1 activation, which is considered a key mediator of apoptotic signaling in beta-cells. Considering the many advantages its plant-based expression, asialo-rhuEPOP could be potentially developed as a novel and inexpensive agent to treat or prevent diabetes after further performing studies in cell-based and animal models of diabetes.

Highlights

Diabetes has evolved into a high priority global epidemic (America’s Biopharmaceutical Research Companies, 2014)
Our study revealed that asialo-rhuEPOP protects pancreatic beta-cells from chemically induced apoptosis by preventing both Mammalian Sterile-20-like Kinase (MST1) and caspase-3 activation with the retention of pancreatic duodenal homeobox-1 (PDX1) and insulin levels similar to untreated control cells
MST1 has been recently discovered as a key mediator of apoptotic signaling in pancreatic beta-cells (Ardestani et al, 2014)

Summary

Introduction

Diabetes has evolved into a high priority global epidemic (America’s Biopharmaceutical Research Companies, 2014). The discovery of new therapeutics, directly targeting the apoptotic process to impede or even reverse beta-cell apoptosis and dysfunction, is urgently needed. In the apoptosis signaling pathway, MST1 acts both as an activator as well as a target of caspase-3 (Figure 1) (Kakeya et al, 1998; Lee et al, 1998; Ardestani et al, 2014). MST1 has been suggested as a target for the discovery of new drugs for diabetes because of its critical role in beta-cell apoptosis and dysfunction (Ardestani et al, 2014). No agent has been identified yet to counteract the apoptotic activity of MST1 for the purpose of promoting beta-cell survival

Methods

Results

Conclusion