Abstract
Oligomerization of human islet amyloid polypeptide (hIAPP) is toxic and contributes to progressive reduction of β cell mass in patients with type 2 diabetes mellitus. Autophagy is a highly conserved homeostatic mechanism in eukaryotes. Previous studies have confirmed that hIAPP can promote autophagy in β cells, but the underlying molecular mechanism and cellular regulatory pathway of hIAPP‑induced autophagy remains not fully elucidated. Accumulation of reactive oxygen species (ROS) causes hIAPP induced‑β cell death. At present, little is known about the association between hIAPP‑induced oxidative stress and autophagy in β cells. Therefore, the present study investigated the underlying molecular mechanism and regulatory pathway of hIAPP‑induced autophagy. Transmission electron microscopy was used to observe the number of autophagosome in cells. Cell viability was determined by an MTT test. A 2',7'‑dichlorofluorescin diacetate assay was used to measure the relative levels of reactive ROS. Western blotting was used to detect expression of adenosine monophosphate‑activated protein kinase (AMPK) and autophagic markers p62 and microtubule associated protein 1 light chain 3. The results demonstrated that hIAPP induces autophagy through ROS‑mediated AMPK signaling pathway in INS‑1 cells. Upregulation of autophagy by AMPK activator 5‑aminoimidazole‑4‑carboxamide1‑β‑D‑ribofuranoside decreased ROS and malondialdehyde generation, whereas inhibition of autophagy by 3‑methyladenine and AMPK inhibitor compound C aggravated hIAPP‑induced oxidative stress and toxicity in INS‑1 cells. Taken together, the present study suggested that hIAPP induces autophagy via a ROS‑mediated AMPK signaling pathway. Furthermore, autophagy serves as a cell‑protective mechanism against hIAPP‑induced toxicity and chemical promotion of autophagy through AMPK signaling pathway attenuates hIAPP induced cytotoxicity and oxidative stress in INS‑1 cells.