ReviewIxeris dentata-induced regulation of amylase synthesis and secretion in glucose-treated human salivary gland cells

- Transient exposure of HSG cells to a high concentration of glucose increases amylase synthesis and secretion.
- While chronic exposure to a high concentration of glucose changes the ER environment of cells.
- IXD extract and ID-57D enhance expression of the oxidative protein folding response and secretion of amylase.
- IXD extract and ID-57D reduce ER stress during chronic exposure to a high concentration of glucose.
- IXD extract can increase amylase secretion, highlighting its potential therapeutic value in diabetes or xerostomia treatment.

The endoplasmic reticulum (ER) is an organelle which controls synthesis of secretory and membrane proteins. Alterations in protein folding capacity, leading to ER stress, can be observed in patients with diabetes and related diseases such as xerostomia. The objectives of this study were to investigate the effects of Ixeris dentata (IXD) extract, which has been used for diabetes treatment, and compounds purified from IXD, 8-epidesacylcynaropicrin-3-O-beta-glucopyranoside (ID-57D), on amylase synthesis and secretion in human salivary gland (HSG) cells exposed to a high concentration of glucose. A high concentration of glucose in the experimental medium of cultured cells can model diabetes in vitro. IXD extracts and ID-57D increased oxidative folding-associated protein expression, including p-IRE-1α, PDI and ERO-1α, with the enhanced oxidative folding pattern seen in HSG cells transiently exposed to a high concentration of glucose. Moreover, the treatments reduced the ER stress response, such as the expression of GRP78, maintaining amylase synthesis and secretion in chronically glucose-exposed HSG cells. This study suggests the potential therapeutic value of IXD extract for the treatment of diabetes or its complications such as xerostomia.