Endoplasmic reticulum protein 29 is involved in endoplasmic reticulum stress in islet beta cells.

Endoplasmic reticulum stress (ERS) is correlated with insulin resistance and islet‑cell function. In the present study, the sub‑cellular localization and role of ER protein 29 (Erp29) were investigated in an in vitro ERS model of islet beta cells. The INS‑1 islet cell line was treated with various concentrations of tunicamycin to establish the ERS model. Immunofluorescence microscopy demonstrated that Erp29 and anti‑ER marker protein calnexin were co‑localized in NIH3T3 cells, suggesting that Erp29 is localized to the ER. The ERS model induced by tunicamycin showed significantly increased expression of binding immunoglobulin protein (BIP)/glucose‑regulated protein 78 (Grp78), which is a marker for ERS, and the expression of Erp29 was also increased at the mRNA and protein levels. Of note, ERS was blocked following small interfering RNA‑mediated silencing of Erp29 expression, as indicated by reduced BIP/Grp78 expression. As an ER protein, Erp29 may have an important role in ERS in islet beta cells.