Polypeptide from Chlamys farreri restores endoplasmic reticulum (ER) redox homeostasis, suppresses ER stress, and inhibits ER stress-induced apoptosis in ultraviolet B-irradiated HaCaT cells

摘要

Objective: To investigate the effects of polypeptide from Chlamys farreri (PCF) on ultraviolet B (UVB)-induced apoptosis in human keratinocyte HaCaT cells. Methods: In HaCaT cells at 4 h or 18 h after UVB irradiation, the cell viability was measured by MTT assay. Cellular apoptosis was detected with annexin V-FITC/PI staining by flow cytometry. The expression levels of PDI, Ero-1α, GRP78, and CHOP were assessed by Western blot analysis. Mitochondrial membrane potential (MMP) was measured by fluorescent probe JC-1. Caspase activities were detected with fluorogenic substrates. Results: PCF alleviated cell viability loss and inhibited apoptosis in HaCaT cells after UVB irradiation. Moreover, PCF increased the expression levels of PDI and Ero-1α, which were related with the ER redox homeostasis. Furthermore, PCF treatment inhibited the expression of GRP78 at 4 h after UVB irradiation, and suppressed CHOP expression at 18 h post-irradiation, indicating that PCF could inhibit UVB-evoked ER stress in the early stage post-irradiation, and suppress the ER stress-induced apoptosis in the late stage. In addition, PCF alleviated UVB-induced MMP loss, and inhibited the activation of caspase-9/-3, in HaCaT cells after UVB irradiation. On the other hand, MMP loss and caspase-9/-3 activation could be partly blocked by the ER stress inhibitor 4-PBA. Conclusions: PCF inhibits UVB-induced apoptosis through restoring ER redox homeostasis, suppressing ER stress, and inhibiting ER stress-induced mitochondrial apoptosis in HaCaT cells. These findings provide evidence for the mechanism underlying UVB-induced skin damages, and support the promising role of PCF in treatment of the diseases.