Impact of GADD34 on Apoptosis of Tonsillar Mononuclear Cells from IgA Nephropathy Patients by Regulating Eif2α Phosphorylation

Abstract

Background/Aims: Tonsillectomy may be an important method to achieve a long-term remission of IgAN, but patients’ physical status may limit their access to this surgery. We proposed an encouraging solution through inhibiting GADD34 expression in order to promote tonsillar mononuclear cells (TMCs) apoptosis and reduce nephropathic IgA secretion. Methods: A total of 12 IgAN and 9 non-IgAN patients were involved from March 2015 to May 2016. After TMCs were extracted by density gradient centrifugation and stimulated by inactivated hemolytic streptococcus, the mRNA and protein expression of GADD34, GRP78, CHOP, Bcl-2, Bcl-XL, AID, Iα-Cα, and cleaved caspase-3 were examined by fluorescent RT-PCR and Western blotting. Guanabenz treatment and siRNA interference were applied to downregulate GADD34 in tonsillar mononuclear cells from IgAN patients, and P-eIF2α expression was examined by Western Blotting. Cell apoptosis was evaluated by Annexin V FITC/PI flowcytometry, and IgA secretion in cultural supernatant was inspected by enzyme linked immunosorbent assay. Results: After stimulation, the expression of GADD34 was significantly increased in IgAN patients (P< 0.05). Cell apoptosis was mitigated and IgA secretion level was elevated (P< 0.05). To be noticed, CHOP expression had no significant difference between two groups. After guanabenz treatment and siRNA interference, a prolonged elevation of P-eIF2α expression was observed. Cell apoptosis was reinforced and IgA secretion level was decreased (P< 0.05). Conclusion: GADD34 may be a potential therapeutic target for IgAN treatment due to its effect on cell apoptosis.

Keywords

• IgA nephropathy
• Tonsillar mononuclear cell
• ER stress
• GADD34
• Cell apoptosis