ORMDL3 Facilitates the Survival of Splenic B Cells via an ATF6α-Endoplasmic Reticulum Stress-Beclin1 Autophagy Regulatory Pathway.

The genetic association of orosomucoid-like 3 (ORMDL3) with an array of immunoinflammatory disorders has been recently unraveled in multiple ethnic groups, and functional exploration has received attention of the particular relevance of this gene in endoplasmic reticulum stress, lipid metabolism, and inflammatory response. In this study, we demonstrated the upregulation of ORMDL3 in both patients with systemic lupus erythematosus and lupus mice compared with controls. By establishing ORMDL3 knockout mice (Ormdl3-/-), we showed that silencing Ormdl3 in vivo significantly decreased the proportions of mature B lymphocytes and transitional 2B cells in spleen and B1a cells from abdominal cavity perfusion fluid, the secretion of IgG and IgM, and the expression of Baff. Additionally, knockdown of Ormdl3 augmented the apoptosis of total splenic cells and splenic CD19+ B cells but did not affect B cell proliferation and cell cycle. Subsequently, we in vitro and in vivo demonstrated that ORMDL3 potentially mediates the autophagy via the ATF 6-Beclin1 autophagy pathway, and it facilitates the survival of splenic B cells via promoting autophagy and suppressing apoptosis. Taken together, we uncovered a role of ORMDL3 in fine-tuning B cell development and survival, besides highlighting a potential mechanism by which ORMDL3 regulates autophagy via ATF6 pathway.