Diabetes Research Envisioned and Accomplished in Manitoba (DREAM) Theme, Children's Hospital Research Institute of Manitoba, Winnipeg, Manitoba, Canada.
Department of Pharmacology & Therapeutics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada.
FASEB J. 2021 Dec;35(12):e22023. doi: 10.1096/fj.202100811RR.
B lymphocytes are responsible for humoral immunity and play a key role in the immune response. Optimal mitochondrial function is required to support B cell activity during activation. We examined how deficiency of tafazzin, a cardiolipin remodeling enzyme required for mitochondrial function, alters the metabolic activity of B cells and their response to activation by lipopolysaccharide in mice. B cells were isolated from 3-month-old wild type or tafazzin knockdown mice and incubated for up to 72 h with lipopolysaccharide and cell proliferation, expression of cell surface markers, secretion of antibodies and chemokines, proteasome and immunoproteasome activities, and metabolic function determined. In addition, proteomic analysis was performed to identify altered levels of proteins involved in survival, immunogenic, proteasomal and mitochondrial processes. Compared to wild type lipopolysaccharide activated B cells, lipopolysaccharide activated tafazzin knockdown B cells exhibited significantly reduced proliferation, lowered expression of cluster of differentiation 86 and cluster of differentiation 69 surface markers, reduced secretion of immunoglobulin M antibody, reduced secretion of keratinocytes-derived chemokine and macrophage-inflammatory protein-2, reduced proteasome and immunoproteasome activities, and reduced mitochondrial respiration and glycolysis. Proteomic analysis revealed significant alterations in key protein targets that regulate cell survival, immunogenicity, proteasomal processing and mitochondrial function consistent with the findings of the above functional studies. The results indicate that the cardiolipin transacylase enzyme tafazzin plays a key role in regulating mouse B cell function and metabolic activity during activation through modulation of mitochondrial function.
B 淋巴细胞负责体液免疫，在免疫反应中发挥关键作用。B 细胞活化过程中需要最佳的线粒体功能来支持其活性。我们研究了心磷脂重塑酶 tafazzin 缺乏如何改变 B 细胞的代谢活性及其对脂多糖激活的反应，tafazzin 是一种线粒体功能所必需的酶。从小鼠中分离出 3 个月大的野生型或 tafazzin 敲低 B 细胞，并在脂多糖和细胞增殖、细胞表面标志物表达、抗体和趋化因子分泌、蛋白酶体和免疫蛋白酶体活性以及代谢功能的测定下培养长达 72 小时。此外，进行蛋白质组学分析以鉴定参与存活、免疫原性、蛋白酶体和线粒体过程的改变水平的蛋白质。与野生型脂多糖激活的 B 细胞相比，脂多糖激活的 tafazzin 敲低 B 细胞表现出明显降低的增殖、降低的分化群 86 和分化群 69 表面标志物表达、降低的免疫球蛋白 M 抗体分泌、降低的角质形成细胞衍生趋化因子和巨噬细胞炎症蛋白-2 分泌、降低的蛋白酶体和免疫蛋白酶体活性以及降低的线粒体呼吸和糖酵解。蛋白质组学分析显示，关键蛋白靶标发生了显著变化，这些蛋白靶标调节细胞存活、免疫原性、蛋白酶体加工和线粒体功能，与上述功能研究的结果一致。结果表明，心磷脂转酰酶酶 tafazzin 通过调节线粒体功能在调节小鼠 B 细胞功能和激活过程中的代谢活性方面发挥关键作用。
