Atopy (Allergy) Research Center, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan.
J Allergy Clin Immunol. 2011 May;127(5):1267-76.e6. doi: 10.1016/j.jaci.2010.12.1078. Epub 2011 Feb 18.
Autophagy plays a crucial role in controlling various biological responses including starvation, homeostatic turnover of long-lived proteins, and invasion of bacteria. However, a role for autophagy in development and/or function of mast cells is unknown.
To investigate a role for autophagy in mast cells, we generated bone marrow-derived mast cells (BMMCs) from mice lacking autophagy related gene (Atg) 7, an essential enzyme for autophagy induction.
Bone marrow-derived mast cells were generated from bone marrow cells of control and IFN-inducible Atg7-deficient mice, and morphologic and functional analyses were performed.
We found that conversion of type I to type II light chain (LC3)-II, a hallmark of autophagy, was constitutively induced in mast cells under full nutrient conditions, and LC3-II localized in secretory granules of mast cells. Although deletion of Atg7 did not impair the development of BMMCs, Atg7(-/-) BMMCs showed severe impairment of degranulation, but not cytokine production on FcεRI cross-linking. Intriguingly, LC3-II but not LC3-I was co-localized with CD63, a secretory lysosomal marker, and was released extracellularly along with degranulation in Atg7(+/+) but not Atg7(-/-) BMMCs. Moreover, passive cutaneous anaphylaxis reactions were severely impaired in mast cell-deficient WBB6F1-W/W(V) mice reconstituted with Atg7(-/-) BMMCs compared with Atg7(+/+) BMMCs.
These results suggest that autophagy is not essential for the development but plays a crucial role in degranulation of mast cells. Thus, autophagy might be a potential target to treat allergic diseases in which mast cells are critically involved.
自噬在控制各种生物反应中起着至关重要的作用，包括饥饿、长寿命蛋白质的稳态周转和细菌入侵。然而，自噬在肥大细胞的发育和/或功能中的作用尚不清楚。
为了研究自噬在肥大细胞中的作用，我们从缺乏自噬相关基因（Atg）7的小鼠中生成骨髓来源的肥大细胞（BMMC），Atg7 是自噬诱导的必需酶。
从对照和 IFN 诱导型 Atg7 缺陷小鼠的骨髓细胞中生成骨髓来源的肥大细胞，并进行形态和功能分析。
我们发现，在完全营养条件下，肥大细胞中 I 型到 II 型轻链（LC3）-II 的转化，即自噬的标志，持续被诱导，LC3-II 定位于肥大细胞的分泌颗粒中。尽管 Atg7 的缺失并不影响 BMMC 的发育，但 Atg7(-/-) BMMC 在 FcεRI 交联时严重损害脱颗粒，但不损害细胞因子产生。有趣的是，LC3-II 而不是 LC3-I 与 CD63（一种分泌溶酶体标记物）共定位，并在 Atg7(+/+) BMMC 中与脱颗粒一起被释放到细胞外，但在 Atg7(-/-) BMMC 中则不然。此外，与用 Atg7(+/+) BMMC 重建的 WBB6F1-W/W(V) 肥大细胞缺陷小鼠相比，Atg7(-/-) BMMC 重建的小鼠被动皮肤过敏反应严重受损。
这些结果表明，自噬对于肥大细胞的发育不是必需的，但对于脱颗粒至关重要。因此，自噬可能是治疗肥大细胞严重参与的过敏疾病的潜在靶点。
