Department of Otorhinolaryngology-Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai.
Eur J Histochem. 2019 Jun 5;63(2):3025. doi: 10.4081/ejh.2019.3025.
The Kölliker's organ is a transient epithelial structure during cochlea development that gradually degenerates and disappears at postnatal 12-14 days (P12-14). While apoptosis has been shown to play an essential role in the degeneration of the Kölliker's organ, the role of another programmed cell death, autophagy, remains unclear. In our study, autophagy markers including microtubule associated protein light chain 3-II (LC3-II), sequestosome 1 (SQSTM1/p62) and Beclin1 were detected in the supporting cells of the Kölliker's organ through immunohistochemistry staining. In addition, Western blot and real-time PCR revealed a gradually decreased expression of LC3-II and an increased expression of p62 during early postnatal development. Compared to apoptosis markers that peaks between P7 and P10, autophagy flux peaked earlier at P1 and decreased from P1 to P14. By transmission electron microscopy, we observed representative autophagosome and autolysosome that packaged various organelles in the supporting cells of the Kölliker's organ. During the degeneration, these organelles were digested via autophagy well ahead of the cellular apoptosis. These results suggest that autophagy plays an important role in transition and degeneration of the Kölliker's organ prior to apoptosis during the early postnatal development.
科尔利克氏器是耳蜗发育过程中的一种短暂的上皮结构，它会在出生后 12-14 天（P12-14）逐渐退化和消失。虽然已经表明细胞凋亡在科尔利克氏器的退化中起着至关重要的作用，但另一种程序性细胞死亡——自噬的作用仍不清楚。在我们的研究中，通过免疫组织化学染色，在科尔利克氏器的支持细胞中检测到自噬标志物，包括微管相关蛋白轻链 3-II（LC3-II）、自噬体相关蛋白 1（SQSTM1/p62）和 Beclin1。此外，Western blot 和实时 PCR 显示 LC3-II 的表达逐渐减少，p62 的表达在出生后早期逐渐增加。与凋亡标志物在 P7 至 P10 之间达到峰值相比，自噬通量在 P1 时达到峰值，并从 P1 下降到 P14。通过透射电子显微镜，我们观察到科尔利克氏器支持细胞中存在代表性的自噬体和自溶酶体，它们包裹着各种细胞器。在退化过程中，这些细胞器通过自噬被提前降解，而细胞凋亡则发生在其后。这些结果表明，自噬在出生后早期的细胞凋亡之前，在科尔利克氏器的过渡和退化中发挥着重要作用。
