Evaluation of YAP signaling in a rat tympanic membrane under a continuous negative pressure load and in human middle ear cholesteatoma

Abstract

Objectives: Mechanotransduction plays an important role in cell-proliferative activities. Negative pressure in the middle ear is thought to be an important factor related to the etiology of acquired middle ear cholesteatoma. However, the correlation between negative pressure in the middle ear and the mechanism of middle ear cholesteatoma formation remains unclear. In this study, we investigated the expression of key molecules for mechanotransduction immunohistochemically.

Methods: An immunohistochemical analysis was performed using anti-Wnt5a (a marker of alternative Wnt signaling), -Yes-associated protein (YAP) (a marker of mechanosensing) and -pYAP (phosphorylated YAP at Ser 127: inactivated YAP) antibody in the tympanic membrane (TM) under a negative pressure load and in human middle ear cholesteatoma tissues.

Results: The number of Wnt5a-positive cells had increased and YAP nuclear translocation was observed in epithelial and mesenchymal cells in the pars flaccida (PF) of the TM under a negative-pressure load and in human middle ear cholesteatoma tissues.

Conclusions: We demonstrated that negative pressure in the middle ear might possibly induce cell proliferation PF of TM in response to mechanical force (mechanotransduction) through YAP nuclear translocation mediated by alternative Wnt signaling, thus affecting human middle ear cholesteatoma formation.

Chinese abstract

目的：机械传导在细胞增殖活动中起重要作用。中耳负压被认为是与获得性中耳胆脂瘤病因有关的重要因素。然而, 中耳负压与中耳胆脂瘤形成机制之间的相关性尚不清楚。在本研究中, 我们从免疫组织化学的角度调查了机械转导的关键分子的表达。

方法：使用抗Wnt5a（替代Wnt信号通路的标记）、抗YAP（机械感受标记）和抗pYAP（Ser 127磷酸化YAP：灭活YAP）抗体, 进行在负压状态的TM内和中耳胆脂瘤组织中的免疫组织化学分析。

结果：在负压力负荷下和人中耳胆脂瘤组织中, Wnt5a阳性细胞数量增加, 并且在TM的PF中的上皮和间充质细胞中观察到YAP核易位。

结论：我们证实, 中耳的负压可能 由于对 通过一种替代的Wnt信号通路来传递的是相关蛋白（YAP）核易位的机械力（机械转导）的反应而诱发鼓膜松弛部（PF）中的细胞增殖, 从而影响人类中耳胆脂瘤的形成。

Keywords:

• Negative pressure
• mechanotransduction
• YAP
• alternative Wnt signaling
• cell proliferation
• middle ear cholesteatoma

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by JSPS KAKENHI Grant Numbers JP26462608 and JP16K11186.