Departamento de Morfología y Biología Celular, Grupo SINPOS, Universidad de Oviedo, Oviedo, Spain.
Departamento de Morfología y Biología Celular, Grupo SINPOS, Universidad de Oviedo, Oviedo, Spain; Servicio de Anatomía Patológica, Complejo Hospitalario Universitario de Salamanca, Salamanca, Spain.
Ann Anat. 2022 Aug;243:151953. doi: 10.1016/j.aanat.2022.151953. Epub 2022 May 4.
PIEZO2 is a transmembrane protein forming part of an ion channel required for mechanotransduction. In humans, PIEZO2 is present in axon terminals of adult Meissner and Pacinian corpuscles, as well as Merkel cells in Merkel cell-neurite complexes.
To study the acquisition of functional capability for mechanotransduction of developing type I slowly adapting low-threshold mechanoreceptors, i.e., Merkel cell-neurite complexes, a battery of immunohistochemical and immunofluorescence techniques was performed on human skin specimens covering the whole development and growth, from 11 weeks of estimated gestational age to 20 years of life. In addition, developmental expression of PIEZO2 type I (Meissner's corpuscles) and type II (Pacinian corpuscles) rapidly adapting mechanoreceptors was studied in parallel.
The first evidence of Merkel cells showing the typical morphology and placement was at 13 weeks of estimated gestation age, and at this time positive immunoreactivity for PIEZO2 was achieved. PIEZO2 expression in axons terminals started at 23 WEGA in Pacinian corpuscles and at 36 WEGA in the case of Meissner corpuscles. The occurrence of PIEZO2 in Merkel cells, Meissner and Pacinian corpuscles was maintained for all the time investigated. Interestingly PIEZO2 was absent in most Aβ type I slowly adapting low-threshold mechanoreceptors that innervate MC while it was regularly present in most Aβ type I and type II rapidly adapting low-threshold mechanoreceptors that supplies Meissner and Pacinian corpuscles.
The present results provide evidence that human cutaneous mechanoreceptors could perform mechanotransduction already during embryonic development.
PIEZO2 是一种跨膜蛋白，构成机械转导所需的离子通道的一部分。在人类中，PIEZO2 存在于成年 Meissner 和 Pacinian 小体的轴突末梢以及 Merkel 细胞-Merkel 细胞神经末梢复合物中。
为了研究发育中的 I 型慢适应低阈值机械感受器（即 Merkel 细胞-神经末梢复合物）获得机械转导功能的能力，我们对涵盖整个发育和生长过程的人类皮肤标本进行了一系列免疫组织化学和免疫荧光技术研究，从估计的妊娠 11 周龄到 20 岁。此外，还平行研究了 PIEZO2 型 I（Meissner 小体）和 II 型（Pacinian 小体）快速适应机械感受器的发育表达。
具有典型形态和位置的 Merkel 细胞的最早证据出现在估计的妊娠 13 周龄，此时已获得 PIEZO2 的阳性免疫反应性。Pacinian 小体中的轴突末端的 PIEZO2 表达始于 23 周龄，Meissner 小体中的 PIEZO2 表达始于 36 周龄。在整个研究期间，Merkel 细胞、Meissner 和 Pacinian 小体中都存在 PIEZO2。有趣的是，PIEZO2 在支配 Merkel 细胞的大多数 Aβ 型 I 慢适应低阈值机械感受器中缺失，而在供应 Meissner 和 Pacinian 小体的大多数 Aβ 型 I 和 II 快速适应低阈值机械感受器中则经常存在。
本研究结果提供了证据表明，人类皮肤机械感受器在胚胎发育过程中即可进行机械转导。
