Identification and functional characterization of Piezo2-multiprotein complexes involved in mechanotransduction

我们的感官世界是丰富的。从母亲的温柔抚摸到踩到钉子的痛苦感受，我们感知和编码这些不同输入的能力对生存至关重要。然而，机械感觉，即感知机械刺激的能力，仍然是脊椎动物中最不为人所知的感觉。在脊椎动物体感系统的水平上，我们的触觉和对疼痛的感知依赖于激活专门的机械敏感神经元，这些神经元支配着皮肤和内脏。这些神经元能够检测到机械刺激是由于不同的机械敏感蛋白的表达，其中包括机械激活的离子通道。机械刺激介导离子通道门控，导致离子通量穿过膜，从而代表机械刺激转化为电编码的第一步。尽管进行了大量的研究，但这些机械门控离子通道在脊椎动物体感觉系统中的分子特性在很大程度上是未知的。在少数几个考虑的候选者中，最近发现的Piezo1和Piezo2通道代表了一种新的真正的机械敏感离子通道。在小鼠中，Piezo2在体感觉神经元中大量表达，介导快速适应的机械电流。因此，在体内敲除Piezo2会影响小鼠的触摸反应。Piezo2激活的后果可能主要取决于调节Piezo2活性的相关蛋白，这些蛋白表达的神经元类型以及它们所在的亚细胞微域。所有这些方面目前都是未知的。我们拟鉴定和研究小鼠感觉神经元中参与机械感觉的Piezo2相关蛋白复合物。为此，我们将结合定量质谱技术、小鼠行为疼痛范式、电生理学和体内蛋白质表达水平的操纵。我们期望在体感神经元中识别出机械敏感装置的新分子成分，从而有助于我们对脊椎动物体感机械感觉的理解。

Our sensory universe is rich. From a gentle touch of a mother to the painful perception of stepping on a nail, our ability to perceive and encode such different inputs is critical for survival. However, mechanosensation, the ability to perceive mechanical stimuli, remains the least understood sense in vertebrates. At the level of the vertebrate somatosensory system our sense of touch and the detection of pain rely on the activation of specialized mechanosensitive neurons which innervate the skin and internal organs. These neurons are able to detect mechanical stimuli due to the expression of distinct mechanosensitive proteins, among them mechanically activated ion channels. Mechanical stimulation mediates ion channel gating which results in ion flux across membranes, thus representing the first step in the conversion of mechanical stimuli into an electrical code. Despite intensive research efforts the molecular identity of these mechanically gated ion channels in the vertebrate somatosensory system is largely unknown. Among the few considered candidates, the very recently discovered Piezo1 and Piezo2 channels represent a novel bona fide class of mechanosensitive ion channels. In mice Piezo2 is abundantly expressed in somatosensory neurons where it mediates rapidly adapting mechanocurrents. Accordingly, in vivo knock down of Piezo2 affects touch responses in mice. The consequences of Piezo2 activation are likely to depend critically on associated proteins that regulate Piezo2 activity, on the type of neuron where these proteins are expressed and also on the subcellular microdomains where they are located. All these aspects are currently unknown. We propose to identify and study Piezo2 associated protein complexes involved in mechanosensation in sensory neurons of mice. To this end, we will combine quantitative mass spectrometry techniques, mouse behavioral pain paradigms, electrophysiology and in vivo manipulation of protein expression levels. We expect to identify novel molecular components of the mechanosensitive apparatus in somatosensory neurons and thereby contribute to our understanding of somatosensory mechanosensation in vertebrates.