Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720.
Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720.
J Neurosci. 2024 Jul 24;44(30):e1717232024. doi: 10.1523/JNEUROSCI.1717-23.2024.
Magnetogenetics was developed to remotely control genetically targeted neurons. A variant of magnetogenetics uses magnetic fields to activate transient receptor potential vanilloid (TRPV) channels when coupled with ferritin. Stimulation with static or RF magnetic fields of neurons expressing these channels induces Ca transients and modulates behavior. However, the validity of ferritin-based magnetogenetics has been questioned due to controversies surrounding the underlying mechanisms and deficits in reproducibility. Here, we validated the magnetogenetic approach Ferritin-iron Redistribution to Ion Channels (FeRIC) using electrophysiological (Ephys) and imaging techniques. Previously, interference from RF stimulation rendered patch-clamp recordings inaccessible for magnetogenetics. We solved this limitation for FeRIC, and we studied the bioelectrical properties of neurons expressing TRPV4 (nonselective cation channel) and transmembrane member 16A (TMEM16A; chloride-permeable channel) coupled to ferritin (FeRIC channels) under RF stimulation. We used cultured neurons obtained from the rat hippocampus of either sex. We show that RF decreases the membrane resistance (Rm) and depolarizes the membrane potential in neurons expressing TRPV4 RF does not directly trigger action potential firing but increases the neuronal basal spiking frequency. In neurons expressing TMEM16A, RF decreases the Rm, hyperpolarizes the membrane potential, and decreases the spiking frequency. Additionally, we corroborated the previously described biochemical mechanism responsible for RF-induced activation of ferritin-coupled ion channels. We solved an enduring problem for ferritin-based magnetogenetics, obtaining direct Ephys evidence of RF-induced activation of ferritin-coupled ion channels. We found that RF does not yield instantaneous changes in neuronal membrane potentials. Instead, RF produces responses that are long-lasting and moderate, but effective in controlling the bioelectrical properties of neurons.
磁遗传学旨在远程控制基因靶向神经元。磁遗传学的一种变体使用磁场在与铁蛋白结合时激活瞬时受体电位香草酸 (TRPV) 通道。表达这些通道的神经元的静磁场或射频磁场刺激会引起钙瞬变并调节行为。然而，由于围绕潜在机制的争议以及再现性缺陷，铁蛋白基磁遗传学的有效性受到了质疑。在这里，我们使用电生理学 (Ephys) 和成像技术验证了磁遗传学方法 Ferritin-iron Redistribution to Ion Channels (FeRIC)。以前，射频刺激会干扰膜片钳记录，使磁遗传学无法进行。我们解决了 FeRIC 的这个限制，并研究了与铁蛋白 (FeRIC 通道) 偶联的表达 TRPV4（非选择性阳离子通道）和跨膜成员 16A（TMEM16A；氯离子通透通道）的神经元的生物电特性在射频刺激下。我们使用来自大鼠海马体的两性培养神经元。我们表明，射频降低了表达 TRPV4 的神经元的膜电阻 (Rm) 并使膜电位去极化 射频不会直接触发动作电位放电，但会增加神经元的基础放电频率。在表达 TMEM16A 的神经元中，射频降低 Rm、超极化膜电位并降低放电频率。此外，我们证实了先前描述的负责铁蛋白偶联离子通道射频诱导激活的生化机制。我们解决了铁蛋白基磁遗传学中一个长期存在的问题，获得了射频诱导铁蛋白偶联离子通道激活的直接 Ephys 证据。我们发现射频不会导致神经元膜电位的瞬时变化。相反，射频产生持久且适度的反应，但可有效控制神经元的生物电特性。
