Abstract

Current neuromodulation techniques such as optogenetics and deep-brain stimulation are transforming basic and translational neuroscience. These two neuromodulation approaches are, however, invasive since surgical implantation of an optical fiber or wire electrode is required. Here, we have invented a non-invasive magnetogenetics that combines the genetic targeting of a magnetoreceptor with remote magnetic stimulation. The non-invasive activation of neurons was achieved by neuronal expression of an exogenous magnetoreceptor, an iron-sulfur cluster assembly protein 1 (Isca1). In HEK-293 cells and cultured hippocampal neurons expressing this magnetoreceptor, application of an external magnetic field resulted in membrane depolarization and calcium influx in a reproducible and reversible manner, as indicated by the ultrasensitive fluorescent calcium indicator GCaMP6s. Moreover, the magnetogenetic control of neuronal activity might be dependent on the direction of the magnetic field and exhibits on-response and off-response patterns for the external magnetic field applied. The activation of this magnetoreceptor can depolarize neurons and elicit trains of action potentials, which can be triggered repetitively with a remote magnetic field in whole-cell patch-clamp recording. In transgenic Caenorhabditis elegans expressing this magnetoreceptor in myo-3-specific muscle cells or mec-4-specific neurons, application of the external magnetic field triggered muscle contraction and withdrawal behavior of the worms, indicative of magnet-dependent activation of muscle cells and touch receptor neurons, respectively. The advantages of magnetogenetics over optogenetics are its exclusive non-invasive, deep penetration, long-term continuous dosing, unlimited accessibility, spatial uniformity and relative safety. Like optogenetics that has gone through decade-long improvements, magnetogenetics, with continuous modification and maturation, will reshape the current landscape of neuromodulation toolboxes and will have a broad range of applications to basic and translational neuroscience as well as other biological sciences. We envision a new age of magnetogenetics is coming.

Keywords

Abstract

現(xiàn)有的神經(jīng)調(diào)控技術(shù), 如光遺傳學(xué)和深部腦刺激, 正在改變基礎(chǔ)研究和臨床轉(zhuǎn)化神經(jīng)科學(xué)。然而這兩種調(diào)控方式都是損傷性的, 因?yàn)樾枰诖竽X里植入光纖或者金屬電極。在這個(gè)研究中, 我們新發(fā)明了一種非損傷性的神經(jīng)調(diào)控方法, 稱之為“磁遺傳學(xué)”。這個(gè)方法結(jié)合基因打靶和磁場(chǎng)刺激, 將這個(gè)進(jìn)化上高度保守的外源性的磁感應(yīng)受體, 一種鐵硫蛋白 (Isca1), 導(dǎo)入到大腦特定的區(qū)域, 使其在特定的神經(jīng)元中表達(dá), 然后通過外部磁場(chǎng)刺激, 激活大腦特定的區(qū)域。在體外培養(yǎng)的HEK-293細(xì)胞和海馬神經(jīng)元中表達(dá)該磁感應(yīng)受體, 施加外部磁場(chǎng), 能激活細(xì)胞, 導(dǎo)致細(xì)胞膜去極化和鈣離子內(nèi)流。這種鈣離子內(nèi)流可以由超靈敏熒光鈣指示劑GCaMP6s檢測(cè)出來(lái), 當(dāng)細(xì)胞內(nèi)鈣離子濃度升高時(shí), GCaMP6s的熒光強(qiáng)度會(huì)升高。此外, 磁場(chǎng)控制神經(jīng)元的活動(dòng)可能依賴于磁場(chǎng)的方向以及磁場(chǎng)的打開和關(guān)閉, 對(duì)于不同方向的磁場(chǎng)刺激, 以及磁場(chǎng)的開關(guān), 神經(jīng)元有不同的反應(yīng)模式。全細(xì)胞膜片鉗記錄的神經(jīng)元的電信號(hào)顯示外界磁場(chǎng)可以使表達(dá)磁感應(yīng)受體的神經(jīng)元去極化, 從而引起動(dòng)作電位。通過肌肉細(xì)胞特定的啟動(dòng)子myo-3將這個(gè)受體導(dǎo)入線蟲的肌肉細(xì)胞內(nèi), 外加磁場(chǎng)可以觸發(fā)線蟲肌肉收縮 ; 通過神經(jīng)細(xì)胞的特定啟動(dòng)子mec-4將磁感應(yīng)受體導(dǎo)入應(yīng)力感受神經(jīng)元, 外界磁場(chǎng)的刺激可誘發(fā)線蟲后退的行為。磁遺傳學(xué)和光遺傳學(xué)相比, 明顯的優(yōu)勢(shì)是非損傷性, 高穿透深度, 長(zhǎng)久持續(xù)刺激, 無(wú)空間限制性, 空間均勻性和相對(duì)安全性。正如光遺傳學(xué)通過了十年之久的改之后所取得的進(jìn)展一樣, 磁遺傳學(xué)開辟了一個(gè)全新的神經(jīng)調(diào)控領(lǐng)域, 經(jīng)過持續(xù)的發(fā)展和成熟, 將有廣泛的應(yīng)用前景, 并將極大地推動(dòng)基礎(chǔ)研究, 轉(zhuǎn)化神經(jīng)科學(xué)以及其它生物科學(xué)的發(fā)展。我們預(yù)見一個(gè)磁遺傳學(xué)時(shí)代的來(lái)臨。

Xiaoyang Long and Jing Ye contributed equally to this work.

The online version of this article (doi:10.1007/s11434-015-0902-0) contains supplementary material, which is available to authorized users.