Max Planck Institute for Biological Intelligence, Tools for Bio-Imaging, Am Klopferspitz 18, 82152, Martinsried, Germany.
Institute de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire (IRIBHM), 808 Route de Lennik, Université Libre de Bruxelles (ULB), 1070, Brussels, Belgium.
Nat Commun. 2023 Oct 5;14(1):6220. doi: 10.1038/s41467-023-41928-w.
Calcium in interstitial fluids is central to systemic physiology and a crucial ion pool for entry into cells through numerous plasma membrane channels. Its study has been limited by the scarcity of methods that allow monitoring in tight inter-cell spaces of living tissues. Here we present high performance ultra-low affinity genetically encoded calcium biosensors named GreenT-ECs. GreenT-ECs combine large fluorescence changes upon calcium binding and binding affinities (Kds) ranging from 0.8 mM to 2.9 mM, making them tuned to calcium concentrations in extracellular organismal fluids. We validated GreenT-ECs in rodent hippocampal neurons and transgenic zebrafish in vivo, where the sensors enabled monitoring homeostatic regulation of tissue interstitial calcium. GreenT-ECs may become useful for recording very large calcium transients and for imaging calcium homeostasis in inter-cell structures in live tissues and organisms.
细胞间隙液中的钙对于全身生理学至关重要，是通过众多质膜通道进入细胞的关键离子池。由于缺乏允许在活组织的紧密细胞间隙中进行监测的方法，其研究受到限制。在这里，我们提出了名为 GreenT-ECs 的高性能超低亲和力基因编码钙生物传感器。GreenT-ECs 在结合钙时会发生较大的荧光变化，结合亲和力（Kd）范围从 0.8 mM 到 2.9 mM，使其能够调节细胞外生物体液中的钙浓度。我们在啮齿动物海马神经元和转基因斑马鱼体内对 GreenT-ECs 进行了验证，其中传感器能够监测组织细胞间隙钙的动态平衡调节。GreenT-ECs 可能会成为记录非常大的钙瞬变以及对活组织和生物体中细胞间结构的钙动态平衡进行成像的有用工具。
