Departments of Cell Biology and of Biochemistry, University of Texas Southwestern Medical, Dallas, TX, United States.
Touchstone Diabetes Center, University of Texas Southwestern Medical Center, Dallas, TX, United States.
Front Endocrinol (Lausanne). 2021 Mar 9;12:613964. doi: 10.3389/fendo.2021.613964. eCollection 2021.
Appropriate insulin secretion is essential for maintaining euglycemia, and impairment or loss of insulin release represents a causal event leading to diabetes. There have been extensive efforts of studying insulin secretion and its regulation using a variety of biological preparations, yet it remains challenging to monitor the dynamics of insulin secretion at the cellular level in the intact pancreas of living animals, where islet cells are supplied with physiological blood circulation and oxygenation, nerve innervation, and tissue support of surrounding exocrine cells. Herein we presented our pilot efforts of ZIMIR imaging in pancreatic islet cells in a living mouse. The imaging tracked insulin/Zn release of individual islet β-cells in the intact pancreas with high spatiotemporal resolution, revealing a rhythmic secretion activity that appeared to be synchronized among islet β-cells. To facilitate probe delivery to islet cells, we also developed a chemogenetic approach by expressing the HaloTag protein on the cell surface. Finally, we demonstrated the application of a fluorescent granule zinc indicator, ZIGIR, as a selective and efficient islet cell marker in living animals through systemic delivery. We expect future optimization and integration of these approaches would enable longitudinal tracking of beta cell mass and function by optical imaging.
适当的胰岛素分泌对于维持血糖正常至关重要，而胰岛素释放的损害或丧失则代表了导致糖尿病的一个因果事件。人们已经投入了大量的精力来研究使用各种生物制剂的胰岛素分泌及其调节，但在完整的活体动物胰腺中，胰岛细胞供应着生理的血液循环和氧合、神经支配以及周围外分泌细胞的组织支持，要监测细胞水平的胰岛素分泌动力学仍然具有挑战性。在这里，我们展示了我们在活体小鼠胰岛细胞中进行 ZIMIR 成像的初步尝试。该成像以高时空分辨率跟踪完整胰腺中单个胰岛 β 细胞的胰岛素/Zn 释放，揭示了一种似乎在胰岛 β 细胞之间同步的有节奏分泌活动。为了促进探针向胰岛细胞的传递，我们还通过在细胞表面表达 HaloTag 蛋白开发了一种化学遗传方法。最后，我们通过系统给药证明了荧光颗粒锌指示剂 ZIGIR 作为一种选择性和有效的活体动物胰岛细胞标记物的应用。我们期望这些方法的未来优化和整合将能够通过光学成像对β细胞质量和功能进行纵向跟踪。
