Mitochondria-Anchored Molecular Thermometer Quantitatively Monitoring Cellular Inflammations

Abstract

Temperature in mitochondria can be a critical indicator of cell metabolism. Given the highly dynamic and inhomogeneous nature of mitochondria, it remains a big challenge to quantitatively monitor the local temperature changes during different cellular processes. To implement this task, we extend our strategy on mitochondria-anchored thermometers from “on–off” probe Mito-TEM to a ratiometric probe Mito-TEM 2.0 based on the Förster resonance energy transfer mechanism. Mito-TEM 2.0 exhibits not only a sensitive response to temperature through the ratiometric changes of dual emissions but also the specific immobilization in mitochondria via covalent bonds. Both characters support accurate and reliable detection of local temperature for a long time, even in malfunctioning mitochondria. By applying Mito-TEM 2.0 in fluorescence ratiometric imaging of cells and zebrafishes, we make a breakthrough in the quantitative visualization of mitochondrial temperature rises in different inflammation states.

Accurate and Real‐Time Detection Method for the Exothermic Behavior of Enzymatic Nano‐Microregions Using Temperature‐Sensitive Amino‐AgInS2 Quantum Dots

“…The abovementioned results demonstrate that a large temperature difference exists in the local nano‐microregion of the lipase, which is consistent with the results reported in other studies (e.g., temperature change in mitochondria [ 19,20 ] ). The dispute about the data of temperature change in nano‐microregion indicates that the understanding of the phenomenon is different.…”

“…measured a 3 °C increase in mitochondrial temperature in MCF‐7 cells upon PMA stimulation. [ 19 ] By contrast, D. Chretien et al. used MitoThermo Yellow, a temperature organic dye, as nanothermometers targeting the mitochondria and demonstrated that mitochondrial temperature in human embryonic kidney 293 cells increased by more than 10 °C at a constant external temperature of 38 °C when the respiratory chain was fully functional.…”

Multichannel Fluorescence Microscopy: Advantages of Going beyond a Single Emission

“…To overcome this limitation, other thermally sensitive energy transfer processes have been investigated to achieve better thermal resolutions with RE ions. [139,140] In addition, alternative materials have been engineered to present multiple emission bands, on their own or in synergy, for ratiometric thermometry, such as fluorescent proteins, [141] organic dyes, [142,143] nanopolymers, [144] quantum dots, [145,146] or gold nanoparticles. [147] A recent example of ratiometric thermometry makes use of the spectral shift produced in the emission of GFP.…”

Opto-thermal technologies for microscopic analysis of cellular temperature-sensing systems

“…Finally, there remains substantial room for the development of advanced optical heaters and thermometers. Intracellular thermometry reported 1 °C or greater local temperature gradients in both stimulated and non-stimulated cells at the organelle level, such as in nuclei (Okabe et al 2012;Nakano et al 2017) (see also Vu et al 2021 for the controversial result), mitochondria (Okabe et al 2012;Kiyonaka et al 2013;Homma et al 2015;Nakano et al 2017;Huang et al 2018Huang et al , 2021Chrétien et al 2018Chrétien et al , 2020Savchuk et al 2019;Di et al 2021), and ER/SR (Kiyonaka et al 2013;Arai et al 2014;Itoh et al 2016;Hou et al 2017;Kriszt et al 2017;Oyama et al 2020). However, these experimental results largely contradict to the estimates based on the theories of macroscopic heat transfer, which expect the local temperature rises of the orders of 10 −4 to 10 −5 °C.…”