Fluorescent indicators for imaging membrane potential of organelles

Klier, Pavel; Roo, Ryan; Miller, Evan W.

doi:10.1016/j.cbpa.2022.102203

Cited by 10 publications

(8 citation statements)

References 42 publications

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“…LTP-mediated lipid transfer has been observed between ER and all other organelles with different lumen potential (Figure 1a). While the ER lumen is approximately neutral relative to the cytosol, the lumen of mitochondria or lysosome has an electric potential of −200 − −100 mV or +30 − +120 mV, respectively [51]. Even a small gradient of electric potential between different organelle membranes could provide a huge driving force for lipid transfer with the help of lipid scramblases.…”

Section: Lipid Transfer Through Lipid Transfer Proteins and Scramblasesmentioning

confidence: 99%

Lipid osmosis, membrane tension, and other mechanochemical driving forces of lipid flow

Zhang,

Lin

2024

Preprint

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Nonvesicular lipid transport among different membranes or membrane domains plays crucial roles in processes such as lipid homeostasis and organelle biogenesis. However, the forces that drive such lipid transport are not well understood. We propose that lipids tend to flow towards the membrane area with a higher membrane protein density in a process termedlipid osmosis. This process lowers the membrane tension in the area when the lipid flow reaches equilibrium. We examine the thermodynamic basis and experimental evidence of lipid osmosis and the correspondingosmotic membrane tension. We predict that lipid osmosis can drive lipid flows between different membrane regions through lipid transfer proteins, scramblases, or other similar barriers that selectively pass lipids but not membrane proteins. We also speculate on the biological functions of lipid osmosis. Finally, we explore other driving forces for lipid transfer and describe potential methods and systems to further test our theory.

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Section: Lipid Transfer Through Lipid Transfer Proteins and Scramblasesmentioning

confidence: 99%

Lipid osmosis, membrane tension, and other mechanochemical driving forces of lipid flow

Zhang,

Lin

2024

Preprint

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“…Organic molecules with positively charged and hydrophobic moieties can localize in mitochondria and endoplasmic reticulum due to the negative transmembrane potential of these organelles. 23 Accordingly, we evaluated the subcellular localization property of MN_NTR using commercial trackers for mitochondria, the endoplasmic reticulum (ER), and lysosomes. The observed Pearson's correlation coefficient (PCC) values were 0.75 (mitochondria), 0.71 (ER), and 0.54 (lysosome), respectively (Figure 4a−c).…”

Section: Synthesis Of Mn_ntrmentioning

confidence: 99%

“…The higher localization of MN_NTR in mitochondria than ER can be correlated to the higher net negative membrane potential of the former (−200 to −100 mV) than the latter (−50 to −10 mV). 23 Please note that the localization of NTR probes in lysosomes is usually facilitated by the basic groups in the structure such as morpholine. 24 Imaging of NTR in an Acute Kidney Injury Model.…”

Section: Synthesis Of Mn_ntrmentioning

confidence: 99%

Nitroreductase-Triggered Fluorophore Labeling of Cells and Tissues under Hypoxia

Yang,

Jung,

Shil

et al. 2024

Anal. Chem.

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Several reductases, including nitroreductase, are upregulated under hypoxic conditions characterized by an oxygen-deficient microenvironment. Given that hypoxia is a prominent feature of solid tumors, our investigation focused on developing a bioconjugative probe designed for staining tissue under hypoxic conditions, particularly activated by nitroreductase. This probe, developed using our trigger-release-bioconjugation system rooted in the ortho-quinone methide chemistry, exhibited selective activation by nitroreductase and fluorophore labeling within mitochondria and endoplasmic reticulum. As a result, it displayed sustained fluorescence that persisted even after washing steps in cells and tissues. We applied this innovative probe to stain mouse kidney tissue in an acute kidney injury model induced by inadequate oxygen supply. Among various organ tissues examined, only kidney tissue showed significantly higher fluorescence in the injury model compared with the control tissue, as revealed by two-photon microscopic imaging. This research presents a promising avenue for the development of practical staining agents for image-guided tumor surgery.

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“…GEVIs are based on an integral membrane protein and provide numerous advantages, including the ability to target the sensor to specific cell types by selecting cell-specific promoters or by enabling multicolor images [ 22 ]. They are constructed using either a single fluorophore or a pair of fluorescence resonance energy transfer (FRET) fluorochromes [ 22 , 23 , 24 , 25 ]. In such (FRET) sensors, two different-colored fluorochromes, donor and acceptor, are fused in tandem to a voltage-sensitive transmembrane protein, such as the voltage-sensing domain of the Ciona intestinalis voltage-sensing phosphatase (Ci-VSP) [ 26 ].…”

Section: Introductionmentioning

confidence: 99%

Use of FRET-Sensor ‘Mermaid’ to Detect Subtle Changes in Membrane Potential of Primary Mouse PASMCs

Dartsch,

Kraut,

Mayer

et al. 2024

Cells

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Subtle changes in the membrane potential of pulmonary arterial smooth muscle cells (PASMCs) are pivotal for controlling pulmonary vascular tone, e.g., for initiating Hypoxic Pulmonary Vasoconstriction, a vital mechanism of the pulmonary circulation. In our study, we evaluated the ability of the fluorescence resonance energy transfer (FRET)-based voltage-sensor Mermaid to detect such subtle changes in membrane potential. Mouse PASMCs were isolated and transduced with Mermaid-encoding lentiviral vectors before the acceptor/donor emission ratio was assessed via live cell FRET-imaging. Mermaid’s sensitivity was tested by applying specific potassium chloride (KCl) concentrations. These KCl concentrations were previously validated by patch clamp recordings to induce depolarization with predefined amplitudes that physiologically occur in PASMCs. Mermaid’s emission ratio dose-dependently increased upon depolarization with KCl. However, Mermaid formed unspecific intracellular aggregates, which limited the usefulness of this voltage sensor. When analyzing the membrane rim only to circumvent these unspecific signals, Mermaid was not suitable to resolve subtle changes in the membrane potential of ≤10 mV. In summary, we found Mermaid to be a suitable alternative for reliably detecting qualitative membrane voltage changes of more than 10 mV in primary mouse PASMCs. However, one should be aware of the limitations associated with this voltage sensor.

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Fluorescent indicators for imaging membrane potential of organelles

Cited by 10 publications

References 42 publications

Lipid osmosis, membrane tension, and other mechanochemical driving forces of lipid flow

Lipid osmosis, membrane tension, and other mechanochemical driving forces of lipid flow

Nitroreductase-Triggered Fluorophore Labeling of Cells and Tissues under Hypoxia

Use of FRET-Sensor ‘Mermaid’ to Detect Subtle Changes in Membrane Potential of Primary Mouse PASMCs

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