Studying Proton Gradients Across the Nuclear Envelope.

Area of Science:

• Cell Biology
• Biophysics
• Biochemistry

Background:

• Nuclear pore complexes suggest free ion movement, implying similar pH regulation between cytosol and nucleus.
• Previous nuclear pH studies yielded conflicting results, ranging from cytosol-like to more alkaline.
• Existing methods lack the rigor for accurate nuclear pH measurement, particularly in situ titrations.

Purpose of the Study:

• To develop and validate a robust method for accurate in situ pH measurement within the nucleus and cytosol.
• To address the limitations of previous studies in nuclear pH determination.
• To enable precise pH quantification in distinct cellular compartments.

Main Methods:

• Utilized SNARF-1, a pH-sensitive fluorescent probe, for simultaneous labeling of both nucleus and cytosol.
• Employed ratio imaging microscopy to analyze fluorescence intensity ratios.
• Performed steady-state pH measurements followed by in situ titrations for calibration within each compartment.

Main Results:

• Successfully demonstrated a method for accurate pH measurement in both nuclear and cytosolic compartments.
• Showcased the utility of SNARF-1 fluorescence and ratio imaging for intracellular pH analysis.
• Provided a corrected approach for assigning pH values in distinct cellular domains.

Conclusions:

• The developed method overcomes previous limitations in nuclear pH measurement.
• Accurate in situ titration is crucial for reliable pH determination in different cellular compartments.
• This technique offers a more rigorous approach to understanding intracellular pH regulation.