Intracellular pH dynamics promotes zebrafish larval tail regeneration

Area of Science:

• Regenerative Biology
• Cell Physiology
• Zebrafish Models

Background:

• Intracellular pH (pHi) regulates critical cell functions like migration and proliferation.
• The role of pHi dynamics in vivo, particularly during tissue regeneration, remains underexplored.

Purpose of the Study:

• To investigate the role of intracellular pH (pHi) dynamics during zebrafish larval tail regeneration.
• To elucidate the mechanisms by which pHi changes influence cellular behaviors and tissue repair in vivo.

Main Methods:

• Generated a transgenic zebrafish line expressing a fluorescent ratiometric pHi biosensor.
• Utilized pharmacological inhibitors (NHE inhibitor) and manipulated extracellular pH to study pHi.
• Assessed cell proliferation, inflammation, myeloid cell behavior, reactive oxygen species, and GSK3 activity.
• Employed GSK3 inhibitor BIO for rescue experiments.

Main Results:

• Tail amputation induced transient pHi decrease followed by a sustained increase.
• Inhibiting Na+/H+ exchanger (NHE) activity or lowering extracellular pH attenuated the pHi increase, reduced cell proliferation, and impaired regeneration.
• NHE inhibition led to increased inflammation, altered myeloid cell behavior, decreased reactive oxygen species, and increased GSK3 activity.
• GSK3 inhibition partially rescued regeneration defects in larvae with disrupted pHi.

Conclusions:

• pHi dynamics play a critical, previously unrecognized role in coordinating tissue behaviors during zebrafish tail regeneration.
• Na+/H+ exchanger activity is essential for maintaining pHi homeostasis and enabling effective regeneration.
• GSK3 signaling is implicated in the pHi-dependent regulation of regeneration.