ERK regulates strain-induced migration and proliferation from different subcellular locations

Area of Science:

• Cell Biology
• Gastroenterology
• Biophysics

Background:

• Repetitive mechanical deformation, such as intestinal peristalsis, stimulates epithelial cell proliferation and migration.
• Extracellular matrix proteins like collagen and fibronectin, and the ERK signaling pathway, are crucial for these responses.
• The precise subcellular localization of ERK's function in response to mechanical strain is not fully understood.

Purpose of the Study:

• To investigate the differential roles of ERK signaling at distinct intracellular locations in response to mechanical deformation.
• To determine if ERK's nuclear versus cytosolic actions mediate proliferation and migration differently.
• To explore the potential of targeting ERK localization for therapeutic interventions in intestinal mucosal repair.

Main Methods:

• Stable transfection of Caco-2 cells with ERK decoy vectors targeted to the nucleus or cytosol.
• Assessing cell proliferation via cell counting and cell migration using circular wound closure assays.
• Applying repetitive mechanical deformation (10% strain at 10 cycles/min) to mimic physiological conditions.
• Utilizing confocal microscopy for protein localization and Western blotting to assess downstream signaling (RSK, Elk phosphorylation).

Main Results:

• Both nuclear and cytosolic ERK decoys inhibited deformation-induced proliferation on collagen.
• Deformation-induced migration on fibronectin was blocked only by the nuclear-localized ERK decoy.
• Overexpression of Sef, sequestering ERK in the cytoplasm, also blocked strain-induced proliferation and migration.
• Inhibition of RSK or Elk signaling abolished both proliferation and migration responses to strain, with RSK isoform specificity observed.

Conclusions:

• ERK translocation to the nucleus is essential for mediating strain-induced cell motility.
• ERK signaling in both the cytosol and nucleus is required for strain-induced cell proliferation.
• Selective manipulation of ERK's subcellular compartment activity presents a potential strategy for modulating intestinal mucosal responses and promoting healing.