STIM1 phosphorylation triggered by epidermal growth factor mediates cell migration.

Area of Science:

• Cell Biology
• Molecular Signaling
• Calcium Homeostasis

Background:

• Stromal Interaction Molecule 1 (STIM1) regulates store-operated calcium entry (SOCE), a critical process for calcium-dependent cellular functions.
• Phosphorylation of STIM1 by ERK1/2 has been observed but its physiological role remains unclear.

Purpose of the Study:

• To investigate the role of STIM1 phosphorylation in epidermal growth factor (EGF)-induced cell signaling and function.
• To elucidate the specific STIM1 phosphorylation sites and their impact on cellular events.

Main Methods:

• Utilized Ishikawa cells, a human endometrial adenocarcinoma cell line.
• Stimulated cells with EGF or H-Ras(G12V) and analyzed STIM1 phosphorylation using ERK1/2 inhibitors (PD0325901) and calcium channel blockers (SKF96365).
• Employed site-directed mutagenesis (Ser-to-Ala and phosphomimetic mutations) to assess the functional significance of STIM1 phosphorylation, including effects on cell migration and epithelial-mesenchymal transition (EMT) markers.

Main Results:

• EGF and H-Ras(G12V) induced STIM1 phosphorylation at Ser575, Ser608, and Ser621, sensitive to ERK1/2 inhibition, occurring independently of extracellular calcium.
• EGF triggered STIM1 dissociation from EB1, a microtubule-associated protein.
• Impaired STIM1 phosphorylation reduced Ishikawa cell migration and altered vimentin and E-cadherin expression, indicative of EMT.
• Phosphomimetic STIM1 mutations restored cell migration and normalized EMT marker profiles.

Conclusions:

• STIM1 phosphorylation at specific ERK1/2 sites is a key event in EGF-mediated signaling, preceding calcium entry.
• This phosphorylation is essential for regulating cell migration and epithelial-mesenchymal transition processes.
• STIM1 phosphorylation represents a novel regulatory mechanism in EGF-driven cellular responses.