Ca2+ ionophores trigger membrane remodeling without a need for store-operated Ca2+ entry

Area of Science:

• Cell Biology
• Biochemistry
• Membrane Biophysics

Background:

• Calcium ionophores are potent agents for rapid in vitro membrane remodeling.
• This remodeling exposes aminophospholipids on blood cells, creating a catalytic surface for coagulation.
• The role of cytosolic calcium increase via store-operated calcium entry (SOCE) in ionophore-induced membrane remodeling is unclear.

Purpose of the Study:

• To investigate whether store-operated calcium entry (SOCE) is essential for ionophore-induced rapid membrane remodeling.
• To determine if ionophores trigger membrane remodeling independently of SOCE.

Main Methods:

• Utilized two mutant B lymphoblast cell lines with defective SOCE or altered membrane remodeling.
• Simultaneously assessed cytosolic calcium ion increase ([Ca2+]i) and membrane remodeling.
• Compared the effects of calcium ionophores and the Ca2+-ATPase inhibitor thapsigargin.

Main Results:

• Ionophores effectively induced rapid membrane remodeling in the studied cell lines.
• The presence of a functional SOCE pathway was not required for ionophore-mediated membrane remodeling.
• Thapsigargin elevated [Ca2+]i via SOCE but did not induce the same rapid membrane remodeling.

Conclusions:

• Ionophore-induced membrane remodeling occurs independently of store-operated calcium entry (SOCE).
• The findings differentiate the mechanisms of calcium ionophores and thapsigargin in cellular responses.
• This suggests distinct pathways mediate calcium influx and subsequent membrane changes.