Agonist-Triggered Ca2+ Release From Functionally Connected Endoplasmic Reticulum and Lysosomal Ca2+ Stores in bEND.3...

Area of Science:

• Cell Biology
• Molecular Biology
• Physiology

Background:

• Endoplasmic reticulum (ER) and lysosomes are key intracellular calcium (Ca2+) stores.
• These organelles are physically and functionally interconnected.
• Understanding their communication is crucial for cellular signaling.

Purpose of the Study:

• To investigate agonist-triggered Ca2+ release from ER and lysosomes in mouse microvascular endothelial bEND.3 cells.
• To determine the functional relationship between ER and lysosomal Ca2+ stores.
• To elucidate the cross-talk mechanisms regulating Ca2+ dynamics.

Main Methods:

• Utilized Ca2+ imaging techniques in bEND.3 cells.
• Employed specific inhibitors: nigericin for lysosomes, cyclopiazonic acid (CPA) for ER.
• Investigated the effects of ATP, Ned-19, and xestospongin C on Ca2+ release.

Main Results:

• Lysosomal Ca2+ depletion by nigericin did not affect ER Ca2+ release by CPA, and vice versa.
• ATP-induced Ca2+ release involved both ER and lysosomes, partially inhibited by Ned-19 and xestospongin C.
• Depleting either ER or lysosomes abolished subsequent ATP-triggered Ca2+ release, indicating cross-talk.

Conclusions:

• ER and lysosomes function as distinct yet communicating Ca2+ stores.
• The filling state of one organelle influences the agonist-stimulated Ca2+ release of the other.
• This cross-talk mechanism is vital for regulating cellular Ca2+ signaling.