Modulation of store-operated Ca2+ entry by cyclic-ADP-ribose.

Area of Science:

• Cellular Physiology
• Molecular Biology
• Smooth Muscle Biology

Background:

• Store-operated calcium (Ca2+) entry is vital for cellular Ca2+ homeostasis.
• Mechanisms controlling these channels remain incompletely understood.
• Human smooth muscle cells are a relevant model for studying Ca2+ regulation.

Purpose of the Study:

• To investigate the role of the CD38-cyclic-ADP-ribose (cADPR)-ryanodine-channel (RyR) signaling pathway in store-operated Ca2+ entry.
• To identify ion channels involved in Ca2+ regulation in human myometrial cells.
• To elucidate the interaction between key signaling molecules.

Main Methods:

• Utilized human myometrial cells to study Ca2+ entry.
• Employed inhibitors of RyR (ryanodine, dantrolene, ruthenium red) and cADPR system (8-Br-cADPR, nicotinamide).
• Assessed the effect of cADPR and analogs on Ca2+ transients.
• Performed co-immunoprecipitation to detect protein interactions.

Main Results:

• Human myometrial cells exhibit functional store-operated Ca2+ entry and express TRP channels (1, 3, 4, 5, 6).
• RyR inhibitors and cADPR system inhibitors significantly reduced store-operated Ca2+ entry (50-80%).
• cADPR/analogs increased Ca2+ transients, while nicotinamide inhibited them; TRP channels, RyR, and CD38 interact in vivo.

Conclusions:

• The CD38-cADPR-RyR signaling pathway is implicated in regulating store-operated Ca2+ entry.
• This pathway plays a significant role in calcium homeostasis in human smooth muscle.
• Transient receptor potential channels, RyR, and CD38 form a functional complex in vivo.