Oxysterols and calcium signal transduction

Area of Science:

• Cellular Biology
• Molecular Biology
• Biochemistry

Background:

• Ionized calcium (Ca2+) acts as a crucial second messenger regulating diverse cellular functions, including muscle contraction and cell death.
• Cellular Ca2+ levels are dynamically controlled by influx through ion channels and extrusion mechanisms, generating specific spatiotemporal patterns that dictate cellular responses.
• Oxysterols, particularly oxidized low-density lipoprotein, can rapidly increase cytoplasmic Ca2+ concentrations within seconds, preceding other cellular stress responses.

Purpose of the Study:

• To review the mechanisms by which oxysterols influence calcium (Ca2+) signal transduction.
• To explore the potential roles of oxysterol-mediated Ca2+ signaling in physiological processes and pathological conditions, such as atherosclerosis.
• To highlight the knowledge gaps regarding the molecular links between oxysterol concentrations and Ca2+ signaling alterations.

Main Methods:

• Literature review of studies investigating oxysterol effects on cellular calcium.
• Analysis of research on Ca2+ channels, pumps, and buffering systems in relation to oxysterols.
• Examination of evidence linking altered Ca2+ homeostasis to oxysterol-induced cellular dysfunction.

Main Results:

• Oxysterol exposure triggers rapid increases in cytosolic Ca2+ concentration, occurring before reactive oxygen species generation or gene expression changes.
• Prolonged exposure to oxysterols modulates Ca2+ signal transduction, impacting cellular Ca2+ homeostasis.
• Altered Ca2+ homeostasis due to oxysterols may underlie pathologies like vascular smooth muscle hyporeactivity and macrophage ER stress-induced cell death in atherosclerosis.

Conclusions:

• Oxysterols significantly impact cellular Ca2+ signaling, with rapid and long-term effects.
• Dysregulation of Ca2+ homeostasis by oxysterols is implicated in the pathogenesis of atherosclerosis.
• Understanding the molecular mechanisms coupling oxysterols to Ca2+ signaling is critical for elucidating their role in health and disease.