A ratiometric ER calcium sensor for quantitative comparisons across cell types and subcellular regions

Area of Science:

• Cellular biology
• Neuroscience
• Biochemistry

Background:

• The endoplasmic reticulum (ER) regulates cellular calcium (Ca2+) homeostasis, crucial for numerous cellular functions.
• Dysregulation of ER Ca2+ homeostasis is implicated in various pathologies.
• Accurate quantification of ER Ca2+ levels is essential for understanding cellular physiology under different conditions.

Approach:

• Developed a ratiometric version of the ER-GCaMP probe for enhanced quantitative measurements of ER Ca2+.
• The new probe facilitates easier comparisons of Ca2+ concentrations across diverse cell types and subcellular compartments.
• Utilized the probe to measure and compare ER Ca2+ levels in primary dissociated neurons and embryonic fibroblasts.

Key Points:

• The ratiometric ER-GCaMP probe enables more quantitative and comparable measurements of ER Ca2+.
• Resting ER Ca2+ concentration in primary dissociated neurons was found to be substantially lower than in embryonic fibroblasts.
• This finding highlights potential differences in calcium handling between neuronal and non-neuronal cell types.

Conclusions:

• The developed ratiometric probe is a valuable tool for advancing the quantitative study of ER Ca2+ homeostasis.
• The study reveals significant differences in basal ER Ca2+ levels between neurons and fibroblasts, impacting our understanding of cellular calcium dynamics.
• Further research can leverage this probe to explore ER Ca2+ dysregulation in various disease models.