Optogenetically engineered Ca2+ oscillation-mediated DRP1 activation promotes mitochondrial fission and cell death

Area of Science:

• Cell Biology
• Mitochondrial Biology
• Calcium Signaling

Background:

• Mitochondrial dynamics are crucial for cellular health and function.
• Calcium ions (Ca2+) are key regulators of mitochondrial activity and signaling.
• Existing methods for manipulating calcium signaling lack precise temporal control.

Purpose of the Study:

• To investigate the impact of optogenetically engineered calcium (Ca2+) signaling on mitochondrial dynamics.
• To explore the potential of light-controlled Ca2+ oscillations to modulate mitochondrial fission and related cellular processes.
• To provide a novel, temporally precise method for controlling mitochondrial fission.

Main Methods:

• Utilized optogenetics to engineer specific Ca2+ oscillation waves through customized illumination.
• Modulated light parameters (frequency, intensity, exposure time) to alter Ca2+ signaling.
• Assessed mitochondrial morphology, function, autophagy, and cell death.
• Investigated the phosphorylation status of dynamin-related protein 1 (DRP1) at Ser616 and Ser637.
• Examined the activation of Ca2+-dependent kinases (CaMKII, ERK, CDK1) and calcineurin phosphatase.
• Analyzed the expression levels of mitochondrial fusion proteins (MFN1, MFN2).

Main Results:

• Increased light frequency, intensity, and exposure time induced Ca2+ oscillations that drove mitochondria toward fission.
• Optogenetic Ca2+ signaling promoted mitochondrial dysfunction, autophagy, and cell death.
• Illumination triggered DRP1 phosphorylation at Ser616 via CaMKII, ERK, and CDK1 activation.
• Calcineurin phosphatase was not activated to dephosphorylate DRP1 at Ser637.
• Mitochondrial fusion protein expression (MFN1, MFN2) remained unaffected by light illumination.

Conclusions:

• Optogenetically engineered Ca2+ signaling provides a highly precise method for controlling mitochondrial fission.
• This approach enables temporal control over mitochondrial dynamics, offering advantages over pharmacological interventions.
• The study elucidates a novel mechanism involving Ca2+-dependent kinases in regulating DRP1 phosphorylation and mitochondrial fission.