Bmal1 deletion alters mitochondrial microstructure and function in mouse cone photoreceptors

Area of Science:

• Neuroscience
• Molecular Biology
• Ophthalmology

Background:

• The mammalian retina possesses an intrinsic circadian system governing ocular functions.
• The core clock gene Bmal1 deletion in mouse retinas disrupts retinal circuitry, cone spectral identity, and cone survival.
• Cone photoreceptors are metabolically demanding and vulnerable to oxidative stress and mitochondrial dysfunction.

Purpose of the Study:

• To investigate the role of Bmal1 in retinal mitochondrial biology.
• To analyze mitochondrial function and ultrastructure in Bmal1-deficient cells and retinas.

Main Methods:

• Analysis of mitochondrial respiration and ATP production in 661W cells and mouse retinas lacking Bmal1.
• Examination of mitochondrial inner-membrane organization and ultrastructure.
• Identification of transcriptional targets of BMAL1, including Mic60.

Main Results:

• Bmal1 deficiency led to impaired mitochondrial respiration and reduced ATP production.
• Loss of Bmal1 disrupted the organization of the mitochondrial inner membrane.
• Mic60, a regulator of mitochondrial cristae structure, was identified as a direct transcriptional target of BMAL1.

Conclusions:

• Bmal1 plays a critical role in maintaining mitochondrial integrity within the retina.
• Bmal1's regulation of mitochondrial function provides a potential explanation for reduced cone viability in Bmal1-deficient mice.
• Targeting Bmal1-mediated mitochondrial pathways may offer therapeutic strategies for retinal diseases.