Super-resolution microscopy of mitochondrial mRNAs.

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Mitochondria possess their own DNA (mtDNA) and gene expression machinery.
• The spatial distribution of mitochondrial mRNA and proteins is poorly understood due to microscopy limitations.

Purpose of the Study:

• To develop and apply super-resolution microscopy techniques to visualize individual mitochondrial mRNA molecules and associated proteins.
• To investigate the spatial organization and dynamics of mitochondrial mRNA in response to cellular stress and disease.

Main Methods:

• Single-molecule fluorescence in situ hybridization (smFISH) combined with STED and MINFLUX super-resolution microscopy.
• Visualization of individual mitochondrial mRNA molecules and RNA-binding proteins.
• Analysis of mRNA distribution, shape, and proximity to ribosomes in mammalian cells.

Main Results:

• STED nanoscopy revealed spatial relationships between different mRNA species and proteins like GRSF1.
• Adaptive changes in mRNA distribution and quantity were observed in stressed cells and patient-derived cell lines.
• STED-smFISH showed mRNA release during apoptosis, and MINFLUX revealed mRNA folding and proximity to mitochondrial ribosomes.

Conclusions:

• Super-resolution microscopy enables visualization of mitochondrial mRNA and associated proteins at the single-molecule level.
• Mitochondrial mRNA distribution and organization are dynamic and adapt to cellular conditions, including apoptosis.
• These advanced imaging techniques provide new avenues for studying mitochondrial gene regulation in health and disease.