Immuno-detection of mRNA-binding protein complex in human cells under transmission electron microscopy

Area of Science:

• Molecular Biology
• Cell Biology
• Biophysics

Background:

• Messenger RNA (mRNA) undergoes crucial processing events during its transit from the nucleus to the cytoplasm.
• mRNA interacts with proteins to form messenger ribonucleoprotein complexes (mRNPs) during these processes.
• Current imaging techniques can track mRNA localization but not the conformation of mRNPs within cells.

Purpose of the Study:

• To visualize the three-dimensional structure of mRNA-protein complexes in human cells.
• To differentiate between mRNA-protein complex conformations in the nucleus versus the cytoplasm.
• To develop a method applicable to mammalian cells for studying mRNA structure and function.

Main Methods:

• Immuno-electron microscopy was employed to visualize mRNA-protein complexes in cultured human cells.
• Specific antibodies targeted the mRNA exon junction binding complex Y14 and its binding protein Upf2.
• Transmission electron microscopy was used to image and analyze gold particle patterns indicative of complex structure.

Main Results:

• Distinct linear and stacked gold particle aggregation patterns were observed, reflecting different mRNA-protein complex conformations.
• A linear aggregation pattern was exclusively observed across the nuclear membrane.
• A stacked aggregation pattern was detected specifically in the cytoplasm.

Conclusions:

• The developed immuno-electron microscopy method successfully visualizes mRNA-protein complex conformation in human cells.
• Distinct structural differences in mRNA-protein complexes exist between the nucleus and cytoplasm.
• This technique is applicable to various cell types, including mammalian cells, facilitating further research into mRNA processing and function.