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Updated: Jun 2, 2026
Visualizing and Tracking Endogenous mRNAs in Live Drosophila melanogaster Egg Chambers
Published on: June 4, 2019
In vivo imaging of labelled endogenous β-actin mRNA during nucleocytoplasmic transport
David Grünwald1, Robert H Singer
1Kavli Institute of NanoScience, Department of BioNanoScience, TU Delft, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
Abstract:
Export of messenger RNA occurs via nuclear pores, which are large nanomachines with diameters of roughly 120 nm that are the only link between the nucleus and cytoplasm. Hence, mRNA export occurs over distances smaller than the optical resolution of conventional light microscopes. There is extensive knowledge on the physical structure and composition of the nuclear pore complex, but transport selectivity and the dynamics of mRNA export at nuclear pores remain unknown. Here we developed a super-registration approach using fluorescence microscopy that can overcome the current limitations of co-localization by means of measuring intermolecular distances of chromatically different fluorescent molecules with nanometre precision. With this method we achieve 20-ms time-precision and at least 26-nm spatial precision, enabling the capture of highly transient interactions in living cells. Using this approach we were able to spatially resolve the kinetics of mRNA transport in mammalian cells and present a three-step model consisting of docking (80 ms), transport (5-20 ms) and release (80 ms), totalling 180 ± 10 ms. Notably, the translocation through the channel was not the rate-limiting step, mRNAs can move bi-directionally in the pore complex and not all pores are equally active.
Insights
Messenger RNA (mRNA) export dynamics at nuclear pores were resolved using super-resolution microscopy. This reveals a three-step process: docking, transport, and release, with translocation not being the rate-limiting step.
Area of Science:
- Cell Biology
- Molecular Biology
- Biophysics
Background:
- Nuclear pores are essential for messenger RNA (mRNA) export, connecting the nucleus and cytoplasm.
- The precise dynamics and selectivity of mRNA export through nuclear pores remain poorly understood.
- Conventional light microscopy limits the resolution needed to study these rapid nanoscale events.
Purpose of the Study:
- To develop a super-resolution microscopy technique for precise measurement of molecular distances and dynamics.
- To spatially and temporally resolve the kinetics of mRNA transport at nuclear pores in living cells.
- To elucidate the step-by-step mechanism and kinetics of mRNA export.
Main Methods:
- Developed a super-registration approach using fluorescence microscopy.
- Achieved 20-ms time precision and 26-nm spatial precision for capturing transient interactions.
- Applied the method to study mRNA transport kinetics in mammalian cells.
Main Results:
- A three-step model for mRNA export was established: docking (80 ms), transport (5-20 ms), and release (80 ms), totaling 180 ± 10 ms.
- mRNA translocation through the nuclear pore channel was found not to be the rate-limiting step.
- Observed bidirectional movement of mRNAs within the pore complex and varying pore activity levels.
Conclusions:
- The developed super-registration microscopy enables high-precision analysis of molecular dynamics in living cells.
- The study provides the first detailed kinetic model of mRNA export through nuclear pores.
- Findings challenge previous assumptions about the rate-limiting steps and dynamics of mRNA nuclear export.
