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Nuclear envelope budding enables large ribonucleoprotein particle export during synaptic Wnt signaling
Sean D Speese1, James Ashley, Vahbiz Jokhi
1Department of Neurobiology, University of Massachusetts Medical School, Worcester, 01605, USA.
Cell
|May 15, 2012
Summary
Large ribonucleoprotein (RNP) granules containing synaptic transcripts assemble in postsynaptic nuclei. These nuclear RNP granules exit the cell via nuclear envelope budding, a novel export pathway.
Area of Science:
- Cell Biology
- Neuroscience
- Molecular Biology
Background:
- Localized protein synthesis is crucial for cellular function.
- The assembly sites of large ribonucleoprotein (RNP) granules, essential for transport, were previously unknown.
- Synapse development involves the transport of specific protein transcripts.
Purpose of the Study:
- To identify the cellular location of large RNP granule assembly.
- To elucidate the mechanism of nuclear export for these large RNP granules.
Main Methods:
- Immunofluorescence microscopy to visualize RNP foci.
- Analysis of nuclear export pathways.
- Western blotting to detect protein phosphorylation.
Main Results:
- DFrizzled2, a Wnt-1 receptor fragment, forms large RNP granules within postsynaptic nuclei.
- These nuclear RNP granules contain synaptic protein transcripts.
- RNP granules exit the nucleus through a budding mechanism involving the nuclear envelope, similar to viral egress.
- Nuclear envelope budding is dependent on the phosphorylation of A-type lamin.
Conclusions:
- Postsynaptic nuclei serve as assembly sites for large RNP granules.
- Nuclear envelope budding represents an endogenous pathway for exporting large RNP granules.
- This mechanism provides new insights into nuclear export and its regulation.
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