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Ex Utero Electroporation and Organotypic Slice Cultures of Embryonic Mouse Brains for Live-Imaging of Migrating GABAergic Interneurons
Published on: April 20, 2018
Synemin isoforms during mouse development: multiplicity of partners in vascular and neuronal systems
Araksya Izmiryan1, Claudio Areias Franco, Denise Paulin
1UPMC Univ Paris 06, UMR 7079, F-75005, Paris, France.
Abstract:
The intermediate filament (IF) synemin gene encodes three IF proteins (H 180, M 150, L 41 kDa isoforms) with overlapping distributions. In the present study we analysed the mRNA and protein expression of each isoform in developing mouse embryos. Synemin M mRNA was present as early as E5 with vimentin and nestin. Synemin H was found later at E9 in the nervous system and mesodermic derivatives concomitantly with angiogenesis, somitogenesis and the migration of neural crest cells. Synemin L appeared later in neurons at E15. Furthermore, the synemin isoforms required different IF partners depending on the cell type to form filamentous structures. In endothelial cells, synemin H/M were found associated with vimentin and were absent in vimentin-null mice. In neurons of the peripheral nervous system of E15 embryos, synemin H/M or L were co-expressed with neurofilament, peripherin and internexin. In adult mice, our data support the existence of different subpopulations of neurons within the dorsal root ganglia: one composed of small neurons containing synemin H/M and peripherin, and another composed of large neurons containing synemin L and neurofilaments. Axons devoid of neurofilaments from mutant mice (NFHLacZ) showed an absence of the L isoform but contained H/M isoforms with peripherin.
Insights
The synemin gene produces three intermediate filament (IF) proteins. These isoforms exhibit distinct developmental timing and partner with different proteins, forming specific neuronal subtypes in the nervous system.
Area of Science:
- Cell Biology
- Developmental Biology
- Neuroscience
Background:
- The synemin gene encodes three intermediate filament (IF) protein isoforms (H, M, L) with overlapping expression patterns.
- Intermediate filaments are crucial for cellular structure and function, particularly in the nervous system.
Purpose of the Study:
- To analyze the mRNA and protein expression of synemin isoforms during mouse embryonic development.
- To investigate the interaction of synemin isoforms with other IF proteins in different cell types.
Main Methods:
- Quantitative real-time PCR for mRNA expression analysis.
- Immunohistochemistry and Western blotting for protein expression and localization.
- Analysis of knockout mouse models (vimentin-null and NFHLacZ).
Main Results:
- Synemin M mRNA is detected early (E5), coinciding with vimentin and nestin.
- Synemin H appears later (E9) in the nervous system and mesoderm, associated with developmental processes.
- Synemin L is detected even later (E15) in neurons.
- Synemin isoforms require specific IF partners: synemin H/M associate with vimentin in endothelial cells and are absent in vimentin-null mice.
- In peripheral neurons, synemin isoforms co-express with neurofilament, peripherin, and internexin.
- Distinct dorsal root ganglia neuron subpopulations identified: small neurons with synemin H/M and peripherin, large neurons with synemin L and neurofilaments.
- Mutant mice lacking neurofilaments show absence of synemin L but presence of synemin H/M with peripherin.
Conclusions:
- Synemin isoforms display differential temporal and spatial expression during mouse development.
- The assembly of synemin-containing IF requires cell-type-specific interactions with other IF proteins.
- Synemin isoforms contribute to the differentiation of distinct neuronal subpopulations in the dorsal root ganglia.
