Assembly Properties of Lamprey Neurofilament Subunits and Their Expression After Spinal Cord Transection

J Comp Neurol, 2011 · DOI: 10.1002/cne.22673 · Published: December 15, 2011

Simple Explanation

This study investigates the assembly properties of lamprey neurofilaments (NFs) and their expression patterns following spinal cord injury in lampreys. It challenges the previous belief that lampreys have only one NF subunit, NF180, and explores the roles of newly identified subunits in NF assembly and axonal regeneration. The research demonstrates that lamprey NFs, similar to those in mammals, require multiple subunits for proper assembly. Specifically, L-NFL (lamprey NFL homolog) is essential for filament formation, and the full length of NF180 is required for the formation of thick NF bundles. Furthermore, the study reveals that the expression of NF subunits is affected by spinal cord transection, with a decrease in expression followed by a recovery in neurons that have a high probability of axonal regeneration, suggesting a potential role for NFs in the regeneration process.

Study Duration

2-10 weeks

Participants

15 wildtype larval lampreys

Evidence Level

Not specified

Key Findings

1
Lamprey NFs require multiple subunits for assembly, including L-NFL (a lamprey NFL homolog) and NFM-like subunits (NF95, NF132, and NF180).
2
L-NFL is essential for filament formation, and none of the lamprey NF proteins could self-assemble into filament networks either at 37°C or 28°C.
3
The full length of NF180 is necessary for the formation of thick NF bundles, while the amino-terminal head and core domains are essential for assembly, but the carboxyl-terminal is essential for normal network appearance.

Research Summary

This study investigates the assembly properties of lamprey neurofilaments (NFs) and their expression following spinal cord transection. The findings challenge the previous assumption that lampreys possess only one NF subunit, NF180. The results indicate that lamprey NFs, similar to mammalian NFs, require multiple subunits for proper assembly. L-NFL is found to be essential for filament formation, and NF180's full length is needed for thick bundle formation. Expression patterns of NF subunits are altered after spinal cord injury, with a subsequent recovery in neurons exhibiting a high likelihood of axonal regeneration, supporting the hypothesis that NFs play a role in axonal regeneration mechanisms.

Practical Implications

Understanding NF Assembly

Provides insights into the molecular mechanisms governing neurofilament assembly in lampreys, which can be compared to those in mammals.

Axonal Regeneration

Supports the hypothesis that NFs play a role in axonal regeneration, which has implications for developing therapies for spinal cord injuries.

Evolutionary Conservation

Highlights the evolutionary conservation of NF structure and function across species, suggesting fundamental roles for these proteins in neuronal function.

Study Limitations

1
The study is limited to in vitro experiments and observations in lampreys, and the results may not be directly applicable to other species.
2
The precise mechanisms by which NFs contribute to axonal regeneration remain unclear.
3
The identity of a previously reported 50 kDa lamprey neurofilament protein (nlF50) remains unknown.

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