Tetraspanin2 (Tspan2) is a member of the tetraspan/transmembrane4 superfamily restricted to the nervous system. The abundance of Tspan2 is low in physiological condition but increases greatly in myelin of PLP-deficient mice which may indicate its’ compensatory functions. Our experiments show that Tspan2 has no effect on delay of myelination at P14; young and old mice lacking Tspan2 has the same g-ratio as wild type. However, the quantity of unhealthy axons and axonal swellings are higher in aged animals lacking both PLP and Tspan2 than in single PLP knockout. Furthermore,the absence of PLP causes the decrease in the number of axons and rise in axon diameter; lack of
Tspan2 alone leads to decrease in quantity of 0.4-0.7 µm diameter axons in 40 weeks old mice. These findings point to a possible auxiliary role of Tspan2 in support of axonal transport and long-term axon preservation in PLP null condition.
Table of Contents
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
Animals
Electron and light microscopy
Morphometric analysis of electron micrographs
Quantification of myelinated vs. nonmyelinated axons
Validation of axon pathologies
g-ratio and axon diameter
Statistical analysis
RESULTS
Tspan-2 is not essential for myelination
g-ratio does not differ between wild type and Tspan2null mice
Axonal pathologies in aging mice
Quantity of axons decrease in PLPnull and Tspan2nullPLPnull mice
Axon diameter increase in absence of PLP
DISCUSSION
Objectives and Topics
The primary research objective of this laboratory rotation project is to investigate whether the protein Tetraspanin 2 (Tspan2) possesses compensatory functions for Proteolipid Protein (PLP) in the nervous system, specifically regarding the reduction of myelin delay or axonal degeneration in mice.
- Morphometric analysis of optic nerve cross sections
- Evaluation of axonal pathologies and degeneration
- Quantification of myelinated versus nonmyelinated axon populations
- Assessment of the g-ratio in Tspan2-deficient mice
- Investigation of Tspan2's potential neuroprotective role in PLP-deficient conditions
Excerpt from the Publication
Axonal pathologies in aging mice
We have evaluated optic nerves of 40 weeks old mice on presence of pathologies to see if Tspan2 protects axons against degeneration. Used categories are described above in “Materials and methods”. Figure 5 shows that single Tspan2null animals are not significantly different from WT in all categories. Mice lacking PLP have less healthy myelinated and more unmyelinated axons compared to WT. Also absence of Tspan2 in PLPnull has no additional effect on level of myelination in aging animals. PLP deficient mice have larger than in WT percentage of axons with increased adaxonal space, but there were no statistically significant difference between PLPnull and Tspan2nullPLPnull.
Axonal swellings are virtually absent in WT and Tspan2null mice but their amount increased up to 0.9 % in PLP and 1.2% in double knock out animals, which is significantly higher. Difference between PLPnull and Tspan2nullPLPnull is close to statistical significance (p=0,072) which might indicate a trend of having more axonal swellings in Tspan2nullPLPnull mice comparatively to PLPnull.
Percentages of unhealthy axons are significantly higher in Tspan2nullPLPnull in comparison with PLPnull mice (p = 0.001).The difference between these two groups and wild type is also significant.
Summary of Chapters
ABSTRACT: Summarizes the research focus on Tspan2 as a compensatory protein for PLP functions and highlights key findings regarding axonal preservation.
INTRODUCTION: Provides context on myelination, the role of PLP, and the scientific rationale for investigating Tspan2 as a candidate for neuroprotection.
MATERIALS AND METHODS: Details the experimental procedures, including animal models, microscopy techniques, and statistical methodologies applied.
RESULTS: Presents empirical data from the morphometric analysis, covering myelination status, axon diameter, and the prevalence of axonal pathologies.
DISCUSSION: Interprets the findings within the broader context of leukodystrophies and the potential regulatory roles of tetraspanins in CNS myelin.
Keywords
Tetraspanin 2, Tspan2, PLP, Proteolipid protein, Myelination, Axonal degeneration, Optic nerve, Morphometric analysis, Neuroprotection, CNS myelin, Axon pathology, Leukodystrophies, Oligodendrocytes
Frequently Asked Questions
What is the core subject of this research project?
The study examines the role of Tetraspanin 2 (Tspan2) in the nervous system, specifically evaluating its potential to compensate for the loss of Proteolipid Protein (PLP) in mice.
What are the central thematic areas?
The research covers myelin biology, axonal integrity, the impact of protein deficiencies on nerve health, and the structural morphology of optic nerves.
What is the primary research question?
The project seeks to determine if Tspan2 can reduce delays in myelination or mitigate axonal degeneration in mice that lack PLP.
Which scientific methods were utilized?
The study employed morphometric analysis of optic nerve cross sections, electron and light microscopy, and statistical evaluation using ANOVA and t-tests.
What topics are covered in the main body?
The main body covers the quantification of myelinated versus nonmyelinated axons, assessment of the g-ratio, and a detailed analysis of various axonal pathologies.
Which keywords best characterize this work?
Key terms include Tetraspanin 2, PLP, myelination, axonal degeneration, optic nerve, and neuroprotection.
How did Tspan2 deficiency affect P14 mice?
The results indicated that Tspan2 is not essential for myelination at this developmental stage, as no significant difference was observed compared to wild-type mice.
What specific pathologies were observed in aged PLP-deficient mice?
Aged mice lacking PLP exhibited increased axonal swellings, higher rates of unhealthy axons, and a significant reduction in total fiber quantity.
Did Tspan2 have a protective effect in double knockout mice?
While Tspan2 only slightly affected the state of axons, the increased prevalence of unhealthy axons in double knockout mice suggests that Tspan2 contributes to the maintenance of axonal transport.
- Citar trabajo
- Maryna Psol (Autor), 2012, Tetraspanin2 is a candidate for compensation of PLP functions, Múnich, GRIN Verlag, https://www.grin.com/document/233026
