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Myelin-associated glycoprotein in the central and peripheral nervous system of quaking mice
Abstract:
The myelin-associated glycoprotein (MAG) was quantitated in the CNS and PNS of quaking mice and the levels compared to the levels of myelin basic protein (MBP) and 2':3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) activity. In the brainstems of 36-day-old quaking mice, MBP, MAG, and CNPase were reduced to 12, 16, and 29% of control levels, respectively. In the sciatic nerves of the 36-day-old quaking mice, MBP and CNPase were 38 and 75% of control levels, respectively, whereas the concentration of MAG was unchanged or slightly increased. Similar quantitative results were obtained for the sciatic nerves and spinal roots of 7-month-old quaking mice. Immunoblots showed that the principal MAG band from the brainstems, sciatic nerves, and spinal roots of the quaking mice had a higher than normal apparent Mr. In addition, there was a minor component reacting with anti-MAG antiserum in the brainstems of the quaking mice that had a slightly lower Mr than control MAG and was not detected in the normal mice. The results for the quaking mice are compared with those from similar studies on other mutants with dysmyelination of the CNS and PNS.
Insights
Quaking mice show reduced myelin basic protein (MBP) and myelin-associated glycoprotein (MAG) in the CNS, but MAG levels are maintained in the PNS. These findings highlight differential myelin defects in this neurological mutant.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- Myelin-associated glycoprotein (MAG) is crucial for myelin maintenance in the central nervous system (CNS) and peripheral nervous system (PNS).
- The quaking mouse is a model organism exhibiting dysmyelination, characterized by defects in myelin development and maintenance.
Purpose of the Study:
- To quantify myelin-associated glycoprotein (MAG) levels in the CNS and PNS of quaking mice.
- To compare MAG levels with myelin basic protein (MBP) and 2':3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) in quaking mice.
- To investigate the molecular characteristics of MAG in quaking mice.
Main Methods:
- Quantitative analysis of MAG, MBP, and CNPase in brainstems and sciatic nerves of quaking and control mice.
- Immunoblotting techniques to analyze MAG protein expression and apparent molecular weight.
Main Results:
- In quaking mouse brainstems, MBP, MAG, and CNPase were significantly reduced compared to controls.
- In quaking mouse sciatic nerves, MBP and CNPase were reduced, while MAG levels remained unchanged or slightly increased.
- Immunoblots revealed altered apparent molecular weight of MAG in quaking mice, with an additional minor component in the brainstem.
Conclusions:
- Quaking mice exhibit distinct quantitative alterations of MAG in the CNS versus the PNS.
- The observed MAG abnormalities in quaking mice suggest specific molecular defects contributing to dysmyelination.
- These findings contribute to understanding the molecular basis of myelin disorders and provide a basis for comparison with other myelin mutants.