The microglial reaction in spinal cords of jimpy mice is related to apoptotic oligodendrocytes
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J M Vela1, I Dalmau, B González
1Department of Cell Biology and Physiology, Faculty of Medicine, Autonomous University of Barcelona, Spain.
Abstract:
Jimpy is a shortened life-span murine mutant whose genetic disorder results in a severe hypomyelination in the central neruons system associated with a variety of glial abnormalities, including oligodendrocyte death. In this study, we report that oligodendrocyte death in jimpy occurs through an apoptotic mechanism, as demonstrated by in situ labeling of nuclear DNA fragmentation. Compared to those of normal littermates, the spinal cords of jimpy mice showed a significantly higher number of apoptotic cells. Our observations also corroborate that specific glial cell death in jimpy is restricted to oligodendrocytes, as evidenced by double labeling for DNA fragmentation and MBP immunocytochemistry. Cells labeled for DNA fragmentation were always negative for astroglial or microglial markers. Apoptotic oligodendrocytes were not aggregated into clusters and were ubiquitously distributed throughout the jimpy spinal cord, although were more numerous in white matter than in gray matter. We found no physical association between astrocytes and dying cells in jimpy. Microglial cells, however, were found closely attached to and even surrounding apoptotic cells. The possible role of microglial cells in relation to apoptotsis is discussed.
Insights
The jimpy mouse model exhibits oligodendrocyte death via apoptosis, a key mechanism in its central nervous system hypomyelination. Microglial cells closely associate with these dying oligodendrocytes, suggesting a potential role in the disease process.
Area of Science:
- Neuroscience
- Cell Biology
- Genetics
Background:
- The jimpy mouse is a mutant with a shortened lifespan and severe central nervous system hypomyelination.
- This condition is characterized by glial abnormalities, prominently featuring oligodendrocyte death.
Purpose of the Study:
- To investigate the mechanism of oligodendrocyte death in the jimpy mouse model.
- To determine if glial cell death is specific to oligodendrocytes and to explore the role of other glial cells.
Main Methods:
- In situ labeling of nuclear DNA fragmentation to detect apoptosis.
- Double labeling using DNA fragmentation and myelin basic protein (MBP) immunocytochemistry.
- Analysis of glial cell markers (astrocytes, microglia) in conjunction with apoptotic cells.
Main Results:
- Oligodendrocyte death in jimpy mice occurs through apoptosis, evidenced by DNA fragmentation.
- Jimpy spinal cords show significantly more apoptotic cells than normal littermates.
- Apoptotic cells were confirmed as oligodendrocytes and not astrocytes or microglia.
- Apoptotic oligodendrocytes were distributed throughout the jimpy spinal cord, particularly in white matter.
- Microglial cells were observed attached to and surrounding apoptotic oligodendrocytes, while astrocytes showed no such association.
Conclusions:
- Oligodendrocyte death in the jimpy mutant is an apoptotic process.
- The observed glial abnormalities are specific to oligodendrocytes.
- Microglial cell interaction with apoptotic oligodendrocytes warrants further investigation into their role in jimpy pathogenesis.