Related Experiment Videos
Regulation of CD44 in the regenerating mouse facial motor nucleus
L L Jones1, G W Kreutzberg, G Raivich
1Department of Neuromorphology, Max Planck Institute of Psychiatry, Martinsried, Germany.
Abstract:
CD44 is a cell adhesion molecule which plays an important role in cell movement and adhesion, e.g. in lymphocyte homing and tumour metastasis. Here we studied the expression of CD44 mRNA and protein immunoreactivity in the facial nucleus after nerve injury and during the ensuing regeneration. Transection of the facial nerve led to a strong up-regulation of CD44, peaking 4 days after injury on the motoneurons of the axotomized facial nucleus. Use of the polymerase chain reaction confirmed the de novo expression of CD44 and detected only the standard haematopoietic CD44 isoform. Western blotting also detected the 76 kDa protein subtype, in line with the predicted size of the haematopoietic CD44 variant. At the ultrastructural level, CD44 immunoreactivity was restricted to the surface of the neuronal perikarya, their dendrites and axons. It was not seen in the adjacent activated astrocytes, microglia or vascular endothelia. This study shows strong up-regulation of the cell adhesion molecule CD44 on the regenerating motoneurons in the axotomized facial nucleus. These data suggest that CD44 may play a role in neurite outgrowth, in synaptic stripping or in the adhesion of activated glial cells to the perikaryal surface of the axotomized motoneurons.
Insights
The cell adhesion molecule CD44 is significantly upregulated on facial motoneurons after nerve injury. This suggests CD44 may aid in nerve regeneration processes like neurite outgrowth.
Area of Science:
- Neuroscience
- Cell Biology
- Regenerative Medicine
Background:
- CD44 is a cell adhesion molecule crucial for cell movement, lymphocyte homing, and tumor metastasis.
- Understanding cell adhesion molecule roles in nerve regeneration is vital for therapeutic development.
Purpose of the Study:
- To investigate the expression and localization of CD44 in the facial nucleus following nerve injury and during regeneration.
- To determine the specific CD44 isoform and protein subtype expressed after facial nerve transection.
Main Methods:
- Studied CD44 mRNA and protein expression in the facial nucleus post-nerve injury using polymerase chain reaction and Western blotting.
- Utilized ultrastructural analysis to pinpoint CD44 immunoreactivity localization on neuronal and glial cells.
Main Results:
- Facial nerve transection caused a significant upregulation of CD44, peaking at 4 days post-injury on axotomized motoneurons.
- Polymerase chain reaction confirmed de novo expression of the standard hematopoietic CD44 isoform.
- Western blotting identified the 76 kDa protein subtype, and ultrastructural analysis showed CD44 localized to neuronal surfaces, dendrites, and axons, but not on adjacent glial cells or vasculature.
Conclusions:
- Strong upregulation of CD44 occurs on regenerating motoneurons in the axotomized facial nucleus.
- CD44 may play a role in neurite outgrowth, synaptic stripping, or glial cell adhesion to motoneurons during nerve regeneration.