Journal of Neuroscience, Vol 5, 977-991, Copyright © 1985 by Society for Neuroscience
Differences in the developmental patterns of three microtubule- associated proteins in the rat cerebellum
R Bernhardt, G Huber and A Matus
The developmental distribution patterns of microtubule-associated proteins
(MAPs) 1, 2, and 3 were studied using three monoclonal antibodies.
Immunochemical staining at the light and electron microscopic levels
demonstrated the specific localization of each MAP in different cellular
and subcellular compartments. MAP2, which is specifically associated with
dendritic microtubules in the adult brain, is strictly associated with
growing dendrites from the onset of their formation. MAP3, a recently
described MAP of Mr = 180,000, which in the adult brain is associated with
neurofilament-rich axons and glial processes, is associated with axons from
the beginning of outgrowth. Although MAP3 is not detectable in granule
cells and their parallel fiber axons in the mature cerebellum, it does
appear transitorily in these axons during development. During neuronal
differentiation, MAP1 is found first in axons and only later in dendrites
where the highest concentrations are eventually to be found. These results
indicate that the combined appearance of MAP1 and MAP2 (dendrites) or MAP1
and MAP3 (axons) correlates with the appearance of morphologically distinct
microtubules and provide further evidence that specific MAPs are molecular
determinants of dendritic and axonal formation.
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