MAP2 and tau segregate into dendritic and axonal domains after the elaboration of morphologically distinct neurites: an immunocytochemical study of cultured rat cerebrum

Abstract

We sought to determine whether the strict segregation of MAP2 and tau into somatodendritic and axonal compartments in situ was maintained in dissociated neuronal cultures of the rat cerebrum. Cultures grown under serum-free conditions were immunolabeled with monoclonal antibodies specific for MAP2 and tau. At 14 d after plating, a clear distinction between MAP2- and tau-immunoreactive neurites was apparent. MAP2-immunoreactive neurites were relatively short, thick, tapering, and branched. Tau-immunoreactive neurites formed a crisscrossing meshwork of long, fine-caliber neurites, which, in more densely plated cultures, had a tendency to form thick, ropelike fascicles. Unlike the MAP2 pattern, tau antibodies labeled somata only lightly. Since distinct populations of neurites were labeled with the 2 antibodies, we sought to observe the development of the topographically distinct compartments by double-labeled immunocytochemistry with both polyclonal and monoclonal antibodies to MAP2 and tau. Cells observed within the first 8 hr after plating demonstrated equally intense MAP2 and tau immunoreactivity in a coextensive distribution throughout the cell body and initial neurites. By 16 hr, some neurites began to assume dendritic and axonal features; however, many such processes contained reaction product for both MAP2 and tau. Beginning at this time, neurites that appeared axonal showed a progressively weaker reaction with MAP2 antibodies, and neurites that appeared dendritic showed a progressively weaker reaction with tau antibodies. In most neurites the diminution appeared to occur uniformly over the entire extent of the neurite. During this transformation period there were occasional axon-like neurites that contained MAP2 immunoreactivity proximally, while tau immunoreactivity extended over the entire length of the neurite. We conclude that neurons in culture are able to compartmentalize MAP2 and tau into their appropriate processes and only attain an apparently homogeneous population of one of these MAPs after the neuron has assumed dendritic and axonal features. The analysis also lends indirect support to the hypothesis that microtubule-associated proteins (MAPs) form this association at the distal extent of the growing neurite.

Tau protein: An update on structure and function

“…Although a subsequent investigation suggested that tau protein could also be detected by tau1 in the somatodendritic compartment following phosphatase treatment of the tissue [Papasozomenos and Binder, 19871, the initial result localizing tau to axons has been confirmed by other investigators using a variety of polyclonal and monoclonal antibodies [Brion et al, 1988;Kosik and Finch, 1987;Trojanowski et al, 19891. The mechanism of this intracellular compartmentalization has yet to be elucidated.…”

NGF induces neonatal rat sensory neurons to extend dendrites in culture after removal of satellite cells

“…drites (Peng et al, 1986) and (4) the types of microtubuleFor all immunostaining experiments, cultures were fixed in 4% paraassociated proteins differ in axons and dendrites (Kosik and formaldehyde, 0.01% glutaraldehyde for 15 min in 0.1 M phosphate buffer (pH 7.4) and rinsed three times with Tris-buffered saline (5 mM Finch, 1987;reviewed by Matus, 1988). In particular, microTris, 0.9% NaCl, pH 7.4).…”

“…Cells were permeabilized by incubating the tubule-associated protein-2 (MAP2) and the mRNA that codes cultures in 100% methanol at -20°C for 15 min. After rinsing, the cells for it are found exclusively in cell bodies and dendrites (Carceres were incubated in Tris-buffered saline containing 5% normal goat serum Kosik and Finch, 1987;Kleiman et al, 1990) for 30 min. In the same solution, the primary antibodies were added whereas tau proteins are predominantly distributed in axons (HM-2, 1:5000; R4, l:lO,OOO; AP-20, 1:500; SM131, 1:20,000) for 1 hr at room temperature.…”

Anti-cancer drug induced neurotoxicity and identification of Rho pathway signaling modulators as potential neuroprotectants

“…Drug treated neurons were immunostained with both a well-established dendrite specific marker, MAP2, and an axonal specific marker, Tau-1 (Binder et al, 1986;Kosik and Finch, 1987). From our analyses, the MAP2 staining was the most sensitive marker for anti-cancer drug induced neurotoxicity in CNS neurons.…”

“…Tau-1 immunoreactivity was as expected, with staining largely isolated to the established axon (Fig 2A, arrow). In normal, developing neurons, MAP2 is increasingly segregated into the dendrites while microtubule-associated protein Tau localizes to the axon (Jones et al, 2004;Kosik and Finch, 1987). However, taxol effects on neurons were quite distinct.…”