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Suppression of MAP2 in cultured cerebellar macroneurons inhibits minor neurite formation
A Caceres1, J Mautino, K S Kosik
1Instituto de Investigacion Medica Mercedes y Martin Ferreyra, Cordoba, Argentina.
Abstract:
We show here that antisense MAP2 oligonucleotides inhibit neurite outgrowth in cultured cerebellar macroneurons. Unlike control neurons, which first extend a lamellipodial veil followed by a consolidation phase during which the cells extend minor neurites, MAP2-suppressed cells persist with lamellipodia and later become rounded. The induction of microtubules containing tyrosinated tubulin, which parallels neurite outgrowth in control neurons, was blocked under antisense conditions. The small but significant increase in acetylated microtubules was not affected. In contrast, the suppression of tau, which selectively blocks axonal elongation, completely prevented the increase of acetylated microtubules, but did not modify the induction of labile microtubules. These results suggest that MAP2 and tau have different functions: the initial establishment of neurites depends upon MAP2, whereas further neurite elongation depends upon tau and microtubule stabilization.
Insights
Microtubule-associated protein 2 (MAP2) is crucial for initial neurite outgrowth in neurons. Suppression of MAP2 prevents neurite extension, while tau is essential for further elongation and microtubule stabilization.
Area of Science:
- Neuroscience
- Cell Biology
- Molecular Biology
Background:
- Neurite outgrowth is a fundamental process in neural development.
- Microtubule-associated proteins (MAPs) play critical roles in neuronal structure and function.
- MAP2 and tau are key MAPs involved in microtubule dynamics.
Purpose of the Study:
- To investigate the distinct roles of MAP2 and tau in neurite outgrowth and microtubule dynamics in cultured cerebellar macroneurons.
Main Methods:
- Utilized antisense oligonucleotides to suppress MAP2 and tau expression in cultured neurons.
- Observed and quantified neurite outgrowth and morphological changes.
- Analyzed microtubule composition, specifically tyrosinated and acetylated tubulin, using immunofluorescence.
Main Results:
- Antisense MAP2 oligonucleotides inhibited initial neurite outgrowth, leading to persistent lamellipodia and cell rounding.
- MAP2 suppression blocked the induction of tyrosinated tubulin microtubules, essential for neurite extension.
- Tau suppression selectively inhibited axonal elongation and prevented the increase in acetylated microtubules, without affecting labile microtubules.
Conclusions:
- MAP2 is essential for the initial establishment of neurites.
- Tau is required for subsequent neurite elongation and microtubule stabilization.
- MAP2 and tau exhibit distinct, sequential functions in neuronal morphogenesis.