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Constitutive expression of p21H‐Ras val12 in neurons induces increased axonal size and dendritic microtubule density in vivo
Author(s) -
Seeger Gudrun,
Gärtner Ulrich,
Holzer Max,
Arendt Thomas
Publication year - 2003
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.10838
Subject(s) - microtubule , microbiology and biotechnology , genetically modified mouse , in vivo , transgene , biology , biochemistry , gene
The small G protein p21Ras is a key signal transducer mediating cellular growth and proliferation responses to extracellular stimuli. We investigated by electron microscopy the effects of augmented p21Ras activity on neuronal processes and microtubule arrangement in vivo. We used transgenic mice with a neuron‐specific overexpression of p21H‐Ras Val12 , which starts postnatally around Day 15. Axonal and dendritic diameters and the numerical density of dendritic microtubules were analyzed at postnatal Day 12 before the onset of transgene expression and in adult mice. In adult transgenic mice, calibers of both axons (corpus callosum) and dendrites (layers II/III of somatosensory cortex) were enlarged by about 57% and 79%, respectively. The increase in dendritic calibers was associated with an increment in the amount of microtubules. Even in dendrites of equivalent diameters, the number of microtubules was higher in transgenic mice compared to that in wild‐type mice suggesting an elevated microtubule density. Changes in process diameters or microtubule density were not observed at postnatal Day 12 before relevant transcription of transgenic p21H‐Ras Val12 . The present results extend previous findings on neuronal hypertrophy as a consequence of p21H‐Ras Val12 expression and suggest a profound influence on the dendritic microtubule network. © 2003 Wiley‐Liss, Inc.