RT Journal Article
SR Electronic
T1 Transgenic Expression of Embryonic MAP2 in Adult Mouse Brain: Implications for Neuronal Polarization
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 3265
OP 3273
DO 10.1523/JNEUROSCI.16-10-03265.1996
VO 16
IS 10
A1 Kathryn M. Marsden
A1 Thierry Doll
A1 Jacqueline Ferralli
A1 Florence Botteri
A1 Andrew Matus
YR 1996
UL http://www.jneurosci.org/content/16/10/3265.abstract
AB The major neuronal microtubule-associated protein MAP2 is selectively localized in dendrites, where its expression is under strong developmental regulation. To learn more about its potential effects on neuronal morphogenesis and its sorting within the neuronal cytoplasm, we have raised transgenic mice that express high levels of the embryonic form, MAP2c, in the adult brain. One transgenic line expressed higher levels of MAP2c than endogenous adult MAP2. This had no detectable effect on either the arrangement or morphology of neurons, suggesting that although MAP2c is necessary for neuronal morphogenesis it is not involved in its regulation. Like endogenous adult MAP2, transgenic MAP2c was present in dendrites but not axons, indicating that the signal responsible for its cytoplasmic sorting is contained within the 1.5 kb of its coding sequence. In situhybridization with specific probes showed that transgenic MAP2c mRNA was limited to cell bodies. Thus, the dendritic localization of MAP2c protein cannot be the result of previous transport of its mRNA but must depend on a signal associated with the protein itself. Furthermore, because the amino acid sequence of MAP2c is present in all forms of MAP2, this signal is also contained within adult high-Mr MAP2 protein. This raises the possibility that, rather than the conventional scheme of mRNA sorting preceding protein localization, the transport of adult MAP2 mRNA into dendrites could depend on it being part of a translation complex in which the targeting signal is on the nascent protein.