Download Is Neuronatin mRNA Dendritically localized in Hippocampal Neurons

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Is Neuronatin mRNA Dendritically Localized in Hippocampal Neurons?
Judy Samattasribootr
Mentor: Kelsey Martin
Synaptic plasticity is the capacity of neurons to alter the strength of their connections, and has been
shown to occur in a synapse-specific fashion. Alterations in synaptic strength occur during late stages
of brain development and in response to a variety of stimuli in the adult brain, including injury, drug
abuse, and learning and memory. Although short-term forms of plasticity involve post-translational
modifications of existing proteins, changes in gene expression are necessary for long-lasting effects.
One question that arises is how plasticity can occur in a spatially restricted manner, where certain
synapses can be altered while surrounding synapses on the same cell are unchanged. The dendritic
localization of polyribosomes and translational machinery suggests that local translation of mRNAs
at the synapse may play a role in synapse-specific forms of plasticity. To identify the population of
mRNAs that are localized at the synapse, a preparation of cultured rat hippocampal neurons was
developed in which neuronal processes could be mechanically separated from cell bodies. This
preparation was used as the starting material for a microarray analysis. The analysis identified a
number of candidate transcripts that may be dendritically localized. To confirm the localization of
the candidate genes, a series of in situ hybridizations were performed both in cultured neurons and in
cryostat sections of the brain. One of the identified genes, neuronatin-, was shown to be localized
to distal dendrites in cultured neurons. In the adult brain, neuronatin appears to be exclusively
expressed in the cell bodies and dendrites of CA2 and CA3 areas of the hippocampus as well as cells
in the periventricular zones. Future studies are necessary to determine the function of neuronatin and
its possible role in synaptic plasticity.