CELL BIOLOGY OF THE NEURON Polarity ... - Tavernarakis Lab

Cell Biology of the Neuron: Polarity, Plasticity and Regeneration, Crete 2011
Investigating the Role of Nogo-A in the Maturation of
the Visual System
Anna Guzik-Kornacka, Vincent Pernet, Martin Schwab
Brain Research Institute, ETH and University Zurich, Switzerland
Nogo-A is well known as a myelin-associated protein which inhibits neuronal
regeneration and growth after injury. Apart from the expression in
oligodendrocytes, Nogo-A is also expressed in many central and peripheral
neurons during development, and in some populations of adult neurons. Not
much is currently known on the role of Nogo-A in neurons. Regulatory functions
for precursor migration and fiber growth, fasciculation and branching have been
shown, but neuronal Nogo-A functions at later stages are largely unclear. In the
cerebellum, Nogo-A expression is down-regulated in Purkinje cells at the time of
the establishment of synaptic contact with the parallel fibers and with neurons of
the deep cerebellar nucleus. Retinal ganglion cells (RGCs) also express high level
of Nogo-A during embryonic and postnatal development, whereas in adult RGCs
the expression is strongly diminished. The developmental downregulation of
Nogo-A in RGCs coincides with the maturation of the visual system. At birth,
retinal ganglion cell terminals from both eyes innervate overlapping territories in
the lateral geniculate nucleus (LGN), but segregate into distinct eye-specific
domains by postnatal day 8 (P8). Nogo-A/B and Nogo-66 receptor (NgR) have
been suggested to restrict visual cortex plasticity after the so-called critical
period. This is related in time to the myelination of cortical axons, suggesting that
oligodendrocyte-derived Nogo-A stabilizes these synaptic contacts. On the other
hand, a role of neuronal Nogo-A has not been directly studied, neither in the
visual cortex nor for the refinement of the retino-geniculate projections. We
hypothesize that neuronal Nogo-A may participate in the refinement of the eyespecific
retinal projections to the LGN. To test this hypothesis we investigated the
influence of systemic deletion or acute blockade of Nogo-A with a functionblocking
antibody on the maturation of retinogeniculate projections.
Presented by: Guzik-Kornacka, Anna
125
Poster No 043
Red Session