Lamey, C., Glendining, K., Kreiman, G., Kang, N., Kuan, H., Fassler, R., Sawatari, A., Tonegawa, S., and Sur, M.

Differential Gene Expression between Sensory Neocortical Areas: Potential Roles for Ten_m3 and Bcl6 in Patterning Visual and Somatosensory Pathways.

Cerebral Cortex, In Press (2007) PDF

---

Adult neocortical areas are characterized by marked differences in
cytoarchitecture and connectivity that underlie their functional
roles. The molecular determinants of these differences are largely
unknown. We performed a microarray analysis to identify molecules
that define the somatosensory and visual areas during the
time when afferent and efferent projections are forming. We
identified 122 molecules that are differentially expressed between
the regions and confirmed by quantitative polymerase chain
reaction 95% of the 20 genes tested. Two genes were chosen for
further investigation: Bcl6 and Ten_m3. Bcl6 was highly expressed
in the superficial cortical plate corresponding to developing layer IV
of somatosensory cortex at postnatal day (P) 0. This had diminished
by P3, but strong expression was found in layer V pyramidal cells
by P7 and was maintained until adulthood. Retrograde tracing
showed that Bcl6 is expressed in corticospinal neurons. Ten_m3
was expressed in a graded pattern within layer V of caudal cortex
that corresponds well with visual cortex. Retrograde tracing and
immunostaining showed that Ten_m3 is highly expressed along
axonal tracts of projection neurons of the developing visual
pathway. Overexpression demonstrated that Ten_m3 promotes
homophilic adhesion and neurite outgrowth in vivo. This suggests
an important role for Ten_m3 in the development of the visual
pathway.