1: Development. 1997 Jul;124(14):2709-18. 

Inductive interactions direct early regionalization of the mouse forebrain.

Shimamura K, Rubenstein JL.

Department of Psychiatry and Langley Porter Psychiatric Institute, University of
California at San Francisco, 94143-0984, USA.

The cellular and molecular mechanisms that regulate regional specification of
the forebrain are largely unknown. We studied the expression of transcription
factors in neural plate explants to identify tissues, and the molecules produced
by these tissues, that regulate medial-lateral and local patterning of the
prosencephalic neural plate. Molecular properties of the medial neural plate are
regulated by the prechordal plate perhaps through the action of Sonic Hedgehog.
By contrast, gene expression in the lateral neural plate is regulated by
non-neural ectoderm and bone morphogenetic proteins. This suggests that the
forebrain employs the same medial-lateral (ventral-dorsal) patterning mechanisms
present in the rest of the central nervous system. We have also found that the
anterior neural ridge regulates patterning of the anterior neural plate, perhaps
through a mechanism that is distinct from those that regulate general
medial-lateral patterning. The anterior neural ridge is essential for expression
of BF1, a gene encoding a transcription factor required for regionalization and
growth of the telencephalic and optic vesicles. In addition, the anterior neural
ridge expresses Fgf8, and recombinant FGF8 protein is capable of inducing BF1,
suggesting that FGF8 regulates the development of anterolateral neural plate
derivatives. Furthermore, we provide evidence that the neural plate is
subdivided into distinct anterior-posterior domains that have different
responses to the inductive signals from the prechordal plate, Sonic Hedgehog,
the anterior neural ridge and FGF8. In sum, these results suggest that
regionalization of the forebrain primordia is established by several distinct
patterning mechanisms: (1) anterior-posterior patterning creates transverse
zones with differential competence within the neural plate, (2) patterning along
the medial-lateral axis generates longitudinally aligned domains and (3) local
inductive interactions, such as a signal(s) from the anterior neural ridge,
further define the regional organization.

PMID: 9226442 [PubMed - indexed for MEDLINE]


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