Regulation of Neurotrophin-3 Expression by Epithelial- Mesenchymal Interactions: The Role of Wnt Factors
Ardem Patapoutian,
1*
Carey Backus,
2
Andreas Kispert,
3
Louis F. Reichardt
12
Neurotrophins regulate survival, axonal growth, and target
innervation of sensory and other neurons. Neurotrophin-3 (NT-3) is
expressed specifically in cells adjacent to extending axons of dorsal
root ganglia neurons, and its absence results in loss of most of these
neurons before their axons reach their targets. However, axons are not
required for NT-3 expression in limbs; instead, local signals from
ectoderm induce NT-3 expression in adjacent mesenchyme. Wnt factors
expressed in limb ectoderm induce NT-3 in the underlying mesenchyme.
Thus, epithelial-mesenchymal interactions mediated by Wnt factors
control NT-3 expression and may regulate axonal growth and guidance.
1 Department of Physiology,
2 Howard Hughes Medical Institute, University of
California, San Francisco, CA 94143-0723, USA.
3 Department of Molecular Embryology,
Max-Planck-Institute for Immunobiology, Stuebeweg 51, D-79108 Freiburg,
Germany.
*
To whom correspondence should be addressed. E-mail:
ardem{at}itsa.ucsf.edu
