The Journal of Neuroscience, December 1, 2001, 21(23):9345-9354
Lymnaea Epidermal Growth Factor Promotes Axonal
Regeneration in CNS Organ Culture
Willem C.
Wildering,
Petra M.
Hermann, and
Andrew G. M.
Bulloch
Department of Physiology and Biophysics, Neuroscience Research
Group, Faculty of Medicine, Health Sciences Center, University
of Calgary, Calgary, Alberta, Canada, T2N 4N1
Members of the epidermal growth factor (EGF) family are frequently
implicated in the injury response of the mammalian nervous system.
Although this implication is supported by extensive molecular evidence,
it is not underpinned by conclusive functional data. Recently, we found
that expression of an EGF homolog from the pond snail Lymnaea
stagnalis (L-EGF) is upregulated after axotomy in the adult
CNS, suggesting a role for this molecule in the injury response of the
CNS. In the present study we asked whether L-EGF can promote axonal
regeneration of three types of identified neurons in organ-cultured
CNS. Treatment with purified L-EGF substantially enhanced axonal
regeneration of all three types of neurons, an effect inhibited
by submicromolar doses of PD153035, a specific EGF receptor (EGFR)
tyrosine kinase inhibitor. In addition, PD153035 and K252a, a
nonspecific kinase inhibitor, also reduced the degree of axonal
regeneration that occurs without L-EGF supplementation, indicating that
L-EGF or other EGFR ligands synthesized in the CNS participate in the
regenerative response. An intriguing aspect of these results is that
axonal regeneration of different, intrinsically L-EGF responsive and
unresponsive neurons occurred in a coordinated manner. This observation
suggests that indirect in addition to direct actions contribute to the
beneficial effect of L-EGF. In conclusion, we provide functional
evidence that an EGF homolog can promote axonal regeneration,
substantiating existing molecular evidence implicating the EGF family
in peripheral nerve regeneration and emphasizes the therapeutic
potential of these molecules.
Key words:
neurotrophic factor; epidermal growth factor; axonal
regeneration; invertebrate; mollusk; CNS; L-EGF; peripheral nerve
regeneration; neurotrauma
Copyright © 2001 Society for Neuroscience 0270-6474/01/21239345-10$05.00/0