Prenatal ontogeny of the epidermal growth factor receptor and its ligand, transforming growth factor alpha, in the rat brain

Abstract

Transforming growth factor alpha (TGF alpha) interacts with the epidermal growth factor receptor (EGF-R) to produce its biological effects. TGF alpha induces the proliferation and differentiation of central nervous system (CNS) astrocytes and pluripotent stem cells, as well as the survival and differentiation of postmitotic CNS neurons. Both TGF alpha and EGF-R have been localized to the postnatal CNS. As the majority of CNS neuronal proliferation and migration occurs antenatally, we have examined the ontogeny of TGF alpha and EGF-R in the embryonic rat brain by in situ hybridization. EGF-R mRNA was expressed in the brain as early as embryonic day 11 (E11; the earliest age examined). It was initially detected in the midbrain, with subsequent expression first in multiple germinal zones, followed by expression in numerous cells throughout the brain. In many brain areas, EGF-R mRNA appeared in germinal centers during the later stages of neurogenesis and the early stages of gliogenesis. In the midbrain, the distribution of EGF-R mRNA overlapped extensively with that of tyrosine hydroxylase mRNA, suggesting that fetal dopaminergic neurons express EGF-R. Immunocytochemistry was used to demonstrate the presence of EGF-R-immunoreactive protein in brain areas that expressed EGF-R mRNA on E15 and E20. The expression of TGF alpha in many brain structures preceded that of EGF-R mRNA. TGF alpha mRNA was distributed throughout many non-germinal centers of the brain on E12 and later. Some brain areas, such as the external granule cell layer of the cerebellum, expressed EGF-R, but not TGF alpha mRNA. Northern blot analysis demonstrated that mRNA species for both TGF alpha and EGF-R were similar in embryos and adults. These data indicate that TGF alpha and EGF-R are positioned to have a role in the genesis, differentiation, migration, or survival of numerous cell populations in the embryonic brain.

Neonatal perturbation of neurotrophic signaling results in abnormal sensorimotor gating and social interaction in adults: implication for epidermal growth factor in cognitive development

“…[1][2][3]44 EGF production declines during brain development, while expression of HB-EGF and TGFa is increased. 45,46 In fact, EGFR are expressed on pyramidal neurons, interneurons, and glial cells in the postnatal neocortex and striatum, suggesting that they have biological actions in these cells. 47,48 Herein, we demonstrated that peripherally administered EGF can act over and above endogenous EGF in the brain as monitored by phosphorylation of EGFR.…”

Cellular Therapy and Induced Neuronal Replacement for Huntington's Disease

“…Neural stem cells from the adult subventricular zone can be expanded and maintained in vitro under the influence of fibroblast growth factor 2 (FGF2) and epidermal growth factor (EGF); these observations suggested that FGF2 and EGF might also act in vivo [84][85][86][87][88]. Indeed, knockout mice for FGF2 or transforming growth factor-α, a ligand for EGF receptor, exhibit decreased neurogenesis in the SVZ, and fewer neurons recruited to the olfactory bulb [89,90].…”

Involvement of a Rac Activator, P-Rex1, in Neurotrophin-Derived Signaling and Neuronal Migration

“…Another tyrosine kinase receptor, EGFR, is also implicated in the regulation of radial migration in the developing cerebral cortex. EGFR and its ligands, including heparin-binding EGF (HB-EGF) and TGF␣, are expressed in the developing cortex (Kornblum et al, 1997;Nakagawa et al, 1998). EGFR-targeted disruption and EGFR overexpression studies showed that EGFR is involved in normal radial migration (Threadgill et al, 1995;Caric et al, 2001).…”