, 2005, van der Walt et al., 2004 and Wang et al., 2008). Fgf20 is specifically expressed in the substantia nigra of the midbrain and the cerebellum, where it promotes survival of substantia nigra dopaminergic neurons, the neurons most affected in PD (Murase and McKay, 2006). Carriers of one of the Fgf20 polymorphisms buy VRT752271 also present diminished verbal episodic memory and a significantly enlarged hippocampal volume, suggesting that genetic variations

in Fgf20 also modulate brain structure and function in healthy subjects (Lemaitre et al., 2010). Lesions to the adult nervous system reactivate developmental processes such as the proliferation and differentiation of progenitors present at the site of injury. Members of the FGF family, in particular FGF2, are strongly involved in neuroprotection and repair in response to neural tissue damage. Expression of Fgf2 and Fgfr1 is upregulated in glial cells and neural stem cells after neuronal damage, and analysis of mice mutant for Fgf2 or Fgfr1 has shown that both genes are required for neuronal regeneration following epileptic episodes, transient ischemia, or traumatic brain injury (Fagel et al., 2009 and Yoshimura et al., 2001).

Exogenous FGF2, alone or in combination with other factors such as brain-derived neurotrophic factor (BDNF) or EGF, also promotes learn more significant neuronal regeneration following neuronal loss induced not by epilepsy or ischemia

or in genetic models of neurodegenerative diseases such as Huntington’s disease (HD) (Jin et al., 2005 and Nakatomi et al., 2002). FGF2 appears to enhance the proliferation and differentiation of endogenous progenitor cells present in the dentate gyrus (e.g., in mice with hippocampal lesions) and in the subventricular zone (in HD mice) as well as outside these neurogenic regions. Exogenous or endogenous FGF2 also has a role in protection against neuronal death, notably in mouse models of neurodegenerative diseases such as HD or PD (Jin et al., 2005 and Timmer et al., 2007). The mammalian nervous system has, however, a limited capacity for self-repair. Efforts are being made to circumvent this limitation and boost the repair process by transplanting exogenous cells into sites of injury. FGFs can be used to generate, expand, and differentiate neurons in vitro and therefore have a major role to play in such cell replacement therapies (Figure 8). Pluripotent mouse embryonic stem (ES) cells self-renew indefinitely in culture when exposed to the cytokine leukemia inhibitory factor (LIF), but they can differentiate into neurons under the influence of endogenous FGF. ES cells produce FGF4, which, if left unchecked, acts in an autocrine/paracrine manner to block self-renewal and promote commitment to the mesodermal or neural lineages.