My pilot studies suggest that (I) Schwann cells undergo programmed cell death in vitro when cultured at low cell density; (II) that this has not been noticed previously because Schwann cells secrete autocrine survival factor(s) that prevent their death in routine medium / high density cultures, and (III) that neuregulins and neurotrophins might support Schwann cell survival. In this project I plan to confirm, analyse and extend these observations.
Firstly, the mechanisms of cell death will be further studied using in situ hybridization and ultrastructural studies, and the death will be quantified with respect to cell density, time in vitro and type of culture substrate. Secondly, growth factors will be screened for their ability to block Schwann cell death, with particular emphasis on neuregulins and neurotrophins. Thirdly, I will aim to identify the autocrine survival promoting activity present in Schwann cell conditioned medium using blocking antibodies and ligand trap methods. Fourthly, the developmental expression of relevant receptors and their regulation will be investigated. Lastly, if time allows I will seek to interfere with the expression of functional receptors by overexpression of dominant negative mutations.