Mailhos, Carolina; (1994) Characterisation of apoptosis in the neuronal cell line, ND7/23. Doctoral thesis (Ph.D), UCL (University College London).

Text out.pdf Download (14MB)

Abstract

The process of programmed cell death or apoptosis plays a critical role in the development of the nervous system and ensures that the correct number of neurons are finally present (Wyllie et al, 1980). Post-mitotic neurons undergo programmed cell death, the extent of which is determined by the availability of trophic factors derived from the target field (Oppehneim 1991). However, early in development extensive cell death is observed when proliferating neuroblasts cease dividing and differentiate into mature non-dividing neurons and during adulthood when neuronal cell death occurs abnormally as a result of excitotoxicity, anoxia and ischemia (Robert-Lewis et a L, 1993). The neuronal cell line, ND7 (Wood et al., 1991), was used as a model system to analyze the processes involved in neuronal development. ND7 cells can be maintained in continuously growing culture in the presence of serum. When transferred to serum-free medium, the ND7 cells are induced to cease dividing and undergo morphological differentiation, acquiring numerous dendritic processes typical of differentiated neurons (Wheatley et al., 1991). Following transfer to serum-free medium a number of cells die rather than differentiate. Biochemical and morphological analysis confirmed that ND7 cells were dying by apoptosis when serum-starved (Wyllie et al., 1980). However, not all cells died when transferred to serum-free medium, suggesting that cells had the choice to either die or differentiate. Indeed, apoptosis can be regulated in ND7 cells. Addition of RA to differentiating cells enhanced cell death whereas addition of cAMP promoted both survival and differentiation. Furthermore, apoptosis was dependent on de novo protein synthesis and was inhibited by aurintricarboxylic acid which is known to inhibit the nuclease activity responsible for the DNA degradation characteristic of this mode of cell death. The heat shock response and the heat shock proteins (hsps) have been implicated in the protection of cells against a variety of stresses (Lindquist 1986; Lindquist and Craig 1988). Indeed, heat shock conferred ND7 cells protection against apoptosis. An increase in the level of hsp synthesis was paralleled by an increase in cell survival. Furthermore, heat shock protected neonatal rat primary dorsal root ganglia neurons from NGF deprivation, establishing the ND7 cell line as a suitable model to study the effects of heat shock on apoptosis in sensory neurons. To determine the role played by individual heat shock proteins in the protection against apoptosis, the two major inducible hsps, hsp90 and hsp70, were over expressed in ND7 cells. Cell lines over expressing either hsp90 or hsp70 showed no significant difference in survival following transfer to serum-free medium indicating that these hsp alone do not mediate the protective effect of heat stress. However, cell lines over expressing hsp90 and hsp70 were significantly more resistant to heat than the parental ND7 cells, showing for the first time that over expression of hsp70 and hsp90 can confer thermotolerance to neuronal cells.

Download activity - last month

Export as CSVXMLJSON

Download activity - last 12 months

Export as JSONXMLCSV

Downloads by country - last 12 months

Export as JSONCSVXML

Archive Staff Only

View Item