Expression of the transcription factor GADD153 is an indicator of apoptosis for recombinant Chinese hamster ovary (CHO) cells

Loss of cell viability, through engagement of apoptotic cell death, represe nts a limitation to maintenance of high levels of productivity of recombina nt animal cells in culture. The ability to monitor the status of recombinan t cells, and to define indicators of their "well-being," would present a va luable approach to permit a rational intervention at appropriate times duri ng culture. Growth arrest and DNA damage gene 153 (GADD153) is a member of the CCAAT/enhancer-binding protein (C/EBP) family of transcription factors and has been associated with apoptosis. We have examined the expression of GADD153 in conditions associated with apoptosis of recombinant CHO cells in batch culture. GADD153 expression is very low in CHO cells growing in the exponential phase of batch culture but is activated as cells enter the decl ine phase. Depletion of nutrients (glucose or glutamine) causes activation of GADD153 expression as does the imposition of endoplasmic reticulum stres s. In all cases, there is a good relationship between the extent of apoptos is that occurs in response to each stress and the degree of GADD153 express ion. In addition, nutrient refeeding or reversal of stress produces a conco mitant decrease in expression of GADD153 and the susceptibility to apoptosi s. Thus, GADD153 appears to offer a valid indicator of apoptosis and illust rates the potential for definition of monitors of cellular status related t o the likelihood of apoptosis of cell populations. (C) 2001 John Wiley & So ns, Inc.