Induction of Glutamine Synthetase in Cultures of Embryonic Neural Retina

• Published in: The Journal of biological chemistry 1974-09, Vol.249 (18), p.6021-6023
• Main Authors: Jones, Richard E., Moscona, Malka H., Moscona, Aron A.
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(20)79920-5

Selected aspects of the induction of glutamine synthetase by hydrocortisone in cultures of embryonic neural retina were re-examined. The results clarify inconsistencies raised in a recent report (Schwartz, R. J. (1973) J. Biol. Chem. 248, 6426–6435). We show that (a) the extensive histological deterioration of retina cultures attributed to actinomycin D in the above report does not occur under our conditions and was presumably due to some suboptimal culture condition(s); (b) the kinetics of glutamine synthetase induction described in the above report are aberrant and therefore cannot be used as a basis for studies of regulatory processes; (c) contrary to the above report, glutamine synthetase in embryonic retina can be repeatedly induced and “deinduced” by consecutive application and withdrawal of the steroid inducer; (d) inadequate procedure may account for failures to obtain the characteristic effects of high and low concentrations of actinomycin D in this system. It appears that Schwartz's negative results reflected the pathology of deteriorating retina tissue cultures and therefore are not applicable to the analysis of normal regulatory mechanisms in the induction of glutamine synthetase. Our findings invalidate Schwartz's key arguments for criticizing previous studies on the induction of glutamine synthetase in the retina and on control mechanisms in other inducible enzyme systems.