CONICET | Buscador de Institutos y Recursos Humanos

In vitro modulation of UDP-glc-glucosiltransferase by progesterone. Study of the influence on the synthesis of asymmetric antibodies. M. Prados1, S. Litwin1, T. Gentile1, J. Caramelo2, S. Miranda1; 1IDEHU, Buenos Aires, Argentina, 2Fundaci¨®n Instituto Leloir, Buenos Aires, Argentina. Abstract:The role of UDP-glc-glucosiltransferase (GT) in the quality control of secretor proteins has been ascertained. However, its physiological relevance remains unknown. Two GT isoformes with different activity levels were described in human (HUGT1/ HUGT2), such isoformes were not reported in mouse. Here we studied the influence of progesterone (P4) on GT expression and activity, and on the synthesis of asymmetric antibodies (AAb) in a murine hybridome cell culture able to secrete symmetric and AAb. The cells were incubated with P4 (0, 10-5, 10-6, 10-8, 10-9M) for 48hs. GT activity was determined as the incorporation of [14C]-Glc to denatured thyroglobulin by microsomes. GT expression was measured by western blot using anti-rat antibody, which proved to recognise HUGT1 but not HUGT2. AAb rate was calculated by ELISA. GT activity in control cultures was 1.20 cpm/¦Ìg protein. When P4 was added at 10-6M, 10-8M and 10-9M the expression levels and activity were similar between each other (0.90, 0.77 and 0.96 cpm/¦Ìg protein; p>0.05). On the contrary, P4 10-5 M induced an increase in GT activity (1.43 cpm/¦Ìg protein, p<0.05 respect the other doses) and a decrease in the GT expression (-30 %; p<0,05). AAb rates observed for control, P4 10-5M, 10-6M, 10-8M and 10-9M were 36%, 30%, 15% (p<0.01), 36% and 29% respectively.These results are not conclusive about the participation of GT on the synthesis of AAb, but the discrepancies observed between GT expression and activity with P4 10-5M could suggest that P4 might regulate a switch of GT isoforms with different functions. :

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