IDEHU   05542
INSTITUTO DE ESTUDIOS DE LA INMUNIDAD HUMORAL PROF. RICARDO A. MARGNI
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
IN VITRO MODULATION OF OLIGOSACCHARILTRANSFERASE EXPRESSION BY PROGESTERONE
Autor/es:
PRADOS MB., CARAMELO J. AND MIRANDA S.
Lugar:
Córdoba, Argentina
Reunión:
Congreso; III Latin American Symposium On Maternal Fetal Interaction-Placenta – Research And Clinical; 2007
Resumen:
Asymmetric antibodies (AAb) are antibodies that have an extra N-linked oligosaccharide in one of the two Fab regions. It has been demonstrated that progesterone (P4) can modulate its synthesis by a murine hybridome. However, the mechanisms involved in this regulation are not understood. Oligosaccharyltransferase (OST) is an integral membrane protein that catalizes N-linked glycosylation of nascent polipeptides in the lumen of the endoplasmic reticulum. Mammalian organisms express several OST isoforms. OST isoforms that incorporate STT3-B as a subunit are more active and has a reduced ability to discriminate between donor substrates than those OST that incorporate STT3-A. It has been suggested that differences in expression on the enzimatically distinct OST isoforms might provide an explanation for tissue specific glycan heterogeneity. To investigate the involvement of OST in AAb synthesis, here we studied the influence of progesterone on STT3-B and STT3-A expression in a murine hybridome able to secrete both symmetric and AAb. The cells were incubated with P4 (0, 10-5, 10-6, 10-8, 10-9  and 10-10M) for 48 hs. STT3-B and STT3-A expression was measured by western blot using two policlonal antibodies that specifically recognizes STT3-B or STT3-A in cells microsomal fraction. Results indicate that P4 10-8 M increased STT3-B expression (around 70%) while STT3-A expression was not modified. P4 10-9 M also augmented STT3-B expression but it diminished STT3-A expression. P4-10 M only diminished STT3-B (aprox. 70%). P4 -5 and -6 did not modify any of the isoforms´expression.  These preliminar results suggested that P4 might modulate OST activity, and in this way could be involved in immunoglobulins glycan heterogenity.