IIBBA   05544
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE BUENOS AIRES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
IgG differential glycosylation is regulated by a novel UDP-glucoseglucosyltransferase isoform in mice
Autor/es:
MARÍA BELÉN PRADOS; LA BLUNDA; JULIO CARAMELO; SILVIA MIRANDA
Lugar:
Viña del Mar-Chile
Reunión:
Congreso; 9th Latin American Congress of Immunology; 2009
Institución organizadora:
Latin American Congress of Immunology
Resumen:
<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman"; mso-bidi-language:AR-SA;} p.MsoBodyText, li.MsoBodyText, div.MsoBodyText {margin:0cm; margin-bottom:.0001pt; text-align:justify; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman"; mso-bidi-language:AR-SA;} @page Section1 {size:595.3pt 841.9pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> IgG differential glycosylation is regulated by a novel UDP-glucoseglucosyltransferase isoform in mice Prados MB, La Blunda J, Cortina ME, Caramelo J, Miranda S   About 10% of serum IgG is N-glycosylated in the variable region. This percentage varies in response to different stimuli, leading to beneficial/harmful effects to the host. UDP-glucoseglucosiltransferase (GT) is critical in preventing partially folded glycoproteins to abandon the endoplasmic reticulum. Employing a murine hybridoma, we demonstrated that IgG variable region N-glycosylation (measured by lectin-ELISA) and GT expression/activity are modulated by progesterone. However, N-glycosylation correlated with GT activity but not with GT expression. This prompted us to search for a GT isoform which could have been measured in the activity assay but was not detected in the western-blot. This hypothesis is supported by Arnold et al., who isolated two human cDNAs homologues of GT. We searched for mice homologues of these proteins and generated an antibody against the new protein (GT2).  Its specificity and that of the one used previously was analyzed by western-blot. Results showed at least two GT isoforms distinguishable by each antibody. We then cultured the cells with progesterone and observed a modulation of GT2 expression, consistent with the activity results previously observed. In conclusion, we demonstrated that hybridoma cells express two functional GT isoforms that are modulated by progesterone. GT2 might be responsible for the differential glycosylation of IgG.