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:
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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.