Variations in endometrial expression of active and inactive forms of glycogen synthase kinase-3 β protein during the menstrual cycle

Abstract

Objective: Glycogen Synthase Kinase-3β (GSK-3β) is a serine/threonine kinase that plays a role in glycogen synthesis by inhibiting glycogen synthase (GS) through phosphorylation (Figure 1). We have previously reported on the expression of its total form in the female reproductive tract with highest expression being in the premenopausal endometrium. The objective of this investigation was to examine the expression of total and phosphorylated form (inactive) of GSK-3β in the premenopausal endometrium during the menstrual cycle. Based on our previous data we hypothesized that the inactive form of GSK-3β is preferentially expressed in the late proliferative through the secretory phase of the endometrium.