en 27920883 <p>Background: It has been reported that secreted frizzled-related protein-4 known as an antagonist of Wnt signaling pathway plays a role in luteinization process of rodent granulosa cells. The purpose of this study was twofold: 1) to determine whether recombinant human secreted frizzled-related protein-4 (rhSFRP-4) could directly induce terminal differentiation of rat Granulosa Cells (GCs) and 2) to understand how the modulation of &beta;-catenin and Protein Kinase B (PKB)/AKT activity by exogenous SFRP-4 could be involved in steroidogenesis.<br /> Methods: GCs were firstly stimulated with Follicle-Stimulating Hormone (FSH) named as FSH-primed cells then were treated with luteinizing hormone (LH). Then estradiol (E₂) and progesterone (P₄) production levels were assessed in the absence or presence of rhSFRP-4 treatment. The expression levels of activated &beta;-catenin, pAKTser⁴⁷³, pGSK3&beta;ser⁹ were assessed by western blot or immuno-fluoresence.<br /> Results: In the presence of rhSFRP-4, there was 38% decreased E₂ levels compared to untreated FSH-primed cells (p&lt;0.05), and P₄ production subsequently decreased. However, in GCs pre-treated with rhSFRP-4 prior to addition of FSH, P₄ levels increased 2-fold compared with untreated cells (p&lt;0.05). Unexpectedly, treatment with rhSFRP-4 prior to LH stimulation inhibited LH-induced P₄ secretion. Treatment with low (0.5 <em>ng/ml</em>) but not high (50 <em>ng/ml</em>) concentrations of rhSFRP-4 led to significantly increased levels of pGSK3&beta;ser⁹ (1.6-fold) and nuclear active &beta;-catenin (2.8-fold) in GCs compared with untreated cells. Interestingly, pre-treating GCs with rhsFPR4 prior to LH stimulation resulted in a 38% decrease in pAKTser⁴⁷³ levels compared with those in LH-treated cells (p&lt;0.05).<br /> Conclusion: Taken together, our results showed that rhSFRP-4 could directly induce terminal differentiation in GCs via the modulation of &beta;-catenin and PKB/AKT pathways and that it does so in a dose-dependent manner.</p> Active β-catenin, GSK3β, PKB/AKT, Rat granulosa cell, Secreted frizzled-related protein-4 (SFRP-4) 159 168 https://www.ajmb.org/En/Article.aspx?id=252 https://www.ajmb.org/PDF/En/FullText/252.pdf GhamartajHosseinDepartment of Animal Physiology, Developmental Biology Laboratory, Faculty of Biology, University College of Science, University of Tehran, Tehran, Iran313ManijehKhanmohammadiReproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran1028ParissaSahranavard FardDepartment of Stem Cells & Developmental Biology at Cell Science Research Center, Royan Institute for Stem Cell Biology & Technology, ACECR, Tehran, Iran315YasamanHeidarianDepartment of Animal Physiology, Developmental Biology Laboratory, Faculty of Biology, University College of Science, University of Tehran, Tehran, Iran1030SomaiehKazemnejadReproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran64Mohammad MehdiAkhondiReproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran13