AMH Signaling in Tissue Culture and in the Ovary; Prevention of Accelerated Follicle Growth through Interaction with Additional Follicle Activation Pathways

Introduction: AMH is a negative regulator of primordial follicles (PMF) activation, AMH is synthesized by granulosa cells in the ovary, the c-terminus active form binds AMHR2 with TGF-β type I receptor, phosphorylate intracellular SMAD1/5/8 and activate target genes. Receptor localization and post receptor cascade of AMH is not fully recognized, nor is the pathway by which AMH prevents PMF activation.

Aim: To study the effect of pharmacological administration of active AMH on ovarian follicle activation.

Materials and methods: Rodent and primate ovarian cell-lines or ovarian tissue exposed to activation processes (transplantation or alkylating agents) were introduced with human recombinant c-terminus AMH (hrAMH). Changes in AMH, AMHR2, pRPS6 and YAP were evaluated at the protein level by western blot on cell-lines or ovarian tissue. Localization of these proteins were visualized by immunohistochemistry.

Results: SMAD1/5/8 was phosphorylated by hrAMH in ovarian cell-lines and activated tissue, indicating activity of hrAMH on post receptor events. In addition, in tissue treated with alkylating agents known to induce PI3K/mTOR pathway upregulation, follicle activation and "Burn-Out" hrAMH downregulated PI3K/mTOR pathway towards inhibiting follicle activation. Transplantation of ovarian tissue fragments is accompanied with accelerated follicle growth, however, with hrAMH co treatment, prevented follicle growth and Hippo signaling downstream growth factors were translocated between nucleus and cytoplasm, suggesting AMH suppression effect on ovarian follicle activation.

Conclusion: Pharmacological administration of hrAMH suppress activation of PMF introduced by chemotherapy or transplantation of ovarian tissue graft mechanisms by suppressing additional activation pathways, such as PI3K/mTOR and Hippo signaling.