Identification of signaling pathways controlling survival of pancreatic beta-cells in diabetesLupše, Blaž (Avtor) Kreft, Marko (Mentor) Maedler, Kathrin (Komentor) PHLPP12/mTORYAPHippo pathwayMST1beta-cellspancreasdiabetesB Both, type 1 (T1D) and type 2 (T2D) diabetes mellitus involve the loss of functional insulin-producing beta-cell mass, where autoimmunity in T1D and apoptotic signalling in T2D are main causes for beta-cell death but their underlying mechanisms are poorly understood. In this thesis, we have investigated several interconnected signaling pathways controlling pancreatic beta-cell function and survival in diabetes. We have found that: (I) small molecule inhibitor of Hippo kinase MST1 improved beta-cell survival in human islets and in an established beta-cell line in vitro. (II) Islet-overexpression of the Hippo terminal effector YAP protects beta-cells from apoptosis triggered by multiple diabetogenic conditions. (III) mTORC1 signaling is activated in isolated islets from diabetic mouse models and its genetic and pharmacological suppression improved beta-cell function. (IV) PHLPP 1 and 2 phosphatases promote beta-cell dysfunction and death, and are regulated by mTORC1 signaling under diabetic conditions in beta-cells. These analyses confirm the importance of Hippo pathway components (MST1 and YAP) for the regulation of β-cell survival in diabetes. Also, mTORC1 has been identified as novel regulator of the PHLPP-MST1 signaling axis, which is highly activated under a diabetic milieu, suggesting a novel Hippo-dependent cellular program, regulated by PHLPP and mTOR1 signaling, which balances beta-cell homeostasis.[B. Lupše]20172017-12-21 07:15:35Magistrsko delo/naloga99016sl