BACKGROUND: Prohibitin (PHB), a protein located on the inner mitochondrial membrane and nuclei, is an intracellular effector of transforming growth factor-beta (TGF-beta) signaling in prostate cancer cells. This study investigated the involvement of PHB in the apoptosis and survival outcomes of human prostate cancer cell to TGF-beta. shRNA PHB loss of function in prostate cancer cells led to enhanced apoptotic response to TGF-beta via Smad-dependent mechanism. METHOD: TGF-beta activation of Raf-Erk intracellular signaling, led to PHB phosphorylation, decreased inner mitochondrial permeability, and increased cell survival. Calcein-based immunofluorescence studies revealed the functional involvement of PHB in maintaining inner mitochondrial membrane permeability as an integral component of TGF-beta induced apoptosis in prostate cancer cells. RESULTS: These finding indicates that induction of TGF-beta apoptosis is mediated by Smad-dependent and Smad-independent signaling (MAPK) converging at PHB as a downstream effector regulating inner mitochondrial permeability. Putative PHB associated proteins were identified by subjecting TGF-beta treated cells to immunoprecipitation with anti-PHB, and mass spectrometry. A screen for the kinase specific phosphorylation sites of PHB revealed three protein kinase (PKC) binding sites. CONCLUSION: Our results demonstrate that TGF-beta led to upregulation of the PKC inhibitor 14-3-3 protein and promoted its association with PHB, while PHB association with PKC-delta, was inhibited by the MEK1 inhibitor, documenting a critical interdependence between the MEK-ERK signaling and prohibitin phosphorylation. These findings suggest a dual role for PHB as a downstream determinant of the cellular response to TGF-beta via Smad-dependent pathway (apoptosis) and MAPK intracellular signaling (survival).
We have not found any resources mentioned in this publication.
SciCrunch® is a data sharing and display platform. Anyone can create a custom portal where they can select searchable subsets of hundreds of data sources, brand their web pages and create their community. SciCrunch® will push data updates automatically to all portals on a weekly basis. User communities can also add their own data to SciCrunch®, however this is not currently a free service.