GSK-3β promotes cell survival by modulating Bif-1-dependent autophagy and cell death

Department of Urology, The University of Kansas Medical Center, Kansas City, Kansas 66160, USA.
Journal of Cell Science (Impact Factor: 5.43). 02/2010; 123(Pt 6):861-70. DOI: 10.1242/jcs.060475
Source: PubMed


Glycogen synthase kinase 3 beta (GSK-3beta) is constantly active in cells and its activity increases after serum deprivation, indicating that GSK-3beta might play a major role in cell survival under serum starvation. In this study, we attempted to determine how GSK-3beta promotes cell survival after serum depletion. Under full culture conditions (10% FBS), GSK-3beta inhibition with chemical inhibitors or siRNAs failed to induce cell death in human prostate cancer cells. By contrast, under conditions of serum starvation, a profound necrotic cell death was observed as evidenced by cellular morphologic features and biochemical markers. Further analysis revealed that GSK-3beta-inhibition-induced cell death was in parallel with an extensive autophagic response. Interestingly, blocking the autophagic response switched GSK-3beta-inhibition-induced necrosis to apoptotic cell death. Finally, GSK-3beta inhibition resulted in a remarkable elevation of Bif-1 protein levels, and silencing Bif-1 expression abrogated GSK-3beta-inhibition-induced autophagic response and cell death. Taken together, our study suggests that GSK-3beta promotes cell survival by modulating Bif-1-dependent autophagic response and cell death.

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Available from: Benyi Li, Aug 12, 2015
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    • "The large vacuoles indicate the product of fusions among macroautophagic complex and endosomal components. Although the roles of autophagy and large vacuoles in the enterocytes of metamorphic insects have been previously described [30], it remains unclear whether the large vacuoles in ds-DvSnf7 enterocytes are equivalent to the previously described degenerative process of the cells. The third phase of pathology progression displayed extensive apical swelling of the cells and massive cell sloughing toward the lumen (Fig. 2 C). "
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    ABSTRACT: The high sensitivity to oral RNA interference (RNAi) of western corn rootworm (WCR, Diabrotica virgifera virgifera Le Conte) provides a novel tool for pest control. Previous studies have shown that RNAi of DvSnf7, an essential cellular component of endosomal sorting complex required for transport (ESCRT), caused deficiencies in protein de-ubiquitination and autophagy, leading to WCR death. Here we investigated the detailed mechanism leading to larval death by analyzing the ultrastructural changes in midgut enterocytes of WCR treated with double-stranded RNA (ds-DvSnf7). The progressive phases of pathological symptoms caused by DvSnf7-RNAi in enterocytes include: 1) the appearance of irregularly shaped macroautophagic complexes consisting of relatively large lysosomes and multi-lamellar bodies, indicative of failure in autolysosome formation; 2) cell sloughing and loss of apical microvilli, and eventually, 3) massive loss of cellular contents indicating loss of membrane integrity. These data suggest that the critical functions of Snf7 in insect midgut cells demonstrated by the ultrastructural changes in DvSnf7 larval enterocytes underlies the conserved essential function of the ESCRT pathway in autophagy and membrane stability in other organisms.
    PLoS ONE 01/2014; 9(1):e83985. DOI:10.1371/journal.pone.0083985 · 3.23 Impact Factor
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    • "The results obtained with dasatinib in combination with chemotherapy strongly encourage the exploration of dasatinib in combination with doxorubicin in patients with chondrosarcoma. Both the PI3K/AKT/GSK3b and Src kinase pathways are activated by RTKs (Goode et al, 1992; Wheeler et al, 2009), and have diverse roles in promoting growth, survival and metastasis (Aligayer et al, 2002; Wheeler et al, 2009; Yang et al, 2010; McNamara and Degterev, 2011; Saini et al, 2011). We show here that constitutive activation of AKT due to mutations does not have a role in chondrosarcoma, and further research should elucidate which RTK is responsible for the high AKT, GSK3b and Src phosphorylation (Schrage et al, 2009). "
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    ABSTRACT: Background: Chondrosarcomas are malignant cartilage-forming tumours of bone. Because of their resistance to conventional chemotherapy and radiotherapy, currently no treatment strategies exist for unresectable and metastatic chondrosarcoma. Previously, PI3K/AKT/GSK3β and Src kinase pathways were shown to be activated in chondrosarcoma cell lines. Our aim was to investigate the role of these kinases in chemoresistance and migration in chondrosarcoma in relation to TP53 mutation status. Methods: We used five conventional and three dedifferentiated chondrosarcoma cell lines and investigated the effect of PI3K/AKT/GSK3β pathway inhibition (enzastaurin) and Src pathway inhibition (dasatinib) in chemoresistance using WST assay and live cell imaging with AnnexinV staining. Immunohistochemistry on tissue microarrays (TMAs) containing 157 cartilaginous tumours was performed for Src family members. Migration assays were performed with the RTCA xCelligence System. Results: Src inhibition was found to overcome chemoresistance, to induce apoptosis and to inhibit migration. Cell lines with TP53 mutations responded better to combination therapy than wild-type cell lines (P=0.002). Tissue microarray immunohistochemistry confirmed active Src (pSrc) signalling, with Fyn being most abundantly expressed (76.1%). Conclusion: These results strongly indicate Src family kinases, in particular Fyn, as a potential target for the treatment of inoperable and metastatic chondrosarcomas, and to sensitise for doxorubicin especially in the presence of TP53 mutations.
    British Journal of Cancer 08/2013; 109(5). DOI:10.1038/bjc.2013.451 · 4.84 Impact Factor
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    • "Inhibition of GSK3β had been proven to be another factor by which ANE efficiently enhanced pyknotic necrosis under serum-free conditions. It has been reported that GSK3β inactivation could determine the cell fate of either apoptosis or necrosis depending on whether autophagy is present [23]. Since several studies have demonstrated that autophagy could enhance necrosis and ANE caused autophagy through ROS in oral cells, it is plausible that ANE may induce necrosis via enhancing autophagy [6], [24]. "
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    ABSTRACT: Areca nut has been proven to be correlated with various pathologic alterations in oral cavity. However, the mechanisms for such cytopathic effects are still elusive due mostly to the limitations of cell culture systems. Here we discovered that areca nut extract (ANE) induced production of autophagosome vacuoles in cells cultured with rich medium but induced pyknosis and ballooning, two morphological alterations frequently observed in betel quid chewers, in cells under a serum-free culture condition. Permeability of the serum-starved cells to propidium iodide (PI) confirmed ANE induced novel necrosis with pyknosis (pyknotic necrosis), providing a possible explanation for inflammatory infiltration in chewers' mucosa. In these serum-starved cells, ANE strongly induced reactive oxygen species (ROS), which acted as a key switch for the initiation of pyknotic necrosis. Calcium flux was also involved in the morphological alterations. Besides, inhibition of GSK3β by SB216763 significantly exacerbated the pyknotic necrosis either induced by ANE or H2O2 in serum-starved cells, suggesting that GSK3β is a critical regulator for ANE/ROS-mediated pyknotic necrosis. Interestingly, LC3-II transition and PARP cleavage were still detected in the serum-starved cells after ANE treatment, suggesting concurrent activation of apoptotic and autophagic pathways. Finally, insulin could counteract the effect of ANE-induced pyknotic necrosis. Taken together, these data provide a platform for studying ANE-induced cytopathogenesis and the first clinical implication for several pathological alterations, such as ballooning and inflammatory infiltration, in betel quid chewers.
    PLoS ONE 05/2013; 8(5):e63295. DOI:10.1371/journal.pone.0063295 · 3.23 Impact Factor
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