GSK-3 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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    • "AKT has been shown to phosphorylate and inactivate GSK3, which is a key regulator of differentiation, metabolism, apoptosis, autophagy, as well as tumorigenesis [9] [10] [11] [12] [13] [14] [15] [16]. Two functional isoforms of GSK3 known as GSK3α and GSK3β are produced from separate genes, but share 97% amino acid homology [9] [10] [11]. "
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    ABSTRACT: Background: Acute myeloid leukemia (AML) patients with highly active AKT tend to do poorly. Cell cycle arrest and apoptosis are tightly regulated by AKT via phosphorylation of GSK3α and β isoforms which inactivates these kinases. In the current study we examine the prognostic role of AKT mediated GSK3 phosphorylation in AML. Methods: We analyzed GSK3α/β phosphorylation by reverse phase protein analysis (RPPA) in a cohort of 511 acute myeloid leukemia (AML) patients. Levels of phosphorylated GSK3 were correlated with patient characteristics including survival and with expression of other proteins important in AML cell survival. Results: High levels of p-GSK3α/β correlated with adverse overall survival and a lower incidence of complete remission duration in patients with intermediate cytogenetics, but not in those with unfavorable cytogenetics. Intermediate cytogenetic patients with FLT3 mutation also fared better respectively when p-GSK3α/β levels were lower. Phosphorylated GSK3α/β expression was compared and contrasted with that of 229 related cell cycle arrest and/or apoptosis proteins. Consistent with p-GSK3α/β as an indicator of AKT activation, RPPA revealed that p-GSK3α/β positively correlated with phosphorylation of AKT, BAD, and P70S6K, and negatively correlated with β-catenin and FOXO3A. PKCδ also positively correlated with p-GSK3α/β expression, suggesting crosstalk between the AKT and PKC signaling pathways in AML cells. Conclusions: These findings suggest that AKT-mediated phosphorylation of GSK3α/β may be beneficial to AML cell survival, and hence detrimental to the overall survival of AML patients. Intrinsically, p-GSK3α/β may serve as an important adverse prognostic factor for a subset of AML patients.
    Full-text · Article · Jul 2015 · Biochimica et Biophysica Acta - Clinical
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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.
    Full-text · Article · Jan 2014 · PLoS ONE
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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.
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