Degradation of Mcl-1 by β-TrCP Mediates Glycogen Synthase Kinase 3-Induced Tumor Suppression and Chemosensitization

ABSTRACT Apoptosis is critical for embryonic development, tissue homeostasis, and tumorigenesis and is determined largely by the Bcl-2 family of antiapoptotic and prosurvival regulators. Here, we report that glycogen synthase kinase 3 (GSK-3) was required for Mcl-1 degradation, and we identified a novel mechanism for proteasome-mediated Mcl-1 turnover in which GSK-3β associates with and phosphorylates Mcl-1 at one consensus motif (155 STDG159 SLPS163 T; phosphorylation sites are in italics), which will lead to the association of Mcl-1 with the E3 ligase β-TrCP, and β-TrCP then facilitates the ubiquitination and degradation of phosphorylated Mcl-1. A variant of Mcl-1 (Mcl-1-3A), which abolishes the phosphorylations by GSK-3β and then cannot be ubiquitinated by β-TrCP, is much more stable than wild-type Mcl-1 and able to block the proapoptotic function of GSK-3β and enhance chemoresistance. Our results indicate that the turnover of Mcl-1 by β-TrCP is an essential mechanism for GSK-3β-induced apoptosis and contributes to GSK-3β-mediated tumor suppression and chemosensitization.

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GSK-3β in Pancreatic Cancer: Spotlight on 9-ING-41, Its Therapeutic Potential and Immune Modulatory Properties

Biology ◽

10.3390/biology10070610 ◽

2021 ◽

Vol 10 (7) ◽

pp. 610

Author(s):

Robin Park ◽

Andrew L. Coveler ◽

Ludimila Cavalcante ◽

Anwaar Saeed

Keyword(s):

Pancreatic Cancer ◽

Therapeutic Potential ◽

Glycogen Synthase ◽

Glycogen Synthase Kinase ◽

Glycogen Synthase Kinase 3 ◽

In Vivo Models ◽

Gsk 3Β ◽

Early Phase Clinical Trials

Glycogen synthase kinase-3 beta is a ubiquitously and constitutively expressed molecule with pleiotropic function. It acts as a protooncogene in the development of several solid tumors including pancreatic cancer through its involvement in various cellular processes including cell proliferation, survival, invasion and metastasis, as well as autophagy. Furthermore, the level of aberrant glycogen synthase kinase-3 beta expression in the nucleus is inversely correlated with tumor differentiation and survival in both in vitro and in vivo models of pancreatic cancer. Small molecule inhibitors of glycogen synthase kinase-3 beta have demonstrated therapeutic potential in pre-clinical models and are currently being evaluated in early phase clinical trials involving pancreatic cancer patients with interim results showing favorable results. Moreover, recent studies support a rationale for the combination of glycogen synthase kinase-3 beta inhibitors with chemotherapy and immunotherapy, warranting the evaluation of novel combination regimens in the future.

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Glycogen synthase kinase-3 inhibition sensitizes human induced pluripotent stem cells to thiol-containing antioxidants induced apoptosis

Stem Cell Research ◽

10.1016/j.scr.2017.07.019 ◽

2017 ◽

Vol 23 ◽

pp. 182-187 ◽

Cited By ~ 4

Author(s):

Chengyi Tu ◽

Robert Xu ◽

Meghana Koleti ◽

Janet Zoldan

Keyword(s):

Stem Cells ◽

Induced Pluripotent Stem Cells ◽

Pluripotent Stem Cells ◽

Glycogen Synthase ◽

Glycogen Synthase Kinase ◽

Glycogen Synthase Kinase 3 ◽

Induced Pluripotent ◽

Induced Apoptosis

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Deletion of Cardiomyocyte Glycogen Synthase Kinase-3 Beta (GSK-3β) Improves Systemic Glucose Tolerance with Maintained Heart Function in Established Obesity

Cells ◽

10.3390/cells9051120 ◽

2020 ◽

Vol 9 (5) ◽

pp. 1120 ◽

Cited By ~ 1

Author(s):

Manisha Gupte ◽

Prachi Umbarkar ◽

Anand Prakash Singh ◽

Qinkun Zhang ◽

Sultan Tousif ◽

...

Keyword(s):

Glucose Tolerance ◽

Cardiac Function ◽

Cardiac Dysfunction ◽

Glycogen Synthase ◽

Critical Role ◽

Glycogen Synthase Kinase ◽

Glycogen Synthase Kinase 3 ◽

Total Period ◽

Gsk 3Β

Obesity is an independent risk factor for cardiovascular diseases (CVD), including heart failure. Thus, there is an urgent need to understand the molecular mechanism of obesity-associated cardiac dysfunction. We recently reported the critical role of cardiomyocyte (CM) Glycogen Synthase Kinase-3 beta (GSK-3β) in cardiac dysfunction associated with a developing obesity model (deletion of CM-GSK-3β prior to obesity). In the present study, we investigated the role of CM-GSK-3β in a clinically more relevant model of established obesity (deletion of CM-GSK-3β after established obesity). CM-GSK-3β knockout (GSK-3βfl/flCre+/−) and controls (GSK-3βfl/flCre−/−) mice were subjected to a high-fat diet (HFD) in order to establish obesity. After 12 weeks of HFD treatment, all mice received tamoxifen injections for five consecutive days to delete GSK-3β specifically in CMs and continued on the HFD for a total period of 55 weeks. To our complete surprise, CM-GSK-3β knockout (KO) animals exhibited a globally improved glucose tolerance and maintained normal cardiac function. Mechanistically, in stark contrast to the developing obesity model, deleting CM-GSK-3β in obese animals did not adversely affect the GSK-3αS21 phosphorylation (activity) and maintained canonical β-catenin degradation pathway and cardiac function. As several GSK-3 inhibitors are in the trial to treat various chronic conditions, including metabolic diseases, these findings have important clinical implications. Specifically, our results provide critical pre-clinical data regarding the safety of GSK-3 inhibition in obese patients.

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Glycogen Synthase Kinase 3 Phosphorylates Hypoxia-Inducible Factor 1α and Mediates Its Destabilization in a VHL-Independent Manner

Molecular and Cellular Biology ◽

10.1128/mcb.00015-07 ◽

2007 ◽

Vol 27 (9) ◽

pp. 3253-3265 ◽

Cited By ~ 134

Author(s):

Daniela Flügel ◽

Agnes Görlach ◽

Carine Michiels ◽

Thomas Kietzmann

Keyword(s):

Protein Kinase ◽

Metabolic Diseases ◽

Glycogen Synthase ◽

Protein Kinase B ◽

Hypoxia Inducible Factor ◽

Glycogen Synthase Kinase ◽

Glycogen Synthase Kinase 3 ◽

Independent Manner ◽

Von Hippel Lindau ◽

Gsk 3Β

ABSTRACT Hypoxia-inducible transcription factor 1α (HIF-1α) is a key player in the response to hypoxia. Additionally, HIF-1α responds to growth factors and hormones which can act via protein kinase B (Akt). However, HIF-1α is not a direct substrate for this kinase. Therefore, we investigated whether the protein kinase B target glycogen synthase kinase 3 (GSK-3) may have an impact on HIF-1α. We found that the inhibition or depletion of GSK-3 induced HIF-1α whereas the overexpression of GSK-3β reduced HIF-1α. These effects were mediated via three amino acid residues in the oxygen-dependent degradation domain of HIF-1α. In addition, mutation analyses and experiments with von Hippel-Lindau (VHL)-defective cells indicated that GSK-3 mediates HIF-1α degradation in a VHL-independent manner. In line with these observations, the inhibition of the proteasome reversed the GSK-3 effects, indicating that GSK-3 may target HIF-1α to the proteasome by phosphorylation. Thus, the direct regulation of HIF-1α stability by GSK-3 may influence physiological processes or pathophysiological situations such as metabolic diseases or tumors.

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