Spy1 Enhances Phosphorylation and Degradation of the Cell Cycle Inhibitor p27

McAndrew, Christopher W.; Gastwirt, Randy F.; Meyer, April N.; Porter, Lisa A.; Donoghue, Daniel J.

doi:10.4161/cc.6.15.4520

Cited by 32 publications

(31 citation statements)

References 64 publications

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“…Spry1 has also been found to prevent inhibition of Cdks by Cdk inhibitors such as p21. By avoiding DNA damage-induced apoptosis and the cell cycle checkpoint, Spry1 can function as an oncoprotein, and indeed its over-expression has been demonstrated to be correlated with breast cancer[23],[24]. Spry1 also plays an important role in cardiac disease models.…”

Section: Mir-21 Targetsmentioning

confidence: 99%

Apoptosis and the target genes of microRNA-21

Buscaglia¹,

Yong²

2011

Chin J Cancer

223

182

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MicroRNA-21 (miR-21) is frequently up-regulated in cancer and the majority of its reported targets are tumor suppressors. Through functional suppression, miR-21 is implicated in practically every walk of oncogenic life: the promotion of cell proliferation, invasion and metastasis, genome instability and mutation, inflammation, replicative immortalization, abnormal metabolism, angiogenesis, and evading apoptosis, immune destruction, and growth suppressors. In particular, miR-21 is strongly involved in apoptosis. In this article, we reviewed the experimentally validated targets of miR-21 and found that two thirds are linked to intrinsic and/or extrinsic pathways of cellular apoptosis. This suggests that miR-21 is an Oncogene which plays a key role in resisting programmed cell death in cancer cells and that targeting apoptosis is a viable therapeutic option against cancers expressing miR-21.

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Section: Mir-21 Targetsmentioning

confidence: 99%

Apoptosis and the target genes of microRNA-21

Buscaglia¹,

Yong²

2011

Chin J Cancer

223

182

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“…It has been well established that the p27 protein level oscillates during transition between cell cycle phases (33,34) and it has been found in several cell lines that the p27 protein is degraded in G 1 and G 1 /S phases (35)(36)(37)(38)(39)(40)(41). We sought to determine whether Fru-2,6-BP levels inversely correlate with p27 protein levels given that ectopic expression of PFKFB3 decreases p27.…”

Section: Ectopic Expression Of Wt Pfkfb3 Increases Phosphorylation Ofmentioning

confidence: 99%

Nuclear Targeting of 6-Phosphofructo-2-kinase (PFKFB3) Increases Proliferation via Cyclin-dependent Kinases

Yalçin

Clem

Simmons

et al. 2009

Journal of Biological Chemistry

199

175

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The regulation of metabolism and growth must be tightly coupled to guarantee the efficient use of energy and anabolic substrates throughout the cell cycle. Fructose 2,6-bisphosphate (Fru-2,6-BP) is an allosteric activator of 6-phosphofructo-1-kinase (PFK-1), a rate-limiting enzyme and essential control point in glycolysis. The concentration of Fru-2,6-BP in mammalian cells is set by four 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatases (PFKFB1-4), which interconvert fructose 6-phosphate and Fru-2,6-BP. The relative functions of the PFKFB3 and PFKFB4 enzymes are of particular interest because they are activated in human cancers and increased by mitogens and low oxygen. We examined the cellular localization of PFKFB3 and PFKFB4 and unexpectedly found that whereas PFKFB4 localized to the cytoplasm (i.e. the site of glycolysis), PFKFB3 localized to the nucleus. We then overexpressed PFKFB3 and observed no change in glucose metabolism but rather a marked increase in cell proliferation. These effects on proliferation were completely abrogated by mutating either the active site or nuclear localization residues of PFKFB3, demonstrating a requirement for nuclear delivery of Fru-2,6-BP. Using protein array analyses, we then found that ectopic expression of PFKFB3 increased the expression of several key cell cycle proteins, including cyclin-dependent kinase (Cdk)-1, Cdc25C, and cyclin D3 and decreased the expression of the cell cycle inhibitor p27, a universal inhibitor of Cdk-1 and the cell cycle. We also observed that the addition of Fru-2,6-BP to HeLa cell lysates increased the phosphorylation of the Cdk-specific Thr-187 site of p27. Taken together, these observations demonstrate an unexpected role for PFKFB3 in nuclear signaling and indicate that Fru-2,6-BP may couple the activation of glucose metabolism with cell proliferation.Neoplastic transformation and growth require a massive increase in glucose uptake and glycolytic flux not only for energy production but also for the synthesis of nucleic acids, amino acids, and fatty acids. A central control point of glycolysis is the negative allosteric regulation of a rate-limiting enzyme, phosphofructokinase-1 (PFK-1), 2 by ATP (i.e. the Pasteur effect) (1, 2). When intracellular ATP production exceeds usage, ATP inhibits PFK-1 and glycolytic flux. Fructose 2,6-bisphosphate (Fru-2,6-BP) is a potent allosteric activator of PFK-1 that overrides this inhibitory influence of ATP on PFK-1, allowing forward flux of the entire pathway (3-5).The steady-state cellular concentration of Fru-2,6-BP is dependent on the activities of bifunctional 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatases (PFKFB), which are encoded by four independent genes (PFKFB1-4) (6, 7). The PFKFB3 mRNA is distinguished by the presence of multiple copies of an AUUUA instability motif in its 3Ј-untranslated region and the PFKFB3 protein product has a high kinase:phosphatase activity ratio (740:1) (8). PFKFB3 mRNA is overexpressed by rapidly proliferating transformed cells and the PFKFB3 protein is high...

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“…Previously, it was determined that truncation of Spy1 at aa 215 retained the ability to bind p27, while truncation at aa 160 in Spy1 disrupted binding to p27 15 ( Fig. 1A; indicated beneath panel).…”

Section: Resultsmentioning

confidence: 88%

“…12 Unlike any known cyclin proteins, Spy1 has also been shown to directly bind to the CKI p27, ultimately leading to ubiquitin-mediated degradation of the CKI. 15 Spy1-p27 and Cdk2 can immunoprecipitate together, supporting the rationale that they can form a trimeric complex, however Spy1 can also interact with each protein directly in vitro. 11,16 Data suggest that in a trimeric complex Spy1 preferentially binds p27 to prevent its inhibitory interactions with Cdk2, and that Cdk2 binding to Spy1 stabilizes this interaction and aids in the phosphorylation of p27 on T187, leading to p27 degradation.…”

Section: Introductionmentioning

confidence: 72%

“…This was not surprising given the large size of the deletion within DMG, as well as the previous results suggesting the essentiality of this region for binding. 15 Although p27 interacts in different ways with known partners, it was previously determined that p27 binding interactions favor positively charged amino acids on the binding partner. [21][22][23] Alignment of the potential p27-binding region within Spy1 from a number of different organisms noted a region of high similarity containing a string of 4 highly conserved positive amino acids (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Direct interactions with both p27 and Cdk2 regulate Spy1-mediated proliferationin vivoandin vitro

et al. 2016

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Families of cyclin-like proteins have emerged that bind and activate cyclin dependent kinases (Cdk)s, directing the phosphorylation of noncanonical Cdk substrates. One of these proteins, Spy1, has demonstrated the unique ability to directly bind and activate both Cdk1 and Cdk2, as well as binding and promoting the degradation of at least one Cdk inhibitor, p27 Kip1 . Spy1 accelerates somatic cell growth and proliferation and is implicated in a number of human cancers including the breast, brain and liver. Herein we isolate key residues mediating the direct interaction with p27. We use mutants of Spy1 to determine the physiological role of direct interactions with distinct binding partners Cdk2 and p27. We demonstrate that disrupting the direct interaction with either Spy1 binding partner decreased endogenous activity of Cdk2, as well as Spy1-mediated proliferation. However, only the direct interaction with p27 was essential for Spy1-mediated effects on p27 stability. In vivo neither mutation completely prevented tumorigenesis, although each mutation slowed the rate of Spy1-mediated tumorigenesis and decreased overall tumor volumes. This work supports the conclusion that direct interaction with both p27 and Cdk2 contribute to Spy1-mediated effects on cell growth. It is important to elucidate the dynamics of these interactions and to consider these data when assessing functional outcomes.

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Spy1 Enhances Phosphorylation and Degradation of the Cell Cycle Inhibitor p27

Cited by 32 publications

References 64 publications

Apoptosis and the target genes of microRNA-21

Apoptosis and the target genes of microRNA-21

Nuclear Targeting of 6-Phosphofructo-2-kinase (PFKFB3) Increases Proliferation via Cyclin-dependent Kinases

Direct interactions with both p27 and Cdk2 regulate Spy1-mediated proliferationin vivoandin vitro

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