Fe65, a Ligand of the Alzheimer's β-Amyloid Precursor Protein, Blocks Cell Cycle Progression by Down-regulating Thymidylate Synthase Expression

Bruni, Paola; Minopoli, Giuseppina; Brancaccio, Tiziana; Napolitano, Maria; Faraonio, Raffaella; Zambrano, Nicola; Hansen, Ulla; Russo, Tommaso

doi:10.1074/jbc.m205227200

Cited by 74 publications

(56 citation statements)

References 32 publications

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“…LSF, a member of a small family of transcription factors conserved throughout the animal kingdom (11), is ubiquitously expressed in mammalian tissues and cell lines (12). LSF activity is tightly controlled as cells progress from quiescence into DNA replication (G0 to S) (13,14), and is required for efficient progression of cells through the G1/S transition (15,16). Regulation of LSF activity normally occurs via posttranslational modifications, with LSF protein levels generally being low and constant.…”

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confidence: 99%

Antiproliferative small-molecule inhibitors of transcription factor LSF reveal oncogene addiction to LSF in hepatocellular carcinoma

Grant¹,

Bishop

Christadore

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide. Despite the prevalence of HCC, there is no effective, systemic treatment. The transcription factor LSF is a promising protein target for chemotherapy; it is highly expressed in HCC patient samples and cell lines, and promotes oncogenesis in rodent xenograft models of HCC. Here, we identify small molecules that effectively inhibit LSF cellular activity. The lead compound, factor quinolinone inhibitor 1 (FQI1), inhibits LSF DNA-binding activity both in vitro, as determined by electrophoretic mobility shift assays, and in cells, as determined by ChIP. Consistent with such inhibition, FQI1 eliminates transcriptional stimulation of LSF-dependent reporter constructs. FQI1 also exhibits antiproliferative activity in multiple cell lines. In LSF-overexpressing cells, including HCC cells, cell death is rapidly induced; however, primary or immortalized hepatocytes are unaffected by treatment with FQI1. The highly concordant structure–activity relationship of a panel of 23 quinolinones strongly suggests that the growth inhibitory activity is due to a single biological target or family. Coupled with the striking agreement between the concentrations required for antiproliferative activity (GI 50 s) and for inhibition of LSF transactivation (IC 50 s), we conclude that LSF is the specific biological target of FQIs. Based on these in vitro results, we tested the efficacy of FQI1 in inhibiting HCC tumor growth in a mouse xenograft model. As a single agent, tumor growth was dramatically inhibited with no observable general tissue cytotoxicity. These findings support the further development of LSF inhibitors for cancer chemotherapy.

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confidence: 99%

Antiproliferative small-molecule inhibitors of transcription factor LSF reveal oncogene addiction to LSF in hepatocellular carcinoma

Grant¹,

Bishop

Christadore

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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“…FE65 is able to translocate between the nucleus and cytoplasm, consistent with the distinct locations of its multiple binding partners. Through these protein-protein interactions, FE65 may impact upon APP processing (9 -12), gene expression (13,14), pre-mRNA splicing (15), cell cycle progression (16), plasma membrane dynamics (17,18), axonal projection and neuronal positioning (19), and learning and memory (8).…”

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Endoproteolytic Cleavage of FE65 Converts the Adaptor Protein to a Potent Suppressor of the sAPPα Pathway in Primates

Wang

Yang

et al. 2005

Journal of Biological Chemistry

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Adaptor protein FE65 (APBB1) specifically binds to the intracellular tail of the type I transmembrane protein, ␤-amyloid precursor protein (APP). The formation of this complex may be important for modulation of the processing and function of APP. APP is proteolytically cleaved at multiple sites. The cleavages and their regulation are of central importance in the pathogenesis of dementias of the Alzheimer type. In cell cultures and perhaps in vivo, secretion of the ␣-cleaved APP ectodomain (sAPP␣) is the major pathway in the most cells. Regulation of the process may require extracellular/intracellular cues. Neither extracellular ligands nor intracellular mediators have been identified, however. Here, we show novel evidence that the major isoform of FE65 (97-kDa FE65, p97FE65) can be converted to a 65-kDa N-terminally truncated C-terminal fragment (p65FE65) via endoproteolysis. The cleavage region locates immediately after an acidic residue cluster but before the three major protein-protein binding domains. The cleavage activity is particularly high in human and non-human primate cells and low in rodent cells; the activity appears to be triggered/enhanced by high cell density, presumably via cell-cell/cell-substrate contact cues. As a result, p65FE65 exhibits extraordinarily high affinity for APP (up to 40-fold higher than p97FE65) and potent suppression (up to 90%) of secretion of sAPP␣. Strong p65FE65-APP binding is required for the suppression. The results suggest that p65FE65 may be an intracellular mediator in a signaling cascade regulating ␣-secretion of APP, particularly in primates.FE65 is a multimodular adaptor protein, consisting of three major protein-protein interaction domains, a WW domain and two phosphotyrosine interaction domains (PID) 1 (1, 2) ( Fig. 2A). The interaction between FE65 and APP mainly takes place between the C-terminal PID (PID2) and the APP intracellular domain (AICD), although other regions may also potentially contribute to the action. The physiological effects of FE65-〈PP complexes are not well understood. Genetic evidence suggests that strong FE65-〈PP binding was favored by natural selection during animal evolution toward human lineage (3). 〈PP is a widely studied protein because of its role in the pathogenesis of dementias of the Alzheimer type (DAT). FE65 is predominantly expressed in central nervous system neurons, and its expression is regulated during development and aging, with high levels corresponding to the timing of neural tissue formation and high neuronal activity (4 -8). Selective knockout of the p97FE65 isoform results in modest impairments in learning but severe deficits in relearning spatial tasks (8). These phenotypes reflect reduced synaptic plasticity. Thus, the APP-FE65 pathway may play roles in normal and abnormal cognitive functions. In addition to binding to AICD, FE65 can also interact, at least in vitro, with several other proteins through its WW and PID1 domains (1, 2). FE65 is able to translocate between the nucleus and cytoplasm, consistent with the d...

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“…The transcription factor LSF is required for cell cycle progression from quiescence into S phase (11,31). Previous studies regarding regulation of LSF following mitogenic stimulation of cells identified multiple MAPK signal transduction (30,47,49,52).…”

Section: Discussionmentioning

confidence: 99%

Phosphorylation by Cyclin C/Cyclin-Dependent Kinase 2 following Mitogenic Stimulation of Murine Fibroblasts Inhibits Transcriptional Activity of LSF during G₁ Progression

Saxena

Powell

Fecko

et al. 2009

Molecular and Cellular Biology

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Transcription factor LSF is required for progression from quiescence through the cell cycle, regulating thymidylate synthase (Tyms) expression at the G 1 /S boundary. Given the constant level of LSF protein from G 0 through S, we investigated whether LSF is regulated by phosphorylation in G 1 . In vitro, LSF is phosphorylated by cyclin E/cyclin-dependent kinase 2 (CDK2), cyclin C/CDK2, and cyclin C/CDK3, predominantly on S309. Phosphorylation of LSF on S309 is maximal 1 to 2 h after mitogenic stimulation of quiescent mouse fibroblasts. This phosphorylation is mediated by cyclin C-dependent kinases, as shown by coimmunoprecipitation of LSF and cyclin C in early G 1 and by abrogation of LSF S309 phosphorylation upon suppression of cyclin C with short interfering RNA. Although mouse fibroblasts lack functional CDK3 (the partner of cyclin C in early G 1 in human cells), CDK2 compensates for this absence. By transient transfection assays, phosphorylation at S309, mediated by cyclin C overexpression, inhibits LSF transactivation. Moreover, overexpression of cyclin C and CDK3 inhibits induction of endogenous Tyms expression at the G 1 /S transition. These results identify LSF as only the second known target (in addition to pRb) of cyclin C/CDK activity during progression from quiescence to early G 1 . Unexpectedly, this phosphorylation prevents induction of LSF target genes until late G 1 .The transcription factor LSF (late simian virus 40 factor [20], also named CP2 [24], LBP-1c [53], and SEF [6]) is ubiquitously expressed in all cell types (32, 44). LSF is essential for cell cycle progression at the G 1 /S transition after reentry of quiescent cells into the cell cycle, substantially through its regulation of thymidylate synthase (Tyms) gene expression (31). Disruption of LSF function can lead either to apoptosis in S phase (31) or to cell cycle arrest at the G 1 /S transition (11), both phenotypes being relieved by a source of exogenous thymidine, thereby circumventing the requirement for thymidylate synthase activity.In investigating how LSF activity could be modulated during cell cycle progression, we previously demonstrated that LSF is targeted by the MEK/extracellular signal-regulated kinase (ERK) signaling pathway, which is critical for reentry of quiescent cells into the G 1 phase of the cell cycle (35). ERK phosphorylates LSF at S291 upon mitogenic stimulation of multiple cell types, including mouse fibroblasts and primary peripheral human T lymphocytes (30, 49). Signaling pathways essential for the subsequent progression through G 1 into S phase include the G 1 cyclin-dependent kinases (CDKs) (38). These include the extensively investigated D-type cyclins and their associated kinases CDK4/6 as well as E-type cyclins associated with CDK2 (39, 41). Recently, an additional cyclin/ CDK complex, cyclin C/CDK3, was also shown to facilitate efficient exit of human cells from G 0 into the cell cycle (33, 36). Cyclin C was not previously thought to be a regulator of cell cycle progression but was instead demonstrated...

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Fe65, a Ligand of the Alzheimer's β-Amyloid Precursor Protein, Blocks Cell Cycle Progression by Down-regulating Thymidylate Synthase Expression

Cited by 74 publications

References 32 publications

Antiproliferative small-molecule inhibitors of transcription factor LSF reveal oncogene addiction to LSF in hepatocellular carcinoma

Antiproliferative small-molecule inhibitors of transcription factor LSF reveal oncogene addiction to LSF in hepatocellular carcinoma

Endoproteolytic Cleavage of FE65 Converts the Adaptor Protein to a Potent Suppressor of the sAPPα Pathway in Primates

Phosphorylation by Cyclin C/Cyclin-Dependent Kinase 2 following Mitogenic Stimulation of Murine Fibroblasts Inhibits Transcriptional Activity of LSF during G₁ Progression

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Fe65, a Ligand of the Alzheimer's β-Amyloid Precursor Protein, Blocks Cell Cycle Progression by Down-regulating Thymidylate Synthase Expression

Cited by 74 publications

References 32 publications

Antiproliferative small-molecule inhibitors of transcription factor LSF reveal oncogene addiction to LSF in hepatocellular carcinoma

Antiproliferative small-molecule inhibitors of transcription factor LSF reveal oncogene addiction to LSF in hepatocellular carcinoma

Endoproteolytic Cleavage of FE65 Converts the Adaptor Protein to a Potent Suppressor of the sAPPα Pathway in Primates

Phosphorylation by Cyclin C/Cyclin-Dependent Kinase 2 following Mitogenic Stimulation of Murine Fibroblasts Inhibits Transcriptional Activity of LSF during G1 Progression

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Phosphorylation by Cyclin C/Cyclin-Dependent Kinase 2 following Mitogenic Stimulation of Murine Fibroblasts Inhibits Transcriptional Activity of LSF during G₁ Progression