Protein Kinase SGK Mediates Survival Signals by Phosphorylating the Forkhead Transcription Factor FKHRL1 (FOXO3a)

ABSTRACT Serum- and glucocorticoid-inducible kinases (SGKs) form a novel family of serine/threonine kinases that are activated in response to a variety of extracellular stimuli. SGKs are related to Akt (also called PKB), a serine/threonine kinase that plays a crucial role in promoting cell survival. Like Akt, SGKs are activated by the phosphoinositide-3 kinase (PI3K) and translocate to the nucleus upon growth factor stimulation. However the physiological substrates and cellular functions of SGKs remained to be identified. We hypothesized that SGKs regulate cellular functions in concert with Akt by phosphorylating common targets within the nucleus. The best-characterized nuclear substrates of Akt are transcription factors of the Forkhead family. Akt phosphorylates Forkhead transcription factors such as FKHRL1, leading to FKHRL1's exit from the nucleus and the consequent shutoff of FKHRL1 target genes. We show here that SGK1, like Akt, promotes cell survival and that it does so in part by phosphorylating and inactivating FKHRL1. However, SGK and Akt display differences with respect to the efficacy with which they phosphorylate the three regulatory sites on FKHRL1. While both kinases can phosphorylate Thr-32, SGK displays a marked preference for Ser-315 whereas Akt favors Ser-253. These findings suggest that SGK and Akt may coordinately regulate the function of FKHRL1 by phosphorylating this transcription factor at distinct sites. The efficient phosphorylation of these three sites on FKHRL1 by SGK and Akt appears to be critical to the ability of growth factors to suppress FKHRL1-dependent transcription, thereby preventing FKHRL1 from inducing cell cycle arrest and apoptosis. These findings indicate that SGK acts in concert with Akt to propagate the effects of PI3K activation within the nucleus and to mediate the biological outputs of PI3K signaling, including cell survival and cell cycle progression.

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Forkhead Transcription Factor FoxM1 Regulates Mitotic Entry and Prevents Spindle Defects in Cerebellar Granule Neuron Precursors

Molecular and Cellular Biology ◽

10.1128/mcb.00707-07 ◽

2007 ◽

Vol 27 (23) ◽

pp. 8259-8270 ◽

Cited By ~ 61

Author(s):

Ulrich Schüller ◽

Qing Zhao ◽

Susana A. Godinho ◽

Vivi M. Heine ◽

René H. Medema ◽

...

Keyword(s):

Cell Cycle ◽

Transcription Factor ◽

Target Genes ◽

Cyclin B1 ◽

Null Alleles ◽

Cerebellar Granule Neuron ◽

Forkhead Transcription Factor ◽

Cerebellar Granule ◽

Granule Neuron ◽

Granule Neuron Precursors

ABSTRACT The forkhead transcription factor FoxM1 has been reported to regulate, variously, proliferation and/or spindle formation during the G2/M transition of the cell cycle. Here we define specific functions of FoxM1 during brain development by the investigation of FoxM1 loss-of-function mutations in the context of Sonic hedgehog (Shh)-induced neuroproliferation in cerebellar granule neuron precursors (CGNP). We show that FoxM1 is expressed in the cerebellar anlagen as well as in postnatal proliferating CGNP and that it is upregulated in response to activated Shh signaling. To determine the requirements for FoxM1 function, we used transgenic mice carrying conventional null alleles or conditionally targeted alleles in conjunction with specific Cre recombinase expression in CGNP or early neural precursors driven by Math1 or Nestin enhancers. Although the overall cerebellar morphology was grossly normal, we observed that the entry into mitosis was postponed both in vivo and in Shh-treated CGNP cultures. Cell cycle analysis and immunohistochemistry with antibodies against phosphorylated histone H3 indicated a significant delay in the G2/M transition. Consistent with this, FoxM1-deficient CGNP showed decreased levels of the cyclin B1 and Cdc25b proteins. Furthermore, the loss of FoxM1 resulted in spindle defects and centrosome amplification. These findings indicate that the functions of FoxM1 in Shh-induced neuroproliferation are restricted to the regulation of the G2/M transition in CGNP, most probably through transcriptional effects on target genes such as those coding for B-type cyclins.

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Essential Dosage-Dependent Functions of the Transcription Factor Yin Yang 1 in Late Embryonic Development and Cell Cycle Progression

Molecular and Cellular Biology ◽

10.1128/mcb.26.9.3565-3581.2006 ◽

2006 ◽

Vol 26 (9) ◽

pp. 3565-3581 ◽

Cited By ~ 119

Author(s):

El Bachir Affar ◽

Frédérique Gay ◽

Yujiang Shi ◽

Huifei Liu ◽

Maite Huarte ◽

...

Keyword(s):

Cell Cycle ◽

Cell Proliferation ◽

Transcription Factor ◽

Cell Cycle Progression ◽

Target Genes ◽

Eukaryotic Cell ◽

Dependent Manner ◽

Phenotypic Analysis ◽

Yin Yang 1 ◽

Yin Yang

ABSTRACT Constitutive ablation of the Yin Yang 1 (YY1) transcription factor in mice results in peri-implantation lethality. In this study, we used homologous recombination to generate knockout mice carrying yy1 alleles expressing various amounts of YY1. Phenotypic analysis of yy1 mutant embryos expressing ∼75%, ∼50%, and ∼25% of the normal complement of YY1 identified a dosage-dependent requirement for YY1 during late embryogenesis. Indeed, reduction of YY1 levels impairs embryonic growth and viability in a dose-dependent manner. Analysis of the corresponding mouse embryonic fibroblast cells also revealed a tight correlation between YY1 dosage and cell proliferation, with a complete ablation of YY1 inducing cytokinesis failure and cell cycle arrest. Consistently, RNA interference-mediated inhibition of YY1 in HeLa cells prevents cytokinesis, causes proliferative arrest, and increases cellular sensitivity to various apoptotic agents. Genome-wide expression profiling identified a plethora of YY1 target genes that have been implicated in cell growth, proliferation, cytokinesis, apoptosis, development, and differentiation, suggesting that YY1 coordinates multiple essential biological processes through a complex transcriptional network. These data not only shed new light on the molecular basis for YY1 developmental roles and cellular functions, but also provide insight into the general mechanisms controlling eukaryotic cell proliferation, apoptosis, and differentiation.

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Optimal B-cell proliferation requires phosphoinositide 3-kinase–dependent inactivation of FOXO transcription factors

Blood ◽

10.1182/blood-2003-09-3071 ◽

2004 ◽

Vol 104 (3) ◽

pp. 784-787 ◽

Cited By ~ 92

Author(s):

Isharat Yusuf ◽

Xiaocui Zhu ◽

Michael G. Kharas ◽

Jing Chen ◽

David A. Fruman

Keyword(s):

Cell Cycle ◽

Transcription Factors ◽

B Cells ◽

B Cell ◽

Nuclear Export ◽

Cell Cycle Progression ◽

B Lymphocyte ◽

Cell Receptor ◽

Dependent Inactivation ◽

Phosphoinositide 3 Kinase

AbstractTranscription factors of the Forkhead Box, class O (FOXO) family promote cell-cycle arrest and/or apoptosis in a variety of cell types. Mitogenic stimuli inactivate FOXO function by way of an evolutionarily conserved pathway involving the activation of phosphoinositide 3-kinase (PI3K) and its downstream effector, Akt. Although PI3K activation is required for B-lymphocyte proliferation, it is not known whether PI3K-dependent inactivation of FOXO proteins is important for cell-cycle progression and survival of these cells. Here, we show that B-cell receptor (BCR) engagement triggers PI3K-dependent phosphorylation and nuclear export of FOXO1. Furthermore, forced expression of PI3K-independent variants of FOXO1 or FOXO3a in activated B cells induces partial arrest in G1 phase of the cell cycle and increases apoptosis. These findings establish that FOXO inactivation is a functionally important consequence of PI3K signaling in primary B cells.

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VprBP/DCAF1 Regulates the Degradation and Nonproteolytic Activation of the Cell Cycle Transcription Factor FoxM1

Molecular and Cellular Biology ◽

10.1128/mcb.00609-16 ◽

2017 ◽

Vol 37 (13) ◽

Cited By ~ 13

Author(s):

Xianxi Wang ◽

Anthony Arceci ◽

Kelly Bird ◽

Christine A. Mills ◽

Rajarshi Choudhury ◽

...

Keyword(s):

Cell Cycle ◽

Transcription Factor ◽

Cell Cycle Progression ◽

Target Genes ◽

Chromosome Instability ◽

Vital Role ◽

Activation Mechanism ◽

Cycle Progression ◽

Protein Levels ◽

Ubiquitin System

ABSTRACT The oncogenic transcription factor FoxM1 plays a vital role in cell cycle progression, is activated in numerous human malignancies, and is linked to chromosome instability. We characterize here a cullin 4-based E3 ubiquitin ligase and its substrate receptor, VprBP/DCAF1 (CRL4VprBP), which we show regulate FoxM1 ubiquitylation and degradation. Paradoxically, we also found that the substrate receptor VprBP is a potent FoxM1 activator. VprBP depletion reduces expression of FoxM1 target genes and impairs mitotic entry, whereas ectopic VprBP expression strongly activates a FoxM1 transcriptional reporter. VprBP binding to CRL4 is reduced during mitosis, and our data suggest that VprBP activation of FoxM1 is ligase independent. This implies a nonproteolytic activation mechanism that is reminiscent of, yet distinct from, the ubiquitin-dependent transactivation of the oncoprotein Myc by other E3s. Significantly, VprBP protein levels were upregulated in high-grade serous ovarian patient tumors, where the FoxM1 signature is amplified. These data suggest that FoxM1 abundance and activity are controlled by VprBP and highlight the functional repurposing of E3 ligase substrate receptors independent of the ubiquitin system.

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The Oncogenic Function of PLAGL2 is Mediated via Specific Target Genes Through a Wnt-independent Mechanism in Colorectal Cancer

10.1101/2020.10.14.339531 ◽

2020 ◽

Author(s):

Anthony D. Fischer ◽

Daniel A. Veronese-Paniagua ◽

Shriya Swaminathan ◽

Hajime Kashima ◽

Deborah C. Rubin ◽

...

Keyword(s):

Colorectal Cancer ◽

Cell Cycle ◽

Transcription Factor ◽

Stem Cell ◽

Wnt Signaling ◽

Cell Lines ◽

Cell Cycle Progression ◽

Target Genes ◽

Bhlh Transcription Factor ◽

Cycle Progression

ABSTRACTColorectal cancer (CRC) tumorigenesis and progression are linked to common oncogenic mutations, especially in the tumor suppressor APC, whose loss triggers the deregulation of TCF4/β-Catenin activity. CRC tumorigenesis is also driven by multiple epi-mutational modifiers, such as transcriptional regulators. We describe the common (and near-universal) activation of the zinc finger transcription factor and Let-7 target PLAGL2 in CRC and find that it is a key driver of intestinal epithelial transformation. PLAGL2 drives proliferation, cell cycle progression, and anchorage-independent growth in CRC cell lines and non-transformed intestinal cells. Investigating effects of PLAGL2 on downstream pathways revealed very modest effects on canonical Wnt signaling. Alternatively, we find pronounced effects on the direct PLAGL2 target genes IGF2, a fetal growth factor, and ASCL2, an intestinal stem cell-specific bHLH transcription factor. Inactivation of PLAGL2 in CRC cell lines has pronounced effects on ASCL2 reporter activity. Furthermore, ASCL2 expression can partially rescue deficits of proliferation and cell cycle progression caused by depletion of PLAGL2 in CRC cell lines. Thus, the oncogenic effects of PLAGL2 appear to be mediated via core stem cell and onco-fetal pathways, with minimal effects on downstream Wnt signaling.

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Phosphoinositide 3-kinase and Forkhead, a switch for cell division

Biochemical Society Transactions ◽

10.1042/bst0320360 ◽

2004 ◽

Vol 32 (2) ◽

pp. 360-361 ◽

Cited By ~ 24

Author(s):

L. Martínez-Gac ◽

B. Álvarez ◽

Z. García ◽

M. Marqués ◽

M. Arrizabalaga ◽

...

Keyword(s):

Cell Cycle ◽

Transcription Factors ◽

Cell Division ◽

Cell Growth ◽

Cell Cycle Progression ◽

Cycle Progression ◽

Downstream Effector ◽

Cell Cycle Entry ◽

Foxo Transcription Factors ◽

Phosphoinositide 3 Kinase

Cell cycle progression is a tightly controlled process. To initiate cell division, mitogens trigger a number of early signals that promote the G0–G1 transition by inducing cell growth and the activation of G1 cyclins. Activation of cyclin E/cdk2 (cyclin-dependent kinase 2) at the end of G1 is then required to trigger DNA synthesis (S phase entry). Among the early signals induced by mitogens, activation of PI3K (phosphoinositide 3-kinase) appears essential to induce cell cycle entry, as it regulates cell growth signalling pathways, which in turn determine the rate of cell cycle progression. Another mechanisms by which PI3K and its downstream effector protein kinase B regulate cell cycle entry is by inactivation of the FOXO (Forkhead Box, subgroup O) transcription factors, which induce expression of quiescence genes such as those encoding p27kip, p130 and cyclin G2. PI3K/FOXO then work as a complementary switch: when PI3K is active, FOXO transcription factors are inactive. The switch is turned on and off at different phases of the cell cycle, thus regulating cell cycle progression.

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Regulation of cell cycle progression by forkhead transcription factor FOXO3 through its binding partner DNA replication factor Cdt1

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1203210109 ◽

2012 ◽

Vol 109 (15) ◽

pp. 5717-5722 ◽

Cited By ~ 30

Author(s):

Y. Zhang ◽

Y. Xing ◽

L. Zhang ◽

Y. Mei ◽

K. Yamamoto ◽

...

Keyword(s):

Cell Cycle ◽

Transcription Factor ◽

Dna Replication ◽

Cell Cycle Progression ◽

Forkhead Transcription Factor ◽

Cycle Progression ◽

Binding Partner ◽

Replication Factor ◽

Regulation Of Cell Cycle

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Regulatory Network Analysis in Estradiol-Treated Human Endothelial Cells

International Journal of Molecular Sciences ◽

10.3390/ijms22158193 ◽

2021 ◽

Vol 22 (15) ◽

pp. 8193

Author(s):

Daniel Pérez-Cremades ◽

Ana B. Paes ◽

Xavier Vidal-Gómez ◽

Ana Mompeón ◽

Carlos Hermenegildo ◽

...

Keyword(s):

Endothelial Cells ◽

Transcription Factor ◽

Transcription Factors ◽

Regulatory Network ◽

Mirna Target ◽

Target Genes ◽

Functional Characterization ◽

Human Endothelial Cells ◽

Mrna Targets ◽

Canonical Pathways

Background/Aims: Estrogen has been reported to have beneficial effects on vascular biology through direct actions on endothelium. Together with transcription factors, miRNAs are the major drivers of gene expression and signaling networks. The objective of this study was to identify a comprehensive regulatory network (miRNA-transcription factor-downstream genes) that controls the transcriptomic changes observed in endothelial cells exposed to estradiol. Methods: miRNA/mRNA interactions were assembled using our previous microarray data of human umbilical vein endothelial cells (HUVEC) treated with 17β-estradiol (E2) (1 nmol/L, 24 h). miRNA–mRNA pairings and their associated canonical pathways were determined using Ingenuity Pathway Analysis software. Transcription factors were identified among the miRNA-regulated genes. Transcription factor downstream target genes were predicted by consensus transcription factor binding sites in the promoter region of E2-regulated genes by using JASPAR and TRANSFAC tools in Enrichr software. Results: miRNA–target pairings were filtered by using differentially expressed miRNAs and mRNAs characterized by a regulatory relationship according to miRNA target prediction databases. The analysis identified 588 miRNA–target interactions between 102 miRNAs and 588 targets. Specifically, 63 upregulated miRNAs interacted with 295 downregulated targets, while 39 downregulated miRNAs were paired with 293 upregulated mRNA targets. Functional characterization of miRNA/mRNA association analysis highlighted hypoxia signaling, integrin, ephrin receptor signaling and regulation of actin-based motility by Rho among the canonical pathways regulated by E2 in HUVEC. Transcription factors and downstream genes analysis revealed eight networks, including those mediated by JUN and REPIN1, which are associated with cadherin binding and cell adhesion molecule binding pathways. Conclusion: This study identifies regulatory networks obtained by integrative microarray analysis and provides additional insights into the way estradiol could regulate endothelial function in human endothelial cells.

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EGFR-ERK induced activation of GRHL1 promotes cell cycle progression by up-regulating cell cycle related genes in lung cancer

Cell Death and Disease ◽

10.1038/s41419-021-03721-9 ◽

2021 ◽

Vol 12 (5) ◽

Author(s):

Yiming He ◽

Mingxi Gan ◽

Yanan Wang ◽

Tong Huang ◽

Jianbin Wang ◽

...

Keyword(s):

Lung Cancer ◽

Cell Cycle ◽

Cell Cycle Progression ◽

Potential Role ◽

Target Genes ◽

Nuclear Translocation ◽

Phosphorylation Site ◽

Promoter Regions ◽

Cycle Progression

AbstractGrainyhead-like 1 (GRHL1) is a transcription factor involved in embryonic development. However, little is known about the biological functions of GRHL1 in cancer. In this study, we found that GRHL1 was upregulated in non-small cell lung cancer (NSCLC) and correlated with poor survival of patients. GRHL1 overexpression promoted the proliferation of NSCLC cells and knocking down GRHL1 inhibited the proliferation. RNA sequencing showed that a series of cell cycle-related genes were altered when knocking down GRHL1. We further demonstrated that GRHL1 could regulate the expression of cell cycle-related genes by binding to the promoter regions and increasing the transcription of the target genes. Besides, we also found that EGF stimulation could activate GRHL1 and promoted its nuclear translocation. We identified the key phosphorylation site at Ser76 on GRHL1 that is regulated by the EGFR-ERK axis. Taken together, these findings elucidate a new function of GRHL1 on regulating the cell cycle progression and point out the potential role of GRHL1 as a drug target in NSCLC.

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