scholarly journals The Janus Kinase 2 Is Required for Expression and Nuclear Accumulation of Cyclin D1 in Proliferating Mammary Epithelial Cells

2007 ◽  
Vol 21 (8) ◽  
pp. 1877-1892 ◽  
Author(s):  
Kazuhito Sakamoto ◽  
Bradley A. Creamer ◽  
Aleata A. Triplett ◽  
Kay-Uwe Wagner
Keyword(s):  
Epithelial Cells ◽  
Cyclin D1 ◽  
Nuclear Export ◽  
Mammary Epithelial Cells ◽  
Glycogen Synthase ◽  
Mammary Epithelial ◽  
Janus Kinase ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3Β ◽  
Janus Kinase 2

Abstract Using a conditional knockout approach, we previously demonstrated that the Janus kinase 2 (Jak2) is crucial for prolactin (PRL) signaling and normal mammary gland development. PRL is suggested to synchronously activate multiple signaling cascades that emerge on the PRL receptor (PRLR). This study demonstrates that Jak2 is essential for the activation of the signal transducer and activator of transcription 5 (Stat5) and expression of Cish (cytokine-inducible SH2-containing protein), a Stat5-responsive negative regulator of Jak/Stat signaling. However, Jak2 is dispensable for the PRL-induced activation of c-Src, focal adhesion kinase, and the MAPK pathway. Despite activation of these kinases that are commonly associated with proliferative responses, the ablation of Jak2 reduces the multiplication of immortalized mammary epithelial cells (MECs). Our studies show that signaling through Jak2 controls not only the transcriptional activation of the Cyclin D1 gene, but, more importantly, it regulates the accumulation of the Cyclin D1 protein in the nucleus by altering the activity of signal transducers that mediate the phosphorylation and subsequent nuclear export of Cyclin D1. In particular, the levels of activated Akt (protein kinase B) and inactive glycogen synthase kinase-3β (i.e. a kinase that regulates the nuclear export and degradation of Cyclin D1) are reduced in MECs lacking Jak2. The proliferation of Jak2-deficient MECs can be rescued by expressing of a mutant form of Cyclin D1 that cannot be phosphorylated by glycogen synthase kinase-3β and therefore constitutively resides in the nucleus. Besides discriminating Jak2-dependent and Jak2-independent signaling events emerging from the PRLR, our observations provide a possible mechanism for phenotypic similarities between Cyclin D1 knockouts and females lacking individual members of the PRLR signaling cascade, in particular the PRLR, Jak2, and Stat5.

scholarly journals ErbB2/Neu-Induced, Cyclin D1-Dependent Transformation Is Accelerated in p27-Haploinsufficient Mammary Epithelial Cells but Impaired in p27-Null Cells

2002 ◽  
Vol 22 (7) ◽  
pp. 2204-2219 ◽  
Author(s):  
Rebecca S. Muraoka ◽  
Anne E. G. Lenferink ◽  
Brian Law ◽  
Elizabeth Hamilton ◽  
Dana M. Brantley ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cyclin D1 ◽  
Nuclear Localization ◽  
Nuclear Export ◽  
Mammary Epithelial Cells ◽  
Cell Transformation ◽  
Mammary Epithelium ◽  
Tumor Formation ◽  
Mammary Epithelial ◽  
Cdk4 Activity

ABSTRACT ErbB2/Neu destabilizes the cyclin-dependent kinase (Cdk) inhibitor p27 and increases expression of cyclin D1. Therefore, we studied the roles of p27 and cyclin D1 in ErbB2-mediated mammary epithelial cell transformation. Overexpression of ErbB2 or cyclin D1 in p27+/− primary murine mammary epithelial cells resulted in increased proliferation, cyclin D1 nuclear localization, and colony formation in soft agar compared to those in p27+/+ cells. In contrast, ErbB2- or cyclin D1-overexpressing p27−/− cells displayed reduced proliferation, anchorage-independent growth, Cdk4 activity, cyclin D1 expression, and cyclin D1 nuclear localization compared to wild-type cells. A cyclin D1 mutation in its nuclear export sequence (T286A) partially rescued nuclear localization of cyclin D1 in p27−/− cells but did not increase proliferation or Cdk4 kinase activity. Overexpression of E2F1, however, increased proliferation to the same degree in p27+/+ , p27+/− , and p27−/− cells. Mammary glands from MMTV (mouse mammary tumor virus)-neu/p27+/− mice exhibited alveolar hyperplasia, enhanced proliferation, decreased apoptosis, and accelerated tumor formation compared to MMTV-neu/p27+/+ glands. However, MMTV-neu/p27−/− glands showed decreased proliferation, cyclin D1 expression, and Cdk4 activity, as well as markedly prolonged tumor latency, compared to MMTV-neu/p27+/+ glands. These results suggest that p27+/− mammary epithelium may be more susceptible to oncogene-induced tumorigenesis, whereas p27-null glands, due to severely impaired cyclin D1/Cdk4 function, are more resistant to transformation.

Effects of hyperactive Janus kinase 2 signaling in mammary epithelial cells

2002 ◽  
Vol 296 (1) ◽  
pp. 139-144 ◽  
Author(s):  
Hanne Olsen ◽  
Malin A Hedengran Faulds ◽  
Pipsa Saharinen ◽  
Olli Silvennoinen ◽  
Lars-Arne Haldosén
Keyword(s):  
Epithelial Cells ◽  
Mammary Epithelial Cells ◽  
Mammary Epithelial ◽  
Janus Kinase ◽  
Janus Kinase 2

scholarly journals c-erbB-3

2002 ◽  
Vol 157 (6) ◽  
pp. 929-940 ◽  
Author(s):  
Martin Offterdinger ◽  
Christian Schöfer ◽  
Klara Weipoltshammer ◽  
Thomas W. Grunt
Keyword(s):  
Epithelial Cells ◽  
Nuclear Localization ◽  
Nuclear Export ◽  
Mammary Epithelial Cells ◽  
Mammary Epithelial ◽  
Site Directed Mutagenesis ◽  
Receptor Protein ◽  
Erbb Receptors ◽  
Cell Fractionation ◽  
Epithelial Polarity

c-erbB receptors are usually located in cell membranes and are activated by extracellular binding of EGF-like growth factors. Unexpectedly, using immunofluorescence we found high levels of c-erbB-3 within the nuclei of MTSV1-7 immortalized nonmalignant human mammary epithelial cells. Nuclear localization was mediated by the COOH terminus of c-erbB-3, and a nuclear localization signal was identified by site-directed mutagenesis and by transfer of the signal to chicken pyruvate kinase. A nuclear export inhibitor caused accumulation of c-erbB-3 in the nuclei of other mammary epithelial cell lines as demonstrated by immunofluorescence and biochemical cell fractionation, suggesting that c-erbB-3 shuttles between nuclear and nonnuclear compartments in these cells. Growth of MTSV1-7 on permeable filters induced epithelial polarity and concentration of c-erbB-3 within the nucleoli. However, the c-erbB-3 ligand heregulin β1 shifted c-erbB-3 from the nucleolus into the nucleoplasm and then into the cytoplasm. The subcellular localization of c-erbB-3 obviously depends on exogenous stimuli and on the stage of epithelial polarity and challenges the specific function of c-erbB-3 as a transmembrane receptor protein arguing for additional, as yet unidentified, roles of c-erbB-3 within the nucle(ol)us of mammary epithelial cells.

scholarly journals PIN1 Is an E2F Target Gene Essential for Neu/Ras-Induced Transformation of Mammary Epithelial Cells

2002 ◽  
Vol 22 (15) ◽  
pp. 5281-5295 ◽  
Author(s):  
Akihide Ryo ◽  
Yih-Cherng Liou ◽  
Gerburg Wulf ◽  
Masafumi Nakamura ◽  
Sam W. Lee ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cyclin D1 ◽  
Transcriptional Activation ◽  
Target Gene ◽  
Mammary Epithelial Cells ◽  
Cell Transformation ◽  
Mammary Tumorigenesis ◽  
Mammary Epithelial ◽  
Oncogenic Signaling ◽  
And Function

ABSTRACT Oncogenes Neu/HER2/ErbB2 and Ras can induce mammary tumorigenesis via upregulation of cyclin D1. One major regulatory mechanism in these oncogenic signaling pathways is phosphorylation of serines or threonines preceding proline (pSer/Thr-Pro). Interestingly, the pSer/Thr-Pro motifs in proteins exist in two completely distinct cis and trans conformations, whose conversion is catalyzed specifically by the essential prolyl isomerase Pin1. By isomerizing pSer/Thr-Pro bonds, Pin1 can regulate the conformation and function of certain phosphorylated proteins. We have previously shown that Pin1 is overexpressed in breast tumors and positively regulates cyclin D1 by transcriptional activation and posttranslational stabilization. Moreover, in Pin1 knockout mice, mammary epithelial cells fail to undergo massive proliferation during pregnancy, as is the case in cyclin D1 null mice. These results indicate that Pin1 is upregulated in breast cancer and may be involved in mammary tumors. However, the mechanism of Pin1 overexpression in cancer and its significance in cell transformation remain largely unknown. Here we demonstrate that PIN1 expression is mediated by the transcription factor E2F and enhanced by c-Neu and Ha-Ras via E2F. Furthermore, overexpression of Pin1 not only confers transforming properties on mammary epithelial cells but also enhances the transformed phenotypes of Neu/Ras-transformed mammary epithelial cells. In contrast, inhibition of Pin1 suppresses Neu- and Ras-induced transformed phenotypes, which can be fully rescued by overexpression of a constitutively active cyclin D1 mutant that is refractory to the Pin1 inhibition. Thus, Pin1 is an E2F target gene that is essential for the Neu/Ras-induced transformation of mammary epithelial cells through activation of cyclin D1.

scholarly journals Dipeptide (Methionyl-Methionine) Transport and Its Effect on β-Casein Synthesis in Bovine Mammary Epithelial Cells

2018 ◽  
Vol 49 (2) ◽  
pp. 479-488 ◽  
Author(s):  
Caihong Wang ◽  
Fengqi Zhao ◽  
Jianxin Liu ◽  
Hongyun Liu
Keyword(s):  
Epithelial Cells ◽  
Cell Viability ◽  
Transport Properties ◽  
Mammary Epithelial Cells ◽  
Mammary Epithelial ◽  
Janus Kinase ◽  
Initiation Factor ◽  
Peptide Transporter ◽  
Small Interference Rna ◽  
Bovine Mammary Epithelial Cells

Background/Aims: The aim of this study was to investigate the transport properties and utilization of methionyl-methionine dipeptide (Met-Met) in β-casein (β-CN) synthesis in bovine mammary epithelial cells (BMECs). Methods: The transport properties were studied for the effects of time, pH, concentration, temperature and inhibitors using Met-Met-FITC in BMECs. BMECs were treated with different concentrations of Met-Met (0, 20, 40, 80, 120 and 160 µg/ml). In several experiments, the cells were treated with Janus kinase 2 (JAK2) inhibitor (tyrphostin AG-490, 50 µM) and mammalian target of rapamycin (mTOR) inhibitor (rapamycin, 100 ng/ml). Results: The uptake of Met-Met-FITC by BMECs was rapid during the first fifteen minutes and became saturated after 15 minutes. The transport of Met-Met-FITC in BMECs exhibited a Michaelis constant of 52.4 µM and maximum transport velocity of 14.8 pmol/min/mg protein. The uptake of Met-Met-FITC in BMECs was pH-dependent, peaked at pH 6.5 and was significantly inhibited by other peptides, including Met-Lys, Lys-Lys, Gly-Met, Gly-Leu and Met-Leu. Knocking down the peptide transporter 2 (PepT2) with small interference RNA markedly decreased Met-Met-FITC uptake. Met-Met concentration-dependently increased the PepT2 expression and β-CN synthesis in BMECs with an optimal concentration of 80 µg/ml. At 80 µg/ml, Met-Met also enhanced the cell viability and cyclin D1 expression and promoted cell cycle transition from G1 phase to S phase. In addition, 80 µg/ml Met-Met increased the mRNA abundance of JAK2 and signal transducer and activator of transcription 5 (STAT5) and enhanced the phosphorylation of JAK2, STAT5, mTOR, p70 ribosomal S6 kinase 1 and eukaryotic initiation factor 4E binding protein 1. The inhibition of JAK2 and mTOR significantly decreased Met-Met-induced increase in cell viability and β-CN synthesis in BMECs. Conclusion: Our data elucidated the properties of peptide transporter and its effect on β-CN synthesis in BMECs. Met-Met, taken up by PepT2, enhances cell proliferation and promotes β-CN synthesis by activating JAK2-STAT5 and mTOR signaling pathways in BMECs.

scholarly journals Glycogen synthase kinase 3β and cyclin D1 expression in cervical carcinogenesis

2016 ◽  
Vol 59 (6) ◽  
pp. 470 ◽  
Author(s):  
Hyunsoo Park ◽  
Myunghwa Lee ◽  
Dae Woon Kim ◽  
Seo Yoo Hong ◽  
Hojung Lee
Keyword(s):  
Cyclin D1 ◽  
Glycogen Synthase ◽  
Glycogen Synthase Kinase ◽  
Cervical Carcinogenesis ◽  
Glycogen Synthase Kinase 3Β

scholarly journals The Ras oncogene signals centrosome amplification in mammary epithelial cells through cyclin D1/Cdk4 and Nek2

Oncogene ◽  
2010 ◽  
Vol 29 (36) ◽  
pp. 5103-5112 ◽  
Author(s):  
X Zeng ◽  
F Y Shaikh ◽  
M K Harrison ◽  
A M Adon ◽  
A J Trimboli ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cyclin D1 ◽  
Mammary Epithelial Cells ◽  
Centrosome Amplification ◽  
Mammary Epithelial ◽  
Ras Oncogene
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