scholarly journals Ectopic expression of Cdk6 circumvents transforming growth factor-β mediated growth inhibition

Oncogene ◽  
2001 ◽  
Vol 20 (41) ◽  
pp. 5888-5896 ◽  
Author(s):  
Fan Zhang ◽  
Minna Taipale ◽  
Annamari Heiskanen ◽  
Marikki Laiho
Keyword(s):  
Growth Factor ◽  
Growth Inhibition ◽  
Transforming Growth Factor ◽  
Ectopic Expression ◽  
Transforming Growth Factor Β

scholarly journals BF-1 Interferes with Transforming Growth Factor β Signaling by Associating with Smad Partners

2000 ◽  
Vol 20 (17) ◽  
pp. 6201-6211 ◽  
Author(s):  
Changlin Dou ◽  
Jun Lee ◽  
Bo Liu ◽  
Fang Liu ◽  
Joan Massague ◽  
...  
Keyword(s):  
Growth Factor ◽  
Dna Binding ◽  
Growth Inhibition ◽  
Progenitor Cells ◽  
Transcriptional Activation ◽  
Transforming Growth Factor ◽  
Ectopic Expression ◽  
Transforming Growth Factor Β ◽  
Reporter System ◽  
Transcriptional Responses

ABSTRACT The winged-helix (WH) BF-1 gene, which encodes brain factor 1 (BF-1) (also known as foxg1), is essential for the proliferation of the progenitor cells of the cerebral cortex. Here we show that BF-1-deficient telencephalic progenitor cells are more apt to leave the cell cycle in response to transforming growth factor β (TGF-β) and activin. We found that ectopic expression of BF-1 in vitro inhibits TGF-β mediated growth inhibition and transcriptional activation. Surprisingly, we found that the ability of BF-1 to function as a TGF-β antagonist does not require its DNA binding activity. Therefore, we investigated whether BF-1 can inhibit Smad-dependent transcriptional responses by interacting with Smads or Smad binding partners. We found that BF-1 does not interact with Smads. Because the identities of the Smad partners mediating growth inhibition by TGF-β are not clearly established, we examined a model reporter system which is known to be activated by activin and TGF-β through Smads and the WH factor FAST-2. We demonstrate that BF-1 associates with FAST-2. This interaction is dependent on the same region of protein which mediates its ability to interfere with the antiproliferative activity of TGF-β and with TGF-β-dependent transcriptional activation. Furthermore, the interaction of FAST-2 with BF-1 is mediated by the same domain which is required for FAST-2 to interact with Smad2. We propose a model in which BF-1 interferes with transcriptional responses to TGF-β by interacting with FAST-2 or with other DNA binding proteins which function as Smad2 partners and which have a common mode of interaction with Smad2.

scholarly journals A Functional Connection between pRB and Transforming Growth Factor β in Growth Inhibition and Mammary Gland Development

2009 ◽  
Vol 29 (16) ◽  
pp. 4455-4466 ◽  
Author(s):  
Sarah M. Francis ◽  
Jacqueline Bergsied ◽  
Christian E. Isaac ◽  
Courtney H. Coschi ◽  
Alison L. Martens ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Growth Factor ◽  
Growth Inhibition ◽  
Mammary Gland Development ◽  
Transforming Growth Factor ◽  
Critical Role ◽  
Transforming Growth Factor Β ◽  
Mammary Development ◽  
Functional Connection ◽  
Gland Development

ABSTRACT Transforming growth factor β (TGF-β) is a crucial mediator of breast development, and loss of TGF-β-induced growth arrest is a hallmark of breast cancer. TGF-β has been shown to inhibit cyclin-dependent kinase (CDK) activity, which leads to the accumulation of hypophosphorylated pRB. However, unlike other components of TGF-β cytostatic signaling, pRB is thought to be dispensable for mammary development. Using gene-targeted mice carrying subtle missense changes in pRB (Rb1 ΔL and Rb1NF ), we have discovered that pRB plays a critical role in mammary gland development. In particular, Rb1 mutant female mice have hyperplastic mammary epithelium and defects in nursing due to insensitivity to TGF-β growth inhibition. In contrast with previous studies that highlighted the inhibition of cyclin/CDK activity by TGF-β signaling, our experiments revealed that active transcriptional repression of E2F target genes by pRB downstream of CDKs is also a key component of TGF-β cytostatic signaling. Taken together, our work demonstrates a unique functional connection between pRB and TGF-β in growth control and mammary gland development.

scholarly journals Association of v-ErbA with Smad4 Disrupts TGF-β Signaling

2009 ◽  
Vol 20 (5) ◽  
pp. 1509-1519 ◽  
Author(s):  
Richard A. Erickson ◽  
Xuedong Liu
Keyword(s):  
Growth Factor ◽  
Cell Growth ◽  
Growth Inhibition ◽  
Transforming Growth Factor ◽  
Mechanistic Explanation ◽  
Transforming Growth Factor Β ◽  
Cell Growth Inhibition ◽  
Erythroleukemia Cells ◽  
Avian Erythroblastosis Virus

Disruption of the transforming growth factor-β (TGF-β) pathway is observed in the majority of cancers. To further understand TGF-β pathway inactivation in cancer, we stably expressed the v-ErbA oncoprotein in TGF-β responsive cells. v-ErbA participates in erythroleukemic transformation of cells induced by the avian erythroblastosis virus (AEV). Here we demonstrate that expression of v-ErbA was sufficient to antagonize TGF-β–induced cell growth inhibition and that dysregulation of TGF-β signaling required that v-ErbA associate with the Smad4 which sequesters Smad4 in the cytoplasm. We also show that AEV-transformed erythroleukemia cells were resistant to TGF-β–induced growth inhibition and that TGF-β sensitivity could be recovered by reducing v-ErbA expression. Our results reveal a novel mechanism for oncogenic disruption of TGF-β signaling and provide a mechanistic explanation of v-ErbA activity in AEV-induced erythroleukemia.

scholarly journals Constitutive Smad linker phosphorylation in melanoma: a mechanism of resistance to transforming growth factor-β-mediated growth inhibition

2011 ◽  
Vol 24 (3) ◽  
pp. 512-524 ◽  
Author(s):  
Karine A. Cohen-Solal ◽  
Kim T. Merrigan ◽  
Joseph L.-K. Chan ◽  
James S. Goydos ◽  
Wenjin Chen ◽  
...  
Keyword(s):  
Growth Factor ◽  
Growth Inhibition ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Mechanism Of Resistance

scholarly journals Suppression of Transforming Growth Factor β Receptor 2 and Smad5 Is Associated with High Levels of MicroRNA miR-155 in the Oral Mucosa during Chronic Simian Immunodeficiency Virus Infection

2014 ◽  
Vol 89 (5) ◽  
pp. 2972-2978 ◽  
Author(s):  
Jeffy George ◽  
Mark G. Lewis ◽  
Rolf Renne ◽  
Joseph J. Mattapallil
Keyword(s):  
Growth Factor ◽  
Simian Immunodeficiency Virus ◽  
Transforming Growth Factor ◽  
Ectopic Expression ◽  
Transforming Growth Factor Β ◽  
Mucosal Inflammation ◽  
Tgfβ Signaling ◽  
Immunodeficiency Virus ◽  
Siv Infection

Chronic human immunodeficiency virus and simian immunodeficiency virus (HIV and SIV) infections are characterized by mucosal inflammation in the presence of anti-inflammatory cytokines such as transforming growth factor β (TGFβ). The mechanisms for refractiveness to TGFβ are not clear. Here we show that the expression of microRNA miR-155 was significantly upregulated in the oropharyngeal mucosa during chronic SIV infection and was coincident with downregulation of TGFβ receptor 2 (TGFβ-R2) and SMAD5, key TGFβ signaling genes that harbor putative target sites for miR-155. Ectopic expression of miR-155in vitrowas found to significantly downregulate TGFβ-R2 and Smad5 expression, suggesting a role for miR-155 in the suppression of TGFβ-R2 and SMAD5 genesin vivo. The downregulation of TGFβ signaling genes by miR-155 likely contributes to the nonresponsiveness to TGFβ during SIV infection and may inadvertently aid in increased immune activation during HIV and SIV infections.

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