Sorting nexin 9 differentiates ligand-activated Smad3 from Smad2 for nuclear import and transforming growth factor β signaling

Transforming growth factor β (TGFβ) is a pleiotropic protein secreted from essentially all cell types and primary tissues. While TGFβ’s actions reflect the activity of a number of signaling networks, the primary mediator of TGFβ responses are the Smad proteins. Following receptor activation, these cytoplasmic proteins form hetero-oligomeric complexes that translocate to the nucleus and affect gene transcription. Here, through biological, biochemical, and immunofluorescence approaches, sorting nexin 9 (SNX9) is identified as being required for Smad3-dependent responses. SNX9 interacts with phosphorylated (p) Smad3 independent of Smad2 or Smad4 and promotes more rapid nuclear delivery than that observed independent of ligand. Although SNX9 does not bind nucleoporins Nup153 or Nup214 or some β importins (Imp7 or Impβ), it mediates the association of pSmad3 with Imp8 and the nuclear membrane. This facilitates nuclear translocation of pSmad3 but not SNX9.

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Transforming Growth Factor β-Mediated Transcriptional Repression of c-myc Is Dependent on Direct Binding of Smad3 to a Novel Repressive Smad Binding Element

Molecular and Cellular Biology ◽

10.1128/mcb.24.6.2546-2559.2004 ◽

2004 ◽

Vol 24 (6) ◽

pp. 2546-2559 ◽

Cited By ~ 159

Author(s):

Joshua P. Frederick ◽

Nicole T. Liberati ◽

David S. Waddell ◽

Yigong Shi ◽

Xiao-Fan Wang

Keyword(s):

Growth Factor ◽

Transcriptional Repression ◽

Molecular Mechanisms ◽

Target Genes ◽

Transforming Growth Factor ◽

Transforming Growth Factor Β ◽

Cell Types ◽

Specific Cell ◽

Smad Proteins ◽

Smad Binding Element

ABSTRACT Smad proteins are the most well-characterized intracellular effectors of the transforming growth factor β (TGF-β) signal. The ability of the Smads to act as transcriptional activators via TGF-β-induced recruitment to Smad binding elements (SBE) within the promoters of TGF-β target genes has been firmly established. However, the elucidation of the molecular mechanisms involved in TGF-β-mediated transcriptional repression are only recently being uncovered. The proto-oncogene c-myc is repressed by TGF-β, and this repression is required for the manifestation of the TGF-β cytostatic program in specific cell types. We have shown that Smad3 is required for both TGF-β-induced repression of c-myc and subsequent growth arrest in keratinocytes. The transcriptional repression of c-myc is dependent on direct Smad3 binding to a novel Smad binding site, termed a repressive Smad binding element (RSBE), within the TGF-β inhibitory element (TIE) of the c-myc promoter. The c-myc TIE is a composite element, comprised of an overlapping RSBE and a consensus E2F site, that is capable of binding at least Smad3, Smad4, E2F-4, and p107. The RSBE is distinct from the previously defined SBE and may partially dictate, in conjunction with the promoter context of the overlapping E2F site, whether the Smad3-containing complex actively represses, as opposed to transactivates, the c-myc promoter.

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CREB binding protein is a required coactivator for Smad-dependent, transforming growth factor β transcriptional responses in endothelial cells

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.95.16.9506 ◽

1998 ◽

Vol 95 (16) ◽

pp. 9506-9511 ◽

Cited By ~ 127

Author(s):

James N. Topper ◽

Maria R. DiChiara ◽

Jonathan D. Brown ◽

Amy J. Williams ◽

Dean Falb ◽

...

Keyword(s):

Endothelial Cells ◽

Growth Factor ◽

Transforming Growth Factor ◽

Binding Protein ◽

Transforming Growth Factor Β ◽

Cell Types ◽

Creb Binding Protein ◽

Transcriptional Responses ◽

Smad Proteins ◽

Smad Protein

The transforming growth factor-β (TGF-β) superfamily of growth factors and cytokines has been implicated in a variety of physiological and developmental processes within the cardiovascular system. Smad proteins are a recently described family of intracellular signaling proteins that transduce signals in response to TGF-β superfamily ligands. We demonstrate by both a mammalian two-hybrid and a biochemical approach that human Smad2 and Smad4, two essential Smad proteins involved in mediating TGF-β transcriptional responses in endothelial and other cell types, can functionally interact with the transcriptional coactivator CREB binding protein (CBP). This interaction is specific in that it requires ligand (TGF-β) activation and is mediated by the transcriptional activation domains of the Smad proteins. A closely related, but distinct endothelial-expressed Smad protein, Smad7, which does not activate transcription in endothelial cells, does not interact with CBP. Furthermore, Smad2,4–CBP interactions involve the COOH terminus of CBP, a region that interacts with other regulated transcription factors such as certain signal transduction and transcription proteins and nuclear receptors. Smad–CBP interactions are required for Smad-dependent TGF-β-induced transcriptional responses in endothelial cells, as evidenced by inhibition with overexpressed 12S E1A protein and reversal of this inhibition with exogenous CBP. This report demonstrates a functional interaction between Smad proteins and an essential component of the mammalian transcriptional apparatus (CBP) and extends our insight into how Smad proteins may regulate transcriptional responses in many cell types. Thus, functional Smad–coactivator interactions may be an important locus of signal integration in endothelial cells.

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Transforming growth factor β (TGF β) and activin stimulate nuclear translocation of Smad proteins in granulosa cells.

Fertility and Sterility ◽

10.1016/s0015-0282(01)02131-8 ◽

2001 ◽

Vol 76 (3) ◽

pp. S38

Author(s):

E.A. McGee ◽

J.I. Oakley ◽

J. Xu

Keyword(s):

Growth Factor ◽

Granulosa Cells ◽

Transforming Growth Factor ◽

Nuclear Translocation ◽

Transforming Growth Factor Β ◽

Smad Proteins

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Internalization-Dependent and -Independent Requirements for Transforming Growth Factor β Receptor Signaling via the Smad Pathway

Molecular and Cellular Biology ◽

10.1128/mcb.22.13.4750-4759.2002 ◽

2002 ◽

Vol 22 (13) ◽

pp. 4750-4759 ◽

Cited By ~ 129

Author(s):

Sumedha G. Penheiter ◽

Hugh Mitchell ◽

Nandor Garamszegi ◽

Maryanne Edens ◽

Jules J. E. Doré, ◽

...

Keyword(s):

Growth Factor ◽

Transforming Growth Factor ◽

Nuclear Translocation ◽

Transforming Growth Factor Β ◽

Receptor Activation ◽

Endocytic Pathway ◽

Type I ◽

Smad Pathway ◽

Sequence Of Events ◽

Β Receptor

ABSTRACT Members of the transforming growth factor β (TGF-β) family of proteins signal through cell surface transmembrane serine/threonine protein kinases known as type I and type II receptors. The TGF-β signal is extended through phosphorylation of receptor-associated Smad proteins by the type I receptor. Although numerous investigations have established the sequence of events in TGF-β receptor (TGF-βR) activation, none have examined the role of the endocytic pathway in initiation and/or maintenance of the signaling response. In this study we investigated whether TGF-βR internalization modulates type I receptor activation, the formation of a functional receptor/Smad/SARA complex, Smad2/3 phosphorylation or nuclear translocation, and TGF-β-dependent reporter gene activity. Our data provide evidence that, whereas type I receptor phosphorylation and association of SARA and Smad2 with the TGF-βR complex take place independently of clathrin lattice formation, Smad2 or Smad3 activation and downstream signaling only occur after endocytic vesicle formation. Thus, TGF-βR endocytosis is not simply a way to dampen the signaling response but instead is required to propagate signaling via the Smad pathway.

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The human NUPR1/P8 gene is transcriptionally activated by transforming growth factor β via the SMAD signalling pathway

Biochemical Journal ◽

10.1042/bj20120368 ◽

2012 ◽

Vol 445 (2) ◽

pp. 285-293 ◽

Cited By ~ 17

Author(s):

Roxane M. Pommier ◽

Johann Gout ◽

David F. Vincent ◽

Carla E. Cano ◽

Bastien Kaniewski ◽

...

Keyword(s):

Growth Factor ◽

Cancer Progression ◽

Stress Resistance ◽

Nuclear Protein ◽

Transforming Growth Factor ◽

Transforming Growth Factor Β ◽

Transcriptional Level ◽

Smad Proteins ◽

Activation Cascade ◽

Tgfβ Superfamily

NUPR1 (nuclear protein 1), also called P8 (molecular mass 8 kDa) or COM1 (candidate of metastasis 1), is involved in the stress response and in cancer progression. In the present study, we investigated whether human NUPR1 expression was regulated by TGFβ (transforming growth factor β), a secreted polypeptide largely involved in tumorigenesis. We demonstrate that the expression of NUPR1 was activated by TGFβ at the transcriptional level. We show that this activation is mediated by the SMAD proteins, which are transcription factors specifically involved in the signalling of TGFβ superfamily members. NUPR1 promoter analysis reveals the presence of a functional TGFβ-response element binding the SMAD proteins located in the genomic DNA region corresponding to the 5′-UTR (5′-untranslated region). Altogether, the molecular results of the present study, which demonstrate the existence of a TGFβ/SMAD/NUPR1 activation cascade, open the way to consider and investigate further a new mechanism enabling TGFβ to promote tumorigenesis by inducing stress resistance.

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Transforming growth factor–β in tissue fibrosis

Journal of Experimental Medicine ◽

10.1084/jem.20190103 ◽

2020 ◽

Vol 217 (3) ◽

Cited By ~ 6

Author(s):

Nikolaos G. Frangogiannis

Keyword(s):

Extracellular Matrix ◽

Growth Factor ◽

Epithelial Cells ◽

Transforming Growth Factor ◽

Transforming Growth Factor Β ◽

Cell Types ◽

Cellular Targets ◽

Extracellular Matrix Molecules ◽

Interacting Networks

TGF-β is extensively implicated in the pathogenesis of fibrosis. In fibrotic lesions, spatially restricted generation of bioactive TGF-β from latent stores requires the cooperation of proteases, integrins, and specialized extracellular matrix molecules. Although fibroblasts are major targets of TGF-β, some fibrogenic actions may reflect activation of other cell types, including macrophages, epithelial cells, and vascular cells. TGF-β–driven fibrosis is mediated through Smad-dependent or non-Smad pathways and is modulated by coreceptors and by interacting networks. This review discusses the role of TGF-β in fibrosis, highlighting mechanisms of TGF-β activation and signaling, the cellular targets of TGF-β actions, and the challenges of therapeutic translation.

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Inhibition of Transforming Growth Factor-β–Mediated Immunosuppression in Tumor-Draining Lymph Nodes Augments Antitumor Responses by Various Immunologic Cell Types

Cancer Research ◽

10.1158/0008-5472.can-08-2499 ◽

2009 ◽

Vol 69 (12) ◽

pp. 5142-5150 ◽

Cited By ~ 23

Author(s):

Takuya Fujita ◽

Koji Teramoto ◽

Yoshitomo Ozaki ◽

Jun Hanaoka ◽

Noriaki Tezuka ◽

...

Keyword(s):

Growth Factor ◽

Lymph Nodes ◽

Transforming Growth Factor ◽

Transforming Growth Factor Β ◽

Cell Types ◽

Draining Lymph Nodes

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Transforming Growth Factor-β Signaling in Fibrotic Diseases and Cancer-Associated Fibroblasts

Biomolecules ◽

10.3390/biom10121666 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1666

Author(s):

Xueke Shi ◽

Christian D. Young ◽

Hongmei Zhou ◽

Xiao-Jing Wang

Keyword(s):

Growth Factor ◽

Cancer Progression ◽

Immune Cells ◽

Transforming Growth Factor ◽

Transforming Growth Factor Β ◽

Cell Types ◽

Cancer Associated Fibroblasts ◽

The Matrix ◽

Fibrotic Diseases ◽

Fibrotic Disorders

Transforming growth factor-β (TGF-β) signaling is essential in embryo development and maintaining normal homeostasis. Extensive evidence shows that TGF-β activation acts on several cell types, including epithelial cells, fibroblasts, and immune cells, to form a pro-fibrotic environment, ultimately leading to fibrotic diseases. TGF-β is stored in the matrix in a latent form; once activated, it promotes a fibroblast to myofibroblast transition and regulates extracellular matrix (ECM) formation and remodeling in fibrosis. TGF-β signaling can also promote cancer progression through its effects on the tumor microenvironment. In cancer, TGF-β contributes to the generation of cancer-associated fibroblasts (CAFs) that have different molecular and cellular properties from activated or fibrotic fibroblasts. CAFs promote tumor progression and chronic tumor fibrosis via TGF-β signaling. Fibrosis and CAF-mediated cancer progression share several common traits and are closely related. In this review, we consider how TGF-β promotes fibrosis and CAF-mediated cancer progression. We also discuss recent evidence suggesting TGF-β inhibition as a defense against fibrotic disorders or CAF-mediated cancer progression to highlight the potential implications of TGF-β-targeted therapies for fibrosis and cancer.

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