The gep oncogenes, Galpha(12) and Galpha(13), upregulate the transforming growth factor-beta1 gene

Transforming growth factor-beta1 (TGFbeta1) plays a role in neoplastic transformation and transdifferentiation. Galpha(12) and Galpha(13), referred to as the gep oncogenes, stimulate mitogenic pathways. Nonetheless, no information is available regarding their roles in the regulation of the TGFbeta1 gene and the molecules linking them to gene transcription. Knockdown or knockout experiments using murine embryonic fibroblasts and hepatic stellate cells indicated that a Galpha(12) and Galpha(13) deficiency reduced constitutive, auto-stimulatory or thrombin-inducible TGFbeta1 gene expression. In contrast, transfection of activated mutants of Galpha(12) and Galpha(13) enabled the knockout cells to promote TGFbeta1 induction. A promoter deletion analysis suggested that activating protein 1 (AP-1) plays a role in TGFbeta1 gene transactivation, which was corroborated by the observation that a deficiency of the G-proteins decreased the AP-1 activity, whereas their activation enhanced it. Moreover, mutation of the AP-1-binding site abrogated the ability of Galpha(12) and Galpha(13) to induce the TGFbeta1 gene. Transfection of a dominant-negative mutant of Rho or Rac, but not Cdc42, prevented gene transactivation and decreased AP-1 activity downstream of Galpha(12) and Galpha(13). In summary, Galpha(12) and Galpha(13) regulate the expression of the TGFbeta1 gene through an increase in Rho/Rac-dependent AP-1 activity, implying that the G-protein-coupled receptor (GPCR)-Galpha(12) pathway is involved in the TGFbeta1-mediated transdifferentiation process.

Medienart:

E-Artikel

Erscheinungsjahr:

2009

Erschienen:

2009

Enthalten in:

Zur Gesamtaufnahme - volume:28

Enthalten in:

Oncogene - 28(2009), 9 vom: 05. März, Seite 1230-40

Sprache:

Englisch

Beteiligte Personen:

Lee, S J [VerfasserIn]
Yang, J W [VerfasserIn]
Cho, I J [VerfasserIn]
Kim, W D [VerfasserIn]
Cho, M K [VerfasserIn]
Lee, C H [VerfasserIn]
Kim, S G [VerfasserIn]

Links:

Volltext

Themen:

DNA Primers
EC 3.6.5.1
GTP-Binding Protein alpha Subunits, G12-G13
Journal Article
Research Support, Non-U.S. Gov't
Transcription Factor AP-1
Transforming Growth Factor beta

Anmerkungen:

Date Completed 30.03.2009

Date Revised 19.11.2009

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1038/onc.2008.488

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM185820514