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Solution Structures of PPARγ2/RXRα Complexes.

Osz J, Pethoukhov MV, Sirigu S, Svergun DI, Moras D, Rochel N - PPAR Res (2012)

Bottom Line: PPARγ is a key regulator of glucose homeostasis and insulin sensitization.PPARγ must heterodimerize with its dimeric partner, the retinoid X receptor (RXR), to bind DNA and associated coactivators such as p160 family members or PGC-1α to regulate gene networks.The solution structures reveal an asymmetry of the overall structure due to the crucial role of the DNA in positioning the heterodimer and indicate asymmetrical binding of TIF2 to the heterodimer.

View Article: PubMed Central - PubMed

Affiliation: Department of Integrative Structural Biology, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Centre National de Recherche Scientifique (CNRS) UMR 7104, Institut National de Santé et de Recherche Médicale (INSERM) U964, Université de Strasbourg, 67404 Illkirch, France.

ABSTRACT
PPARγ is a key regulator of glucose homeostasis and insulin sensitization. PPARγ must heterodimerize with its dimeric partner, the retinoid X receptor (RXR), to bind DNA and associated coactivators such as p160 family members or PGC-1α to regulate gene networks. To understand how coactivators are recognized by the functional heterodimer PPARγ/RXRα and to determine the topological organization of the complexes, we performed a structural study using small angle X-ray scattering of PPARγ/RXRα in complex with DNA from regulated gene and the TIF2 receptor interacting domain (RID). The solution structures reveal an asymmetry of the overall structure due to the crucial role of the DNA in positioning the heterodimer and indicate asymmetrical binding of TIF2 to the heterodimer.

No MeSH data available.


Related in: MedlinePlus

Biophysical characterization of the stoichiometry of the TIF2 RID/PPARγ/RXR complexes. (a) Structural organization of hPPARγ1, hPPARγ2, and hTIF2. (b) ESI mass spectra of TIF2 RID/PPARγ/RXR LBDs recorded under nondenaturing conditions in 200 mM ammonium acetate at pH = 7.4. The different charge states of the proteins are indicated above the peaks. The calculated molecular mass of the first peak corresponds to PPARγ/RXRα LBDs and the second one to the complex containing one PPARγ/RXRα LBDs dimer and one TIF2 RID. (c) Sedimentation equilibrium experiments. Best fits of experimental data for TIF2 RID/PPARγΔNTD/RXRΔNTD at 12,000 rpm with the self-association methods (SedPhat program). Sedimentation equilibrium data agrees with one TIF2 RID bound to PPARγΔNTD/RXRΔNTD.
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fig1: Biophysical characterization of the stoichiometry of the TIF2 RID/PPARγ/RXR complexes. (a) Structural organization of hPPARγ1, hPPARγ2, and hTIF2. (b) ESI mass spectra of TIF2 RID/PPARγ/RXR LBDs recorded under nondenaturing conditions in 200 mM ammonium acetate at pH = 7.4. The different charge states of the proteins are indicated above the peaks. The calculated molecular mass of the first peak corresponds to PPARγ/RXRα LBDs and the second one to the complex containing one PPARγ/RXRα LBDs dimer and one TIF2 RID. (c) Sedimentation equilibrium experiments. Best fits of experimental data for TIF2 RID/PPARγΔNTD/RXRΔNTD at 12,000 rpm with the self-association methods (SedPhat program). Sedimentation equilibrium data agrees with one TIF2 RID bound to PPARγΔNTD/RXRΔNTD.

Mentions: The actions of PPARγ are mediated by 2 isoforms that result from alternative splicing. PPARγ2 is 28 amino acids longer at the N-terminal end (Figure 1(a)) and is mainly expressed in adipocyte cells, while PPARγ1 is ubiquitously expressed. Interestingly, PPARγ2 is ten times more active in ligand-independent transcriptional activation than PPARγ1 [7, 8].


Solution Structures of PPARγ2/RXRα Complexes.

Osz J, Pethoukhov MV, Sirigu S, Svergun DI, Moras D, Rochel N - PPAR Res (2012)

Biophysical characterization of the stoichiometry of the TIF2 RID/PPARγ/RXR complexes. (a) Structural organization of hPPARγ1, hPPARγ2, and hTIF2. (b) ESI mass spectra of TIF2 RID/PPARγ/RXR LBDs recorded under nondenaturing conditions in 200 mM ammonium acetate at pH = 7.4. The different charge states of the proteins are indicated above the peaks. The calculated molecular mass of the first peak corresponds to PPARγ/RXRα LBDs and the second one to the complex containing one PPARγ/RXRα LBDs dimer and one TIF2 RID. (c) Sedimentation equilibrium experiments. Best fits of experimental data for TIF2 RID/PPARγΔNTD/RXRΔNTD at 12,000 rpm with the self-association methods (SedPhat program). Sedimentation equilibrium data agrees with one TIF2 RID bound to PPARγΔNTD/RXRΔNTD.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3539437&req=5

fig1: Biophysical characterization of the stoichiometry of the TIF2 RID/PPARγ/RXR complexes. (a) Structural organization of hPPARγ1, hPPARγ2, and hTIF2. (b) ESI mass spectra of TIF2 RID/PPARγ/RXR LBDs recorded under nondenaturing conditions in 200 mM ammonium acetate at pH = 7.4. The different charge states of the proteins are indicated above the peaks. The calculated molecular mass of the first peak corresponds to PPARγ/RXRα LBDs and the second one to the complex containing one PPARγ/RXRα LBDs dimer and one TIF2 RID. (c) Sedimentation equilibrium experiments. Best fits of experimental data for TIF2 RID/PPARγΔNTD/RXRΔNTD at 12,000 rpm with the self-association methods (SedPhat program). Sedimentation equilibrium data agrees with one TIF2 RID bound to PPARγΔNTD/RXRΔNTD.
Mentions: The actions of PPARγ are mediated by 2 isoforms that result from alternative splicing. PPARγ2 is 28 amino acids longer at the N-terminal end (Figure 1(a)) and is mainly expressed in adipocyte cells, while PPARγ1 is ubiquitously expressed. Interestingly, PPARγ2 is ten times more active in ligand-independent transcriptional activation than PPARγ1 [7, 8].

Bottom Line: PPARγ is a key regulator of glucose homeostasis and insulin sensitization.PPARγ must heterodimerize with its dimeric partner, the retinoid X receptor (RXR), to bind DNA and associated coactivators such as p160 family members or PGC-1α to regulate gene networks.The solution structures reveal an asymmetry of the overall structure due to the crucial role of the DNA in positioning the heterodimer and indicate asymmetrical binding of TIF2 to the heterodimer.

View Article: PubMed Central - PubMed

Affiliation: Department of Integrative Structural Biology, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Centre National de Recherche Scientifique (CNRS) UMR 7104, Institut National de Santé et de Recherche Médicale (INSERM) U964, Université de Strasbourg, 67404 Illkirch, France.

ABSTRACT
PPARγ is a key regulator of glucose homeostasis and insulin sensitization. PPARγ must heterodimerize with its dimeric partner, the retinoid X receptor (RXR), to bind DNA and associated coactivators such as p160 family members or PGC-1α to regulate gene networks. To understand how coactivators are recognized by the functional heterodimer PPARγ/RXRα and to determine the topological organization of the complexes, we performed a structural study using small angle X-ray scattering of PPARγ/RXRα in complex with DNA from regulated gene and the TIF2 receptor interacting domain (RID). The solution structures reveal an asymmetry of the overall structure due to the crucial role of the DNA in positioning the heterodimer and indicate asymmetrical binding of TIF2 to the heterodimer.

No MeSH data available.


Related in: MedlinePlus