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Mitochondrial fusion is increased by the nuclear coactivator PGC-1beta.

Liesa M, Borda-d'Agua B, Medina-Gómez G, Lelliott CJ, Paz JC, Rojo M, Palacín M, Vidal-Puig A, Zorzano A - PLoS ONE (2008)

Bottom Line: Here, we demonstrate that reduced mitochondrial size observed in knock-out mice for the transcriptional regulator PGC-1beta is associated with a selective reduction in Mitofusin 2 (Mfn2) expression, a mitochondrial fusion protein.This PGC-1beta-induced elongation specifically requires Mfn2 as this process is absent in Mfn2-ablated cells.Finally, we show that PGC-1beta increases Mfn2 promoter activity and transcription by coactivating the nuclear receptor Estrogen Related Receptor alpha (ERRalpha).

View Article: PubMed Central - PubMed

Affiliation: Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain.

ABSTRACT

Background: There is no evidence to date on whether transcriptional regulators are able to shift the balance between mitochondrial fusion and fission events through selective control of gene expression.

Methodology/principal findings: Here, we demonstrate that reduced mitochondrial size observed in knock-out mice for the transcriptional regulator PGC-1beta is associated with a selective reduction in Mitofusin 2 (Mfn2) expression, a mitochondrial fusion protein. This decrease in Mfn2 is specific since expression of the remaining components of mitochondrial fusion and fission machinery were not affected. Furthermore, PGC-1beta increases mitochondrial fusion and elongates mitochondrial tubules. This PGC-1beta-induced elongation specifically requires Mfn2 as this process is absent in Mfn2-ablated cells. Finally, we show that PGC-1beta increases Mfn2 promoter activity and transcription by coactivating the nuclear receptor Estrogen Related Receptor alpha (ERRalpha).

Conclusions/significance: Taken together, our data reveal a novel mechanism by which mammalian cells control mitochondrial fusion. In addition, we describe a novel role of PGC-1beta in mitochondrial physiology, namely the control of mitochondrial fusion mainly through Mfn2.

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Related in: MedlinePlus

Effect of PGC-1β on the expression of Mfn2, other proteins involved in mitochondrial dynamics, Porin and ETC subunits.Total lysates and mitochondrial fractions were obtained from C2C12 myotubes 48 h after adenoviral transduction, and the expression of proteins was analyzed by Western blot (40 µg). Representative films of a single experiment from four independent differentiation and transduction experiments are shown. (A) Total lysates and mitochondrial fractions of non-transduced myotubes (NT), transduced with LacZ or GFP control adenovirus at a MOI 100 (control adenovirus at a MOI 1 and 10 displayed no changes, data not shown) or with PGC-1β adenovirus at a MOI 1, 10 or 100 were probed with anti-Mfn2 and Porin antibodies. (B) Specific antibodies were used to detect mitochondrial dynamics proteins (Mfn1,OPA1, Drp1 and Fis1) and single subunits from each complex of the ETC (complex I, Ndufa9; complex II, Sdha; complex III, Uqcrc2; complex IV, Cox4 and complex V, ATP5a1) in mitochondrial fractions of non-transduced (NT) or transduced C2C12 myotubes at a MOI 100 with LacZ or PGC-1β adenovirus. (C) Quantification analysis of protein levels of mitochondrial dynamics components and the ETC subunits from complexes I to V detected by Western blot. Mean±SEM of Non- (white bars) , LacZ- (grey bars) or PGC-1β- (black bars) transduced C2C12 myotubes from n = 4 independent differentiation and transduction (MOI 100) experiments. *, statistical difference compared to LacZ transduction, p<0.05. #, statistical difference compared to Porin induction, p<0.05.
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pone-0003613-g002: Effect of PGC-1β on the expression of Mfn2, other proteins involved in mitochondrial dynamics, Porin and ETC subunits.Total lysates and mitochondrial fractions were obtained from C2C12 myotubes 48 h after adenoviral transduction, and the expression of proteins was analyzed by Western blot (40 µg). Representative films of a single experiment from four independent differentiation and transduction experiments are shown. (A) Total lysates and mitochondrial fractions of non-transduced myotubes (NT), transduced with LacZ or GFP control adenovirus at a MOI 100 (control adenovirus at a MOI 1 and 10 displayed no changes, data not shown) or with PGC-1β adenovirus at a MOI 1, 10 or 100 were probed with anti-Mfn2 and Porin antibodies. (B) Specific antibodies were used to detect mitochondrial dynamics proteins (Mfn1,OPA1, Drp1 and Fis1) and single subunits from each complex of the ETC (complex I, Ndufa9; complex II, Sdha; complex III, Uqcrc2; complex IV, Cox4 and complex V, ATP5a1) in mitochondrial fractions of non-transduced (NT) or transduced C2C12 myotubes at a MOI 100 with LacZ or PGC-1β adenovirus. (C) Quantification analysis of protein levels of mitochondrial dynamics components and the ETC subunits from complexes I to V detected by Western blot. Mean±SEM of Non- (white bars) , LacZ- (grey bars) or PGC-1β- (black bars) transduced C2C12 myotubes from n = 4 independent differentiation and transduction (MOI 100) experiments. *, statistical difference compared to LacZ transduction, p<0.05. #, statistical difference compared to Porin induction, p<0.05.

Mentions: To determine whether PGC-1β-mediated Mfn2 transcription leads to enhanced Mfn2 protein expression, we transduced C2C12 myotubes with PGC-1β or two distinct control adenoviruses at a multiplicity of infection (MOI) of 1, 10 or 100. Total protein extracts and mitochondrial-enriched fractions were obtained and analyzed by Western blot. PGC-1β induced Mfn2 in muscle cells (Fig. 2A) and a direct relationship between PGC-1β adenoviral dose and Mfn2 protein induction was detected (Fig. 2A). PGC-1β also increased the cellular content of the constitutive mitochondrial protein Porin (Fig. 2A), used as a measure of mitochondrial mass. Densitometric quantification of Porin induction at MOI 100 showed a 1.8±0.2-fold increase in total lysates (p = 0.01, Figure S2) and 1.45±0.003-fold in mitochondrial-enriched fractions (p = 0.002, Fig. 2C). Porin induction values in total lysates are consistent with the increase in mitochondrial mass volume reported in PGC-1β-overexpressing C2C12 muscle cells [18].


Mitochondrial fusion is increased by the nuclear coactivator PGC-1beta.

Liesa M, Borda-d'Agua B, Medina-Gómez G, Lelliott CJ, Paz JC, Rojo M, Palacín M, Vidal-Puig A, Zorzano A - PLoS ONE (2008)

Effect of PGC-1β on the expression of Mfn2, other proteins involved in mitochondrial dynamics, Porin and ETC subunits.Total lysates and mitochondrial fractions were obtained from C2C12 myotubes 48 h after adenoviral transduction, and the expression of proteins was analyzed by Western blot (40 µg). Representative films of a single experiment from four independent differentiation and transduction experiments are shown. (A) Total lysates and mitochondrial fractions of non-transduced myotubes (NT), transduced with LacZ or GFP control adenovirus at a MOI 100 (control adenovirus at a MOI 1 and 10 displayed no changes, data not shown) or with PGC-1β adenovirus at a MOI 1, 10 or 100 were probed with anti-Mfn2 and Porin antibodies. (B) Specific antibodies were used to detect mitochondrial dynamics proteins (Mfn1,OPA1, Drp1 and Fis1) and single subunits from each complex of the ETC (complex I, Ndufa9; complex II, Sdha; complex III, Uqcrc2; complex IV, Cox4 and complex V, ATP5a1) in mitochondrial fractions of non-transduced (NT) or transduced C2C12 myotubes at a MOI 100 with LacZ or PGC-1β adenovirus. (C) Quantification analysis of protein levels of mitochondrial dynamics components and the ETC subunits from complexes I to V detected by Western blot. Mean±SEM of Non- (white bars) , LacZ- (grey bars) or PGC-1β- (black bars) transduced C2C12 myotubes from n = 4 independent differentiation and transduction (MOI 100) experiments. *, statistical difference compared to LacZ transduction, p<0.05. #, statistical difference compared to Porin induction, p<0.05.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2570954&req=5

pone-0003613-g002: Effect of PGC-1β on the expression of Mfn2, other proteins involved in mitochondrial dynamics, Porin and ETC subunits.Total lysates and mitochondrial fractions were obtained from C2C12 myotubes 48 h after adenoviral transduction, and the expression of proteins was analyzed by Western blot (40 µg). Representative films of a single experiment from four independent differentiation and transduction experiments are shown. (A) Total lysates and mitochondrial fractions of non-transduced myotubes (NT), transduced with LacZ or GFP control adenovirus at a MOI 100 (control adenovirus at a MOI 1 and 10 displayed no changes, data not shown) or with PGC-1β adenovirus at a MOI 1, 10 or 100 were probed with anti-Mfn2 and Porin antibodies. (B) Specific antibodies were used to detect mitochondrial dynamics proteins (Mfn1,OPA1, Drp1 and Fis1) and single subunits from each complex of the ETC (complex I, Ndufa9; complex II, Sdha; complex III, Uqcrc2; complex IV, Cox4 and complex V, ATP5a1) in mitochondrial fractions of non-transduced (NT) or transduced C2C12 myotubes at a MOI 100 with LacZ or PGC-1β adenovirus. (C) Quantification analysis of protein levels of mitochondrial dynamics components and the ETC subunits from complexes I to V detected by Western blot. Mean±SEM of Non- (white bars) , LacZ- (grey bars) or PGC-1β- (black bars) transduced C2C12 myotubes from n = 4 independent differentiation and transduction (MOI 100) experiments. *, statistical difference compared to LacZ transduction, p<0.05. #, statistical difference compared to Porin induction, p<0.05.
Mentions: To determine whether PGC-1β-mediated Mfn2 transcription leads to enhanced Mfn2 protein expression, we transduced C2C12 myotubes with PGC-1β or two distinct control adenoviruses at a multiplicity of infection (MOI) of 1, 10 or 100. Total protein extracts and mitochondrial-enriched fractions were obtained and analyzed by Western blot. PGC-1β induced Mfn2 in muscle cells (Fig. 2A) and a direct relationship between PGC-1β adenoviral dose and Mfn2 protein induction was detected (Fig. 2A). PGC-1β also increased the cellular content of the constitutive mitochondrial protein Porin (Fig. 2A), used as a measure of mitochondrial mass. Densitometric quantification of Porin induction at MOI 100 showed a 1.8±0.2-fold increase in total lysates (p = 0.01, Figure S2) and 1.45±0.003-fold in mitochondrial-enriched fractions (p = 0.002, Fig. 2C). Porin induction values in total lysates are consistent with the increase in mitochondrial mass volume reported in PGC-1β-overexpressing C2C12 muscle cells [18].

Bottom Line: Here, we demonstrate that reduced mitochondrial size observed in knock-out mice for the transcriptional regulator PGC-1beta is associated with a selective reduction in Mitofusin 2 (Mfn2) expression, a mitochondrial fusion protein.This PGC-1beta-induced elongation specifically requires Mfn2 as this process is absent in Mfn2-ablated cells.Finally, we show that PGC-1beta increases Mfn2 promoter activity and transcription by coactivating the nuclear receptor Estrogen Related Receptor alpha (ERRalpha).

View Article: PubMed Central - PubMed

Affiliation: Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain.

ABSTRACT

Background: There is no evidence to date on whether transcriptional regulators are able to shift the balance between mitochondrial fusion and fission events through selective control of gene expression.

Methodology/principal findings: Here, we demonstrate that reduced mitochondrial size observed in knock-out mice for the transcriptional regulator PGC-1beta is associated with a selective reduction in Mitofusin 2 (Mfn2) expression, a mitochondrial fusion protein. This decrease in Mfn2 is specific since expression of the remaining components of mitochondrial fusion and fission machinery were not affected. Furthermore, PGC-1beta increases mitochondrial fusion and elongates mitochondrial tubules. This PGC-1beta-induced elongation specifically requires Mfn2 as this process is absent in Mfn2-ablated cells. Finally, we show that PGC-1beta increases Mfn2 promoter activity and transcription by coactivating the nuclear receptor Estrogen Related Receptor alpha (ERRalpha).

Conclusions/significance: Taken together, our data reveal a novel mechanism by which mammalian cells control mitochondrial fusion. In addition, we describe a novel role of PGC-1beta in mitochondrial physiology, namely the control of mitochondrial fusion mainly through Mfn2.

Show MeSH
Related in: MedlinePlus