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Heat shock protein 22 (Hsp22) regulates oxidative phosphorylation upon its mitochondrial translocation with the inducible nitric oxide synthase in mammalian heart.

Rashed E, Lizano P, Dai H, Thomas A, Suzuki CK, Depre C, Qiu H - PLoS ONE (2015)

Bottom Line: Hsp22 overexpression in vivo stimulates cardiac mitochondrial respiration, whereas Hsp22 deletion in vivo significantly reduces respiration.Upon comparable overexpression, the N20-Hsp22 mutant did not show significant mitochondrial translocation or stimulation of mitochondrial respiration.Moreover, although N20-Hsp22 did increase global iNOS expression by 4.6-fold, it did not promote iNOS mitochondrial translocation.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States of America.

ABSTRACT

Objectives: Stress-inducible heat shock protein 22 (Hsp22) confers protection against ischemia through induction of the inducible isoform of nitric oxide synthase (iNOS). Hsp22 overexpression in vivo stimulates cardiac mitochondrial respiration, whereas Hsp22 deletion in vivo significantly reduces respiration. We hypothesized that Hsp22-mediated regulation of mitochondrial function is dependent upon its mitochondrial translocation together with iNOS.

Methods and results: Adenoviruses harboring either the full coding sequence of Hsp22 (Ad-WT-Hsp22) or a mutant lacking a N-terminal 20 amino acid putative mitochondrial localization sequence (Ad-N20-Hsp22) were generated, and infected in rat neonatal cardiomyocytes. Compared to β-Gal control, WT-Hsp22 accumulated in mitochondria by 2.5 fold (P<0.05) and increased oxygen consumption rates by 2-fold (P<0.01). This latter effect was abolished upon addition of the selective iNOS inhibitor, 1400 W. Ad-WT-Hsp22 significantly increased global iNOS expression by about 2.5-fold (P<0.01), and also increased iNOS mitochondrial localization by 4.5 fold vs. β-gal (P<0.05). Upon comparable overexpression, the N20-Hsp22 mutant did not show significant mitochondrial translocation or stimulation of mitochondrial respiration. Moreover, although N20-Hsp22 did increase global iNOS expression by 4.6-fold, it did not promote iNOS mitochondrial translocation.

Conclusion: Translocation of both Hsp22 and iNOS to the mitochondria is necessary for Hsp22-mediated stimulation of oxidative phosphorylation.

No MeSH data available.


Related in: MedlinePlus

Regulation of gene expression of Hsp22 mutant proteins in cardiac myocytes.Immunoblotting of P-STAT3 (Y705) in myocytes treated with the β-Gal, WT-Hsp22 or N20-Hsp22 adenoviruses (20 moi). * P<0.05 vs β-Gal, n = 6 per group.
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pone.0119537.g003: Regulation of gene expression of Hsp22 mutant proteins in cardiac myocytes.Immunoblotting of P-STAT3 (Y705) in myocytes treated with the β-Gal, WT-Hsp22 or N20-Hsp22 adenoviruses (20 moi). * P<0.05 vs β-Gal, n = 6 per group.

Mentions: We showed before that Hsp22 over-expression regulates gene expression through the regulation of specific transcription factors, including STAT3 [10]. Therefore, we investigated whether the N-terminal mutant Hsp22 protein preserved its biological function on transcriptional regulation. Ad-WT-Hsp22 and Ad-N20-Hsp22 were infected at 20 moi in RNCMs. Y705 phosphorylation of the transcription factor STAT3, a target through which Hsp22 affects gene expression [10], was used as a control to show the activation of the STAT3 protein. As shown in Fig. 3, upon a comparable amount of Hsp22 overexpression, myocytes infected with either Ad-WT-Hsp22 or Ad-N20-Hsp22 exhibited increased Y705 phosphorylation of STAT3 by about 3.0 fold vs β-Gal control (P<0.05). Therefore, the truncated Hsp22 protein retains its native function and activity on transcriptional regulation.


Heat shock protein 22 (Hsp22) regulates oxidative phosphorylation upon its mitochondrial translocation with the inducible nitric oxide synthase in mammalian heart.

Rashed E, Lizano P, Dai H, Thomas A, Suzuki CK, Depre C, Qiu H - PLoS ONE (2015)

Regulation of gene expression of Hsp22 mutant proteins in cardiac myocytes.Immunoblotting of P-STAT3 (Y705) in myocytes treated with the β-Gal, WT-Hsp22 or N20-Hsp22 adenoviruses (20 moi). * P<0.05 vs β-Gal, n = 6 per group.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4352051&req=5

pone.0119537.g003: Regulation of gene expression of Hsp22 mutant proteins in cardiac myocytes.Immunoblotting of P-STAT3 (Y705) in myocytes treated with the β-Gal, WT-Hsp22 or N20-Hsp22 adenoviruses (20 moi). * P<0.05 vs β-Gal, n = 6 per group.
Mentions: We showed before that Hsp22 over-expression regulates gene expression through the regulation of specific transcription factors, including STAT3 [10]. Therefore, we investigated whether the N-terminal mutant Hsp22 protein preserved its biological function on transcriptional regulation. Ad-WT-Hsp22 and Ad-N20-Hsp22 were infected at 20 moi in RNCMs. Y705 phosphorylation of the transcription factor STAT3, a target through which Hsp22 affects gene expression [10], was used as a control to show the activation of the STAT3 protein. As shown in Fig. 3, upon a comparable amount of Hsp22 overexpression, myocytes infected with either Ad-WT-Hsp22 or Ad-N20-Hsp22 exhibited increased Y705 phosphorylation of STAT3 by about 3.0 fold vs β-Gal control (P<0.05). Therefore, the truncated Hsp22 protein retains its native function and activity on transcriptional regulation.

Bottom Line: Hsp22 overexpression in vivo stimulates cardiac mitochondrial respiration, whereas Hsp22 deletion in vivo significantly reduces respiration.Upon comparable overexpression, the N20-Hsp22 mutant did not show significant mitochondrial translocation or stimulation of mitochondrial respiration.Moreover, although N20-Hsp22 did increase global iNOS expression by 4.6-fold, it did not promote iNOS mitochondrial translocation.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States of America.

ABSTRACT

Objectives: Stress-inducible heat shock protein 22 (Hsp22) confers protection against ischemia through induction of the inducible isoform of nitric oxide synthase (iNOS). Hsp22 overexpression in vivo stimulates cardiac mitochondrial respiration, whereas Hsp22 deletion in vivo significantly reduces respiration. We hypothesized that Hsp22-mediated regulation of mitochondrial function is dependent upon its mitochondrial translocation together with iNOS.

Methods and results: Adenoviruses harboring either the full coding sequence of Hsp22 (Ad-WT-Hsp22) or a mutant lacking a N-terminal 20 amino acid putative mitochondrial localization sequence (Ad-N20-Hsp22) were generated, and infected in rat neonatal cardiomyocytes. Compared to β-Gal control, WT-Hsp22 accumulated in mitochondria by 2.5 fold (P<0.05) and increased oxygen consumption rates by 2-fold (P<0.01). This latter effect was abolished upon addition of the selective iNOS inhibitor, 1400 W. Ad-WT-Hsp22 significantly increased global iNOS expression by about 2.5-fold (P<0.01), and also increased iNOS mitochondrial localization by 4.5 fold vs. β-gal (P<0.05). Upon comparable overexpression, the N20-Hsp22 mutant did not show significant mitochondrial translocation or stimulation of mitochondrial respiration. Moreover, although N20-Hsp22 did increase global iNOS expression by 4.6-fold, it did not promote iNOS mitochondrial translocation.

Conclusion: Translocation of both Hsp22 and iNOS to the mitochondria is necessary for Hsp22-mediated stimulation of oxidative phosphorylation.

No MeSH data available.


Related in: MedlinePlus