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Diaphragm unloading via controlled mechanical ventilation alters the gene expression profile.

ABSTRACT: Prolonged controlled mechanical ventilation results in diaphragmatic inactivity and promotes oxidative injury, atrophy, and contractile dysfunction in this important inspiratory muscle. However, the impact of controlled mechanical ventilation on global mRNA alterations in the diaphragm remains unknown.In these experiments, we used an Affymetrix oligonucleotide array to identify the temporal changes in diaphragmatic gene expression during controlled mechanical ventilation in the rat.Adult Sprague-Dawley rats were assigned to either control or mechanical ventilation groups (n = 5/group). Mechanically ventilated animals were anesthetized, tracheostomized, and ventilated with room air for 6 or 18 h. Animals in the control group were acutely anesthetized but not exposed to mechanical ventilation.Compared with control diaphragms, microarray analysis identified 354 differentially expressed, unique gene products after 6 and 18 h of mechanical ventilation. In general, genes in the cell growth/cell maintenance, stress response, and nucleic acid metabolism categories showed predominant upregulation, whereas genes in the structural protein and energy metabolism categories were predominantly downregulated.We conclude that mechanical ventilation results in rapid changes in diaphragmatic gene expression, and subsequently, many of these changes may contribute to atrophy and muscle fiber remodeling associated with unloading this primary inspiratory muscle. Importantly, this study also provides new insights into why the diaphragm, after the onset of contractile inactivity, atrophies more rapidly than locomotor skeletal muscles and also highlights unique differences that exist between these muscles in the mRNA response to inactivity.

SUBMITTER: DeRuisseau KC

PROVIDER: S-EPMC2718415 | biostudies-literature | 2005 Nov

REPOSITORIES: biostudies-literature

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Diaphragm unloading via controlled mechanical ventilation alters the gene expression profile.

DeRuisseau Keith C KC Shanely R Andrew RA Akunuri Nagabhavani N Hamilton Marc T MT Van Gammeren Darin D Zergeroglu A Murat AM McKenzie Michael M Powers Scott K SK

American journal of respiratory and critical care medicine 20050826 10

<h4>Rationale</h4>Prolonged controlled mechanical ventilation results in diaphragmatic inactivity and promotes oxidative injury, atrophy, and contractile dysfunction in this important inspiratory muscle. However, the impact of controlled mechanical ventilation on global mRNA alterations in the diaphragm remains unknown.<h4>Objectives</h4>In these experiments, we used an Affymetrix oligonucleotide array to identify the temporal changes in diaphragmatic gene expression during controlled mechanical ...[more]

PMID: 16126937

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Project description:Controlled mechanical ventilation (CMV) is associated with the development of diaphragm atrophy and contractile dysfunction, and respiratory muscle weakness is thought to contribute significantly to delayed weaning of patients. Therefore, therapeutic strategies for preventing these processes may have clinical benefit. The aim of the current study was to investigate the role of the Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) signaling pathway in CMV-mediated diaphragm wasting and weakness in rats. CMV-induced diaphragm atrophy and contractile dysfunction coincided with marked increases in STAT3 phosphorylation on both tyrosine 705 (Tyr705) and serine 727 (Ser727). STAT3 activation was accompanied by its translocation into mitochondria within diaphragm muscle and mitochondrial dysfunction. Inhibition of JAK signaling during CMV prevented phosphorylation of both target sites on STAT3, eliminated the accumulation of phosphorylated STAT3 within the mitochondria, and reversed the pathologic alterations in mitochondrial function, reduced oxidative stress in the diaphragm, and maintained normal diaphragm contractility. In addition, JAK inhibition during CMV blunted the activation of key proteolytic pathways in the diaphragm, as well as diaphragm atrophy. These findings implicate JAK/STAT3 signaling in the development of diaphragm muscle atrophy and dysfunction during CMV and suggest that the delayed extubation times associated with CMV can be prevented by inhibition of Janus kinase signaling.-Smith, I. J., Godinez, G. L., Singh, B. K., McCaughey, K. M., Alcantara, R. R., Gururaja, T., Ho, M. S., Nguyen, H. N., Friera, A. M., White, K. A., McLaughlin, J. R., Hansen, D., Romero, J. M., Baltgalvis, K. A., Claypool, M. D., Li, W., Lang, W., Yam, G. C., Gelman, M. S., Ding, R., Yung, S. L., Creger, D. P., Chen, Y., Singh, R., Smuder, A. J., Wiggs, M. P., Kwon, O.-S., Sollanek, K. J., Powers, S. K., Masuda, E. S., Taylor, V. C., Payan, D. G., Kinoshita, T., Kinsella, T. M. Inhibition of Janus kinase signaling during controlled mechanical ventilation prevents ventilation-induced diaphragm dysfunction.

Project description:Previous workers have demonstrated that controlled mechanical ventilation results in diaphragm inactivity and elicits a rapid development of diaphragm weakness as a result of both contractile dysfunction and fiber atrophy. Limited data exist regarding the impact of pressure support ventilation, a commonly used mode of mechanical ventilation-that permits partial mechanical activity of the diaphragm-on diaphragm structure and function. We carried out the present study to test the hypothesis that high-level pressure support ventilation decreases the diaphragm pathology associated with CMV.Sprague-Dawley rats were randomly assigned to one of the following five groups:1) control (no mechanical ventilation); 2) 12 hrs of controlled mechanical ventilation (12CMV); 3) 18 hrs of controlled mechanical ventilation (18CMV); 4) 12 hrs of pressure support ventilation (12PSV); or 5) 18 hrs of pressure support ventilation (18PSV).We carried out the following measurements on diaphragm specimens: 4-hydroxynonenal-a marker of oxidative stress, active caspase-3 (casp-3), active calpain-1 (calp-1), fiber type cross-sectional area, and specific force (sp F). Compared with the control, both 12PSV and 18PSV promoted a significant decrement in diaphragmatic specific force production, but to a lesser degree than 12CMV and 18CMV. Furthermore, 12CMV, 18PSV, and 18CMV resulted in significant atrophy in all diaphragm fiber types as well as significant increases in a biomarker of oxidative stress (4-hydroxynonenal) and increased proteolytic activity (20S proteasome, calpain-1, and caspase-3). Furthermore, although no inspiratory effort occurs during controlled mechanical ventilation, it was observed that pressure support ventilation resulted in large decrement, approximately 96%, in inspiratory effort compared with spontaneously breathing animals.High levels of prolonged pressure support ventilation promote diaphragmatic atrophy and contractile dysfunction. Furthermore, similar to controlled mechanical ventilation, pressure support ventilation-induced diaphragmatic atrophy and weakness are associated with both diaphragmatic oxidative stress and protease activation.

Project description:SUMOylation is a key post-translational modification that regulates crucial cellular functions and pathological processes. It has emerged as a fundamental route that may drive different steps of human diseases. Indeed, alteration in expression or activity of one of the different SUMO pathway components may completely subvert cellular properties through fine-tuning modulation of protein(s) involved in cellular/tissue pathways, leading to alter cell proliferation, tissue regeneration, apoptosis resistance and metastatic potential. What is SUMOylation? SUMO, the Small Ubiquitin-like Modifier is a 97-amino acid protein that can be covalently attached to lysine residues on target proteins via an enzymatic cascade reaction named SUMOylation. SUMOylation requires an E1 (hetero-dimer SUMO-activating, SAE1/2), E2 (SUMO-specific conjugating, Ubc9), and, in most cases, E3 (SUMO ligase, PIASs) enzymes. There are four reported SUMO paralogues, SUMO-1 to SUMO-4, present in mammalian. All SUMO paralogues are transiently and reversibly conjugated to substrate proteins by the same enzymatic machinery but they can modify distinct targets although some proteins can be SUMOylated by either SUMO-1 or SUMO-2/3. The modifiers are expressed as immature peptides that must be cleaved prior to conjugation. This is carried out by isopeptidases, known as SENPs or SUMO specific proteases. The cleavage generates a C-terminal carboxyl group, SUMO-Gly-Gly, that will be attached via an isopeptide bond, formed between the epsilon-amino group of a Lys residue in the consensus sequence in target proteins designated ΨKxD/E, where Ψ is a large hydrophobic residue, K is the target lysine (Lys) and D/E are acidic residues. SUMO-2 and -3 have the ability to form poly-SUMO chains by covalent linkage of the C-terminal Gly-Gly residue to the internal Lys residue of their N-terminal consensus sequence motif. SUMO-1 lacks this consensus site and is unable to form chains but may act as a polySUMO chain terminator. SUMO-4 remains enigmatic since it has a restricted tissue distribution and may be unable to SUMOylate substrate proteins due to a proline residue that appears to prevent its maturation and conjugation. Heterodimeric activating enzyme E1 triggers SUMO proteins in an ATP-dependent way and transfers activated SUMO to a conserved catalytic cysteine in the conjugation enzyme E2. Ubc9, the only E2 identified delivers SUMO protein directly to the substrates. Ubc9 alone is sufficient for conjugation and ligation of the SUMO moiety to the substrates. However, the presence of SUMOylation E3 ligases, including the PIAS family, RanBP2, Polycomb2, TOPORS, TRAF7 and mitochondrial-anchored protein ligase (MPAL), stimulates the conjugation efficiency by promoting poly-SUMO chain formation and/or introducing additional SUMO acceptor sites. Despite being a covalent protein modification, SUMOylation is readily reversible due to the protease activity of SUMO specific deSUMOylation enzymes, SENPs. These enzymes exhibit specifically between the SUMO paralogues and have distinct subnuclear and subcellular localization patterns. Seven isoforms are known, including SENP1, SENP2, SENP3, SENP6 and SENP7. The SENPs contain distinct N-terminal domains that regulate their cellular localization, suggesting that each SENP may have a distinct set of substrates. In the last decade, the PTM with SUMO has emerged as a central regulatory mechanism for the control of cellular functions, including developmental and differentiation processes. However most of the studies have been performed on single eukaryotic cells from yeast to primary and model cells. The involvement of SUMOylation processes in regulating activity, function development and/or disorder in a more complex system like differentiated tissues (i.e: brain and cardiac muscle) is just emerging. At present, there is a completely lack of information regarding the functional significance of SUMOylation in skeletal muscle differentiation, regulation and diseases. Using a unique experimental Intensive Care Unit (ICU) rat model allowing long-term MV, diaphragm muscles were collected in rats control and exposed to controlled MV (CMV) for durations varying between 1 and 10 days. Endogenous SUMOylated diaphragm proteins were identified by mass-spectrometry and validated with in-vitro SUMOylation systems. Contractile, calcium regulator and mitochondrial proteins were of specific interest due to their putative involvement in VIDD. Differences were observed in the abundance of SUMOylated proteins between glycolytic and oxidative muscle fibers in control animals and high levels of SUMOylated proteins were present in all fibers during CMV. Finally, previously reported VIDD biomarkers and therapeutic targets were also identified in our datasets which may play an important role in response to muscle weakness seen in ICU patients.

Project description:BackgroundMechanical ventilation is a life-saving intervention used to provide adequate pulmonary ventilation in patients suffering from respiratory failure. However, prolonged mechanical ventilation is associated with significant diaphragmatic weakness resulting from both myofiber atrophy and contractile dysfunction. Although several signaling pathways contribute to diaphragm weakness during mechanical ventilation, it is established that oxidative stress is required for diaphragmatic weakness to occur. Therefore, identifying the site(s) of mechanical ventilation- induced reactive oxygen species production in the diaphragm is important.ObjectiveThese experiments tested the hypothesis that elevated mitochondrial reactive oxygen species emission is required for mechanical ventilation-induced oxidative stress, atrophy, and contractile dysfunction in the diaphragm.DesignCause and effect was determined by preventing mechanical ventilation-induced mitochondrial reactive oxygen species emission in the diaphragm of rats using a novel mitochondria-targeted antioxidant (SS-31).InterventionsNone.Measurements and main resultsCompared to mechanically ventilated animals treated with saline, animals treated with SS-31 were protected against mechanical ventilation-induced mitochondrial dysfunction, oxidative stress, and protease activation in the diaphragm. Importantly, treatment of animals with the mitochondrial antioxidant also protected the diaphragm against mechanical ventilation-induced myofiber atrophy and contractile dysfunction.ConclusionsThese results reveal that prevention of mechanical ventilation-induced increases in diaphragmatic mitochondrial reactive oxygen species emission protects the diaphragm from mechanical ventilation-induced diaphragmatic weakness. This important new finding indicates that mitochondria are a primary source of reactive oxygen species production in the diaphragm during prolonged mechanical ventilation. These results could lead to the development of a therapeutic intervention to impede mechanical ventilation-induced diaphragmatic weakness.

Project description:ObjectivesAlthough mechanical ventilation is a life-saving measure for patients in respiratory failure, prolonged mechanical ventilation results in diaphragmatic weakness attributable to fiber atrophy and contractile dysfunction. Therefore, identifying the signaling pathways responsible for mechanical ventilation-induced diaphragmatic weakness is important. In this context, it is established that oxidative stress is required for mechanical ventilation-induced diaphragmatic weakness to occur. Numerous redox-sensitive signaling pathways exist in muscle including the transcription factor nuclear factor-κB. Although it has been suggested that nuclear factor-κB contributes to proteolytic signaling in inactivity-induced atrophy in locomotor muscles, the role that nuclear factor-κB plays in mechanical ventilation-induced diaphragmatic weakness is unknown. We tested the hypothesis that nuclear factor-κB activation plays a key signaling role in mechanical ventilation-induced diaphragmatic weakness and that oxidative stress is required for nuclear factor-κB activation.DesignCause and effect was determined by independently treating mechanically ventilated animals with either a specific nuclear factor-κB inhibitor (SN50) or a clinically relevant antioxidant (curcumin).Measurements and main resultsInhibition of nuclear factor-κB activity partially attenuated both mechanical ventilation-induced diaphragmatic atrophy and contractile dysfunction. Further, treatment with the antioxidant curcumin prevented mechanical ventilation-induced activation of nuclear factor-κB in the diaphragm and rescued the diaphragm from both mechanical ventilation-induced atrophy and contractile dysfunction.ConclusionsCollectively, these findings support the hypothesis that nuclear factor-κB activation plays a significant signaling role in mechanical ventilation-induced diaphragmatic weakness and that oxidative stress is an upstream activator of nuclear factor-κB. Finally, our results suggest that prevention of mechanical ventilation-induced oxidative stress in the diaphragm could be a useful clinical strategy to prevent or delay mechanical ventilation-induced diaphragmatic weakness.

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Diaphragm unloading via controlled mechanical ventilation alters the gene expression profile.

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Diaphragm unloading via controlled mechanical ventilation alters the gene expression profile.

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