Intermittent hypoxia activates peptidylglycine α-amidating monooxygenase in rat brain stem via reactive oxygen species-mediated proteolytic processing

Suresh D. Sharma, Gayatri Raghuraman, Myeong Seon Lee, Nanduri R. Prabhakar, Ganesh K. Kumar

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Intermittent hypoxia (IH) associated with sleep apneas leads to cardiorespiratory abnormalities that may involve altered neuropeptide signaling. The effects of IH on neuropeptide synthesis have not been investigated. Peptidylglycine α-amidating monooxygenase (PAM; EC 1.14.17.3) catalyzes the α-amidation of neuropeptides, which confers biological activity to a large number of neuropeptides. PAM consists of O 2-sensitive peptidylglycine α-hydroxylating monooxygenase (PHM) and pepti-dyl-α-hydroxyglycine α-amidating lyase (PAL) activities. Here, we examined whether IH alters neuropeptide synthesis by affecting PAM activity and, if so, by what mechanisms. Experiments were performed on the brain stem of adult male rats exposed to IH (5% O 2 for 15 s followed by 21% O 2 for 5 min; 8 h/day for up to 10 days) or continuous hypoxia (0.4 atm for 10 days). Analysis of brain stem extracts showed that IH, but not continuous hypoxia, increased PHM, but not PAL, activity of PAM and that the increase of PHM activity was associated with a concomitant elevation in the levels of α-ami-dated forms of substance P and neuropeptide Y. IH increased the relative abundance of 42- and 35-kDa forms of PHM (∼1.6- and 2.7-fold, respectively), suggesting enhanced proteolytic processing of PHM, which appears to be mediated by an IH-induced increase of endoprotease activity. Kinetic analysis showed that IH increases V max but has no effect on K m. IH increased generation of reactive oxygen species in the brain stem, and systemic administration of antioxidant prevented IH-evoked increases of PHM activity, proteolytic processing of PHM, endoprotease activity, and elevations in substance P and neuropeptide Y amide levels. Taken together, these results demonstrate that IH activates PHM in rat brain stem via reactive oxygen species-dependent posttranslational proteolytic processing and further suggest that PAM activation may contribute to IH-mediated peptidergic neurotransmission in rat brain stem.

Original languageEnglish (US)
Pages (from-to)12-19
Number of pages8
JournalJournal of applied physiology
Volume106
Issue number1
DOIs
StatePublished - Jan 1 2009

Fingerprint

Brain Stem
Reactive Oxygen Species
Neuropeptides
Lyases
Neuropeptide Y
Substance P
peptidylglycine monooxygenase
Hypoxia
Sleep Apnea Syndromes
Amides
Synaptic Transmission
Antioxidants

All Science Journal Classification (ASJC) codes

  • Physiology
  • Physiology (medical)

Cite this

Sharma, Suresh D. ; Raghuraman, Gayatri ; Lee, Myeong Seon ; Prabhakar, Nanduri R. ; Kumar, Ganesh K. / Intermittent hypoxia activates peptidylglycine α-amidating monooxygenase in rat brain stem via reactive oxygen species-mediated proteolytic processing. In: Journal of applied physiology. 2009 ; Vol. 106, No. 1. pp. 12-19.
@article{50e130fc55044fb69ac896df2376fe7c,
title = "Intermittent hypoxia activates peptidylglycine α-amidating monooxygenase in rat brain stem via reactive oxygen species-mediated proteolytic processing",
abstract = "Intermittent hypoxia (IH) associated with sleep apneas leads to cardiorespiratory abnormalities that may involve altered neuropeptide signaling. The effects of IH on neuropeptide synthesis have not been investigated. Peptidylglycine α-amidating monooxygenase (PAM; EC 1.14.17.3) catalyzes the α-amidation of neuropeptides, which confers biological activity to a large number of neuropeptides. PAM consists of O 2-sensitive peptidylglycine α-hydroxylating monooxygenase (PHM) and pepti-dyl-α-hydroxyglycine α-amidating lyase (PAL) activities. Here, we examined whether IH alters neuropeptide synthesis by affecting PAM activity and, if so, by what mechanisms. Experiments were performed on the brain stem of adult male rats exposed to IH (5{\%} O 2 for 15 s followed by 21{\%} O 2 for 5 min; 8 h/day for up to 10 days) or continuous hypoxia (0.4 atm for 10 days). Analysis of brain stem extracts showed that IH, but not continuous hypoxia, increased PHM, but not PAL, activity of PAM and that the increase of PHM activity was associated with a concomitant elevation in the levels of α-ami-dated forms of substance P and neuropeptide Y. IH increased the relative abundance of 42- and 35-kDa forms of PHM (∼1.6- and 2.7-fold, respectively), suggesting enhanced proteolytic processing of PHM, which appears to be mediated by an IH-induced increase of endoprotease activity. Kinetic analysis showed that IH increases V max but has no effect on K m. IH increased generation of reactive oxygen species in the brain stem, and systemic administration of antioxidant prevented IH-evoked increases of PHM activity, proteolytic processing of PHM, endoprotease activity, and elevations in substance P and neuropeptide Y amide levels. Taken together, these results demonstrate that IH activates PHM in rat brain stem via reactive oxygen species-dependent posttranslational proteolytic processing and further suggest that PAM activation may contribute to IH-mediated peptidergic neurotransmission in rat brain stem.",
author = "Sharma, {Suresh D.} and Gayatri Raghuraman and Lee, {Myeong Seon} and Prabhakar, {Nanduri R.} and Kumar, {Ganesh K.}",
year = "2009",
month = "1",
day = "1",
doi = "10.1152/japplphysiol.90702.2008",
language = "English (US)",
volume = "106",
pages = "12--19",
journal = "Journal of Applied Physiology",
issn = "8750-7587",
publisher = "American Physiological Society",
number = "1",

}

Intermittent hypoxia activates peptidylglycine α-amidating monooxygenase in rat brain stem via reactive oxygen species-mediated proteolytic processing. / Sharma, Suresh D.; Raghuraman, Gayatri; Lee, Myeong Seon; Prabhakar, Nanduri R.; Kumar, Ganesh K.

In: Journal of applied physiology, Vol. 106, No. 1, 01.01.2009, p. 12-19.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Intermittent hypoxia activates peptidylglycine α-amidating monooxygenase in rat brain stem via reactive oxygen species-mediated proteolytic processing

AU - Sharma, Suresh D.

AU - Raghuraman, Gayatri

AU - Lee, Myeong Seon

AU - Prabhakar, Nanduri R.

AU - Kumar, Ganesh K.

PY - 2009/1/1

Y1 - 2009/1/1

N2 - Intermittent hypoxia (IH) associated with sleep apneas leads to cardiorespiratory abnormalities that may involve altered neuropeptide signaling. The effects of IH on neuropeptide synthesis have not been investigated. Peptidylglycine α-amidating monooxygenase (PAM; EC 1.14.17.3) catalyzes the α-amidation of neuropeptides, which confers biological activity to a large number of neuropeptides. PAM consists of O 2-sensitive peptidylglycine α-hydroxylating monooxygenase (PHM) and pepti-dyl-α-hydroxyglycine α-amidating lyase (PAL) activities. Here, we examined whether IH alters neuropeptide synthesis by affecting PAM activity and, if so, by what mechanisms. Experiments were performed on the brain stem of adult male rats exposed to IH (5% O 2 for 15 s followed by 21% O 2 for 5 min; 8 h/day for up to 10 days) or continuous hypoxia (0.4 atm for 10 days). Analysis of brain stem extracts showed that IH, but not continuous hypoxia, increased PHM, but not PAL, activity of PAM and that the increase of PHM activity was associated with a concomitant elevation in the levels of α-ami-dated forms of substance P and neuropeptide Y. IH increased the relative abundance of 42- and 35-kDa forms of PHM (∼1.6- and 2.7-fold, respectively), suggesting enhanced proteolytic processing of PHM, which appears to be mediated by an IH-induced increase of endoprotease activity. Kinetic analysis showed that IH increases V max but has no effect on K m. IH increased generation of reactive oxygen species in the brain stem, and systemic administration of antioxidant prevented IH-evoked increases of PHM activity, proteolytic processing of PHM, endoprotease activity, and elevations in substance P and neuropeptide Y amide levels. Taken together, these results demonstrate that IH activates PHM in rat brain stem via reactive oxygen species-dependent posttranslational proteolytic processing and further suggest that PAM activation may contribute to IH-mediated peptidergic neurotransmission in rat brain stem.

AB - Intermittent hypoxia (IH) associated with sleep apneas leads to cardiorespiratory abnormalities that may involve altered neuropeptide signaling. The effects of IH on neuropeptide synthesis have not been investigated. Peptidylglycine α-amidating monooxygenase (PAM; EC 1.14.17.3) catalyzes the α-amidation of neuropeptides, which confers biological activity to a large number of neuropeptides. PAM consists of O 2-sensitive peptidylglycine α-hydroxylating monooxygenase (PHM) and pepti-dyl-α-hydroxyglycine α-amidating lyase (PAL) activities. Here, we examined whether IH alters neuropeptide synthesis by affecting PAM activity and, if so, by what mechanisms. Experiments were performed on the brain stem of adult male rats exposed to IH (5% O 2 for 15 s followed by 21% O 2 for 5 min; 8 h/day for up to 10 days) or continuous hypoxia (0.4 atm for 10 days). Analysis of brain stem extracts showed that IH, but not continuous hypoxia, increased PHM, but not PAL, activity of PAM and that the increase of PHM activity was associated with a concomitant elevation in the levels of α-ami-dated forms of substance P and neuropeptide Y. IH increased the relative abundance of 42- and 35-kDa forms of PHM (∼1.6- and 2.7-fold, respectively), suggesting enhanced proteolytic processing of PHM, which appears to be mediated by an IH-induced increase of endoprotease activity. Kinetic analysis showed that IH increases V max but has no effect on K m. IH increased generation of reactive oxygen species in the brain stem, and systemic administration of antioxidant prevented IH-evoked increases of PHM activity, proteolytic processing of PHM, endoprotease activity, and elevations in substance P and neuropeptide Y amide levels. Taken together, these results demonstrate that IH activates PHM in rat brain stem via reactive oxygen species-dependent posttranslational proteolytic processing and further suggest that PAM activation may contribute to IH-mediated peptidergic neurotransmission in rat brain stem.

UR - http://www.scopus.com/inward/record.url?scp=58649093541&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=58649093541&partnerID=8YFLogxK

U2 - 10.1152/japplphysiol.90702.2008

DO - 10.1152/japplphysiol.90702.2008

M3 - Article

C2 - 18818385

AN - SCOPUS:58649093541

VL - 106

SP - 12

EP - 19

JO - Journal of Applied Physiology

JF - Journal of Applied Physiology

SN - 8750-7587

IS - 1

ER -