Inactivation of brain mitochondrial Lon protease by peroxynitrite precedes electron transport chain dysfunction.

Lee Stanyer; Wenche Jørgensen; Osamu Hori; John B Clark; Simon J R Heales

doi:10.1016/j.neuint.2008.06.004

Inactivation of brain mitochondrial Lon protease by peroxynitrite precedes electron transport chain dysfunction.

Lee Stanyer, Wenche Jørgensen, Osamu Hori, John B Clark, Simon J R Heales

Inflammation, Metabolism and Oxidation

40 Citations (Scopus)

Abstract

The accumulation of oxidatively modified proteins has been shown to be a characteristic feature of many neurodegenerative disorders and its regulation requires efficient proteolytic processing. One component of the mitochondrial proteolytic system is Lon, an ATP-dependent protease that has been shown to degrade oxidatively modified aconitase in vitro and may thus play a role in defending against the accumulation of oxidized matrix proteins in mitochondria. Using an assay system that allowed us to distinguish between basal and ATP-stimulated Lon protease activity, we have shown in isolated non-synaptic rat brain mitochondria that Lon protease is highly susceptible to oxidative inactivation by peroxynitrite (ONOO(-)). This susceptibility was more pronounced with regard to ATP-stimulated activity, which was inhibited by 75% in the presence of a bolus addition of 1mM ONOO(-), whereas basal unstimulated activity was inhibited by 45%. Treatment of mitochondria with a range of peroxynitrite concentrations (10-1000 microM) revealed that a decline in Lon protease activity preceded electron transport chain (ETC) dysfunction (complex I, II-III and IV) and that ATP-stimulated activity was approximately fivefold more sensitive than basal Lon protease activity. Furthermore, supplementation of mitochondrial matrix extracts with reduced glutathione, following ONOO(-) exposure, resulted in partial restoration of basal and ATP-stimulated activity, thus suggesting possible redox regulation of this enzyme complex. Taken together these findings suggest that Lon protease may be particularly vulnerable to inactivation in conditions associated with GSH depletion and elevated oxidative stress.

Original language	English
Journal	Neurochemistry International
Volume	53
Issue number	3-4
Pages (from-to)	95-101
Number of pages	6
ISSN	0197-0186
DOIs	https://doi.org/10.1016/j.neuint.2008.06.004
Publication status	Published - 2008

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title = "Inactivation of brain mitochondrial Lon protease by peroxynitrite precedes electron transport chain dysfunction.",

abstract = "The accumulation of oxidatively modified proteins has been shown to be a characteristic feature of many neurodegenerative disorders and its regulation requires efficient proteolytic processing. One component of the mitochondrial proteolytic system is Lon, an ATP-dependent protease that has been shown to degrade oxidatively modified aconitase in vitro and may thus play a role in defending against the accumulation of oxidized matrix proteins in mitochondria. Using an assay system that allowed us to distinguish between basal and ATP-stimulated Lon protease activity, we have shown in isolated non-synaptic rat brain mitochondria that Lon protease is highly susceptible to oxidative inactivation by peroxynitrite (ONOO(-)). This susceptibility was more pronounced with regard to ATP-stimulated activity, which was inhibited by 75% in the presence of a bolus addition of 1mM ONOO(-), whereas basal unstimulated activity was inhibited by 45%. Treatment of mitochondria with a range of peroxynitrite concentrations (10-1000 microM) revealed that a decline in Lon protease activity preceded electron transport chain (ETC) dysfunction (complex I, II-III and IV) and that ATP-stimulated activity was approximately fivefold more sensitive than basal Lon protease activity. Furthermore, supplementation of mitochondrial matrix extracts with reduced glutathione, following ONOO(-) exposure, resulted in partial restoration of basal and ATP-stimulated activity, thus suggesting possible redox regulation of this enzyme complex. Taken together these findings suggest that Lon protease may be particularly vulnerable to inactivation in conditions associated with GSH depletion and elevated oxidative stress.",

author = "Lee Stanyer and Wenche J{\o}rgensen and Osamu Hori and Clark, {John B} and Heales, {Simon J R}",

note = "Keywords: Adenosine Triphosphate; Animals; Biological Assay; Brain; Dose-Response Relationship, Drug; Electron Transport Chain Complex Proteins; Energy Metabolism; Glutathione; Male; Mitochondria; Mitochondrial Diseases; Oxidative Stress; Peroxynitrous Acid; Protease La; Rats; Rats, Wistar; Time Factors",

year = "2008",

doi = "10.1016/j.neuint.2008.06.004",

language = "English",

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pages = "95--101",

journal = "Neurochemistry International",

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TY - JOUR

T1 - Inactivation of brain mitochondrial Lon protease by peroxynitrite precedes electron transport chain dysfunction.

AU - Stanyer, Lee

AU - Jørgensen, Wenche

AU - Hori, Osamu

AU - Clark, John B

AU - Heales, Simon J R

N1 - Keywords: Adenosine Triphosphate; Animals; Biological Assay; Brain; Dose-Response Relationship, Drug; Electron Transport Chain Complex Proteins; Energy Metabolism; Glutathione; Male; Mitochondria; Mitochondrial Diseases; Oxidative Stress; Peroxynitrous Acid; Protease La; Rats; Rats, Wistar; Time Factors

PY - 2008

Y1 - 2008

N2 - The accumulation of oxidatively modified proteins has been shown to be a characteristic feature of many neurodegenerative disorders and its regulation requires efficient proteolytic processing. One component of the mitochondrial proteolytic system is Lon, an ATP-dependent protease that has been shown to degrade oxidatively modified aconitase in vitro and may thus play a role in defending against the accumulation of oxidized matrix proteins in mitochondria. Using an assay system that allowed us to distinguish between basal and ATP-stimulated Lon protease activity, we have shown in isolated non-synaptic rat brain mitochondria that Lon protease is highly susceptible to oxidative inactivation by peroxynitrite (ONOO(-)). This susceptibility was more pronounced with regard to ATP-stimulated activity, which was inhibited by 75% in the presence of a bolus addition of 1mM ONOO(-), whereas basal unstimulated activity was inhibited by 45%. Treatment of mitochondria with a range of peroxynitrite concentrations (10-1000 microM) revealed that a decline in Lon protease activity preceded electron transport chain (ETC) dysfunction (complex I, II-III and IV) and that ATP-stimulated activity was approximately fivefold more sensitive than basal Lon protease activity. Furthermore, supplementation of mitochondrial matrix extracts with reduced glutathione, following ONOO(-) exposure, resulted in partial restoration of basal and ATP-stimulated activity, thus suggesting possible redox regulation of this enzyme complex. Taken together these findings suggest that Lon protease may be particularly vulnerable to inactivation in conditions associated with GSH depletion and elevated oxidative stress.

AB - The accumulation of oxidatively modified proteins has been shown to be a characteristic feature of many neurodegenerative disorders and its regulation requires efficient proteolytic processing. One component of the mitochondrial proteolytic system is Lon, an ATP-dependent protease that has been shown to degrade oxidatively modified aconitase in vitro and may thus play a role in defending against the accumulation of oxidized matrix proteins in mitochondria. Using an assay system that allowed us to distinguish between basal and ATP-stimulated Lon protease activity, we have shown in isolated non-synaptic rat brain mitochondria that Lon protease is highly susceptible to oxidative inactivation by peroxynitrite (ONOO(-)). This susceptibility was more pronounced with regard to ATP-stimulated activity, which was inhibited by 75% in the presence of a bolus addition of 1mM ONOO(-), whereas basal unstimulated activity was inhibited by 45%. Treatment of mitochondria with a range of peroxynitrite concentrations (10-1000 microM) revealed that a decline in Lon protease activity preceded electron transport chain (ETC) dysfunction (complex I, II-III and IV) and that ATP-stimulated activity was approximately fivefold more sensitive than basal Lon protease activity. Furthermore, supplementation of mitochondrial matrix extracts with reduced glutathione, following ONOO(-) exposure, resulted in partial restoration of basal and ATP-stimulated activity, thus suggesting possible redox regulation of this enzyme complex. Taken together these findings suggest that Lon protease may be particularly vulnerable to inactivation in conditions associated with GSH depletion and elevated oxidative stress.

U2 - 10.1016/j.neuint.2008.06.004

DO - 10.1016/j.neuint.2008.06.004

M3 - Journal article

C2 - 18598728

SN - 0197-0186

VL - 53

SP - 95

EP - 101

JO - Neurochemistry International

JF - Neurochemistry International

IS - 3-4

ER -

Inactivation of brain mitochondrial Lon protease by peroxynitrite precedes electron transport chain dysfunction.

Abstract

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