Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease, 2018
Methionine sulfoxide reductase enzymes are a protective system against biological oxidative stres... more Methionine sulfoxide reductase enzymes are a protective system against biological oxidative stress in aerobic organisms. Modifications to this antioxidant system have been shown to impact the lifespan of several model system organisms. In humans, methionine oxidation of critical proteins and deficiencies in the methionine sulfoxide reductase system have been linked to age-related diseases, including cancer and neurodegenerative disease. Substrates for methionine sulfoxide reductases have been reviewed multiple times, and are still an active area of discovery. In contrast, less is known about the genetic regulation of methionine sulfoxide reductases. In this review, we discuss studies on the genetic regulation of the methionine sulfoxide reductase system with relevance to longevity and age-related diseases. A better understanding of genetic regulation for methionine sulfoxide reductases may lead to new therapeutic approaches for age-related diseases in the future.
PILB has been described as being involved in the virulence of bacteria of Neisseria genus. The PI... more PILB has been described as being involved in the virulence of bacteria of Neisseria genus. The PILB protein is composed of three subdomains. In the present study, the central subdomain (PILB-MsrA), the C terminus subdomain (PILB-MsrB), and the fused subdomain (PILB-MsrA/ MsrB) of N. meningitidis were produced as folded entities. The central subdomain shows a methionine sulfoxide reductase A (MsrA) activity, whereas PILB-MsrB displays a methionine sulfoxide reductase B (MsrB) activity. The catalytic mechanism of PILB-MsrB can be divided into two steps: 1) an attack of the Cys-494 on the sulfur atom of the sulfoxide substrate, leading to formation of a sulfenic acid intermediate and release of 1 mol of methionine/mol of enzyme and 2) a regeneration of Cys-494 via formation of an intradisulfide bond with Cys-439 followed by reduction with thioredoxin. The study also shows that 1) MsrA and MsrB display opposite stereoselectivities toward the sulfoxide function; 2) the active sites of both Msrs, particularly MsrB, are rather adapted for binding proteinbound MetSO more efficiently than free MetSO; 3) the carbon C␣ is not a determining factor for efficient binding to both Msrs; and 4) the presence of the sulfoxide function is a prerequisite for binding to Msrs. The fact that the two Msrs exhibit opposite stereoselectivities argues for a structure of the active site of MsrBs different from that of MsrAs. This is further supported by the absence of sequence homology between the two Msrs in particular around the cysteine that is involved in formation of the sulfenic acid derivative. The fact that the catalytic mechanism takes place through formation of a sulfenic acid intermediate for both Msrs supports the idea that sulfenic acid chemistry is a general feature in the reduction of sulfoxides by thiols.
The brain during Alzheimer’s disease (AD) is under severe oxidative attack by reactive oxygen spe... more The brain during Alzheimer’s disease (AD) is under severe oxidative attack by reactive oxygen species that may lead to methionine oxidation. Oxidation of the sole methionine (Met35) of beta-amyloid (Aβ), and possibly methionine residues of other extracellular proteins, may be one of the earliest events contributing to the toxicity of Aβ and other proteins in vivo. In the current study, we immunized transgenic AD (APP/PS1) mice at 4 months of age with a recombinant methionine sulfoxide (MetO)-rich protein from Zea mays (antigen). This treatment induced the production of anti-MetO antibody in blood-plasma that exhibits a significant titer up to at least 10 months of age. Compared to the control mice, the antigen-injected mice exhibited the following significant phenotypes at 10 months of age: better short and long memory capabilities; reduced Aβ levels in both blood-plasma and brain; reduced Aβ burden and MetO accumulations in astrocytes in hippocampal and cortical regions; reduced le...
Previous studies have indicated that human immunodeficiency virus type 1 (HIV-1) protease inhibit... more Previous studies have indicated that human immunodeficiency virus type 1 (HIV-1) protease inhibitors (PIs) are less active at blocking viral replication in HIV-1 infected peripheral blood monocytes/macrophages (M/M) than in HIV-1-infected T cells. We explored the hypothesis that oxidative modification and/or metabolism of the PIs in M/M might account for this reduced potency. We first tested the susceptibility of several PIs (kynostatin-272 [KNI-272], saquinavir, indinavir, ritonavir, or JE-2147) to oxidation after exposure to hydro-gen peroxide (H2O2): only KNI-272 was highly susceptible to oxidation. Treatment of KNI-272 with low millimolar concentrations of H2O2 resulted in mono-oxidation of the sulfur in the S-methyl cysteine (me-thioalanine) moiety, as determined by reversed-phase high-performance liquid chromatography and mass spectrometry (RP-HPLC/MS). Higher concentrations of H2O2 led to an additional oxidation of the sulfur in the thioproline moiety of KNI-272. None of the ...
Methionine sulfoxide reductases (MsrA and MsrB) protect the biological activity of proteins from ... more Methionine sulfoxide reductases (MsrA and MsrB) protect the biological activity of proteins from oxidative modifications to methionine residues and are important for protecting against the pathological effects of neurodegenerative diseases. In the current study, we characterized the auditory phenotype of the MsrA knockout mouse. Young MsrA knockout mice showed small high-frequency threshold elevations for auditory brainstem response and distortion product otoacoustic emission compared to those of wild-type mice, which progressively worsened in older MsrA knockout mice. MsrA knockout mice showed an increased sensitivity to noise at young and older ages, suggesting that MsrA is part of a mechanism that protects the cochlea from acoustic damage. MsrA mRNA in the cochlea was increased following acoustic stimulation. Finally, expression of mRNA MsrB1 was compromised at 6 months old, but not in younger MsrA knockout mice (compared to controls). The identification of MsrA in the cochlea as...
The world journal of biological psychiatry : the official journal of the World Federation of Societies of Biological Psychiatry, Apr 26, 2016
The enzyme catechol-O-methyltransferase (COMT), which catalyses the degradation of dopamine and n... more The enzyme catechol-O-methyltransferase (COMT), which catalyses the degradation of dopamine and norepinephrine, is posited to participate in the pathophysiology of bipolar disorder (BD) and schizophrenia. In support of this notion, rich evidence has documented that the severity of various BD and schizophrenia symptoms is moderated by rs4680, a single nucleotide polymorphism of the COMT gene featuring a valine (Val)-to-methionine (Met) substitution that results in lower catalytic activity. Nevertheless, the specific relevance of COMT enzymatic activity in the pathophysiology of BD and schizophrenia dimensions remains elusive. We measured COMT catalytic activity in post-mortem prefrontal cortices, striata and cerebella of schizophrenia and BD patients, as well as non-affected controls. These values were then correlated with rs4680 genotypes and psychopathology scores in the last week of life. No direct correlation between COMT activity and rs4680 genotypes was found; however, the seve...
Previous studies employing two-dimensional gel electrophoresis and N-terminal protein sequencing ... more Previous studies employing two-dimensional gel electrophoresis and N-terminal protein sequencing have shown elevated synthesis of the enzyme methionine sulfoxide reductase (MsrA) in Staphylococcus aureus in response to cell-wall-active antibiotics. In the present study, the S. aureus msrA gene was cloned, overexpressed, purified as His-tagged MsrA and shown to have methionine sulfoxide reductase activity. The transcription of msrA was studied by assaying β-galactosidase activity in an msrA promoter ::lacZ fusion strain and by Northern blot analysis. Transcription of msrA was increased by oxacillin ; but not by a variety of other stresses including H 2 O 2. Northern blot analysis revealed that the size of the msrA transcript was 23 kb, considerably larger than the 531 nt msrA ORF. The msrA transcription start site was mapped 25 nt upstream of the msrA start codon. Computer analysis from database sequences indicated at least three additional ORFs downstream of msrA. The deduced amino acid sequences of two of these three ORFs showed significant sequence homologies to PilB, and enzyme IIA of the phosphotransferase system, respectively. The third ORF could not be identified by homology searches. Northern blot hybridization with probes specific to the msrA downstream region indicated that the S. aureus msrA was transcribed as part of a polycistronic message. Interestingly, purified S. aureus PilB was shown to possess " " 28-fold higher methionine sulfoxide reductase activity than the MsrA. An insertional knockout mutation in the first gene of this operon resulted in increased susceptibility of the mutant to H 2 O 2 compared to the parent strain, but not to oxacillin.
Proceedings of the National Academy of Sciences of the United States of America, Jan 24, 2003
Mammals contain two methionine sulfoxide (MetO) reductases, MsrA and MsrB, that catalyze the thio... more Mammals contain two methionine sulfoxide (MetO) reductases, MsrA and MsrB, that catalyze the thioredoxin-dependent reduction of the S-MetO and R-MetO derivatives, respectively, to methionine. The major mammalian MsrB is a selenoprotein (except in the heart). Here, we show that there is a loss of MsrB activity in the MsrA-/- mouse that correlates with parallel losses in the levels of MsrB mRNA and MsrB protein, suggesting that MsrA might have a role in MsrB transcription. Moreover, mice that were grown on a selenium-deficient (SD) diet showed a substantial decrease in the levels of MsrB-catalytic activity, MsrB protein, and MsrB mRNA in liver and kidney tissues of both WT and MsrA-/- mouse strains. Whereas no significant protein-MetO could be detected in tissue proteins of young mature mice grown on a selenium-adequate diet, growth on the SD diet led to substantial accumulations of MetO in proteins and also of protein carbonyl derivatives in the liver, kidney, cerebrum, and cerebellu...
On page 4 of this published article an error in Figure 2(a) has occurred. Accordingly, Figure 2(a... more On page 4 of this published article an error in Figure 2(a) has occurred. Accordingly, Figure 2(a) has been replaced with a corrected version of the figure as shown below.
Methionine oxidation by reactive oxygen species and reduction mediated by the methionine sulfoxid... more Methionine oxidation by reactive oxygen species and reduction mediated by the methionine sulfoxide reductase (Msr) system may attenuate protein function in signal transduction pathways. This review will focus on two potential protein targets for methionine oxidation involved in signal transduction of the immune response: Ca 2+ /calmodulin-regulated phosphatase calcineurin (Cn) and inhibitor of kappa B-alpha (IkBα). The major known function of Cn is to regulate nuclear localization of the nuclear factor of activated T cells (NFAT), a family of transcription factors during immune stimulus. Like wise, IκBα inhibits the activity of nuclear factor kappa B (NFkB), which is known to regulate the transcription of various genes participating in immunological and oxidative stress response. Modification of Met 45 in IκBα enhances its resistance to protein-degredation; thereby, preventing NFkB from activating transcription in cells of the immune system. Similarly, the human Cn molecule contains several methionine residues that are either located next to a cysteine residue or a methionine residue. Accordingly, it is suggested that oxidation of a specific Cn-methionine may interfere with the proper NFAT nuclear-localization and transcriptional activation in T-cell. Thus, the roles of oxidized-methionine residues and their reduction, by the Msr system, are discussed as potential regulators of cellular immune response.
Proceedings of the National Academy of Sciences, 2001
Oxidation of proteins by reactive oxygen species is associated with aging, oxidative stress, and ... more Oxidation of proteins by reactive oxygen species is associated with aging, oxidative stress, and many diseases. Although free and protein-bound methionine residues are particularly sensitive to oxidation to methionine sulfoxide derivatives, these oxidations are readily repaired by the action of methionine sulfoxide reductase (MsrA). To gain a better understanding of the biological roles of MsrA in metabolism, we have created a strain of mouse that lacks the MsrA gene. Compared with the wild type, this mutant: ( i ) exhibits enhanced sensitivity to oxidative stress (exposure to 100% oxygen); ( ii ) has a shorter lifespan under both normal and hyperoxic conditions; ( iii ) develops an atypical (tip-toe) walking pattern after 6 months of age; ( iv ) accumulates higher tissue levels of oxidized protein (carbonyl derivatives) under oxidative stress; and ( v ) is less able to up-regulate expression of thioredoxin reductase under oxidative stress. It thus seems that MsrA may play an import...
Staphylococcus aureus contains three genes encoding MsrA-specific methionine sulfoxide reductase ... more Staphylococcus aureus contains three genes encoding MsrA-specific methionine sulfoxide reductase (Msr) activity (msrA1, msrA2 and msrA3) and an additional gene that encodes MsrB-specific Msr activity. Data presented here suggest that MsrA1 is the major contributor of the MsrA activity in S. aureus. In mutational analysis, while the total Msr activity in msrA2 mutant was comparable to that of the parent, Msr activity was significantly up-regulated in the msrA1 or msrA1 msrA2 double mutant. Assessment of substrate specificity together with increased reactivity of the cell-free protein extracts of the msrA1 mutants to anti-MsrB polyclonal antibodies in Western analysis provided evidence that increased Msr activity was due to elevated synthesis of MsrB in the MsrA1 mutants. Previously, it was reported that oxacillin treatment of S. aureus cells led to induced synthesis of MsrA1 and a mutation in msrA1 increased the susceptibility of the organism to H2O2. A mutation in the msrA2 gene, ho...
Previous research suggests that brain oxidative stress and altered rodent locomotor behavior are ... more Previous research suggests that brain oxidative stress and altered rodent locomotor behavior are linked. We observed bio-behavioral changes in methionine sulfoxide reductase A knockout mice associated with abnormal dopamine signaling. Compromised ability of these knockout mice to reduce methionine sulfoxide enhances accumulation of sulfoxides in proteins. We examined the dopamine D 2-receptor function and expression, which has an atypical arrangement and quantity of methionine residues. Indeed, protein expression levels of dopamine D 2-receptor were higher in knockout mice compared with wild-type. However, the binding of dopamine D 2-receptor agonist was compromised in the same fractions of knockout mice. Coupling efficiency of dopamine D 2-receptors to G-proteins was also significantly reduced in knockout mice, supporting the compromised agonist binding. Furthermore, pre-synaptic dopamine release in knockout striatal sections was less responsive than control sections to dopamine D 2-receptor ligands. Behaviorally, the locomotor activity of knockout mice was less responsive to the inhibitory effect of quinpirole than wild-type mice. Involvement of specific methionine residue oxidation in the dopamine D 2-receptor third intracellular loop is suggested by in vitro studies. We conclude that ablation of methionine sulfoxide reductase can affect dopamine signaling through altering dopamine D 2-receptor physiology and may be related to symptoms associated with neurological disorders and diseases.
Back ground: Convergent evidence suggests that oxidative stress plays a central role in the patho... more Back ground: Convergent evidence suggests that oxidative stress plays a central role in the pathology of Alzheimer's disease (AD). We asked if consequently, oxidation of methionine residues to methionine sulfoxide (MetO) was increased in plasma proteins of persons carrying familial AD (FAD) mutations. Methods: Plasma was collected from 31 persons from families harboring PSEN1 or APP mutations. Using Western blot analysis with a novel anti-MetO polyclonal antibody, MetO levels were measured and compared between FAD mutation carriers (MCs) and non-mutation carrying (NCs) kin. Results: A MetO-positive 120-kDa gel band distinguished FAD MCs and NCs (mean 11.4 ± 2.8 vs. 4.0 ± 3.1, p = 0.02). In a subset of subjects for whom both measurements were available, MetO levels correlated well with plasma F2isoprostane (r = 0.81, p < 0.001) and superoxide dismutase 1 (r = 0.52, p = 0.004) levels. Conclusion: Our data provide evidence for elevated MetO levels in persons carrying FAD mutations that correlate with other indices of oxidative stress and suggest that plasma oxidative stress markers may be useful for diagnosis of AD.
Angiogenesis is regulated by hyperglycemic conditions, which can induce cellular stress responses... more Angiogenesis is regulated by hyperglycemic conditions, which can induce cellular stress responses, reactive oxygen species (ROS), and anti-oxidant defenses that modulate intracellular signaling to prevent oxidative damage. The RUNX2 DNA-binding transcription factor is activated by a glucose-mediated intracellular pathway, plays an important role in endothelial cell (EC) function and angiogenesis, and is a target of oxidative stress. RUNX2 DNA-binding and EC differentiation in response to glucose were conserved in ECs from different tissues and inhibited by hyperglycemia, which stimulated ROS production through the aldose reductase glucoseutilization pathway. Furthermore, the redox status of cysteine and methionine residues regulated RUNX2 DNA-binding and reversal of oxidative inhibition was consistent with an endogenous Methionine sulfoxide reductase-A (MsrA) activity. Low molecular weight MsrA substrates and
It is commonly accepted that aging is associated with a decline in the antioxidant defense of the... more It is commonly accepted that aging is associated with a decline in the antioxidant defense of the cell; accordingly, certain redox enzymes are used as markers of biological senescence. To further test and specify this general concept, we studied age-related changes in the enzymes of the methionine-centered redox cycle (MCRC) in four aero-digestive organs of rats. The levels of cytosolic thioredoxin (Trx), thioredoxin reductase (TrxR), and methionine sulfoxide reductase (Msr), all tended to decline with age. The enzymatic activities of MsrA and MsrB were significantly lower in the organs of aged animals. In general, the magnitude of this decline increased in the order: tongue &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; sternohyoid muscle &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; larynx &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; esophagus. The relative stability of MCRC in the old tongues might be part of the well-preserved oxidative metabolism as confirmed by the age-related increase in mitochondrial marker and muscle tissue in these tongues. In total, the results suggest that age-associated oxidative damage is organ-specific and could reflect differences in morphological composition of these tissues, and among them, relative content of striated muscles.
Aims—The enzyme catechol-O-methyl transferase (COMT) plays a primary role in the metabolism of ca... more Aims—The enzyme catechol-O-methyl transferase (COMT) plays a primary role in the metabolism of catecholamine neurotransmitters and is implicated in the modulation of cognitive and emotional responses. The best-characterized single nucleotide polymorphism (SNP) of the COMT gene consists of a valine (Val)-to-methionine (Met) substitution at codon 108/158. The Met-containing variant confers a marked reduction in COMT catalytic activity. We recently showed that the activity of recombinant COMT is positively regulated by the enzyme Met sulfoxide reductase (MSR), which counters the oxidation of Met residues of proteins. The current study was designed to assess whether brain COMT activity may be correlated to MSR in an alleledependent fashion. Methods—COMT and MSR activities were measured from post-mortem samples of prefrontal cortices, striata and cerebella of 32 subjects, by using catechol and dabsyl-Met sulfoxide as substrates, respectively. Allelic discrimination of COMT Val108/185Met ...
Objective: Sporadic Alzheimer's disease (AD) is an oxidative, stress-dependent neurodegenerat... more Objective: Sporadic Alzheimer's disease (AD) is an oxidative, stress-dependent neurodegenerative disease. We investigated whether the levels of protein-methionine sulfoxide (MetO) in plasma could be a possible marker for AD in individuals with mild cognitive impariment (MCI). Design: We evaluated blood samples from patients with AD or MCI, as well as from normal controls, testing their MetO levels and superoxide dismutase (SOD) specific activity. Results: An increase of MetO levels of a particular protein of human plasma and a decrease of SOD activity were observed only in AD plasma. Conclusion: Monitoring the patterns of these plasma markers in patients with MCI could provide a warning sign for disease progression into AD.
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease, 2018
Methionine sulfoxide reductase enzymes are a protective system against biological oxidative stres... more Methionine sulfoxide reductase enzymes are a protective system against biological oxidative stress in aerobic organisms. Modifications to this antioxidant system have been shown to impact the lifespan of several model system organisms. In humans, methionine oxidation of critical proteins and deficiencies in the methionine sulfoxide reductase system have been linked to age-related diseases, including cancer and neurodegenerative disease. Substrates for methionine sulfoxide reductases have been reviewed multiple times, and are still an active area of discovery. In contrast, less is known about the genetic regulation of methionine sulfoxide reductases. In this review, we discuss studies on the genetic regulation of the methionine sulfoxide reductase system with relevance to longevity and age-related diseases. A better understanding of genetic regulation for methionine sulfoxide reductases may lead to new therapeutic approaches for age-related diseases in the future.
PILB has been described as being involved in the virulence of bacteria of Neisseria genus. The PI... more PILB has been described as being involved in the virulence of bacteria of Neisseria genus. The PILB protein is composed of three subdomains. In the present study, the central subdomain (PILB-MsrA), the C terminus subdomain (PILB-MsrB), and the fused subdomain (PILB-MsrA/ MsrB) of N. meningitidis were produced as folded entities. The central subdomain shows a methionine sulfoxide reductase A (MsrA) activity, whereas PILB-MsrB displays a methionine sulfoxide reductase B (MsrB) activity. The catalytic mechanism of PILB-MsrB can be divided into two steps: 1) an attack of the Cys-494 on the sulfur atom of the sulfoxide substrate, leading to formation of a sulfenic acid intermediate and release of 1 mol of methionine/mol of enzyme and 2) a regeneration of Cys-494 via formation of an intradisulfide bond with Cys-439 followed by reduction with thioredoxin. The study also shows that 1) MsrA and MsrB display opposite stereoselectivities toward the sulfoxide function; 2) the active sites of both Msrs, particularly MsrB, are rather adapted for binding proteinbound MetSO more efficiently than free MetSO; 3) the carbon C␣ is not a determining factor for efficient binding to both Msrs; and 4) the presence of the sulfoxide function is a prerequisite for binding to Msrs. The fact that the two Msrs exhibit opposite stereoselectivities argues for a structure of the active site of MsrBs different from that of MsrAs. This is further supported by the absence of sequence homology between the two Msrs in particular around the cysteine that is involved in formation of the sulfenic acid derivative. The fact that the catalytic mechanism takes place through formation of a sulfenic acid intermediate for both Msrs supports the idea that sulfenic acid chemistry is a general feature in the reduction of sulfoxides by thiols.
The brain during Alzheimer’s disease (AD) is under severe oxidative attack by reactive oxygen spe... more The brain during Alzheimer’s disease (AD) is under severe oxidative attack by reactive oxygen species that may lead to methionine oxidation. Oxidation of the sole methionine (Met35) of beta-amyloid (Aβ), and possibly methionine residues of other extracellular proteins, may be one of the earliest events contributing to the toxicity of Aβ and other proteins in vivo. In the current study, we immunized transgenic AD (APP/PS1) mice at 4 months of age with a recombinant methionine sulfoxide (MetO)-rich protein from Zea mays (antigen). This treatment induced the production of anti-MetO antibody in blood-plasma that exhibits a significant titer up to at least 10 months of age. Compared to the control mice, the antigen-injected mice exhibited the following significant phenotypes at 10 months of age: better short and long memory capabilities; reduced Aβ levels in both blood-plasma and brain; reduced Aβ burden and MetO accumulations in astrocytes in hippocampal and cortical regions; reduced le...
Previous studies have indicated that human immunodeficiency virus type 1 (HIV-1) protease inhibit... more Previous studies have indicated that human immunodeficiency virus type 1 (HIV-1) protease inhibitors (PIs) are less active at blocking viral replication in HIV-1 infected peripheral blood monocytes/macrophages (M/M) than in HIV-1-infected T cells. We explored the hypothesis that oxidative modification and/or metabolism of the PIs in M/M might account for this reduced potency. We first tested the susceptibility of several PIs (kynostatin-272 [KNI-272], saquinavir, indinavir, ritonavir, or JE-2147) to oxidation after exposure to hydro-gen peroxide (H2O2): only KNI-272 was highly susceptible to oxidation. Treatment of KNI-272 with low millimolar concentrations of H2O2 resulted in mono-oxidation of the sulfur in the S-methyl cysteine (me-thioalanine) moiety, as determined by reversed-phase high-performance liquid chromatography and mass spectrometry (RP-HPLC/MS). Higher concentrations of H2O2 led to an additional oxidation of the sulfur in the thioproline moiety of KNI-272. None of the ...
Methionine sulfoxide reductases (MsrA and MsrB) protect the biological activity of proteins from ... more Methionine sulfoxide reductases (MsrA and MsrB) protect the biological activity of proteins from oxidative modifications to methionine residues and are important for protecting against the pathological effects of neurodegenerative diseases. In the current study, we characterized the auditory phenotype of the MsrA knockout mouse. Young MsrA knockout mice showed small high-frequency threshold elevations for auditory brainstem response and distortion product otoacoustic emission compared to those of wild-type mice, which progressively worsened in older MsrA knockout mice. MsrA knockout mice showed an increased sensitivity to noise at young and older ages, suggesting that MsrA is part of a mechanism that protects the cochlea from acoustic damage. MsrA mRNA in the cochlea was increased following acoustic stimulation. Finally, expression of mRNA MsrB1 was compromised at 6 months old, but not in younger MsrA knockout mice (compared to controls). The identification of MsrA in the cochlea as...
The world journal of biological psychiatry : the official journal of the World Federation of Societies of Biological Psychiatry, Apr 26, 2016
The enzyme catechol-O-methyltransferase (COMT), which catalyses the degradation of dopamine and n... more The enzyme catechol-O-methyltransferase (COMT), which catalyses the degradation of dopamine and norepinephrine, is posited to participate in the pathophysiology of bipolar disorder (BD) and schizophrenia. In support of this notion, rich evidence has documented that the severity of various BD and schizophrenia symptoms is moderated by rs4680, a single nucleotide polymorphism of the COMT gene featuring a valine (Val)-to-methionine (Met) substitution that results in lower catalytic activity. Nevertheless, the specific relevance of COMT enzymatic activity in the pathophysiology of BD and schizophrenia dimensions remains elusive. We measured COMT catalytic activity in post-mortem prefrontal cortices, striata and cerebella of schizophrenia and BD patients, as well as non-affected controls. These values were then correlated with rs4680 genotypes and psychopathology scores in the last week of life. No direct correlation between COMT activity and rs4680 genotypes was found; however, the seve...
Previous studies employing two-dimensional gel electrophoresis and N-terminal protein sequencing ... more Previous studies employing two-dimensional gel electrophoresis and N-terminal protein sequencing have shown elevated synthesis of the enzyme methionine sulfoxide reductase (MsrA) in Staphylococcus aureus in response to cell-wall-active antibiotics. In the present study, the S. aureus msrA gene was cloned, overexpressed, purified as His-tagged MsrA and shown to have methionine sulfoxide reductase activity. The transcription of msrA was studied by assaying β-galactosidase activity in an msrA promoter ::lacZ fusion strain and by Northern blot analysis. Transcription of msrA was increased by oxacillin ; but not by a variety of other stresses including H 2 O 2. Northern blot analysis revealed that the size of the msrA transcript was 23 kb, considerably larger than the 531 nt msrA ORF. The msrA transcription start site was mapped 25 nt upstream of the msrA start codon. Computer analysis from database sequences indicated at least three additional ORFs downstream of msrA. The deduced amino acid sequences of two of these three ORFs showed significant sequence homologies to PilB, and enzyme IIA of the phosphotransferase system, respectively. The third ORF could not be identified by homology searches. Northern blot hybridization with probes specific to the msrA downstream region indicated that the S. aureus msrA was transcribed as part of a polycistronic message. Interestingly, purified S. aureus PilB was shown to possess " " 28-fold higher methionine sulfoxide reductase activity than the MsrA. An insertional knockout mutation in the first gene of this operon resulted in increased susceptibility of the mutant to H 2 O 2 compared to the parent strain, but not to oxacillin.
Proceedings of the National Academy of Sciences of the United States of America, Jan 24, 2003
Mammals contain two methionine sulfoxide (MetO) reductases, MsrA and MsrB, that catalyze the thio... more Mammals contain two methionine sulfoxide (MetO) reductases, MsrA and MsrB, that catalyze the thioredoxin-dependent reduction of the S-MetO and R-MetO derivatives, respectively, to methionine. The major mammalian MsrB is a selenoprotein (except in the heart). Here, we show that there is a loss of MsrB activity in the MsrA-/- mouse that correlates with parallel losses in the levels of MsrB mRNA and MsrB protein, suggesting that MsrA might have a role in MsrB transcription. Moreover, mice that were grown on a selenium-deficient (SD) diet showed a substantial decrease in the levels of MsrB-catalytic activity, MsrB protein, and MsrB mRNA in liver and kidney tissues of both WT and MsrA-/- mouse strains. Whereas no significant protein-MetO could be detected in tissue proteins of young mature mice grown on a selenium-adequate diet, growth on the SD diet led to substantial accumulations of MetO in proteins and also of protein carbonyl derivatives in the liver, kidney, cerebrum, and cerebellu...
On page 4 of this published article an error in Figure 2(a) has occurred. Accordingly, Figure 2(a... more On page 4 of this published article an error in Figure 2(a) has occurred. Accordingly, Figure 2(a) has been replaced with a corrected version of the figure as shown below.
Methionine oxidation by reactive oxygen species and reduction mediated by the methionine sulfoxid... more Methionine oxidation by reactive oxygen species and reduction mediated by the methionine sulfoxide reductase (Msr) system may attenuate protein function in signal transduction pathways. This review will focus on two potential protein targets for methionine oxidation involved in signal transduction of the immune response: Ca 2+ /calmodulin-regulated phosphatase calcineurin (Cn) and inhibitor of kappa B-alpha (IkBα). The major known function of Cn is to regulate nuclear localization of the nuclear factor of activated T cells (NFAT), a family of transcription factors during immune stimulus. Like wise, IκBα inhibits the activity of nuclear factor kappa B (NFkB), which is known to regulate the transcription of various genes participating in immunological and oxidative stress response. Modification of Met 45 in IκBα enhances its resistance to protein-degredation; thereby, preventing NFkB from activating transcription in cells of the immune system. Similarly, the human Cn molecule contains several methionine residues that are either located next to a cysteine residue or a methionine residue. Accordingly, it is suggested that oxidation of a specific Cn-methionine may interfere with the proper NFAT nuclear-localization and transcriptional activation in T-cell. Thus, the roles of oxidized-methionine residues and their reduction, by the Msr system, are discussed as potential regulators of cellular immune response.
Proceedings of the National Academy of Sciences, 2001
Oxidation of proteins by reactive oxygen species is associated with aging, oxidative stress, and ... more Oxidation of proteins by reactive oxygen species is associated with aging, oxidative stress, and many diseases. Although free and protein-bound methionine residues are particularly sensitive to oxidation to methionine sulfoxide derivatives, these oxidations are readily repaired by the action of methionine sulfoxide reductase (MsrA). To gain a better understanding of the biological roles of MsrA in metabolism, we have created a strain of mouse that lacks the MsrA gene. Compared with the wild type, this mutant: ( i ) exhibits enhanced sensitivity to oxidative stress (exposure to 100% oxygen); ( ii ) has a shorter lifespan under both normal and hyperoxic conditions; ( iii ) develops an atypical (tip-toe) walking pattern after 6 months of age; ( iv ) accumulates higher tissue levels of oxidized protein (carbonyl derivatives) under oxidative stress; and ( v ) is less able to up-regulate expression of thioredoxin reductase under oxidative stress. It thus seems that MsrA may play an import...
Staphylococcus aureus contains three genes encoding MsrA-specific methionine sulfoxide reductase ... more Staphylococcus aureus contains three genes encoding MsrA-specific methionine sulfoxide reductase (Msr) activity (msrA1, msrA2 and msrA3) and an additional gene that encodes MsrB-specific Msr activity. Data presented here suggest that MsrA1 is the major contributor of the MsrA activity in S. aureus. In mutational analysis, while the total Msr activity in msrA2 mutant was comparable to that of the parent, Msr activity was significantly up-regulated in the msrA1 or msrA1 msrA2 double mutant. Assessment of substrate specificity together with increased reactivity of the cell-free protein extracts of the msrA1 mutants to anti-MsrB polyclonal antibodies in Western analysis provided evidence that increased Msr activity was due to elevated synthesis of MsrB in the MsrA1 mutants. Previously, it was reported that oxacillin treatment of S. aureus cells led to induced synthesis of MsrA1 and a mutation in msrA1 increased the susceptibility of the organism to H2O2. A mutation in the msrA2 gene, ho...
Previous research suggests that brain oxidative stress and altered rodent locomotor behavior are ... more Previous research suggests that brain oxidative stress and altered rodent locomotor behavior are linked. We observed bio-behavioral changes in methionine sulfoxide reductase A knockout mice associated with abnormal dopamine signaling. Compromised ability of these knockout mice to reduce methionine sulfoxide enhances accumulation of sulfoxides in proteins. We examined the dopamine D 2-receptor function and expression, which has an atypical arrangement and quantity of methionine residues. Indeed, protein expression levels of dopamine D 2-receptor were higher in knockout mice compared with wild-type. However, the binding of dopamine D 2-receptor agonist was compromised in the same fractions of knockout mice. Coupling efficiency of dopamine D 2-receptors to G-proteins was also significantly reduced in knockout mice, supporting the compromised agonist binding. Furthermore, pre-synaptic dopamine release in knockout striatal sections was less responsive than control sections to dopamine D 2-receptor ligands. Behaviorally, the locomotor activity of knockout mice was less responsive to the inhibitory effect of quinpirole than wild-type mice. Involvement of specific methionine residue oxidation in the dopamine D 2-receptor third intracellular loop is suggested by in vitro studies. We conclude that ablation of methionine sulfoxide reductase can affect dopamine signaling through altering dopamine D 2-receptor physiology and may be related to symptoms associated with neurological disorders and diseases.
Back ground: Convergent evidence suggests that oxidative stress plays a central role in the patho... more Back ground: Convergent evidence suggests that oxidative stress plays a central role in the pathology of Alzheimer's disease (AD). We asked if consequently, oxidation of methionine residues to methionine sulfoxide (MetO) was increased in plasma proteins of persons carrying familial AD (FAD) mutations. Methods: Plasma was collected from 31 persons from families harboring PSEN1 or APP mutations. Using Western blot analysis with a novel anti-MetO polyclonal antibody, MetO levels were measured and compared between FAD mutation carriers (MCs) and non-mutation carrying (NCs) kin. Results: A MetO-positive 120-kDa gel band distinguished FAD MCs and NCs (mean 11.4 ± 2.8 vs. 4.0 ± 3.1, p = 0.02). In a subset of subjects for whom both measurements were available, MetO levels correlated well with plasma F2isoprostane (r = 0.81, p < 0.001) and superoxide dismutase 1 (r = 0.52, p = 0.004) levels. Conclusion: Our data provide evidence for elevated MetO levels in persons carrying FAD mutations that correlate with other indices of oxidative stress and suggest that plasma oxidative stress markers may be useful for diagnosis of AD.
Angiogenesis is regulated by hyperglycemic conditions, which can induce cellular stress responses... more Angiogenesis is regulated by hyperglycemic conditions, which can induce cellular stress responses, reactive oxygen species (ROS), and anti-oxidant defenses that modulate intracellular signaling to prevent oxidative damage. The RUNX2 DNA-binding transcription factor is activated by a glucose-mediated intracellular pathway, plays an important role in endothelial cell (EC) function and angiogenesis, and is a target of oxidative stress. RUNX2 DNA-binding and EC differentiation in response to glucose were conserved in ECs from different tissues and inhibited by hyperglycemia, which stimulated ROS production through the aldose reductase glucoseutilization pathway. Furthermore, the redox status of cysteine and methionine residues regulated RUNX2 DNA-binding and reversal of oxidative inhibition was consistent with an endogenous Methionine sulfoxide reductase-A (MsrA) activity. Low molecular weight MsrA substrates and
It is commonly accepted that aging is associated with a decline in the antioxidant defense of the... more It is commonly accepted that aging is associated with a decline in the antioxidant defense of the cell; accordingly, certain redox enzymes are used as markers of biological senescence. To further test and specify this general concept, we studied age-related changes in the enzymes of the methionine-centered redox cycle (MCRC) in four aero-digestive organs of rats. The levels of cytosolic thioredoxin (Trx), thioredoxin reductase (TrxR), and methionine sulfoxide reductase (Msr), all tended to decline with age. The enzymatic activities of MsrA and MsrB were significantly lower in the organs of aged animals. In general, the magnitude of this decline increased in the order: tongue &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; sternohyoid muscle &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; larynx &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; esophagus. The relative stability of MCRC in the old tongues might be part of the well-preserved oxidative metabolism as confirmed by the age-related increase in mitochondrial marker and muscle tissue in these tongues. In total, the results suggest that age-associated oxidative damage is organ-specific and could reflect differences in morphological composition of these tissues, and among them, relative content of striated muscles.
Aims—The enzyme catechol-O-methyl transferase (COMT) plays a primary role in the metabolism of ca... more Aims—The enzyme catechol-O-methyl transferase (COMT) plays a primary role in the metabolism of catecholamine neurotransmitters and is implicated in the modulation of cognitive and emotional responses. The best-characterized single nucleotide polymorphism (SNP) of the COMT gene consists of a valine (Val)-to-methionine (Met) substitution at codon 108/158. The Met-containing variant confers a marked reduction in COMT catalytic activity. We recently showed that the activity of recombinant COMT is positively regulated by the enzyme Met sulfoxide reductase (MSR), which counters the oxidation of Met residues of proteins. The current study was designed to assess whether brain COMT activity may be correlated to MSR in an alleledependent fashion. Methods—COMT and MSR activities were measured from post-mortem samples of prefrontal cortices, striata and cerebella of 32 subjects, by using catechol and dabsyl-Met sulfoxide as substrates, respectively. Allelic discrimination of COMT Val108/185Met ...
Objective: Sporadic Alzheimer's disease (AD) is an oxidative, stress-dependent neurodegenerat... more Objective: Sporadic Alzheimer's disease (AD) is an oxidative, stress-dependent neurodegenerative disease. We investigated whether the levels of protein-methionine sulfoxide (MetO) in plasma could be a possible marker for AD in individuals with mild cognitive impariment (MCI). Design: We evaluated blood samples from patients with AD or MCI, as well as from normal controls, testing their MetO levels and superoxide dismutase (SOD) specific activity. Results: An increase of MetO levels of a particular protein of human plasma and a decrease of SOD activity were observed only in AD plasma. Conclusion: Monitoring the patterns of these plasma markers in patients with MCI could provide a warning sign for disease progression into AD.
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