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Nyarko JNK, Heistad RM, Pennington PR, Mousseau DD. Detecting Monoamine Oxidase A and B Proteins: A Western Blotting Protocol and Some Practical Considerations. Methods Mol Biol 2023; 2558:123-141. [PMID: 36169860 DOI: 10.1007/978-1-0716-2643-6_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The expression of the two isoforms of monoamine oxidase (MAO A and MAO B) is often inferred from proxy measures such as mRNA transcript levels or catalytic activity. Yet the literature is clear that the proportionality of protein, mRNA, and activity does not guarantee that any of these measures can be used as a proxy for any of the others. Here we provide a protocol for the detection of MAO proteins in cell lysates that can be adapted readily to tissue preparations. Given that MAOs influence many physiological and pathological processes, we feel it is essential to include measures of protein expression when exploring genetic regulation or catalytic properties of these important enzymes.
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Affiliation(s)
| | - Ryan M Heistad
- Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Paul R Pennington
- Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Darrell D Mousseau
- Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada.
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2
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Wenzel TJ, Nyarko JNK, Heistad RM, Pennington PR, Phenix CP, Mousseau DD. An (Immuno) Fluorescence Protocol for Monitoring Monoamine Oxidase A/B Protein Distribution Within the Cell. Methods Mol Biol 2023; 2558:143-161. [PMID: 36169861 DOI: 10.1007/978-1-0716-2643-6_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The influence of a protein is not determined exclusively by its level of expression, but also by its localization within the cell. The literature often refers to the enzyme monoamine oxidase (MAO) as a mitochondrial enzyme, yet there is evidence that mitochondria-independent pools of MAO exist. These pools of MAO could exert distinct influences across physiological as well as pathological phenotypes. Fluorescence microscopy is a powerful tool for spatially resolving target proteins in cell and tissue preparations. This can rely on an antibody-based probe that targets the endogenous protein, e.g., immunofluorescence. In the event that antibodies might not be readily available or if one is interested in characterizing a variant of the wild-type protein, then a recombinant protein with a fluorescent fusion "tag" is preferred. We now describe a protocol for the detection of endogenous MAO using indirect immunofluorescence and a version of the protocol with minor modification for detecting (green) fluorescent protein-tagged MAOs. One observation we can highlight using these easily adaptable approaches is that MAO A and MAO B do not follow similar patterns of distribution throughout the cell, suggesting potential expression of MAO A and MAO B on distinct pools of mitochondria. Furthermore, distinct subcellular compartmentalization is suggested by the fact that a pool of MAO A, but not MAO B, is associated with certain lysosomal compartments. However, directed and quantitative studies will be required before any definitive statement can be made on these intriguing possibilities.
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Affiliation(s)
- Tyler J Wenzel
- Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | | | - Ryan M Heistad
- Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Paul R Pennington
- Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Chris P Phenix
- Department of Chemistry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Darrell D Mousseau
- Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada.
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3
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Quartey MO, Nyarko JNK, Maley JM, Barnes JR, Bolanos MAC, Heistad RM, Knudsen KJ, Pennington PR, Buttigieg J, De Carvalho CE, Leary SC, Parsons MP, Mousseau DD. The Aβ(1-38) peptide is a negative regulator of the Aβ(1-42) peptide implicated in Alzheimer disease progression. Sci Rep 2021; 11:431. [PMID: 33432101 PMCID: PMC7801637 DOI: 10.1038/s41598-020-80164-w] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 12/17/2020] [Indexed: 12/14/2022] Open
Abstract
The pool of β-Amyloid (Aβ) length variants detected in preclinical and clinical Alzheimer disease (AD) samples suggests a diversity of roles for Aβ peptides. We examined how a naturally occurring variant, e.g. Aβ(1-38), interacts with the AD-related variant, Aβ(1-42), and the predominant physiological variant, Aβ(1-40). Atomic force microscopy, Thioflavin T fluorescence, circular dichroism, dynamic light scattering, and surface plasmon resonance reveal that Aβ(1-38) interacts differently with Aβ(1-40) and Aβ(1-42) and, in general, Aβ(1-38) interferes with the conversion of Aβ(1-42) to a β-sheet-rich aggregate. Functionally, Aβ(1-38) reverses the negative impact of Aβ(1-42) on long-term potentiation in acute hippocampal slices and on membrane conductance in primary neurons, and mitigates an Aβ(1-42) phenotype in Caenorhabditis elegans. Aβ(1-38) also reverses any loss of MTT conversion induced by Aβ(1-40) and Aβ(1-42) in HT-22 hippocampal neurons and APOE ε4-positive human fibroblasts, although the combination of Aβ(1-38) and Aβ(1-42) inhibits MTT conversion in APOE ε4-negative fibroblasts. A greater ratio of soluble Aβ(1-42)/Aβ(1-38) [and Aβ(1-42)/Aβ(1-40)] in autopsied brain extracts correlates with an earlier age-at-death in males (but not females) with a diagnosis of AD. These results suggest that Aβ(1-38) is capable of physically counteracting, potentially in a sex-dependent manner, the neuropathological effects of the AD-relevant Aβ(1-42).
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Affiliation(s)
- Maa O Quartey
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, GB41 HSB, 107 Wiggins Rd., Saskatoon, SK, S7N 5E5, Canada
| | - Jennifer N K Nyarko
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, GB41 HSB, 107 Wiggins Rd., Saskatoon, SK, S7N 5E5, Canada
| | - Jason M Maley
- Saskatchewan Structural Sciences Centre, University of Saskatchewan, Saskatoon, SK, Canada
| | - Jocelyn R Barnes
- Division of BioMedical Sciences (Neurosciences), Memorial University of Newfoundland, St. John's, NL, Canada
| | | | - Ryan M Heistad
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, GB41 HSB, 107 Wiggins Rd., Saskatoon, SK, S7N 5E5, Canada
| | - Kaeli J Knudsen
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, GB41 HSB, 107 Wiggins Rd., Saskatoon, SK, S7N 5E5, Canada
| | - Paul R Pennington
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, GB41 HSB, 107 Wiggins Rd., Saskatoon, SK, S7N 5E5, Canada
| | - Josef Buttigieg
- Department of Biology, University of Regina, Regina, SK, Canada
| | | | - Scot C Leary
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Matthew P Parsons
- Division of BioMedical Sciences (Neurosciences), Memorial University of Newfoundland, St. John's, NL, Canada
| | - Darrell D Mousseau
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, GB41 HSB, 107 Wiggins Rd., Saskatoon, SK, S7N 5E5, Canada.
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Hayward GC, LeBlanc PJ, Emter CA, Nyarko JNK, Mousseau DD, MacPherson REK, Olver TD. Female Sex Hormones and Cardiac Pressure Overload Independently Contribute to the Cardiogenic Dementia Profile in Yucatan Miniature Swine. Front Cardiovasc Med 2019; 6:129. [PMID: 31552273 PMCID: PMC6746895 DOI: 10.3389/fcvm.2019.00129] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 08/19/2019] [Indexed: 01/29/2023] Open
Abstract
Post-menopausal women with heart failure (HF) frequently exhibit cardiogenic dementia. Using a pre-clinical swine model of post-menopausal HF, we recently demonstrated that experimental menopause (ovariectomy; OVX) and HF (6-month cardiac pressure overload/aortic banding; AB) independently altered cerebral vasomotor control and together impaired cognitive function. The purpose of this study was to examine the prefrontal cortex and hippocampus tissues from these animals to assess whether OVX and HF are associated with neurologic alterations that may contribute to cardiogenic dementia. We hypothesized that OVX and HF would independently alter neuronal cell signaling in swine with post-menopausal cardiogenic dementia. Immunoblot analyses revealed OVX was associated with reduced estrogen receptor-α in both brain regions and HF tended to exacerbate OVX-induced deficits in the hippocampus. Further, OVX was associated with a reduction in the ratio of phosphorylated:total Akt and ERK in the hippocampus as well as decreased total Akt and synaptophysin in the prefrontal cortex. In contrast, HF was associated with a trend toward reduced phosphorylated:total ERK in the prefrontal cortex. In addition, HF was associated with decreased β-amyloid (1-38) in the prefrontal cortex and increased β-amyloid (1-38) in the hippocampus. Regional brain lipid analysis revealed OVX tended to increase total, saturated, and monounsaturated fatty acid content in the prefrontal cortex, with the greatest magnitude of change occurring in the AB-OVX group. The data from this study suggest that OVX and HF are independently associated with regional-specific neurologic changes in the brain that contribute to the cardiogenic dementia profile in this model. This pre-clinical swine model may be a useful tool for better understanding post-menopausal cardiogenic dementia pathology and developing novel therapies.
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Affiliation(s)
- Grant C. Hayward
- Department of Health Sciences, Brock University, St. Catharines, ON, Canada
- Centre for Neuroscience, Brock University, St. Catharines, ON, Canada
| | - Paul J. LeBlanc
- Department of Health Sciences, Brock University, St. Catharines, ON, Canada
- Centre for Bone and Muscle Health, Brock University, St. Catharines, ON, Canada
| | - Craig A. Emter
- Department of Biomedical Sciences, University of Missouri, Columbia, MO, United States
| | - Jennifer N. K. Nyarko
- Department of Psychiatry, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Darrell D. Mousseau
- Department of Psychiatry, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Rebecca E. K. MacPherson
- Department of Health Sciences, Brock University, St. Catharines, ON, Canada
- Centre for Neuroscience, Brock University, St. Catharines, ON, Canada
| | - T. Dylan Olver
- Department of Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada
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Wang S, Vigliarolo BG, Chowdhury MA, Nyarko JNK, Mousseau DD, Phenix CP. Design and synthesis of fluorogenic substrate-based probes for detecting Cathepsin B activity. Bioorg Chem 2019; 92:103194. [PMID: 31493706 DOI: 10.1016/j.bioorg.2019.103194] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/27/2019] [Accepted: 08/11/2019] [Indexed: 11/18/2022]
Abstract
Cathepsin B plays key roles in tumor progression with its overexpression being associated with invasive and metastatic phenotypes and is a primary target of protease activated antibody-directed prodrug therapy. It therefore represents a potential therapeutic and diagnostic target and effort has been made to develop fluorescent probes to report on Cathepsin B activity in cells and animal models of cancer. We have designed, synthesized, and thoroughly evaluated four novel "turn on" probes that employ a lysosomotropic dansylcadaverine dye to report on Cathepsin B activity. Enzyme activity assays using a recombinant human enzyme and cancer cell lysates coupled with confocal microscopy experiments demonstrated that one of the probes, derivatized with the self-immolative prodrug linker p-aminobenzyl alcohol, can selectively report on Cathepsin B in biological samples including live cells.
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Affiliation(s)
- Shusheng Wang
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
| | - Brady G Vigliarolo
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
| | - Morshed A Chowdhury
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
| | - Jennifer N K Nyarko
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK S7N 5E5, Canada
| | - Darrell D Mousseau
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK S7N 5E5, Canada
| | - Christopher P Phenix
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada.
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Quartey MO, Nyarko JNK, Pennington PR, Heistad RM, Chaharyn BM, Wei Z, Bainbridge D, Baker GB, Mousseau DD. Age- and sex-dependent profiles of APP fragments and key secretases align with changes in despair-like behavior and cognition in young APPSwe/Ind mice. Biochem Biophys Res Commun 2019; 511:454-459. [PMID: 30803762 DOI: 10.1016/j.bbrc.2019.02.083] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 02/15/2019] [Indexed: 12/11/2022]
Abstract
Biological sex exerts distinct influences on brain levels of the β-amyloid (Aβ) peptide in both clinical depression and Alzheimer disease (AD), yet studies in animal models focus primarily on males. We examined behavioral 'despair'/depression (using the tail-suspension test) and memory (using the novel object recognition task) in J20 (hAPPSwe/Ind) mice. Three month-old male (but not female) J20 mice exhibited less despair-like behavior, but more evidence of cognitive deficits. In young J20 mice, only soluble Aβ peptides -primarily Aβ(1-40)- were detected. There was no evidence of an effect on despair-like behavior in the six month-old J20 mice, although cognitive deficits were now evident in both sexes, and coincided with a greater proportion of the neurotoxic Aβ(1-42) species (in soluble as well as insoluble fractions). This age-dependent shift in Aβ peptide profile coincided with reduced expression of glycosylated species of ADAM-10 (α-secretase) and BACE1 (β-secretase), and an increased co-immunoprecipitation of presenilin-1 with nicastrin (components of the γ-secretase complex). Sex-dependent changes in depression-related monoaminergic, e.g. serotonin and dopamine (but not noradrenaline), systems were evident already in young J20 mice. It is critical to acknowledge that sex-dependent APP-related phenotypes might differentially influence modifiable depression-related monoaminergic signalling at some of the earliest pathological stages of clinical AD.
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Affiliation(s)
- Maa O Quartey
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, Canada
| | - Jennifer N K Nyarko
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, Canada
| | - Paul R Pennington
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, Canada
| | - Ryan M Heistad
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, Canada
| | - Bradley M Chaharyn
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, Canada
| | - Zelan Wei
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, Canada
| | - Dennis Bainbridge
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, Canada
| | - Glen B Baker
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, Canada
| | - Darrell D Mousseau
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, Canada.
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Nyarko JNK, Quartey MO, Baker GB, Mousseau DD. Can Animal Models Inform on the Relationship between Depression and Alzheimer Disease? Can J Psychiatry 2019; 64:18-29. [PMID: 29685068 PMCID: PMC6364140 DOI: 10.1177/0706743718772514] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The focus on the β-amyloid (Aβ) peptide in clinical Alzheimer disease (AD) as well as in animal models of AD has perhaps biased our understanding of what contributes to the heterogeneity in disease onset and progression. Part of this heterogeneity could reflect the various neuropsychiatric risk factors that present with common symptomatology and can predispose the brain to AD-like changes. One such risk factor is depression. Animal models, particularly mouse models carrying variants of AD-related gene(s), many of which lead to an accumulation of Aβ, suggest that a fundamental shift in depression-related monoaminergic systems (including serotonin and noradrenaline) is a strong indicator of the altered cellular function associated with the earlier(est) stages of AD-related pathology. These changes in monoaminergic neurochemistry could provide for relevant targets for intervention in clinical AD and/or could support a polypharmacy strategy, which might include the targeting of Aβ, in vulnerable populations. Future studies must also include female mice as well as male mice in animal model studies on the relationship between depression and AD.
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Affiliation(s)
- Jennifer N K Nyarko
- 1 Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Maa O Quartey
- 1 Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Glen B Baker
- 2 Department of Psychiatry, Neuroscience and Mental Health Institute, Neurochemical Research Unit, University of Alberta, Edmonton, Alberta, Canada
| | - Darrell D Mousseau
- 1 Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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Nyarko JNK, Quartey MO, Heistad RM, Pennington PR, Poon LJ, Knudsen KJ, Allonby O, El Zawily AM, Freywald A, Rauw G, Baker GB, Mousseau DD. Glycosylation States of Pre- and Post-synaptic Markers of 5-HT Neurons Differ With Sex and 5-HTTLPR Genotype in Cortical Autopsy Samples. Front Neurosci 2018; 12:545. [PMID: 30147642 PMCID: PMC6096231 DOI: 10.3389/fnins.2018.00545] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 07/19/2018] [Indexed: 11/13/2022] Open
Abstract
The serotonin (5-hydroxytryptamine, 5-HT) transporter (5-HTT) gene-linked polymorphic region (5-HTTLPR) is thought to alter 5-HT signaling and contribute to behavioral and cognitive phenotypes in depression as well as Alzheimer disease (AD). We explored how well the short (S) and long (L) alleles of the 5-HTTLPR align with serotoninergic indices in 60 autopsied cortical samples from early-onset AD/EOAD and late-onset AD/LOAD donors, and age- and sex-matched controls. Stratifying data by either diagnosis-by-genotype or by sex-by-genotype revealed that the donor's 5-HTTLPR genotype, i.e., L/L, S/L, or S/S, did not affect 5-HTT mRNA or protein expression. However, the glycosylation of 5-HTT was significantly higher in control female (vs. male) samples and tended to decrease in female EOAD/LOAD samples, but remained unaltered in male LOAD samples. Glycosylated forms of the vesicular monoamine transporter (VMAT2) were lower in both male and female AD samples, while a sex-by-genotype stratification revealed a loss of VMAT2 glycosylation specifically in females with an L/L genotype. VMAT2 and 5-HTT glycosylation were correlated in male samples and inversely correlated in female samples in both stratification models. The S/S genotype aligned with lower levels of 5-HT turnover in females (but not males) and with an increased glycosylation of the post-synaptic 5-HT2C receptor. Interestingly, the changes in presynaptic glycosylation were evident primarily in female carriers of the APOE ε4 risk factor for AD. Our data do not support an association between 5-HTTLPR genotype and 5-HTT expression, but they do reveal a non-canonical association of 5-HTTLPR genotype with sex-dependent glycosylation changes in pre- and post-synaptic markers of serotoninergic neurons. These patterns of change suggest adaptive responses in 5-HT signaling and could certainly be contributing to the female prevalence in risk for either depression or AD.
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Affiliation(s)
- Jennifer N K Nyarko
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Maa O Quartey
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Ryan M Heistad
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Paul R Pennington
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Lisa J Poon
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Kaeli J Knudsen
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Odette Allonby
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Amr M El Zawily
- Department of Pathology and Laboratory Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Andrew Freywald
- Department of Pathology and Laboratory Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Gail Rauw
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Glen B Baker
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Darrell D Mousseau
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
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Quartey MO, Nyarko JNK, Pennington PR, Heistad RM, Klassen PC, Baker GB, Mousseau DD. Alzheimer Disease and Selected Risk Factors Disrupt a Co-regulation of Monoamine Oxidase-A/B in the Hippocampus, but Not in the Cortex. Front Neurosci 2018; 12:419. [PMID: 29997470 PMCID: PMC6029266 DOI: 10.3389/fnins.2018.00419] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 06/01/2018] [Indexed: 01/09/2023] Open
Abstract
Monoamine oxidase-A (MAO-A) and MAO-B have both been implicated in the pathology of Alzheimer disease (AD). We examined 60 autopsied control and AD donor brain samples to determine how well MAO function aligned with two major risk factors for AD, namely sex and APOE ε4 status. MAO-A activity was increased in AD cortical, but not hippocampal, samples. In contrast, MAO-B activity was increased in both regions (with a strong input from female donors) whether sample means were compared based on: (a) diagnosis alone; (b) diagnosis-by-APOE ε4 status (i.e., carriers vs. non-carriers of the ε4 allele); or (c) APOE ε4 status alone (i.e., ignoring ‘diagnosis’ as a variable). Sample means strictly based on the donor’s sex did not reveal any difference in either MAO-A or MAO-B activity. Unexpectedly, we found that cortical MAO-A and MAO-B activities were highly correlated in both males and females (if focussing strictly on the donor’s sex), while in the hippocampus, any correlation was lost in female samples. Stratifying for sex-by-APOE ε4 status revealed a strong correlation between cortical MAO-A and MAO-B activities in both non-carriers and carriers of the allele, but any correlation in hippocampal samples was lost in carriers of the allele. A diagnosis of AD disrupted the correlation between MAO-A and MAO-B activities in the hippocampus, but not the cortex. We observed a novel region-dependent co-regulation of MAO-A and MAO-B mRNAs (but not proteins), while a lack of correlation between MAO activities and the respective proteins corroborated previous reports. Overexpression of human APOE4 increased MAO activity (but not mRNA/protein) in C6 and in HT-22 cell cultures. We identified a novel co-regulation of MAO-A and MAO-B activities that is spared from any influence of risk factors for AD or AD itself in the cortex, but vulnerable to these same factors in the hippocampus. Sex- and region-dependent abilities to buffer influences on brain MAO activities could have significant bearing on ambiguous outcomes when monoaminergic systems are targeted in clinical populations.
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Affiliation(s)
- Maa O Quartey
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Jennifer N K Nyarko
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Paul R Pennington
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Ryan M Heistad
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada
| | - Paula C Klassen
- The Pharmacology-Physiology Honours Program, University of Saskatchewan, Saskatoon, SK, Canada
| | - Glen B Baker
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Darrell D Mousseau
- Cell Signalling Laboratory, Department of Psychiatry, University of Saskatchewan, Saskatoon, SK, Canada.,The Pharmacology-Physiology Honours Program, University of Saskatchewan, Saskatoon, SK, Canada
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