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York A, Everhart A, Vitek MP, Gottschalk KW, Colton CA. Metabolism-Based Gene Differences in Neurons Expressing Hyperphosphorylated AT8- Positive (AT8+) Tau in Alzheimer's Disease. ASN Neuro 2021; 13:17590914211019443. [PMID: 34121475 PMCID: PMC8207264 DOI: 10.1177/17590914211019443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Metabolic adaptations in the brain are critical to the establishment and maintenance of normal cellular functions and to the pathological responses to disease processes. Here, we have focused on specific metabolic pathways that are involved in immune-mediated neuronal processes in brain using isolated neurons derived from human autopsy brain sections of normal individuals and individuals diagnosed as Alzheimer's disease (AD). Laser capture microscopy was used to select specific cell types in immune-stained thin brain sections followed by NanoString technology to identify and quantify differences in mRNA levels between age-matched control and AD neuronal samples. Comparisons were also made between neurons isolated from AD brain sections expressing pathogenic hyperphosphorylated AT8- positive (AT8+) tau and non-AT8+ AD neurons using double labeling techniques. The mRNA expression data showed unique patterns of metabolic pathway expression between the subtypes of captured neurons that involved membrane based solute transporters, redox factors, and arginine and methionine metabolic pathways. We also identified the expression levels of a novel metabolic gene, Radical-S-Adenosyl Domain1 (RSAD1) and its corresponding protein, Rsad1, that impact methionine usage and radical based reactions. Immunohistochemistry was used to identify specific protein expression levels and their cellular location in NeuN+ and AT8+ neurons. APOE4 vs APOE3 genotype-specific and sex-specific gene expression differences in these metabolic pathways were also observed when comparing neurons from individuals with AD to age-matched individuals.
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Affiliation(s)
- Audra York
- Division of Translational Brain Sciences, Department of Neurology, Duke University Medical Center, Durham, North Carolina, United States
| | - Angela Everhart
- Division of Translational Brain Sciences, Department of Neurology, Duke University Medical Center, Durham, North Carolina, United States
| | - Michael P Vitek
- Division of Translational Brain Sciences, Department of Neurology, Duke University Medical Center, Durham, North Carolina, United States
| | - Kirby W Gottschalk
- Division of Translational Brain Sciences, Department of Neurology, Duke University Medical Center, Durham, North Carolina, United States
| | - Carol A Colton
- Division of Translational Brain Sciences, Department of Neurology, Duke University Medical Center, Durham, North Carolina, United States
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Zheng R, da Rosa G, Dans PD, Peluffo RD. Molecular Determinants for Nitric Oxide Regulation of the Murine Cationic Amino Acid Transporter CAT-2A. Biochemistry 2020; 59:4225-4237. [PMID: 33135877 DOI: 10.1021/acs.biochem.0c00729] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cationic amino acid transporters (CATs) supply cells with essential and semiessential dibasic amino acids. Among them, l-arginine is the substrate for nitric oxide synthases (NOS) to produce nitric oxide (NO), a key signaling molecule and second messenger. In cardiac preparations, we showed that NO acutely and directly modulates transport activity by noncompetitively inhibiting these CATs. We hypothesize that this NO regulation occurs through modification of cysteine residues in CAT proteins. Homology modeling and a computational chemistry approach identified Cys347 as one of two putative targets for NO binding, of 15 Cys residues present in the low-affinity mouse CAT-2A (mCAT-2A). To test this prediction, mammalian cell lines overexpressing mCAT-2A were used for site-directed mutagenesis and uptake studies. When Cys347 was replaced with alanine (Cys347Ala), mCAT-2A became insensitive to inhibition by NO donors. In addition, the transport capacity of this variant decreased by >50% compared to that of the control, without affecting membrane expression levels or apparent affinities for the transported amino acids. Interestingly, replacing Cys347 with serine (Cys347Ser) restored uptake levels to those of the control while retaining NO insensitivity. Other Cys residues, when replaced with Ala, still produced a NO-sensitive CAT-2A. In cells co-expressing NOS and mCAT-2A, exposure to extracellular l-arginine inhibited the uptake activity of control mCAT-2A, via NO production, but not that of the Cys347Ser variant. Thus, the -SH moiety of Cys347 is largely responsible for mCAT-2A inhibition by NO. Because of the endogenous NO effect, this modulation is likely to be physiologically relevant and a potential intervention point for therapeutics.
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Affiliation(s)
- Ruifang Zheng
- Department of Pharmacology, Physiology and Neuroscience, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers, The State University of New Jersey, 185 South Orange Avenue, Newark, New Jersey 07103, United States
| | - Gabriela da Rosa
- Laboratory of Molecular Microbiology, DEPBIO, School of Sciences-School of Chemistry, Universidad de la República, 11400 Montevideo, Uruguay.,Functional Genomics Laboratory, Institut Pasteur of Montevideo, Mataojo 2020, CP, 11400 Montevideo, Uruguay.,Group of Biophysical Chemistry, Department of Biological Sciences, CENUR Litoral Norte, Universidad de la República, Rivera 1350, CP, 50000 Salto, Uruguay
| | - Pablo D Dans
- Functional Genomics Laboratory, Institut Pasteur of Montevideo, Mataojo 2020, CP, 11400 Montevideo, Uruguay.,Group of Biophysical Chemistry, Department of Biological Sciences, CENUR Litoral Norte, Universidad de la República, Rivera 1350, CP, 50000 Salto, Uruguay
| | - R Daniel Peluffo
- Department of Pharmacology, Physiology and Neuroscience, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers, The State University of New Jersey, 185 South Orange Avenue, Newark, New Jersey 07103, United States.,Group of Biophysical Chemistry, Department of Biological Sciences, CENUR Litoral Norte, Universidad de la República, Rivera 1350, CP, 50000 Salto, Uruguay
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