Browsing by Author "Zawia, Nasser H."

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    Early-life events may trigger biochemical pathways for Alzheimer's disease: the "LEARn" model
    (Springer-Verlag, 2008-12) Lahiri, Debomoy K.; Zawia, Nasser H.; Greig, Nigel H.; Sambamurti, Kumar; Maloney, Bryan; Department of Psychiatry, IU School of Medicine
    Alzheimer's disease (AD), the most common form of dementia among the elderly, manifests mostly late in adult life. However, it is presently unclear when the disease process starts and how long the pathobiochemical processes take to develop. Our goal is to address the timing and nature of triggers that lead to AD. To explain the etiology of AD, we have recently proposed a "Latent Early-life Associated Regulation" (LEARn) model, which postulates a latent expression of specific genes triggered at the developmental stage. This model integrates both the neuropathological features (e.g., amyloid-loaded plaques and tau-laden tangles) and environmental factors (e.g., diet, metal exposure, and hormones) associated with the disease. Environmental agents perturb gene regulation in a long-term fashion, beginning at early developmental stages, but these perturbations do not have pathological results until significantly later in life. The LEARn model operates through the regulatory region (promoter) of the gene and by affecting the methylation status within the promoter of specific genes.
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    Latent consequences of early-life lead (Pb) exposure and the future: Addressing the Pb crisis
    (Elsevier, 2018-09) Maloney, Bryan; Bayon, Baindu L.; Zawia, Nasser H.; Lahiri, Debomoy K.; Psychiatry, School of Medicine
    Background. The lead (Pb) exposure crisis in Flint, Michigan has passed from well-publicized event to a footnote, while its biological and social impact will linger for lifetimes. Interest in the “water crisis” has dropped to pre-event levels, which is neither appropriate nor safe. Flint’s exposure was severe, but it was not unique. Problematic Pb levels have also been found in schools and daycares in 42 states in the USA. The enormity of Pb exposure via municipal water systems requires multiple responses. Herein, we focus on addressing a possible answer to long-term sequelae of Pb exposure. We propose “4R’s” (remediation, renovation, reallocation, and research) against the Pb crisis that goes beyond a short-term fix. Remediation for affected individuals must continue to provide clean water and deal with both short and long-term effects of Pb exposure. Renovation of current water delivery systems, at both system-wide and individual site levels, is necessary. Reallocation of resources is needed to ensure these two responses occur and to get communities ready for potential sequelae of Pb exposure. Finally, properly focused research can track exposed individuals and illuminate latent (presumably epigenetic) results of Pb exposure and inform further resource reallocation. Conclusion. Motivation to act by not only the general public but also by scientific and medical leaders must be maintained beyond initial news cycle spikes and an annual follow-up story. Environmental impact of Pb contamination of drinking water goes beyond one exposure incident in an impoverished and forgotten Michigan city. Population effects must be addressed long-term and nationwide.
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    The LEARn model: an epigenetic explanation for idiopathic neurobiological disease
    (Nature Publishing group, 2009-11) Lahiri, Debomoy K.; Maloney, Bryan; Zawia, Nasser H.; Psychiatry, School of Medicine
    Neurobiological disorders have diverse manifestations and symptomology. Neurodegenerative disorders such as Alzheimer’s disease (AD) manifest late in life and are characterized by, among other symptoms, progressive loss of synaptic markers. Developmental disorders, such as autism spectrum, appear in childhood. Neuropsychiatric and affective disorders, such as schizophrenia and major depressive disorder, respectively, have broad ranges of age of onset and symptoms. However, all share uncertain etiologies, with opaque relationships between genes and environment. We propose a “Latent Early–life Associated Regulation” (LEARn) model, positing latent changes in expression of specific genes initially primed at the developmental stage of life. In this model, environmental agents epigenetically disturb gene regulation in a long–term fashion, beginning at early developmental stages, but these perturbations might not have pathological results until significantly later in life. The LEARn model operates through the regulatory region (promoter) of the gene, specifically through changes in methylation and oxidation status within the promoter of specific genes. The LEARn model combines genetic and environmental risk factors in an epigenetic pathway to explain the etiology of the most common, i.e., sporadic, forms of neurobiological disorders.
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    Lifespan profiles of Alzheimer's disease–associated genes and their products in monkeys and mice.
    (IOS, 2009) Dosunmu, Remi; Wu, Jinfang; Adwan, Lina; Maloney, Bryan; Basha, Md Riyaz; McPherson, Christopher A.; Harry, G. Jean; Rice, Deborah C.; Zawia, Nasser H.; Lahiri, Debomoy K.; Department of Psychiatry, IU School of Medicine
    Alzheimer's disease (AD) is characterized by plaques of amyloid–beta (Aβ) peptide, cleaved from amyloid–β precursor protein (AβPP). Our hypothesis is that lifespan profiles of AD-associated mRNA and protein levels in monkeys would differ from mice, and that differential lifespan expression profiles would be useful to understand human AD pathogenesis. We compared profiles of AβPP mRNA, AβPP protein, and Aβ levels in rodents and primates. We also tracked a transcriptional regulator of the AβPP gene, specificity protein 1 (SP1), and the β amyloid precursor cleaving enzyme (BACE1). In mice, AβPP and Sp1 mRNA and their protein products were elevated late in life; Aβ levels declined in old age. In monkeys, Sp1, AβPP, and BACE1 mRNA declined in old age, while protein products and Aβ levels rose. Proteolytic processing in both species did not match production of Aβ. In primates, AβPP and Sp1 mRNA levels coordinate, but an inverse relationship exists with corresponding protein products, as well as Aβ levels. Comparison of human DNA and mRNA sequences to monkey and mouse counterparts revealed structural features that may explain differences in transcriptional and translational processing. These findings are important for selecting appropriate models for AD and other age–related diseases.