Alzheimer Disease: Aliev G

Aliev G, Obrenovich ME, Reddy VP, Shenk JC, Moreira PI, Nunomura A, Zhu X, Smith MA, Perry G. · Department of Biology, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249, USA. · Mini Rev Med Chem. · Pubmed #18991755 No free full text.

Abstract: Alzheimer disease treatment has yet to yield a successful therapy that addresses the source of the damage found in brains. Of the varied proposed theories of AD etiology, reactive oxygen species (ROS) generation is cited as a common factor. Efforts to reduce the pathology associated with ROS via antioxidants therefore offer new hope to patients suffering from this devastative disease.

Moreira PI, Nunomura A, Nakamura M, Takeda A, Shenk JC, Aliev G, Smith MA, Perry G. · Center for Neuroscience and Cell Biology, Institute of Physiology-Faculty of Medicine, University of Coimbra, Coimbra, Portugal. · Free Radic Biol Med. · Pubmed #18258207 No free full text.

Abstract: Increasing evidence suggests that oxidative stress is intimately associated with Alzheimer disease pathophysiology. Nucleic acids (nuclear DNA, mitochondrial DNA, and RNA) are one of the several cellular macromolecules damaged by reactive oxygen species, particularly the hydroxyl radical. Because neurons are irreplaceable and survive as long as the organism does, they need elaborate defense mechanisms to ensure their longevity. In Alzheimer disease, however, an accumulation of nucleic acid oxidation is observed, indicating an increased level of oxidative stress and/or a decreased capacity to repair the nucleic acid damage. In this review, we present data supporting the notion that mitochondrial and metal abnormalities are key sources of oxidative stress in Alzheimer disease. Furthermore, we outline the mechanisms of nucleic acid oxidation and repair. Finally, evidence showing the occurrence of nucleic acid oxidation in Alzheimer disease will be discussed.

Zhu X, Smith MA, Honda K, Aliev G, Moreira PI, Nunomura A, Casadesus G, Harris PL, Siedlak SL, Perry G. · Department of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA. · J Neurol Sci. · Pubmed #17337008 links to  free full text

Abstract: Alzheimer disease and cerebrovascular dementia are two common causes of dementia and, by present diagnostic criteria, are mutually exclusive using vascular pathology as an arbitrary demarcation in differential diagnosis. However, evidence from epidemiological, neuropathological, clinical, pharmacological, and functional studies suggest considerable overlap in risk factors and pathological changes suggesting shared common pathogenic mechanisms between these two diseases such that vascular factors play a vital role in the pathogenesis of Alzheimer disease. A high energy demand and lack of an endogenous fuel reserve make the brain highly dependent upon a continuous blood supply where disruption of cerebral blood vessels and blood flow can have serious consequences on neural activities. Indeed, many studies implicate metabolic defects in Alzheimer disease, such a reduced brain metabolism is one of the best documented abnormalities in the disease. Notably, since endothelial reactive oxygen species such as nitric oxide act as vasodilators at low concentrations, increased production coupled with elevated reactive oxygen species scavenging of nitric oxide, can lead to reduced bioavailability of nitric oxide and increased oxidative stress that damage sensitive vascular cells. In this respect, we and others have demonstrated that oxidative stress is one of the earliest pathological changes in the brain of Alzheimer disease patients and plays a critical role in the vascular abnormalities underlying metabolic defects in Alzheimer disease. Here, we discuss vascular factors in relation to Alzheimer disease and review hypoperfusion as a potential cause by triggering mitochondrial dysfunction and increased oxidative stress initiating the pathogenic process.

Zhu X, Perry G, Moreira PI, Aliev G, Cash AD, Hirai K, Smith MA. · Department of Pathology, Case Western Reserve University, 2103 Cornell Road, Cleveland, Ohio 44106, USA. · J Alzheimers Dis. · Pubmed #16873962 No free full text.

Abstract: A number of mitochondrial and metabolic abnormalities were identified in the hippocampal neurons of Alzheimer disease compared to age-matched controls. Hippocampal neurons are the most vulnerable to disease-associated pathology (i.e., cell death and proteinaceous lesions) and contain numerous markers of oxidative stress. Interestingly we found that the levels of mitochondrial DNA and cytochrome oxidase-1 in these neurons are markedly increased compared with those of age-matched control brains, even though the number of mitochondria per neuron is decreased. We hypothesize that the increased levels of mitochondrial DNA and cytochrome oxidase-1 may reflect an attempt by oxidatively-challenged neurons to replicate mitochondria, albeit unsuccessfully, as a response to the energetic/oxidative stress. Indeed, in this context, numerous signs of mitosis are observed in pyramidal neurons. Mitotic signals that promote cell cycle re-entry might be expected to also signal the synthesis of new mitochondria. Alternatively, these abnormalities may indicate altered turnover of mitochondrial components as a result of reduced degradation of mitochondrial byproducts or altered mitochondrial transport that redistributes mitochondrial DNA and cytochrome oxidase-1 to the cell body.

Moreira PI, Honda K, Liu Q, Santos MS, Oliveira CR, Aliev G, Nunomura A, Zhu X, Smith MA, Perry G. · Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA. · Curr Alzheimer Res. · Pubmed #16248845 No free full text.

Abstract: The complex nature and genesis of oxidative damage in Alzheimer disease can be partly answered by mitochondrial and redox-active metal abnormalities. By releasing high levels of hydrogen peroxide, dysfunctional mitochondria propagate a series of interactions between redox-active metals and oxidative response elements. In the initial phase of disease development, amyloid-beta deposition and hyperphosphorylated tau may function as compensatory responses and downstream adaptations to ensure that neuronal cells do not succumb to oxidative injuries. However, during the progression of the disease, the antioxidant activity of both agents evolves into pro-oxidant activity representing a typical gain-of-function transformation, which can result from an increase in reactive species and a decrease in clearance mechanisms.

Moreira PI, Smith MA, Zhu X, Honda K, Lee HG, Aliev G, Perry G. · Institute of Pathology, Case Western Research University, Cleveland, OH 44106, USA. · Drug News Perspect. · Pubmed #15753972 No free full text.

Abstract: Oxidative stress is a key factor involved in the development and progression of Alzheimer's disease, and it is well documented that free radical oxidative damage, particularly of neuronal lipids, proteins, nucleic acids and sugars, is extensive in brains of Alzheimer's disease patients. However, oxidative stress may elicit compensatory responses and downstream adaptations such as amyloid-beta deposition and neurofibrillary tangle formation, which may function as "shields" to ensure that neuronal cells do not succumb to oxidative injuries. Although during the past several years our understanding of the mechanisms leading to neuronal damage and death in the course of Alzheimer's disease has improved significantly, we have not found an effective therapeutic to fight this devastating disorder. However, the results obtained in clinical trials with antioxidants are promising and propel us in the search of new and more effective antioxidant therapies.

Zhu X, Smith MA, Perry G, Aliev G. · Institute of Pathology, Case Western Reserve University, Cleveland, Ohio, USA. · Am J Alzheimers Dis Other Demen. · Pubmed #15633943 No free full text.

Abstract: Mitochondrial dysfunction and free radical-induced oxidative damage have been implicated in the pathogenesis of several different neurodegenerative diseases such as Parkinson disease (PD), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and Alzheimer's disease (AD). The defective adenosine triphosphate (ATP) production and increased oxygen radicals may induce mitochondria-dependent cell death because damaged mitochondria are unable to maintain the energy demands of the cell. The role of vascular hypoperfusion-induced mitochondria failure in the pathogenesis of AD now has been widely accepted. However, the exact cellular mechanisms behind vascular lesions and their relation to oxidative stress markers identified by RNA oxidation, lipid peroxidation, or mitochondrial DNA (mtDNA) deletion remain unknown. Future studies comparing the spectrum of mitochondrial damage and the relationship to oxidative stress-induced damage during the aging process or, more importantly, during the maturation of AD pathology are warranted.

Moreira PI, Siedlak SL, Aliev G, Zhu X, Cash AD, Smith MA, Perry G. · Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA. · J Neural Transm. · Pubmed #15583960 No free full text.

Abstract: Oxidative damage of biological macromolecules is a hallmark of most neurodegenerative disorders such as Alzheimer, Parkinson and diffuse Lewy body diseases. Another important phenomenon involved in these disorders is the alteration of iron and copper homeostasis. Data from the literature support the involvement of metal homeostasis in mitochondrial dysfunction, protein alterations and nucleic acid damage which are relevant in brain function and consequently, in the development of neurodegenerative disorders. Although alterations in transition metal homeostasis, redox activity, and localization are well documented, it must be determined how alterations of specific copper- and iron-containing metalloenzymes are also involved in Alzheimer disease. The clarification of these phenomena can open a new window for understanding the mechanisms underlying neurodegeneration and, consequently, for the development of new therapeutic strategies such as gene therapy and new pharmaceutical formulations with antioxidant and chelating properties.

Seyidova D, Aliyev A, Rzayev N, Obrenovich M, Lamb BT, Smith MA, de la Torre JC, Perry G, Aliev G. · Microscopy Research Center, Institute of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA. · In Vivo. · Pubmed #15341188 No free full text.

Abstract: Nitric oxide (NO) is a key bioregulatory active molecule in the cardiovascular, immune and nervous systems, synthesized through converting L-arginine to L-citrulline by NO synthase (NOS). Research exploration supports the theory that this molecule appears to be one of the key factors for the disruption of normal brain homeostasis, which causes the development of brain lesions and pathology such as in Alzheimer's disease (AD). Especially the vascular content of NO activity appears to be a major contributor to this pathology before the overexpression of NOS activity in other brain cellullar compartments develop. We theorize that pharmacological intervention using NO donors and/or NO suppressors should delay or minimize brain lesion development and further progression of brain pathology and dementia.

Aliyev A, Seyidova D, Rzayev N, Obrenovich ME, Lamb BT, Chen SG, Smith MA, Perry G, de la Torre JC, Aliev G. · Microscopy Research Center, Case Western Reserve University, Cleveland, OH 44106, USA. · Neurol Res. · Pubmed #15265272 No free full text.

Abstract: Nitric oxide (NO) is a short-life key bioregulatory active molecule in the cardiovascular, immune and nervous systems. NO is synthesized by converting L-arginine to L-citrulline by enzymes called NO synthase (NOS). The growing body of evidence strongly supports the theory that this molecule appears to be one of the key targets for the disruption of normal brain homeostasis, which causes the development of brain lesions and pathology such as in Alzheimer's disease (AD) or other related dementia. The vascular content of NO activity appears especially to be a main contributor to this pathology before the over-expression of other NOS isoforms activity in a different brain cellular compartment. We speculate that pharmacological intervention using NO donors and/or NO suppressors will be able to delay or minimize the development of brain pathology and further progression of mental retardation.

Casadesus G, Smith MA, Zhu X, Aliev G, Cash AD, Honda K, Petersen RB, Perry G. · Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA. · J Alzheimers Dis. · Pubmed #15096700 No free full text.

Abstract: Free radical formation, abnormalities in iron and copper distribution, and metal-catalyzed oxidation have all been noted in Alzheimer disease and are thought to play an important role in disease pathogenesis. Metal-catalyzed hydroxyl radical formation results in damage to every category of macromolecule found in the vulnerable neuronal populations in Alzheimer disease. In fact, redox activity resides within the cytosol of vulnerable neurons. Since oxidative damage represents one of the earliest pathological changes in Alzheimer disease, it is likely that aberrant redox activity is among the earliest changes in the transition to the disease state. In this review, we consider the wealth of evidence implicating a central role for metals in Alzheimer disease.

Aliev G, Smith MA, Obrenovich ME, de la Torre JC, Perry G. · The Microscopy Research Center and Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland OH 44106, USA. · Neurotox Res. · Pubmed #14715433 No free full text.

Abstract: Chronic vascular hypoperfusion induces oxidative stress and brain energy failure, and leads to neuronal death, which manifests as cognitive impairment and the development of brain pathology as in Alzheimer disease (AD). It is becoming more widely accepted that AD is characterized by impairments in energy metabolism. We hypothesize that hypoperfusion-induced mitochondrial failure plays a central role in the generation of reactive oxygen species, resulting in oxidative damage to brain cellular compartments, especially in the vascular endothelium and neuronal cell bodies in AD. All of these changes have been found to occur before pathology and coexist during the progression of AD. In this review we have summarized recent evidence and our own knowledge regarding the relationship between the hypoperfusion-induced vascular damage that initiates oxidative stress and mitochondrial abnormalities that appear to be a key target for the development of AD pathology. Future investigations into both the mechanisms behind amyloid beta (Abeta) deposition and the possible accelerating effects of environmental factors, such as chronic hypoxia/reperfusion may open the door for effective pharmacological treatments of AD. We hypothesize that an imbalance between endothelium derived vasoconstrictors and vasodilators, along with an antioxidant system deficiency and mitochondria lesions are prominent in AD. Future studies examining the importance of mitochondrial pathophysiology in different brain cellular compartments may provide insight not only into neurodegenerative and/or cerebrovascular disease pathobiology but may also provide targets for treating these conditions.

Lee HG, Petersen RB, Zhu X, Honda K, Aliev G, Smith MA, Perry G. · Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA. · Brain Pathol. · Pubmed #14655766 No free full text.

Abstract: Protein aggregation and misfolding characterize most age-related neurodegenerative diseases including Alzheimer, Parkinson and Huntington diseases. Protein aggregation has generally been assumed to be responsible for neurodegeneration in these disorders due to association and genetics. However, protein aggregation may, in fact, be an attempt to protect neurons from the stress resulting from the disease etiology. In this review, we weigh the evidence of whether removal of amyloids, aggregates and neuronal inclusions represent a reasonable strategy for protecting neurons.

Perry G, Nunomura A, Raina AK, Aliev G, Siedlak SL, Harris PL, Casadesus G, Petersen RB, Bligh-Glover W, Balraj E, Petot GJ, Smith MA. · Department of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA. · Neurochem Res. · Pubmed #14570400 No free full text.

Abstract: Most studies of Alzheimer's disease (AD) have focused on a single precipitating alteration as the etiological event rather than global changes closely linked to aging. Recent evidence suggests that the most significant of these global changes are metabolic. Here we present data indicating that metabolic rate, nutrition, and neuronal size are all early indicators of AD. Understanding the cellular and molecular basis for these changes may open a new dimension to understanding AD.

Perry G, Nunomura A, Cash AD, Taddeo MA, Hirai K, Aliev G, Avila J, Wataya T, Shimohama S, Atwood CS, Smith MA. · Institute of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA. · J Neural Transm Suppl. · Pubmed #12456052 No free full text.

Abstract: Over the past decade, oxidative stress has been established as the earliest cytological feature of Alzheimer disease and an attractive therapeutic target. The major challenges now are establishing the source of the reactive oxygen and what oxidative stress tells us about the etiology of Alzheimer disease. These are complex issues since a variety of enzymatic and non-enzymatic processes are involved in reactive oxygen formation and damage to macromolecules. In this review, we consider disease mechanisms that show the greatest promise for future research.

Perry G, Nunomura A, Hirai K, Zhu X, Pérez M, Avila J, Castellani RJ, Atwood CS, Aliev G, Sayre LM, Takeda A, Smith MA. · Institute of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA. · Free Radic Biol Med. · Pubmed #12446204 No free full text.

Abstract: In less than a decade, beginning with the demonstration by Floyd, Stadtman, Markesbery et al. of increased reactive carbonyls in the brains of patients with Alzheimer's disease (AD), oxidative damage has been established as a feature of the disease. Here, we review the types of oxidative damage seen in AD, sites involved, possible origin, relationship to lesions, and compensatory changes, and we also consider other neurodegenerative diseases where oxidative stress has been implicated. Although much data remain to be collected, the broad spectrum of changes found in AD are only seen, albeit to a lesser extent, in normal aging with other neurodegenerative diseases showing distinct spectrums of change.

Castellani R, Hirai K, Aliev G, Drew KL, Nunomura A, Takeda A, Cash AD, Obrenovich ME, Perry G, Smith MA. · Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA. · J Neurosci Res. · Pubmed #12391597 No free full text.

Abstract: Abnormalities in mitochondrial function relate to the spectrum of pathological changes seen in Alzheimer's disease. Here we review the causes and consequences of mitochondrial disturbances in Alzheimer's disease as well as how this information might impact on therapeutic approaches to this disease.

Aliev G, Smith MA, Seyidov D, Neal ML, Lamb BT, Nunomura A, Gasimov EK, Vinters HV, Perry G, LaManna JC, Friedland RP. · Electron Microscopy Center, and Department of Anatomy, Case Western Reserve University, School of Medicine and University Hospital of the Cleveland, OH 44106-4938, USA. · Brain Pathol. · Pubmed #11770899 No free full text.

Abstract: Alzheimer's disease (AD) and stroke are two leading causes of age-associated dementia. A rapidly growing body of evidence indicates that increased oxidative stress from reactive oxygen radicals is associated with the aging process and age-related degenerative disorders such as atherosclerosis, ischemia/reperfusion, arthritis, stroke, and neurodegenerative diseases. New evidence has also indicated that vascular lesions are a key factor in the development of AD. This idea is based on a positive correlation between AD and cardiovascular and cerebrovascular diseases such as arterio- and atherosclerosis and ischemia/reperfusion injury. In this review we consider recent evidence supporting the existence of an intimate relationship between oxidative stress and vascular lesions in the pathobiology of AD. We also consider the opportunities for therapeutic interventions based on the molecular pathways involved with these causal relationships.

Perry G, Nunomura A, Hirai K, Takeda A, Aliev G, Smith MA. · Institute of Pathology, Case Western Reserve University, 2085 Adelbert Road, Cleveland, USA. · Int J Dev Neurosci. · Pubmed #10817925 No free full text.

Abstract: Cell bodies of neurons at risk of death in Alzheimer disease have increased lipid peroxidation, nitration, free carbonyls, and nucleic acid oxidation. These oxidative changes are uniform among neurons and are seen whether or not the neurons display neurofibrillary tangles and, in fact, are acutally reduced in the latter case. In consideration of this localization of damage, in this review, we provide a summary of recent work demonstrating some key abnormalities that may initiate and promote neuronal oxidatave damage.

Obrenovich ME, Morales LA, Cobb CJ, Shenk JC, Méndez GM, Fischbach K, Smith MA, Qasimov EK, Perry G, Aliev G. · Department of Pathology, Case Western Reserve University, Cleveland, OH, USA. · J Cell Mol Med. · Pubmed #19292735 No free full text.

Abstract: Alzheimer disease (AD) and stroke are two leading causes of age-associated dementia. Increasing evidence points to vascular damage as an early contributor to the development of AD and AD-like pathology. In this review, we discuss the role of G protein-coupled receptor kinase 2 (GRK2) as it relates to individuals affected by AD and how the cardiovasculature plays a role in AD pathogenesis. The possible involvement of GRKs in AD pathogenesis is an interesting notion, which may help bridge the gap in our understanding of the heartbrain connection in relation to neurovisceral damage and vascular complications in AD, since kinases of this family are known to regulate numerous receptor functions both in the brain, myocardium, and elsewhere. The aim of this review is to discuss our findings of overexpression of GRK2 in the context of the early pathogenesis of AD, because increased levels of GRK2 immunoreactivity were found in vulnerable neurons of AD patients as well as in a two-vessel occlusion (2-VO) mammalian model of ischaemia. Also, we consider the consequences for this overexpression as a loss of G-protein coupled receptor (GPCR) regulation, as well as suggest a potential role for GPCRs and GRKs in a unifying theory of AD pathogenesis, particularly in the context of cerebrovascular disease. We synthesize this newer information and attempt to put it into context with GRKs as regulators of diverse physiological cellular functions that could be appropriate targets for future pharmacological intervention.

Aliev G, Gasimov E, Obrenovich ME, Fischbach K, Shenk JC, Smith MA, Perry G. · Department of Biology, University of Texas at San Antonio, San Antonio, Texas 78249-1664, USA. · Vasc Health Risk Manag. · Pubmed #18827923 links to  free full text

Abstract: The pathogenesis that is primarily responsible for Alzheimer's disease (AD) and cerebrovascular accidents (CVA) appears to involve chronic hypoperfusion. We studied the ultrastructural features of vascular lesions and mitochondria in brain vascular wall cells from human AD biopsy samples and two transgenic mouse models of AD, yeast artificial chromosome (YAC) and C57B6/SJL Tg (+), which overexpress human amyloid beta precursor protein (AbetaPP). In situ hybridization using probes for normal and 5 kb deleted human and mouse mitochondrial DNA (mtDNA) was performed along with immunocytochemistry using antibodies against the Abeta peptide processed from AbetaPP, 8-hydroxy-2'-guanosine (8OHG), and cytochrome c oxidase (COX). More amyloid deposition, oxidative stress markers as well as mitochondrial DNA deletions and structural abnormalities were present in the vascular walls of the human AD samples and the AbetaPP-YAC and C57B6/SJL Tg (+) transgenic mice compared to age-matched controls. Ultrastructural damage in perivascular cells highly correlated with endothelial lesions in all samples. Therefore, pharmacological interventions, directed at correcting the chronic hypoperfusion state, may change the natural course of the development of dementing neurodegeneration.

Moreira PI, Siedlak SL, Wang X, Santos MS, Oliveira CR, Tabaton M, Nunomura A, Szweda LI, Aliev G, Smith MA, Zhu X, Perry G. · Department of Pathology, Case Western Reserve University, Cleveland, Ohio, USA. · Autophagy. · Pubmed #17786024 No free full text.

Abstract: Extensive literature exists supporting a role for mitochondrial dysfunction and oxidative damage in the pathogenesis of Alzheimer disease. Mitochondria are a major source of intracellular reactive oxygen species and are themselves particularly vulnerable to oxidative stress. It has been recently shown that the immunoreactivity of lipoic acid and cytochrome oxidase-1, two mitochondrial markers, is increased in the cytoplasm of pyramidal neurons in Alzheimer disease cases compared with controls. Furthermore, lipoic acid was found to be strongly associated with granular structures and, by ultrastructure analysis, shown to be localized in mitochondria, cytosol and, importantly, in organelles identified as autophagic vacuoles. Lipoic acid was also found associated with the electron dense core of lipofuscin in the brains of Alzheimer disease cases but not in controls, whereas cytochrome oxidase-1 immunoreactivity was limited to mitochondria and cytosol in both Alzheimer and control cases. These data suggest that mitochondria are key targets of increased autophagic degradation in Alzheimer disease. The study of autophagy in Alzheimer disease could clarify the mechanisms underlying this neurodegenerative disorder and, eventually, help in the development of new therapeutic strategies.

Moreira PI, Siedlak SL, Wang X, Santos MS, Oliveira CR, Tabaton M, Nunomura A, Szweda LI, Aliev G, Smith MA, Zhu X, Perry G. · Department of Pathology, Case Western Reserve University, Cleveland, Ohio, USA. · J Neuropathol Exp Neurol. · Pubmed #17549012 No free full text.

Abstract: Mitochondrial abnormalities are prominent in Alzheimer disease. In this study, 2 mitochondrial markers, cytochrome oxidase-1 and lipoic acid, a sulfur-containing cofactor required for the activity of several mitochondrial enzyme complexes, were compared using light and electron microscopic analyses and immunoblot assays. Both lipoic acid and cytochrome oxidase-1 immunoreactivity are increased in the cytoplasm of pyramidal neurons in Alzheimer disease compared with control cases. Of significance, lipoic acid was found to be strongly associated with granular structures, and ultrastructure analysis showed localization to mitochondria, cytosol, and, importantly, in organelles identified as autophagic vacuoles and lipofuscin in Alzheimer disease but not control cases. Cytochrome oxidase-1 immunoreactivity was limited to mitochondria and cytosol in both Alzheimer and control cases. These data suggest that mitochondria are key targets of increased autophagic degradation in Alzheimer disease. Whether increased autophagocytosis is a consequence of an increased turnover of mitochondria or whether the mitochondria in Alzheimer disease are more susceptible to autophagy remains to be resolved.

Obrenovich ME, Smith MA, Siedlak SL, Chen SG, de la Torre JC, Perry G, Aliev G. · Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA. · Neurotox Res. · Pubmed #17000469 No free full text.

Abstract: Heterotrimeric guanine nucleotide-binding (G) protein-coupled receptor kinases (GRKs) are cytosolic proteins that are known to contribute to the adaptation of the heptahelical G protein-coupled receptors (GPCRs) and to regulate downstream signals through these receptors. GPCRs mediate the action of messengers that are key modulators of cardiac and vascular cell function, such as growth and differentiation. GRKs are members of a multigene family, which are classified into three subfamilies and are found in cardiac, vascular and cerebral tissues. Increasing evidence strongly supports the hypothesis that vascular damage is an early contributor to the development of Alzheimer disease (AD) and/or other pathology that can mimic human AD. Based on this hypothesis, and since kinases of this family are known to regulate numerous receptor functions both in the brain, myocardium and elsewhere, we explored cellular and subcellular localization by immunoreactivity of G protein-coupled receptor kinase 2 (GRK2), also known as beta-adrenergic receptor kinase-1(betaARK1), in the early pathogenesis of AD and in ischemia reperfusion injury models of brain hypoperfusion. In the present study, we used the two-vessel carotid artery occlusion model, namely the 2-VO system that results in chronic brain hypoperfusion (CBH) and mimics mild cognitive impairment (MCI) and vascular changes in AD pathology. Our findings demonstrate the early overexpression of GRK2 member kinase in the cerebrovasculature, especially endothelial cells (EC) following CBH, as well as in select cells from human AD tissue. We found a significant increase in GRK2 immunoreactivity in the EC of AD patients and after CBH, which preceded any amyloid deposition. Since GRK2 activity is associated with certain compensatory changes in brain cellular compartments and in ischemic cardiac tissue, our findings suggest that chronic hypoperfusion initiates oxidative stress in these conditions and appears to be the main initiating injury stimulus for disruption of brain and cerebrovascular homeostasis and metabolism.

Aliyev A, Chen SG, Seyidova D, Smith MA, Perry G, de la Torre J, Aliev G. · The Microscopy Research Center, Case Western Reserve University, Cleveland, OH 44106, USA. · J Neurol Sci. · Pubmed #15760652 No free full text.

Abstract: The pathogenesis, which is primarily responsible for Alzheimer's disease (AD) and cerebrovascular accidents (CVA), seems to involve chronic hypoperfusion. The role of hypoperfusion, as a key factor for vascular lesions that causes oxidative stress, appears to be widely accepted as an initiator of AD. Specifically, accumulated oxidative stress increases vascular endothelial permeability and promotes leukocyte adhesions, which is coupled with alterations in endothelial signal transduction and redox-regulated transcription factors. Based on these recent findings, we hypothesize that the cellular and molecular mechanisms by which hypoperfusion-induced reactive oxygen species (ROS) accumulation impairs endothelial barrier function and promotes leukocyte adhesion induces alterations in normal vascular function and results in the development of AD. We are theorizing that mitochondria play a key role in the generation of ROS, resulting in oxidative damage to neuronal cell bodies, as well as other cellular compartment in the AD brain. All of these changes have been found to accompany AD pathology. We have studied the ultrastructural features of vascular lesions and mitochondria in brain vascular wall cells from human AD, yeast artificial chromosome (YAC) and C57B6/SJL transgenic positive (Tg+) mice overexpressing amyloid beta precursor protein (AbetaPP). In situ hybridization using mitochondrial DNA (mtDNA) probes for human wild and 5 kb deleted types and mouse types was performed along with immunocytochemistry using antibodies against amyloid precursor protein (APP), 8-hydroxy-2'-guanosine (8-OHG) and cytochrome c oxidase (COX). There was a higher degree of amyloid deposition, overexpression of oxidative stress markers, mitochondria DNA deletion and mitochondrial structural abnormality in the vascular walls of the human AD, YAC and C57B6/SJL Tg (+) mice compared to age-matched controls. Therefore, selective pharmacological intervention, directed for abolishing the chronic hypoperfusion state, would possibly change the natural course of development of dementing neurodegeneration.