Search

A comprehensive focus on 4-hydroxynonenal (HNE) as candidate molecule in a variety of pathophysiological conditions occurring in humans is here provided. Despite an active, now well characterized, metabolism in most cells and tissues, HNE can be easily detected and quantified by means of several methods, although with different sensitivity. Measurements of HNE and/or stable metabolites in biological fluids are already applied as lipid peroxidation/oxidative stress markers in a huge number of human disease processes, often sustained by inflammatory reactions. A primary involvement of this aldehydic product of membrane lipid oxidation in inflammation-related events, as well as in regulation of cell proliferation and growth, in necrotic or apoptotic cell death, appears supported by its marked ability to modulate several major pathways of cell signaling and, consequently, gene expression. The actual knowledge of HNE reactivity, metabolism, signaling and modulatory effect in the various human organs should provide a solid background to the investigation of the aldehyde's contribution to the pathogenesis of human major chronic diseases and would likely promote advanced and oriented applications not only in diagnosis and prevention but also in molecular treatment of human diseases. © 2007 Wiley Periodicals, Inc. Med Res Rev, 28, No. 4, 569-631, 2008 [ABSTRACT FROM AUTHOR]

Advances in the understanding of AD pathogenesis have recently provided strong support for a modified Aβ protein cascade hypothesis, stating that several different Aβ assemblies contribute to the triggering of a complex pathological cascade leading to neurodegeneration. Both in vitro and in vivo, Aβ rapidly forms fibrils (fAβ), which are able to interact with various molecular partners, including proteins, lipids and proteoglycans. In a previous study aimed to identify some of these molecular partners of fAβ, we demonstrated that the GAPDH was specifically coprecipitated with fAβ. The aim of this study was to characterize this interaction. First, it was shown by TEM that synthetic GAPDH directly binds fAβ 1-42. Then rat synaptosomal proteins were purified and incubated with different forms of Aβ in various conditions, and the presence of GAPDH among the proteins coprecipitated with Aβ was studied by western blotting. Results showed that the interaction between GAPDH and fAβ 1-42 is nonionic, as is not impaired by increasing salt concentrations. GAPDH is coprecipitated not only by fAβ, but also by nonfibrillar forms of Aβ 1-42. The 41-42 Aβ sequence seems to be important in the interaction of GAPDH and Aβ, as more GAPDH was coprecipitated with fAβ 1-42 than with fAβ 1-40. GAPDH extracted from various subcellular fractions including mitochondria, was shown to interact with fAβ. Our data demonstrate a direct interaction between Aβ and GAPDH and support the possibility that this interaction has an important pathogenic role in AD. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The importance of translational control in cancer progression has been underscored by a number of recent studies. However, little is known how cancer cells maintain their high efficiency of translation. Here, we summarize studies that support the role of integrins in translational control, especially at the initiation step, and discuss the various mechanisms by which integrins regulate the recruitment of translational machinery. This review also examines the hypothesis that integrins contribute to various aspects of cancer progression such as proliferation, survival, angiogenesis, and invasion through translational control. Microsc. Res. Tech. 2008. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

In this study of a cohort of 33 young and middle-age adults (19-59 years) we report simultaneous measurements of normal age-related changes in the caudate nuclei volume, diffusion tensor metrics, and T2 relaxation time. Both the absolute caudate volume and its ratio relative to the total intracranial volume decreased rapidly with age in both men and women ( r = −0.55; P < 0.001). The fractional diffusion tensor anisotropy of the caudate nuclei increased with age in both males and females ( r = 0.48; P = 0.005). The corresponding age correlations of the caudate axial ( r = 0.17; P = 0.35), transverse ( r = −0.12; P = 0.50), mean diffusivities ( r = 0.018; P = 0.92), and T2 relaxation times ( r = 0.194; P = 0.28) were weaker and did not reach statistical significance ( P > 0.05). Our preliminary findings warrant further studies on the older and aging adults and indicate that caudate diffusion tensor imaging-derived metrics can be used as surrogates in modeling the neuronal substrates of gray matter atrophy. Magn Reson Med, 2007. © 2007 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Protein carbonylation induced by reactive carbonyl species (RCS) generated by peroxidation of polyunsaturated fatty acids plays a significant role in the etiology and/or progression of several human diseases, such as cardiovascular (e.g., atherosclerosis, long-term complications of diabetes) and neurodegenerative diseases (e.g., Alzheimer's disease, Parkinson's disease, and cerebral ischemia). Most of the biological effects of intermediate RCS, mainly α,β-unsaturated aldehydes, di-aldehydes, and keto-aldehydes, are due to their capacity to react with the nucleophilic sites of proteins, forming advanced lipoxidation end-products (ALEs). Because of the emerging deleterious role of RCS/protein adducts in several human diseases, different potential therapeutic strategies have been developed in the last few years. This review sheds focus on fundamental studies on lipid-derived RCS generation, their biological effects, and their reactivity with proteins, with particular emphasis to 4-hydroxy- trans-2-nonenal (HNE)-, acrolein (ACR)-, malondialdehyde (MDA)-, and glyoxal (GO)-modified proteins. It also discusses the recently developed pharmacological approaches for the management of chronic diseases in which oxidative stress and RCS formation are massively involved. Inhibition of ALE formation, based on carbonyl-sequestering agents, seems to be the most promising pharmacological tool and is reviewed in detail. © 2006 Wiley Periodicals, Inc. Med Res Rev, 27, No. 6, 817-868, 2007 [ABSTRACT FROM AUTHOR]

Background: The higher incidence of smoking among alcoholic subjects suggests the presence of common molecular mechanisms underlying nicotine and alcohol use and abuse. However, these mechanisms are largely unknown. By using cultured fetal mouse cortical neurons as a model system, we sought to identify genes and pathways that are modulated in the cells by ethanol, nicotine, or both. Methods: Primary cerebral cortical cultures were prepared from the brains of 14-day-old C57BL/6 mouse fetuses and exposed to ethanol (75 mM), nicotine (0.1 mM), or both for 5 consecutive days. A homeostatic pathway-focused microarray consisting of 638 sequence-verified genes was used to measure transcripts differentially regulated by ethanol, nicotine, or both in 5 drug-treated cortical neuron samples and 5 control samples. Quantitative real-time reverse transcriptase-polymerase chain reaction analysis was used to verify the mRNA expression levels of genes of interest detected from the microarray experiments. Results: Through a pathway-focused cDNA microarray and balanced experimental design, we identified 65, 111, and 81 significantly regulated genes in the ethanol, nicotine, and ethanol/nicotine-treated neurons, respectively. Of them, the genes of Akt2, Nsg1, Pdgfa, Pfn1, Rbbp7, and Tcfeb were comodulated. The genes differentially expressed in 1 or more treatment groups could be classified into 4 major clusters, with each cluster consisting of genes involved in different biological processes. The platelet-derived growth factor (PDGF) signaling pathway was significantly regulated by all 3 treatments, but by different mechanisms, which may lead to different cellular consequences. Conclusions: Our results indicate that the PDGF pathway represents one of the major biochemical mechanisms in the cellular and molecular responses to each drug in cortical neurons. Finally, we demonstrated that the pathway-focused microarray system used in the present study is a valuable tool for dissecting the mechanisms of complex signaling pathways such as the PDGF pathway. [ABSTRACT FROM AUTHOR]

Mitochondrial disorders share common cellular consequences: (1) decreased ATP production; (2) increased reliance on alternative anaerobic energy sources; and (3) increased production of reactive oxygen species. The purpose of the present study was to determine the effect of a combination therapy (creatine monohydrate, coenzyme Q10, and lipoic acid to target the above-mentioned cellular consequences) on several outcome variables using a randomized, double-blind, placebo-controlled, crossover study design in patients with mitochondrial cytopathies. Three patients had mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), four had mitochondrial DNA deletions (three patients with chronic progressive external ophthalmoplegia and one with Kearns-Sayre syndrome), and nine had a variety of other mitochondrial diseases not falling into the two former groups. The combination therapy resulted in lower resting plasma lactate and urinary 8-isoprostanes, as well as attenuation of the decline in peak ankle dorsiflexion strength in all patient groups, whereas higher fat-free mass was observed only in the MELAS group. Together, these results suggest that combination therapies targeting multiple final common pathways of mitochondrial dysfunction favorably influence surrogate markers of cellular energy dysfunction. Future studies with larger sample sizes in relatively homogeneous groups will be required to determine whether such combination therapies influence function and quality of life. Muscle Nerve, 2006 [ABSTRACT FROM AUTHOR]

Chronic melatonin exposure produces microtubule rearrangements in Chinese hamster ovary (CHO) cells expressing the human MT1 melatonin receptor while at the same time desensitizing MT1 receptors. Because microtubule rearrangements parallel MT1 receptor desensitization, we tested whether microtubules modulate receptor responsiveness. We determined whether depolymerization of microtubules by Colcemid, which prevents melatonin-induced outgrowths in MT1-expressing CHO cells, also prevents MT1 receptor desensitization by affecting G α-GTP exchange on G-proteins. In this study, we found that depolymerization of microtubules in MT1 receptor expressing cells, prevented melatonin-induced receptor desensitization reflected by an increase in the number of high potency sites when compared with melatonin-treated cells. Further examination of the mechanism(s) underlying this desensitization suggested that these effects occurred at the level of G-proteins. Depolymerization of microtubules during melatonin-induced desensitization, attenuated forskolin-induced cAMP accumulation, the opposite of which usually occurs following melatonin exposure alone. Concomitant to this attenuation in the forskolin response was a reduction in the amount of Gi α protein coupled to MT1 receptors and an increase in [32P] azidoanilido GTP incorporation into Gi proteins. These data are consistent with the findings that microtubule depolymerization did not affect MT1/Gq coupling nor did it affect melatonin-induced phosphoinositide hydrolysis following melatonin exposure. However, interestingly, microtubule depolymerization enhanced melatonin-induced protein kinase C activation that was blocked in the presence of pertussis toxin. These data demonstrate that microtubule dynamics can modulate melatonin receptor function through their actions on Gi proteins and impact on downstream signaling cascades. [ABSTRACT FROM AUTHOR]

The cellular complexity of the brain (some estimate that there are up to 103 different cell types) is exceeded by the synaptic complexity, with each of the ∼1011 neurons in the brain having around 103–104 synapses. Proteomic studies of the synapse have revealed that the postsynaptic density is the most complex multiprotein structure yet identified, with ∼103 different proteins. Such studies, however, use brain tissue with many different regions and therefore different cell types, and there is clear potential for heterogeneity of protein content at different synapses within and between brain regions. Although large-scale mRNA-based assays are in progress to map this sort of complexity at the cellular level, and indeed all brain-expressed genes, analysis of protein distribution (at synapses and other structures) is still in the very early stages. We review existing large-scale protein expression studies and the specific technical obstacles that need to be overcome before applying the scaling used in nucleic acid based approaches. [ABSTRACT FROM AUTHOR]

Growing evidence suggests an involvement of iron in the pathophysiology of neurodegenerative diseases. Several of the diseases are associated with parkinsonian syndromes, induced by degeneration of basal ganglia regions that contain the highest amount of iron within the brain. The group of neurodegenerative disorders associated with parkinsonian syndromes with increased brain iron content can be devided into two groups: (1) parkinsonian syndromes associated with brain iron accumulation, including Parkinson's disease, diffuse Lewy body disease, parkinsonian type of multiple system atrophy, progressive supranuclear palsy, corticobasal ganglionic degeneration, and Westphal variant of Huntington's disease; and (2) monogenetically caused disturbances of brain iron metabolism associated with parkinsonian syndromes, including aceruloplasminemia, hereditary ferritinopathies affecting the basal ganglia, and panthotenate kinase associated neurodegeneration type 2. Although it is still a matter of debate whether iron accumulation is a primary cause or secondary event in the first group, there is no doubt that iron-induced oxidative stress contributes to neurodegeneration. Parallels concerning pathophysiological as well as clinical aspects can be drawn between disorders of both groups. Results from animal models and reduction of iron overload combined with at least partial relief of symptoms by application of iron chelators in patients of the second group give hope that targeting the iron overload might be one possibility to slow down the neurodegenerative cascade also in the first group of inevitably progressive neurodegenerative disorders. © 2006 Movement Disorder Society [ABSTRACT FROM AUTHOR]

Wellington CL. Cholesterol at the crossroads: Alzheimer's disease and lipid metabolism. Alzheimer's Disease (AD) is a devastating disease that affects millions of elderly persons. Despite years of intense investigations, genetic risk factors that affect the majority of AD cases have yet to be determined. Recent studies suggest that cholesterol metabolism has integral part in AD pathogenesis, suggesting that genes that regulate lipid metabolism may also play roles in AD. This review will first describe emerging evidence that links cholesterol to the mechanisms thought to underlie AD. Based on this rationale, candidate genes located in regions implicated in AD that have roles in lipid metabolism will then be discussed. [ABSTRACT FROM AUTHOR]

Summary. Hepatitis C virus (HCV) infection is the most common cause of chronic hepatitis, which frequently progresses to hepatocellular carcinoma. The pathogenesis of its persistent infection and tumour progression has not been fully characterized yet. The RCK gene was previously cloned at the breakpoint of the t(11;14)(q23;q32) chromosome translocation observed in human B-cell lymphoma cell line RC-K8. The RCK protein, rck/p54, which is a 54-kDa cytoplasmic protein belonging to the DEAD box/RNA helicase family, is considered to facilitate the translation of mRNA(s) of genes for cell proliferation and malignant transformation not only in B-cell lymphomas having the t(11;14) translocation but also in other solid tumours. The aim of this work was to examine the involvement of rck/p54 in carcinogenesis of hepatocellular carcinoma from HCV-related chronic hepatitis. We examined the expression of rck/p54 in 29 cases of HCV-related chronic hepatitis and eight cases of hepatocellular carcinoma by immunohistochemistry and Western blot analysis. Twenty-six of 29 cases with HCV-related chronic hepatitis and all cases with hepatocellular carcinoma tested overexpressed rck/p54 protein. The expression of rck/p54 was lowered by treatment with IFN-α in two cases who showed the decrease in HCV RNA levels. These findings suggest that rck/p54 protein is possibly involved in the replication of HCV genomes in hepatocytes and in tumourigenesis of hepatocellular carcinomas. [ABSTRACT FROM AUTHOR]

Studies in vitro have shown that phosphorylated translation initiation factor 2α (TIF 2α) may have several functions, including regulation of protein synthesis, control of cell death and procurement of resistance to oxidative stress in nerve cells. These properties may have implications in certain human neurodegenerative diseases, such as Alzheimer's disease (AD) and Creutzfeldt–Jakob's disease (CJD), in which oxidative stress appears to be involved in the process of neurodegeneration and neurone death. Single and double-labelling immunohistochemistry to phosphorylated TIF 2α, phosphorylated SAPK/JNK, phosphorylated p38, tau , Cu/Zn superoxide dismutase 1 (SOD 1) and cleaved caspase-3 (17 kDa), and in situ end-labelling of nuclear DNA fragmentation, was carried out in postmortem samples of 10 patients with AD (stages III and VI of Braak and Braak), seven patients with CJD (five cases with methionine/methionine and two cases with methionine/valine at the codon 129 of the PrP gene) and eight age-matched controls. No phosphorylated TIF 2α immunoreactivity was found in control brains, but strong phosphorylated TIF 2α expression was observed in subpopulations of neurones bearing neurofibrillary tangles (NFTs) or pretangles in the hippocampus, entorhinal cortex and isocortex in AD. Phosphorylated TIF 2α is restricted to neurones with abnormal tau deposition, but only approximately 80% of neurones with NFTs in the hippocampus and 60% in the isocortex colocalize phosphorylated TIF 2α, thus indicating that not all neurones with NFTs over-express phosphorylated TIF 2α. Moreover, phosphorylated TIF 2α immunoreactivity was found in a percentage of neurones expressing phosphorylated SAPK/JNK and p38, which, in turn, are involved in tau phosphorylation in AD. However, dystrophic neurites of senile plaques that contain abnormal tau and express SOD 1 are negative to antiphosphorylated TIF 2α antibodies. Smooth... [ABSTRACT FROM AUTHOR]

Previous studies from our laboratory demonstrated that N ℇ -(carboxymethyl)lysine (CML), one of the major advanced glycation end products (AGE), was accumulated in human pyramidal neurons in the hippocampus in an age-dependent manner. This suggests a potential link between AGE-accumulation and the aging process in neurons. The purpose of the present study was to examine whether this notion could be extended to other AGE structures, such as imidazolone and pentosidine. This was done using 19 human brains that were not affected by dementia. The immunohistochemical survey on distribution in brain tissues of imidazolone and pentosidine was carried out with monoclonal antibodies specific for imidazolone and pentosidine. A parallel control experiment was carried out with anti-CML antibody. The results showed that pentosidine and imidazolone were localized in neurons in different areas of human brain tissue, especially in neurons of CA4 in the hippocampus. The characteristic distribution of pentosidine and imidazolone is very similar to that of CML. Furthermore, when the accumulation of these AGE structures was compared with the age of individual brains it was found that accumulation of imidazolone, pentosidine and CML in the CA4 region increased with age. These findings taken together support the notion that the accumulation of AGE structures in the CA4 region might be closely related to the aging process in neurons. [ABSTRACT FROM AUTHOR]

Summary Tumour necrosis factor-α (TNF-α) is a proinflammatory cytokine produced by several cell types, including T cells upon antigen stimulation. Its production is crucial for the development of an early defence against many pathogens, but its beneficial effects are dependent on the strength and duration of its expression. In this paper we present evidence indicating that serum increases translational efficiency of TNF-α in human peripheral blood mononuclear cells stimulated with superantigen. The increase in translation of TNF-α due to serum could be inhibited by the phosphatidylinositol (PI) 3-K inhibitors, wortmannin and LY294002, suggesting that PI 3-K is involved in the translational control of TNF-α by serum. Similarly to primary T cells, stimulation of Jurkat T cells with superantigen led to TNF-α secretion and this was up-regulated by serum. Transfection of Jurkat cells with a constitutively active form of PI 3-Kα increased the production of TNF-α in cells stimulated with superantigen. Additionally, we used the specific inhibitors targeting ERK kinase and p38 mitogen-activated protein kinase (MAPK), potentially downstream of PI 3-kinase, PD98059 and SB203580. Differently from with PI 3-K inhibitors, the accumulation of TNF-α mRNA was inhibited by PD98059 or SB203580. These results suggest that, in T cells, activation of PI 3-K is an important step in controlling TNF-α protein synthesis in response to growth factors. [ABSTRACT FROM AUTHOR]

NAT1/p97/DAP5 is a newly identified protein that shares homology with the translation initiation factor eIF4G. Studies in vitro and in transfected cells indicated that NAT1 might suppress global translation, thereby repressing cellular proliferation. Here we studied the functions of NAT1 in vivo by disrupting its gene in mice. NAT1−/− embryos died during gastrulation, indicating a crucial role for NAT1 in embryogenesis. Undifferentiated NAT1−/− embryonic stem cells were normal in morphology, proliferation, global translation and gene expression profile. However, NAT1−/− cells exhibited an impaired ability to differentiate: they were resistant to differentiation induced by retinoic acid, and teratomas derived from them consisted of undifferentiated and poorly differentiated tissues. The expression of retinoic acid‐responsive genes, such as the cell‐cycle inhibitor p21WAF1, was selectively impaired in NAT1−/− cells. Transcription from synthetic retinoic acid‐responsive elements was also impaired. These data demonstrated that this translation initiation factor homolog controls specific gene expression pathways required for cellular differentiation. [ABSTRACT FROM AUTHOR]

Gene recruitment is a mechanism of molecular evolution whereby a gene product can function in more than one distinct capacity. The ‘one gene–dual function’ phenomenon is well illustrated by crystallins, structural proteins that play both specialized roles in the eye lens and also ‘housekeeping’ enzyme roles. Ribosomal proteins are integral components of the basal cellular machinery involved in protein synthesis, whose roles have been regarded collectively as important, but individually somewhat mundane. However, various individual ribosomal proteins and also translation initiation and elongation factors have been found to play roles in regulating cell growth, transformation and death, giving rise to increasing speculation that components of the translational apparatus can act as multifunctional proteins. Recently, we have shown that ribosomal protein S3a (RPS3a) plays important roles in cell transformation and death, whereby constitutively or transiently enhanced RPS3a expression can be regarded as ‘priming’ a cell for apoptosis and suppression of such enhanced expression as ‘execution’. While it is unclear whether RPS3a acts in a capacity mechanistically distinct from that in translation, such a possibility is discussed in this article in the light of recent, although not exhaustively reviewed, findings implicating the involvement of other individual ribosomal proteins in modulating and/or effecting changes in cellular responses and growth patterns in an extraribosomal capacity independent of their conventional role in translation. [ABSTRACT FROM AUTHOR]