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Stefano Govoni

Publications and source records attributed to Stefano Govoni.

At least 19 recordsLinked to original sources
PubMed2006

Nicotinic component of galantamine in the regulation of amyloid precursor protein processing.

Current therapies for Alzheimer's disease treatment rely mainly on acetylcholinesterase inhibitors, improving central cholinergic neurotransmission. Among these molecules, galantamine (GAL) has an interesting pharmacological profile as it is both a reversible acetylcholinesterase inhibitor and an allosteric potentiator of nicotinic cholinergic receptors. We investigated the effect of GAL on the metabolism of the amyloid precursor protein (APP) in differentiated SH-SY5Y neuroblastoma cells. The rationale was based on the suggestion that cholinergic activity may also be involved in the regulation of APP metabolism. We studied the acute effect on APP metabolism measuring the secretion of sAPPalpha in the conditioned medium of cells. Following 2h treatment, GAL 10microM promoted a strong increase in the release of sAPPalpha, the maximal effect approaching on average three-fold baseline value. The compound appeared to increase the release of sAPPalpha, with a mechanism dependent upon an indirect cholinergic stimulation. The effect of GAL was prevented by pre-treatment with alpha-bungarotoxin (40nM) but not low (nanomolar) atropine concentrations, suggesting the specific involvement of nicotinic cholinergic receptors.

Acetylcholinesterase↗
PubMed2006

High interleukin-10 production is associated with low antibody response to influenza vaccination in the elderly.

The present study was designed to determine the correlation among dehydroepiandrosterone (DHEA), cortisol plasma levels, and immune functionality at the time of vaccination with antibody response to influenza vaccination in young and old, healthy volunteers. Fifty-two elderly subjects, ages 63-85 years, and 14 young subjects, ages 26-41 years, entered the study. Plasma levels of DHEA and cortisol and in vitro cytokine production in response to lipopolysaccharide (LPS) and phytohaemagglutinin (PHA) by peripheral blood leukocytes were assessed at the time of vaccination, and antibody titer was measured before and 18 days after influenza virus vaccination. Elderly subjects were characterized by an increase in the cortisol:DHEA ratio, mainly as a result of a decrease in DHEA. A decrease in LPS-induced tumor necrosis factor alpha (TNF-alpha), increased PHA-induced interleukin-10 (IL-10) release, and similar PHA-induced interferon-gamma production were observed in elderly subjects compared with young volunteers. Lower antibody titer to influenza A virus was observed in elderly individuals, and the seroconversion factor was found to be correlated inversely with IL-10 production and correlated directly with TNF-alpha production and to a lesser extent, with the plasma level of DHEA. These results suggest that altered cytokine production in elderly subjects at the moment of vaccination can be predictive of a low response to influenza vaccination and warrant the study of strategies to improve protection afforded by the use of vaccines.

Adult↗
PubMed2006

Sex after stroke: a CNS only dysfunction?

Sexual dysfunction after stroke is a frequent occurrence impacting on the quality of life of the affected patients. Altered sexual activity after stroke is believed to depend upon impairment of brain areas controlling libido and sexual behavior. Co-morbidity and general health status together with psychological factors are important determinants of post stroke sexual functions. More recently, a role for CNS-driven autonomic system dysfunction at the level of male reproductive tract has also been recognized in animal models. This new information may offer novel open interpretations and treatment perspectives of this condition, at least in a portion of the patients.

Animals↗
PubMed2006

Role of acetylcholinesterase inhibitors in pharmacological regulation of amyloid precursor protein processing.

The triggering events leading to the selective neurodegeneration observed in Alzheimer brains are not yet completely understood. They thus create a great challenge for the definition of a resolutive treatment for the causes and symptoms of Alzheimer's Disease (AD). Since the current therapeutic option for AD patients is the use of acetylcholinesterase inhibitors (AChEIs), several authors have examined whether these drugs can also affect the expression and metabolism of the amyloid precursor protein (AbetaPP). The rationale behind these studies was based on the fact that the literature suggests that cholinergic activities are also involved in the regulation of AbetaPP metabolism. Therefore, the characterization of these aspects of AD pharmacology may allow cholinergic drugs to be tested for their ability to intervene at different levels of the pathogenetic chain, other than providing a replacement therapy for lost neurotransmitters. This paper reviews the evidence that many of these drugs, although with different qualitative effects, are able to modulate the metabolism and expression of AbetaPP. This effect is often sustained by an indirect cholinergic mechanism and does not affect the mRNA expression of the precursor, although some other authors have demonstrated an effect on post-transcriptional regulation of AbetaPP expression. In addition to the effect on AbetaPP processing, we recently explored the possibility that these molecules affect a gene expression program beyond the classical pharmacological effects, for insights on possibly unexplored pathways of intervention in AD.

Alzheimer Disease↗
PubMed2006

RACK-1 expression and cytokine production in leukocytes obtained from AD patients.

BACKGROUND AND AIMS: The purpose of this study was to evaluate in vitro cytokine production in blood leukocytes obtained from sporadic AD patients, aged controls and young individuals. METHODS: Diluted whole blood was treated in the presence or absence of LPS (1 microg/mL) for varying times (3-48 h). The release of IL-8, IL-10 and TNF-alpha in conditioned media was evaluated by commercially available sandwich ELISA. RESULTS: Data obtained are indicative of the presence of an unregulated systemic inflammation in AD patients. Leukocytes obtained from AD patients had increased spontaneous TNF-alpha release and decreased LPS-induced IL-10 production, in comparison with both old controls and young subjects, while identical IL-8 production was observed in all groups. The last finding indicates that there was no shift in the potency or efficacy of the response towards LPS with aging, but alterations in downstream signal transduction pathways are probably altered with aging and pathological conditions. CONCLUSIONS: The dysregulation of cytokine production observed in AD patients may partially be explained by a significant reduction in the expression of RACK-1, a protein crucial for integration of signaling pathways with different physiological functions, such as cytokine production.

Adult↗
PubMed2005

Role of acetylcholinesterase inhibitors in the regulation of amyloid beta precursor protein (AbetaPP) metabolism.

The events that lead to neurodegeneration in Alzheimer's brains are largely unknown and this fact creates a great challenge for the definition of treatments that may be resolutive for Alzheimer's disease (AD). The current therapeutic option for AD patients is the use of acetylcholinesterase inhibitors (AChEIs), which gives a symptomatic relief to some of the clinical manifestations of the disease. In addition, several authors investigated whether these drugs can also affect one of the major pathogenetic pathway postulated for the disease, that is the expression and metabolism of the amyloid precursor protein (AbetaPP). The literature suggests that cholinergic activities may be significantly involved in the regulation of AbetaPP metabolism, thus the characterisation of these aspects of AD pharmacology may allow testing cholinergic drugs in their ability to intervene at different levels of the pathogenetic chain, other than to provide a replacement therapy for lost neurotransmitters. In this paper we review the evidence that these drugs, albeit with different quantitative and qualitative effects, can modulate the metabolism and expression of AbetaPP, through mechanism that involve either an indirect cholinergic mechanism or effects that do not involve the canonical pharmacological activity of AChE inhibitors. We also provide preliminary evidence that these molecules may affect a gene expression program beyond the classical pharmacological pattern suggesting an insight on possible unexplored pathways of intervention in AD.

Acetylcholinesterase↗
PubMed2005

Identification of a mutant-like conformation of p53 in fibroblasts from sporadic Alzheimer's disease patients.

Here we show that fibroblasts from sporadic Alzheimer's disease (AD) patients specifically express an anomalous and detectable conformational state of p53 that makes these cells distinct from fibroblasts of age-matched non-AD subjects. In particular, we found that, in contrast to non-AD fibroblasts, p53 in AD fibroblasts is expressed at higher levels in resting condition, and presents a significant impairment of its DNA binding and transcriptional activity. All together, these findings figured out the presence of a mutant-like p53 phenotype. However, gene sequencing of the entire p53 gene from either AD or non-AD did not unravel point mutations. Based on immunoprecipitation studies with conformation-specific p53 antibodies (PAb1620 and PAb240), which discriminated folded versus unfolded p53 tertiary structure, we found that a significant amount of p53 assumed an unfolded tertiary structure in fibroblasts from AD patients. This conformational mutant-like p53 form was virtually undetectable in fibroblasts from non-AD patients. These data, independently from their relevance in understanding the etiopathogenesis of AD, might be useful for supporting AD diagnosis.

Aged↗
PubMed2005

Neuronal ELAV proteins enhance mRNA stability by a PKCalpha-dependent pathway.

More than 1 in 20 human genes bear in the mRNA 3' UTR a specific motif called the adenine- and uridine-rich element (ARE), which posttranscriptionally determines its expression in response to cell environmental signals. ELAV (embryonic lethal abnormal vision) proteins are the only known ARE-binding factors that are able to stabilize the bound mRNAs, thereby positively controlling gene expression. Here, we show that in human neuroblastoma SH-SY5Y cells, neuron-specific ELAV (nELAV) proteins (HuB, HuC, and HuD) are up-regulated and redistributed by 15 min of treatment with the activators of PKC phorbol esters and bryostatin-1. PKC stimulation also induces nELAV proteins to colocalize with the translocated PKCalpha isozyme preferentially on the cytoskeleton, with a concomitant increase of nELAV threonine phosphorylation. The same treatment promotes stabilization of growth-associated protein 43 (GAP-43) mRNA, a well known nELAV target, and induces an early increase in GAP-43 protein concentration, again only in the cytoskeletal cell fraction. Genetic or pharmacological inactivation of PKCalpha abolishes nELAV protein cytoskeletal up-regulation, GAP-43 mRNA stabilization, and GAP-43 protein increase, demonstrating the primary role of this specific PKC isozyme in the cascade of nELAV recruitment. Finally, in vivo PKC activation is associated with an up-regulation of nELAV proteins in the hippocampal rat brain. These findings suggest a model for gene expression regulation by nELAV proteins through a PKCalpha-dependent pathway that is relevant for the cellular programs in which ARE-mediated control plays a pivotal role.

3' Untranslated Regions↗
PubMed2004

Age-related decline in RACK-1 expression in human leukocytes is correlated to plasma levels of dehydroepiandrosterone.

Aging is associated with remodeling of the immune system, contributing to increased incidence of infections, autoimmune diseases, and cancer among the elderly. Alterations in several signal transduction pathways have been reported to play an important role in immunosenescence. We show that peripheral blood leukocytes obtained from old donors (> or =65 years) have a significantly reduced expression of receptor for activated C kinase 1 (RACK-1), a protein required for protein kinase C (PKC)-beta signaling, as compared with young donors (< or =40 years), both in males and females. The decline in RACK-1 immunoboth in reactivity was age-related (Spearman correlation, r=-0.278, P=0.012). All leukocyte subpopulations, namely lympho-monocytes, granulocytes, and B and T cells, showed a similar defect. We also observed a direct correlation between circulating dehydroepiandrosterone (DHEA) and RACK-1 expression in leukocytes (Spearman correlation, r=0.388, P=0.001). Furthermore, in vitro treatment with DHEA resulted in increased RACK-1 expression in leukocytes and lymphocyte proliferation, confirming the role of this hormone in the modulation of its expression and immune functions. A relevant consequence of RACK-1-reduced expression was the observation that release of tumor necrosis factor alpha following lipopolysaccharide challenge and mitogen-induced lymphocye proliferation, which involves PKC-beta activation, was significantly reduced in elderly subjects. Overall, our findings contribute to the understanding of the complex process of immunosenescence and identify age-related loss in immunological responses as partially associated with decreased RACK-1 expression.

Adult↗
PubMed2004

In vitro and ex vivo antihydroxyl radical activity of green and roasted coffee.

The specific antiradical activity against the hydroxyl radical of the water soluble components in green and dark roasted Coffea arabica and Coffea robusta coffee samples, both in vitro by the chemical deoxiribose assay and ex vivo in a biological cellular system (IMR32 cells), were determined. All the tested coffee solutions showed remarkable antiradical activity. In the deoxiribose assay, all the tested solutions showed similar inhibitory activity (IA%) against the sugar degradation (IA values ranged from 45.2 to 46.9%). In the cell cultures, the survival increase (SI%) ranged from 197.0 to 394.0% with C. robusta roasted coffee being significantly more active than the other samples. The coffee solutions underwent dialysis (3500 Da cutoff membrane) to fraction their components. In both systems, the dialysates (MW < 3500 Da) either from green or roasted coffee, showed antiradical activity, while the only retentates (MW > 3500 Da) from the roasted coffee samples were active. The preparative gel-filtration chromatography of roasted coffee C. robusta dialysate gave three fractions active in the biological system, all containing chlorogenic acid derivatives. The most active fraction was found to be that containing the 5-O-caffeoilquinic acid, which shows a linear relation dose-response ranging from 0.02 to 0.10 mM. The results show that both green and roasted coffee possess antiradical activity, that their more active component is 5-O-caffeoyl-quinic acid, and moreover that roasting process induces high MW components (later Maillard reaction products, i.e., melanoidins), also possessing antiradical activity in coffee. These results could explain the neuroprotective effects found for coffee consumption in recent epidemiological studies.

Antioxidants↗
PubMed2004

Increase of the RNA-binding protein HuD and posttranscriptional up-regulation of the GAP-43 gene during spatial memory.

Neuronal ELAV-like proteins (HuB, HuC, and HuD) are highly conserved RNA-binding proteins able to selectively associate with the 3' UTR of a subset of target mRNAs and increase their cytoplasmic stability and rate of translation. We previously demonstrated the involvement of these proteins in learning, reporting that they undergo a sustained up-regulation in the hippocampus of mice trained in a spatial discrimination task. Here, we extend this finding, showing that a similar up-regulation occurs in the hippocampus of rats trained in another spatial learning paradigm, the Morris water maze. HuD, a strictly neuron-specific ELAV-like protein, is shown to increase after learning, with a preferential binding to the cytoskeletal fraction. HuD up-regulation is associated with an enhancement of GAP-43 mRNA and protein levels, with an apparently increased HuD colocalization with the GAP-43 mRNA and an increased association of neuronal ELAV-like proteins with the GAP-43 mRNA. These learning-dependent biochemical events appear to be spatiotemporally controlled, because they do not occur in another brain region involved in learning, the retrosplenial cortex, and at the level of protein expression they show extinction 1 month after training despite memory retention. By contrast, HuD mRNA levels still remain increased after 1 month in the CA1 region. This persistence may have implications for long-term memory recall.

Animals↗
PubMed2004

Capillary electrophoresis studies on the aggregation process of beta-amyloid 1-42 and 1-40 peptides.

The possibility to monitor, in solution, the steps of beta-amyloid (Abeta) nucleation and therefore to describe this dynamic process by using capillary electrophoresis and under optimized experimental conditions is described. Striking differences in the electrophoretic patterns of Abeta 1-42 and Abeta 1-40 over time are here shown, and different aggregation states are elucidated, which reflect the very diverse oligomerization behavior of two very similar peptides. The isolation of one aggregated species of high molecular weight by ultracentrifugation allowed us to assess its role as toxic oligomer. The perturbation of the existing equilibrium among the identified species by the addition of small molecules can in principle interfere with the aggregation process of the peptides and ultimately prevent the plaque formation in vitro.

Amyloid beta-Peptides↗
PubMed2004

Expression and phosphorylation of delta-CaM kinase II in cultured Alzheimer fibroblasts.

Dysregulation of calcium homeostasis is among the major cellular alterations in Alzheimer's disease (AD). We studied Ca(2+)/calmodulin-dependent protein kinase II (CaM kinase II), one of the major effectors regulating neuronal responses to changes in calcium fluxes, in cultured skin fibroblasts from subjects with sporadic AD. We found, by using PCR and Western analysis, that human fibroblasts express the delta-isoform of this kinase, and that CaM kinase II is the major Ca(2+)/calmodulin-dependent kinase in these cells. Protein expression level of the kinase was not significantly different in AD fibroblasts. However, the total activity of the kinase (stimulated by Ca(2+)/calmodulin) was significantly reduced in AD cell lines, whereas Ca(2+)-independent activity was significantly enhanced. The percent autonomy of the kinase (%Ca(2+)-independent/Ca(2+)-dependent activity) in AD cell lines was 62.8%, three-fold the corresponding percentage in control fibroblasts. The abnormal calcium-independent activity was not due to enhanced basal autophosphorylation of Thr(287). The observed abnormalities, if present in brain tissue, may be implicated either in dysfunction of neuroplasticity and cognitive functions or in dysregulation of cell cycle.

Aged↗
PubMed2004

Acetylcholinesterase inhibitors: novel activities of old molecules.

The therapeutic approach for improving the cognitive function in patients with Alzheimer's disease (AD) is mainly based on the potentiation of central cholinergic activity and is achieved clinically by the use of acetylcholinesterase (AChE) inhibitors such as tacrine, donepezil, rivastigmine, galantamine and other drugs currently in clinical trials. These are, by their pharmacology, only symptomatic drugs yet recently these molecules have shown some potential also in the modulation of amyloid precursor protein (APP) processing. We explore in this review the experimental evidence that suggests a role for AChEIs in APP processing and point to multiple complex mechanisms involving either a cholinergic agonist effect, coupled to multiple signal transduction pathways, or post-transcriptional effects that modulate the expression of cellular APP.

Alzheimer Disease↗
PubMed2004

Emerging targets for the pharmacology of learning and memory.

Learning and memory are dynamic processes associated with modifications in morphology, biochemistry and physiology of the nervous system, that can be analysed at different levels of biological organization. Within this context, changes correlated with cognitive processes are identifiable at distinct cellular and molecular loci of the nervous system. Synaptic plasticity represents an experience-dependent alteration of neuronal properties that subserve learning and memory, and for which a neuronal network can be considered as a candidate for being part of an engram. Multiple molecular systems at various levels of the signal transduction cascade, such as those involving receptors, second messengers and gene expression, may be linked to synaptic remodelling during cognitive processes. After a brief overview of the various facets of memory and the higher levels of cerebral organization (with special attention to the hippocampus), this review is devoted to the presentation of some novel potential therapeutic targets within the signal transduction cascade that might be considered for rational pharmacological intervention to improve learning and memory in both diseased and healthy individuals.

Animals↗
PubMed2004

Differential involvement of protein kinase C alpha and epsilon in the regulated secretion of soluble amyloid precursor protein.

We investigated the differential role of protein kinase C (PKC) isoforms in the regulated proteolytic release of soluble amyloid precursor protein (sAPPalpha) in SH-SY5Y neuroblastoma cells. We used cells stably transfected with cDNAs encoding either PKCalpha or PKCepsilon in the antisense orientation, producing a reduction of the expression of PKCalpha and PKCepsilon, respectively. Reduced expression of PKCalpha and/or PKCepsilon did not modify the response of the kinase to phorbol ester stimulation, demonstrating translocation of the respective isoforms from the cytosolic fraction to specific intracellular compartments with an interesting differential localization of PKCalpha to the plasma membrane and PKCepsilon to Golgi-like structures. Reduced expression of PKCalpha significantly impaired the secretion of sAPPalpha induced by treatment with phorbol esters. Treatment of PKCalpha-deficient cells with carbachol induced a significant release of sAPPalpha. These results suggest that the involvement of PKCalpha in carbachol-induced sAPPalpha release is negligible. The response to carbachol is instead completely blocked in PKCepsilon-deficient cells suggesting the importance of PKCepsilon in coupling cholinergic receptors with APP metabolism.

Amyloid beta-Protein Precursor↗
PubMed2004

Familial migraine with aura: association study with 5-HT1B/1D, 5-HT2C, and hSERT polymorphisms.

BACKGROUND: The serotonergic system has a significant role in the pathophysiology and pharmacology of migraine. OBJECTIVE: To study the association between the occurrence of migraine with aura and 5-HT(1B/1D) and 5-HT(2C) receptor gene and the human serotonin transporter (hSERT) gene polymorphisms in 18 unrelated families with multiple affected members. METHOD: Two polymorphisms in the 5-HT(1B/1D) receptor gene and one polymorphism in the 5-HT(2C) receptor gene were studied by restriction fragment length polymorphism analysis. Allelic variation of the hSERT, with 9, 10, and 12 copies of a "repetitive element," was studied by polymerase chain reaction amplification of the variable number tandem repeat region. RESULTS: Allelic distribution of 5-HT(1B/1D) and 5-HT(2C) receptor gene polymorphisms in affected patients did not differ in either of the control groups (unaffected relatives or unrelated healthy individuals). A trend toward a significant effect of the 12-repeat hSERT allele as a risk factor for migraine with aura versus unrelated controls was observed. CONCLUSION: Our data do not support the involvement of 5-HT(1B/1D) and 5-HT(2C) receptor gene polymorphisms in migraine with aura, yet do suggest a possible role for a locus at or near the hSERT gene in the susceptibility to migraine with aura.

Adult↗