918 publications from this institution
An increased concentration of end products of lipid peroxidation is the evidence most frequently quoted for the involvement of free radicals in human disease. However, it is likely that increased oxidative damage occurs in most, if not all, human diseases and plays a significant pathological role in only some of them. For example, peroxidation appears to be important in atherosclerosis and in worsening the initial tissue injury caused by ischemic or traumatic brain damage. Oxidative stress can damage many biological molecules; indeed, proteins and DNA are often more significant targets of injury than are lipids, and lipid peroxidation often occurs late in the injury process. Many assays are available to measure lipid peroxidation, but no single assay is an accurate measure of the whole process. Application of simple diene-conjugate and thiobarbituric acid (TBA) assays to human tissues and body fluids can produce artifacts. An HPLC-based TBA test can eliminate some of these artifacts.
Mutations in alpha-synuclein (A30P and A53T) are involved in some cases of familial Parkinson's disease (FPD), but it is not known how they result in nigral cell death. We examined the effect of alpha-synuclein overexpression on the response of cells to various insults. Wild-type alpha-synuclein and alpha-synuclein mutations associated with FPD were overexpressed in NT-2/D1 and SK-N-MC cells. Overexpression of wild-type alpha-synuclein delayed cell death induced by serum withdrawal or H(2)O(2), but did not delay cell death induced by 1-methyl-4-phenylpyridinium ion (MPP(+)). By contrast, wild-type alpha-synuclein transfectants were sensitive to viability loss induced by staurosporine, lactacystin or 4-hydroxy-2-trans-nonenal (HNE). Decreases in glutathione (GSH) levels were attenuated by wild-type alpha-synuclein after serum deprivation, but were aggravated following lactacystin or staurosporine treatment. Mutant alpha-synucleins increased levels of 8-hydroxyguanine, protein carbonyls, lipid peroxidation and 3-nitrotyrosine, and markedly accelerated cell death in response to all the insults examined. The decrease in GSH levels was enhanced in mutant alpha-synuclein transfectants. The loss of viability induced by toxic insults was by apoptosic mechanism. The presence of abnormal alpha-synucleins in substantia nigra in PD may increase neuronal vulnerability to a range of toxic agents.
The brain and nervous system are prone to oxidative stress, and are inadequately equipped with antioxidant defense systems to prevent ‘ongoing’ oxidative damage, let alone the extra oxidative damage imposed by the neurodegenerative diseases. Indeed, increased oxidative damage, mitochondrial dysfunction, accumulation of oxidized aggregated proteins, inflammation, and defects in protein clearance constitute complex intertwined pathologies that conspire to kill neurons. After a long lag period, therapeutic and other interventions based on a knowledge of redox biology are on the horizon for at least some of the neurodegenerative diseases.
glucose-6-phosphatase or putative links between serotonin and the immune system.Both topics are covered and possible future directions discussed.Finally two chapters are devoted to an update on two regulatory enzymes from Escherichia coli, glutamine synthetase and' glutamine-dependent carbamyl phosphate synthetase.
Accumulation of mitochondrial DNA (mtDNA) mutations has been implicated in a wide range of human pathologies, including neurodegenerative diseases, sarcopenia, and the aging process itself. In cells, mtDNA molecules are constantly turned over (i.e. replicated and degraded) and are also exchanged among mitochondria during the fusion and fission of these organelles. While the expansion of a mutant mtDNA population is believed to occur by random segregation of these molecules during turnover, the role of mitochondrial fusion-fission in this context is currently not well understood. In this study, an in silico modeling approach is taken to investigate the effects of mitochondrial fusion and fission dynamics on mutant mtDNA accumulation. Here we report model simulations suggesting that when mitochondrial fusion-fission rate is low, the slow mtDNA mixing can lead to an uneven distribution of mutant mtDNA among mitochondria in between two mitochondrial autophagic events leading to more stochasticity in the outcomes from a single random autophagic event. Consequently, slower mitochondrial fusion-fission results in higher variability in the mtDNA mutation burden among cells in a tissue over time, and mtDNA mutations have a higher propensity to clonally expand due to the increased stochasticity. When these mutations affect cellular energetics, nuclear retrograde signalling can upregulate mtDNA replication, which is expected to slow clonal expansion of these mutant mtDNA. However, our simulations suggest that the protective ability of retrograde signalling depends on the efficiency of fusion-fission process. Our results thus shed light on the interplay between mitochondrial fusion-fission and mtDNA turnover and may explain the mechanism underlying the experimentally observed increase in the accumulation of mtDNA mutations when either mitochondrial fusion or fission is inhibited.
Oxidant species such as superoxide radical (O/sub 2//sup -/), hydrogen peroxide (H/sub 2/O/sub 2/), hydroxyl radical (HO.), and lipid peroxides (LOOH) are becoming increasingly implicated in human disease. However, the question of whether such oxidants are a major cause of tissue injury in human disease or are merely produced during such injury has been difficult to answer because of inadequate experimental techniques, and possibly because of an overemphasis on lipid peroxidation as a mechanism of oxidant injury. Recent developments in methodology, in the authors understanding of the primary mechanism of oxidant toxicity to cells, and in concepts of antioxidant protection are reviewed. Good evidence now exists for some role of oxidant damage to tissues in the pathology of several human diseases, including rheumatoid arthritis, reperfusion injury, immune injury to lung and kidney, and cerebral trauma or ischemia. These have led to promising suggestions for new therapeutic approaches.
Abstract Ergothioneine is a biologically important compound that has been shown to be transported by the organic cation transporter novel type 1 (OCTN1). Following this discovery, a variety of alternate functions for OCTN1 have been suggested including an integral function in the extra-neuronal cholinergic system. The present study reaffirms the primacy of ergothioneine over these alternate substrates using natively expressed OCTN1 in HeLa cells. Besides the general transport inhibitors, quinidine, verapamil and pyrilamine no other putative substrate inhibited ergothioneine transport significantly, with only a slight inhibition demonstrated by carnitine. Even compounds structurally similar to ergothioneine failed to inhibit ergothioneine uptake, suggesting high selectivity of OCTN1. Ergothioneine was found to be avidly accumulated even at low concentrations (300 nM) by HeLa cells.
