Ken Rodgers trained as a pharmacist in the United Kingdom and had ten years experience in the pharmaceutical industry before embarking on an academic research career. After completing his Ph.D. studies in the Faculty of Medicine at the University of Sydney he was awarded a Pfizer postdoctoral fellowship and spent two years in the United Kingdom working with Dr Chris Jackson in the plaque rupture group at the Bristol Heart Institute and with Pfizer drug development in Kent.
In 1999 Ken returned to Australia to take up a Senior Research Officer position at the Heart Research Institute in Sydney with Professor Roger Dean. This resulted some seminal work on the cellular handling of oxidised proteins, made possible by the development of a novel experimental approach to generate oxidised proteins in cells. Ken was the head of the Cell Biology Research Group at the Heart Research Institute in Sydney from 2005 to 2011 where he published on the protein oxidation, incorporation of non-native amino acids into proteins, atherosclerosis and plaque rupture.
In February 2011 he joined the University of Technology Sydney as a senior lecturer in pharmacology. His research laboratory is now located in the School of Medical and Molecular Biosciences at UTS, which is a well-equipped research collective. He also holds a visiting scientist position at the Heart Research Institute. His main research interests are on how incorporation of non-protein amino acids into proteins could be an environmental trigger for neurodegeneration.
Registered pharmacist: Pharmacy Board of Australia
Founding Member of the Royal Pharmaceutical Society of Great Britain
Cyanobacterial and algal toxins
Environmental risk factors for neurodegenerative diseases
Atherosclerosis and plaque rupture
Samardzic, K & Rodgers, KJ 2019, 'Cell death and mitochondrial dysfunction induced by the dietary non-proteinogenic amino acid l-azetidine-2-carboxylic acid (Aze)', AMINO ACIDS, vol. 51, no. 8, pp. 1221-1232.View/Download from: Publisher's site
Samardzic, K & Rodgers, KJ 2019, 'Cytotoxicity and mitochondrial dysfunction caused by the dietary supplement l-norvaline.', Toxicology in vitro : an international journal published in association with BIBRA, vol. 56, pp. 163-171.View/Download from: Publisher's site
In addition to the 20 protein amino acids that are encoded for protein synthesis, hundreds of other naturally occurring amino acids, known as non-proteinogenic amino acids (NPAAs) exist. It is well known that some NPAAs are toxic through their ability to mimic protein amino acids, either in protein synthesis or in other metabolic pathways, and this property is utilised by some plants to inhibit the growth of other plants or kill herbivores. L-norvaline is an NPAA readily available for purchase as a dietary supplement. In light of previous evidence of l-norvaline's antifungal, antimicrobial and herbicidal activity, we examined the toxicity of l-norvaline to mammalian cells in vitro and showed that l-norvaline decreased cell viability at concentrations as low as 125 μM, caused necrotic cell death and significant changes to mitochondrial morphology and function. Furthermore, toxicity was reduced in the presence of structurally similar 'protein' amino acids, suggesting l-norvaline's cytotoxicity could be attributed to protein amino acid mimicry.
Giannopoulos, S, Samardzic, K, Raymond, BBA, Djordjevic, SP & Rodgers, KJ 2019, 'L-DOPA causes mitochondrial dysfunction in vitro: a novel mechanism of L-DOPA toxicity uncovered.', The international journal of biochemistry & cell biology, vol. 117.View/Download from: Publisher's site
In Parkinson's disease (PD), as in many other neurodegenerative disorders, mitochondrial dysfunction, protein misfolding, and proteotoxic stress underly the disease process. For decades, the primary symptomatic treatment for PD has been the dopamine precursor L-DOPA (Levodopa). L-DOPA however can initiate protein misfolding through its ability to mimic the protein amino acid L-tyrosine, resulting in random errors in aminoacylation and L-DOPA becoming mistakenly inserted into the polypeptide chain of proteins in place of L-tyrosine. In the present study we examined the impact that the generation of DOPA-containing proteins had on human neuroblastoma cell (SH-SY5Y) function in vitro. We showed that even in the presence of antioxidants there was a significant accumulation of cytosolic ubiquitin in DOPA-treated cells, an upregulation in the endosomal-lysosomal degradation system, deleterious changes to mitochondrial morphology and a marked decline in mitochondrial function.The effects of L-DOPA on mitochondrial function were not observed with D-DOPA, the stereoisomer of L-DOPA that cannot be inserted into proteins so did not result from oxidative stress. We could fully protect against these effects by co-treatment with L-tyrosine, supporting the view that misincorporation of L-DOPA into proteins contributed to these cytotoxic effects, leading us to suggest that co-treatment with L-tyrosine could be beneficial therapeutically.
Violi, JP, Facey, JA, Mitrovic, SM, Colville, A & Rodgers, KJ 2019, 'Production of β-methylamino-L-alanine (BMAA) and Its Isomers by Freshwater Diatoms.', Toxins, vol. 11, no. 9.View/Download from: Publisher's site
β-methylamino-L-alanine (BMAA) is a non-protein amino acid that has been implicated as a risk factor for motor neurone disease (MND). BMAA is produced by a wide range of cyanobacteria globally and by a small number of marine diatoms. BMAA is commonly found with two of its constitutional isomers: 2,4-diaminobutyric acid (2,4-DAB), and N-(2-aminoethyl)glycine (AEG). The isomer 2,4-DAB, like BMAA, has neurotoxic properties. While many studies have shown BMAA production by cyanobacteria, few studies have looked at other algal groups. Several studies have shown BMAA production by marine diatoms; however, there are no studies examining freshwater diatoms. This study aimed to determine if some freshwater diatoms produced BMAA, and which diatom taxa are capable of BMAA, 2,4-DAB and AEG production. Five axenic diatom cultures were established from river and lake sites across eastern Australia. Cultures were harvested during the stationary growth phase and intracellular amino acids were extracted. Using liquid chromatography triple quadrupole mass spectrometry (LC-MS/MS), diatom extracts were analysed for the presence of both free and protein-associated BMAA, 2,4-DAB and AEG. Of the five diatom cultures analysed, four were found to have detectable BMAA and AEG, while 2,4-DAB was found in all cultures. These results show that BMAA production by diatoms is not confined to marine genera and that the prevalence of these non-protein amino acids in Australian freshwater environments cannot be solely attributed to cyanobacteria.
Violi, JP, Mitrovic, SM, Colville, A, Main, BJ & Rodgers, KJ 2019, 'Prevalence of β-methylamino-L-alanine (BMAA) and its isomers in freshwater cyanobacteria isolated from eastern Australia.', Ecotoxicology and environmental safety, vol. 172, pp. 72-81.View/Download from: Publisher's site
Environmental exposure to the amino acid β-methylamino-L-alanine (BMAA) was linked to the high incidence of neurodegenerative disease first reported on the island of Guam in the 1940s and has more recently been implicated in an increased incidence of amyotrophic lateral sclerosis (ALS) in parts of the USA. BMAA has been shown to be produced by a range of cyanobacteria and some marine diatoms and dinoflagellates in different parts of the world. BMAA is commonly found with two of its constitutional isomers: 2,4- diaminobutyric acid (2,4-DAB) and N-(2-aminoethyl) glycine (AEG). These isomers are thought to be co-produced by the same organisms that produce BMAA and MS/MS analysis following LC separation can add an additional level of specificity over LC-FL. Although the presence of BMAA and 2,4-DAB in surface scum samples from several sites in Australia has been reported, which Australian cyanobacterial species are capable of BMAA, 2,4-DAB and AEG production remains unknown. The aims of the present studies were to identify some of the cyanobacterial genera or species that can produce BMAA, 2,4-DAB and AEG in freshwater cyanobacteria blooms in eastern Australia. Eleven freshwater sites were sampled and from these, 19 single-species cyanobacterial cultures were established. Amino acids were extracted from cyanobacterial cultures and analysed using liquid chromatography-tandem mass spectrometry. BMAA was detected in 17 of the 19 isolates, 2,4-DAB was detected in all isolates, and AEG was detected in 18 of the 19 isolates, showing the prevalence of these amino acids in Australian freshwater cyanobacteria. Concentrations of all three isomers in Australian cyanobacteria were generally higher than the concentrations reported elsewhere. This study confirmed the presence of BMAA and its isomers in cyanobacteria isolated from eastern Australian freshwater systems, and determined which Australian cyanobacterial genera or species were capable of producing them when cultured unde...
Main, BJ & Rodgers, KJ 2018, 'Assessing the Combined Toxicity of BMAA and Its Isomers 2,4-DAB and AEG In Vitro Using Human Neuroblastoma Cells.', Neurotoxicity Research, vol. Volume 33, no. 1, pp. 33-42.View/Download from: Publisher's site
The non-protein amino acid (NPAA) ß-methylamino-L-alanine (BMAA) is produced by a diverse range of cyanobacteria, diatoms and dinoflagellates, and is present in both aquatic and terrestrial ecosystems globally. Exposure to BMAA has been implicated in the development of neurodegenerative diseases including amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD) and Parkinson's disease (PD). BMAA is often found in nature along with its structural isomers 2,4-diaminobutyric acid (2,4-DAB) and aminoethylglycine (AEG); however, the toxicity of these NPAAs in combination has not been examined. We have previously demonstrated that BMAA induces endoplasmic reticulum (ER) stress and increases caspase and cathepsin activity in human neuroblastoma cells (SH-SY5Y), effects consistent with proteotoxic stress due to disturbances in protein synthesis, folding or turnover. The current study investigates whether 2,4-DAB and AEG share a similar mechanism of toxicity to BMAA, and if simultaneous exposure of cells to BMAA and its isomers results in increased toxicity in vitro. We show that a 48-h treatment with both 500 μM BMAA and 2,4-DAB decreases cell viability in vitro whereas AEG was not cytotoxic under the same conditions. Treatment of SH-SY5Y cells with 2,4-DAB did not increase expression of ER stress markers. Combined treatment of cells with BMAA and 2,4-DAB resulted in increased caspase activity and increased apoptosis above that of BMAA or 2,4-DAB on their own. These results suggest that 2,4-DAB does not share the same mechanism of toxicity as BMAA but the presence of 2,4-DAB increases the toxicity of BMAA to human cells in vitro.
Main, BJ, Italiano, CJ & Rodgers, KJ 2018, 'Investigation of the interaction of β-methylamino-L-alanine with eukaryotic and prokaryotic proteins.', Amino Acids, vol. 50, no. 3-4, pp. 397-407.View/Download from: Publisher's site
There is a strong body of evidence linking the non-protein amino acid (NPAA) β-methylamino-L-alanine (BMAA) to the development of a number of neurodegenerative diseases. BMAA has been found globally, is produced by a number of organisms including cyanobacteria, diatoms, and dinoflagellates; and has been shown to biomagnify through trophic levels. The role of BMAA in neurodegenerative disease is highlighted by its presence in the brains of a number of neurodegenerative disease patients, where it was found in a protein-bound form. We have previously shown that BMAA is bound to cell proteins, and results in the upregulation of the unfolded protein response, an endoplasmic reticulum stress response activated by the presence of misfolded proteins within the cell. Structurally aberrant proteins are features of a number of neurodegenerative diseases, and further investigation of how BMAA interacts with proteins is crucial to our understanding of its toxicity. Here we use radiolabelled BMAA to investigate the interaction and binding of BMAA to eukaryotic and prokaryotic proteins. We found differences in the presence and distribution of protein-bound BMAA between E. coli and neuroblastoma cells, with an increase in binding over time only seen in the eukaryotic cells. We also found that BMAA was unable to bind to pure proteins, or cell lysate in native or denaturing conditions, indicating that biological processing is required for BMAA to bind to proteins.
Rodgers, KJ, Main, BJ & Samardzic, K 2018, 'Cyanobacterial Neurotoxins: Their Occurrence and Mechanisms of Toxicity.', Neurotoxicity research, vol. 33, no. 1, pp. 168-177.View/Download from: Publisher's site
Cyanobacteria are some of the oldest organisms on earth, and have evolved to produce a battery of toxic metabolites, including hepatotoxins, dermatoxins, and neurotoxins. In this review, we focus on the occurrence and mechanisms of toxicity of a number of neurotoxins synthesised by these ancient photosynthetic prokaryotes. We discuss the evidence linking β-methylamino-L-alanine (BMAA), a non-protein amino acid, to an unusual neurological disease complex reported on the island of Guam in the 1950s, and how 60 years later, the role that BMAA plays in human disease is still unclear. There is now evidence that BMAA is also produced by some eukaryotes, and can bioaccumulate in food chains; this combined with higher frequency of cyanobacterial blooms globally, increases the potential for human exposure. Three BMAA isomers that often co-occur with BMAA have been identified, and the current knowledge on the toxicity of these molecules is presented. The acute alkaloid toxins; anatoxin-a, homoanatoxin-a and the saxitoxins, and the organophosphate neurotoxin anatoxin-a(S) are also discussed. In many cases, human exposure to a cocktail of cyanobacterial neurotoxins is likely; however, the implications of combined exposure to these toxins have not been fully explored. Increased understanding of the combined effects of cyanobacterial neurotoxins is required to fully understand how these molecules impact on human health.
Main, BJ, Bowling, LC, Padula, MP, Bishop, DP, Mitrovic, SM, Guillemin, GJ & Rodgers, KJ 2018, 'Detection of the suspected neurotoxin β-methylamino-l-alanine (BMAA) in cyanobacterial blooms from multiple water bodies in Eastern Australia.', Harmful algae, vol. 74, pp. 10-18.View/Download from: Publisher's site
The emerging toxin β-methylamino-l-alanine (BMAA) has been linked to the development of a number of neurodegenerative diseases in humans including amyotrophic lateral sclerosis (ALS), Alzheimer's disease, and Parkinson's disease. BMAA has been found to be produced by a range of cyanobacteria, diatoms, and dinoflagellates worldwide, and is present in freshwater, saltwater, and terrestrial ecosystems. Surface scum samples were collected from waterways in rural and urban New South Wales, Australia and algal species identified. Reverse phase liquid chromatography-tandem mass spectrometry was used to analyse sixteen cyanobacterial scum for the presence of BMAA as well as its toxic structural isomer 2,4-diaminobutyric acid (2,4-DAB). BMAA was detected in ten of the samples analysed, and 2,4-DAB in all sixteen. The presence of these toxins in water used for agriculture raises concerns for public health and food security in Australia.
The 'oxygen paradox' arises from the fact that oxygen, the molecule that aerobic life depends on, threatens its very existence. An oxygen-rich environment provided life on Earth with more efficient bioenergetics and, with it, the challenge of having to deal with a host of oxygen-derived reactive species capable of damaging proteins and other crucial cellular components. In this minireview, we explore recent insights into the metabolism of proteins that have been reversibly or irreversibly damaged by oxygen-derived species. We discuss recent data on the important roles played by the proteasomal and lysosomal systems in the proteolytic degradation of oxidatively damaged proteins and the effects of oxidative damage on the function of the proteolytic pathways themselves. Mitochondria are central to oxygen utilisation in the cell, and their ability to handle oxygen-derived radicals is an important and still emerging area of research. Current knowledge of the proteolytic machinery in the mitochondria, including the ATP-dependent AAA+ proteases and mitochondrial-derived vesicles, is also highlighted in the review. Significant progress is still being made in regard to understanding the mechanisms underlying the detection and degradation of oxidised proteins and how proteolytic pathways interact with each other. Finally, we highlight a few unanswered questions such as the possibility of oxidised amino acids released from oxidised proteins by proteolysis being re-utilised in protein synthesis thus establishing a vicious cycle of oxidation in cells.
Main, BJ, Dunlop, RA & Rodgers, KJ 2016, 'The use of L-serine to prevent beta-methylamino-L-alanine (BMAA)-induced proteotoxic stress in vitro', TOXICON, vol. 109, pp. 7-12.View/Download from: Publisher's site
Reyna Zeballos, JL, Meier, P, Geronimo, F & Rodgers, K 2016, 'Implementing Digital Media Presentations as Assessment Tools for Pharmacology Students', American Journal of Educational Research, vol. 4, no. 14, pp. 983-991.View/Download from: Publisher's site
At the Faculty of Science we introduced the use of digital presentations as assessment tools for
third-year pharmacology students. A cohort of 167 students self-allocated into groups of four and were assigned a
topic related to the pharmacology lecture material. A one-hour lecture was delivered to discuss digital media
principles (visual design, video composition, multimedia learning principles, etc.) and how to apply these to create
digital media projects. During practical classes, students developed a storyboard and received feedback and technical
advice from tutors. Towards the end of the semester, students uploaded their preliminary presentations to a YouTube
channel and received feedback from lecturers, tutors, and peers before submitting the final version. A marking rubric
was developed and shared with students at the beginning of the semester. The study used a mixed-methods approach
to evaluating the intervention. A comprehensive 35-step questionnaire was used, covering demographics, students'
attitudes towards technology, digital media support, understanding of the assignment, and knowledge construction
and skills gained. It also contained five open-ended questions. A high response rate was achieved for the voluntary
survey (97/167). Additionally, students reviewed contributions of group members using SPARKPlus, and the marks
attained were used to triangulate the questionnaire responses. In summary, the data shows that students found the
assignment was engaging, fostered learning and creativity, and that they gained additional skills relevant to their
Geronimo, FRB, Barter, PJ, Rye, KA, Heather, AK, Shearston, KD & Rodgers, KJ 2016, 'Plaque stabilizing effects of apolipoprotein A-IV', ATHEROSCLEROSIS, vol. 251, pp. 39-46.View/Download from: Publisher's site
Dunlop, RA, Main, BJ & Rodgers, K 2015, 'The deleterious effects of non-protein amino acids from desert plants on human and animal health', Journal of Arid Environments, vol. 112B, pp. 152-158.View/Download from: Publisher's site
Since plants lack the ability to remove themselves from sites of predation, they have evolved alternative defences to keep predators at bay. Mechanical defences include camouflage, the addition of thorns and spikes as well as growing in locations not easily accessed by herbivores. Chemical defences include the synthesis of compounds that are toxic to predatory species and can also inhibit or retard the growth of other plant species in a process termed allelopathy. Amongst these chemicals is a reservoir of non-protein amino acids that mediate toxicity. These non-protein amino acids can be charged by tRNA synthetases and subsequently mis-incorporated into nascent polypeptides, resulting in aberrant, dysfunctional proteins that can be toxic to predators. Some species such as the bruchid beetle Bruchus rufimanus (Chrysomelidae), which feeds on the jack bean Canavalia ensiformis (Fabaceae) plant, have evolved advanced tRNA synthetases that are able to discriminate between protein and non-protein amino acids, thus remain unaffected. Other species including livestock and humans that do not possess such selectivity are susceptible to plant toxins. In this brief review we discuss the mechanisms of action and consequences of exposure to plant-derived non-protein amino acids with a focus on those derived from plants from arid environments.
Shiozawa-West, N, Dunlop, RA & Rodgers, KJ 2015, 'Using an in vitro model to study oxidised protein accumulation in ageing fibroblasts.', Biochimica et biophysica acta, vol. 1850, no. 11, pp. 2177-2184.View/Download from: Publisher's site
BACKGROUND: The accumulation of oxidised proteins in ageing cells and tissues results from an increase in oxidant damage coupled with impaired degradation of the damaged proteins. Heat Shock Proteins (HSP) and other chaperones are required to recognise damaged proteins and transport them to the lysosomal and proteasomal degradation pathways. How these systems fail in ageing cells is not clear. METHODS: We monitor oxidised protein accumulation, the activity of the proteasome and lysosomal proteases, and HSP levels in MRC-5 fibroblasts throughout their mitotic lifespan. We then use a novel in vitro cell culture model to experimentally generate oxidised proteins in young and old MRC-5 fibroblasts and compare their rates of degradation and changes in the key pathways involved in oxidised protein removal. RESULTS: We show that the activity of the proteasome and some lysosomal enzymes decreases with ageing in MRC-5 cells as do levels of HSP70 but this is not associated with an accumulation of oxidised proteins which only occurs as cells closely approach post-mitotic senescence. Old cells are unable to degrade experimentally generated oxidised proteins as efficiently as young cells. Exposure to mild heat stress however increases the efficiency of oxidised protein degradation by young cells and increases levels of HSP70. CONCLUSIONS: Our results highlight the importance of the HSP/chaperone system in oxidised protein metabolism, particularly in aging cells. GENERAL SIGNIFICANCE: These data might have implications for the development of therapies for pathologies associated with protein accumulation and suggest that the HSP/chaperone system would be an important target.
Animals, in common with plants and microorganisms, synthesise proteins from a pool of 20 protein amino acids (plus selenocysteine and pyrolysine) (Hendrickson et al., 2004). This represents a small proportion (~2%) of the total number of amino acids known to exist in nature (Bell, 2003). Many 'non-protein' amino acids are synthesised by plants, and in some cases constitute part of their chemical armoury against pathogens, predators or other species competing for the same resources (Fowden et al., 1967). Microorganisms can also use selectively toxic amino acids to gain advantage over competing organisms (Nunn et al., 2010). Since non-protein amino acids (and imino acids) are present in legumes, fruits, seeds and nuts, they are ubiquitous in the diets of human populations around the world. Toxicity to humans is unlikely to have been the selective force for their evolution, but they have the clear potential to adversely affect human health. In this review we explore the links between exposure to non-protein amino acids and neurodegenerative disorders in humans. Environmental factors play a major role in these complex disorders which are predominantly sporadic (Coppede et al., 2006). The discovery of new genes associated with neurodegenerative diseases, many of which code for aggregation-prone proteins, continues at a spectacular pace but little progress is being made in identifying the environmental factors that impact on these disorders. We make the case that insidious entry of non-protein amino acids into the human food chain and their incorporation into protein might be contributing significantly to neurodegenerative damage.
Dunlop, RA, Cox, P, Banack, S & Rodgers, K 2013, 'The Non-Protein Amino Acid BMAA Is Misincorporated into Human Proteins in Place of L-Serine Causing Protein Misfolding and Aggregation', Plos One, vol. 8, no. 9, pp. 1-8.View/Download from: Publisher's site
Mechanisms of protein misfolding are of increasing interest in the aetiology of neurodegenerative diseases characterized by protein aggregation and tangles including Amyotrophic Lateral Sclerosis (ALS), Alzheimer's disease (AD), Parkinson's disease (PD),
Chan, S, Dunlop, RA, Rowe, A, Double, KL & Rodgers, K 2012, 'L-DOPA is incorporated into brain proteins of patients treated for Parkinson's disease, inducing toxicity in human neuroblastoma cells in vitro', Experimental Neurology, vol. 238, no. 1, pp. 29-37.View/Download from: Publisher's site
Levodopa (l-dopa), a close structural analogue of the protein amino acid l-tyrosine, can substitute for l-tyrosine in protein synthesis and be mistakenly incorporated into newly synthesised proteins in vitro. We show that l-dopa-containing proteins are present in the brain in l-DOPA-treated Parkinson's disease patients and accumulate in specific brain regions. In vitro studies demonstrate that substitution of l-tyrosine residues in proteins with l-DOPA causes protein misfolding and promotes protein aggregation in SH-SY5Y neuroblastoma cells resulting in the appearance of autofluorescent bodies. We show that the presence of l-DOPA-containing proteins causes profound changes in mitochondria and stimulates the formation of autophagic vacuoles in cells. Unlike l-DOPA, which is toxic to cells through its ability to generate radicals, proteins containing incorporated l-DOPA are toxic to SH-SY5Y cells by a mechanism independent of oxidative stress and resistant to antioxidants. These data suggest that the accumulation of l-DOPA-containing proteins in vulnerable cells might negatively impact on cell function.
Dunlop, RA, Brunk, UT & Rodgers, K 2011, 'Proteins containing oxidized amino acids induce apoptosis in human monocytes', Biochemical Journal, vol. 435, pp. 207-216.View/Download from: Publisher's site
Cellular deposits of oxidized and aggregated proteins are hallmarks of a variety of age-related disorders, but whether such proteins contribute to pathology is not well understood. We previously reported that oxidized proteins form lipofuscin/ceroid-like bodies with a lysosomal-type distribution and up-regulate the transcription and translation of proteolytic lysosomal enzymes in cultured J774 mouse macrophages. Given the recently identified role of lysosomes in the induction of apoptosis, we have extended our studies to explore a role for oxidized proteins in apoptosis. Oxidized proteins were biosynthetically generated in situ by substituting oxidized analogues for parent amino acids. Apoptosis was measured with Annexin-V/PI (propidium iodide), TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP nick-end labelling), MMP (mitochondrial membrane permeabilization), caspase activation and cytochrome c release, and related to lysosomal membrane permeabilization. Synthesized proteins containing the tyrosine oxidation product L-DOPA (L-3,4-dihydroxyphenylalanine) were more potent inducers of apoptosis than proteins containing the phenylalanine oxidation product o-tyrosine. Apoptosis was dependent upon incorporation of oxidized residues, as indicated by complete abrogation in cultures incubated with the non-incorporation control D-DOPA (D-3,4-dihydroxyphenylalanine) or when incorporation was competed out by parent amino acids. The findings of the present study suggest that certain oxidized proteins could play an active role in the progression of age-related disorders by contributing to LMP (lysosomal membrane permeabilization)-initiated apoptosis and may have important implications for the long-term use of L-DOPA as a therapeutic agent in Parkinson's disease
Gracanin, M, Lam, MA, Morgan, PE, Rodgers, K, Hawkins, CL & Davies, MJ 2011, 'Amino acid, peptide, and protein hydroperoxides and their decomposition products modify the activity of the 26S proteasome', Free Radical Biology & Medicine, vol. 50, no. 2, pp. 389-399.View/Download from: Publisher's site
Proteins are major biological targets for oxidative damage within cells because of their high abundance and rapid rates of reaction with radicals and singlet oxygen. These reactions generate high yields of hydroperoxides. The turnover of both native and modified/damaged proteins is critical for maintaining cell homeostasis, with this occurring via the proteasomal and endosomallysosomal systems; the former is of particular importance for intracellular proteins. In this study we have examined whether oxidation products generated on amino acids, peptides, and proteins modulate 26S proteasome activity. We show that oxidation products, and particularly protein hydroperoxides, are efficient inhibitors of the 26S proteasome tryptic and chymotryptic activities, with this depending, at least in part, on the presence of hydroperoxide groups. Removal of these species by reduction significantly reduces proteasome inhibition. This loss of activity is accompanied by a loss of thiol residues, but an absence of radical formation, consistent with molecular, rather than radical, reactions being responsible for proteasome inhibition. Aldehydes also seem to play a role in the inhibition of chymotryptic activity, with this prevented by treatment with NaBH4, which reduces these groups. Inhibition occurred at hydroperoxide concentrations of = 1 µM for oxidized amino acids and peptides and = 10 µM for oxidized proteins, compared with ca. 100 µM for H2O2, indicating that H2O2 is a much less effective inhibitor. These data indicate that the formation of oxidized proteins within cells may modulate cell function by interfering with the turnover of native proteins and the clearance of modified materials.
Reimers, GJ, Jackson, CL, Rickards, J, Chan, PY, Cohn, JS, Rye, K, Barter, PJ & Rodgers, K 2011, 'Inhibition of Rupture of Established Atherosclerotic Plaques by Treatment with Apolipoprotein A-I', Cardiovascular Research, vol. 91, no. 1, pp. 37-44.View/Download from: Publisher's site
Aims Plasma concentrations of high-density lipoprotein (HDL)-cholesterol correlate inversely with the incidence of myocardial infarction in humans. We investigated the effect of treatment with human apolipoprotein A-I (apoA-I), the principal protein of HDL, on plaque disruption in an animal model. Methods and results Seventy apolipoprotein E knockout mice were induced to develop atherosclerotic lesions in the brachiocephalic artery by feeding a high-fat diet for 9 weeks. Mice then received twice-weekly treatment with human apoA-I (8 mg/kg) or vehicle, for 2 weeks. The incidence of acute plaque disruption was reduced by 65% in mice receiving apoA-I (P < 0.01). Plaques in treated mice had a more stable phenotype, with an increase in smooth muscle cell (SMC): macrophage ratio (P = 0.05), principally the consequence of an increase in the number of SMC in plaques. In the fibrous cap, there were reductions in matrix metalloproteinase-13 (-69%, P < 0.0001) and S100A4, a marker of SMC de-differentiation (-60%, P < 0.0001). These results indicate that 2 weeks of treatment with small amounts of human apoA-I produces more stable plaques in a mouse model.
Tang, J, Dunlop, RA, Rowe, A, Rodgers, K & Ramzan, I 2011, 'Kavalactones yangonin and methysticin induce apoptosis in human hepatocytes (HepG2) in vitro', Phytotherapy Research, vol. 25, no. 3, pp. 417-423.View/Download from: Publisher's site
While cases of severe kava hepatotoxicity have been reported, studies examining the toxicity of individual kavalactones are limited. The present study examined the in vitro hepatotoxicity of kavain, methysticin and yangonin on human hepatocytes (HepG2) and the possible mechanism(s) involved. Cytotoxicity was assessed using lactate dehydrogenase (LDH) and ethidium bromide (EB) assays. The mode of cell death was analysed with acridine orange/ethidium bromide dual staining with fluorescence microscopy. Glutathione oxidation was measured using the ortho-phthalaldehyde (OPT) fluorescence assay. Kavain had minimal cytotoxicity, methysticin showed moderate concentration-dependent toxicity and yangonin displayed marked toxicity with ~40% reduction in viability in the EB assay. Acridine orange/ethidium bromide staining showed the predominant mode of cell death was apoptosis rather than necrosis. No significant changes were observed in glutathione levels, excluding this as the primary mechanism of cell death in this model. Further studies may elucidate the precise apoptotic pathways responsible and whether toxic kavalactone metabolites are involved.
Elevated levels of oxidized proteins are reported in diseased tissue from age-related pathologies such as atherosclerosis, neurodegenerative disorders, and cataract. Unlike the precise mechanisms that exist For the repair of nucleic acids, lipids, and ca
Organisms produce reactive species throughout their lives, and this may result in damage to proteins and other biological molecules. Oxidatively damaged proteins are normally selectively degraded and replaced, but this process appears to be less efficien
Thompson, AM, Dunlop, RA, Dean, R & Rodgers, K 2009, 'Evidence that DOPA-derivatives are generated after L-DOPA incorporation into proteins by mammalian cells', Journal Of Adhesion, vol. 85, no. 9, pp. 561-575.View/Download from: Publisher's site
The adhesive and cohesive properties of the amino acid L-3,4-dihydroxyphenylalanine (DOPA) have been widely explored as a potential material for adhesion, based, among other things, on the biological system of blue mussel extracellular byssal threads and
Dunlop, RA, Dean, R & Rodgers, K 2008, 'The impact of specific oxidized amino acids on protein turnover in J774 cells', Biochemical Journal, vol. 410, no. 1, pp. 131-140.View/Download from: Publisher's site
Oxidized protein deposition and accumulation have been implicated in the aetiology of a wide variety of age-related pathologies. Protein oxidation in vivo commonly results in the in situ modification of amino acid side chains, generating new oxidized ami
Rodgers, K & Shiozawa, N 2008, 'Misincorporation of amino acid analogues into proteins by biosynthesis', International Journal of Biochemistry & Cell Biology, vol. 40, no. 8, pp. 1452-1466.View/Download from: Publisher's site
Despite astounding diversity in their structure and function, proteins are constructed from 22 protein or 'canonical' amino acids. Hundreds of amino acid analogues exist; many occur naturally in plants, some are synthetically produced or can be produced
Headlam, H, Gracanin, M, Rodgers, K & Davies, MJ 2006, 'Inhibition of cathepsins and related proteases by amino acid, peptide, and protein hydroperoxides', Free Radical Biology & Medicine, vol. 40, no. 9, pp. 1539-1548.View/Download from: Publisher's site
Reaction of radicals ill the presence Of O-2, and singlet oxygen, with some amino acids, peptides, and proteins yields hydroperoxides. These species are key intermediates in chain reactions and protein damage. Previously we have shown that peptide and pr
Rodgers, K, Hume, P, Morris, J & Dean, R 2006, 'Evidence for L-dopa incorporation into cell proteins in patients treated with levodopa', Journal of Neurochemistry, vol. 98, no. 4, pp. 1061-1067.View/Download from: Publisher's site
Levodopa (L-dopa) is the most widely used agent for the symptomatic relief of Parkinson's disease. There is concern that chronic L-dopa treatment may be detrimental, with some studies suggesting that L-dopa may be neurotoxic. A potentially important mech
Rodgers, K, Watkins, D, Miller, A, Chan, P, Karanam, S, Brissette, W, Long, C & Jackson, C 2006, 'Destabilizing role of cathepsin S in murine atherosclerotic plaques', Arteriosclerosis Thrombosis And Vascular Biology, vol. 26, no. 4, pp. 851-856.View/Download from: Publisher's site
Objective - Lysosomal proteinases have been implicated in a number of pathologies associated with extracellular matrix breakdown. Therefore, we investigated the possibility that the lysosomal proteinase cathepsin S may be involved in atherosclerotic plaq
Zeng, J, Dunlop, RA, Rodgers, K & Davies, MJ 2006, 'Evidence for inactivation of cysteine proteases by reactive carbonyls via glycation of active site thiols', Biochemical Journal, vol. 398, no. 2, pp. 197-206.
Hyperglycaemia, triose phosphate decomposition and oxidation reactions generate reactive aldehydes in vivo. These compounds react non-enzymatically with protein side chains and N-terminal amino groups to give adducts and cross-links, and hence modified p
Ozawa, K, Headlam, M, Mouradov, D, Watt, S, Beck, J, Rodgers, K, Dean, R, Huber, T, Otting, G & Dixon, N 2005, 'Translational incorporation of L-3,4-dihydroxyphenylalanine into proteins', FEBS Journal, vol. 272, no. 12, pp. 3162-3171.View/Download from: Publisher's site
An Escherichia coli cell-free transcription/translation system was used to explore the high-level incorporation Of L-3,4-dihydroxyphenylalanine (DOPA) into proteins by replacing tyrosine with DOPA in the reaction mixtures. ESI-MS showed specific incorpor
Rodgers, K, Hume, P, Dunlop, RA & Dean, R 2004, 'Biosynthesis and turnover of DOPA-containing proteins by human cells', Free Radical Biology & Medicine, vol. 37, no. 11, pp. 1756-1764.View/Download from: Publisher's site
Protein-bound 3,4-dihydroxyphenylalanine (PB-DOPA) is a major product of hydroxyl radical attack on tyrosine residues of proteins. Levels of PB-DOPA in cells and tissues have been shown to be greatly elevated in age-related diseases. We demonstrate for t
Dean, R, Dunlop, RA, Hume, P & Rodgers, K 2003, 'Proteolytic 'defences' and the accumulation of oxidized polypeptides in cataractogenesis and atherogenesis', Biochemical Society Symposium, vol. 70, no. 1, pp. 135-146.
Over the last few years, it has been clearly established that normal plasma contains low levels of oxidized polypeptides, and that these accumulate in tissues during several age-related pathologies. In contrast, normal mammalian aging, contrary to conven
Rodgers, K & Dean, R 2003, 'Assessment of proteasome activity in cell lysates and tissue homogenates using peptide substrates', International Journal of Biochemistry & Cell Biology, vol. 35, no. 5, pp. 716-727.View/Download from: Publisher's site
The ubiquitin-proteasome pathway is a major route of degradation of cell proteins. It also plays an essential role in maintaining cell homeostasis by degrading many rate-limiting enzymes and critical regulatory proteins. Alterations in proteasome activit
Dunlop, RA, Rodgers, K & Dean, R 2002, 'Recent developments in the intracellular degradation of oxidized proteins', Free Radical Biology & Medicine, vol. 33, no. 7, pp. 894-906.View/Download from: Publisher's site
The accumulation of oxidized proteins in cells and tissues is a feature of a number of age-related diseases and may also occur as a result of the aging process itself. In this article we review recent advances in our understanding of the cellular degrada
Rodgers, K, Wang, H, Fu, S & Dean, R 2002, 'Biosynthetic incorporation of oxidized amino acids into proteins and their cellular proteolysis', Free Radical Biology & Medicine, vol. 32, no. 8, pp. 766-775.View/Download from: Publisher's site
We demonstrate that oxidized amino acids can be incorporated into proteins by protein synthesis. The level of incorporation into protein was dependent on the concentration of oxidized amino acid supplied to the cells. At low levels of incorporation, the oxidized amino acids examined increased the degradation rate of the cell proteins. Degradation of certain proteins containing high levels of DOPA (but not ortho or meta tyrosine) was decreased to below the basal degradation rates suggesting that DOPA may contribute to proteins becoming resistant to proteolysis. Changes in the degradation rates of the oxidized amino acid-containing proteins was shown to have no impact on the degradation rates of native proteins, indicating that the activity of the degradative machinery was not affected. We demonstrate that oxidized proteins are selectively degraded by the proteasomes and provide evidence to suggest that the proteasomes and the endosomal-lysosomal systems may act in sequence as well as in parallel. The incorporation approach, unlike cell studies in which an exogenous oxidant is used, allows the degradation rates of the oxidatively modified proteins to be selectively measured, offering a greater sensitivity as well as greatly reducing toxicity to the cell and avoiding oxidative modification of other cell components.
Melrose, J, Smith, S, Rodgers, K, Little, C, Burkhardt, D & Ghosh, P 2000, 'Immunolocalisation of BPTI-like serine proteinase inhibitory proteins in mast cells, chondrocytes and intervertebral disc fibrochondrocytes of ovine and bovine connective tissues. An immunohistochemical and biochemical study', Histochemistry and Cell Biology, vol. 114, no. 2, pp. 137-146.View/Download from: Publisher's site
A polyclonal anti-bovine pancreatic trypsin inhibitor (BPTI) IgY was raised in chickens immunised with aprotinin The anti-BPTI IgY was subsequently isolated lated from egg yolks and purified to homogeneity by affinity chromatography on immobilised aproti
Protein-bound 3,4-dihydroxyphenylalanine (DOPA) can be generated in mammalian cells by both controlled enzymatic pathways, and by uncontrolled radical reactions. Protein-bound DOPA (PB-DOPA) has reducing activity and the capacity to inflict secondary dam
Rodgers, KJ, Long, C & Jackson, C 1998, 'Cathepsins B, L and S may contribute to the rupture of human atherosclerotic plaques', Heart, vol. 79, no. SUPPL. 1.
Rupture of the fibrous cap of an atherosclerotic plaque may result in thrombosis and rapid occlusion of the artery. Since the most vulnerable areas of the plaque contain a large number of macrophages, it is thought that the release of matrix-degrading proteinases by these cells may contribute to the weakening and subsequent rupture of the fibrous cap. While a great deal of research has focused on matrix metalloproteinases, cysteine proteinases can also be secreted by activated macrophages. Cathepsin S is unique among the cysteine proteinases in that it is stable at neutral pH. Increased synthesis of cysteine proteinases may result in their secretion from the cell in the pro-form which, unlike the fully processed protein, is stable at neutral pH values. In this study, human atherosclerotic plaques obtained from carotid endarterectomy were dissected into defined regions. Cysteine proteinase levels in each region were assessed using peptide substrates, western blotting and zyrnography. Localisation of these proteinases was then examined histologically. Increased levels of cathepsins B, L and S were found in extracts of the shoulder region (up to 5 fold higher than normal arterial tissue) and close to the lipid core (up to 10 fold higher than normal arterial tissue). Histochemistry using an active site-directed probe revealed that the active proteinases were located in specific sites within these regions. These proteinases are highly active against many matrix molecules, and thus may produce focal weakening of the fibrous cap. Experiments are currently underway in which activated macrophages are incubated with plaque tissue and the effects of a range of proteinase inhibitors on the cleavage of specific matrix molecules examined.
Smith, M, Little, C, Rodgers, K & Ghosh, P 1997, 'Animal Models Used To Evaluate Anti-Osteoarthritis Drugs.', Pathologie Biologie, vol. 45, no. 4, pp. 313-320.
Naturally occuring osteoarthritis occurs in a variety of animal species including mice, guinea pigs, dogs and cynomolgus macaques and some of these animals have been used to evaluate the ability of anti-osteoarthritis drugs to reduce synovial inflammatio
Rodgers, K, Melrose, J & Ghosh, P 1996, 'Biotinylated trypsin and its application as a sensitive, versatile probe for the detection and characterisation of an ovine chondrocyte serine proteinase inhibitor using western blotting', Electrophoresis, vol. 17, no. 1, pp. 213-218.View/Download from: Publisher's site
Biotinylated trypsin (bT) was used as a probe on Western blots of 10-20% polyacrylamide gradient Tris-Tricine gels for the detection of serine proteinase inhibitors (SPIs) isolated from extracts of ovine articular cartilage and from chondrocyte condition
Rodgers, K, Melrose, J & Ghosh, P 1996, 'Purification and characterisation of 6 and 58 Kda forms of the endogenous serine proteinase inhibitory proteins of ovine articular cartilage', Biological Chemistry, vol. 377, no. 12, pp. 837-845.View/Download from: Publisher's site
The major ovine articular cartilage (AC) serine proteinase inhibitory protein (SPI), a 58 kDa glycoprotein (SPI-58), was purified to homogeneity by sequential Sephacryl S-300 gel permeation, concanavalin A affinity, Mono Q anion exchange and Superose 12
Rodgers, K, Melrose, J & Ghosh, P 1995, 'Biotin-labeled potato chymotrypsin inhibitor-1 - A useful probe for the detection and quantitation of chymotrypsin-like serine proteinases on western blots and its application in the detection of a serine proteinase synthesized by articular chondrocy', Analytical Biochemistry, vol. 227, no. 1, pp. 129-134.View/Download from: Publisher's site
Potato chymotrypsin inhibitor-1 (pCTI-1) was biotinylated by reaction with sulfosuccinimidyl-6-(biotinamido)hexanoate. This derivative was used as a probe on Western blots for the detection and quantitation of chymotrypsin and the detection of a chymotry
Melrose, J, Rodgers, K & Ghosh, P 1994, 'The preparation and use of biotinylated trypsin in western blotting for the detection of trypsin inhibitory proteins', Analytical Biochemistry, vol. 222, no. 1, pp. 34-43.View/Download from: Publisher's site
Methods were developed for the preparation of biotinylated trypsin of high specific activity. This was used as a probe for the detection of serine proteinase inhibitory proteins which had been separated by sodium dodecyl sulfate-polyacrylamide gradient s
Rodgers, KJ, Samardzic, K & Main, BJ 2015, 'Toxic Nonprotein Amino Acids' in Gopalakrishnakone, P, Carlini, CR & Ligabue-Braun, R (eds), Plant Toxins, Springer, Netherlands, pp. 1-20.View/Download from: Publisher's site
The 20 DNA-coded protein amino acids play central roles in the metabolism of most organisms. As well as being the building blocks for proteins, they play essential roles in a diverse range of metabolic pathways. They are estimated to be around 1000 molecules in nature, which share the same basic structure as these organic amino acids consisting of an α-carbon attached to a carboxyl group, an amino group, a hydrogen atom, and a unique side-chain group. Many “nonprotein” amino acids (NPAAs) are plant secondary metabolites.
In this chapter, the authors discuss plant NPAAs that have a similar chemical structure, size, shape, and charge to protein amino acids and can be mistakenly used in protein synthesis, interfere in biochemical pathways, overstimulate receptors, or chelate metal ions. Most often this results in some level of toxicity to the target organism and can confer some advantage to the plant. Toxic NPAAs might have evolved as defense chemicals that can be released into the soil to inhibit the growth of other plants or agents that can limit insect herbivory.
The effects of NPAAs on human health are not well understood. Consumption of a number of plants that contain NPAAs has been shown to have acutely toxic effects in humans. The key questions that remain unanswered are to what extent can NPAAs enter the food chain and what are the effects of a chronic low-level exposure to toxic plant NPAAs?
Melrose, J & Rodgers, KJ 1996, 'Preparation and Use of Biotinylated Probes for the Detection and Characterisation of Serine Proteinase and Serine Proteinase Inhibitory Proteins' in A Laboratory Guide to Biotin-Labeling in Biomolecule Analysis, Birkhäuser, pp. 143-165.
Fahrenholz, F. (Falk) OP772.B55.L33 1996 574. 19'26-dc2O Deutsche Bibliothek
Cataloging-in-Publication Data A laboratory guide to biotin-labeling in
biomolecule analysis / ed. by T. Meier; F. Fahrenholz. - Basel; Boston; Berlin:
Rodgers, K, Chan, S & Steele, J 2017, 'Administration of L-tyrosine with levodopa could be neuroprotective in Parkinson's disease', JOURNAL OF NEUROCHEMISTRY, Biennial Meeting of the International-Society-for-Neurochemistry and European-Society-for-Neurochemistry (ISN-ESN), WILEY, Paris, FRANCE, pp. 245-245.
Rodgers, K, Steele, J & Padula, M 2017, 'A novel approach to detect the presence of levodopa (lDOPA) in the polypeptide chains of proteins', JOURNAL OF NEUROCHEMISTRY, Biennial Meeting of the International-Society-for-Neurochemistry and European-Society-for-Neurochemistry (ISN-ESN), WILEY, Paris, FRANCE, pp. 164-164.
Geronimo, FRB, Barter, PJ, Rye, K-A & Rodgers, KJ 2010, 'Short-Term Intravenous Injections of Human Lipid-Free Apolipoprotein A-IV Reduced Inflammation, Oxidation, and Apoptosis and Improved Plaque Stability in Brachiocephalic Artery Atheromas in Apo E-Null Mice', ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY, pp. E193-E193.
Gracanin, M, Rodgers, KJ, Hawkins, CL & Davies, MJ 2009, 'Amino Acids, Peptide and Protein Hydroperoxides, and their Decomposition Products, Modify the Activity of the 26S Proteasome', FREE RADICAL BIOLOGY AND MEDICINE, pp. S121-S121.
Chan, PY, Dunlop, RA & Rodgers, KJ 2006, 'Accumulation of hypochlorite modified LDL by human monocyte-derived macrophages causes a selective increase in expression of the cathepsin S gene.', FREE RADICAL RESEARCH, pp. S107-S107.
Dunlop, RA, Dean, RT & Rodgers, KJ 2006, 'Proteins containing incorporated DOPA are inefficiently degraded by proteasomes and can upregulate lysosomal proteinases.', FREE RADICAL RESEARCH, pp. S53-S53.
Shiozawa, N & Rodgers, KJ 2006, 'Comparison of the gene expression profiles of different cell lines in response to oxidatively modified proteins.', FREE RADICAL RESEARCH, pp. S85-S85.
Rodgers, KJ, Dunlop, RA & Dean, RT 2005, 'A novel approach to determine the pathways involved in the cellular catabolism of oxidised proteins', FREE RADICAL RESEARCH, pp. S74-S74.
Learner-Generated Digital Media (LGDM) has been incorporated as a tool to assess students in K-12 and higher education in the last decade. There are frameworks developed for video making in the classroom that considers technical know-how and a model that incorporate pedagogies. However, there is the absence of a practical framework to inform academics and students on the implementation of digital presentations as an assessment tool in the curricula. The aim of this poster is to propose a model for how to design, implement and evaluate LGDM as assessment tools in tertiary education. This evidence-based framework considers the following elements: (1) pedagogy; (2) student training; (3) hosting of videos; (4) marking schemes; (5) group contribution; (6) feedback; (7) reflection, and; (8) evaluation. The model serves as a conduit between theory and good practice.