G S Robertson

Dalhousie University, Halifax, Nova Scotia, Canada

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Publications (89)406.24 Total impact

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    ABSTRACT: Previously, we showed that age-related hearing loss (AHL) was delayed in C57BL6 mice overexpressing X-Linked Inhibitor of Apoptotic Protein (XIAP), and the delayed AHL was associated with attenuated hair cell (HC) loss in XIAP-overexpressing mice. Similar to other reports, the HC loss in aged mice was restricted to the basal turn in this previous study, and occurred slightly at the apical end of the cochlea, showing considerably less spread than the frequency region of hearing loss. In the present study, we examined whether and how AHL is related to the degeneration of neuronal innervation of the cochlea and whether the overexpression of XIAP exerts a protective effect against age-related degeneration in both afferent and efferent cochlear neurites. In contrast to HC loss, degeneration of both afferent and efferent neurites spread to the middle turns of the cochlea. Moreover, XIAP-overexpressing mice lost fewer HC afferent dendrites and efferent axons, as well as fewer spiral ganglion neurons between 3 and 14 months of age in comparison with wild-type littermates. The results suggest that age-related degeneration of cochlear neurites may be independent of HC loss. Further, the inhibition of apoptosis by XIAP appears to reduce degeneration of both afferent and efferent cochlear neurites.Gene Therapy advance online publication, 21 August 2014; doi:10.1038/gt.2014.77.
    Gene Therapy 08/2014; · 4.20 Impact Factor
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    ABSTRACT: The anti-inflammatory and restorative effects of the flavonoid-enriched fraction AF4 were examined in a mouse model of experimental autoimmune encephalomyelitis (EAE). Relative to EAE mice that received vehicle (water, 10 ml/kg/day), oral administration of AF4 (25 mg/kg/day) beginning 24 hours after the onset of clinical signs reduced disease severity from days 19–31 post-immunization. AF4-mediated recovery from EAE was preceded by reduced plasma concentrations of TNFα and IL-1β at day 18 followed by decreased cytokine production and neuropathology in the cerebellum and spinal cord at day 31. Clinical improvement for EAE-AF4 mice from days 18 to 31 was accompanied by the elevated expression of genes that mediate remyelination. These findings suggest AF4 decreased EAE severity by promoting the resolution of inflammation and improving functional recovery in the CNS.
    Journal of neuroimmunology 03/2014; · 2.84 Impact Factor
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    ABSTRACT: Transcriptional dysregulation is a major pathological feature of Huntington's disease (HD). The goal of this study was to understand how p65/RelA co-regulated genes, specifically those of the cytokine and endocannabinoid systems, were affected in HD. p65/RelA levels were lower in human HD tissue and R6/2 HD mice, as were the levels of the type 1 cannabinoid receptor (CB1), IL-1β, IL-8, CCL5, GM-CSF, MIP-1β, and TNFα, all of which may be regulated by p65/RelA. Activation of p65/RelA restored CB1 and CCL5 expression in STHdh cell models of HD. Therefore, p65/RelA activation may normalize the expression of some genes in HD.
    Journal of neuroimmunology 12/2013; · 2.84 Impact Factor
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    ABSTRACT: An altered polyamine system has been suggested to play a key role in mood disorders and suicide, a hypothesis corroborated by the evidence that lithium inhibits the polyamine mediated stress response in the rat brain. Recent post-mortem studies have shown that spermidine/spermine N1-acetyltransferase (SAT1), the key regulator of cellular polyamine content, is under-expressed in brains from suicide victims compared to controls. In our study we tested the effect of in vitro lithium treatment on SAT1 gene and protein expression in B lymphoblastoid cell lines (BLCLs) from bipolar disorder (BD) patients who committed suicide (and for which BLCLs were collected prior to their death), BD patients with high and low risk of suicide and a sample of non-psychiatric controls. Baseline mRNA levels were similar in the four groups of subjects (p > 0.05). Lithium had no effect in suicide completers (p > 0.05) while it significantly increased SAT1 expression in the high risk (p < 0.001) and low risk (p < 0.01) groups as well as in controls (p < 0.001). Protein and mRNA levels were not correlated; lithium significantly reduced protein levels only in the control sample (p < 0.05). Our findings suggest that SAT1 transcription is influenced by lithium and that this effect is altered in BD patients who completed suicide, further supporting a role for polyamines in suicide.
    The International Journal of Neuropsychopharmacology 06/2013; · 5.64 Impact Factor
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    ABSTRACT: X-linked inhibitor of apoptosis (XIAP) protects and preserves the function of neurons in both in vitro and in vivo models of excitotoxicity. Since calcium (Ca(2+)) overload is a pivotal event in excitotoxic neuronal cell death, we have determined whether XIAP over-expression influences Ca(2+)-signaling in primary cultures of mouse cortical neurons. Using cortical neuron cultures derived from wild-type (Wt) mice transiently transfected with XIAP or from transgenic mice that over-express XIAP, we show that XIAP opposes the rise in intracellular Ca(2+) concentration by a variety of triggers. Relative to control neurons, XIAP over-expression produced a slight, but significant, elevation of resting Ca(2+) concentrations. By contrast, the rise in intracellular Ca(2+) concentrations produced by N-methyl-D-aspartate receptor stimulation and voltage gated Ca(2+) channel activation were markedly attenuated by XIAP over-expression. The release of Ca(2+) from intracellular stores induced by the sarco/endoplasmic reticulum Ca(2+) ATPase inhibitor thapsigargin was also inhibited in neurons transiently transfected with XIAP. The pan-caspase inhibitor zVAD did not, however, diminish the rise in intracellular Ca(2+) concentrations elicited by L-glutamate suggesting that XIAP influences Ca(2+) signaling in a caspase-independent manner. Taken together, these findings demonstrate that the ability of XIAP to block excessive rises in intracellular Ca(2+) by a variety of triggers may contribute to the neuroprotective effects of this anti-apoptotic protein.
    Neurochemical Research 02/2013; · 2.55 Impact Factor
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    ABSTRACT: We report here neuroprotective and anti-inflammatory effects of a flavonoid-enriched fraction isolated from the peel of Northern Spy apples (AF4) in a mouse of model of hypoxic-ischemic (HI) brain damage. Oral administration of AF4 (50 mg/kg, once daily for 3 days) prior to 50 min of HI completely prevented motor performance deficits assessed 14 days later that were associated with marked reductions in neuronal cell loss in the dorsal hippocampus and striatum. Pre-treatment with AF4 (5, 10, 25 or 50 mg/kg, p.o.; once daily for 3 days) produced a dose-dependent reduction in HI-induced hippocampal and striatal neuron cell loss, with 25 mg/kg being the lowest dose that achieved maximal neuroprotection. Comparison of the effects of 1, 3 or 7 doses of AF4 (25 mg/kg; p.o.) prior to HI revealed that at least 3 doses of AF4 were required before HI to reduce neuronal cell loss in both the dorsal hippocampus and striatum. Quantitative RT-PCR measurements revealed that the neuroprotective effects of AF4 (25 mg/kg; p.o.; once daily for 3 days) in the dorsal hippocampus were associated with a suppression of HI-induced increases in the expression of IL-1β, TNF-α and IL-6. AF4 pre-treatment enhanced mRNA levels for pro-survival proteins such as X-linked inhibitor of apoptosis and erythropoietin following HI in the dorsal hippocampus and striatum, respectively. Primary cultures of mouse cortical neurons incubated with AF4 (1 µg/ml), but not the same concentrations of either quercetin or quercetin-3-O-glucose or its metabolites, were resistant to cell death induced by oxygen glucose deprivation. These findings suggest that the inhibition of HI-induced brain injury produced by AF4 likely involves a transcriptional mechanism resulting from the co-operative actions of various phenolics in this fraction which not only reduce the expression of pro-inflammatory mediators but also enhance pro-survival gene signalling.
    PLoS ONE 12/2012; 7(12):e51324. · 3.53 Impact Factor
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    ABSTRACT: Habitual consumption of dietary flavonoids known to improve mitochondrial bioenergetics and inhibit various secondary sources of reactive oxygen species (ROS) reduces the risk for neurodegenerative disorders such as Parkinson's disease (PD), stroke, and Alzheimer's disease (AD). Combining specific dietary flavonoids selected on the basis of oral bioavailability, brain penetration, and the inhibition of multiple processes responsible for excessive ROS production may be a viable approach for the prevention and treatment of neurodegenerative disorders. Inclusion of flavonoids that raise cAMP levels in the brain may be of additional benefit by reducing the production of proinflammatory mediators and stimulating the transcriptional machinery necessary for mitochondrial biosynthesis. Preclinical models suggest that flavonoids reduce hearing loss resulting from treatment with the chemotherapeutic drug cisplatin by opposing the excessive production of ROS and proinflammatory mediators implicated in PD, stroke, and AD. Flavonoid combinations optimized for efficacy in models of cisplatin-induced hearing loss (CIHL) may therefore have therapeutic utility for neurodegenerative disorders.
    Trends in Pharmacological Sciences 09/2012; 33(11):602-10. · 9.99 Impact Factor
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    ABSTRACT: Potato (Solanum tuberosum L.) is one of the most important food crops in the world and provides essential nutrients. With an aim to develop potato varieties for functional food or nutraceutial applications, we have conducted metabolomic profiling, total phenolics, chlorogenic acid, anthocyanins, and glycoalkaloids analyses on 20 selected potato clones within the Canadian potato breeding program of Agriculture and Agri-Food Canada. Pigmented potatoes in general contain higher levels of phenolic components, including chlorogenic acid and anthocyanins. Levels of phenolics were retained with granulation processing of pigmented potato tubers, but glycoalkaloids were significantly reduced with granulation. The pigmented potatoes also have higher antioxidant activity reaching up to 35% of that for berries, measured as their potency in scavenging DPPH radicals. Extracts of the 20 potato clones (peel, tuber, and granule) were also evaluated for in vitro effects on liver LDL cholesterol uptake and protection of cortical neurons from cell death caused by oxygen glucose deprivation (OGD). These potato extracts in general showed mild activity in enhancing LDL cholesterol uptake in liver HepG2 cells, and also protected cortical neurons against OGD induced cell death, with extracts from granules of six of the potato clones showing significant neuroprotective effects. The bioactive components are not dependent on pigmentation of potato clones. These novel bioactivities identified in potatoes warrant in-depth investigations in the future. Taken together, our results provide further evidence for the enhanced health beneficial components in potato.
    Food Chemistry 08/2012; 133(4):1177-1187. · 3.26 Impact Factor
  • George S Robertson, Kosuke Kajitani
    Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology 03/2012; 37(4):1075. · 8.68 Impact Factor
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    Jordan Warford, George S Robertson
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    ABSTRACT: Introduction: MS is a heterogeneous disorder that requires the development of better diagnostics to identify disease subtypes enabling appropriate therapeutic intervention at an early stage of the disease. Accumulating evidence indicates that members of the inhibitor of apoptosis (IAP) family play an important role in the pathogenesis of MS by reducing the apoptotic elimination of autoreactive immune cells. Areas covered: The authors describe improved animal modeling strategies to identify compounds that have immunomodulatory, neurorestorative and neuroprotective properties. In addition, the authors propose new approaches to better model cognitive dysfunction in MS, which will aid the development of novel therapeutics for this complex disorder. The paper provides the reader with an appreciation for the diagnostic and therapeutic potential of apoptosis-related proteins for MS. Expert opinion: Recent evidence suggests that increased resistance of autoreactive immune cells to apoptotic elimination is a contributing factor to both disease susceptibility and progression in MS. This occurs, at least in part, because of elevated levels of the IAP family of anti-apoptotic genes that display distinct expression profiles associated with different subtypes of MS. The authors believe that the detection and targeting of members of the IAP family can provide better drugs for MS. Particularly, the authors feel that the overexpression of IAPs in animal models can provide novel insights into MS for both its pathogenesis and the discovery of new lead compounds.
    Expert Opinion on Drug Discovery 07/2011; 6(7):689-99. · 3.47 Impact Factor
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    ABSTRACT: The auditory portion of the inner ear, the cochlea, is an ideal organ for local gene transfection owing to its relative isolation. Various carriers have been tested for cochlear gene transfection. To date, viral vectors appear to have much higher transfection efficacy than non-viral mechanisms. Among these vectors, recombinant adeno-associated virus (rAAV) vectors have several advantages such as being non-pathogenic and the ability to produce prolonged gene expression in various cell types. However, rAAV vectors cannot pass through the intact round window membrane (RWM), otherwise a very attractive approach to access the human inner ear. In this study, performed in guinea-pigs, we describe a method to increase the permeability of RWM to rAAV vectors by partial digestion with collagenase solution. Elevated delivery of rAAV across the partially digested RWM increased transfection efficacy to a satisfactory level, even though it was still lower than that achieved by direct cochleostomy injection. Functional tests (auditory brainstem responses) showed that this enzymatic manipulation did not cause permanent hearing loss if applied appropriately. Morphological observations suggested that the damage to RWM caused by partial digestion healed within four weeks. Taken together, these findings suggest that partial digestion of the RWM is a safe and effective method for increasing the transfection of cochlear sensory cells with rAAV.
    Gene therapy 06/2011; 19(3):255-63. · 4.75 Impact Factor
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    ABSTRACT: Parkinson's disease (PD) results from the loss of dopamine neurons located in the substantia nigra pars compacta (SNpc) that project to the striatum. A therapeutic has yet to be identified that halts this neurodegenerative process, and as such, development of a brain penetrant small molecule neuroprotective agent would represent a significant advancement in the treatment of the disease. To fill this void we developed an aminopyrimidine JNK inhibitor (SR-3306) that reduced the loss of dopaminergic cell bodies in the SNpc and their terminals in the striatum produced by unilateral injection of 6-hydroxydopamine (6-OHDA) into the nigrostriatal pathway. Administration of SR-3306 [10 mg/kg/day (s.c.) for 14 days] increased the number of tyrosine hydroxylase immunoreactive (TH(+)) neurons in the SNpc by six-fold and reduced the loss of the TH(+) terminals in the striatum relative to the corresponding side of 6-OHDA-lesioned rats that received only vehicle (p<0.05). In addition, SR-3306 [10 mg/kg/day (s.c.) for 14 days] decreased d-amphetamine-induced circling by 87% compared to 6-OHDA-lesioned animals given vehicle. Steady-state brain levels of SR-3306 at day 14 were 347 nM, which was approximately two-fold higher than the cell-based IC(50) for this compound. Finally, immunohistochemical staining for phospho-c-jun (p-c-jun) revealed that SR-3306 [10 mg/kg/day (s.c.) for 14 days] produced a 2.3-fold reduction of the number of immunoreactive neurons in the SNpc relative to vehicle treated rats. Collectively, these data suggest that orally bioavailable JNK inhibitors may be useful neuroprotective agents for the treatment of Parkinson's disease.
    ACS Chemical Neuroscience 04/2011; 2(4):207-212. · 4.21 Impact Factor
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    J Wang, N Tymczyszyn, Z Yu, S Yin, M Bance, G S Robertson
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    ABSTRACT: Apoptosis is responsible for cochlear cell death induced by noise. Here, we show that transgenic (TG) mice that overexpress X-linked inhibitor of apoptosis protein (XIAP) under control of the ubiquitin promoter display reduced hearing loss and cochlear damage induced by acoustic overstimulation (125 dB sound pressure level, 6 h) compared with wild-type (WT) littermates. Hearing status was evaluated using the auditory brainstem response (ABR), whereas cochlear damage was assessed by counts of surviving hair cells (HCs) and spiral ganglion neurons (SGNs) as well as their fibers to HCs. Significantly smaller threshold shifts were found for TG mice than WT littermates. Correspondingly, the TG mice also showed a reduced loss of HCs, SGNs and their fibers to HCs. HC loss was limited to the basal end of the cochlea that detects high frequency sound. In contrast, the ABRs demonstrated a loss of hearing sensitivity across the entire frequency range tested (2-32 kHz) indicating that the hearing loss could not be fully attributed to HC loss alone. The TG mice displayed superior hearing sensitivity over this whole range, suggesting that XIAP overexpression reduces noise-induced hearing loss not only by protecting HCs but also other components of the cochlea.
    Gene therapy 01/2011; 18(6):560-8. · 4.75 Impact Factor
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    ABSTRACT: STOP (stable tubule only polypeptide) null mice display neurochemical and behavioral abnormalities that resemble several well-recognized features of schizophrenia. Recent evidence suggests that the hematopoietic growth factor erythropoietin improves the cognitive performance of schizophrenics. The mechanism, however, by which erythropoietin is able to improve the cognition of schizophrenics is unclear. To address this question, we first determined whether acute administration of the erythropoietin analog known as darbepoetin alfa (D. alfa) improved performance deficits of STOP null mice in the novel objective recognition task (NORT). NORT performance of STOP null mice, but not wild-type littermates, was enhanced 3 h after a single injection of D. alfa (25 μg/kg, i.p.). Improved NORT performance was accompanied by elevated NADPH diaphorase staining in the ventral hippocampus as well as medial and cortical aspects of the amygdala, indicative of increased nitric oxide synthase (NOS) activity in these structures. NOS generates the intracellular messenger nitric oxide (NO) implicated in learning and memory. In keeping with this hypothesis, D. alfa significantly increased NO metabolite levels (nitrate and nitrite, NOx) in the hippocampus of both wild-type and STOP null mice. The NOS inhibitor, N (G)-nitro-L- arginine methyl ester (L-NAME; 25 mg/kg, i.p.), completely reversed the increase in hippocampal NOx levels produced by D. alfa. Moreover, L-NAME also inhibited the ability of D. alfa to improve the NORT performance of STOP null mice. Taken together, these observations suggest D. alfa enhances the NORT performance of STOP null mice by increasing production of NO.
    Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology 08/2010; 35(9):2005. · 8.68 Impact Factor
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    ABSTRACT: In the present study, we compared the expression of cyclin D2 and D2SV, the cyclin D2 splice variant, in mouse cerebellum at postnatal day 1 (P1), P7, P14 and P28. Western blotting revealed that cyclin D2 levels (34kDa) peaked at P7 and then decreased to levels near the limit of detection at P28. To detect D2SV, we generated a rabbit polyclonal antibody directed against a C-terminal motif unique to this protein that recognizes two D2SV immunoreactive bands at 20 and 25kDa. Western blotting indicated that levels of the 20kDa band remained constant from P1 to P28 while the intensity of the 25kDa band decreased gradually over this period of time. At P7, cyclin D2 immunoreactivity was evident throughout the cerebellum where it was located in nestin-positive cells. By contrast, at P28, cyclin D2 immunoreactivity was restricted to Bergmann glia whose cell bodies are located in the Purkinje cell layer and processes extend into the molecular layer. Unlike cyclin D2, D2SV immunoreactivity was restricted to Purkinje cells at both P7 and P28. Our observations that D2SV immunoreactivity is localized to Purkinje cells and reflects changing levels of at least two D2SV immunoreactive proteins suggests that this splice variant may play an important role in the postnatal development of these neurons.
    Neuroscience Letters 06/2010; 477(2):100-4. · 2.06 Impact Factor
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    ABSTRACT: The protease, human kallikrein-related peptidase 6 (hK6) is derived from activated macrophages in the central nervous system (CNS) and may contribute to pathology observed in multiple sclerosis (MS). In the present study, we compared serum and cerebrospinal fluid (CSF) protein concentrations of human kallikrein-related peptidase 6 derived from neurological controls and patients diagnosed with advanced multiple sclerotic disease. Mean serum levels of human kallikrein-related peptidase 6 were similar in neurological controls and patients diagnosed with relapsing-remitting (RR), secondary progressive (SP) and primary progressive (PP) multiple sclerosis with mean levels ranging from 3.5 to 3.75 ng/ml. Patients diagnosed with advanced multiple sclerosis showed mean CSF levels (29 ng/ml) that were significantly higher than neurological controls (25.5 ng/ml). Determining CSF concentrations of human kallikrein-related peptidase 6 may therefore have diagnostic value in MS.
    Current Drug Discovery Technologies 06/2010; 7(2):137-40.
  • Michel L Samson, Kosuke Kajitani, George S Robertson
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    ABSTRACT: Erythropoietin has been reported to improve the behavioral performance of healthy mice in tests thought to depend on synaptic plasticity in the CA1 region of the hippocampus. We show here for the first time that a single injection of the erythropoietin analog darbepoetin alfa reverses pre-existing cognitive deficits in adult rats that had been subjected to transient global ischemia produced by four-vessel occlusion (4-VO). Quantification of neuronal density demonstrated that 12 min of 4-VO selectively killed more than 90% of CA1 neurons in the dorsal hippocampus. Rats that had sustained a bilateral loss of hippocampal CA1 neurons in this range (4-VO rats) displayed more errors and longer escape latencies in the Barnes maze compared with sham-operated controls. A single injection of darbepoetin alfa (5000 U/kg i.p.) 4 h before behavioral testing decreased deficits in escape latency for 4-VO rats but not sham-operated controls. This improvement in spatial working memory performance was correlated with increased levels of nitric-oxide metabolites in the ventral hippocampus. Systemic administration of the nitric-oxide synthase inhibitor N(G)-nitro-L-nitro-arginine methyl ester reversed the increase in nitric-oxide metabolites and improvements in spatial working memory produced by darbepoetin alfa (5000 U/kg, i.p.) at a dose (10 mg/kg, i.p.) that did not impair the spatial working memory performance of intact rats. Taken together, these findings suggest that darbepoetin alfa reverses pre-existing spatial working memory deficits resulting from transient global ischemia by increasing the activity of nitric-oxide synthase, an enzyme implicated in synaptic plasticity.
    Journal of Pharmacology and Experimental Therapeutics 02/2010; 333(2):437-44. · 3.89 Impact Factor
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    ABSTRACT: Using quantitative RT-PCR, we compared mRNA levels for TRAIL [tumor necrosis factor (TNF)-related apoptosis-inducing ligand] and its receptors in various immune cell subsets derived from the peripheral blood of untreated normal subjects (NS) and patients with distinct subtypes of multiple sclerosis (MS): active relapsing-remitting MS (RRA), quiescent relapsing-remitting MS (RRQ), secondary-progressive MS (SPMS) or primary-progressive MS (PPMS). Consistent with a role for TRAIL in the mechanism of action of interferon-β (IFN-β), TRAIL mRNA levels were increased in monocytes from patients clinically responsive to IFN-β (RRQ) but not those unresponsive to this therapeutic (RRA). TRAIL-R3 (decoy receptor) expression was elevated in T cells from untreated RRMS patients while IFN-β therapy reversed this increase suggesting that IFN-β may promote the apoptotic elimination of autoreactive T cells by increasing the amount of TRAIL available to activate TRAIL death receptors. Serum concentrations of soluble TRAIL were increased to a similar extent by IFN-β therapy in RRQ, RRA and SPMS patients that had not generated neutralizing antibodies against this cytokine. Although our findings suggest altered TRAIL signaling may play a role in MS pathogenesis and IFN-β therapy, they do not support use of TRAIL as a surrogate marker for clinical responsiveness to this therapeutic.
    Autoimmune diseases. 01/2010; 2011:485752.
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    ABSTRACT: Triptolide, a diterpene triepoxide derived from Trypterygium wilfordii, is documented to have antitumor activity in a broad range of solid tumors and leukemia. The mechanisms that are involved in triptolide-mediated apoptosis or growth inhibition in cancer cells are not fully understood. We identified a disintegrin and metalloproteinase 10 (ADAM10) as a novel molecular target of triptolide using affinity chromatography and mass spectrometry. The identification was confirmed by western blot analysis using an anti-ADAM10 antibody. The expression of ADAM10 is enhanced in several tumors including leukemia and is involved in malignant cell growth and cancer progression. ADAM10 is a type 1 transmembrane glycoprotein that cleaves several plasma membrane proteins. We show that triptolide, at concentrations in the nM range, resulted in a significant decrease in ADAM10 expression followed by the appearance of ADAM10 cleaved product. Furthermore, triptolide reduced the viability of monocytic leukemic U937 cells. Triptolide treatment of MCF-7 breast cancer cells expressing ectopic ADAM10 or dominant negative ADAM10 (DN ADAM10) resulted in a decreased expression of ADAM10 with a concomitant increase in ADAM10 cleaved products. Moreover, siRNA-mediated knockdown of ADAM10 mRNA significantly affected the growth of MCF-7 cells. Interestingly, the combination of siRNA-mediated knockdown of ADAM10 mRNA expression and triptolide treatment lead to a further reduction in cell growth. Taken together, we provide evidence that ADAM10 is a novel target of triptolide, presenting a novel strategy to inhibit ADAM10 activity in tumorigenesis.
    Cancer biology & therapy 11/2009; 8(21):2054-62. · 3.29 Impact Factor
  • Michael Thorne, Craig S Moore, George S Robertson
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    ABSTRACT: Multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE) are both characterized by the infiltration of myelin-reactive T cells that trigger oligodendrocyte death associated with axonal loss and neurodegeneration in the CNS. Proteolysis of the cerebral vascular extracellular matrix (ECM) resulting in blood-brain barrier (BBB) breakdown is thought to facilitate infiltration of autoreactive T cells in both of these demyelinating disorders. Increased matrix metalloprotease (MMP) activity coupled with reduced levels of tissue inhibitor of metalloproteases (TIMPs) contribute to a loss of BBB integrity. Erythropoietin induces expression of TIMP-1 in endothelial cells suggesting this property may account in part for its ability to maintain BBB integrity and efficacy in a preliminary clinical MS trial. Consistent with this hypothesis, we report here that administration of the erythropoietin analogue darbepoetin alfa at a low dose that did not elevate hematocrit reduced EAE severity in female C57BL/6 mice when administered following the onset of clinical signs. The protective effects of darbepoetin alfa were associated with an increase in the number of astrocytes expressing TIMP-1 in the brain and spinal cord. In keeping with a central role for TIMP-1 in this autoimmune model of acute demyelination, TIMP-1 null mice displayed a more severe EAE phenotype than wild-type littermates. Interestingly, we observed a lack of effect of darbepoetin alfa on EAE severity in TIMP-1 null mice. These findings indicate that TIMP-1 deficiency both enhances disease severity and attenuates the beneficial effects of low dose darbepoetin alfa in a mouse model of EAE.
    Journal of neuroimmunology 06/2009; 211(1-2):92-100. · 2.84 Impact Factor

Publication Stats

3k Citations
406.24 Total Impact Points


  • 2007–2014
    • Dalhousie University
      • Department of Pharmacology
      Halifax, Nova Scotia, Canada
  • 2013
    • National Research Council Canada
      • Institute for Nutrisciences and Health (INH)
      Ottawa, Ontario, Canada
  • 2008
    • Shanghai Jiao Tong University
      Shanghai, Shanghai Shi, China
  • 2006
    • Central University of Venezuela
      • Facultad de Farmacia
      Caracas, Distrito Capital, Venezuela
  • 1993–2006
    • University of Ottawa
      • • Faculty of Medicine
      • • Department of Cellular and Molecular Medicine
      Ottawa, Ontario, Canada
  • 2002–2004
    • McGill University
      • Department of Pharmacology and Therapeutics
      Montréal, Quebec, Canada
  • 2000
    • Merck
      • Department of In Vitro Pharmacology
      Whitehouse Station, NJ, United States