Publications (58) View all
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Article: Stress-induced self-cannibalism: on the regulation of autophagy by endoplasmic reticulum stress.
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ABSTRACT: Macroautophagy (autophagy) is a cellular catabolic process which can be described as a self-cannibalism. It serves as an essential protective response during conditions of endoplasmic reticulum (ER) stress through the bulk removal and degradation of unfolded proteins and damaged organelles; in particular, mitochondria (mitophagy) and ER (reticulophagy). Autophagy is genetically regulated and the autophagic machinery facilitates removal of damaged cell components and proteins; however, if the cell stress is acute or irreversible, cell death ensues. Despite these advances in the field, very little is known about how autophagy is initiated and how the autophagy machinery is transcriptionally regulated in response to ER stress. Some three dozen autophagy genes have been shown to be required for the correct assembly and function of the autophagic machinery; however; very little is known about how these genes are regulated by cellular stress. Here, we will review current knowledge regarding how ER stress and the unfolded protein response (UPR) induce autophagy, including description of the different autophagy-related genes which are regulated by the UPR.Cellular and Molecular Life Sciences CMLS 09/2012; · 6.57 Impact Factor -
Article: Unfolded proteins and endoplasmic reticulum stress in neurodegenerative disorders.
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ABSTRACT: The stimuli for neuronal cell death in neurodegenerative disorders are multi-factorial and may include genetic predisposition, environmental factors, cellular stressors such as oxidative stress and free radical production, bioenergy failure, glutamate-induced excitotoxicity, neuroinflammation, disruption of Ca(2+) -regulating systems, mitochondrial dysfunction and misfolded protein accumulation. Cellular stress disrupts functioning of the endoplasmic reticulum (ER), a critical organelle for protein quality control, leading to induction of the unfolded protein response (UPR). ER stress may contribute to neurodegeneration in a range of neurodegenerative disorders. This review summarizes the molecular events occurring during ER stress and the unfolded protein response and it specifically evaluates the evidence suggesting the ER stress response plays a role in neurodegenerative disorders.Journal of Cellular and Molecular Medicine 07/2011; 15(10):2025-39. · 4.13 Impact Factor -
Article: Nerve Growth Factor in Cancer Cell Death and Survival
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ABSTRACT: One of the major challenges for cancer therapeutics is the resistance of many tumor cells to induction of cell death due to pro-survival signaling in the cancer cells. Here we review the growing literature which shows that neurotrophins contribute to pro-survival signaling in many different types of cancer. In particular, nerve growth factor, the archetypal neurotrophin, has been shown to play a role in tumorigenesis over the past decade. Nerve growth factor mediates its effects through its two cognate receptors, TrkA, a receptor tyrosine kinase and p75NTR, a member of the death receptor superfamily. Depending on the tumor origin, pro-survival signaling can be mediated by TrkA receptors or by p75NTR. For example, in breast cancer the aberrant expression of nerve growth factor stimulates proliferative signaling through TrkA and pro-survival signaling through p75NTR. This latter signaling through p75NTR promotes increased resistance to the induction of cell death by chemotherapeutic treatments. In contrast, in prostate cells the p75NTR mediates cell death and prevents metastasis. In prostate cancer, expression of this receptor is lost, which contributes to tumor progression by allowing cells to survive, proliferate and metastasize. This review focuses on our current knowledge of neurotrophin signaling in cancer, with a particular emphasis on nerve growth factor regulation of cell death and survival in cancer.Cancers. 01/2011; -
Article: The effects of cannabinoid drugs on abnormal involuntary movements in dyskinetic and non-dyskinetic 6-hydroxydopamine lesioned rats.
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ABSTRACT: The long-term use of levodopa as a pharmacotherapy for Parkinson's disease is limited by the development of levodopa-induced dyskinesias. However, recent studies have suggested that pharmacological targeting of the endocannabinoid system may provide a viable adjunct to suppress these motor side effects. Thus, this study sought to determine the effect of pharmacologically activating or blocking endocannabinoid signalling on levodopa-induced dyskinesias in a rat model. Male Sprague-Dawley rats with 6-hydroxydopamine lesions were made dyskinetic by 6 weeks of daily levodopa injections (10mg/kg s.c.). Rats that developed stable abnormal involuntary movements (AIMs) received acute injections of the cannabinoid receptor agonist, HU210 (0.0, 0.5, 5.0, and 50.0 μg/kg i.p.), or the CB(1) receptor antagonist/inverse agonist, AM251 (0.0 and 3.0mg/kg i.p.), whereas rats that did not develop stable AIMs received injections of the CB(1) receptor antagonist/inverse agonist, rimonabant (0.0 and 3.0mg/kg i.p.), for 18 days. In the dyskinetic rats, the highest dose of HU210 significantly reduced certain subtypes of AIMs but it also impaired normal motor functioning, while AM251 had no effect on AIMs. In the non-dyskinetic rats, rimonabant precipitated certain subtypes of AIMs. Overall, this study demonstrates that the anti-dyskinetic effects of cannabinoid receptor agonists may not be dissociable from their motor suppressant effects thereby limiting their potential usefulness for treating established dyskinesias in parkinsonism. However, it is intriguing that blockade of endocannabinoid-CB(1) signalling can unmask levodopa-induced AIMs, and this finding suggests that endocannabinoid tone may confer protection against the development of levodopa-induced dyskinesias.Brain research 09/2010; 1363:40-8. · 2.46 Impact Factor -
Article: Loss of cannabinoid CB1 receptor expression in the 6-hydroxydopamine-induced nigrostriatal terminal lesion model of Parkinson's disease in the rat.
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ABSTRACT: The endocannabinoid system is emerging as a potential alternative to the dopaminergic system for the treatment of Parkinson's disease. Like all emerging targets, validation of this system's potential for treating human Parkinsonism necessitates testing in animal models of the condition. However, if components of the endocannabinoid system are altered by the induction of a Parkinsonian state in animal models, this could have an impact on the interpretation of such preclinical experiments. This study sought to determine if expression of the CB(1) subtype of cannabinoid receptor is altered in the two most commonly used rat models of Parkinson's disease. Parkinsonian lesions were induced by stereotaxic injection of 6-hydroxydopamine into the axons (medial forebrain bundle) or terminals (striatum) of the nigrostriatal pathway. On days 1, 3, 7, 14 and 28 post-lesion, rats were sacrificed and brains were processed for tyrosine hydroxylase and CB(1) receptor immunohistochemistry. The CB(1) receptor was expressed strongly in the substantia nigra pars reticulata, minimally overlapping with tyrosine hydroxylase immunoreactivity in the pars compacta. Interestingly, while there was little change in CB(1) receptor expression following axonal lesion, expression of the receptor was significantly reduced following terminal lesion. Loss of CB(1) receptor expression in the pars reticulata correlated significantly with the loss of striatal and nigral volume after terminal lesion indicating this may have been due to 6-hydroxydopamine-induced non-specific damage of striatonigral neurons which are known to express CB(1) receptors. Thus, this result has implications for the choice of model and interpretation of studies used to investigate potential cannabinoid-based therapies for Parkinson's disease as well as striatonigral diseases such as Huntington's disease and Multiple Systems Atrophy.Brain research bulletin 04/2010; 81(6):543-8. · 2.18 Impact Factor
