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132 result(s) for "Jan, Asad"
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The Prion-Like Spreading of Alpha-Synuclein in Parkinson’s Disease: Update on Models and Hypotheses
The pathological aggregation of the presynaptic protein α-synuclein (α-syn) and propagation through synaptically coupled neuroanatomical tracts is increasingly thought to underlie the pathophysiological progression of Parkinson’s disease (PD) and related synucleinopathies. Although the precise molecular mechanisms responsible for the spreading of pathological α-syn accumulation in the CNS are not fully understood, growing evidence suggests that de novo α-syn misfolding and/or neuronal internalization of aggregated α-syn facilitates conformational templating of endogenous α-syn monomers in a mechanism reminiscent of prions. A refined understanding of the biochemical and cellular factors mediating the pathological neuron-to-neuron propagation of misfolded α-syn will potentially elucidate the etiology of PD and unravel novel targets for therapeutic intervention. Here, we discuss recent developments on the hypothesis regarding trans-synaptic propagation of α-syn pathology in the context of neuronal vulnerability and highlight the potential utility of novel experimental models of synucleinopathies.
OsTZF1, a CCCH-Tandem Zinc Finger Protein, Confers Delayed Senescence and Stress Tolerance in Rice by Regulating Stress-Related Genes
OsTZF1 is a member of the CCCH-type zinc finger gene family in rice (Oryza sativa). Expression of OsTZF1 was induced by drought, high-salt stress, and hydrogen peroxide. OsTZF1 gene expression was also induced by abscisic acid, methyl jasmonate, and salicylic acid. Histochemical activity of β-glucuronidase in transgenic rice plants containing the promoter of OsTZF1 fused with β-glucuronidase was observed in callus, coleoptile, young leaf, and panicle tissues. Upon stress, OsTZF1-green fluorescent protein localization was observed in the cytoplasm and cytoplasmic foci. Transgenic rice plants overexpressing OsTZF1 driven by a maize (Zea mays) ubiquitin promoter (Ubi:OsTZF1-OX [for overexpression]) exhibited delayed seed germination, growth retardation at the seedling stage, and delayed leaf senescence. RNA interference (RNAi) knocked-down plants (OsTZF1-RNAi) showed early seed germination, enhanced seedling growth, and early leaf senescence compared with controls. Ubi:OsTZF1-OX plants showed improved tolerance to high-salt and drought stresses and vice versa for OsTZF1-RNAi plants. Microarray analysis revealed that genes related to stress, reactive oxygen species homeostasis, and metal homeostasis were regulated in the Ubi:OsTZF1-OX plants. RNA-binding assays indicated that OsTZF1 binds to U-rich regions in the 3' untranslated region of messenger RNAs, suggesting that OsTZF1 might be associated with RNA metabolism of stress-responsive genes. OsTZF1 may serve as a useful biotechnological tool for the improvement of stress tolerance in various plants through the control of RNA metabolism of stress-responsive genes.
Translational control in brain pathologies: biological significance and therapeutic opportunities
Messenger RNA (mRNA) translation is the terminal step in protein synthesis, providing a crucial regulatory checkpoint for this process. Translational control allows specific cell types to respond to rapid changes in the microenvironment or to serve specific functions. For example, neurons use mRNA transport to achieve local protein synthesis at significant distances from the nucleus, the site of RNA transcription. Altered expression or functions of the various components of the translational machinery have been linked to several pathologies in the central nervous system. In this review, we provide a brief overview of the basic principles of mRNA translation, and discuss alterations of this process relevant to CNS disease conditions, with a focus on brain tumors and chronic neurological conditions. Finally, synthesizing this knowledge, we discuss the opportunities to exploit the biology of altered mRNA translation for novel therapies in brain disorders, as well as how studying these alterations can shed new light on disease mechanisms.
Trans-synaptic spreading of alpha-synuclein pathology through sensory afferents leads to sensory nerve degeneration and neuropathic pain
Pain is a common non-motor symptom of Parkinson’s disease (PD), with current limited knowledge of its pathophysiology. Here, we show that peripheral inoculation of mouse alpha-synuclein (α-Syn) pre-formed fibrils, in a transgenic mouse model of PD, elicited retrograde trans-synaptic spreading of α-Syn pathology (pSer129) across sensory neurons and dorsal nerve roots, reaching central pain processing regions, including the spinal dorsal horn and the projections of the anterolateral system in the central nervous system (CNS). Pathological peripheral to CNS propagation of α-Syn aggregates along interconnected neuronal populations within sensory afferents, was concomitant with impaired nociceptive response, reflected by mechanical allodynia, reduced nerve conduction velocities (sensory and motor) and degeneration of small- and medium-sized myelinated fibers. Our findings show a link between the transneuronal propagation of α-Syn pathology with sensory neuron dysfunction and neuropathic impairment, suggesting promising avenues of investigation into the mechanisms underlying pain in PD.
GLP-1 Receptor Agonists in Neurodegeneration: Neurovascular Unit in the Spotlight
Defects in brain energy metabolism and proteopathic stress are implicated in age-related degenerative neuronopathies, exemplified by Alzheimer’s disease (AD) and Parkinson’s disease (PD). As the currently available drug regimens largely aim to mitigate cognitive decline and/or motor symptoms, there is a dire need for mechanism-based therapies that can be used to improve neuronal function and potentially slow down the underlying disease processes. In this context, a new class of pharmacological agents that achieve improved glycaemic control via the glucagon-like peptide 1 (GLP-1) receptor has attracted significant attention as putative neuroprotective agents. The experimental evidence supporting their potential therapeutic value, mainly derived from cellular and animal models of AD and PD, has been discussed in several research reports and review opinions recently. In this review article, we discuss the pathological relevance of derangements in the neurovascular unit and the significance of neuron–glia metabolic coupling in AD and PD. With this context, we also discuss some unresolved questions with regard to the potential benefits of GLP-1 agonists on the neurovascular unit (NVU), and provide examples of novel experimental paradigms that could be useful in improving our understanding regarding the neuroprotective mode of action associated with these agents.
A beginner’s guide into curated analyses of open access datasets for biomarker discovery in neurodegeneration
The discovery of surrogate biomarkers reflecting neuronal dysfunction in neurodegenerative diseases (NDDs) remains an active area of research. To boost these efforts, we demonstrate the utility of publicly available datasets for probing the pathogenic relevance of candidate markers in NDDs. As a starting point, we introduce the readers to several open access resources, which contain gene expression profiles and proteomics datasets from patient studies in common NDDs, including proteomics analyses of cerebrospinal fluid (CSF). Then, we illustrate the method for curated gene expression analyses across select brain regions from four cohorts of Parkinson disease patients (and from one study in common NDDs), probing glutathione biogenesis, calcium signaling and autophagy. These data are complemented by findings of select markers in CSF-based studies in NDDs. Additionally, we enclose several annotated microarray studies, and summarize reports on CSF proteomics across the NDDs, which the readers can utilize for translational purposes. We anticipate that this “beginner’s guide” will benefit the research community in NDDs, and would serve as a useful educational tool.
Expression of the CCCH‐tandem zinc finger protein gene OsTZF5 under a stress‐inducible promoter mitigates the effect of drought stress on rice grain yield under field conditions
Summary Increasing drought resistance without sacrificing grain yield remains an ongoing challenge in crop improvement. In this study, we report that Oryza sativa CCCH‐tandem zinc finger protein 5 (OsTZF5) can confer drought resistance and increase grain yield in transgenic rice plants. Expression of OsTZF5 was induced by abscisic acid, dehydration and cold stress. Upon stress, OsTZF5‐GFP localized to the cytoplasm and cytoplasmic foci. Transgenic rice plants overexpressing OsTZF5 under the constitutive maize ubiquitin promoter exhibited improved survival under drought but also growth retardation. By introducing OsTZF5 behind the stress‐responsive OsNAC6 promoter in two commercial upland cultivars, Curinga and NERICA4, we obtained transgenic plants that showed no growth retardation. Moreover, these plants exhibited significantly increased grain yield compared to non‐transgenic cultivars in different confined field drought environments. Physiological analysis indicated that OsTZF5 promoted both drought tolerance and drought avoidance. Collectively, our results provide strong evidence that OsTZF5 is a useful biotechnological tool to minimize yield losses in rice grown under drought conditions.
Differences in Vegetative and Generative Characters of M2 Generation of Mutant Rice Compared to Wild Types and Commercial Cultivars
This study aims to obtain information on the differences in vegetative and generative characters of M2 generation rice mutants compared to wild types (MSP13 line) and commercial cultivars (IR64 and Ciherang). Gamma ray radiation treatment at 200 Gy was carried out on MSP13 line rice seeds in the M0 generation. The observation variables included plant height, number of productive tillers, age at harvest, weight of well-laden grains, and weight of 100 grains. The data obtained were analyzed by t test and cluster analysis. The results of t test showed that there are three M2 generation of mutant rice plants that have shorter plant sizes (dwarf), potential number of productive tillers, early harvest period and yield, compared to the wild type (MSP13 line), Ciherang and IR64 cultivars. Cluster analysis based on vegetative, generative and yield characters, obtained groups consisting of 9 and 66 rice mutant individuals with 21.87 % and 21.11 % similarity respectively compared to other rice mutant groups as well as wild type, Ciherang and IR64 varieties.
Introduction of Arabidopsis’s heat shock factor HsfA1d mitigates adverse effects of heat stress on potato (Solanum tuberosum L.) plant
Thermal stress induces a wide array of morphological and physiological changes in potato affecting its development and economic yield. Response to thermal stress in plants is mostly regulated by heat shock factors (hsfs). The current study aimed at improving heat tolerance by transforming potato plant with heat shock factor, HsfA1d, using Agrobacterium. Gateway cloning strategy was adopted for isolation of HsfA1d from Arabidopsis thaliana and cloning into plant expression vector. The target gene was introduced into potato by infecting internodal explants with Agrobacterium strain GV3101 carrying pGWB402O-HsfA1d construct. Upon exposure to heat stress, the wild-type plants turned yellowish, whereas no phenotypic effect on transgenic plants was observed. Expression of HsfA1d in transgenic plants was increased by 5.8-fold under thermal stress compared to room temperature. Transgenic plants exhibited 6-fold increase in the expression of downstream HSP70 under thermal stress compared to wild-type plants. Both chlorophyll a and b were significantly decreased in wild-type plants while no such decrease was recorded in transgenic plants under thermal stress. Heat stress was found to have no significant effect on carotenoid pigments of both wild-type and transgenic plants. Significantly lower electrolyte leakage from transgenic plants was witnessed compared to wild type upon exposure to thermal stress. Transgenic plants accumulated significantly higher proline content compared to wild-type plants under heat stress. It is concluded that HsfA1d plays a vital role in plant thermotolerance and hence can be effectively used to enhance the resistance of crop plants against heat stress.
α-Synuclein pathology in Parkinson disease activates homeostatic NRF2 anti-oxidant response
Circumstantial evidence points to a pathological role of alpha-synuclein (aSyn; gene symbol SNCA ), conferred by aSyn misfolding and aggregation, in Parkinson disease (PD) and related synucleinopathies. Several findings in experimental models implicate perturbations in the tissue homeostatic mechanisms triggered by pathological aSyn accumulation, including impaired redox homeostasis, as significant contributors in the pathogenesis of PD. The nuclear factor erythroid 2-related factor (NRF2/Nrf2) is recognized as ‘the master regulator of cellular anti-oxidant response’, both under physiological as well as in pathological conditions. Using immunohistochemical analyses, we show a robust nuclear NRF2 accumulation in post-mortem PD midbrain, detected by NRF2 phosphorylation on the serine residue 40 (nuclear active p-NRF2, S40). Curated gene expression analyses of four independent publicly available microarray datasets revealed considerable alterations in NRF2-responsive genes in the disease affected regions in PD, including substantia nigra, dorsal motor nucleus of vagus, locus coeruleus and globus pallidus. To further examine the putative role of pathological aSyn accumulation on nuclear NRF2 response, we employed a transgenic mouse model of synucleionopathy (M83 line, expressing the mutant human A53T aSyn), which manifests widespread aSyn pathology (phosphorylated aSyn; S129) in the nervous system following intramuscular inoculation of exogenous fibrillar aSyn. We observed strong immunodetection of nuclear NRF2 in neuronal populations harboring p-aSyn (S129), and found an aberrant anti-oxidant and inflammatory gene response in the affected neuraxis. Taken together, our data support the notion that pathological aSyn accumulation impairs the redox homeostasis in nervous system, and boosting neuronal anti-oxidant response is potentially a promising approach to mitigate neurodegeneration in PD and related diseases.