Publications by authors named "Nicholas Karagas"

Alzheimer disease (AD), the most common dementing syndrome in the United States, is currently established by the presence of amyloid-β and tau protein biomarkers in the setting of clinical cognitive impairment. These straightforward diagnostic parameters belie an immense complexity of genetic architecture underlying risk and presentation in AD. In this review, we provide a focused overview of the current state of AD genetics.

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  • - Mutations in the VAPB gene, linked to familial ALS, induce changes in the structure of motor neuron connections, leading to larger but fewer presynaptic boutons at the neuromuscular junction (NMJ).
  • - The morphological changes are tied to reduced microtubule stability due to hyperactivation of CaMKII caused by elevated calcium levels, which result from impaired calcium extrusion in neurons due to insufficient energy production.
  • - The study highlights a potential bioenergetic dysfunction in ALS-related motor neurons, where disrupted mitochondrial ATP production leads to an inability to meet the energy demands of neuronal activity, contributing to synaptic defects.
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  • - Large-scale use of insecticides is harming beneficial insect populations, prompting the search for safer alternatives like spinosad, which is thought to be less toxic to beneficial insects.
  • - Research reveals that low doses of spinosad interfere with a specific receptor (nAChRα6) in the nervous system, causing issues such as enlarged lysosomes and mitochondrial stress, which contribute to harmful effects on insects.
  • - Chronic exposure to low doses of spinosad leads to severe neurodegeneration and blindness in female insects, highlighting the need for deeper research into its negative effects on beneficial species.
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Olfactory dysfunction is a common symptom in patients with neurodegenerative disorders, including Huntington's disease (HD). Understanding its pathophysiology is important in establishing a preventive and therapeutic plan. In this literature review, we cover the physiology of olfaction, its role in neurodegeneration, and its characteristics in patients with HD.

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Mitochondrial ATP production is a well-known regulator of neuronal excitability. The reciprocal influence of plasma-membrane potential on ATP production, however, remains poorly understood. Here, we describe a mechanism by which depolarized neurons elevate the somatic ATP/ADP ratio in glutamatergic neurons.

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  • Declining insect populations are raising global concerns due to their crucial roles in ecosystems and food production, with insecticide use being a major contributing factor.
  • This study focuses on the impacts of the insecticide imidacloprid, revealing that it causes oxidative stress and alters neuronal functioning at low doses, leading to various physiological and behavioral changes in insects.
  • Chronic exposure to imidacloprid results in mitochondrial dysfunction and damage to essential cells, suggesting that oxidative stress plays a significant role in the adverse effects of insecticides, which could have broader consequences for insect resilience amidst environmental pressures.
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Huntington's disease (HD) is a heritable and fatal neurodegenerative disease characterized by a triad of motor, cognitive and neuropsychiatric symptoms. A common and particularly detrimental neuropsychiatric alteration in HD gene carriers is irritability, which frequently manifests as abrupt and unpredictable outbursts of anger. This symptom increases the burden of HD in multiple ways, such as jeopardizing employment and straining familial or caregiver support.

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By influencing Ca homeostasis in spatially and architecturally distinct neuronal compartments, the endoplasmic reticulum (ER) illustrates the notion that form and function are intimately related. The contribution of ER to neuronal Ca homeostasis is attributed to the organelle being the largest reservoir of intracellular Ca and having a high density of Ca channels and transporters. As such, ER Ca has incontrovertible roles in the regulation of axodendritic growth and morphology, synaptic vesicle release, and neural activity dependent gene expression, synaptic plasticity, and mitochondrial bioenergetics.

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By serving as intermediaries between cellular metabolism and the bioenergetic demands of proliferation, endolysosomes allow cancer cells to thrive under normally detrimental conditions. Here, we show that an endolysosomal TRP channel, TRPML1, is necessary for the proliferation of cancer cells that bear activating mutations in Expression of , which encodes TRPML1, is significantly elevated in -positive tumors and inversely correlated with patient prognosis. Concordantly, knockdown or TRPML1 inhibition selectively reduces the proliferation of cancer cells that express oncogenic, but not wild-type, Mechanistically, TRPML1 maintains oncogenic HRAS in signaling-competent nanoclusters at the plasma membrane by mediating cholesterol de-esterification and transport.

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Rieske and Rieske-type proteins are electron transport proteins involved in key biological processes such as respiration, photosynthesis, and detoxification. They have a [2Fe-2S] cluster ligated by two cysteines and two histidines. A series of mutations, L135E, L135R, L135A, and Y158F, of the Rieske protein from Thermus thermophilus has been produced which probe the effects of the neighboring residues, in the second sphere, on the dynamics of cluster reduction and the reactivity of the ligating histidines.

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