Abnormal expression of stathmin 1 in brain tissue of patients with intractable temporal lobe epilepsy and a rat model
ABSTRACT Microtubule dynamics have been shown to contribute to neurite outgrowth, branching, and guidance. Stathmin 1 is a potent microtubule-destabilizing factor that is involved in the regulation of microtubule dynamics and plays an essential role in neurite elongation and synaptic plasticity. Here, we investigate the expression of stathmin 1 in the brain tissues of patients with intractable temporal lobe epilepsy (TLE) and experimental animals using immunohistochemistry, immunofluorescence and western blotting. We obtained 32 temporal neocortex tissue samples from patients with intractable TLE and 12 histologically normal temporal lobe tissues as controls. In addition, 48 Sprague Dawley rats were randomly divided into six groups, including one control group and five groups with epilepsy induced by lithium chloride-pilocarpine. Hippocampal and temporal lobe tissues were obtained from control and epileptic rats on Days 1, 7, 14, 30, and 60 after kindling. Stathmin 1 was mainly expressed in the neuronal membrane and cytoplasm in the human controls, and its expression levels were significantly higher in patients with intractable TLE. Moreover, stathmin 1 was also expressed in the neurons of both the control and the experimental rats. Stathmin 1 expression was decreased in the experimental animals from 1 to 14 days postseizure and then significantly increased at Days 30 and 60 compared with the control group. Many protruding neuronal processes were observed in the TLE patients and in the chronic stage epileptic rats. These data suggest that stathmin 1 may participate in the abnormal network reorganization of synapses and contribute to the pathogenesis of TLE.
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ABSTRACT: Homocysteine (Hcy), a product of methionine metabolism, is elevated by the consumption of a high-methionine diet that can cause fatty liver disease. Paraoxonase 1 (Pon1), a hydrolase expressed mainly in the liver and carried in the circulation on high-density lipoprotein, participates in Hcy metabolism. Low Pon1 activity is linked to fatty liver disease. We hypothesize that hyperhomocysteinemia and low Pon1 induce changes in gene expression that could impair liver homeostasis. To test this hypothesis, we analyzed the liver proteome of Pon1(-/-) and Pon1(+/+) mice fed a high methionine diet (1% methionine in the drinking water) for 8 weeks using 2D IEF/SDS-PAGE gel electrophoresis and MALDI-TOF mass spectrometry. We identified seven liver proteins whose expression was significantly altered in Pon1(-/-) mice. In animals fed with a control diet, the expression of three liver proteins involved in lipoprotein metabolism (ApoE), iron metabolism (Ftl), and regulation of nitric oxide generation (Ddah1) was up-regulated by the Pon1(-/-) genotype. In mice fed with a high-methionine diet, expression of four liver proteins was up-regulated and of three proteins was down-regulated by the Pon1(-/-) genotype. The up-regulated proteins are involved in lipoprotein metabolism (ApoE), energy metabolism (Atp5h), oxidative stress response (Prdx2), and nitric oxide regulation (Ddah1). The down-regulated proteins are involved in energy metabolism (Gamt), iron metabolism (Ftl), and catechol metabolism (Comt). Expression of one protein (Ftl) was up-regulated both by the Pon1(-/-) genotype and a high-methionine diet. Our findings suggest that Pon1 interacts with diverse cellular processes (from lipoprotein metabolism, nitric oxide regulation, and energy metabolism to iron transport and antioxidant defenses) that are essential for normal liver homeostasis and modulation of these interactions by a high-methionine diet may contribute to fatty liver disease.Acta biochimica Polonica 10/2014; 61(4).
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ABSTRACT: Homocysteine (Hcy) is a risk factor for Alzheimer's disease (AD). Paraoxonase 1 (Pon1) participates in Hcy metabolism and is also linked to AD. The inactivation of the Pon1 gene in mice causes the accumulation of Hcy-thiolactone in the brain and increases the susceptibility to Hcy-thiolactone-induced seizures. To gain insight into the brain-related Pon1 function, we used two-dimensional IEF/SDS-PAGE gel electrophoresis and MALDI-TOF/TOF mass spectrometry to study brain proteomes of Pon1-/- and Pon1+/+ mice fed with a hyperhomocysteinemic high-methionine (Met) or a control diet. We found that: 1) proteins involved in brain-specific function (Nrgn), antioxidant defenses (Sod1, DJ-1), and cytoskeleton assembly (Tbcb, CapZa2) were differentially expressed in brains of Pon1-null mice; 2) proteins involved in brain-specific function (Ncald, Nrgn, Stmn1), antioxidant defenses (Prdx2, DJ-1), energy metabolism (Ak1), cell cycle (GDI1, Ran), cytoskeleton assembly (Tbcb), and unknown function (Hdhd2) showed differential expression in brains of Pon1-null fed with a hyperhomocysteinemic high-Met diet; 3) most proteins regulated by the Pon1-/- genotype were also regulated by the high-Met diet; 4) the proteins differentially expressed in Pon1-null mouse brains play important roles in neural development, learning, plasticity, and aging and are linked to neurodegenerative diseases, including AD. Taken together, our findings suggest that Pon1 interacts with diverse cellular processes from energy metabolism and anti-oxidative defenses to cell cycle, cytoskeleton dynamics, and synaptic plasticity essential for normal brain homeostasis and that these interactions are modulated by hyperhomocysteinemia and account for the involvement of Hcy and Pon1 in AD.Journal of Alzheimer's disease: JAD 05/2014; 42(1). DOI:10.3233/JAD-132714
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ABSTRACT: Axonal transport, a form of long-distance, bi-directional intracellular transport that occurs between the cell body and synaptic terminal, is critical in maintaining the function and viability of neurons. We have identified a requirement for the stathmin (stai) gene in the maintenance of axonal microtubules and regulation of axonal transport in Drosophila. The stai gene encodes a cytosolic phosphoprotein that regulates microtubule dynamics by partitioning tubulin dimers between pools of soluble tubulin and polymerized microtubules, and by directly binding to microtubules and promoting depolymerization. Analysis of stai function in Drosophila, which has a single stai gene, circumvents potential complications with studies performed in vertebrate systems in which mutant phenotypes may be compensated by genetic redundancy of other members of the stai gene family. This has allowed us to identify an essential function for stai in the maintenance of the integrity of axonal microtubules. In addition to the severe disruption in the abundance and architecture of microtubules in the axons of stai mutant Drosophila, we also observe additional neurological phenotypes associated with loss of stai function including a posterior paralysis and tail-flip phenotype in third instar larvae, aberrant accumulation of transported membranous organelles in stai deficient axons, a progressive bang-sensitive response to mechanical stimulation reminiscent of the class of Drosophila mutants used to model human epileptic seizures, and a reduced adult lifespan. Reductions in the levels of Kinesin-1, the primary anterograde motor in axonal transport, enhance these phenotypes. Collectively, our results indicate that stai has an important role in neuronal function, likely through the maintenance of microtubule integrity in the axons of nerves of the peripheral nervous system necessary to support and sustain long-distance axonal transport.PLoS ONE 06/2013; 8(6):e68324. DOI:10.1371/journal.pone.0068324