Deficits in motor and cognitive functions in an adult mouse model of hypoxia-ischemia induced stroke.

Ischemic strokes cause devastating brain damage and functional deficits with few treatments available. Previous studies have shown that the ischemia-hypoxia rapidly induces clinically similar thrombosis and neuronal loss, but any resulting behavioral changes are largely unknown. The goal of this study was to evaluate motor and cognitive deficits in adult HI mice.

Chemical Conversion of Human Fetal Astrocytes into Neurons through Modulation of Multiple Signaling Pathways.

We have previously developed a cocktail of nine small molecules to convert human fetal astrocytes into neurons, but a nine-molecule recipe is difficult for clinical applications. Here, we identify a chemical formula with only three to four small molecules for astrocyte-to-neuron conversion. We demonstrate that modulation of three to four signaling pathways among Notch, glycogen synthase kinase 3, transforming growth factor β, and bone morphogenetic protein pathways is sufficient to change an astrocyte into a neuron.

Potent block of potassium channels by MEK inhibitor U0126 in primary cultures and brain slices.

U0126 (1,4-diamino-2,3-dicyano-1,4-bis (2-aminophenylthio) butadiene), a widely used mitogen-activated protein kinase kinase (MEK) inhibitor, was found to accelerate voltage-gated K channel (K) inactivation in heterologous cells expressing several types of K. The goal of this study was to examine whether U0126 at a concentration thought to specifically inhibit MEK signaling also inhibits K in native neurons of primary cultures or brain slices. U0126 caused a dose-dependent inhibition of both the transient (I) and sustained (I) components of K currents in hippocampal neurons.

Gad67 haploinsufficiency reduces amyloid pathology and rescues olfactory memory deficits in a mouse model of Alzheimer's disease.

Background: Alzheimer's disease (AD) is the most common age-related neurodegenerative disorder, affecting millions of people worldwide. Although dysfunction of multiple neurotransmitter systems including cholinergic, glutamatergic and GABAergic systems has been associated with AD progression the underlying mechanisms remain elusive. We and others have recently found that GABA content is elevated in AD brains and linked to cognitive deficits in AD mouse models.

Small Molecules Efficiently Reprogram Human Astroglial Cells into Functional Neurons.

We have recently demonstrated that reactive glial cells can be directly reprogrammed into functional neurons by a single neural transcription factor, NeuroD1. Here we report that a combination of small molecules can also reprogram human astrocytes in culture into fully functional neurons. We demonstrate that sequential exposure of human astrocytes to a cocktail of nine small molecules that inhibit glial but activate neuronal signaling pathways can successfully reprogram astrocytes into neurons in 8-10 days.

Distribution of RGS9-2 in neurons of the mouse striatum.

Regulators of G protein signaling (RGS) proteins negatively modulate G protein-coupled receptor (GPCR) signaling activity by accelerating G protein hydrolysis of GTP, hastening pathway shutoff. A wealth of data from cell culture experiments using exogenously expressed proteins indicates that RGS9 and other RGS proteins have the potential to down-regulate a significant number of pathways. We have used an array of biochemical and tissue staining techniques to examine the subcellular localization and membrane binding characteristics of endogenous RGS9-2 and known binding partners in rodent striatum and tissue homogenates.

Tacrolimus reduces nitric oxide synthase function by binding to FKBP rather than by its calcineurin effect.

Hypertension develops in many patients receiving the immunosuppressive drug tacrolimus (FK506). One possible mechanism for hypertension is a reduction in vasodilatory nitric oxide. We found that tacrolimus and a calcineurin autoinhibitory peptide significantly decreased vascular calcineurin activity; however, only tacrolimus altered intracellular calcium release in mouse aortic endothelial cells.

Postsynaptic potentials and axonal projections of tegmental neurons responding to electrical stimulation of the toad striatum.

The amphibian telencephalic striatum as a major component of the basal ganglia receives multisensory information and projects to the tegmentum and other structures. However, how striatal neurons modulate tegmental activity remains unknown. Here, we show by using intracellular recording and staining in toads that electrical stimulation of the ipsilateral striatum evoked an inhibitory postsynaptic potential (IPSP) in presumably binocular tegmental neurons.

Removal of FKBP12/12.6 from endothelial ryanodine receptors leads to an intracellular calcium leak and endothelial dysfunction.

Objectives: FK506 Binding Protein 12 and its related isoform 12.6 (FKBP12/12.6) stabilize a closed state of intracellular Ca2+ release channels (ryanodine receptors [RyRs]), and in myocytes removal of FKBP12/12.

FK506 binding protein 12/12.6 depletion increases endothelial nitric oxide synthase threonine 495 phosphorylation and blood pressure.

Chronic treatment with the immunosuppressive drug rapamycin leads to hypertension; however, the mechanisms are unknown. Rapamycin binds FK506 binding protein 12 and its related isoform 12.6 (FKBP12/12.

Hippocampal long-term potentiation, memory, and longevity in mice that overexpress mitochondrial superoxide dismutase.

Superoxide has been shown to be critically involved in several pathological manifestations of aging animals. In contrast, superoxide also can act as a signaling molecule to modulate signal transduction cascades required for hippocampal synaptic plasticity. Mitochondrial superoxide dismutase (SOD-2 or Mn-SOD) is a key antioxidant enzyme that scavenges superoxide.

Manipulating Kv4.2 identifies a specific component of hippocampal pyramidal neuron A-current that depends upon Kv4.2 expression.

The somatodendritic A-current, I(SA), in hippocampal CA1 pyramidal neurons regulates the processing of synaptic inputs and the amplitude of back propagating action potentials into the dendritic tree, as well as the action potential firing properties at the soma. In this study, we have used RNA interference and over-expression to show that expression of the Kv4.2 gene specifically regulates the I(SA) component of A-current in these neurons.

A novel method of loading samples onto mini-gels for SDS-PAGE: increased sensitivity and Western blots using sub-microgram quantities of protein.

Commercially available mini-gels for sodium dodecyl sulphate (SDS)-PAGE and Western blotting are limited both by the number of lanes that can be loaded per gel and the minimum amount of protein per lane that must be loaded. Here we describe a method for loading protein samples onto existing commercially available mini-gels that allows loading of 50 or more lanes per gel. The enhanced sensitivity of the method allows Western blotting with sub-microgram quantities of protein.

Regulation of dendritic morphogenesis by Ras-PI3K-Akt-mTOR and Ras-MAPK signaling pathways.

Dendritic arborization and spine formation are critical for the functioning of neurons. Although many proteins have been identified recently as regulators of dendritic morphogenesis, the intracellular signaling pathways that control these processes are not well understood. Here we report that the Ras-phosphatidylinositol 3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) signaling pathway plays pivotal roles in the regulation of many aspects of dendrite formation.

The Rho-specific GEF Lfc interacts with neurabin and spinophilin to regulate dendritic spine morphology.

Neurabin and spinophilin are homologous protein phosphatase 1 and actin binding proteins that regulate dendritic spine function. A yeast two-hybrid analysis using the coiled-coil domain of neurabin revealed an interaction with Lfc, a Rho GEF. Lfc was highly expressed in brain, where it interacted with either neurabin or spinophilin.

Synaptic localization of a functional NADPH oxidase in the mouse hippocampus.

Superoxide has been shown to be critical for hippocampal long-term potentiation (LTP) and hippocampus-dependent memory function. A possible source for the generation of superoxide during these processes is NADPH oxidase. The active oxidase consists of two membrane proteins, gp91phox and p22phox, and four cytosolic proteins, p40phox, p47phox, p67phox, and Rac.

Calcium-calmodulin-dependent kinase II modulates Kv4.2 channel expression and upregulates neuronal A-type potassium currents.

Calcium-calmodulin-dependent kinase II (CaMKII) has a long history of involvement in synaptic plasticity, yet little focus has been given to potassium channels as CaMKII targets despite their importance in repolarizing EPSPs and action potentials and regulating neuronal membrane excitability. We now show that Kv4.2 acts as a substrate for CaMKII in vitro and have identified CaMKII phosphorylation sites as Ser438 and Ser459.

Time-lapse in vivo imaging of the morphological development of Xenopus optic tectal interneurons.

Excitatory and inhibitory interneurons play a key role in the establishment of neuronal responses and circuit properties in the brain. Despite their importance in brain function, the structural development of interneurons has not been well studied. We used in vivo time-lapse imaging in intact anesthetized Xenopus tadpoles to determine the morphological events underlying the development of interneuron dendritic arbor structure.

Stanniocalcin-1 is a naturally occurring L-channel inhibitor in cardiomyocytes: relevance to human heart failure.

Cardiomyocytes of the failing heart undergo profound phenotypic and structural changes that are accompanied by variations in the genetic program and profile of calcium homeostatic proteins. The underlying mechanisms for these changes remain unclear. Because the mammalian counterpart of the fish calcium-regulating hormone stanniocalcin-1 (STC1) is expressed in the heart, we reasoned that STC1 might play a role in the adaptive-maladaptive processes that lead to the heart failure phenotype.