A selective inhibitor of the sperm-specific potassium channel SLO3 impairs human sperm function.

To fertilize an oocyte, the membrane potential of both mouse and human sperm must hyperpolarize (become more negative inside). Determining the molecular mechanisms underlying this hyperpolarization is vital for developing new contraceptive methods and detecting causes of idiopathic male infertility. In mouse sperm, hyperpolarization is caused by activation of the sperm-specific potassium (K) channel SLO3 [C.

VU6036720: The First Potent and Selective In Vitro Inhibitor of Heteromeric Kir4.1/5.1 Inward Rectifier Potassium Channels.

Heteromeric Kir4.1/Kir5.1 (/) inward rectifier potassium (Kir) channels play key roles in the brain and kidney, but pharmacological tools for probing their physiology and therapeutic potential have not been developed.

Defective AMPA-mediated synaptic transmission and morphology in human neurons with hemizygous SHANK3 deletion engrafted in mouse prefrontal cortex.

Genetic abnormalities in synaptic proteins are common in individuals with autism; however, our understanding of the cellular and molecular mechanisms disrupted by these abnormalities is limited. SHANK3 is a postsynaptic scaffolding protein of excitatory synapses that has been found mutated or deleted in most patients with 22q13 deletion syndrome and about 2% of individuals with idiopathic autism and intellectual disability. Here, we generated CRISPR/Cas9-engineered human pluripotent stem cells (PSCs) with complete hemizygous SHANK3 deletion (SHANK3), which is the most common genetic abnormality in patients, and investigated the synaptic and morphological properties of SHANK3-deficient PSC-derived cortical neurons engrafted in the mouse prefrontal cortex.

Isoforms Differentially Regulate Gene Expression, Synaptic Transmission, and Memory in the Mammalian Brain.

The dynamic regulation of DNA methylation in postmitotic neurons is necessary for memory formation and other adaptive behaviors. Ten-eleven translocation 1 (TET1) plays a part in these processes by oxidizing 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), thereby initiating active DNA demethylation. However, attempts to pinpoint its exact role in the nervous system have been hindered by contradictory findings, perhaps due in part, to a recent discovery that two isoforms of the gene are differentially expressed from early development into adulthood.

Leptin suppresses development of GLP-1 inputs to the paraventricular nucleus of the hypothalamus.

The nucleus of the solitary tract (NTS) is critical for the central integration of signals from visceral organs and contains preproglucagon (PPG) neurons, which express leptin receptors in the mouse and send direct projections to the paraventricular nucleus of the hypothalamus (PVH). Here, we visualized projections of PPG neurons in leptin-deficient mice and found that projections from PPG neurons are elevated compared with controls, and PPG projections were normalized by targeted rescue of leptin receptors in mice, which lack functional neuronal leptin receptors. Moreover, and mice displayed increased levels of neuronal activation in the PVH following vagal stimulation, and whole-cell patch recordings of GLP-1 receptor-expressing PVH neurons revealed enhanced excitatory neurotransmission, suggesting that leptin acts cell autonomously to suppress representation of excitatory afferents from PPG neurons, thereby diminishing the impact of visceral sensory information on GLP-1 receptor-expressing neurons in the PVH.

VU0606170, a Selective Slack Channels Inhibitor, Decreases Calcium Oscillations in Cultured Cortical Neurons.

Malignant migrating partial seizures of infancy is a rare, devastating form of epilepsy most commonly associated with gain-of-function mutations in the potassium channel, Slack. Not only is this condition almost completely pharmacoresistant, there are not even selective drug-like tools available to evaluate whether inhibition of these overactivated, mutant Slack channels may represent a viable path forward toward new antiepileptic therapies. Therefore, we used a high-throughput thallium flux assay to screen a drug-like, 100 000-compound library in search of inhibitors of both wild-type and a disease-associated mutant Slack channel.

Reciprocal modulation between amyloid precursor protein and synaptic membrane cholesterol revealed by live cell imaging.

The amyloid precursor protein (APP) has been extensively studied because of its association with Alzheimer's disease (AD). However, APP distribution across different subcellular membrane compartments and its function in neurons remains unclear. We generated an APP fusion protein with a pH-sensitive green fluorescent protein at its ectodomain and a pH-insensitive blue fluorescent protein at its cytosolic domain and used it to measure APP's distribution, subcellular trafficking, and cleavage in live neurons.

Fluorescent Measurement of Synaptic Activity Using FM Dyes in Dissociated Hippocampal Cultured Neurons.

Release and recycling of synaptic vesicles are essential for neurotransmission and synaptic plasticity. To gain mechanistic understanding of these processes, direct measurements of vesicle release and retrieval is indispensable. Styryl dyes like FM1-43 and FM4-64 have been widely used for this purpose and their loading and unloading are reliable measurements for synaptic vesicle release and retrieval in cultured neurons.

Membrane cholesterol mediates the cellular effects of monolayer graphene substrates.

Graphene possesses extraordinary properties that promise great potential in biomedicine. However, fully leveraging these properties requires close contact with the cell surface, raising the concern of unexpected biological consequences. Computational models have demonstrated that graphene preferentially interacts with cholesterol, a multifunctional lipid unique to eukaryotic membranes.

Ammonium chloride alters neuronal excitability and synaptic vesicle release.

Genetically encoded pH-sensors are widely used in studying cell membrane trafficking and membrane protein turnover because they render exo-/endocytosis-associated pH changes to fluorescent signals. For imaging and analysis purposes, high concentration ammonium chloride is routinely used to alkalize intracellular membrane compartments under the assumption that it does not cause long-term effects on cellular processes being studied like neurotransmission. However, pathological studies about hyperammonemia have shown that ammonium is toxic to brain cells especially astrocytes and neurons.

PHYSIOLOGY. Regulation of breathing by CO₂ requires the proton-activated receptor GPR4 in retrotrapezoid nucleus neurons.

Blood gas and tissue pH regulation depend on the ability of the brain to sense CO2 and/or H(+) and alter breathing appropriately, a homeostatic process called central respiratory chemosensitivity. We show that selective expression of the proton-activated receptor GPR4 in chemosensory neurons of the mouse retrotrapezoid nucleus (RTN) is required for CO2-stimulated breathing. Genetic deletion of GPR4 disrupted acidosis-dependent activation of RTN neurons, increased apnea frequency, and blunted ventilatory responses to CO2.

A Stem Cell-Derived Platform for Studying Single Synaptic Vesicles in Dopaminergic Synapses.

The exocytotic release of dopamine is one of the most characteristic but also one of the least appreciated processes in dopaminergic neurotransmission. Fluorescence imaging has yielded rich information about the properties of synaptic vesicles and the release of neurotransmitters in excitatory and inhibitory neurons. In contrast, imaging-based studies for in-depth understanding of synaptic vesicle behavior in dopamine neurons are lagging largely because of a lack of suitable preparations.

D-chiro-inositol glycan stimulates insulin secretion in pancreatic β cells.

Insulin has been shown to act on pancreatic β cells to regulate its own secretion. Currently the mechanism underlying this effect is unclear. INS-2, a novel inositol glycan pseudo-disaccharide containing D-chiro-inositol and galactosamine, has been shown to function as an insulin mimetic and a putative insulin mediator.

Effect of Competitive Surface Functionalization on Dual-Modality Fluorescence and Magnetic Resonance Imaging of Single-Walled Carbon Nanotubes.

It is well-known that ionic surfactant coated single-walled carbon nanotubes (SWNTs) possess higher near-infrared fluorescence (NIRF) quantum yield than nonionic polymer functionalized SWNTs. However, the influence of surface functionalization on the magnetic properties of SWNTs for -weighted magnetic resonance imaging (MRI) has not been reported. Here, we demonstrate that SWNTs functionalized by nonionic polymers display superior relaxivity for MRI as compared to those coated by ionic surfactants.

Molecular and biophysical basis of glutamate and trace metal modulation of voltage-gated Ca(v)2.3 calcium channels.

Here, we describe a new mechanism by which glutamate (Glu) and trace metals reciprocally modulate activity of the Ca(v)2.3 channel by profoundly shifting its voltage-dependent gating. We show that zinc and copper, at physiologically relevant concentrations, occupy an extracellular binding site on the surface of Ca(v)2.

Orexin A activates retrotrapezoid neurons in mice.

The retrotrapezoid nucleus (RTN), located at the ventral surface of the medulla oblongata, contains glutamatergic Phox2b-expressing interneurons that have central respiratory chemoreceptor properties. RTN also operates as a relay for hypothalamic pathways that regulate breathing, one of which probably originates from the orexinergic neurons (Dias et al., 2009.

Rapid developmental maturation of neocortical FS cell intrinsic excitability.

Fast-spiking (FS) cells are a prominent subtype of neocortical γ-aminobutyric acidergic interneurons that mediate feed-forward inhibition and the temporal sculpting of information transfer in neural circuits, maintain excitation/inhibition balance, and contribute to network oscillations. FS cell dysfunction may be involved in the pathogenesis of disorders such as epilepsy, autism, and schizophrenia. Mature FS cells exhibit coordinated molecular and cellular specializations that facilitate rapid responsiveness, including brief spikes and sustained high-frequency discharge.

Anesthetic activation of central respiratory chemoreceptor neurons involves inhibition of a THIK-1-like background K(+) current.

At surgical depths of anesthesia, inhalational anesthetics cause a loss of motor response to painful stimuli (i.e., immobilization) that is characterized by profound inhibition of spinal motor circuits.

Motoneuronal TASK channels contribute to immobilizing effects of inhalational general anesthetics.

General anesthetics cause sedation, hypnosis, and immobilization via CNS mechanisms that remain incompletely understood; contributions of particular anesthetic targets in specific neural pathways remain largely unexplored. Among potential molecular targets for mediating anesthetic actions, members of the TASK subgroup [TASK-1 (K2P3.1) and TASK-3 (K2P9.

Acid sensitivity and ultrastructure of the retrotrapezoid nucleus in Phox2b-EGFP transgenic mice.

The retrotrapezoid nucleus (RTN) contains noncholinergic noncatecholaminergic glutamatergic neurons that express the transcription factor Phox2b (chemically coded or "cc" RTN neurons). These cells regulate breathing and may be central chemoreceptors. Here we explore their ultrastructure and their acid sensitivity by using two novel BAC eGFP-Phox2b transgenic mice (B/G, GENSAT JX99) in which, respectively, 36% and 100% of the cc RTN neurons express the transgene in complete or partial anatomical isolation from other populations of eGFP neurons.

[Alterations in ATP-dependence of swelling-activated Cl- current associated with neuroendocrine differentiation of LNCaP human prostate cancer epithelial cells].

Increasing population of malignant, apoptosis resistant neuroendocrine (NE) cells due to differentiation of prostate epithelial/basal cells is a hallmark of advanced, androgen-independent prostate cancer, for which there is no successful therapy. Acquisition of apoptosis resistance involves alterations in the mechanisms of cell volume homeostasis, of which volume-regulate anion channels (VRAC) that carry swelling-activated Cl- current (I(Cl,swell)) represent one of the key determinants. Given that VRAC function is generally known to be ATP-dependent, here we investigated how such dependence may evolve during NE differentiation of LNCaP prostate cancer epithelial cells.

Alterations in the regulatory volume decrease (RVD) and swelling-activated Cl- current associated with neuroendocrine differentiation of prostate cancer epithelial cells.

Neuroendocrine (NE) differentiation of prostate epithelial/basal cells is a hallmark of advanced, androgen-independent prostate cancer, for which there is no successful therapy. Here we report for the first time on alterations in regulatory volume decrease (RVD) and its key determinant, swelling-activated Cl- current (I(Cl,swell)), associated with NE differentiation of androgen-dependent LNCaP prostate cancer epithelial cells. NE-differentiating regimens, namely, chronic cAMP elevation or androgen deprivation, resulted in generally augmented I(Cl,swell) and enhanced RVD.

[Effect of neuroendocrine cell differentiation of the human prostatic neoplasm cell line LNCaP on the characteristics of volume-sensitive chloride content].

By means of patch-clamp technique we examined changes in volume-regulated chloride current (ICl,swell) at neuroendocrine differentiation of androgen-dependent LNCaP prostate cancer cells. In those cells with neuroendocrine differentiation resulted from an increase in the intracellular cAMP, ICl,swell became much faster in response to applying external hypotonic solution and cell swelling. Changes in final rectification and voltage-dependent inactivation were not detected, as compared to the control cells.

[Effect of intracellular trypsin on characteristics of voltage-dependent inactivation of chloride currents in prostatic cancer cells].

By means of the patch-clamp technique we have studied the effects of intracellular applied trypsin, a known modulator of membrane channel function, on the properties of the Cl- current induced by hypotonicity-obliged cell swelling (ICl, swell) in human prostate cancer epithelial cells, LNCaP. Intracellular infusion of 1 mg/ml of trypsin into LNCaP cells via the patch pipette shortened the delay for the onset and the time of development of ICl, swell in response to hypotonicity as well as accelerated the rate of current diminution following the return to isotonic conditions. The maximal density of ICl, swell in the presence of intracellular trypsin was 2-fold higher while the current voltage-dependent inactivation at high depolarizing potentials was virtually eliminated.