A role for synapsin tetramerization in synaptic vesicle clustering.

Although synapsins have long been proposed to be key regulators of synaptic vesicle (SV) clustering, their mechanism of action has remained mysterious and somewhat controversial. Here, we review synapsins and their associations with each other and with SVs. We highlight the recent hypothesis that synapsin tetramerization is a mechanism for SV clustering.

Different mechanisms of synapsin-induced vesicle clustering at inhibitory and excitatory synapses.

Synapsins cluster synaptic vesicles (SVs) to provide a reserve pool (RP) of SVs that maintains synaptic transmission during sustained activity. However, it is unclear how synapsins cluster SVs. Here we show that either liquid-liquid phase separation (LLPS) or tetramerization-dependent cross-linking can cluster SVs, depending on whether a synapse is excitatory or inhibitory.

Author Correction: Structural basis for delta cell paracrine regulation in pancreatic islets.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Structural basis for delta cell paracrine regulation in pancreatic islets.

Little is known about the role of islet delta cells in regulating blood glucose homeostasis in vivo. Delta cells are important paracrine regulators of beta cell and alpha cell secretory activity, however the structural basis underlying this regulation has yet to be determined. Most delta cells are elongated and have a well-defined cell soma and a filopodia-like structure.

Src-mediated phosphorylation of βPix-b regulates dendritic spine morphogenesis.

PAK-interacting guanine nucleotide exchange factor (βPix; also known as Arhgef7) has been implicated in many actin-based cellular processes, including spine morphogenesis in neurons. However, the molecular mechanisms by which βPix controls spine morphology remain elusive. Previously, we have reported the expression of several alternative spliced βPix isoforms in the brain.

Molecular Mechanisms of Short-Term Plasticity: Role of Synapsin Phosphorylation in Augmentation and Potentiation of Spontaneous Glutamate Release.

We used genetic and pharmacological approaches to identify the signaling pathways involved in augmentation and potentiation, two forms of activity dependent, short-term synaptic plasticity that enhance neurotransmitter release. Trains of presynaptic action potentials produced a robust increase in the frequency of miniature excitatory postsynaptic currents (mEPSCs). Following the end of the stimulus, mEPSC frequency followed a bi-exponential decay back to basal levels.

Novel luciferase-opsin combinations for improved luminopsins.

Previous work has demonstrated that fusion of a luciferase to an opsin, to create a luminescent opsin or luminopsin, provides a genetically encoded means of manipulating neuronal activity via both chemogenetic and optogenetic approaches. Here we have expanded and refined the versatility of luminopsin tools by fusing an alternative luciferase variant with high light emission, Gaussia luciferase mutant GLucM23, to depolarizing and hyperpolarizing channelrhodopsins with increased light sensitivity. The combination of GLucM23 with Volvox channelrhodopsin-1 produced LMO4, while combining GLucM23 with the anion channelrhodopsin iChloC yielded iLMO4.

Synapsin Isoforms Regulating GABA Release from Hippocampal Interneurons.

Unlabelled: Although synapsins regulate GABA release, it is unclear which synapsin isoforms are involved. We identified the synapsin isoforms that regulate GABA release via rescue experiments in cultured hippocampal neurons from synapsin I, II, and III triple knock-out (TKO) mice. In situ hybridization indicated that five different synapsin isoforms are expressed in hippocampal interneurons.

Synapsin Isoforms and Synaptic Vesicle Trafficking.

Synapsins were the first presynaptic proteins identified and have served as the flagship of the presynaptic protein field. Here we review recent studies demonstrating that different members of the synapsin family play different roles at presynaptic terminals employing different types of synaptic vesicles. The structural underpinnings for these functions are just beginning to be understood and should provide a focus for future efforts.

The topographical guidance of neurons cultured on holographic photo-responsive polymer.

Neuronal cells to respond to submicron-scale groove structure. On the grooved structure of particular dimension, it has been reported that neuronal cells grew perpendicular to the groove direction. We used holographic photo-responsive polymer to form a submicron-scale surface relief grating structure.

Anti-HIV protease activity from rosa family plant extracts and rosamultin from Rosa rugosa.

To identify substances with anti-human immunodeficiency virus (HIV) activity from plant sources, 12 extracts of Rosa family plants were screened for their inhibitory effects against HIV-1 protease. Of the extracts tested, the strongest inhibitory effects were observed in the root of Rosa rugosa and the leaves of Prunus sargentii, at a concentration of 100 microg/mL. Rosamultin isolated from the root of R.