The SNARE complex in neuronal and sensory cells

Abstract

Transmitter release at synapses ensures faithful chemical coding of information that is transmitted in the sub-second time frame. The brain, the central unit of information processing, depends upon fast communication for decision making. Neuronal and neurosensory cells are equipped with the molecular machinery that responds reliably, and with high fidelity, to external stimuli. However, neuronal cells differ markedly from neurosensory cells in their signal transmission at synapses. The main difference rests in how the synaptic complex is organized, with active zones in neuronal cells and ribbon synapses in sensory cells (such as photoreceptors and hair cells). In exocytosis/neurosecretion, SNAREs (soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptors) and associated proteins play a critical role in vesicle docking, priming, fusion and synchronization of neurotransmitter release. Recent studies suggest differences between neuronal and sensory cells with respect to the molecular components of their synaptic complexes. In this review, we will cover current findings on neuronal and sensory-cell SNARE proteins and their modulators. We will also briefly discuss recent investigations on how deficits in the expression of SNARE proteins in humans impair function in brain and sense organs.

Calcium Regulates Molecular Interactions of Otoferlin with Soluble NSF Attachment Protein Receptor (SNARE) Proteins Required for Hair Cell Exocytosis

“…Likewise, hair cell exocytosis has been demonstrated to be fast, synchronous, and calcium-dependent (5). However, whereas the basic machinery of vesicle fusion is similar in different fast synapses, the modulation of vesicle fusion in these synapses appears to differ (31).…”

Transducin translocation contributes to rod survival and enhances synaptic transmission from rods to rod bipolar cells

“…Specifically, Gβ 1 γ 1 and synaptotagmin have been shown to compete for binding to SNAP25, syntaxin1A, and the ternary SNARE complex in a Ca 2+ -dependent manner. The SNARE complexes in central and ribbon synapses are thought to comprise of homologous proteins (41). Thus, the light-induced decrease in intracellular Ca 2+ in the rod spherule might augment the inhibitory action of Gβ 1 γ 1 on the SNARE proteins and facilitate the reduction in glutamate release.…”

Can the ‘neuron theory’ be complemented by a universal mechanism for generic neuronal differentiation

“…They are also expressed in cell types other than neurons such as endocrine (for reviews, see Pang and Südhof 2010;Lang and Jahn 2008) and sensory receptor cells (for reviews, see Zanazzi and Matthews 2009;Ramakrishnan et al 2012). In addition to neuronal, sensory receptor, and endocrine cells, the in cell lineage-terms distant, mast cells also employ the SNARE complex for mediator release (Lorentz et al 2012).…”

“…These include synaptotagmin I, Vamp-2, Snap-25 or Rab3a. These proteins are also found in hair cell ribbon synapses in the inner ear where synaptotagmin I is developmentally downregulated in mice (for reviews, see Zanazzi and Matthews 2009;Ramakrishnan et al 2012). Different from neurons, complexin 1 and 2 are not detected in photoreceptors and hair cells while the protein ribeye appears unique to ribbon synapses.…”