RIMs and RIM-binding proteins (RBPs) are evolutionary conserved multidomain proteins of presynaptic active zones that are known to recruit Ca2+ channels; in addition, RIMs perform well-recognized ...functions in tethering and priming synaptic vesicles for exocytosis. However, deletions of RIMs or RBPs in mice cause only partial impairments in various active zone functions and have no effect on active zone structure, as visualized by electron micrographs, suggesting that their contribution to active zone functions is limited. Here, we show in synapses of the calyx of Held in vivo and hippocampal neurons in culture that combined, but not individual, deletions of RIMs and RBPs eliminate tethering and priming of synaptic vesicles, deplete presynaptic Ca2+ channels, and ablate active zone complexes, as analyzed by electron microscopy of chemically fixed synapses. Thus, RBPs perform unexpectedly broad roles at the active zone that together with those of RIMs are essential for all active zone functions.
•RIM and RBP active zone proteins exhibit universal redundancy at synapses•Combined, but not individual, RIM and RBP deletion blocks synaptic vesicle priming•RIM/RBP-deficient synapses lack tethered vesicles and localized Ca2+ channels•Presynaptic combined RIM/RBP deletion impairs postsynaptic density organization
Acuna and colleagues show that combined, but not individual, deletions of the active zone proteins RIMs and RBPs severely impair all active zone functions and alter the trans-synaptic organization of postsynaptic receptors, suggesting unexpectedly broad, redundant functions for these proteins.
Available methods for differentiating human embryonic stem cells (ESCs) and induced pluripotent cells (iPSCs) into neurons are often cumbersome, slow, and variable. Alternatively, human fibroblasts ...can be directly converted into induced neuronal (iN) cells. However, with present techniques conversion is inefficient, synapse formation is limited, and only small amounts of neurons can be generated. Here, we show that human ESCs and iPSCs can be converted into functional iN cells with nearly 100% yield and purity in less than 2 weeks by forced expression of a single transcription factor. The resulting ES-iN or iPS-iN cells exhibit quantitatively reproducible properties independent of the cell line of origin, form mature pre- and postsynaptic specializations, and integrate into existing synaptic networks when transplanted into mouse brain. As illustrated by selected examples, our approach enables large-scale studies of human neurons for questions such as analyses of human diseases, examination of human-specific genes, and drug screening.
•Neurogenin-2 overexpression rapidly transforms ESCs and iPSCs into neurons•Neurogenin-2-induced human neurons form spontaneous excitatory synaptic networks•Synapses formed by neurogenin-2-induced human neurons exhibit short-term plasticity•After transplantation, neurogenin-2-induced human neurons are synaptically integrated
Zhang et al. describe an approach that converts human ESCs and iPSCs into functional neuron-like iN cells with nearly 100% yield and purity in less than 2 weeks by forced expression of a single transcription factor.
Toscana virus is a major cause of arboviral disease in humans in the Mediterranean basin during summer. However, early virus-host cell interactions and entry mechanisms remain poorly characterized. ...Investigating iPSC-derived human neurons and cell lines, we found that virus binding to the cell surface was specific, and 50% of bound virions were endocytosed within 10 min. Virions entered Rab5a+ early endosomes and, subsequently, Rab7a+ and LAMP-1+ late endosomal compartments. Penetration required intact late endosomes and occurred within 30 min following internalization. Virus entry relied on vacuolar acidification, with an optimal pH for viral membrane fusion at pH 5.5. The pH threshold increased to 5.8 with longer pre-exposure of virions to the slightly acidic pH in early endosomes. Strikingly, the particles remained infectious after entering late endosomes with a pH below the fusion threshold. Overall, our study establishes Toscana virus as a late-penetrating virus and reveals an atypical use of vacuolar acidity by this virus to enter host cells.
In copper mining, there are two main separation processes: leaching for oxidized minerals and flotation for sulfide minerals. In Chile, the increase of sulfide minerals in the deposits and the ...decrease of oxidized minerals have led to an increase in the investigation of flotation processes and the optimization of their associated operations. One of the concentration processes is the use of thickeners, whose main objective is to treat the tailings that leave the plants in pulp form with approximately 30% solids and obtain a pulp with a concentration greater than 50% with clear water flow. The recovery of water is the main goal, so knowing the concentration profiles of solids and sedimentation is crucial. However, the characteristics of the pulp and the operation of the thickeners are complex because a great variety of forms can be found in the concentration profile of said pulp. This limits conventional measurement techniques and makes it difficult to apply deterministic models to the solids profile, given the high nonlinearities and variability of the system. In this article, a solution is proposed by developing a sensor that allows the online estimation of sludge level and concentration of solids, based on a model of neural networks (with the model of Maxwell for dispersions), allowing to measure the solids profile regardless of the operating conditions. The structure selected has nine inputs with a hidden layer, two neurons, and two outputs being trained with tailings from Chuquicamata, obtaining the information from a 50 L pilot with 10-electrode bar of 60 cm of length, resulting in an estimation error of 0.8 cm with a network of 26 parameters.
Hundreds of L1CAM gene mutations have been shown to be associated with congenital hydrocephalus, severe intellectual disability, aphasia, and motor symptoms. How such mutations impair neuronal ...function, however, remains unclear. Here, we generated human embryonic stem (ES) cells carrying a conditional L1CAM loss-of-function mutation and produced precisely matching control and L1CAM-deficient neurons from these ES cells. In analyzing two independent conditionally mutant ES cell clones, we found that deletion of L1CAM dramatically impaired axonal elongation and, to a lesser extent, dendritic arborization. Unexpectedly, we also detected an ∼20-50% and ∼20-30% decrease, respectively, in the levels of ankyrinG and ankyrinB protein, and observed that the size and intensity of ankyrinG staining in the axon initial segment was significantly reduced. Overexpression of wild-type L1CAM, but not of the L1CAM point mutants R1166X and S1224L, rescued the decrease in ankyrin levels. Importantly, we found that the L1CAM mutation selectively decreased activity-dependent Na(+)-currents, altered neuronal excitability, and caused impairments in action potential (AP) generation. Thus, our results suggest that the clinical presentations of L1CAM mutations in human patients could be accounted for, at least in part, by cell-autonomous changes in the functional development of neurons, such that neurons are unable to develop normal axons and dendrites and to generate normal APs.
Deep brain temperature detection by hypothalamic warm-sensitive neurons (WSNs) has been proposed to provide feedback information relevant for thermoregulation. WSNs increase their action potential ...firing rates upon warming, a property that has been presumed to rely on the composition of thermosensitive ion channels within WSNs. Here, we describe a synaptic mechanism that regulates temperature sensitivity of preoptic WSNs and body temperature. Experimentally induced warming of the mouse hypothalamic preoptic area in vivo triggers body cooling. TRPM2 ion channels facilitate this homeostatic response and, at the cellular level, enhance temperature responses of WSNs, thereby linking WSN function with thermoregulation for the first time. Rather than acting within WSNs, we—unexpectedly—find TRPM2 to temperature-dependently increase synaptic drive onto WSNs by disinhibition. Our data emphasize a network-based interoceptive paradigm that likely plays a key role in encoding body temperature and that may facilitate integration of diverse inputs into thermoregulatory pathways.
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•Temperature in the hypothalamic preoptic area (POA) tracks body temperature in mice•TRPM2 participates in warmth detection in the POA in vivo•Presynaptic TRPM2 detects temperature increases to activate warm-sensitive neurons•Warming enhances inhibitory transmitter release via TRPM2 to mediate disinhibition
Kamm, Boffi, et al. found that the ion channel TRPM2 mediates detection of warm temperatures in the mouse hypothalamus. Specifically, TRPM2 enhances the thermosensitivity of hypothalamic warm-sensitive neurons (WSNs) via a presynaptic mechanism. This study highlights the role of WSNs and TRPM2 in body temperature homeostasis under hot environments.
Fast neurotransmitter release from ribbon synapses via Ca2+-triggered exocytosis requires tight coupling of L-type Ca2+ channels to release-ready synaptic vesicles at the presynaptic active zone, ...which is localized at the base of the ribbon. Here, we used genetic, electrophysiological, and ultrastructural analyses to probe the architecture of ribbon synapses by perturbing the function of RIM-binding proteins (RBPs) as central active-zone scaffolding molecules. We found that genetic deletion of RBP1 and RBP2 did not impair synapse ultrastructure of ribbon-type synapses formed between rod bipolar cells (RBCs) and amacrine type-2 (AII) cells in the mouse retina but dramatically reduced the density of presynaptic Ca2+ channels, decreased and desynchronized evoked neurotransmitter release, and rendered evoked and spontaneous neurotransmitter release sensitive to the slow Ca2+ buffer EGTA. These findings suggest that RBPs tether L-type Ca2+ channels to the active zones of ribbon synapses, thereby synchronizing vesicle exocytosis and promoting high-fidelity information transfer in retinal circuits.
The primary somatosensory cortex (S1) is a hub for body sensation of both innocuous and noxious signals, yet its role in somatosensation versus pain is debated. Despite known contributions of S1 to ...sensory gain modulation, its causal involvement in subjective sensory experiences remains elusive. Here, in mouse S1, we reveal the involvement of cortical output neurons in layers 5 (L5) and 6 (L6) in the perception of innocuous and noxious somatosensory signals. We find that L6 activation can drive aversive hypersensitivity and spontaneous nocifensive behavior. Linking behavior to neuronal mechanisms, we find that L6 enhances thalamic somatosensory responses, and in parallel, strongly suppresses L5 neurons. Directly suppressing L5 reproduced the pronociceptive phenotype induced by L6 activation, suggesting an anti-nociceptive function for L5 output. Indeed, L5 activation reduced sensory sensitivity and reversed inflammatory allodynia. Together, these findings reveal a layer-specific and bidirectional role for S1 in modulating subjective sensory experiences.
is a significant health problem worldwide due to multi-drug resistance issues and absence of an effective vaccine. Patients infected with
have not shown a better immune response in successive ...infections. This might be explained by the fact that
possesses several mechanisms to evade the innate and adaptative immune responses at different levels. Macrophages are a key cellular component in the innate immune response against microorganisms. The current information suggests that gonococcus can hijack the host response by mechanisms that involve the control of macrophages activity. In this mini review, we intend to condense the recent knowledge on the macrophage-
interactions with a focus on strategies developed by gonococcus to evade or to exploit immune response to establish a successful infection. Finally, we discuss the opportunities and challenges of therapeutics for controlling immune manipulation by
.
The P2X7 receptor, a member of the P2X purinergic receptor family, is a non-selective ion channel. Over the years, it has been associated with various biological functions, from modulating to ...regulating inflammation. However, its emerging role in antigen presentation has captured the scientific community's attention. This function is essential for the immune system to identify and respond to external threats, such as pathogens and tumor cells, through T lymphocytes. New studies show that the P2X7 receptor is crucial for controlling how antigens are presented and how T cells are activated. These studies focus on antigen-presenting cells, like dendritic cells and macrophages. This review examines how the P2X7 receptor interferes with effective antigen presentation and activates T cells and discusses the fundamental mechanisms that can affect the immune response. Understanding these P2X7-mediated processes in great detail opens up exciting opportunities to create new immunological therapies.
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