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    A complex array of inhibitory interneurons tightly controls hippocampal activity, but how such diversity specifically affects memory processes is not well understood. We find that a small subclass of type 1 cannabinoid receptor (CB1R)-expressing hippocampal interneurons determines episodic-like memory consolidation by linking dopamine D1 receptor (D1R) signaling to GABAergic transmission. Mice lacking CB1Rs in D1-positive cells (D1-CB1-KO) display impairment in long-term, but not short-term, novel object recognition memory (NOR). Re-expression of CB1Rs in hippocampal D1R-positive cells rescues this NOR deficit. Learning induces an enhancement of in vivo hippocampal long-term potentiation (LTP), which is absent in mutant mice. CB1R-mediated NOR and the associated LTP facilitation involve local control of GABAergic inhibition in a D1-dependent manner. This study reveals that hippocampal CB1R-/D1R-expressing interneurons control NOR memory, identifying a mechanism linking the diversity of hippocampal interneurons to specific behavioral outcomes.Alzheimer’s disease (AD) is a proteinopathy exhibiting aggregation of β-amyloid (Aβ) as amyloid plaques and tau as neurofibrillary tangles (NFTs), whereas primary tauopathies display only a tau pathology. Aβ toxicity is mediated by Fyn kinase in a tau-dependent process; however, whether Fyn controls tau pathology in diseases that lack Aβ pathology remains unexplored. To address this, we generate the Tg/Fyn-/- mouse, which couples mutant tau overexpression with Fyn knockout. Surprisingly, Tg/Fyn-/- mice exhibit a near-complete ablation of NFTs, alongside reduced tau hyperphosphorylation, altered tau solubility, and diminished synaptic tau accumulation. Furthermore, Tg/Fyn-/- brain lysates elicit less tau seeding in tau biosensor cells. Lastly, the fibrillization of tau is boosted by its pseudophosphorylation at the Fyn epitope Y18. Together, this identifies Fyn as a key regulator of tau pathology independently of Aβ-induced toxicity and thereby represents a potentially valuable therapeutic target for not only AD but also tauopathies more generally.Type I interferon (IFN) plays an essential role in the host innate immune responses. Several ubiquitin-conjugating enzyme (E2) family members were reported to regulate type I IFN production and host antiviral immune responses. However, the molecular mechanisms are still not fully understood. Here, we report that UBE2S acts as a negative regulator in the type I IFN signaling pathway. selleck Ectopic expression of UBE2S inhibits host antiviral immune responses and enhances viral replications, whereas deficiency of UBE2S enhances host antiviral immune responses and suppresses viral replications both in vitro and in vivo. Inhibition of type І IFN production by UBE2S is independent on its E2 and E3 enzymic activity. Mechanistically, UBE2S interacts with TBK1 and recruits ubiquitin-specific protease 15 (USP15) to remove Lys63 (K63)-linked polyubiquitin chains of TBK1. Our findings reveal a role of the UBE2S-USP15-TBK1 axis in the regulation of host antiviral innate immune responses.The islets of Langerhans are dynamic structures that can change in size, number of cells, and molecular function in response to physiological and pathological stress. Molecular cues originating from the surrounding “peri-islet” acinar cells that could facilitate this plasticity have not been explored. selleck Here, we combine single-molecule transcript imaging in the intact pancreas and transcriptomics to identify spatial heterogeneity of acinar cell gene expression. We find that peri-islet acinar cells exhibit a distinct molecular signature in db/db diabetic mice that includes upregulation of trypsin family genes and elevated mTOR activity. This zonated expression program seems to be induced by CCK that is secreted from islet cells. Elevated peri-islet trypsin secretion could facilitate the islet expansion observed in this model via modulation of the islet capsule matrix components. Our study highlights a molecular axis of communication between the pancreatic exocrine and endocrine compartments that may be relevant to islet expansion.VSV fusion machinery, like that of many other enveloped viruses, is triggered at low pH in endosomes after virion endocytosis. It was suggested that some histidines could play the role of pH-sensitive switches. By mutating histidine residues H22, H60, H132, H162, H389, H397, H407, and H409, we demonstrate that residues H389 and D280, facing each other in the six-helix bundle of the post-fusion state, and more prominently H407, located at the interface between the C-terminal part of the ectodomain and the fusion domain, are crucial for fusion. Passages of recombinant viruses bearing mutant G resulted in the selection of compensatory mutations. Thus, the H407A mutation in G resulted in two independent compensatory mutants, L396I and S422I. Together with a crystal structure of G, presented here, which extends our knowledge of G pre-fusion structure, this indicates that the conformational transition is initiated by refolding of the C-terminal part of the G ectodomain.Recycling of synaptic vesicles (SVs) at presynaptic terminals is required for sustained neurotransmitter release. Although SV endocytosis is a rate-limiting step for synaptic transmission, it is unclear whether the rate of the subsequent SV refilling with neurotransmitter also influences synaptic transmission. By analyzing vesicular glutamate transporter 1 (VGLUT1)-deficient calyx of Held synapses, in which both VGLUT1 and VGLUT2 are co-expressed in wild-type situation, we found that VGLUT1 loss causes a drastic reduction in SV refilling rate down to ∼25% of wild-type values, with only subtle changes in basic synaptic parameters. Strikingly, VGLUT1-deficient synapses exhibited abnormal synaptic failures within a few seconds during high-frequency repetitive firing, which was recapitulated by manipulating presynaptic Cl- concentrations to retard SV refilling. Our data show that the speed of SV refilling can be rate limiting for synaptic transmission under certain conditions that entail reduced VGLUT levels during development as well as various neuropathological processes.

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