Neuronal communication relies on the tightly controlled fusion of synaptic vesicles at nerve terminals, which results in the release of neurotransmitters with strict temporal and quantal precision. At rest, synaptic vesicle fusion is inhibited (Brunger et al., 2018). Action potential-mediated opening of voltage-gated Ca 2+ channels results in Ca 2+ influx into the nerve terminal, creating a Ca 2+ nanodomain that triggers the fusion of vesicles that are docked and primed at the plasma membrane, thereby evoking fast synchronous neurotransmitter release (Chanaday & Kavalali, 2018;Sudhof, 2013).Vesicles can additionally fuse asynchronously following evoked synchronous release and some spontaneous fusion of vesicles also occurs, though this is clamped (Chanaday & Kavalali, 2018).These processes are under exquisite regulatory control, preventing excessive neurotransmitter release and ensuring high-fidelity neuronal communication (Brunger et al., 2019;Rizo, 2018;; perturbation of this regulation can lead to a breakdown in neurotransmission.A range of presynaptic proteins are required to orchestrate these precision events. The SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complex, composed of the vesicular SNARE protein (v-SNARE) synaptobrevin and the target membrane SNARE proteins (t-SNAREs) syntaxin-1 and SNAP-25 (synaptosomal-associated protein-25), is the core fusion machinery that provides the energy required for fusion of synaptic vesicles with the plasma membrane (Weber et al., 1998). Several other key components regulate synaptic vesicle exocytosis in physiological environments (Brunger et al., 2019;Sudhof, 2014). SNARE complex assembly is orchestrated by Munc13 and Munc18, and further

Post-transcriptional regulation mechanisms control mRNA stability or translational efficiency via ribosomes, and recent evidence indicates that it is a major determinant of the accurate levels of cytokine mRNAs. Transcriptional regulation of Tnf has been well studied and found to be important for the rapid induction of Tnf mRNA and regulation of the acute phase of inflammation, whereas study of its post-transcriptional regulation has been largely limited to the role of the AU-rich element (ARE), and to a lesser extent, to that of the constitutive decay element (CDE). We have identified another regulatory element (NRE) in the 3 0 UTR of Tnf and demonstrate that ARE, CDE, and NRE cooperate in vivo to efficiently downregulate Tnf expression and prevent autoimmune inflammatory diseases. We also show that excessive TNF may lead to embryonic death.

BPSM1 (Bone phenotype spontaneous mutant 1) mice develop severe polyarthritis and heart valve disease as a result of a spontaneous mutation in the Tnf gene. In these mice, the insertion of a retrotransposon in the 3' untranslated region of Tnf causes a large increase in the expression of the cytokine. We have found that these mice also develop inducible bronchus-associated lymphoid tissue (iBALT), as well as nodular lymphoid hyperplasia (NLH) in the bone marrow. Loss of TNFR1 prevents the development of both types of follicles, but deficiency of TNFR1 in the hematopoietic compartment only prevents the iBALT and not the NLH phenotype. We show that the development of arthritis and heart valve disease does not depend on the presence of the tertiary lymphoid tissues. Interestingly, while loss of IL-17 or IL-23 limits iBALT and NLH development to some extent, it has no effect on polyarthritis or heart valve disease in BPSM1 mice.