Dopamine-glutamate interactions in the neostriatum determine psychostimulant action, but the underlying molecular mechanisms remain elusive. Here we found that dopamine stimulation by cocaine enhances a heteroreceptor complex formation between dopamine D2 receptors (D2R) and NMDA receptor NR2B subunits in the neostriatum in vivo. The D2R-NR2B interaction is direct and occurs in the confined postsynaptic density microdomain of excitatory synapses. The enhanced D2R-NR2B interaction disrupts the association of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) with NR2B, reduces NR2B phosphorylation at a CaMKII-sensitive site (Ser1303), and inhibits NMDA receptor-mediated currents in medium-sized striatal neurons. Furthermore, the regulated D2R-NR2B interaction is critical for constructing behavioral responsiveness to cocaine. Our findings here uncover a direct and dynamic D2R-NR2B interaction in striatal neurons in vivo. This type of dopamine-glutamate integration at the receptor level may be responsible for synergistically inhibiting the D2R-mediated circuits in the basal ganglia and fulfilling the stimulative effect of psychostimulants.

Cytokine storm and multi-organ failure are the main causes of SARS-CoV-2-related death. However, the origin of excessive damages caused by SARS-CoV-2 remains largely unknown. Here we show that the SARS-CoV-2 envelope (2-E) protein alone is able to cause acute respiratory distress syndrome (ARDS)-like damages in vitro and in vivo. 2-E proteins were found to form a type of pH-sensitive cation channels in bilayer lipid membranes. As observed in SARS-CoV-2-infected cells, heterologous expression of 2-E channels induced rapid cell death in various susceptible cell types and robust secretion of cytokines and chemokines in macrophages. Intravenous administration of purified 2-E protein into mice caused ARDS-like pathological damages in lung and spleen. A dominant negative mutation lowering 2-E channel activity attenuated cell death and SARS-CoV-2 production. Newly identified channel inhibitors exhibited potent anti-SARS-CoV-2 activity and excellent cell protective activity in vitro and these activities were positively correlated with inhibition of 2-E channel. Importantly, prophylactic and therapeutic administration of the channel inhibitor effectively reduced both the viral load and secretion of inflammation cytokines in lungs of SARS-CoV-2-infected transgenic mice expressing human angiotensin-converting enzyme 2 (hACE-2). Our study supports that 2-E is a promising drug target against SARS-CoV-2.

Homonuclear and heteronuclear 2D NMR methods are used to study two triple-helical peptides. One peptide, (POG)10, is considered to be the most stable prototype of a triple helix. The second peptide, (POG)3ITGARGLAGPOG(POG)3 (denoted T3-785), was designed to model an imino acid poor region of collagen and contains 12 residues from near the unique collagenase cleavage site in type III collagen. Both peptides associated as trimers, with melting temperatures of 60 degrees C for (POG)10 and 25 degrees C for the T3-785 peptide. Sequence-specific assignments were made for a tripeptide unit POG in (POG)10, and 80% of the POG triplets are found to be in an equivalent environment. In T3-785, with nonrepeating X-Y-Gly units incorporated in the sequence, the three chains of the homotrimer can be distinguished from one another by NMR. The solution conformation of (POG)10 is very similar to the model derived from X-ray fiber diffraction data, although the peptide contains less ordered regions at the peptide ends. In the trimer from of T3-785, the central residues of the three chains are closely packed, and the data are consistent with a triple-helical model with a one-residue stagger of three parallel chains. For T3-785, in contrast to (POG)10, there are also resonances from a less ordered form, which are probably due to the presence of a small amount of monomer. The similarity of the backbone conformations of T3-785 and (POG)10 suggests that an alternative conformation is not present in the imino acid poor region.

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