Multidomain scaffolding proteins organize the molecular machinery of neurotransmitter vesicle dynamics during synaptogenesis and synaptic activity. We find that domains of five active zone proteins converge on an interaction node that centers on the N-terminal region of Munc13-1 and includes the zinc-finger domain of Rim1, the C-terminal region of Bassoon, a segment of CAST1/ELKS2, and the third coiled-coil domain (CC3) of either Aczonin/Piccolo or Bassoon. This multidomain complex may constitute a center for the physical and functional integration of the protein machinery at the active zone. An additional connection between Aczonin and Bassoon is mediated by the second coiled-coil domain of Aczonin. Recombinant Aczonin-CC3, expressed in cultured neurons as a green fluorescent protein fusion protein, is targeted to synapses and suppresses vesicle turnover, suggesting involvements in synaptic assembly as well as activity. Our findings show that Aczonin, Bassoon, CAST1, Munc13, and Rim are closely and multiply interconnected, they indicate that Aczonin-CC3 can actively participate in neurotransmitter vesicle dynamics, and they highlight the N-terminal region of Munc13-1 as a hub of protein interactions by adding three new binding partners to its mechanistic potential in the control of synaptic vesicle priming.

No abstract

No abstract

Summary Previous work on various organs and tissues has shown that ischemic preconditioning protects against reperfusion injury in these organs and also against secondary effects in the lung. In contrast, the purpose of this study was to investigate the effects of preconditioning in a remote organ (hind limb ischemia) on an ischemia/reperfusion (I/R) treatment of the lung itself. A porcine model of in situ left lung ischemia (90 min) and reperfusion (5 h) was used. Systemic preconditioning was induced by clamping the left common femoral artery (3 × 5 min). Lung injury was assessed in terms of pulmonary vascular resistance, pulmonary artery pressure, pulmonary venous and arterial pO2, and tissue macrophage counts. The zymosan‐stimulated release of reactive oxygen species (ROS) in whole blood was determined by a chemiluminometric procedure. Inflammatory cytokines (interleukin‐1β and interleukin‐6) were measured in arterial plasma as indicators of a systemic inflammatory reaction. Preconditioning by hind limb ischemia completely prevented the I/R‐induced functional impairment of the lung, the pulmonary hypertension and the reduced oxygenation capacity. The plasma levels of interleukin‐1β and the macrophage counts in preconditioned animals were reduced to control values, whereas the levels of interleukin‐6 and the release of ROS were not affected by preconditioning. In conclusion, systemic preconditioning by repeated hind limb ischemia protects against acute I/R injury of the lung but not against all indices of reperfusion‐associated systemic inflammation.

No abstract