Lipid droplets (LDs) store neutral lipids and are integrated into a cellular metabolic network that relies on functional coupling with various organelles. Factors mediating efficient coupling and mechanisms regulating them remain unknown. Here, we conducted a global screen in to identify genes required for the functional coupling of LDs and other organelles during LD consumption. We show that LD utilization during growth resumption is coupled to vacuole homeostasis. ESCRT-, V-ATPase- and vacuole protein sorting-mutants negatively affect LD consumption, independent of lipophagy. Loss of ESCRT function leads to the accumulation of LD-derived diacylglycerol (DAG), preventing its conversion into phosphatidic acid (PA) and membrane lipids. In addition, channeling of DAG from LD-proximal sites to the vacuole is blocked. We demonstrate that utilization of LDs requires intact vacuolar signaling via TORC1 and its downstream effector Sit4p. These data suggest that vacuolar status is coupled to LD catabolism via TORC1-mediated regulation of DAG-PA interconversion and explain how cells coordinate organelle dynamics throughout cell growth.

Atrial dysfunction is a relatively common complication of acute myocarditis, although its pathophysiology is unclear. There is limited information on myocarditis-associated histological changes in the atria and how they develop in time. The aim of this study therefore was to investigate inflammation, fibrosis and viral genome in the atria in time after mild CVB3-induced viral myocarditis (VM) in mice. C3H mice (n = 68) were infected with 10 5 PFU of Coxsackievirus B3 (CVB3) and were compared with uninfected mice (n = 10). Atrial tissue was obtained at days 4, 7, 10, 21, 35 or 49 post-infection. Cellular infiltration of CD45+ lymphocytes, MAC3+ macrophages, Ly6G+ neutrophils and mast cells was quantified by (immuno)histochemical staining. The CVB3 RNA was determined by in situ hybridization, and fibrosis was evaluated by elastic van Gieson (EvG) staining. In the atria of VM mice, the numbers of lymphocytes on days 4 and 7 (p < .05) and days 10 (p < .01); macrophages on days 7 (p < .01) and 10 (p < .05); neutrophils on days 4 (p < .05); and mast cells on days 4 and 7 (p < .05) increased significantly compared with control mice and decreased thereafter to basal levels. No cardiomyocyte death was observed, and the CVB3 genome was detected in only one infected mouse on Day 4 post-infection. No significant changes in the amount of atrial fibrosis were found between VM and control mice. A temporary increase in inflammation is induced in the atria in the acute phase of CVB3induced mild VM, which may facilitate the development of atrial arrhythmia and contractile dysfunction.

Background Vasospasm is an important etiological factor in the induction of acute myocardial infarction (AMI). PeriVascular Nerve Fibres (PVNF) and PeriVascular Adipose Tissue (PVAT) play an important role in vasoregulation, although detailed information of their role in the heart is missing in AMI patients. In the present study we have analysed PVNF and PVAT in deceased AMI patients. Methods Sections of epicardial coronary arteries were obtained at autopsy from AMI patients (N=16) and controls without heart disease (N=7). Infarct age was between 3 and 6 hours old. Stenosis of epicardial coronary arteries was quantified in a HE stained slide. To analyse the intramyocardial vasculature samples were taken from the left ventricle of the heart (in AMI patients the infarcted area). Nerve fibres were stained using a specific S100 antibody. Putative activation of these nerves was stained using a specific antibody against neuropeptide Y (NPY). S100+ and NPY+ nerve fibres were quantified by light microscopy and were then calculated per square mm of the adventitia surface areas. PVAT was quantified using an Elastica Von Gieson (EvG) staining. Results Stenosis did not correlate with PVNF. AMI patients had a significant increase in PVNF in the epicardium but not in the myocardium. NPY was non-significantly increased in PVNF in the epicardium and myocardium in AMI patients compared with controls. PVAT was significantly decreased in AMI patients compared with controls. Conclusion The increase in PVNF in the epicardium and the decrease of PVAT in the myocardium suggest that they might play a role in AMI induction, independent of the atherosclerotic changed epicardial coronary arteries. Funding Acknowledgement Type of funding sources: None.