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The reversible switch of Candida albicans between unicellular yeast and multicellular hyphal growth is accompanied by a well-studied hypha-associated gene expression, encoding virulence factors like adhesins, toxins, or nutrient scavengers. The investigation of this gene expression consequently led to fundamental insights into the pathogenesis of this fungus.

The yeast-to-hypha transition is a key virulence attribute of the opportunistic human fungal pathogen Candida albicans, since it is closely tied to infection-associated processes such as tissue invasion and escape from phagocytes. While the nature of hypha-associated gene expression required for fungal virulence has been thoroughly investigated, potential morphotype-dependent activity of metabolic pathways remained unclear. Here, we combined global transcriptome and metabolome analyses for the wild-type SC5314 and the hypha-defective

Membrane phospholipids affect GLUT function in RBC but the role of their large intercellular S1P pool is unknown. We show that altering S1P content by intervening in its precursor uptake, synthesis and efflux had major impacts on RBC glucose uptake and glycolysis. We identified the mechanism as direct activation of PP2A by S1P leading to cell-surface GLUT reduction. This mechanism was highly dynamic as it responded to metabolic cues from the environment by regulating intracellular S1P and thereby glucose uptake, hence counteracting pathophysiological conditions such as diabetes. Accordingly, RBC from hyperglycemic mice and humans with diabetes had higher S1P, Sphk1 and PP2A activities, and lower cell-surface GLUTs. Proof of concept is provided by the resistance of RBC lacking the main S1P exporter MFSD2B to pathological HbA1c increases in hyperglycemia. This mechanism may also be functional in other insulin-independent tissues and could be pharmacologically exploited by existing S1P homeostasis-modifying drugs.

Loss of active synapses and alterations in membrane lipids are crucial events in physiological aging as well as in neurodegenerative disorders. Both are related to the abnormal aggregation of amyloid-beta (Aβ) species, generally known as amyloidosis. There are two major known human Aβ species: Aβ

Sphingosine-1-phosphate (S1P) is a constituent of high-density lipoproteins (HDL) that contributes to their beneficial effects. We have shown decreased HDL-S1P in coronary artery disease (CAD) but its functional relevance remains unclear.This study investigated the functional consequences of reduced HDL-S1P content in CAD and tested if increasing it may improve or restore HDL function.Human HDL from healthy and CAD subjects, as well as mouse HDL, were isolated by ultracentrifugation. HDL-S1P-dependent activation of cell-signaling pathways and induction of vasodilation were examined in vitro and in isolated arteries using native and S1P-loaded HDL, S1P receptor antagonists, and S1P-blocking antibodies.HDL-S1P-dependent signaling was clearly impaired and S1P content reduced in CAD-HDL as compared to healthy HDL. Both healthy and CAD-HDL could be efficiently and equally well loaded with S1P from cellular donors and plasma. S1P-loading greatly improved HDL signaling and vasodilatory potential in pre-contracted arteries and completely corrected the defects inherent to CAD-HDL. HDL-S1P content and uptake was reduced by oxidation and was lower in HDL3 than HDL2. Loading with S1P in vitro and in vivo fully replenished the virtually absent S1P content of apolipoprotein M-deficient HDL and restored their defective signaling. Infusion of erythrocyte-associated C17-S1P in mice led to its rapid and complete uptake by HDL providing a means to directly S1P-load HDL in vivo.Reduced HDL-S1P content contributes to HDL dysfunction in CAD. It can be efficiently increased by S1P-loading in vitro and in vivo, providing a novel approach to correcting HDL dysfunction in CAD.