The Role of Mycotoxins in Interactions between and Growing in Saprophytic Cultures and Co-Infecting Maize Plants.

() and () co-occur in infected plants and plant residues. In maize ears, the growth of is stimulated while is suppressed. To elucidate the role of mycotoxins in these effects, we used mutants with disrupted synthesis of nivalenol (NIV) and deoxynivalenol (DON) and a mutant with disrupted synthesis of fumonisins to monitor fungal growth in mixed cultures in vitro and in co-infected plants by real-time PCR.

Angiopoietin-like 4 Is a Wnt Signaling Antagonist that Promotes LRP6 Turnover.

Angiopoietin-like 4 (ANGPTL4) is a secreted signaling protein that is implicated in cardiovascular disease, metabolic disorder, and cancer. Outside of its role in lipid metabolism, ANGPTL4 signaling remains poorly understood. Here, we identify ANGPTL4 as a Wnt signaling antagonist that binds to syndecans and forms a ternary complex with the Wnt co-receptor Lipoprotein receptor-related protein 6 (LRP6).

RAB8B is required for activity and caveolar endocytosis of LRP6.

Wnt/β-catenin signaling plays an important role in embryonic development and adult tissue homeostasis. When Wnt ligands bind to the receptor complex, LRP5/6 coreceptors are activated by phosphorylation and concomitantly endocytosed. In vertebrates, Wnt ligands induce caveolin-dependent endocytosis of LRP6 to relay signal downstream, whereas antagonists such as Dickkopf promote clathrin-dependent endocytosis, leading to inhibition.

LGR4 and LGR5 are R-spondin receptors mediating Wnt/β-catenin and Wnt/PCP signalling.

R-spondins are secreted Wnt signalling agonists, which regulate embryonic patterning and stem cell proliferation, but whose mechanism of action is poorly understood. Here we show that R-spondins bind to the orphan G-protein-coupled receptors LGR4 and LGR5 by their Furin domains. Gain- and loss-of-function experiments in mammalian cells and Xenopus embryos indicate that LGR4 and LGR5 promote R-spondin-mediated Wnt/β-catenin and Wnt/PCP signalling.

Genetic selection designed to stabilize proteins uncovers a chaperone called Spy.

To optimize the in vivo folding of proteins, we linked protein stability to antibiotic resistance, thereby forcing bacteria to effectively fold and stabilize proteins. When we challenged Escherichia coli to stabilize a very unstable periplasmic protein, it massively overproduced a periplasmic protein called Spy, which increases the steady-state levels of a set of unstable protein mutants up to 700-fold. In vitro studies demonstrate that the Spy protein is an effective ATP-independent chaperone that suppresses protein aggregation and aids protein refolding.