3 research outputs found
Fine tuning Exo2, a small molecule inhibitor of secretion and retrograde trafficking pathways in mammalian cells
The small molecule 4-hydroxy-3-methoxybenzaldehyde (5,6,7,8-tetrahydro[1]benzothieno[2,3-
d]pyrimidin-4-yl)hydrazone (Exo2) stimulates morphological changes at the mammalian Golgi and
trans-Golgi network that are virtually indistinguishable from those induced by brefeldin A. Both
brefeldin A and Exo2 protect cells from intoxication by Shiga(-like) toxins by acting on other
targets that operate at the early endosome, but do so at the cost of high toxicity to target cells. The
advantage of Exo2 is that it is much more amenable to chemical modification and here we report a
range of Exo2 analogues produced by modifying the tetrahydrobenzothienopyrimidine core, the
vanillin moiety and the hydrazone bond that links these two. These compounds were examined for
the morphological changes they stimulated at the Golgi stack, the trans Golgi network and the
transferrin receptor-positive early endosomes and this activity correlated with their inherent
toxicity towards the protein manufacturing ability of the cell and their protective effect against
toxin challenge. We have developed derivatives that can separate organelle morphology, target
specificity, innate toxicity and toxin protection. Our results provide unique compounds with low
toxicity and enhanced specificity to unpick the complexity of membrane trafficking networks
Simple oxidation of pyrimidinylhydrazones to triazolopyrimidines and their inhibition of Shiga toxin trafficking
The oxidative cyclisation of a range of benzothieno[2,3-d]pyrimidine hydrazones (7a–j) to the 1,2,4-triazolo[4,3-c]pyrimidines (8a–j) catalysed by lithium iodide or to the 1,2,4-triazolo[1,5-c]pyrimidines (10a–j) with sodium carbonate is presented. A complementary synthesis of the 1,2,4-triazolo[1,5-c]pyrimidines starting from the amino imine 11 is also reported. The effect of these compounds on Shiga toxin (STx) trafficking in HeLa cells and comparison to the previously reported Exo2 is also detailed
An Exo2 derivative affects ER and Golgi morphology and vacuolar sorting in a tissue-specific manner in arabidopsis
We screened a panel of compounds derived from Exo2—a drug that perturbs post-Golgi compartments and trafficking in mammalian cells—for their effect on the secretory pathway in Arabidopsis root epidermal cells. While Exo2 and most related compounds had no significant effect, one Exo2 derivative, named LG8, induced severe morphological alterations in both the Golgi (at high concentrations) and the endoplasmic reticulum (ER). LG8 causes the ER to form foci of interconnecting tubules, which at the ultrastructural level appear similar to those previously reported in Arabidopsis roots after treatment with the herbicide oryzalin. In cotyledonary leaves, LG8 causes redistribution of a trans Golgi network (TGN) marker to the vacuole. LG8 affects the anterograde secretory pathway by inducing secretion of vacuolar cargo and preventing the brassinosteroid receptor BRI1 from reaching the plasma membrane. Uptake and arrival at the TGN of the endocytic marker FM4-64 is not affected. Unlike the ADP ribosylation factor-GTP exchange factor (ARF-GEF) inhibitor brefeldin A (BFA), LG8 affects these post-Golgi events without causing the formation of BFA bodies. Up to concentrations of 50 µm, the effects of LG8 are reversible