TMEM55A-mediated PI5P signaling regulates α-cell actin depolymerization and glucagon secretion.

Diabetes is associated with the dysfunction of glucagon-producing pancreatic islet α-cells, although the underlying mechanisms regulating glucagon secretion and α-cell dysfunction remain unclear. While insulin secretion from pancreatic β-cells has long been known to be partly controlled by intracellular phospholipid signaling, very little is known about the role of phospholipids in glucagon secretion. Here we show that TMEM55A, a lipid phosphatase that dephosphorylates phosphatidylinositol-4,5-bisphosphate (PIP2) to phosphatidylinositol-5-phosphate (PI5P), regulates α-cell exocytosis and glucagon secretion.

High H Solubility of Perfluorocarbon Solvents and Their Use in Reversible Polarization Transfer from -Hydrogen.

This research uses perfluorocarbons (PFCs) as effective alternatives to traditional toxic solvents in reversible -hydrogen-induced polarization (PHIP) for NMR signal enhancement. Hydrogen solubility in PFCs is shown here to be an order of magnitude higher than in typical organic solvents by determination of Henry's constants. We demonstrate how this high H solubility enables the PFCs to deliver substantial polarization transfer from -hydrogen, achieving up to 2400-fold signal gains for H NMR detection and 67,000-fold (22% polarization) for N NMR detection at 9.

Iridium trihydride and tetrahydride complexes and their role in catalytic polarisation transfer from hydrogen to pyruvate.

This work details how the unusual iridium tetrahydride [Ir(H)(IMes)(sulfoxide)]Na and trihydride [Ir(H)(IMes)(sulfoxide)] can be formed in a solvent dependent reaction of [IrCl(COD)(IMes)] with sulfoxide (dimethyl or methylphenyl), base, and H. In the case of dimethyl sulfoxide, the four hydride ligands of the tetrahydride are equivalent, and the IMes and sulfoxide ligands mutually . However, for phenyl methyl sulfoxide, this isomer of the tetrahydride forms alongside its counterpart where the remarkable symmetry breaking effect of the sulfoxide leads to it presenting four chemically distinct hydride ligands.