Regulation of Mammalian Autophagy by Class II and III PI 3-Kinases through PI3P Synthesis

Synthesis of phosphatidylinositol-3-phosphate (PI3P) by Vps34, a class III phosphatidylinositol 3-kinase (PI3K), is critical for the initial steps of autophagosome (AP) biogenesis. Although Vps34 is the sole source of PI3P in budding yeast, mammalian cells can produce PI3P through alternate pathways, including direct synthesis by the class II PI3Ks; however, the physiological relevance of these alternate pathways in the context of autophagy is unknown. Here we generated Vps34 knockout mouse embryonic fibroblasts (MEFs) and using a higher affinity 4x-FYVE finger PI3P-binding probe found a Vps34-independent pool of PI3P accounting for ~35% of the total amount of this lipid species by biochemical analysis. Importantly, WIPI-1, an autophagy-relevant PI3P probe, still formed some puncta upon starvation-induced autophagy in Vps34 knockout MEFs. Additional characterization of autophagy by electron microscopy as well as protein degradation assays showed that while Vps34 is important for starvation-induced autophagy there is a significant component of functional autophagy occurring in the absence of Vps34. Given these findings, class II PI3Ks (α and β isoforms) were examined as potential positive regulators of autophagy. Depletion of class II PI3Ks reduced recruitment of WIPI-1 and LC3 to AP nucleation sites and caused an accumulation of the autophagy substrate, p62, which was exacerbated upon the concomitant ablation of Vps34. Our studies indicate that while Vps34 is the main PI3P source during autophagy, class II PI3Ks also significantly contribute to PI3P generation and regulate AP biogenesis

Atropisomeric Chiral Diiododienes (Z,Z)-2,3-Di(1-iodoalkylidene)tetralins : Synthesis, Enantiomeric Resolution, and Application in Asymmetric Catalysis

The C2-symmetric tetralin-fused 1,4-diiodo-1,3-butadiene derivatives, (Z,Z)-2,3-di(1-iodoalkylidene)tetralin 1a-c, are atropisomeric and can be resolved into the two persistent axially chiral enantiomers by HPLC on a chiral stationary phase. The enantiomerically pure compounds can serve as chiral organocatalysts for dearomatizing spirolactonization to show good performances in up to 73 % ee

Quantitative Determination of Click Reaction in the Presence of Glycine Derivatives and in Dilute Solution

The click reaction is one of the latest techniques for the functional analysis of bioactive compounds and the analysis makes novel concepts and strategies for medicinal chemistry. N-methylated glycine derivatives have inhibitory activity for the click reaction in direct Cu(I) system because of decrease of Cu(I) concentration. The Cu(I) concentration recovered effectively by sodium ascorbate. Quantitative determination of click reaction at various ligand concentrations revealed that the decrease in reaction yields was observed in a substrate concentration-dependent manner

Quantitative Analysis of Cu(I) Concentration in Click Chemistry : Biotinylation at Side Chain of Propargylglycine Using Click Chemistry under Heating Conditions

The click reaction is one of the latest techniques for the chemical modification of bioactive compounds. Chemical modifications of α-amino acid side chains are gaining significance as useful and important tools for biochemical research. Biotinylation at side chain of propargylglycine using click reaction was examined. The detail quantitative analysis of Cu(I) concentration are performed to proceed the click reaction effectively

Ole1, fatty acid desaturase, is required for Atg9 delivery and isolation membrane expansion during autophagy in Saccharomyces cerevisiae

Macroautophagy, a major degradation pathway of cytoplasmic components, is carried out through formation of a double-membrane structure, the autophagosome. Although the involvement of specific lipid species in the formation process remains largely obscure, we recently showed that mono-unsaturated fatty acids (MUFA) generated by stearoyl-CoA desaturase 1 (SCD1) are required for autophagosome formation in mammalian cells. To obtain further insight into the role of MUFA in autophagy, in this study we analyzed the autophagic phenotypes of the yeast mutant of OLE1, an orthologue of SCD1. Δole1 cells were defective in nitrogen starvation-induced autophagy, and the Cvt pathway, when oleic acid was not supplied. Defects in elongation of the isolation membrane led to a defect in autophagosome formation. In the absence of Ole1, the transmembrane protein Atg9 was not able to reach the pre-autophagosomal structure (PAS), the site of autophagosome formation. Thus, autophagosome formation requires Ole1 during the delivery of Atg9 to the PAS/autophagosome from its cellular reservoir

Synthesis of Photoreactive 2-Phenethylamine Derivatives : Synthesis of Adenosine Derivatives Enabling Functional Analysis of Adenosine Receptors by Photoaffinity Labeling

2-Phenylethylamine is well known as a substructure of many biologically active compounds, and the synthesis of its photoreactive derivatives to allow the analysis of biological functions is reported. This allowed us to synthesise ligands for adenosine receptors, which have many functional roles in biology and have been extensively studied for their many roles in maintaining homeostasis. Adenosine is one of the most common biochemical compounds, but photoaffinity labeling has not yet been used to study adenosine receptors. Synthetic methods for producing photoreactive adenosine derivatives that can be used with adenosine receptors were established for the photophores phenyl azide and benzophenone. The effect of the introduction of the photoreactive components was determined using an adenosine receptor assay