[Exploration for anti-enterovirus compounds and analysis on the mechanism of its inhibitory effect on virus infection]

Research progress of phosphatidylinositol 4-kinase and its inhibitors in inflammatory diseases

Phosphatidylinositol 4-kinase (PI4K) is a lipid kinase that can catalyze the transfer of phosphate group from ATP to the inositol ring of phosphatidylinositol (PtdIns) resulting in the phosphorylation of PtdIns at 4-OH sites, to generate phosphatidylinositol 4-phosphate (PI4P). Studies on biological functions reveal that PI4K is closely related to the occurrence and development of various inflammatory diseases such as obesity, cancer, viral infections, malaria, Alzheimer's disease, etc. PI4K-related inhibitors have been found to have the effects of inhibiting virus replication, anti-cancer, treating malaria and reducing rejection in organ transplants, among which MMV390048, an anti-malaria drug, has entered phase II clinical trial. This review discusses the classification, structure, distribution and related inhibitors of PI4K and their role in the progression of cancer, viral replication, and other inflammation induced diseases to explore their potential as therapeutic targets.

OSBP-Related Protein Family: Mediators of Lipid Transport and Signaling at Membrane Contact Sites

Oxysterol-binding protein (OSBP) and its related protein homologs, ORPs, constitute a conserved family of lipid-binding/transfer proteins (LTPs) expressed ubiquitously in eukaryotes. The ligand-binding domain of ORPs accommodates cholesterol and oxysterols, but also glycerophospholipids, particularly phosphatidylinositol-4-phosphate (PI4P). ORPs have been implicated as intracellular lipid sensors or transporters. Most ORPs carry targeting determinants for the endoplasmic reticulum (ER) and non-ER organelle membrane. ORPs are located and function at membrane contact sites (MCSs), at which ER is closely apposed with other organelle limiting membranes. Such sites have roles in lipid transport and metabolism, control of Ca(2+) fluxes, and signaling events. ORPs are postulated either to transport lipids over MCSs to maintain the distinct lipid compositions of organelle membranes, or to control the activity of enzymes/protein complexes with functions in signaling and lipid metabolism. ORPs may transfer PI4P and another lipid class bidirectionally. Transport of PI4P followed by its hydrolysis would in this model provide the energy for transfer of the other lipid against its concentration gradient. Control of organelle lipid compositions by OSBP/ORPs is important for the life cycles of several pathogenic viruses. Targeting ORPs with small-molecular antagonists is proposed as a new strategy to combat viral infections. Several ORPs are reported to modulate vesicle transport along the secretory or endocytic pathways. Moreover, antagonists of certain ORPs inhibit cancer cell proliferation. Thus, ORPs are LTPs, which mediate interorganelle lipid transport and coordinate lipid signals with a variety of cellular regimes.