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Insulin release by pancreatic β cells plays a key role in regulating blood glucose levels in humans, and to understand the mechanism for insulin secretion may reveal therapeutic strategies for diabetes. We found that PI4KIIα transgenic (TG) mice have abnormal glucose tolerance and higher serum glucose levels than wild-type mice. Glucose-stimulated insulin secretion was significantly reduced in both PI4KIIα TG mice and PI4KIIα-overexpressing pancreatic β cell lines. A proximity-based biotin labeling technique, BioID, was used to identify proteins that interact with PI4KIIα, and the results revealed that PI4KIIα interacts with PKD and negatively regulates its activity. The effect of PI4KIIα on insulin secretion was completely rescued by altering PKD activity. PI4KIIα overexpression also worsened glucose tolerance in streptozotocin/high-fat diet-induced diabetic mice by impairing insulin secretion. Our study has shed new light on PI4KIIα function and mechanism in diabetes and identified PI4KIIα as an important regulator of insulin secretion.

Our previous studies indicate that phosphatidylinositol 4-kinase IIα can promote the growth of multi-malignant tumors via HER-2/PI3K and MAPK pathways. However, the molecular mechanisms of this pathway and its potential for clinical application remain unknown. In this study, we found that PI4KIIα could be an ideal combinatorial target for EGFR treatment via regulating EGFR degradation. Results showed that PI4KIIα knockdown reduced EGFR protein level, and the expression of PI4KIIα shows a strong correlation with EGFR in human breast cancer tissues (r= 0.77, P< 0.01). PI4KIIα knockdown greatly prolonged the effects and decreased the effective dosage of AG-1478, a specific inhibitor of EGFR. In addition, it significantly enhanced AG1478-induced inhibition of tumor cell survival and strengthened the effect of the EGFR-targeting anti-cancer drug Iressa in xenograft tumor models. Mechanistically, we found that PI4KIIα suppression increased EGFR ligand-independent degradation. Quantitative proteomic analysis by stable isotope labeling with amino acids in cell culture (SILAC) and LC-MS/MS suggested that HSP90 mediated the effect of PI4KIIα on EGFR. Furthermore, we found that combined inhibition of PI4KIIα and EGFR suppressed both PI3K/AKT and MAPK/ERK pathways, and resulted in downregulation of multiple oncogenes like PRDX2, FASN, MTA2, ultimately leading to suppression of tumor growth. Therefore, we conclude that combined inhibition of PI4KIIα and EGFR exerts a multiple anti-tumor effect. Dual inhibition of EGFR at protein and activity level via combinatorial blocking of PI4KIIα presents a novel strategy to combat EGFR-dependent tumors.

S-Nitros(yl)ation is a ubiquitous redox-based post-translational modification of protein cysteine thiols by nitric oxide or its derivatives, which transduces the bioactivity of nitric oxide (NO) by regulation of protein conformation, activity, stability, localization and protein-protein interactions. These years, more and more S-nitrosated proteins were identified in physiological and pathological processes and the number is still growing. Here we developed a database named SNObase (http://www.nitrosation.org), which collected S-nitrosation targets extracted from literatures up to June 1st, 2012. SNObase contained 2561 instances, and provided information about S-nitrosation targets, sites, biological model, related diseases, trends of S-nitrosation level and effects of S-nitrosation on protein function. With SNObase, we did functional analysis for all the SNO targets: In the gene ontology (GO) biological process category, some processes were discovered to be related to S-nitrosation (“response to drug”, “regulation of cell motion”) besides the previously reported related processes. In the GO cellular component category, cytosol and mitochondrion were both enriched. From the KEGG pathway enrichment results, we found SNO targets were enriched in different diseases, which suggests possible significant roles of S-nitrosation in the progress of these diseases. This SNObase means to be a database with precise, comprehensive and easily accessible information, an environment to help researchers integrate data with comparison and relevancy analysis between different groups or works, and also an SNO knowledgebase offering feasibility for systemic and global analysis of S-nitrosation in interdisciplinary studies.

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Despite decades of studies suggesting that the in vivoadipocyte progenitor resides within the vascular niche, the exact nature of this progenitor remains controversial because distinct studies have attributed adipogenic properties to multiple vascular cell types. Using Cre recombinases labeling distinct vascular lineages, we conduct parallel lineage tracing experiments to assess their degree of contribution to de novoadipogenesis. Although we detect occasional adipocytes that were lineage traced by endothelial or mural recombinases, these are rare events. On the other hand, platelet-derived growth factor receptor alpha (PDGFRα)-expressing adventitial or capsular fibroblasts make a significant contribution to adipocytes in all depots and experimental settings tested. Our data also suggest that fibroblasts transition to an intermediate beige adipocyte phenotype prior to differentiating to a mature white adipocyte. These observations, together with histological analyses revealing that adipose tissue fibroblasts express the mural cell marker PDGFRβ, harmonize a highly controversial field with implications for multiple human diseases, including the pandemic of obesity.