Decreased activity of acetyl-CoA carboxylase during chemically induced neutrophilic differentiation of human promyelocytic leukemia cells

Roles of vitamin A in the regulation of fatty acid synthesis

Dietary macronutrients and micronutrients play important roles in human health. On the other hand, the excessive energy derived from food is stored in the form of triacylglycerol. A variety of dietary and hormonal factors affect this process through the regulation of the activities and expression levels of those key player enzymes involved in fatty acid biosynthesis such as acetyl-CoA carboxylase, fatty acid synthase, fatty acid elongases, and desaturases. As a micronutrient, vitamin A is essential for the health of humans. Recently, vitamin A has been shown to play a role in the regulation of glucose and lipid metabolism. This review summarizes recent research progresses about the roles of vitamin A in fatty acid synthesis. It focuses on the effects of vitamin A on the activities and expression levels of mRNA and proteins of key enzymes for fatty acid synthesis in vitro and in vivo. It appears that vitamin A status and its signaling pathway regulate the expression levels of enzymes involved in fatty acid synthesis. Future research directions are also discussed.

Transcriptomine, a web resource for nuclear receptor signaling transcriptomes

The nuclear receptor (NR) superfamily of ligand-regulated transcription factors directs ligand- and tissue-specific transcriptomes in myriad developmental, metabolic, immunological, and reproductive processes. The NR signaling field has generated a wealth of genome-wide expression data points, but due to deficits in their accessibility, annotation, and integration, the full potential of these studies has not yet been realized. We searched public gene expression databases and MEDLINE for global transcriptomic datasets relevant to NRs, their ligands, and coregulators. We carried out extensive, deep reannotation of the datasets using controlled vocabularies for RNA Source and regulating molecule and resolved disparate gene identifiers to official gene symbols to facilitate comparison of fold changes and their significance across multiple datasets. We assembled these data points into a database, Transcriptomine (http://www.nursa.org/transcriptomine), that allows for multiple, menu-driven querying strategies of this transcriptomic "superdataset," including single and multiple genes, Gene Ontology terms, disease terms, and uploaded custom gene lists. Experimental variables such as regulating molecule, RNA Source, as well as fold-change and P value cutoff values can be modified, and full data records can be either browsed or downloaded for downstream analysis. We demonstrate the utility of Transcriptomine as a hypothesis generation and validation tool using in silico and experimental use cases. Our resource empowers users to instantly and routinely mine the collective biology of millions of previously disparate transcriptomic data points. By incorporating future transcriptome-wide datasets in the NR signaling field, we anticipate Transcriptomine developing into a powerful resource for the NR- and other signal transduction research communities.

Apicidin, a histone deacetylase inhibitor, induces differentiation of HL-60 cells

The fungal metabolite apicidin (cyclo(N-O-methyl-L-tryptophanyl-L-isoleucinyl-D-pipecolinyl-L-2-amino-8-oxodecanoyl)) inhibited the growth of HL-60 cells in a concentration-dependent manner (100-1000 nM). At higher concentrations (>300 nM), cell death was induced. At 100 nM, it induced hyperacetylation of histone H4 time-dependently, while trichostatin A induced transient hyperacetylation. Apicidin (10-100 nM) increased the cells having nitroblue tetrazolium-reducing activity and expressing CD11b but not CD14 and CD15. The expression of CD11b by apicidin was long lasting, while that by trichostatin A was transient. In K562 cells, apicidin at 10-100 nM did not inhibit cell growth nor express CD11b, CD14 and CD15. Our findings indicate that apicidin inhibits proliferation and induces the early stage of differentiation of HL-60 cells.

Graded increase in probability of eosinophilic differentiation of HL-60 promyelocytic leukemia cells induced by culture under alkaline conditions

HL-60 cells differentiate primarily to eosinophils instead of neutrophils when cultured with butyric acid if they have previously been cultured under alkaline conditions (pH 7.6). To determine the nature of the process by which this occurs, a group of single-cell derived clones was produced from HL-60 cells after prolonged passage under alkaline conditions. When these clones were induced to mature with butyric acid, each clone demonstrated a characteristic proportion of mature eosinophils and neutrophils. This property was stable for multiple passages. Subclones derived from these clones also demonstrated the same probability of differentiating to an eosinophil as their parent clones. Reversion toward neutrophilic differentiation gradually occurred after several months of culture under conditions of reduced pH. The most highly directed clones demonstrated 90-95% eosinophilic differentiation and continued to differentiate primarily to eosinophils after seven months of culture at the reduced pH. Thus, in HL-60 cells, the tendency to differentiate to an eosinophil is a long-lived, heritable, continuously variable phenotype that is inducible in cells by culture under alkaline conditions. This tendency persists for prolonged periods after the alkaline conditions are removed, but may gradually revert toward neutrophilic differentiation with time.