Small zebrafish in a big chemical pond

The number of possible small organic molecules of different structure is virtually limitless. One of the main goals of chemical biologists is to identify, from this “chemical space”, entities that affect biological processes or systems in a specific manner. This can lead to a better understanding of the regulation and components of various biological machineries, as well as provide insights into efficacious therapeutic targets and drug candidates. However, the challenges confronting chemical biologists are multiple. How do we efficiently identify compounds that possess desirable activities without unwanted off‐target effects? Once a candidate compound has been found, how do we determine its mode of action? In this Prospects piece, we call attention to recent studies using embryonic and larval zebrafish to illustrate the breadth and depth of questions in chemical biology that may be addressed using this model, and hope that they can serve as catalysts for future investigational ideas. J. Cell. Biochem. 113: 2208–2216, 2012. © 2012 Wiley Periodicals, Inc.     

Second-generation aryl isonitrile compounds targeting multidrug-resistant Staphylococcus aureus

Antibiotic resistance remains a major global public health threat that requires sustained discovery of novel antibacterial agents with unexploited scaffolds. Structure-activity relationship of the first-generation aryl isonitrile compounds we synthesized led to an initial lead molecule that informed the synthesis of a second-generation of aryl isonitriles. From this new series of 20 compounds, three analogues inhibited growth of methicillin-resistant Staphylococcus aureus (MRSA) (from 1 to 4?µM) and were safe to human keratinocytes. Compound 19, with an additional isonitrile group exhibited improved activity against MRSA compared to the first-generation lead compound. This compound emerged as a candidate worthy of further investigation and further reinforced the importance of the isonitrile functionality in the compounds’ anti-MRSA activity. In a murine skin wound model, 19 significantly reduced the burden of MRSA, similar to the antibiotic fusidic acid. In summary, 19 was identified as a new lead aryl isonitrile compound effective against MRSA.     

Enzymatic characterization of class I DAD1-like acylhydrolase members targeted to chloroplast in Arabidopsis

In Arabidopsis, there are at least seven class I acylhydrolase members, which have a putative N-terminal chloroplast-targeting signal. Here, we show that all seven class I proteins are localized to the chloroplasts and hydrolyze phosphatidylcholine at the sn-1 position. However, based on their activities toward various lipids, Arabidopsis class I enzymes could be further divided into three sub-groups by substrate specificity, one with phospholipase-specific activity, another with phospholipase and galactolipase activities, and the other with broad lipolytic activity toward phosphatidylcholine, galactolipids, and triacylglycerol. These results suggest that the three sub-groups of class I acylhydrolases have specific roles in chloroplasts.     

Inhibitory profile of a LEDGF/p75 peptide against HIV-1 integrase: insight into integrase-DNA complex formation and catalysis

A lens epithelium-derived growth factor (LEDGF)/p75 peptide was evaluated for human immunodeficiency virus type 1 integrase (IN) inhibitory activity. The LEDGF/p75 peptide modestly inhibited IN catalysis and was dependent on IN-DNA assembly. The peptide was also effective at disrupting LEDGF/p75-IN complex formation. We next investigated the activity of the LEDGF/p75 peptide on IN mutant proteins that are unable to catalyze the DNA strand transfer reaction. The LEDGF/p75 peptide displayed an increased potency on these IN proteins, from 5-fold to greater than 10-fold, indicating the IN multimeric state greatly influences the peptide inhibitory effects. These results shed light on IN-DNA multimeric formation, and how this process influences the LEDGF/p75-IN interaction.     

Biphasic Effect of ATP on In Vitro Mineralization of Dental Pulp Cells

Dental pulp cells release adenosine triphosphate (ATP) in response to intrapulpal pressure and the amount released depends on the magnitude of the pressure. ATP regulates the differentiation of stem cells into adipocytes and osteoblasts. However, it is unknown whether extracellular ATP influences the stemness and osteogenic differentiation of stem cells from human exfoliated deciduous teeth (SHEDs). Therefore, this study investigated the effects of extracellular ATP at a low (0.1 μM) and high (10 μM) concentration on the stemness and osteogenic differentiation of SHEDs. Cells were cultured in either growth medium or osteogenic medium with or without 0.1–10 μM ATP. In growth medium, both concentrations of ATP increased the mRNA expression of pluripotent and osteogenic markers. In contrast, in osteogenic medium, 0.1 μM ATP enhanced in vitro mineralization, whereas 10 μM ATP inhibited this process. In addition, 10 μM ATP stimulated the mRNA expression and activity of ectonucleotide pyrophosphatase/phosphodiesterase (ENPP), an enzyme that regulates the phosphate/pyrophosphate ratio. Thus, depending on the growth condition and its concentration, ATP stimulated stemness and in vitro mineralization or inhibited mineralization. In growth medium, both ATP concentrations stimulated pluripotent and osteogenic marker gene expression. However, in osteogenic medium, a biphasic effect was found on in vitro mineralization; the low concentration stimulated, whereas the high concentration inhibited, mineralization. We propose that ATP released due to mechanical stress modulates the stemness and differentiation of SHEDs. J. Cell. Biochem. 119: 488–498, 2018. © 2017 Wiley Periodicals, Inc.