Two-hit wonders: The expanding universe of multitargeting epigenetic agents

Multitargeting involves the application of molecules that are deliberately intended to bind to two or more unrelated cellular targets with high affinity. In epigenetic chemical biology and drug discovery, the rational design of multitargeting agents has evolved to a sophisticated level, and there are now five examples that have reached clinical trials. This review covers recent developments in the field and future prospects.     

Metal complexes as optical probes for DNA sensing and imaging

Transition and lanthanide metal complexes have rich photophysical properties that can be used for cellular imaging, biosensing and phototherapy. One of the applications of such luminescent compounds is the detection and visualisation of nucleic acids. In this brief review, we survey the recent literature on the use of luminescent metal complexes (including Re^I, Ru^II, Os^II, Ir^III, Pt^II, Eu^III and Tb^III) as DNA optical probes, including examples of compounds that bind selectively to non-duplex DNA topologies such as quadruplex, i-motif and DNA mismatches. We discuss the applications of metal-based luminescent complexes in cellular imaging, including time-resolved microscopy and super-resolution techniques. Their applications in biosensing and phototherapy are briefly mentioned in the relevant sections.     

Development of microsatellite markers in a clonal perennial herb,Convallaria keiskei

We developed eight polymorphic microsatellite simple sequence repeat (SSR) loci from genomic DNA of a clonal perennial herb, Convallaria keiskei, using a dual‐suppression‐polymerase chain reaction (PCR) technique and an improved technique. These markers with four to 10 alleles per locus identified 29 genotypes in 82 samples collected from a population in Hokkaido, Japan. The observed and expected heterozygosities ranged from 0.241 to 0.862 and from 0.639 to 0.825, respectively. These SSR markers will be available to identify genets and evaluate genetic diversity of C. keiskei.     

Rapid reprogramming of haemoglobin structure‐function exposes multiple dual‐antimicrobial potencies

The intrinsic cytotoxicity of cell‐free haemoglobin (Hb) has hampered the development of reliable Hb‐based blood substitutes for over seven decades. Notably, recent evidence shows that the Hb deploys this cytotoxic attack against invading microbes, albeit, through an unknown mechanism. Here, we unraveled a rapid molecular reprogramming of the Hb structure‐function triggered by virulent haemolytic pathogens that feed on the haem‐iron. On direct contact with the microbe, the Hb unveils its latent antimicrobial potency, where multiple antimicrobial fragments are released, each harbouring coordinated ‘dual‐action centres’: microbe binding and pseudoperoxidase (POX) cycle activity. The activated Hb fragments anchor onto the microbe while the juxtaposed POX instantly unleashes a localized oxidative shock, killing the pathogen‐in‐proximity. This concurrent action conceivably restricts the diffusion of free radicals. Furthermore, the host astutely protects itself from self‐cytotoxicity by simultaneously releasing endogenous antioxidants. We found that this decryption mechanism of antimicrobial potency is conserved in the ancient invertebrate respiratory protein, indicating its fundamental significance. Our definition of dual‐antimicrobial centres in the Hb provides vital clues for designing a safer Hb‐based oxygen carrier blood substitute.     

Campylobacter jejuni: Specific oligonucleotides and DNA probes for use in polymerase chain reaction-based diagnosis

Abstract A 1189 base-pair long DNA fragment, VS1, was isolated from a Campylobacter jejuni CIP 70.2 cosmid library and was found to contain regions specific for this bacterial species. For detection and identification of C. jejuni , two oligonucleotides derived from the VS1 sequence were used as primers in polymerase chain reaction test on genomic DNAs from 38 Campylobacter and from 10 non- Campylobacter strains. A specific, 358 base-pair long DNA fragment was amplified only when C. jejuni DNA was used as a target. The detection limit of the amplification reaction was as low as 1.86 fg DNA, which is the equivalent of one C. jejuni genome.     

Improved methods for targeting epigenetic reader domains of acetylated and methylated lysine

Responsible for interpreting histone post-translational modifications, epigenetic reader proteins have emerged as novel therapeutic targets for a wide range of diseases. Chemical probes have been critical in enabling target validation studies and have led to translational advances in cancer and inflammation-related pathologies. Here, we present the most recently reported probes of reader proteins that recognize acylated and methylated lysine. We will discuss challenges associated with achieving potent antagonism of reader domains and review ongoing efforts to overcome these hurdles, focusing on targeting strategies including the use of peptidomimetic ligands, allosteric modulators, and protein degraders.     

Synthetic DNA probes for the identification of sibling species in the Anopheles gambiae complex

The cloned DNA sequences pAna1, pAnq1 and pAnm14, which may be used to distinguish between at least five of the six species in the Anopheles gambiae Giles complex of Afrotropical malaria vector mosquitoes, have been sequenced. Each clone was found to possess a series of repeated sequences of 41, 30 and 163 bases respectively. In pAnq1 and pAnm14 the repeats were in direct tandem array, whilst in pAna1 the repetitive sequence was found to be interspersed by 15-17 variable bases. A comparison of a number of copies of each of the repetitive sequences within the three clones enabled the definition of the consensus sequence for each repetitive element. Based on these consensus sequences, three oligonucleotides of 21, 23 and 26 bases were derived from pAna1, pAnq1 and pAnm14 respectively. When tested as probes against DNA dot-blots and squash-blots of mosquito specimens, each oligonucleotide retained the same species-specificity as the original clones from which they were derived. The radioactively labelled oligonucleotides were able to detect as little as 5 ng of target genomic DNA in an overnight autoradiographic exposure. The synthetic DNA probes will form the basis of a simplified system for the field identification of Anopheles gambiae sibling species specimens.     

Design and synthesis of alkyl substituted pyridino[2,3-D]pyrimidine compounds as PI3Kα/mTOR dual inhibitors with improved pharmacokinetic properties and potent in vivo antitumor activity

Using pyridino[2,3-D]pyrimidine as the core, total 13 pyridino[2,3-D]pyrimidine derivatives with different alkyl substituents at C2 site have been designed and synthesized to search for novel PI3Kα/mTOR dual inhibitors. Most of the target compounds showed potent mTOR inhibition activity with IC₅₀ values ranging from single to double digit nanomole. Five target compounds exhibited pronounced PI3Kα inhibition activity. In vitro cellular assay indicated that most of the target compounds showed excellent antiproliferative activity, especially 3j whose potency against SKOV3 was 8-fold higher than the positive control AZD8055. In vitro metabolic stability study found that 3j had a comparable stability to that of AZD8055. More importantly, 3j showed better antitumor activity and pharmacokinetic properties in vivo as compared with AZD8055.