CRISPR-Cas12a Possesses Unconventional DNase Activity that Can Be Inactivated by Synthetic Oligonucleotides.

CRISPR-Cas12a (CRISPR-Cpf1) was reported to have multiple types of cleavage activities. Without the assistance of CRISPR RNA (crRNA), we investigated DNase activity and substrate specificity of Cas12a orthologs in the presence of diverse divalent metal ions. Cas12a from different species are capable of degrading single-stranded DNA (ssDNA) and/or double-stranded DNA (dsDNA), depending on the metal ions used. In spite of sharing high sequence similarity and functional domains among diverse Cas12a orthologs, only Acidaminococcus sp. Cas12a (AsCas12a) showed a predominant preference for cleaving ssDNA, but no detectable activity toward dsDNA substrate in the presence of magnesium (II) ions. In addition, we found that both AsCas12a and Francisella novicida Cas12a (FnCas12a) caused substantial dsDNA cleavage in the presence of manganese (II) ion. More importantly, the DNase activities can be inhibited by synthetic DNA oligonucleotides with phosphorothioate linkage modifications. Overall, ssDNase activity of the Cas12a orthologs uncovered a distinct approach for DNA cleavage compared with crRNA-guided dsDNA breaks, and provided insights into potential biological and therapeutic applications.

DYZ-2-90, a novel neo-tanshinlactone ring-opened compound, induces ERK-mediated mitotic arrest and subsequent apoptosis by activating JNK in human colorectal cancer cells.

Over the past several decades, there has been a considerable and still growing interest in discovering natural products with anticancer potential from traditional Chinese medicine and increasing their anticancer selectivity by chemical modification. In addition, total synthesis of active compounds from natural products can overcome problems related to poor resource availability. DYZ-2-90 is a novel ring-opened compound modified from neo-tanshinlactone, which is isolated from Chinese medicinal herb tanshen. Both in vitro and in vivo tubulin polymerization assays showed that DYZ-2-90 directly bound to microtubules and rapidly induced tubulin depolymerization, inducing ERK-mediated mitotic arrest and subsequent apoptosis by JNK activation in cancer cells, respectively. These results suggest that the fate of cells that undergo mitotic arrest is dictated by two competing networks activated by DYZ-2-90: the cytoprotective ERK pathway and the stress-related JNK pathway. DYZ-2-90 is therefore a novel microtubule-destabilizing agent and a new drug candidate for cancer therapy. This paper provides a new insight into the model of mitotic cell death, which was proposed in order to elucidate how cancer cells respond to microtubule-interfering agents and prolonged cell cycle delay.

Recent Progress of Research on Herbal Products Used in Traditional Chinese Medicine: the Herbs belonging to The Divine Husbandman's Herbal Foundation Canon ( Shén Nóng Ben Cǎo Jing).

This article will review selected herbal products from Chinese Materia Medica that are used in Traditional Chinese Medicine. The herbs come from the upper, middle, and lower class medicines as listed in The Divine Husbandman's Herbal Foundation Canon ( Shén Nóng Ben Cǎo Jing). The review will focus on the active constituents of the herbs and their bioactivities, with emphasis on the most recent progress in research for the period of 2003 to 2011.

Biosynthesis, total syntheses, and antitumor activity of tanshinones and their analogs as potential therapeutic agents.

Tanshinones are a series of abietane diterpenes, isolated exclusively from Salvia miltiorrhiza and related species. More than 40 tanshinones and their analogs have been isolated since the 1930s. Their biosynthetic pathway correlates with the MEP/DOXP pathway, and many key enzymes, such as mCPS, are responsible for establishing their molecular scaffolds and stereospecificity. Because of their unique structural characteristics and promising biological activities, total syntheses of various tanshinones have attracted the interest of many synthetic chemists, including R. H. Thomson, H. Kakisawa, R. L. Danheiser, Y. Inouye and J. K. Snyder. Tanshinones and their analogs exhibit interesting and broad antitumor activity in various cell and animal models. Most recently, the tanshinone analog neo-tanshinlactone has shown potent and selective activity against breast cancer. This review will discuss the biosynthesis, total syntheses, and antitumor activities of tanshinones,especially neo-tanshinlactone and its analogs.