Advances in CRISPR therapeutics.

The clustered regularly interspaced short palindromic repeats (CRISPR) renaissance was catalysed by the discovery that RNA-guided prokaryotic CRISPR-associated (Cas) proteins can create targeted double-strand breaks in mammalian genomes. This finding led to the development of CRISPR systems that harness natural DNA repair mechanisms to repair deficient genes more easily and precisely than ever before. CRISPR has been used to knock out harmful mutant genes and to fix errors in coding sequences to rescue disease phenotypes in preclinical studies and in several clinical trials. However, most genetic disorders result from combinations of mutations, deletions and duplications in the coding and non-coding regions of the genome and therefore require sophisticated genome engineering strategies beyond simple gene knockout. To overcome this limitation, the toolbox of natural and engineered CRISPR-Cas systems has been dramatically expanded to include diverse tools that function in human cells for precise genome editing and epigenome engineering. The application of CRISPR technology to edit the non-coding genome, modulate gene regulation, make precise genetic changes and target infectious diseases has the potential to lead to curative therapies for many previously untreatable diseases.

Single position substitution of hairpin pyrrole-imidazole polyamides imparts distinct DNA-binding profiles across the human genome.

Pyrrole-imidazole (Py-Im) polyamides are synthetic molecules that can be rationally designed to target specific DNA sequences to both disrupt and recruit transcriptional machinery. While in vitro binding has been extensively studied, in vivo effects are often difficult to predict using current models of DNA binding. Determining the impact of genomic architecture and the local chromatin landscape on polyamide-DNA sequence specificity remains an unresolved question that impedes their effective deployment in vivo. In this report we identified polyamide-DNA interaction sites across the entire genome, by covalently crosslinking and capturing these events in the nuclei of human LNCaP cells. This technique confirms the ability of two eight ring hairpin-polyamides, with similar architectures but differing at a single ring position (Py to Im), to retain in vitro specificities and display distinct genome-wide binding profiles.

Carbocyclic Amino Ketones by Bredt's Rule-Arrested Kulinkovich-de Meijere Reaction.

The Ti(II) -mediated formation of cyclopropylamines from alkenes and amides, the Kulinkovich-de Meijere reaction, involves two carbon-carbon bond-forming steps. Strategic use of a tricyclic intermediate can arrest the process if the second step requires formation of a bridgehead double bond. Use of this Bredt's rule constraint results in the production of carbocyclic amino ketones, key alkaloid building blocks.