We report a new strategy to regulate microRNAs (miRNAs) biogenesis by using bi-functional small molecules that consist of a pre-miRNA binding unit connected by a linker to a Dicer inhibiting unit. In this effort, fluorescence polarization-based screening was used to identify neomycin as a pre-miR-21 binding ligand. Although neomycin cannot inhibit miR-21 maturation, linking it to the RNase inhibitor 1 forms the bi-functional conjugate 7A, which inhibits the production of miR-21. We expect that this strategy will be applicable to design other molecules for miRNA regulation.

Abscisic acid (ABA) was chemically modified with a photocaging group to promote photo-induced protein dimerization. This photo-controlled chemically induced dimerization (CID) method based on caged ABA enables dose-dependent light regulation of cellular processes, including transcription, protein translocation, signal transduction and cytoskeletal remodeling, without the need to perform extensive protein engineering. Caged-ABA can be easily modified to respond to different wavelengths of light. Consequently, this strategy should be applicable to the design of light-regulated protein dimerization systems and potentially be used orthogonally with other light-controlled CID systems.

An efficient one-step functionalization of FK506 by the thiol-ene click (TEC) reaction is reported. This approach, which enables rapid and quantitative generation of bioactive FK1012 and FK506 derivatives, should facilitate biomedical applications of FK506-coupled molecules and expand the scope of the TEC reaction in natural product semisynthesis.Scheme 1 Synthesis of FK506 derivatives. The general TEC condition: l eq. FK506, 1 eq. thiols and 0.05 eq. of DPAP dissolved in indicated solvents under UV (l 365 nm ) at room temperature for 15 minutes. a TEC in DCM; b TFA/DCM; c EDCI, HOBt, NEt 3 ; d TEC in MeOH/H 2 O.

A series of bifunctional molecules with different combinations of macrocyclic polyamine [12]aneN3 and coumarin moieties, 4a/b and 5a/b, were synthesized by a two-step copper(I)-mediated alkyne–azide click reactions between 1,3,5-tris(azidomethyl)benzene and Boc-protected N-propynyl-[12]aneN3/7-propynyloxycoumarins. Agarose gel electrophoresis experiments indicated that bifunctional molecules 4b and 5b effectively induced complete plasmid DNA condensation at concentrations up to 40 μM. It was found that the structural variation had a major impact on the condensation behavior of these compounds. The electrostatic interaction involving the [12]aneN3 moiety can be compensated by the binding contribution of the coumarin units during the DNA condensation process. These two types of interaction showed different effects on the reversibility of DNA condensation. Results from studies using dynamic laser scattering, atomic force microscopy, and EB replacement assay further supported the above conclusion. Cytotoxicity assays on bifunctional compounds 4a/b and 5a/b indicated their low cytotoxicity. Results from cellular uptake and cell transfection experiments proved that bifunctional compounds 4b and 5b successfully served as non-viral gene vectors. Furthermore, methyl substituents attached to the coumarin unit (4b and 5b) greatly enhanced their DNA condensation capability and gene transfection. These bifunctional molecules, with the advantages of lower cytotoxicity, good water solubility, and potential structural modification, will have great potential for the development of new non-viral gene delivery agents.