MicroRNAs (miRNAs) are an abundant class of non-coding RNAs that are believed to be important in many biological processes through regulation of gene expression. The precise molecular function of miRNAs in mammals is largely unknown and a better understanding will require loss-of-function studies in vivo. Here we show that a novel class of chemically engineered oligonucleotides, termed 'antagomirs', are efficient and specific silencers of endogenous miRNAs in mice. Intravenous administration of antagomirs against miR-16, miR-122, miR-192 and miR-194 resulted in a marked reduction of corresponding miRNA levels in liver, lung, kidney, heart, intestine, fat, skin, bone marrow, muscle, ovaries and adrenals. The silencing of endogenous miRNAs by this novel method is specific, efficient and long-lasting. The biological significance of silencing miRNAs with the use of antagomirs was studied for miR-122, an abundant liver-specific miRNA. Gene expression and bioinformatic analysis of messenger RNA from antagomir-treated animals revealed that the 3' untranslated regions of upregulated genes are strongly enriched in miR-122 recognition motifs, whereas downregulated genes are depleted in these motifs. Analysis of the functional annotation of downregulated genes specifically predicted that cholesterol biosynthesis genes would be affected by miR-122, and plasma cholesterol measurements showed reduced levels in antagomir-122-treated mice. Our findings show that antagomirs are powerful tools to silence specific miRNAs in vivo and may represent a therapeutic strategy for silencing miRNAs in disease.

https://www.gene-quantification.de/kruetzfeld-antagomirs-2005.pdf

Silencing of microRNAs in vivo with ‘antagomirs’

In the 10 years that have passed since the Nobel prize-winning discovery of RNA interference (RNAi), billions of dollars have been invested in the therapeutic application of gene silencing in humans. Today, there are promising data from ongoing clinical trials for the treatment of age-related macular degeneration and respiratory syncytial virus. Despite these early successes, however, the widespread use of RNAi therapeutics for disease prevention and treatment requires the development of clinically suitable, safe and effective drug delivery vehicles. Here, we provide an update on the progress of RNAi therapeutics and highlight novel synthetic materials for the encapsulation and intracellular delivery of nucleic acids.

Knocking down barriers: advances in siRNA delivery

Nanomaterials, such as metal or semiconductor nanoparticles and nanorods, exhibit similar dimensions to those of biomolecules, such as proteins (enzymes, antigens, antibodies) or DNA. The integration of nanoparticles, which exhibit unique electronic, photonic, and catalytic properties, with biomaterials, which display unique recognition, catalytic, and inhibition properties, yields novel hybrid nanobiomaterials of synergetic properties and functions. This review describes recent advances in the synthesis of biomolecule-nanoparticle/nanorod hybrid systems and the application of such assemblies in the generation of 2D and 3D ordered structures in solutions and on surfaces. Particular emphasis is directed to the use of biomolecule-nanoparticle (metallic or semiconductive) assemblies for bioanalytical applications and for the fabrication of bioelectronic devices.

Integrated Nanoparticle–Biomolecule Hybrid Systems: Synthesis, Properties, and Applications

Therapeutics that are designed to engage RNA interference (RNAi) pathways have the potential to provide new, major ways of imparting therapy to patients. Long, double-stranded RNAs were first shown to mediate RNAi in Caenorhabditis elegans, and the potential use of RNAi for human therapy has been demonstrated by the finding that small interfering RNAs (siRNAs; approximately 21-base-pair double-stranded RNA) can elicit RNAi in mammalian cells without producing an interferon response. We are at present conducting the first in-human phase I clinical trial involving the systemic administration of siRNA to patients with solid cancers using a targeted, nanoparticle delivery system. Here we provide evidence of inducing an RNAi mechanism of action in a human from the delivered siRNA. Tumour biopsies from melanoma patients obtained after treatment show the presence of intracellularly localized nanoparticles in amounts that correlate with dose levels of the nanoparticles administered (this is, to our knowledge, a first for systemically delivered nanoparticles of any kind). Furthermore, a reduction was found in both the specific messenger RNA (M2 subunit of ribonucleotide reductase (RRM2)) and the protein (RRM2) levels when compared to pre-dosing tissue. Most notably, we detect the presence of an mRNA fragment that demonstrates that siRNA-mediated mRNA cleavage occurs specifically at the site predicted for an RNAi mechanism from a patient who received the highest dose of the nanoparticles. Together, these data demonstrate that siRNA administered systemically to a human can produce a specific gene inhibition (reduction in mRNA and protein) by an RNAi mechanism of action.

/pdf/evidence-of-rnai-in-humans-from-systemically-administered-3pba6uirdb.pdf

Evidence of RNAi in humans from systemically administered siRNA via targeted nanoparticles

Gold colloids have fascinated scientists for over a century and are now heavily utilized in chemistry, biology, engineering, and medicine. Today these materials can be synthesized reproducibly, modified with seemingly limitless chemical functional groups, and, in certain cases, characterized with atomic-level precision. This Review highlights recent advances in the synthesis, bioconjugation, and cellular uses of gold nanoconjugates. There are now many examples of highly sensitive and selective assays based upon gold nanoconjugates. In recent years, focus has turned to therapeutic possibilities for such materials. Structures which behave as gene-regulating agents, drug carriers, imaging agents, and photoresponsive therapeutics have been developed and studied in the context of cells and many debilitating diseases. These structures are not simply chosen as alternatives to molecule-based systems, but rather for their new physical and chemical properties, which confer substantive advantages in cellular and medical applications.

/pdf/gold-nanoparticles-for-biology-and-medicine-409qkznwvh.pdf

Gold nanoparticles for biology and medicine.

A new class of bidentate bisoxazoline ligands is applied to the addition of alkynes to imines.

Application of Tartarate Derived Bidentate Bioxazolines in Enantioselective Addition of Terminal Alkynes to Imines.

Chiral Lewis bases facilitated the synthesis of highly functionalized spirooxindoles containing α-exo-methylene-γ-butyrolactones in high yields (76–92 %) and excellent enantioselectivities (up to 98 % ee) at ambient temperature.

Enantioselective Synthesis of Spirooxindole α‐exo‐Methylene‐γ‐butyrolactones from 3‐OBoc‐Oxindoles.

A tartrate derived bi(oxazoline) ligand causes remarkable asymmetric induction in the Pd-catalyzed allylation of protected oxindoles.

Palladium Catalyzed Asymmetric Allylation of 3‐OBoc‐Oxindoles: An Efficient Synthesis of 3‐Allyl‐3‐hydroxyoxindoles.

A direct, high-yielding C—H arylation at position 2 of cyclic enamides of type (I) becomes possible in the presence of CuBr as the catalyst at room temperature.

Copper(I) Bromide Catalyzed Arylation of Cyclic Enamides and Naphthyl‐1‐acetamides Using Diaryliodonium Salts.

Organocatalytic Friedel-Crafts aminoalkylation reaction is demonstrated in this study for the construction of biologically important hybrid molecular architectures of carbazole containing 3-amino oxindoles using bifunctional cinchonidine derived thiourea organocatalyst. The Friedel-Crafts functionalization of 4-hydroxy carbazole with isatin derived ketimines well performed with a wide range of substrates resulted in excellent yields (up to 95 %) and enantioselectivities (up to 99 % ee) of the desired products. A minimal catalyst loading (0.5 mol%) was utilized at ambient temperatures under mild reaction conditions. 

Venkitasamy Kesavan

Papers

Application of Tartarate Derived Bidentate Bioxazolines in Enantioselective Addition of Terminal Alkynes to Imines.

Enantioselective Synthesis of Spirooxindole α‐exo‐Methylene‐γ‐butyrolactones from 3‐OBoc‐Oxindoles.

Palladium Catalyzed Asymmetric Allylation of 3‐OBoc‐Oxindoles: An Efficient Synthesis of 3‐Allyl‐3‐hydroxyoxindoles.

Copper(I) Bromide Catalyzed Arylation of Cyclic Enamides and Naphthyl‐1‐acetamides Using Diaryliodonium Salts.

Enantioselective Synthesis of 3‐Amino‐3’‐carbazole Oxindole Derivatives via Friedel‐Crafts Aminoalkylation Reaction