Besides cell penetrating peptides, non-viral methods of gene delivery to neuronal cells include nano-particles, lipids and cationic polymers. method can be used for acute models of neuro-degeneration through the perturbation of miRNAs. Keywords: Neuroscience, Issue 106, microRNA, brain specific delivery, behaviour, mouse footprint assay, neurotropic peptide, ataxia, Locked Nucleic Acidity (LNA), RVG Download video stream. == Introduction == MicroRNAs have emerged because novel therapeutic targets due to their universal role in the regulation of gene expression and direct evidence intended for involvement in disease. MiRNAs are being actively explored for their potential as drug targets1, 2 . Further, alterations in miRNA expression are associated with several diseases3and simulation of these changes by artificial perturbation of miRNA expression can be used to study the cellular pathways involved in disease manifestation. Tissue Acrizanib specific delivery of miRNA focusing on drugs is currently a major challenge for miRNA based drug development. Acrizanib Antagomirs and miRNA mimics are promising brokers for perturbing miRNA levels46. However , special features that enhance their specificity and efficacy have to be incorporated into the design of antagomirs before they can be used forin vivoperturbation of miRNA expression. MicroRNAs are especially relevant as focuses on in currently incurable neurodegenerative and neuro-developmental diseases. The blood-brain barrier poses a restriction Acrizanib to the delivery of antagomirs in the brain. Stereotactic injections are widely used in rodent models to deliver molecules to specific locations in the brain7. It requires skill, extensive investment in instrumentation and time. Stereotactic injections are invasive, involve surgical treatment, cause at least small injury and are restricted to local delivery. The use of cell penetrating peptides with a preference intended for targeting neurons can counter-top these limitations since they can be delivered through the trans-vascular route but breach the blood brain barrier. Such a peptide derived from the Rabies Virus Glycoprotein (RVG), was previously used to deliver siRNA against Japanese Encephalitis Virus in mice8. We found that using the peptide for antagomir delivery, miRNAs can be effectively knocked down in the mouse brain9. The second major challenge of miRNA knock-down arises from the small size of miRNAs and the presence of closely related sequence isoforms. We take the example of mmu-miR-29 family which consists of three closely related isoforms, miR-29a, b and c. Antagomirs are also generally modified along the backbone to increase their stability and render them resistant to attack by nucleases. Locked Nucleic Acids (LNAs) offer a further advantage that they enhance thermal stability and even lead to target degradation over and past steric hindrance10. Introducing modifications all along the backbone can be effective but expensive. We have earlier seen that modifications beyond an optimal number may not further enhance the efficacy. The design of the antagomir therefore involves the optimal modification from the antagomir. To complex the antagomir non-covalently with the neurotropic peptide, a charged hepta- to nona-arginine extension is used. D-Arginine residues are used since they confer higher stability as they are not susceptible to cleavage by proteases. Hepta- to nona-arginine stretches work as efficient cell penetrating brokers, although they do not confer cell type specificity. By covalently linking the RVG peptide to the nona-arginine linker, a neurotropic, cell penetrating peptide was generated. The positively charged residues of the peptide interact with the negatively charged nucleic acidity backbone, to form complexes. These complexes can be used to effectively transfect DNA or RNA into cultured cells andin vivointo tissues. == Protocol == Note: All Rabbit Polyclonal to PLA2G4C the procedure including animal topics have been approved by Institutional Animals Ethics Committee (IAEC) at the Institute of Genomics and Integrative Biology, New Delhi (IGIB/AEC/10/2013). This protocol is specifically adjusted for targeted delivery of Antagomir-29 in the brain and knockdown of miR-29. == 1 . Antagomir Design Strategy == Retrieve the adult miRNA sequence from miRBase11(http://www.mirbase.org/). Retrieve the sequences of related miRNA family members using the Gene Family link in the miRBase record (http://www.mirbase.org/cgi-bin/mirna_summary.pl?fam=MIPF0000009). Reverse complement the sequence: http://www.bioinformatics.org/sms/rev_comp.htmlprovides a convenient tool to reverse enhance sequences. == 2 . Antagomir-neuropeptide Complex Preparation == Note: This is the most critical step in the protocol and it needs standardization. To standardize the protocol any fluorescently.