We thank Souvik Maiti for help in designing the antagomirs. We also acknowledge Rangeetha J. Naik, Rakesh Dey, and Bijay Pattnaik for their help with experimental methods. This work was funded by the Council of Scientific and Industrial Research (BSC0123). HS, MV and RR acknowledge fellowship from the Council of Scientific and Industrial Research, India. MAS acknowledge fellowship from the University Grants Commission, India.

Note: All the procedure including animal subjects 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
<ol>
	<li>Retrieve the mature miRNA sequence from miRBase11 (<a href="http://www.mirbase.org/">http://www.mirbase.org/</a>).</li>
	<li>Retrieve the sequences of related miRNA family members using the &#8220;Gene Family&#8221; link in the miRBase record 
	(<a href="http://www.mirbase.org/cgi-bin/mirna_summary.pl?fam=MIPF0000009">http://www.mirbase.org/cgi-bin/mirna_summary.pl?fam=MIPF0000009</a> ).</li>
	<li>Reverse complement the sequence: <a href="http://www.bioinformatics.org/sms/rev_comp.html">http://www.bioinformatics.org/sms/rev_comp.html</a> provides a convenient tool to reverse complement sequences.</li>
	<li>Mark the positions to be modified by LNA using the following guidelines:
	<ol>
		<li>Choose Thymine residues placed 3-4 bases apart for the LNA modification, since LNA pyrimidines are more stable than purines12.</li>
		<li>Choose Cytosine residues separated by 3-4 residues if previous step produces less than five modifications.</li>
		<li>Prioritize the five modifications to the 5&#8217; end of the antagomir, since this avoids the seed sequence.</li>
	</ol>
	</li>
</ol>
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 labeled oligonucleotide (FLO) can be used in place of the antagomir9. The peptides should be of high purity (HPLC grade, 98% purity).Sequences and charge of peptide and antagomir are given in Table 1.
<ol>
	<li>Decide the number of moles of antagomir to be injected based on molar charge on antagomir, its toxicity and weight of the mouse. Calculate the number of moles of peptide to be injected based on molar charge ratio of antagomir : peptide. 
	NOTE: Standardize molar charge ratio of antagomir : peptide for toxicity and effective delivery in the mouse brain. Use different molar charge ratios of fluorescently labeled oligonucleotide: peptide for standardization. We found that Antagomir-29 and control were both toxic at 4microgram/gram body weight of mouse.&#160; Antagomir-29 and control were used at 2microgram/gram body weight, but this effective concentration is likely to vary for each microRNA.</li>
	<li>Dilute the peptide and antagomir in separate microfuge tubes from stock solutions with sterile 10% D-glucose to the desired final concentration as calculated in step 1.</li>
	<li>Keep the microfuge tube with the peptide solution on a vortex at moderate vortexing speed.</li>
	<li>Add 1/3rd of the antagomir solution to the peptide solution tube, slowly, drop wise, while it is mixed thoroughly on a vortex mixer.</li>
	<li>Continue mixing of solutions on the vortex for next 1 min and then allow the mixture to stand for 1 min.</li>
	<li>Repeat the step 4 and 5 two more times to mix the remaining antagomir solution with the peptide solution in the same microfuge tube. The slow addition is critical for the formation of mono-disperse complexes that are effective in transfection. Rapid addition can lead to aggregation of the complexes and their precipitation.</li>
	<li>Incubate the complex for 30 min at RT without vortexing. During this time of&#160;&#160;&#160; incubation, acclimatize the mice to the lab where injections will be performed.</li>
</ol>
3. Tail Vein Injection of Antagomir-neuropeptide Complex
<ol>
	<li>To restrain the animal, place the mouse in a restrainer or decapicone of proper size.</li>
	<li>Clean the surface of the tail using cotton swab pre-soaked in warm water (about 40&#176;C). This will promote vasodilation and increase the visibility of the vein.</li>
	<li>Approach the tail with a small volume (0.5 &#8211; 1.0 cc) insulin syringe at a 15-20&#176; angle. Be careful not to introduce any air into the syringe. Start at the distal portion of the tail. Inject the complex. Remove the needle and apply an antiseptic swab directly to the injection site (approximately 5-10 sec) to stop any bleeding.</li>
	<li>Replace the mouse in an individually ventilated cage in the group of 3-5, with the corncob and tissue paper as enrichment. Do not keep uninjected and injected mice in same cage.</li>
</ol>
4. Behavioural Assays
Note: Keep the time interval of 3-4 hr in between injection and behavioural assays to allow recovery after injection. Bring the mouse to a quiet room.&#160; Do not disturb the animals during this period of acclimatization.
<ol>
	<li>Acclimatize the mouse to the new room for 30 min and then start the following behavioural assays. Keep a gap of 10 min in between each behavioural assay.</li>
	<li>Hindlimb clasping: 
	NOTE: This test indicates motor dysfunction and neurological impairment.
	<ol>
		<li>Lift the mouse gently by holding near base of the tail in the clear background.</li>
		<li>Check the hindlimb position for 10-15 sec. Wild type mouse splays hindlimbs away from abdomen, while an ataxic mouse tends to retract one or both hindlimbs towards the abdomen more than 50% of time suspended13.</li>
		<li>Return the mouse to the cage</li>
	</ol>
	</li>
	<li>Ledge test:
	<ol>
		<li>Lift the mouse gently by holding the tail and keep it on the ledge of a cage.</li>
		<li>Observe the mouse specifically at the corner of the cage. Wild type mouse can pass the corners easily without fear and losing the balance. Ataxic mouse lose its balance, freeze or shakes while walking along the cage ledge and at the corners.</li>
	</ol>
	</li>
	<li>Mouse foot print assay: 
	NOTE: For this assay keep the absorbent sheet ready, on the floor of a narrow runway (~70-cm-long, ~5-cm-wide with ~5-cm-high walls.)
	<ol>
		<li>Hold the mouse gently by one hand and apply ink on the hind limbs by a brush.</li>
		<li>Place the absorbent sheet on the floor of a narrow runway.</li>
		<li>Allow mouse to walk or run over an absorbent sheet in a straight line in a runway from one end to other.</li>
		<li>Repeat the process two more times with each mouse using fresh absorbent sheet.</li>
		<li>Measure the distance between two consecutive steps in the forward movement. Do not include first and last few footprints where the animal is just initiating and finishing its run, respectively.</li>
	</ol>
	</li>
</ol>

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	<li>Roshan, R., Ghosh, T., Scaria, V., Pillai, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MicroRNAs:+novel+therapeutic+targets+in+neurodegenerative+diseases.">MicroRNAs: novel therapeutic targets in neurodegenerative diseases.</a> Drug discovery today. 14, 1123-1129 (2009).</li><li>Maes, O. C., Chertkow, H. M., Wang, E., Schipper, H. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MicroRNA:+Implications+for+Alzheimer+Disease+and+other+Human+CNS+Disorders.">MicroRNA: Implications for Alzheimer Disease and other Human CNS Disorders.</a> Current Genomics. 10, 154-168 (2009).</li><li>Soifer, H. S., Rossi, J. 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The authors have nothing to disclose.

Here we demonstrate a widely accessible methodology to study the effects of miRNA modulation. Currently, most attempts at in vivo characterization of miRNA functions involve the creation of knockout mice or a transgenic that expresses a miRNA sponge. Most miRNAs, even the cell type specific ones are expressed in more than one organ. For instance, miRNAs initially thought to be specific to the hematopoietic system are also expressed in the brain, due to the presence of microglia. Thus even a cell type specifi...

MicroRNAs have emerged as novel therapeutic targets due to their universal role in the regulation of gene expression and direct evidence 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 diseases3 and simulation of these changes by artificial perturbation of miRNA expression can be used to study the cellular pathways involved in disease manifestation. Tissue specific delivery of miRNA targeting drugs is currently a major challenge for miRNA based drug development. Antagomirs and miRNA mimics are promising agents for perturbing miRNA levels4&#8211;6. However, special features that enhance their specificity and efficacy have to be incorporated into the design of antagomirs before they can be used for in vivo perturbation of miRNA expression.
MicroRNAs are especially relevant as targets in currently incurable neurodegenerative and neuro-developmental diseases. The blood-brain barrier poses a restriction 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 surgery, cause at least minor injury and are restricted to local delivery. The use of cell penetrating peptides with a preference for targeting neurons can counter 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 beyond 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 of 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 act as efficient cell penetrating agents, 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 acid backbone, to form complexes. These complexes can be used to effectively transfect DNA or RNA into cultured cells and in vivo into tissues.

<table><tbody><tr><td>Vortex</td><td></td><td></td><td></td></tr><tr><td>Restrainer or Decapicone</td><td></td><td></td><td></td></tr><tr><td>Narrow runway</td><td></td><td></td><td>~70-cm-long, ~5-cm-wide with ~5-cm-high walls.</td></tr><tr><td>Reagents</td><td></td><td></td><td></td></tr><tr><td>Fluorescently labelled oligonucleotides (siGLO)</td><td>GE Healthcare Dharmacon INC</td><td>D0016300120</td><td></td></tr><tr><td>10% sterile D-glucose</td><td></td><td></td><td></td></tr><tr><td>Antagomir-29</td><td>Exiqon</td><td>custom synthesis</td><td></td></tr><tr><td>Antagomir-control</td><td>Exiqon</td><td>custom synthesis</td><td></td></tr><tr><td>Neuropeptide RVG</td><td>G.L.Biochem (Shanghai) Ltd.</td><td>custom synthesis</td><td>&gt;98% purity</td></tr><tr><td>Neuropeptide RVM</td><td>G.L.Biochem (Shanghai) Ltd.</td><td>custom synthesis</td><td>&gt;98% purity</td></tr><tr><td>Other</td><td></td><td></td><td></td></tr><tr><td>Cotton</td><td></td><td></td><td></td></tr><tr><td>Warm water</td><td></td><td></td><td></td></tr><tr><td>Insulin syringes</td><td></td><td></td><td></td></tr><tr><td>Absorbent sheets</td><td></td><td></td><td></td></tr><tr><td>Ink</td><td></td><td></td><td></td></tr><tr><td>Brush</td><td></td><td></td><td></td></tr><tr><td>Antiseptic</td><td></td><td></td><td></td></tr></tbody></table>

a simple alternative to stereotactic injection for brain specific knockdown of mirna

MicroRNAs (miRNAs) are key regulators of gene expression. In the brain, vital processes like neurodevelopment and neuronal functions depend on the correct expression of microRNAs. Perturbation of microRNAs in the brain can be used to model neurodegenerative diseases by modulating neuronal cell death. Currently, stereotactic injection is used to deliver miRNA knockdown agents to specific location in the brain. Here, we discuss strategies to design antagomirs against miRNA with locked nucleotide modifications (LNA). Subsequently describe a method for brain specific delivery of antagomirs, uniformly across different regions of the brain. This method is simple and widely applicable since it overcomes the surgery, associated injury and limitation of local delivery in stereotactic injections. We prepared a complex of neurotropic, cell-penetrating peptide Rabies Virus Glycoprotein (RVG) with antagomir against miRNA-29 and injected through tail vein, to specifically deliver in the brain. The antagomir design incorporated features that allow specific targeting of the miRNA and formation of non-covalent complexes with the peptide. The knock-down of the miRNA in neuronal cells, resulted in apoptotic cell death and associated behavioural defects. Thus, the method can be used for acute models of neuro-degeneration through the perturbation of miRNAs.

Using the procedure presented here, complexes of 50microgram fluorescently labeled oligonucleotide (FLO) and ~850microgram RVG peptide of 1:15 molar charge ratio (FLO : peptide) were prepared and injected only once through tail vein. Complex of non-neurotropic Rabies Virus Matrix (RVM) peptide and FLO was used as a delivery control. Next day, mice brain and liver were isolated and single cell suspensions were prepared. Cells were observed under microscope for green fluorescence. FLO-RVG complex was successfully delivered...

Watch this Scientific Journal Video about A Simple Alternative to Stereotactic Injection for Brain Specific Knockdown of miRNA at JoVE.com

A Simple Alternative to Stereotactic Injection for Brain Specific Knockdown of miRNA

MicroRNAs play crucial roles in the brain and are potential targets for modeling neuro-degeneration. However, perturbing miRNA levels is challenging due to the short length of miRNA and inaccessibility of the brain tissue. This video presents a method for antagomir design and brain specific delivery using a neuropeptide in mice.

MicroRNAs (miRNAs) are key regulators of gene expression.  In the brain, vital processes like neurodevelopment and neuronal functions depend on the ...

a-simple-alternative-to-stereotactic-injection-for-brain-specific

Research

JoVE Journal

Neuroscience

12.6K Views.  CSIR-Institute of Genomics and Integrative Biology, New Delhi, India. MicroRNAs play crucial roles in the brain and are potential targets for modeling neuro-degeneration. However, perturbing miRNA levels is challenging due to the short length of miRNA and inaccessibility of the brain tissue. This video presents a method for antagomir design and brain specific delivery using a neuropeptide in mice.

Video: A Simple Alternative to Stereotactic Injection for Brain Specific Knockdown of miRNA

Stereotactic Injection of MicroRNA-expressing Lentiviruses to the Mouse Hippocampus CA1 Region and Assessment of the Behavioral Outcome

MicroRNAs (miRNAs) are small regulatory single-stranded RNA molecules around 22 nucleotides long that may each target numerous mRNA transcripts and dim an entire gene expression pathway by inducing destruction and/or inhibiting translation of these targets. Several miRNAs play key roles in maintaining neuronal structure and function and in higher-level brain functions, and methods are sought for manipulating their levels for exploring these functions. Here, we present a direct in vivo method for examining the cognitive consequences of enforced miRNAs excess in mice by stereotactic injection of miRNA-encoding virus particles. Specifically, the current protocol involves injection into the hippocampal CA1 region, which contributes to mammalian memory consolidation, learning, and stress responses, and offers a convenient injection site. The coordinates are measured according to the mouse bregma and virus perfusion is digitally controlled and kept very slow. After injection, the surgery wound is sealed and the animals recover. Lentiviruses encoding silencers of the corresponding mRNA targets serve to implicate the specific miRNA/target interaction responsible for the observed effect, with na&iuml;ve mice, mice injected with saline and mice injected with "empty" lentivirus vectors as controls. One month post-injection, the animals are examined in the Morris Water Maze (MWM) for assessing their navigation learning and memory abilities. The MWM is a round tank filled with colored water with a small platform submerged 1 cm below the water surface. Steady visual cues around the tank allow for spatial navigation (sound and the earth's magnetic field may also assist the animals in navigating). Video camera monitoring enables measuring the route of swim and the time to find and amount the platform. The mouse is first taught that mounting the hidden platform offers an escape from the enforced swimming; it is then tested for using this escape and finally, the platform is removed and probe tests examine if the mouse remembers its previous location. Repeated tests over several consecutive days highlight improved performance of tested mice at shorter latencies to find and mount the platform, and as more direct routes to reach the platform or its location. Failure to show such improvement represents impaired learning and memory and/or anxiety, which may then be tested specifically (e.g. in the elevated plus maze). This approach enables validation of specific miRNAs and target transcripts in the studied cognitive and/or stress-related processes.

MicroRNAs have significant roles in brain structure and function. Here we describe a method to enforce hippocampal miRNA over-expression using stereotactic injection of an engineered miRNA-expressing lentivirus. This approach can serve as a relatively rapid way to assess the in vivo effects of over-expressed miRNAs in specific brain regions.

MicroRNAs (miRNAs) are small regulatory single-stranded RNA molecules around 22 nucleotides long that may each target numerous mRNA transcripts and dim an ...

Behavior

Systemic Delivery of MicroRNA Using Recombinant Adeno-associated Virus Serotype 9 to Treat Neuromuscular Diseases in Rodents

RNA interference via the endogenous miRNA pathway regulates gene expression by controlling protein synthesis through post-transcriptional gene silencing. In recent years, miRNA-mediated gene regulation has shown potential for treatment of neurological disorders caused by a toxic gain of function mechanism. However, efficient delivery to target tissues has limited its application. Here we used a transgenic mouse model for spinal and bulbar muscular atrophy (SBMA), a neuromuscular disease caused by polyglutamine expansion in the androgen receptor (AR), to test gene silencing by a newly identified AR-targeting miRNA, miR-298. We overexpressed miR-298 using a recombinant adeno-associated virus (rAAV) serotype 9 vector to facilitate transduction of non-dividing cells. A single tail-vein injection in SBMA mice induced sustained and widespread overexpression of miR-298 in skeletal muscle and motor neurons and resulted in amelioration of the neuromuscular phenotype in the mice.

Here we describe the delivery of microRNA using a recombinant adeno-associated virus serotype 9 in a mouse model of a neuromuscular disease. A single peripheral administration in mice resulted in sustained miRNA overexpression in muscle and motor neurons, providing an opportunity to study miRNA function and therapeutic potential in vivo.

RNA interference via the endogenous miRNA pathway regulates gene expression by controlling protein synthesis through post-transcriptional gene silencing. ...

Genetics

In Vivo Inhibition of MicroRNA to Decrease Tumor Growth in Mice

MicroRNAs (miRNAs) are important regulators of gene expression through their ability to destabilize mRNA and inhibit translation of target mRNAs. An ever-increasing number of studies have identified miRNAs as potential biomarkers for cancer diagnosis and prognosis, and also as therapeutic targets, adding an extra dimension to cancer evaluation and treatment. In the context of thyroid cancer, tumorigenesis results not only from mutations in important genes, but also from the overexpression of many miRNAs. Accordingly, the role of miRNAs in the control of thyroid gene expression is evolving as an important mechanism in cancer. Herein, we present a protocol to examine the effects of miRNA-inhibitor delivery as a therapeutic modality in thyroid cancer using human tumor xenograft and orthotopic mouse models. After engineering stable thyroid tumoral cells expressing GFP and luciferase, cells are injected into nude mice to develop tumors, which can be followed by bioluminescence. The in vivo inhibition of a miRNA can reduce tumor growth and upregulate miRNA gene targets. This method can be used to assess the importance of a determined miRNA in vivo, in addition to identifying new therapeutic targets.

This protocol describes xenograft and orthotopic mouse models of human thyroid tumorigenesis as a platform to test microRNA-based inhibitor treatments. This approach is ideal to study the function of non-coding RNAs and their potential as new therapeutic targets.

MicroRNAs (miRNAs) are important regulators of gene expression through their ability to destabilize mRNA and inhibit translation of target mRNAs. An ...

Cancer Research

Characterization of Functionally Associated miRNAs in Glioblastoma and their Engineering into Artificial Clusters for Gene Therapy

The biological relevance of microRNAs (miRNAs) in health and disease significantly relies on specific combinations of many simultaneously deregulated miRNAs rather than the action of a single miRNA. The characterization of these specific miRNAs modules is a fundamental step in maximizing their use in therapy. This is extremely relevant because their combinatorial attributes can be practically exploited. Described here is a method to define a specific miRNA signature relevant to the control of oncogenic chromatin repressors in glioblastoma. The approach first defines a general group of miRNAs that are deregulated in tumors in comparison to normal tissue. The analysis is further refined by differential culture conditions, underscoring a subgroup of miRNAs that are co-expressed simultaneously during specific cellular states. Finally, the miRNAs that satisfy these filters are combined into an artificial polycistronic transgenes, which is based on a scaffold of naturally existing miRNA clusters genes, then used for overexpression of these miRNA modules into receiving cells.

Described here is a protocol for characterizing modules of biologically synergistic miRNAs and their assembly into short transgenes, which allows simultaneous overexpression for gene therapy applications.

The biological relevance of microRNAs (miRNAs) in health and disease significantly relies on specific combinations of many simultaneously deregulated ...

In ovo Electroporation of miRNA-based Plasmids in the Developing Neural Tube and Assessment of Phenotypes by DiI Injection in Open-book Preparations

Commissural dI1 neurons have been extensively studied to elucidate the mechanisms underlying axon guidance during development1,2. These neurons are located in the dorsal spinal cord and send their axons along stereotyped trajectories. Commissural axons initially project ventrally towards and then across the floorplate. After crossing the midline, these axons make a sharp rostral turn and project longitudinally towards the brain. Each of these steps is regulated by the coordinated activities of attractive and repulsive guidance cues. The correct interpretation of these cues is crucial to the guidance of axons along their demarcated pathway. Thus, the physiological contribution of a particular molecule to commissural axon guidance is ideally investigated in the context of the living embryo. Accordingly, gene knockdown in vivo must be precisely controlled in order to carefully distinguish axon guidance activities of genes that may play multiple roles during development.
Here, we describe a method to knockdown gene expression in the chicken neural tube in a cell type-specific, traceable manner. We use novel plasmid vectors3 harboring cell type-specific promoters/enhancers that drive the expression of a fluorescent protein marker, followed directly by a miR30-RNAi transcript4 (located within the 3'-UTR of the cDNA encoding the fluorescent protein) (Figure 1). When electroporated into the developing neural tube, these vectors elicit efficient downregulation of gene expression and express bright fluorescent marker proteins to enable direct tracing of the cells experiencing knockdown3. Mixing different RNAi vectors prior to electroporation allows the simultaneous knockdown of two or more genes in independent regions of the spinal cord. This permits complex cellular and molecular interactions to be examined during development, in a manner that is fast, simple, precise and inexpensive. In combination with DiI tracing of commissural axon trajectories in open-book preparations5, this method is a useful tool for in vivo studies of the cellular and molecular mechanisms of commissural axon growth and guidance. In principle, any promoter/enhancer could be used, potentially making the technique more widely applicable for in vivo studies of gene function during development6.
This video first demonstrates how to handle and window eggs, the injection of DNA plasmids into the neural tube and the electroporation procedure. To investigate commissural axon guidance, the spinal cord is removed from the embryo as an open-book preparation, fixed, and injected with DiI to enable axon pathways to be traced. The spinal cord is mounted between coverslips and visualized using confocal microscopy.

In ovo Electroporation of miRNA-based Plasmids in the Developing Neural Tube and Assessment of Phenotypes by DiI Injection in Open-book Preparations

A method by which gene expression in the neural tube can be downregulated in a cell type-specific, traceable manner is described. We demonstrate how in ovo electroporation of microRNA-based plasmids that elicit spatiotemporally controlled RNA interference can be used to investigate commissural axon guidance in the developing neural tube.

Commissural dI1 neurons have been extensively studied to elucidate the mechanisms underlying axon guidance during development1,2. These neurons are ...

A Positioning Device for the Placement of Mice During Intranasal siRNA Delivery to the Central Nervous System

Intranasal (IN) drug delivery to the brain has emerged as a promising method to bypass the blood-brain barrier (BBB) for the delivery of drugs into the central nervous system (CNS). Recent studies demonstrate the use of a peptide, RVG9R, incorporating the minimal receptor-binding domain of the Rabies virus glycoprotein, in eliciting the delivery of siRNA into neurons in the brain. In this protocol, the peptide-siRNA formulation is delivered intranasally with a pipette in the dominant hand, while the anesthetized mouse is restrained by the scruff with the nondominant hand in a "head down-and-forward position" to avoid drainage into the lung and stomach upon inhalation. This precise gripping of mice can be learned but is not easy and requires practice and skill to result in effective CNS uptake. Furthermore, the process is long-drawn, requiring about 45 min for the administration of a total volume of ~20-30 &#181;L of solution in 1-2 &#181;L droplet volumes per inhalation, with 3-4 min rest periods between each inhalation. The objective of this study is to disclose a mouse positioning device that enables the appropriate placement of mice for efficient IN administration of the peptide-siRNA formulation. Multiple features are incorporated into the design of the device, such as four or eight positioning chairs with adjustable height and tilt to restrain anesthetized mice in the head down-and-forward position, enabling easy visualization of the mice's nares and a built-in heating pad to maintain the mice's body temperatures during the procedure. Importantly, the ability to treat four or eight mice simultaneously with RVG9R-siRNA complexes in this manner enables studies on a much quicker time scale, for the testing of an IN therapeutic siRNA approach. In conclusion, this device allows for appropriate and controlled mouse head positioning for IN application of RVG9R-siRNA and other therapeutic molecules, such as nanoparticles or antibodies, for CNS delivery.

Here, we present a protocol using a mouse positioning device that enables the appropriate placement of mice for the intranasal administration of a brain-targeting peptide-siRNA formulation enabling effective gene silencing in the central nervous system.

Intranasal (IN) drug delivery to the brain has emerged as a promising method to bypass the blood-brain barrier (BBB) for the delivery of drugs into the ...

Immunology and Infection

Combining Optogenetics with Artificial microRNAs to Characterize the Effects of Gene Knockdown on Presynaptic Function within Intact Neuronal Circuits

The purpose of this protocol is to characterize the effect of gene knockdown on presynaptic function within intact neuronal circuits. We describe a workflow on how to combine artificial microRNA (miR)-mediated RNA interference with optogenetics to achieve selective stimulation of manipulated presynaptic boutons in acute brain slices. The experimental approach involves the use of a single viral construct and a single neuron-specific promoter to drive the expression of both an optogenetic probe and artificial miR(s) against presynaptic gene(s). When stereotactically injected in the brain region of interest, the expressed construct makes it possible to stimulate with light exclusively the neurons with reduced expression of the gene(s) under investigation. This strategy does not require the development and maintenance of genetically modified mouse lines and can in principle be applied to other organisms and to any neuronal gene of choice. We have recently applied it to investigate how the knockdown of alternative splice isoforms of presynaptic P/Q-type voltage-gated calcium channels (VGCCs) regulates short-term synaptic plasticity at CA3 to CA1 excitatory synapses in acute hippocampal slices. A similar approach could also be used to manipulate and probe the neuronal circuitry in vivo.

This protocol provides a workflow on how to combine artificial microRNA-mediated RNA interference with optogenetics to stimulate specifically presynaptic boutons with reduced expression of selective gene(s) within intact neuronal circuits.

The purpose of this protocol is to characterize the effect of gene knockdown on presynaptic function within intact neuronal circuits. We describe a ...

Loss-of-Function Approach in the Embryonic Chick Retina by Using Tol2 Transposon-Mediated Transgenic Expression of Artificial microRNAs

The chick retina has long been an important model system in developmental neurobiology, with advantages including its large size, rapid development, and accessibility for visualization and experimental manipulations. However, its major technical limitation had been the lack of robust loss-of-function approaches for gene function analyses. This protocol describes a methodology of gene silencing in the developing chick retina that involves transgenic expression of artificial microRNAs (miRNAs) by using the Tol2 transposon system. In this approach, a Tol2 transposon plasmid that contains an expression cassette for the EmGFP (emerald green fluorescent protein) marker and artificial pre-miRNA sequences against a target gene is introduced into the embryonic chick retina with a Tol2 transposase expression construct by in ovo electroporation. In the transfected retinal cells, the transposase catalyzes the excision of the expression cassette from the transposon vector and its integration into host chromosomes, leading to the stable expression of miRNAs and the EmGFP protein. In our previous study, we have demonstrated that the expression of Nel, a glycoprotein that exerts multiple functions in neural development, can be significantly suppressed in the developing chick retina by using this technique. Our results indicate that this methodology induces a stable and robust suppression of gene expression and thus provides an efficient loss-of-function approach for studies of retinal development.

We have developed a novel loss-of-function approach that involves the introduction and genomic integration of artificial micro-RNA sequences into chick embryos by using in ovo electroporation and the Tol2 transposon system. This technique provides a robust and stable gene knockdown methodology for studies of gene function during development.

The chick retina has long been an important model system in developmental neurobiology, with advantages including its large size, rapid development, and ...

In Vivo Nanovector Delivery of a Heart-specific MicroRNA-sponge

MicroRNA (miRNA) is small non-coding RNA which inhibits post-transcriptional messenger RNA (mRNA) expression. Human diseases, such as cancer and cardiovascular disease, have been shown to activate tissue and/or cell-specific miRNA expression associated with disease progression. The inhibition of miRNA expression offers the potential for a therapeutic intervention. However, traditional approaches to inhibit miRNAs, employing antagomir oligonucleotides, affect specific miRNA functions upon global delivery. Herein, we present a protocol for the in vivo cardio-specific inhibition of the miR-181 family in a rat model. A miRNA-sponge construct is designed to include 10 repeated anti-miR-181 binding sequences. The cardio-specific &#945;-MHC promoter is cloned into the pEGFP backbone to drive the cardio-specific miR-181 miRNA-sponge expression. To create a stable cell line expressing the miR-181-sponge, myoblast H9c2 cells are transfected with the &#945;-MHC-EGFP-miR-181-sponge construct and sorted by fluorescence-activated cell sorting (FACs) into GFP positive H9c2 cells which are cultured with neomycin (G418). Following stable growth in neomycin, monoclonal cell populations are established by additional FACs and single cell cloning. The resulting myoblast H9c2-miR-181-sponge-GFP cells exhibit a loss of function of miR-181 family members as assessed through the increased expression of miR-181 target proteins and compared to H9c2 cells expressing a scramble non-functional sponge. In addition, we develop a nanovector for the systemic delivery of the miR-181-sponge construct by complexing positively charged liposomal nanoparticles and negatively charged miR-181-sponge plasmids. In vivo imaging of GFP reveals that multiple tail vein injections of a nanovector over a three-week period are able to promote a significant expression of the miR-181-sponge in a cardio-specific manner. Importantly, a loss of miR-181 function is observed in the heart tissue but not in the kidney or the liver. The miRNA-sponge is a powerful method to inhibit tissue-specific miRNA expression. Driving the miRNA-sponge expression from a tissue-specific promoter provides specificity for the miRNA inhibition, which can be confined to a targeted organ or tissue. Furthermore, combining nanovector and miRNA-sponge technologies permits an effective delivery and tissue-specific miRNA inhibition in vivo.

In Vivo Nanovector Delivery of a Heart-specific MicroRNA-sponge

Tissue-specific microRNA inhibition is a technology that is underdeveloped in the microRNA field. Herein, we describe a protocol to successfully inhibit the miR-181 microRNA family in myoblast cells from the heart. Nanovector technology is used to deliver a microRNA sponge that demonstrates significant in vivo cardio-specific miR-181 family inhibition.

MicroRNA (miRNA) is small non-coding RNA which inhibits post-transcriptional messenger RNA (mRNA) expression. Human diseases, such as cancer and ...

Biology

CRISPR Gene Editing Tool for MicroRNA Cluster Network Analysis

MicroRNAs (miRNAs) have emerged as important cellular regulators (tumor suppressors, pro-oncogenic factors) of cancer and metastasis. Most published studies focus on a single miRNA when characterizing the role of small RNAs in cancer. However, ~30%&#160;of human miRNA genes are organized in clustered units that are often co-expressed, indicating a complex and coordinated system of noncoding RNA regulation. A clearer understating of how clustered miRNA networks function cooperatively to regulate tumor growth, cancer aggressiveness, and drug resistance is required before translating noncoding small RNAs to the clinic.
The use of a high-throughput clustered regularly interspaced short palindromic repeats (CRISPR)-mediated gene editing procedure has been employed to study the oncogenic role of a genomic cluster of seven miRNA genes located within a locus spanning ~35,000 bp in length in the context of prostate cancer. For this approach, human cancer cell lines were infected with a lentivirus vector for doxycycline (DOX)-inducible Cas9 nuclease grown in DOX-containing medium for 48 h. The cells were subsequently co-transfected with synthetic trans-activating CRISPR RNA (tracrRNA) complexed with genomic site-specific CRISPR RNA (crRNA) oligonucleotides to allow the rapid generation of cancer cell lines carrying the entire miRNA cluster deletion and individual or combination miRNA gene cluster deletions within a single experiment.
The advantages of this high-throughput gene editing system are the ability to avoid time-consuming DNA vector subcloning, the flexibility in transfecting cells with unique guide RNA combinations in a 24-well format, and the lower-cost PCR genotyping using crude cell lysates. Studies using this streamlined approach promise to uncover functional redundancies and synergistic/antagonistic interactions between miRNA cluster members, which will aid in characterizing the complex small noncoding RNA networks involved in human disease and better inform future therapeutic design.

This protocol describes a high-throughput clustered regularly interspaced short palindromic repeats (CRISPR) gene editing workflow for microRNA cluster network analysis that allows the rapid generation of a panel of genetically modified cell lines carrying unique miRNA cluster member deletion combinations as large as 35 kb within a single experiment.

MicroRNAs (miRNAs) have emerged as important cellular regulators (tumor suppressors, pro-oncogenic factors) of cancer and metastasis. Most published ...

A Simple Alternative to Stereotactic Injection for Brain Specific Knockdown of miRNA

Summary

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Chapters in this video

Stereotactic Injection of MicroRNA-expressing Lentiviruses to the Mouse Hippocampus CA1 Region and Assessment of the Behavioral Outcome

Systemic Delivery of MicroRNA Using Recombinant Adeno-associated Virus Serotype 9 to Treat Neuromuscular Diseases in Rodents

In Vivo Inhibition of MicroRNA to Decrease Tumor Growth in Mice

Characterization of Functionally Associated miRNAs in Glioblastoma and their Engineering into Artificial Clusters for Gene Therapy

In ovo Electroporation of miRNA-based Plasmids in the Developing Neural Tube and Assessment of Phenotypes by DiI Injection in Open-book Preparations

A Positioning Device for the Placement of Mice During Intranasal siRNA Delivery to the Central Nervous System

Combining Optogenetics with Artificial microRNAs to Characterize the Effects of Gene Knockdown on Presynaptic Function within Intact Neuronal Circuits

Loss-of-Function Approach in the Embryonic Chick Retina by Using Tol2 Transposon-Mediated Transgenic Expression of Artificial microRNAs

In Vivo Nanovector Delivery of a Heart-specific MicroRNA-sponge

CRISPR Gene Editing Tool for MicroRNA Cluster Network Analysis