Gli autori ringraziano il personale del nucleo Morfologia e Imaging, del nucleo Genetica Molecolare (Dipartimento di Oftalmologia e Scienze Visive) e del mouse Genetica Nucleo presso la Washington University di St. Louis School of Medicine. Gli autori sono supportati dal piccolo programma di sovvenzioni dal Centro McDonnell per Cellulare e Neurobiologia Molecolare, il Centro Speranza per disordini neurologici, il National Eye Institute (# R01EY022632 a DH), un Istituto Nazionale di Eye Centro Nucleo Grant (# P30EY002687) e un sovvenzione illimitata di ricerca per prevenire la cecità al Dipartimento di Oftalmologia e Scienze Visive.

Etica Dichiarazione: procedure che coinvolgono soggetti animali sono stati approvati dalla cura e l&#39;uso Comitato istituzionale animali (IACUC) presso la Washington University di St. Louis. 1. Allevamento Mouse e genotipizzazione <ol><li> Breed Tg (CAG-LacZ / EGFP-KASH2) topi con Tg (PCP2-Cre) per produrre topi Tg (PCP2Cre CAG-EGFP / KASH2) 19,20. Nota: Mentre il resto di questo protocollo concentra sull&#39;uso della linea Tg (PCP2-Cre) topo per restringere espressione EGFP-KASH2 alle cellule di Purkinje nel cervelletto, una procedura simile può essere seguita con qualsiasi altra Tg (Cre) mouse ( Figura 2A). </li><li> Eseguire genotipizzazione per individuare i cuccioli che ospitano sia transgeni EGFP e Cre come descritto in precedenza 19. </li></ol> 2. Preparazione dei Materiali per la dissezione e tessuto Collection <ol><li> Preparare 100 ml di 30% di saccarosio in PBS (30 g di saccarosio / 100 ml di PBS 1x) e conservare a -20 ° C. Il giorno del tessuto harvesting, disgelo e carico ~ 30-35 ml di soluzione di saccarosio in una siringa da 35 ml per perfusioni transcardial. </li><li> Preparare 40 ml di 4% PFA in PBS (10 ml 16% paraformaldeide e 30 ml PBS). Carico ~ 30-35 ml di 4% PFA in una siringa da 35 ml per perfusioni transcardial. </li><li> Riempire una piastra di coltura tissutale 10 centimetri con 10 ml di PBS per la dissezione dei tessuti. </li><li> Preparare un cocktail di ketamina / xilazina costituito da 16 mg / ml di ketamina e 3 mg / ml xilazina. </li><li> Preparare una soluzione di etanolo al 70% per la dissezione. </li></ol> 3. Dissection e tessuto Collection <ol><li> Usando una siringa da 1 ml, 500 ml di iniettare il cocktail ketamina / xylazina per 25 grammi di peso corporeo ed attendere ~ 15 min. In alternativa, utilizzare un altro metodo di sedazione istituzionalmente riconosciuto che è appropriato per il sistema biologico di interesse. </li><li> Su sedazione, pizzicare delicatamente la zampa posteriore per confermare la mancanza di risposta al dolore, riporre tutte le zampe su un vassoio di polistirolo con il lato dorsale delil mouse verso il basso. </li><li> Spruzzare la addome con 70% etanolo e fare un&#39;incisione dal basso addome alla sommità della gabbia toracica per accedere al cuore. </li><li> Effettuare una piccola incisione nell&#39;atrio destro del cuore e inserire la siringa contenente la soluzione di saccarosio al 30% nel ventricolo sinistro del cuore. </li><li> Profumato la soluzione ad una velocità di ~ 2-5 ml per min. Quando è vuoto, rimuovere la siringa e ripetere con la soluzione PFA 4%. </li><li> Sblocca il mouse dal vassoio di polistirolo e decapitarlo per accedere al cervello. </li><li> Togliere la pelle intorno alla testa dell&#39;animale con pinze e forbici. Fare un buco nella parte posteriore del cranio con un ago e rimuovere con attenzione il cranio con forbici e pinze dissezione. </li><li> Una volta che il cervello è chiaramente accessibile, utilizzare pinze per rimuovere il cervelletto e metterlo in PBS. Bisect cervelletto nel piano sagittale con un bisturi e trasferire la soluzione di saccarosio al 30% per una notte a 4 ° C. Nota: Per prepararesono sezioni di paraffina, fissano il cervelletto notte a 4 ° C in PFA 4% prima di incorporamento dei tessuti e sezionamento. </li></ol> 4. Tissue Processing e sezionamento <ol><li> Preparare una sospensione di ghiaccio secco e butano 2-metil. Consentire la temperatura del bagno si stabilizzi per 5 min. </li><li> Riempire un cryomold con OCT e mettere la metà del cervelletto bipartita nello stampo. </li><li> Utilizzando un microscopio da dissezione e una coppia di pinze posizione cervelletto modo che la superficie bisecata (vicino alla linea mediana del cervelletto) è rivolto verso l&#39;alto. </li><li> Trasferire il cryomold all&#39;impasto ghiaccio secco per 5 minuti fino a quando il composto ottobre ha formato una solida matrice bianco intorno il campione di tessuto. Nota: I campioni congelati possono essere conservati a -20 ° C, se necessario. </li><li> Etichetta pretrattate diapositive poli-lisina per la raccolta sezioni di tessuto e preparare il criostato secondo le istruzioni del produttore per raccogliere 15 micron sezioni del Cerebellum. Per raccogliere sezioni contattare attentamente la sezione PTOM il lato rivestito poli-lisina della slitta. Per mantenere l&#39;orientamento della sezione, non ruotare la slitta durante questa fase. </li><li> Sezioni di tessuto Conservare a -20 ° C fino a procedere con la colorazione e l&#39;imaging. </li></ol> 5. La colorazione e imaging di Cervelletto Sezioni <ol><li> Preparare le seguenti soluzioni prima della colorazione dei tessuti: ~ 50 ml di PBS ~ 5-10 ml di PFA 4% in PBS ~ 10-20 ml di Triton X-100 0,5% siero asino, 10% in PBS </li><li> Sezioni cerebellari disgelo. È importante sottolineare che ridurre al minimo la loro esposizione a qualsiasi fonte di luce continua e intensa per evitare sbiadimento di EGFP. </li><li> Con una penna barriera idrofobica, disegnare un rettangolo intorno alle sezioni di tessuto. </li><li> Post-fissare le sezioni con 4% PFA per 5 min. Usi abbastanza liquido da coprire l&#39;intera area delimitata dalla barriera idrofoba (di solito ~ 500 microlitri). Utilizzare un aspirapolvere o pipetta, rispostare il fissativo essere particolarmente attenti a non disturbare i sezioni di tessuto. </li><li> Con una pipetta, applicare delicatamente PBS sul vetrino senza disturbare le sezioni di tessuto. Dopo 5 min utilizzare il vuoto o pipetta per rimuovere con attenzione il liquido. Ripetere la PBS sciacquare un totale di tre volte. </li><li> Usando una pipetta, applicare con cura la diluizione appropriata di anticorpi primari (3 ml calbindin e / o anticorpi Nesprin2 per 900 ml di soluzione di) nello 0,5% Triton X-100, il 10% di siero asino in PBS. Incubare per un&#39;ora a temperatura ambiente al buio. Nota: EGFP-KASH2 sarà visibile mediante microscopia a fluorescenza diretta su sezioni congelate, e non è necessario utilizzare un anticorpo anti-EGFP. Tuttavia, se sono stati preparati sezioni di paraffina, l&#39;imaging di EGFP-KASH2 richiede immunolocalizzazione con un anticorpo anti-EGFP. </li><li> Rimuovere la soluzione di anticorpi e risciacquare con PBS per tre volte. </li><li> Preparare 1: 1.000 diluizioni di anticorpi secondari Alexa-Fluor in 0,5% Triton X-100,10% di siero asino in PBS e conservare al buio. </li><li> Rimuovere delicatamente la PBS risciacquo finale e applicare la diluizione anticorpo secondario per un&#39;ora al buio. </li><li> Rimuovere la soluzione anticorpo secondario, sciacquare e lavare la sezione tre volte. Se necessario, applicare una colorazione nucleare, come DAPI (~ 300nm), durante la prima applicazione PBS. </li><li> Rimuovere completamente la soluzione di PBS da tutto il tessuto e posto ~ 5-7 ml di mezzo di montaggio sulla sezione di tessuto. Collocare un vetrino di vetro sopra la sezione di tessuto e ritirate ~ 15-30 minuti a temperatura ambiente al buio. </li><li> Utilizzare un microscopio a fluorescenza dotato i filtri appropriati per visualizzare EGFP e qualsiasi altre lunghezze d&#39;onda appropriate per gli anticorpi secondari usati nelle fasi 5.8 / 5.9. A fette cerebellare, utilizzare un obiettivo 20X per visualizzare cerchi nucleari EGFP-KASH2. </li></ol>

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<li>Zhang, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Syne-1+and+Syne-2+play+crucial+roles+in+myonuclear+anchorage+and+motor+neuron+innervation%5BTitle%5D)+AND+%22Development%22%5BJournal%5D)">Syne-1 and Syne-2 play crucial roles in myonuclear anchorage and motor neuron innervation.</a> Development. 134, 901-908 (2007).</li>
<li>Zhang, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Nesprin+1+is+critical+for+nuclear+positioning+and+anchorage%5BTitle%5D)+AND+%22Human+molecular+genetics%22%5BJournal%5D)">Nesprin 1 is critical for nuclear positioning and anchorage.</a> Human molecular genetics. 19, 329-341 (2010).</li>
<li>Stewart-Hutchinson, P. J., Hale, C. M., Wirtz, D., Hodzic, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Structural+requirements+for+the+assembly+of+LINC+complexes+and+their+function+in+cellular+mechanical+stiffness%5BTitle%5D)+AND+%22Experimental+cell+research%22%5BJournal%5D)">Structural requirements for the assembly of LINC complexes and their function in cellular mechanical stiffness.</a> Experimental cell research. 314, 1892-1905 (2008).</li>
<li>Zhang, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((SUN1%2F2+and+Syne%2FNesprin-1%2F2+complexes+connect+centrosome+to+the+nucleus+during+neurogenesis+and+neuronal+migration+in+mice%5BTitle%5D)+AND+%22Neuron%22%5BJournal%5D)">SUN1/2 and Syne/Nesprin-1/2 complexes connect centrosome to the nucleus during neurogenesis and neuronal migration in mice.</a> Neuron. 64, 173-187 (2009).</li>
<li>Razafsky, D., Hodzic, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Temporal+and+tissue-specific+disruption+of+LINC+complexes+in+vivo%5BTitle%5D)+AND+%22Genesis%22%5BJournal%5D)">Temporal and tissue-specific disruption of LINC complexes in vivo.</a> Genesis. 52, 359-365 (2014).</li>
<li>Razafsky, D., Hodzic, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+variant+of+Nesprin1+giant+devoid+of+KASH+domain+underlies+the+molecular+etiology+of+autosomal+recessive+cerebellar+ataxia+type+I%5BTitle%5D)+AND+%22Neurobiology+of+disease%22%5BJournal%5D)">A variant of Nesprin1 giant devoid of KASH domain underlies the molecular etiology of autosomal recessive cerebellar ataxia type I.</a> Neurobiology of disease. 78, 57-67 (2015).</li>
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<li>Razafsky, D. S., Ward, C. L., Kolb, T., Hodzic, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Developmental+regulation+of+linkers+of+the+nucleoskeleton+to+the+cytoskeleton+during+mouse+postnatal+retinogenesis%5BTitle%5D)+AND+%22Nucleus%22%5BJournal%5D)">Developmental regulation of linkers of the nucleoskeleton to the cytoskeleton during mouse postnatal retinogenesis.</a> Nucleus. 4, 399-409 (2013).</li>
</ol>

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La fase più critica per studiare con successo il ruolo di complessi LINC in vivo utilizzando la (/ EGFP-KASH2 CAG-LacZ) modello Tg è quello di individuare una linea di topi Cre adatto (s). Infatti, se Cre è attiva in altri tipi di cellule coinvolte in percorsi simili, può complicare l&#39;interpretazione dei risultati. Quindi, è importante esaminare cellule vicine, come mostrato qui negli strati cellulari e molecolari granuli del cervelletto (Figura 2B). Analogamente, per massimizzare even...

L&#39;involucro nucleare (NE) separa nucleoplasma dal citoplasma. Esso è composto da una membrana nucleare interna ed esterna (INM e ONM, rispettivamente) che collegano a pori nucleari. Il lume delineato da due membrane si chiama lo spazio perinucleare (PNS). Il ONM è un&#39;estensione del reticolo endoplasmatico rugoso (ER) e l&#39;INM aderisce alla lamina nucleare, un reticolo di nucleare tipo V filamenti intermedi rappresentato da A e B lamine di tipo 1,2. Linker del nucleoscheletro e citoscheletro (LINC) sono complessi macromolecolari assemblee che attraversano l&#39;intero involucro nucleare collegare fisicamente l&#39;interno del nucleo di filamenti citoscheletrici e motori molecolari (Figura 1A). Sono costituiti da interazioni tra motivi evolutivamente conservati che caratterizzano due famiglie di proteine ​​transmembrana integranti del NE: Sun (SAD1 / Unc84) proteine ​​e Nesprins (nucleare Envelope SPectRINS). Nei mammiferi, Sun1 e Sun2 are transmembrana proteine ​​della INM la cui regione nucleoplasmic N-terminale interagisce direttamente con A e B lamine di tipo 3-5. Sull&#39;altro lato della INM, all&#39;interno del PNS, proteine ​​Sun Harbor un tratto evolutivo conservata di ~ 150 amminoacidi C-terminale chiamato dominio SUN. Domini SUN interagiscono direttamente con il evolutivo conservata KASH (Klarsicht / Anc-1, Syne omologia) dominio, la firma molecolare di Nesprins. Domini KASH consistono di un tratto di ~ 30 C-terminale amminoacidi che sporge nel PNS seguito da un dominio transmembrana 6. Almeno quattro geni distinti Nesprin (Nesprin1-4) codificano KASH contenenti proteine ​​che localizzano al NE 7. Le regioni citoplasmatici di Nesprins, il cui variare taglie da ~ 50kDa (Nesprin4) a un sorprendente 1.000 kDa (Nesprin1 gigante), contengono spectrina multiplo ripete così come i motivi specifici che consente loro interazione con componenti del citoscheletro, come l&#39;actina, plectina e motori molecolari 8- 13. &lt;p class = &quot;jove_content&quot;&gt; Studi di vertebrati e invertebrati hanno mostrato che / motori molecolari Lamin Sole / Nesprin / costituiscono un &quot;asse&quot; evolutivamente conservata controllare la migrazione nucleare e di ancoraggio. Diversi knock-out (KO) modelli murini di componenti complessi LINC sono stati descritti e sono stati strumentali nel fornire un quadro per capire il ruolo delle proteine ​​Sole e Nesprin a NE durante lo sviluppo dei mammiferi 9,14,15. Tuttavia, questi modelli presentano diversi svantaggi significativi, più in particolare: 1) difficoltà nell&#39;interpretare fenotipi dovuti alla cella effetti non autonomi, 2) difficoltà nel distinguere i contributi fenotipiche di Kash contenenti vs. KASH-meno Nesprin isoforme 16, 3) il la ridondanza funzionale delle proteine ​​Sole e Nesprin al NE in numerosi tipi di cellule richiede sistemi di allevamento complessi per inattivare tutte le interazioni SUN-Kash in topi 17 e 4) la letalità perinatale di topi deficienti per la KASH-dominio di entrambiNesprins1 e 2 preclude l&#39;analisi dei fenotipi adulti 18. Questo protocollo descrive un modello di topo romanzo progettata per distruggere tutte le interazioni SUN-KASH in vivo, in una cella modo autonomo e evolutivamente regolata, bypassando così molti degli inconvenienti sopra delineati. Questo / modello murino basato LOX-Cre si basa su due concetti importanti: 1) il dominio KASH di qualsiasi proteina Nesprin noto è sufficiente per indirizzare EGFP a NE in sistemi di colture cellulari e 2) i domini SUN interagire promiscuamente con i domini Kash, quindi sovraespressione di qualsiasi dominio KASH saturerà tutti i domini SUN endogeni e inattivare complessi LINC in modo negativamente dominante 17 (Figura 1B). Questo protocollo descrive la raccolta dei tessuti e fasi di lavorazione utilizzate per confermare l&#39;interruzione di tutte le interazioni SUN-Kash in cellule di Purkinje cerebellari.

<table><tbody><tr><td>Sucrose</td><td>Sigma Aldrich</td><td>S0389</td><td></td></tr><tr><td>10x PBS</td><td>Gibco</td><td>14200-075</td><td></td></tr><tr><td>16% Paraformaldehyde Solution</td><td>Electron Microscopy Sciences</td><td>15710</td><td></td></tr><tr><td>OCT Compound</td><td>Tissue-Tek</td><td>4583</td><td></td></tr><tr><td>Adhesion Slides</td><td>StatLab</td><td>M1000W</td><td></td></tr><tr><td>Donkey Serum</td><td>Sigma Aldrich</td><td>D9663</td><td></td></tr><tr><td>Triton X-100</td><td>Sigma Aldrich</td><td>T9284</td><td></td></tr><tr><td>ImmuEdge Pen</td><td>Vector Laboratories</td><td>H-4000</td><td></td></tr><tr><td>Anti-Calbindin Antibody</td><td>Sigma Aldrich</td><td>C9848</td><td></td></tr><tr><td>Anti-EGFP Antibody</td><td>Abcam</td><td>ab13970</td><td></td></tr><tr><td>Anti-Nesprin2 Antibody</td><td></td><td></td><td>Previously described in Ref. 21</td></tr><tr><td>Fluorescent Mounting Media</td><td>Dako</td><td>S3023</td><td></td></tr><tr><td>2-methyl butane</td><td>Sigma Aldrich</td><td>O3551</td><td></td></tr></tbody></table>

validation of a mouse model to disrupt linc complexes in a cell-specific manner

Nuclear migration and anchorage within developing and adult tissues relies heavily upon large macromolecular protein assemblies called LInkers of the Nucleoskeleton and Cytoskeleton (LINC complexes). These protein scaffolds span the nuclear envelope and connect the interior of the nucleus to components of the surrounding cytoplasmic cytoskeleton. LINC complexes consist of two evolutionary-conserved protein families, Sun proteins and Nesprins that harbor C-terminal molecular signature motifs called the SUN and KASH domains, respectively. Sun proteins are transmembrane proteins of the inner nuclear membrane whose N-terminal nucleoplasmic domain interacts with the nuclear lamina while their C-terminal SUN domains protrudes into the perinuclear space and interacts with the KASH domain of Nesprins. Canonical Nesprin isoforms have a variable sized N-terminus that projects into the cytoplasm and interacts with components of the cytoskeleton. This protocol describes the validation of a dominant-negative transgenic mouse strategy that disrupts endogenous SUN/KASH interactions in a cell-type specific manner. Our approach is based on the Cre/Lox system that bypasses many drawbacks such as perinatal lethality and cell nonautonomous phenotypes that are associated with germline models of LINC complex inactivation. For this reason, this model provides a useful tool to understand the role of LINC complexes during development and homeostasis in a wide array of tissues.

Questo protocollo illustra l&#39;utilità del (/ EGFP-KASH2 CAG-LacZ) modello di topo Tg di limitare l&#39;espressione EGFP-KASH2 alle cellule di Purkinje cerebellari utilizzando Tg (PCP2-Cre) topi. Nel Tg (PCP2Cre CAG-EGFP / KASH2) prole, la griglia di lettura aperta LacZ / V5 è asportato in P6 dalla ricombinasi Cre determinando così l&#39;espressione di EGFP-KASH2 specificamente mirato al Purkinje cellule (Figura 2A). Come previsto, EGFP-KASH2 è rivolto a membrana nucleare come indicato ...

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Validation of a Mouse Model to Disrupt LINC Complexes in a Cell-specific Manner

Nuclear envelope proteins play a central role in many basic biological processes and have been implicated in a variety of human diseases. This protocol describes a new Cre/Lox-based mouse model that allows for the spatiotemporal control of LINC complexes disruption.

La convalida di un modello di topo per Disrupt LINC Complessi in modo specifico-Cell

Nuclear migration and anchorage within developing and adult tissues relies heavily upon large macromolecular protein assemblies called LInkers of the ...

validation-mouse-model-to-disrupt-linc-complexes-cell-specific

Research

JoVE Journal

Biology

7.3K Views.  Washington University in St. Louis School of Medicine. Nuclear envelope proteins play a central role in many basic biological processes and have been implicated in a variety of human diseases. This protocol describes a new Cre/Lox-based mouse model that allows for the spatiotemporal control of LINC complexes disruption.

Video: Validation of a Mouse Model to Disrupt LINC Complexes in a Cell-specific Manner

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.

Iniezione stereotassica di microRNA-esprimono lentivirus al mouse Hippocampus CA1 regione e valutazione dei risultati Behavioral

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

Ricerca

Comportamento

Using Mouse Oocytes to Assess Human Gene Function During Meiosis I

Embryonic aneuploidy is the major genetic cause of infertility in humans. Most of these events originate during female meiosis, and albeit positively correlated with maternal age, age alone is not always predictive of the risk of generating an aneuploid embryo. Therefore, gene variants might account for incorrect chromosome segregation during oogenesis. Given that access to human oocytes is limited for research purposes, a series of assays were developed to study human gene function during meiosis I using mouse oocytes. First, messenger RNA (mRNA) of the gene and gene variant of interest are microinjected into prophase I-arrested mouse oocytes. After allowing time for expression, oocytes are synchronously released into meiotic maturation to complete meiosis I. By tagging the mRNA with a sequence of a fluorescent reporter, such as green fluorescent protein (Gfp), the localization of the human protein can be assessed in addition to the phenotypic alterations. For example, gain or loss of function can be investigated by establishing experimental conditions that challenge the gene product to fix meiotic errors. Although this system is advantageous in investigating human protein function during oogenesis, adequate interpretation of results should be undertaken given that protein expression is not at endogenous levels and, unless controlled for (i.e. knocked out or down), murine homologs are also present in the system.

As the genetic variants associated with human disease begin to become uncovered, it is becoming increasingly important to develop systems with which to rapidly evaluate the biological significance of those identified variants. This protocol describes methods for evaluating human gene function during female meiosis I using mouse oocytes.

Usando i Oocytes del Mouse per valutare la funzione del Gene umano durante la meiosi I

Embryonic aneuploidy is the major genetic cause of infertility in humans. Most of these events originate during female meiosis, and albeit positively ...

Genetica

A Non-random Mouse Model for Pharmacological Reactivation of Mecp2 on the Inactive X Chromosome

X chromosome inactivation (XCI) is the random silencing of one X chromosome in females to achieve gene dosage balance between the sexes. As a result, all females are heterozygous for X-linked gene expression. One of the key regulators of XCI is Xist, which is essential for the initiation and maintenance of XCI. Previous studies have identified 13 trans acting X chromosome inactivation factors (XCIFs) using a large-scale, loss-of-function genetic screen. Inhibition of XCIFs, such as ACVR1 and PDPK1, using short-hairpin RNA or small molecule inhibitors, reactivates X chromosome-linked genes in cultured cells. But the feasibility and tolerability of reactivating the inactive X chromosome in vivo remains to be determined. Towards this goal, a Xist&#916;:Mecp2/Xist:Mecp2-Gfp mouse model has been generated with non-random XCI due to deletion of Xist on one X chromosome. Using this model, the extent of inactive X reactivation was quantitated in the mouse brain following treatment with XCIF inhibitors. Recently published results show, for the first time, that pharmacological inhibition of XCIFs reactivates Mecp2 from the inactive X chromosome in cortical neurons of the living mouse brain.

Here, we describe a protocol to generate a viable female murine model with non-random X chromosome inactivation, i.e., the maternally-inherited X chromosome is inactive in 100% of the cells. We also describe a protocol to test feasibility, tolerability, and safety of pharmacological reactivation of the inactive X chromosome in vivo.

Un modello di mouse non casuale per la riattivazione farmacologica di MECP2 sul cromosoma X inattivo

X chromosome inactivation (XCI) is the random silencing of one X chromosome in females to achieve gene dosage balance between the sexes. As a result, all ...

Identifying DNA Mutations in Purified Hematopoietic Stem/Progenitor Cells

In recent years, it has become apparent that genomic instability is tightly related to many developmental disorders, cancers, and aging. Given that stem cells are responsible for ensuring tissue homeostasis and repair throughout life, it is reasonable to hypothesize that the stem cell population is critical for preserving genomic integrity of tissues. Therefore, significant interest has arisen in assessing the impact of endogenous and environmental factors on genomic integrity in stem cells and their progeny, aiming to understand the etiology of stem-cell based diseases.
LacI transgenic mice carry a recoverable &#955;&#160;phage vector encoding the LacI reporter system, in which the LacI gene serves as the mutation reporter. The result of a mutated LacI gene is the production of &#946;-galactosidase that cleaves a chromogenic substrate, turning it blue. The LacI reporter system is carried in all cells, including stem/progenitor cells and can easily be recovered and used to subsequently infect E. coli. After incubating infected E. coli on agarose that contains the correct substrate, plaques can be scored; blue plaques indicate a mutant LacI gene, while clear plaques harbor wild-type. The frequency of blue (among clear) plaques indicates the mutant frequency in the original cell population the DNA was extracted from. Sequencing the mutant LacI gene will show the location of the mutations in the gene and the type of mutation.
The LacI transgenic mouse model is well-established as an in vivo mutagenesis assay. Moreover, the mice and the reagents for the assay are commercially available. Here we describe in detail how this model can be adapted to measure the frequency of spontaneously occurring DNA mutants in stem cell-enriched Lin-IL7R-Sca-1+cKit++(LSK) cells and other subpopulations of the hematopoietic system.

Here we describe an in vivo mutagenesis assay for small numbers of purified hematopoietic cells using the LacI transgenic mouse model.&#160;The LacI gene can be isolated to determine the frequency, location, and type of DNA mutants&#160;spontaneously arisen or after exposure to genotoxins.

L&#39;identificazione del DNA Mutazioni in depurata ematopoietiche cellule staminali / progenitrici

In recent years, it has become apparent that genomic instability is tightly related to many developmental disorders, cancers, and aging. Given that stem ...

Immunologia e infezioni

Mouse In Vivo Placental Targeted CRISPR Manipulation

The placenta is an essential organ that regulates and maintains mammalian development in utero. The placenta is responsible for the transfer of nutrients and waste between the mother and fetus and the production and delivery of growth factors and hormones. Placental genetic manipulations in mice are critical for understanding the placenta's specific role in prenatal development. Placental-specific Cre-expressing transgenic mice have varying effectiveness, and other methods for placental gene manipulation can be useful alternatives. This paper describes a technique to directly alter placental gene expression using CRISPR gene manipulation, which can be used to modify the expression of targeted genes. Using a relatively advanced surgical approach, pregnant dams undergo a laparotomy on embryonic day 12.5 (E12.5), and a CRISPR plasmid is delivered by a glass micropipette into the individual placentas. The plasmid is immediately electroporated after each injection. After dam recovery, the placentas and embryos can continue development until assessment at a later time point. The evaluation of the placenta and offspring after the use of this technique can determine the role of time-specific placental function in development. This type of manipulation will allow for a better understanding of how placental genetics and function impact fetal growth and development in multiple disease contexts.

Mouse In Vivo Placental Targeted CRISPR Manipulation

Here we describe a time-specific method to effectively manipulate critical developmental pathways in the mouse placenta in vivo. This is performed through the injection and electroporation of CRISPR plasmids into the placentas of pregnant dams on embryonic day 12.5.

Manipolazione CRISPR mirata alla placenta del mouse in vivo

The placenta is an essential organ that regulates and maintains mammalian development in utero. The placenta is responsible for the transfer of nutrients ...

Stereotaxic Injection of a Viral Vector for Conditional Gene Manipulation in the Mouse Spinal Cord

Intraparenchymal injection of a viral vector enables conditional gene manipulation in distinct populations of neurons or particular regions of the central nervous system. We demonstrate a stereotaxic injection technique that allows targeted gene expression or silencing in the dorsal horn of the mouse spinal cord. The surgical procedure is brief. It requires laminectomy of a single vertebra, providing for quick recovery of the animal and unimpaired motility of the spine. Controlled injection of a small vector suspension volume at low speed and use of a microsyringe with beveled glass cannula minimize the tissue lesion. The local immune response to the vector depends on the intrinsic properties of the virus employed; in our experience, it is minor and short-lived when a recombinant adeno-associated virus is used. A reporter gene such as enhanced green fluorescent protein facilitates monitoring spatial distribution of the vector, and the efficacy and cellular specificity of the transfection.

Viral vectors allow for targeted gene manipulation. We demonstrate a method for conditional gene expression or ablation in the mouse spinal cord, using stereotaxic injection of a viral vector into the dorsal horn, a prominent site of synaptic contact between primary somatosensory afferents and neurons of the central nervous system.

Iniezione stereotassica di un vettore virale per la manipolazione del gene condizionale nel midollo spinale del mouse

Intraparenchymal injection of a viral vector enables conditional gene manipulation in distinct populations of neurons or particular regions of the central ...

Neuroscienze

Inducing Cre-lox Recombination in Mouse Cerebral Cortex Through In Utero Electroporation

Cell-autonomous neuronal functions of genes can be revealed by causing loss or gain of function of a gene in a small and sparse population of neurons. To do so requires generating a mosaic in which neurons with loss or gain of function of a gene are surrounded by genetically unperturbed tissue. Here, we combine the Cre-lox recombination system with in utero electroporation in order to generate mosaic brain tissue that can be used to study the cell-autonomous function of genes in neurons. DNA constructs (available through repositories), coding for a fluorescent label and Cre recombinase, are introduced into developing cortical neurons containing genes flanked with loxP sites in the brains of mouse embryos using in utero electroporation. Additionally, we describe various adaptations to the in utero electroporation method that increase survivability and reproducibility. This method also involves establishing a titer for Cre-mediated recombination in a sparse or dense population of neurons. Histological preparations of labeled brain tissue do not require (but can be adapted to) immunohistochemistry. The constructs used guarantee that fluorescently labeled neurons carry the gene for Cre recombinase. Histological preparations allow morphological analysis of neurons through confocal imaging of dendritic and axonal arbors and dendritic spines. Because loss or gain of function is achieved in sparse mosaic tissue, this method permits the study of cell-autonomous necessity and sufficiency of gene products in vivo.

Inducing Cre-lox Recombination in Mouse Cerebral Cortex Through In Utero Electroporation

Cell-autonomous functions of genes in the brain can be studied by inducing loss or gain of function in sparse populations of cells. Here, we describe in utero electroporation to deliver Cre recombinase into sparse populations of developing cortical neurons with floxed genes to cause loss of function in vivo.

Induzione della ricombinazione di Cre-lox nella corteccia cerebrale del Mouse attraverso elettroporazione In Utero

Cell-autonomous neuronal functions of genes can be revealed by causing loss or gain of function of a gene in a small and sparse population of neurons. To ...

Mouse Genome Engineering Using Designer Nucleases

Transgenic mice carrying site-specific genome modifications (knockout, knock-in) are of vital importance for dissecting complex biological systems as well as for modeling human diseases and testing therapeutic strategies. Recent advances in the use of designer nucleases such as zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) 9 system for site-specific genome engineering open the possibility to perform rapid targeted genome modification in virtually any laboratory species without the need to rely on embryonic stem (ES) cell technology. A genome editing experiment typically starts with identification of designer nuclease target sites within a gene of interest followed by construction of custom DNA-binding domains to direct nuclease activity to the investigator-defined genomic locus. Designer nuclease plasmids are in vitro transcribed to generate mRNA for microinjection of fertilized mouse oocytes. Here, we provide a protocol for achieving targeted genome modification by direct injection of TALEN mRNA into fertilized mouse oocytes.

Designer nucleases such as zinc finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs) can be used to modify the genome of mouse preimplantation embryos by triggering both the nonhomologous end joining (NHEJ) and homologous recombination (HR) pathways. These advances enable the rapid generation of mice with precise genetic modifications.

Genoma Ingegneria mouse usando Nucleases Designer

Transgenic mice carrying site-specific genome modifications (knockout, knock-in) are of vital importance for dissecting complex biological systems as well ...

Biologia

Modeling Prostate Cancer in Genetically-engineered Mouse Models: A CRISPR/Cas9-mediated Localized Gene Editing Technique in Mouse Anterior Prostate Lobe Cells

Source: Riedel, M. et al. <a href="https://www.jove.com/video/57525" target="_blank">Virus Delivery of CRISPR Guides to the Murine Prostate for Gene Alteration.</a> J. Vis. Exp. (2018)
This video describes a method for editing specific genes in prostate gland cells using an adenovirus-based delivery system. The approach allows for orthotopic and localized alteration of gene expression utilizing CRISPR technology to develop novel mouse models for prostate cancer.

Modellazione del cancro alla prostata in modelli murini geneticamente modificati: una tecnica di editing genico localizzato mediata da CRISPR/Cas9 nelle cellule del lobo prostatico anteriore del topo

Source: Riedel, M. et al. Virus Delivery of CRISPR Guides to the Murine Prostate for Gene Alteration. J. Vis. Exp. (2018)
This video describes a method ...

JoVE Encyclopedia of Experiments

Ricerca sul cancro

Prostate Cancer

Animal model studies

Establishing a Focal Demyelination Mouse Model via a Two-Point Injection of Lysophosphatidylcholine

Source: Pang, X., et al. <a href="https://app.jove.com/v/64059">A Stably Established Two-Point Injection of Lysophosphatidylcholine-Induced Focal Demyelination Model in Mice.</a> J. Vis. Exp. (2022)
This video demonstrates the generation of a focal demyelination mouse model using a two-point Lysophosphatidylcholine (LPC) injection. The skull of an anesthetized mouse is exposed. The injection coordinates are determined, and a hole is drilled to enable LPC injections at targeted sites. LPC induces focal demyelination of neurons via inflammation, while a two-point injection ensures its sustainability.

Source: Pang, X., et al. A Stably Established Two-Point Injection of Lysophosphatidylcholine-Induced Focal Demyelination Model in Mice. J. Vis. Exp. ...