live-imaging-of-mitosis-in-the-developing-mouse-embryonic-cortex

Live Imaging of Mitosis in the Developing Mouse Embryonic Cortex

Although of short duration, mitosis is a complex and dynamic multi-step process fundamental for development of organs including the brain. In the ...

Duke University Medical Center

New work in Drosophila demonstrates that cdk4 loss causes phenotypes similar to the loss of JAK/STAT pathway components. Cdk4 overexpression can bypass requirements for JAK but not STAT. These results demonstrate a new function for Cdk4 and a new mode of STAT activation.

A new trick for Cyclin-Cdk: activation of STAT.

Constitutive activation of the Janus-activated kinase/signal transducer and activator of transcription (STAT) pathway promotes the proliferation and survival of cancer cells in culture and is associated with various cancers, including those of the ovary. We found that constitutively activated STAT3 levels correlated with aggressive clinical behavior of ovarian carcinoma specimens. Furthermore, inhibition of STAT3 reduced the motility of ovarian cancer cells in vitro. Surprisingly, we found that activated STAT3 localized not only to nuclei but also to focal adhesions in these cells. Activated STAT3 coimmunoprecipitated with phosphorylated paxillin and focal adhesion kinase and required paxillin and Src for its localization to focal adhesions. These results suggest that Janus-activated kinase/STAT signaling may contribute to ovarian cancer cell invasiveness.

Activated signal transducer and activator of transcription (STAT) 3: localization in focal adhesions and function in ovarian cancer cell motility.

The evolutionarily conserved JAK/STAT signaling pathway is essential for the proliferation, survival and differentiation of many cells including cancer cells. Recent studies have implicated this transcriptional pathway in the process of cell migration in humans, mice, Drosophila and Dictyostelium. In the Drosophila ovary, JAK/STAT signaling is necessary and sufficient for the specification and migration of a group of cells called the border cells; however, it is not clear to what extent the requirement for cell fate is distinct from that for cell migration. We found that STAT protein is enriched in the migrating border cells throughout their migration and is an indicator of cells with highest JAK/STAT activity. In addition, stat(ts) mutants exhibited border cell migration defects after just 30 minutes at the non-permissive temperature, prior to any detectable change in the expression of cell fate markers. At later times, cell fate changes became evident, indicating that border cell fate is labile. JAK/STAT signaling was also required for organization of the border cell cluster. Finally, we show that both the accumulation of STAT protein and nuclear accumulation are positively regulated by JAK/STAT activity. The activity of the pathway is negatively regulated by overexpression of a SOCS protein and by blocking endocytosis. Together, our findings suggest that the requirement for STAT in border cells extends beyond the initial specification and delamination of cells from the epithelium.

Requirement for JAK/STAT signaling throughout border cell migration in Drosophila.

Pigment cells in developing vertebrates are derived from a transient and pluripotent population of cells called neural crest. The neural crest delaminates from the developing neural tube and overlying ectoderm early in development. The pigment cells are the only derivative to migrate along the dorso-lateral pathway. As they migrate, the precursor pigment cell population differentiates and expands through proliferation and pro-survival processes, ultimately contributing to the coloration of organisms. The types of pigment cells that develop, timing of these processes, and final destination can vary between organisms. Studies from mice, chick, Xenopus, zebrafish, and medaka have led to the identification of many genes that regulate pigment cell development. These include several classes of proteins: transcription factors, transmembrane receptors, and extracellular ligands. This chapter discusses an overview of pigment cell development and the genes that regulate this important process.

The genetic regulation of pigment cell development.

Haploinsufficiency for the transcription factor SOX10 is associated with the pigmentary deficiencies of Waardenburg syndrome (WS) and is modeled in Sox10 haploinsufficient mice (Sox10(LacZ/+)). As genetic background affects WS severity in both humans and mice, we established an N-ethyl-N-nitrosourea (ENU) mutagenesis screen to identify modifiers that increase the phenotypic severity of Sox10(LacZ/+) mice. Analysis of 230 pedigrees identified three modifiers, named modifier of Sox10 neurocristopathies (Mos1, Mos2 and Mos3). Linkage analysis confirmed their locations on mouse chromosomes 13, 4 and 3, respectively, within regions distinct from previously identified WS loci. Positional candidate analysis of Mos1 identified a truncation mutation in a hedgehog(HH)-signaling mediator, GLI-Kruppel family member 3 (Gli3). Complementation tests using a second allele of Gli3 (Gli3(Xt-J)) confirmed that a null mutation of Gli3 causes the increased hypopigmentation in Sox10(LacZ/+);Gli3(Mos1/)(+) double heterozygotes. Early melanoblast markers (Mitf, Sox10, Dct, and Si) are reduced in Gli3(Mos1/)(Mos1) embryos, indicating that loss of GLI3 signaling disrupts melanoblast specification. In contrast, mice expressing only the GLI3 repressor have normal melanoblast specification, indicating that the full-length GLI3 activator is not required for specification of neural crest to the melanocyte lineage. This study demonstrates the feasibility of sensitized screens to identify disease modifier loci and implicates GLI3 and other HH signaling components as modifiers of human neurocristopathies.

A sensitized mutagenesis screen identifies Gli3 as a modifier of Sox10 neurocristopathy.

ADAMTS20 (Adisintegrin-like and metalloprotease domain with thrombospondin type-1 motifs) is a member of a family of secreted metalloproteases that can process a variety of extracellular matrix (ECM) components and secreted molecules. Adamts20 mutations in belted (bt) mice cause white spotting of the dorsal and ventral torso, indicative of defective neural crest (NC)-derived melanoblast development. The expression pattern of Adamts20 in dermal mesenchymal cells adjacent to migrating melanoblasts led us to initially propose that Adamts20 regulated melanoblast migration. However, using a Dct-LacZ transgene to track melanoblast development, we determined that melanoblasts were distributed normally in whole mount E12.5 bt/bt embryos, but were specifically reduced in the trunk of E13.5 bt/bt embryos due to a seven-fold higher rate of apoptosis. The melanoblast defect was exacerbated in newborn skin and embryos from bt/bt animals that were also haploinsufficient for Adamts9, a close homolog of Adamts20, indicating that these metalloproteases functionally overlap in melanoblast development. We identified two potential mechanisms by which Adamts20 may regulate melanoblast survival. First, skin explant cultures demonstrated that Adamts20 was required for melanoblasts to respond to soluble Kit ligand (sKitl). In support of this requirement, bt/bt;Kit(tm1Alf)/+ and bt/bt;Kitl(Sl)/+ mice exhibited synergistically increased spotting. Second, ADAMTS20 cleaved the aggregating proteoglycan versican in vitro and was necessary for versican processing in vivo, raising the possibility that versican can participate in melanoblast development. These findings reveal previously unrecognized roles for Adamts proteases in cell survival and in mediating Kit signaling during melanoblast colonization of the skin. Our results have implications not only for understanding mechanisms of NC-derived melanoblast development but also provide insights on novel biological functions of secreted metalloproteases.

The secreted metalloprotease ADAMTS20 is required for melanoblast survival.

We show that combinatorial mouse alleles for the secreted metalloproteases Adamts5, Adamts20 (bt), and Adamts9 result in fully penetrant soft-tissue syndactyly. Interdigital webs in Adamts5(-/-);bt/bt mice had reduced apoptosis and decreased cleavage of the proteoglycan versican; however, the BMP-FGF axis, which regulates interdigital apoptosis was unaffected. BMP4 induced apoptosis, but without concomitant versican proteolysis. Haploinsufficiency of either Vcan or Fbln1, a cofactor for versican processing by ADAMTS5, led to highly penetrant syndactyly in bt mice, suggesting that cleaved versican was essential for web regression. The local application of an aminoterminal versican fragment corresponding to ADAMTS-processed versican, induced cell death in Adamts5(-/-);bt/bt webs. Thus, ADAMTS proteases cooperatively maintain versican proteolysis above a required threshold to create a permissive environment for apoptosis. The data highlight the developmental significance of proteolytic action on the ECM, not only as a clearance mechanism, but also as a means to generate bioactive versican fragments.

ADAMTS metalloproteases generate active versican fragments that regulate interdigital web regression.

&#x5927;&#x8111;&#x7ED3;&#x6784;&#x548C;&#x5C3A;&#x5BF8;&#x8981;&#x6C42;&#x51C6;&#x786E;&#x5730;&#x5212;&#x5206;&#x7684;&#x795E;&#x7ECF;&#x5E72;&#x7EC6;&#x80DE; (&#x795E;&#x7ECF;&#x5E72;&#x7EC6;&#x80DE;&#xFF09;&#xFF0C;&#x5176;&#x4E2D; self-renew &#x548C;&#x751F;&#x6210;&#x4E2D;&#x95F4;&#x795E;&#x7ECF;&#x7956;&#x7EC6;&#x80DE; (&#x7EFC;&#x5408;&#x90BB;&#x820D;&#x8BA1;&#x5212;&#xFF09; &#x548C;&#x795E;&#x7ECF;&#x5143;&#x3002;&#x8C03;&#x8282;&#x795E;&#x7ECF;&#x5E72;&#x7EC6;&#x80DE;&#x7684;&#x56E0;&#x7D20;&#x4ECD;&#x7136;&#x662F;&#x591A;&#x4E48;&#x5F02;&#x5E38; NSC &#x53F8;&#x539F;&#x56E0;&#x7F3A;&#x4E4F;&#x89C1;&#x4E8E;&#x5C0F;&#x5934;&#x7578;&#x5F62;&#x7684;&#x5927;&#x5C0F;&#x51CF;&#x5C11;&#x7684;&#x5927;&#x8111;&#x7684;&#x7406;&#x89E3;&#x5F88;&#x5DEE;&#xFF0C;&#x548C;&#x673A;&#x68B0;&#x89E3;&#x91CA;&#x3002;&#x5728;&#x8FD9;&#x91CC;&#x6211;&#x4EEC;&#x663E;&#x793A; Magoh&#xFF0C;&#x7EC4;&#x4EF6;&#x5916;&#x663E;&#x5B50;&#x4EA4;&#x754C;&#x7684;&#x590D;&#x6742; (EJC) &#x7ED1;&#x5B9A; RNA&#xFF0C;&#x901A;&#x8FC7;&#x8C03;&#x8282; NSC &#x53F8;&#x63A7;&#x5236;&#x9F20;&#x6807;&#x8111;&#x76AE;&#x8D28;&#x5927;&#x5C0F;&#x3002;Magoh haploinsufficiency INP &#x67AF;&#x7AED;&#x548C;&#x795E;&#x7ECF;&#x5143;&#x51CB;&#x4EA1;&#x5BFC;&#x81F4;&#x5C0F;&#x5934;&#x7578;&#x5F62;&#x3002;&#x6709;&#x7F3A;&#x9677;&#x7684;&#x7EC6;&#x80DE;&#x6709;&#x4E1D;&#x5206;&#x88C2;&#x662F;&#x57FA;&#x7840;&#x8FD9;&#x4E9B;&#x8868;&#x578B;&#xFF0C;&#x5982;&#x6D88;&#x8017; EJC &#x7EC4;&#x4EF6;&#x6270;&#x4E71;&#x4E86;&#x6709;&#x4E1D;&#x5206;&#x88C2;&#x7684;&#x4E3B;&#x8F74;&#x65B9;&#x5411;&#x548C;&#x5B8C;&#x6574;&#x6027;&#x3001; &#x67D3;&#x8272;&#x4F53;&#x6570;&#x76EE;&#x548C;&#x57FA;&#x56E0;&#x7EC4;&#x7684;&#x7A33;&#x5B9A;&#x3002;&#x5BAB;&#x5185;&#x6551;&#x63F4;&#x5B9E;&#x9A8C;&#x8868;&#x660E; Magoh &#x7684;&#x4E00;&#x9879;&#x5173;&#x952E;&#x529F;&#x80FD;&#x662F;&#x63A7;&#x5236;&#x795E;&#x7ECF;&#x53D1;&#x751F;&#x8FC7;&#x7A0B;&#x4E2D;&#x7684;&#x5C0F;&#x5934;&#x7578;&#x5F62;&#x76F8;&#x5173;&#x86CB;&#x767D; Lis1 &#x7684;&#x6C34;&#x5E73;&#x3002;&#x6211;&#x4EEC;&#x7684;&#x7814;&#x7A76;&#x7ED3;&#x679C;&#x63ED;&#x793A; EJC &#x8111;&#x53D1;&#x80B2;&#x3001; &#x795E;&#x7ECF;&#x5E72;&#x7EC6;&#x80DE;&#x7EF4;&#x62A4;&#x548C;&#x6709;&#x4E1D;&#x5206;&#x88C2;&#xFF0C;&#x4ECE;&#x800C;&#x7275;&#x8FDE;&#x8FD9;&#x5C0F;&#x5934;&#x7578;&#x5F62;&#x53D1;&#x75C5;&#x673A;&#x5236;&#x4E2D;&#x7684;&#x590D;&#x6742;&#x7684;&#x8981;&#x6C42;&#x3002;

&#x5916;&#x663E;&#x5B50;&#x4EA4;&#x754C;&#x5904;&#x590D;&#x6742;&#x7EC4;&#x4EF6; Magoh &#x63A7;&#x4EF6;&#x901A;&#x8FC7;&#x8C03;&#x8282;&#x795E;&#x7ECF;&#x5E72;&#x7EC6;&#x80DE;&#x5206;&#x88C2;&#x8111;&#x7684;&#x5927;&#x5C0F;&#x3002;

Brain structure and size require precise division of neural stem cells (NSCs), which self-renew and generate intermediate neural progenitors (INPs) and neurons. The factors that regulate NSCs remain poorly understood, and mechanistic explanations of how aberrant NSC division causes the reduced brain size seen in microcephaly are lacking. Here we show that Magoh, a component of the exon junction complex (EJC) that binds RNA, controls mouse cerebral cortical size by regulating NSC division. Magoh haploinsufficiency causes microcephaly because of INP depletion and neuronal apoptosis. Defective mitosis underlies these phenotypes, as depletion of EJC components disrupts mitotic spindle orientation and integrity, chromosome number and genomic stability. In utero rescue experiments showed that a key function of Magoh is to control levels of the microcephaly-associated protein Lis1 during neurogenesis. Our results uncover requirements for the EJC in brain development, NSC maintenance and mitosis, thereby implicating this complex in the pathogenesis of microcephaly.

The exon junction complex component Magoh controls brain size by regulating neural stem cell division.

La structure du cerveau et de taille n&#xE9;cessitent une r&#xE9;partition pr&#xE9;cise des cellules souches neurales (CSN), qui s&#x26;#39;auto-renouveler et de g&#xE9;n&#xE9;rer des interm&#xE9;diaires prog&#xE9;niteurs neuronaux (INPS) et de neurones. Les facteurs qui r&#xE9;gulent NSCs demeurent mal comprises, et des explications m&#xE9;canistes de la fa&#xE7;on dont la division aberrante NSC provoque la taille r&#xE9;duite du cerveau vu dans une microc&#xE9;phalie font d&#xE9;faut. Ici, nous montrons que Magoh, un composant du complexe de jonction exon (EJC), qui lie l&#x26;#39;ARN, contr&#xF4;le de la souris la taille du cortex c&#xE9;r&#xE9;bral en r&#xE9;gulant la division NSC. Magoh haplo-insuffisance provoque une microc&#xE9;phalie raison de l&#x26;#39;&#xE9;puisement INP et l&#x26;#39;apoptose neuronale. D&#xE9;fectueux sous-tend la mitose ces ph&#xE9;notypes, que l&#x26;#39;&#xE9;puisement des composants EJC perturbe l&#x26;#39;orientation du fuseau mitotique et l&#x26;#39;int&#xE9;grit&#xE9;, le nombre de chromosomes et de la stabilit&#xE9; g&#xE9;nomique. In utero exp&#xE9;riences de sauvetage a montr&#xE9; que d&#x26;#39;une fonction cl&#xE9; de Magoh est de contr&#xF4;ler les niveaux de la prot&#xE9;ine LIS1 microc&#xE9;phalie associ&#xE9;e au cours de la neurogen&#xE8;se. Nos r&#xE9;sultats de d&#xE9;couvrir les exigences pour l&#x26;#39;EJC dans le d&#xE9;veloppement du cerveau, de l&#x26;#39;entretien CSN et de la mitose, ce qui ce complexe impliquant dans la pathogen&#xE8;se de microc&#xE9;phalie.

La jonction Exon composant Magoh Complexe Contr&#xF4;les Taille du cerveau par la r&#xE9;glementation Neural division des cellules souches

Gehirnstruktur und Gr&ouml;&szlig;e erfordern genaue Aufteilung der neuralen Stammzellen (NSCs), die erneuern und fortgeschrittene neuronalen Vorl&auml;uferzellen (INPs) und Neuronen zu generieren. Die Faktoren, die NSCs Regeln bleiben weitgehend unverstanden und mechanistische Erkl&auml;rungen wie aberrante NSC Abteilung Ursachen die reduzierten Gehirngr&ouml;&szlig;e in Mikrozephalie gesehen fehlen. Hier zeigen wir, dass Magoh, eine Komponente der Exon Kreuzung komplexe (EJC), die RNA bindet zerebrale kortikale Mausgr&ouml;&szlig;e Kontrollen durch die Regelung des NSC-Abteilung. Magoh Haploinsuffizienz verursacht Mikrozephalie wegen INP Ersch&ouml;pfung und neuronalen Apoptose. Defekte Mitose unterliegt diese Ph&auml;notypen, wie Ersch&ouml;pfung der EJC Komponenten mitotische Spindel Orientierung und Integrit&auml;t, Chromosomenzahl und genomischen Stabilit&auml;t st&ouml;rt. In der Geb&auml;rmutter Rettungs-Experimente zeigten, dass eine wesentliche Funktion der Magoh Ebenen des Mikrozephalie-assoziierten Proteins Lis1 w&auml;hrend Neurogenese gesteuert. Unsere Ergebnisse decken Anforderungen f&uuml;r die EJC bei Gehirnentwicklung, NSC Wartungs- und Mitose, wodurch Nicht&uuml;bernahme der Komplex in der Pathogenese von Mikrozephalie.

Die Exon Kreuzung komplexes Bauteil Magoh Steuerelemente Gehirn Gr&ouml;&szlig;e durch die Regelung des neuronalen Stammzellen-Abteilung.

Dimensioni e struttura del cervello richiede precisa divisione delle cellule neurali staminali (NSCs), che auto-rinnovarsi e generare progenitori neurali intermedi (INPs) e neuroni. I fattori che regolano NSCs rimangono scarsamente comprensibile e meccanicistici spiegazioni aberranti come cause di divisione NSC la dimensione ridotta del cervello vista in microcefalia sono carenti. Qui vi mostriamo che Magoh, un componente dell&#39;esone incrocio complesso (EJC) che lega il RNA, controlla la dimensione corticale cerebrale mouse regolando la divisione NSC. Magoh aploinsufficienza provoca microcefalia a causa della deplezione INP e apoptosi neuronale. Mitosi difettosi soggiace questi fenotipi, come esaurimento delle componenti EJC sconvolge mitotico orientamento e integrit&agrave;, numero cromosomico e stabilit&agrave; genomica. Salvataggio in utero esperimenti hanno mostrato che una funzione chiave di Magoh &egrave; quello di controllare i livelli della proteina associata a microcefalia Lis1 durante la neurogenesi. I nostri risultati scoprono requisiti per la EJC nello sviluppo del cervello, manutenzione NSC e mitosi, implicando quindi questo complesso nella patogenesi della microcefalia.

I controlli di Magoh componente complessa giunzione esone cervello dimensioni regolando la divisione delle cellule staminali neurali.

&#x8133;&#x306E;&#x69CB;&#x9020;&#x3068;&#x30B5;&#x30A4;&#x30BA;&#x306F;&#x3001;&#x4E2D;&#x9593;&#x795E;&#x7D4C;&#x524D;&#x99C6;&#x7D30;&#x80DE;&#xFF08;INPS&#xFF09;&#x3068;&#x30CB;&#x30E5;&#x30FC;&#x30ED;&#x30F3;&#x3092;&#x81EA;&#x5DF1;&#x66F4;&#x65B0;&#x3057;&#x3001;&#x751F;&#x6210;&#x3055;&#x308C;&#x305F;&#x795E;&#x7D4C;&#x5E79;&#x7D30;&#x80DE;&#xFF08;NSC&#xFF09;&#x306E;&#x6B63;&#x78BA;&#x306A;&#x9664;&#x7B97;&#x3092;&#x5FC5;&#x8981;&#x3068;&#x3057;&#x307E;&#x3059;&#x3002; NSC&#x306E;&#x3092;&#x898F;&#x5236;&#x3059;&#x308B;&#x8981;&#x56E0;&#x306F;&#x3088;&#x304F;&#x308F;&#x304B;&#x3063;&#x3066;&#x3044;&#x306A;&#x3044;&#x307E;&#x307E;&#x3067;&#x3042;&#x308A;&#x3001;&#x7570;&#x5E38;&#x306A;NSC&#x90E8;&#x9580;&#x306F;&#x5C0F;&#x982D;&#x75C7;&#x3067;&#x898B;&#x3089;&#x308C;&#x308B;&#x7E2E;&#x5C0F;&#x8133;&#x306E;&#x5927;&#x304D;&#x3055;&#x3092;&#x5F15;&#x304D;&#x8D77;&#x3053;&#x3059;&#x304B;&#x306E;&#x30E1;&#x30AB;&#x30CB;&#x30BA;&#x30E0;&#x306E;&#x8AAC;&#x660E;&#x304C;&#x4E0D;&#x8DB3;&#x3057;&#x3066;&#x3044;&#x308B;&#x3002;&#x3053;&#x3053;&#x3067;&#x306F;&#x3001;Magoh&#x3001;RNA&#x3092;&#x7D50;&#x5408;&#x3059;&#x308B;&#x30A8;&#x30AD;&#x30BD;&#x30F3;&#x30B8;&#x30E3;&#x30F3;&#x30AF;&#x30B7;&#x30E7;&#x200B;&#x200B;&#x30F3;&#x8907;&#x5408;&#x4F53;&#xFF08;EJC&#xFF09;&#x306E;&#x30B3;&#x200B;&#x200B;&#x30F3;&#x30DD;&#x30FC;&#x30CD;&#x30F3;&#x30C8;&#x306F;&#x3001;NSC&#x5206;&#x88C2;&#x3092;&#x8ABF;&#x7BC0;&#x3059;&#x308B;&#x3053;&#x3068;&#x306B;&#x3088;&#x308A;&#x3001;&#x30DE;&#x30A6;&#x30B9;&#x306E;&#x5927;&#x8133;&#x76AE;&#x8CEA;&#x306E;&#x30B5;&#x30A4;&#x30BA;&#x3092;&#x5236;&#x5FA1;&#x3057;&#x3066;&#x3044;&#x308B;&#x3053;&#x3068;&#x3092;&#x793A;&#x3057;&#x3066;&#x3044;&#x307E;&#x3059;&#x3002; Magoh&#x30CF;&#x30D7;&#x30ED;&#x4E0D;&#x5168;&#x306F;&#x3001;INP&#x67AF;&#x6E07;&#x3068;&#x795E;&#x7D4C;&#x7D30;&#x80DE;&#x30A2;&#x30DD;&#x30C8;&#x30FC;&#x30B7;&#x30B9;&#x306E;&#x305F;&#x3081;&#x306B;&#x5C0F;&#x982D;&#x75C7;&#x3092;&#x5F15;&#x304D;&#x8D77;&#x3053;&#x3057;&#x307E;&#x3059;&#x3002;&#x6B20;&#x9665;&#x306E;&#x6709;&#x7CF8;&#x5206;&#x88C2;&#x306E;&#x6839;&#x5E95;&#x306B;&#x3053;&#x308C;&#x3089;&#x306E;&#x8868;&#x73FE;&#x578B;&#x306F;&#x3001;EJC&#x306E;&#x30B3;&#x30F3;&#x30DD;&#x30FC;&#x30CD;&#x30F3;&#x30C8;&#x306E;&#x67AF;&#x6E07;&#x306A;&#x3069;&#x306E;&#x6709;&#x7CF8;&#x5206;&#x88C2;&#x7D21;&#x9318;&#x4F53;&#x306E;&#x914D;&#x5411;&#x6027;&#x3068;&#x6574;&#x5408;&#x6027;&#x3001;&#x67D3;&#x8272;&#x4F53;&#x756A;&#x53F7;&#x3001;&#x30B2;&#x30CE;&#x30E0;&#x306E;&#x5B89;&#x5B9A;&#x6027;&#x3092;&#x7834;&#x58CA;&#x3059;&#x308B;&#x3002;&#x5B50;&#x5BAE;&#x5185;&#x3067;&#x306E;&#x30EC;&#x30B9;&#x30AD;&#x30E5;&#x30FC;&#x5B9F;&#x9A13;&#x306F;Magoh&#x306E;&#x4E3B;&#x8981;&#x306A;&#x6A5F;&#x80FD;&#x306F;&#x3001;&#x795E;&#x7D4C;&#x306E;&#x9593;&#x306B;&#x5C0F;&#x982D;&#x75C7;&#x95A2;&#x9023;&#x30BF;&#x30F3;&#x30D1;&#x30AF;&#x8CEA;LIS1&#x306E;&#x30EC;&#x30D9;&#x30EB;&#x3092;&#x5236;&#x5FA1;&#x3059;&#x308B;&#x3053;&#x3068;&#x3067;&#x3042;&#x308B;&#x3053;&#x3068;&#x3092;&#x793A;&#x3057;&#x305F;&#x3002;&#x6211;&#x3005;&#x306E;&#x7D50;&#x679C;&#x306F;&#x3001;&#x305D;&#x308C;&#x306B;&#x3088;&#x3063;&#x3066;&#x5C0F;&#x982D;&#x75C7;&#x306E;&#x75C5;&#x56E0;&#x306B;&#x3053;&#x306E;&#x8907;&#x5408;&#x4F53;&#x3092;&#x304C;&#x95A2;&#x4E0E;&#x3057;&#x3001;&#x8133;&#x306E;&#x767A;&#x9054;&#x306B;EJC&#x3001;NSC&#x306E;&#x30E1;&#x30F3;&#x30C6;&#x30CA;&#x30F3;&#x30B9;&#x3084;&#x6709;&#x7CF8;&#x5206;&#x88C2;&#x306E;&#x305F;&#x3081;&#x306E;&#x8981;&#x4EF6;&#x3092;&#x660E;&#x3089;&#x304B;&#x306B;&#x3057;&#x307E;&#x3059;&#x3002;

&#x30A8;&#x30AD;&#x30BD;&#x30F3;&#x30B8;&#x30E3;&#x30F3;&#x30AF;&#x30B7;&#x30E7;&#x200B;&#x200B;&#x30F3;&#x8907;&#x5408;&#x30B3;&#x30F3;&#x30DD;&#x30FC;&#x30CD;&#x30F3;&#x30C8;Magoh&#x306F;&#x3001;&#x795E;&#x7D4C;&#x5E79;&#x7D30;&#x80DE;&#x5206;&#x88C2;&#x3092;&#x8ABF;&#x7BC0;&#x3059;&#x308B;&#x3053;&#x3068;&#x306B;&#x3088;&#x308A;&#x3001;&#x8133;&#x306E;&#x30B5;&#x30A4;&#x30BA;&#x3092;&#x5236;&#x5FA1;

&#xB1CC; &#xAD6C;&#xC870;&#xC640; &#xD06C;&#xAE30; self-renew &#xBC0F; &#xC911;&#xAC04; &#xC2E0;&#xACBD; progenitors (INPs) &#xBC0F; &#xC2E0;&#xACBD; &#xC138;&#xD3EC;&#xB97C; &#xC0DD;&#xC131; &#xD558;&#xB294; &#xC2E0;&#xACBD; &#xC904;&#xAE30; &#xC138;&#xD3EC; (NSCs)&#xC758; &#xC815;&#xD655;&#xD55C; &#xBD80;&#xB97C; &#xD544;&#xC694; &#xD569;&#xB2C8;&#xB2E4;. NSCs &#xADDC;&#xC81C; &#xC694;&#xC778; &#xB0A8;&#xC544; &#xC81C;&#xB300;&#xB85C; &#xC774;&#xD574; &#xD558; &#xACE0; &#xAE30;&#xACC4; &#xC5B4;&#xB5BB;&#xAC8C; &#xD0C8; &#xC120; NSC &#xBD80;&#xBB38; &#xC6D0;&#xC778; microcephaly&#xC5D0;&#xC11C; &#xAC10;&#xC18C; &#xB41C; &#xB1CC; &#xD06C;&#xAE30;&#xB294; &#xBD80;&#xC871; &#xD55C; &#xC124;&#xBA85;. &#xC5EC;&#xAE30; &#xC6B0;&#xB9AC;&#xAC00; NSC &#xBD80;&#xBB38; &#xADDC;&#xC81C; &#xD568;&#xC73C;&#xB85C;&#xC368; &#xB9C8;&#xC6B0;&#xC2A4; &#xB300;&#xB1CC; &#xB300;&#xB1CC; &#xD53C; &#xC9C8;&#xC758; &#xD06C;&#xAE30;&#xB97C; &#xC81C;&#xC5B4; Magoh&#xB294; exon &#xC811;&#xC810;&#xC758; &#xBCF5;&#xC7A1; &#xD55C; (EJC) RNA, &#xBC14;&#xC778;&#xB529;&#xD558;&#xB294; &#xAD6C;&#xC131; &#xC694;&#xC18C;&#xB97C; &#xBCF4;&#xC5EC;&#xC90D;&#xB2C8;&#xB2E4;. Magoh haploinsufficiency INP &#xACE0;&#xAC08; &#xBC0F; &#xC2E0;&#xACBD; apoptosis microcephaly&#xB97C; &#xBC1C;&#xC0DD;&#xD569;&#xB2C8;&#xB2E4;. EJC &#xCEF4;&#xD3EC;&#xB10C;&#xD2B8;&#xC758; &#xACE0;&#xAC08; &#xBC29;&#xD574; mitotic &#xC2A4;&#xD540; &#xB4E4; &#xBC29;&#xD5A5; &#xBC0F; &#xBB34;&#xACB0;&#xC131;, &#xC5FC;&#xC0C9;&#xCCB4; &#xC218; &#xBC0F; &#xAC8C;&#xB188; &#xC548;&#xC815;&#xC131;&#xC73C;&#xB85C; &#xACB0;&#xD568;&#xC774; &#xC788;&#xB294; &#xC720;&#xC0AC; &#xBD84;&#xC5F4;&#xC774;&#xC774; &#xACE0;&#xAE30; &#xAE30;&#xCD08;&#xAC00;. Utero&#xC5D0;&#xC11C; &#xAD6C;&#xC870; &#xC2E4;&#xD5D8; Magoh&#xC758; &#xD575;&#xC2EC; &#xAE30;&#xB2A5;&#xC740; &#xC131;&#xCCB4; &#xC911; Lis1 microcephaly &#xAD00;&#xB828; &#xB2E8;&#xBC31;&#xC9C8;&#xC758; &#xC218;&#xC900;&#xC744; &#xC81C;&#xC5B4;&#xB97C; &#xBCF4;&#xC5EC;&#xC8FC;&#xC5C8;&#xB2E4;. &#xC6B0;&#xB9AC;&#xC758; &#xACB0;&#xACFC; &#xBC1D;&#xD788;&#xAE30; &#xB450;&#xB1CC; &#xAC1C;&#xBC1C;, &#xAD6D;&#xAC00; &#xC548;&#xC804; &#xBCF4;&#xC7A5; &#xD68C;&#xC758; &#xC720;&#xC9C0; &#xBCF4;&#xC218; &#xBC0F; &#xC720;&#xC0AC; &#xBD84;&#xC5F4;, EJC &#xD568;&#xC73C;&#xB85C;&#xC368; &#xC5F0;&#xB8E8; microcephaly pathogenesis&#xC758;&#xC774; &#xBCF5;&#xC7A1; &#xD55C;&#xC5D0; &#xB300; &#xD55C; &#xC694;&#xAD6C; &#xC0AC;&#xD56D;.

&#xC2E0;&#xACBD; &#xC904;&#xAE30; &#xC138;&#xD3EC; &#xBD84;&#xC5F4;&#xC744; &#xC870;&#xC808; &#xD558; &#xC5EC; &#xB1CC; &#xD06C;&#xAE30;&#xC758; exon &#xC811;&#xD569; &#xBCF5;&#xC7A1; &#xD55C; &#xAD6C;&#xC131; &#xC694;&#xC18C; Magoh &#xCEE8;&#xD2B8;&#xB864;.

La estructura del cerebro y el tama&#xF1;o requieren divisi&#xF3;n precisa de las c&#xE9;lulas madre neurales (NSC), que se auto-renovarse y generar intermedios progenitores neurales (INPS) y las neuronas. Los factores que regulan NSCs siguen siendo poco conocidos, y las explicaciones mecanicistas de la forma aberrante de la divisi&#xF3;n Consejo de Seguridad Nacional hace que el tama&#xF1;o del cerebro se ve en la reducci&#xF3;n microcefalia faltan. Aqu&#xED; nos muestran que Magoh, un componente del complejo de uni&#xF3;n ex&#xF3;n (EJC) que se une ARN, controla rat&#xF3;n cortical cerebral mediante la regulaci&#xF3;n de tama&#xF1;o NSC divisi&#xF3;n. Magoh haploinsuficiencia causas de la microcefalia debido al agotamiento de INP y la apoptosis neuronal. Defectuosos subyace en la mitosis estos fenotipos, como el agotamiento de los componentes del EJC altera la orientaci&#xF3;n huso mit&#xF3;tico y la integridad, el n&#xFA;mero de cromosomas y la estabilidad gen&#xF3;mica. En el &#xFA;tero de rescate experimentos mostraron que una funci&#xF3;n clave de Magoh es controlar los niveles de la prote&#xED;na de LIS1 microcefalia asociada durante la neurog&#xE9;nesis. Nuestros resultados sugieren que no los requisitos para la EJC en el desarrollo cerebral, el mantenimiento del NSC y la mitosis, lo que implica este complejo en la patog&#xE9;nesis de la microcefalia.

El Magoh uni&#xF3;n ex&#xF3;n componentes complejos controles Tama&#xF1;o del cerebro por la Divisi&#xF3;n de Regulaci&#xF3;n de c&#xE9;lulas madre neurales

Melanoblasts are a population of neural crest-derived cells that generate the pigment-producing cells of our body. Defective melanoblast development and function underlies many disorders including Waardenburg syndrome and melanoma. Understanding the genetic regulation of melanoblast development will help elucidate the etiology of these and other neurocristopathies. Here we demonstrate that Magoh, a component of the exon junction complex, is required for normal melanoblast development. Magoh haploinsufficient mice are hypopigmented and exhibit robust genetic interactions with the transcription factor, Sox10. These phenotypes are caused by a marked reduction in melanoblast number beginning at mid-embryogenesis. Strikingly, while Magoh haploinsufficiency severely reduces epidermal melanoblasts, it does not significantly affect the number of dermal melanoblasts. These data indicate Magoh impacts melanoblast development by disproportionately affecting expansion of epidermal melanoblast populations. We probed the cellular basis for melanoblast reduction and discovered that Magoh mutant melanoblasts do not undergo increased apoptosis, but instead are arrested in mitosis. Mitotic arrest is evident in both Magoh haploinsufficient embryos and in Magoh siRNA treated melanoma cell lines. Together our findings indicate that Magoh-regulated proliferation of melanoblasts in the dermis may be critical for production of epidermally-bound melanoblasts. Our results point to a central role for Magoh in melanocyte development.

The EJC component Magoh regulates proliferation and expansion of neural crest-derived melanocytes.

Cell motility is essential for embryonic development and physiological processes such as the immune response, but also contributes to pathological conditions such as tumor progression and inflammation. However, our understanding of the mechanisms underlying migratory processes is incomplete. Drosophila border cells provide a powerful genetic model to identify the roles of genes that contribute to cell migration.

Genetic interaction screens identify a role for hedgehog signaling in Drosophila border cell migration.

We analyzed four families that presented with a similar condition characterized by congenital microcephaly, intellectual disability, progressive cerebral atrophy, and intractable seizures. We show that recessive mutations in the ASNS gene are responsible for this syndrome. Two of the identified missense mutations dramatically reduce ASNS protein abundance, suggesting that the mutations cause loss of function. Hypomorphic Asns mutant mice have structural brain abnormalities, including enlarged ventricles and reduced cortical thickness, and show deficits in learning and memory mimicking aspects of the patient phenotype. ASNS encodes asparagine synthetase, which catalyzes the synthesis of asparagine from glutamine and aspartate. The neurological impairment resulting from ASNS deficiency may be explained by asparagine depletion in the brain or by accumulation of aspartate/glutamate leading to enhanced excitability and neuronal damage. Our study thus indicates that asparagine synthesis is essential for the development and function of the brain but not for that of other organs.

Deficiency of asparagine synthetase causes congenital microcephaly and a progressive form of encephalopathy.

Magoh encodes a core component of the exon junction complex (EJC), which binds mRNA and regulates mRNA metabolism. Magoh is highly expressed in proliferative tissues during development. EJC components have been implicated in several developmental disorders including TAR syndrome, Richieri-Costa-Pereira syndrome, and intellectual disability. Existing germline null Magoh mice are embryonic lethal as homozygotes and perinatal lethal as heterozygotes, precluding detailed analysis of embryonic and postnatal functions. Here, we report the generation of a new genetic tool to dissect temporal and tissue-specific roles for Magoh in development and adult homeostasis. This Magoh conditional allele has two loxP sites flanking the second exon. Ubiquitous Cre-mediated deletion of the floxed allele in a heterozygous mouse (Magoh(del/+) ) causes 50% reduction of both Magoh mRNA and protein. Magoh(del/+) mice exhibit both microcephaly and hypopigmentation, thus phenocopying germline haploinsufficient Magoh mice. Using Emx1-Cre, we further show that conditional Magoh deletion in neural progenitors during embryonic development also causes microcephaly. We anticipate this novel conditional allele will be a valuable tool for assessing tissue-specific roles for Magoh in mammalian development and postnatal processes. genesis 00:1-7. © 2014 Wiley Periodicals, Inc.

Article	Year
A new trick for Cyclin-Cdk: activation of STAT. Developmental cell\| PubMed ID: 12586057	2003
Activated signal transducer and activator of transcription (STAT) 3: localization in focal adhesions and function in ovarian cancer cell motility. Cancer research\| PubMed ID: 15150111	2004
Requirement for JAK/STAT signaling throughout border cell migration in Drosophila. Development (Cambridge, England)\| PubMed ID: 16000386	2005
The genetic regulation of pigment cell development. Advances in experimental medicine and biology\| PubMed ID: 17076280	2006
A sensitized mutagenesis screen identifies Gli3 as a modifier of Sox10 neurocristopathy. Human molecular genetics\| PubMed ID: 18397875	2008
The secreted metalloprotease ADAMTS20 is required for melanoblast survival. PLoS genetics\| PubMed ID: 18454205	2008
ADAMTS metalloproteases generate active versican fragments that regulate interdigital web regression. Developmental cell\| PubMed ID: 19922873	2009
The exon junction complex component Magoh controls brain size by regulating neural stem cell division. Nature neuroscience\| PubMed ID: 20364144	2010
The EJC component Magoh regulates proliferation and expansion of neural crest-derived melanocytes. Developmental biology\| PubMed ID: 23333945	2013
Genetic interaction screens identify a role for hedgehog signaling in Drosophila border cell migration. Developmental dynamics : an official publication of the American Association of Anatomists\| PubMed ID: 23335293	2013
Deficiency of asparagine synthetase causes congenital microcephaly and a progressive form of encephalopathy. Neuron\| PubMed ID: 24139043	2013
Generation of a Magoh conditional allele in mice. Genesis (New York, N.Y. : 2000)\| PubMed ID: 24771530	2014

Debra L. Silver

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