<em>Ex Utero</em> Electroporation and Organotypic Slice Culture of Mouse Hippocampal Tissue

Mouse genetics offers a powerful tool determining the role of specific genes during development. Analyzing the resulting phenotypes by immunohistochemical ...

Time-lapse Confocal Imaging of Migrating Neurons in Organotypic Slice Culture of Embryonic Mouse Brain Using <em>In Utero</em> Electroporation

In utero electroporation is a rapid and powerful approach to study the process of radial migration in the cerebral cortex of developing mouse embryos. It ...

University of Ulm

Ulm University

The ErbB2 (Her2) proto-oncogene encodes a receptor tyrosine kinase, which is frequently amplified and overexpressed in human tumors. ErbB2 provides the target for a novel and effective antibody-based therapy (Trastuzumab/Herceptin) used for the treatment of mammary carcinomas. However, cardiomyopathies develop in a proportion of patients treated with Trastuzumab, and the incidence of such complications is increased by combination with standard chemotherapy. Gene ablation studies have previously demonstrated that the ErbB2 receptor, together with its coreceptor ErbB4 and the ligand Neuregulin-1, are essential for normal development of the heart ventricle. We use here Cre-loxP technology to mutate ErbB2 specifically in ventricular cardiomyocytes. Conditional mutant mice develop a severe dilated cardiomyopathy, with signs of cardiac dysfunction generally appearing by the second postnatal month. We infer that signaling from the ErbB2 receptor, which is enriched in T-tubules in cardiomyocytes, is crucial for adult heart function. Conditional ErbB2 mutant mice provide a model of dilated cardiomyopathy. In particular, they will allow a rigorous assessment of the role of ErbB2 in the heart and provide insight into the molecular mechanisms that underlie the adverse effects of anti-ErbB2 antibodies.

Conditional mutation of the ErbB2 (HER2) receptor in cardiomyocytes leads to dilated cardiomyopathy.

&#x795E;&#x7ECF;&#x548C;&#x8840;&#x7BA1;&#x7684;&#x5206;&#x652F;&#x7684;&#x7ED3;&#x6784;&#xFF0C;&#x4F46;&#x4E0D;&#x6E05;&#x695A;&#x662F;&#x5426;&#x8BBE;&#x7ACB;&#x4E86;&#x72EC;&#x7ACB;&#x6216;&#x534F;&#x8C03;&#x7684;&#x5176;&#x5206;&#x652F;&#x6A21;&#x5F0F;&#x3002;&#x5728;&#x8FD9;&#x91CC;&#x6211;&#x4EEC;&#x5C55;&#x793A;&#x4E0E;&#x5C0F;&#x9F20;&#x80DA;&#x80CE;&#x80A2;&#x4F53;&#x76AE;&#x80A4;&#x5916;&#x5468;&#x795E;&#x7ECF;&#x7279;&#x522B;&#x5BF9;&#x9F50;&#x52A8;&#x8109;&#xFF0C;&#x4F46;&#x4E0D;&#x662F;&#x8109;&#x3002;&#x6D88;&#x9664;&#x611F;&#x5B98;&#x5468;&#x56F4;&#x795E;&#x7ECF;&#x6216;&#x96EA;&#x65FA;&#x7EC6;&#x80DE;&#x7684;&#x7A81;&#x53D8;&#x9632;&#x6B62;&#x9002;&#x5F53;&#x7684; arteriogenesis&#xFF0C;&#x867D;&#x7136;&#x90A3;&#x4E9B;&#x74E6;&#x89E3;&#x795E;&#x7ECF;&#x4FDD;&#x6301;&#x52A8;&#x8109;&#x8BEF;&#x8F74;&#x7A81;&#x7684;&#x5BF9;&#x9F50;&#x65B9;&#x5F0F;&#x3002;&#x4F53;&#x5916;&#xFF0C;&#x611F;&#x89C9;&#x795E;&#x7ECF;&#x5143;&#x6216;&#x96EA;&#x65FA;&#x7EC6;&#x80DE;&#x53EF;&#x4EE5;&#x8BF1;&#x4F7F;&#x80DA;&#x80CE;&#x8840;&#x7BA1;&#x5185;&#x76AE;&#x7EC6;&#x80DE;&#xFF0C;&#x52A8;&#x8109;&#x6807;&#x8BB0;&#x8868;&#x8FBE;&#x5F0F;&#xFF0C;VEGF(164/120) &#x662F;&#x5FC5;&#x8981;&#x7684;&#x4E0D;&#x8DB3;&#x4EE5;&#x8C03;&#x89E3;&#x8FD9;&#x79CD;&#x611F;&#x5E94;&#x3002;&#x8FD9;&#x4E9B;&#x6570;&#x636E;&#x8868;&#x660E;&#x5916;&#x5468;&#x795E;&#x7ECF;&#x63D0;&#x4F9B;&#x4E00;&#x4E2A;&#x6A21;&#x677F;&#xFF0C;&#x5B83;&#x51B3;&#x5B9A;&#x5728;&#x76AE;&#x80A4;&#x4E0A;&#xFF0C;&#x901A;&#x8FC7;&#x672C;&#x5730;&#x5206;&#x6CCC; VEGF &#x7684;&#x8840;&#x7BA1;&#x5206;&#x652F;&#x548C;&#x52A8;&#x8109;&#x5206;&#x5316;&#x7684;&#x5668;&#x5B98;&#x578B;&#x6A21;&#x5F0F;&#x3002;

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Nerves and blood vessels are branched structures, but whether their branching patterns are established independently or coordinately is not clear. Here we show that arteries, but not veins, are specifically aligned with peripheral nerves in embryonic mouse limb skin. Mutations that eliminate peripheral sensory nerves or Schwann cells prevent proper arteriogenesis, while those that disorganize the nerves maintain the alignment of arteries with misrouted axons. In vitro, sensory neurons or Schwann cells can induce arterial marker expression in isolated embryonic endothelial cells, and VEGF(164/120) is necessary and sufficient to mediate this induction. These data suggest that peripheral nerves provide a template that determines the organotypic pattern of blood vessel branching and arterial differentiation in the skin, via local secretion of VEGF.

Sensory nerves determine the pattern of arterial differentiation and blood vessel branching in the skin.

Les nerfs et les vaisseaux sanguins sont des structures ramifi&#xE9;es, mais si leurs patrons de ramification sont &#xE9;tablis de mani&#xE8;re ind&#xE9;pendante ou coordonn&#xE9;e n&#x26;#39;est pas clair. Ici, nous montrons que les art&#xE8;res, veines, mais pas sp&#xE9;cifiquement align&#xE9; avec les nerfs p&#xE9;riph&#xE9;riques dans la peau de souris branche embryonnaire. Les mutations qui &#xE9;liminent nerfs sensitifs p&#xE9;riph&#xE9;riques ou les cellules de Schwann &#xE9;viter art&#xE9;riogen&#xE8;se bon, tandis que ceux qui d&#xE9;sorganisent les nerfs maintenir l&#x26;#39;alignement des art&#xE8;res avec les axones d&#xE9;rout&#xE9;s. In vitro, les neurones sensoriels ou les cellules de Schwann peuvent induire l&#x26;#39;expression du marqueur art&#xE9;riel dans isol&#xE9;es embryonnaires des cellules endoth&#xE9;liales, et le VEGF (164/120) est n&#xE9;cessaire et suffisant de rem&#xE9;dier &#xE0; ce induction. Ces donn&#xE9;es sugg&#xE8;rent que les nerfs p&#xE9;riph&#xE9;riques de fournir un mod&#xE8;le qui d&#xE9;termine le mod&#xE8;le organotypique d&#x26;#39;un vaisseau sanguin ramification art&#xE9;rielle et de la diff&#xE9;renciation dans la peau, via la s&#xE9;cr&#xE9;tion locale de VEGF.

Les nerfs sensoriels D&#xE9;terminer le sch&#xE9;ma de diff&#xE9;renciation art&#xE9;rielle et des vaisseaux sanguins &#xC9;claircie dans la peau

Sensorischen Nerven bestimmen das Muster der Differenzierung und arteriellen Blutgef&#xE4;&#xDF;es Verzweigung in der Haut.

Nervi e vasi sanguigni sono strutture ramificate, ma non &egrave; chiaro se i loro modelli di ramificazione sono stabiliti indipendentemente o coordinately. Qui vi mostriamo che le arterie, ma non le vene, specificamente sono allineate con i nervi periferici in pelle dell&#39;arto embrionali del mouse. Mutazioni che eliminano i nervi sensoriali periferici o cellule di Schwann prevenire arteriogenesis corretta, mentre quelli che disorganizzare i nervi mantenere l&#39;allineamento delle arterie con assoni misrouted. I neuroni in vitro, sensoriali o cellule di Schwann possono indurre espressione arteriosa marcatore in cellule endoteliali embrionali isolate, e VEGF(164/120) &egrave; necessario e sufficiente per mediare questa induzione. Questi dati suggeriscono che i nervi periferici forniscano un modello che determina il modello organotypic del vaso sanguigno arterioso e ramificazione differenziazione della pelle, attraverso la secrezione locale di VEGF.

Nervi sensoriali determinano il pattern di differenziazione arterioso e vasi sanguigni ramificazione della pelle.

&#x795E;&#x7D4C;&#x3084;&#x8840;&#x7BA1;&#x304C;&#x5206;&#x5C90;&#x3057;&#x305F;&#x69CB;&#x9020;&#x3067;&#x3042;&#x308B;&#x304C;&#x3001;&#x305D;&#x306E;&#x5206;&#x5C90;&#x30D1;&#x30BF;&#x30FC;&#x30F3;&#x304C;&#x72EC;&#x7ACB;&#x3057;&#x3066;&#x3001;&#x307E;&#x305F;&#x306F;&#x5354;&#x8ABF;&#x7684;&#x306B;&#x78BA;&#x7ACB;&#x3055;&#x308C;&#x3066;&#x3044;&#x308B;&#x304B;&#x3069;&#x3046;&#x304B;&#x306F;&#x660E;&#x78BA;&#x3067;&#x306F;&#x3042;&#x308A;&#x307E;&#x305B;&#x3093;&#x3002;&#x3053;&#x3053;&#x3067;&#x306F;&#x3001;&#x52D5;&#x8108;&#x3067;&#x306F;&#x306A;&#x304F;&#x3001;&#x9759;&#x8108;&#x306F;&#x3001;&#x7279;&#x306B;&#x30DE;&#x30A6;&#x30B9;&#x80CE;&#x5150;&#x56DB;&#x80A2;&#x306E;&#x76AE;&#x819A;&#x306E;&#x672B;&#x68A2;&#x795E;&#x7D4C;&#x306E;&#x4F4D;&#x7F6E;&#x304C;&#x5408;&#x3063;&#x3066;&#x3044;&#x308B;&#x3053;&#x3068;&#x3092;&#x793A;&#x3057;&#x3066;&#x3044;&#x307E;&#x3059;&#x3002;&#x795E;&#x7D4C;&#x7D44;&#x7E54;&#x3092;&#x58CA;&#x3059;&#x3082;&#x306E;&#x304C;&#x8AA4;&#x3063;&#x3066;&#x30EB;&#x30FC;&#x30C6;&#x30A3;&#x30F3;&#x30B0;&#x8EF8;&#x7D22;&#x3068;&#x52D5;&#x8108;&#x306E;&#x30A2;&#x30E9;&#x30A4;&#x30E1;&#x30F3;&#x30C8;&#x3092;&#x7DAD;&#x6301;&#x3057;&#x306A;&#x304C;&#x3089;&#x3001;&#x672B;&#x68A2;&#x611F;&#x899A;&#x795E;&#x7D4C;&#x3084;&#x30B7;&#x30E5;&#x30EF;&#x30F3;&#x7D30;&#x80DE;&#x3092;&#x6392;&#x9664;&#x3059;&#x308B;&#x5909;&#x7570;&#x306F;&#x3001;&#x9069;&#x5207;&#x306A;&#x52D5;&#x8108;&#x5F62;&#x6210;&#x3092;&#x9632;&#x3050;&#x3053;&#x3068;&#x304C;&#x3067;&#x304D;&#x307E;&#x3059;&#x3002; in vitro&#x3067;&#x3001;&#x611F;&#x899A;&#x795E;&#x7D4C;&#x7D30;&#x80DE;&#x3084;&#x30B7;&#x30E5;&#x30EF;&#x30F3;&#x7D30;&#x80DE;&#x306F;&#x3001;&#x5358;&#x96E2;&#x3055;&#x308C;&#x305F;&#x80DA;&#x306E;&#x5185;&#x76AE;&#x7D30;&#x80DE;&#x3001;&#x52D5;&#x8108;&#x30DE;&#x30FC;&#x30AB;&#x30FC;&#x306E;&#x767A;&#x73FE;&#x3092;&#x8A98;&#x5C0E;&#x3059;&#x308B;&#x3053;&#x3068;&#x304C;&#x3067;&#x304D;&#x3001;VEGF&#xFF08;164/120&#xFF09;&#x306F;&#x3001;&#x5FC5;&#x8981;&#x306B;&#x5FDC;&#x3058;&#x3066;&#x3001;&#x3053;&#x306E;&#x8A98;&#x5C0E;&#x3092;&#x4EF2;&#x4ECB;&#x3059;&#x200B;&#x200B;&#x308B;&#x306E;&#x306B;&#x5341;&#x5206;&#x3067;&#x3042;&#x308B;&#x3002;&#x3053;&#x308C;&#x3089;&#x306E;&#x30C7;&#x30FC;&#x30BF;&#x306F;&#x3001;&#x672B;&#x68A2;&#x795E;&#x7D4C;&#x306F;&#x3001;VEGF&#x306E;&#x30ED;&#x30FC;&#x30AB;&#x30EB;&#x5206;&#x6CCC;&#x3092;&#x4ECB;&#x3057;&#x3066;&#x3001;&#x8840;&#x7BA1;&#x5206;&#x5C90;&#x3068;&#x76AE;&#x819A;&#x306E;&#x8840;&#x7BA1;&#x5206;&#x5316;&#x306E;&#x5668;&#x5B98;&#x30D1;&#x30BF;&#x30FC;&#x30F3;&#x3092;&#x6C7A;&#x5B9A;&#x3059;&#x308B;&#x30C6;&#x30F3;&#x30D7;&#x30EC;&#x30FC;&#x30C8;&#x3092;&#x63D0;&#x4F9B;&#x3059;&#x308B;&#x3053;&#x3068;&#x3092;&#x304A;&#x52E7;&#x3081;&#x3057;&#x307E;&#x3059;&#x3002;

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&#xC2E0;&#xACBD; &#xBC0F; &#xD608;&#xAD00; &#xBD84;&#xAE30; &#xAD6C;&#xC870;, &#xD558;&#xC9C0;&#xB9CC; &#xB3C5;&#xB9BD;&#xC801;&#xC73C;&#xB85C; &#xB610;&#xB294; coordinately&#xC758; &#xBD84;&#xAE30; &#xD328;&#xD134;&#xC744; &#xC124;&#xB9BD; &#xD558;&#xB294; &#xC5EC;&#xBD80;&#xB97C; &#xD558;&#xB294; &#xAC83;&#xC740; &#xBD84;&#xBA85; &#xD569;&#xB2C8;&#xB2E4;. &#xC5EC;&#xAE30; &#xC6B0;&#xB9AC;&#xAC00; &#xB3D9;&#xB9E5;, &#xD558;&#xC9C0;&#xB9CC; &#xD558;&#xC9C0;&#xC758; &#xC815; &#xB9E5;, &#xBC30;&#xC544; &#xB9C8;&#xC6B0;&#xC2A4; &#xB2E4;&#xB9AC; &#xD53C;&#xBD80; &#xB9D0; &#xCD08; &#xC2E0;&#xACBD;&#xC73C;&#xB85C; &#xC815;&#xB82C; &#xAD6C;&#xCCB4;&#xC801;&#xC73C;&#xB85C; &#xBCF4;&#xC5EC;&#xC90D;&#xB2C8;&#xB2E4;. &#xADF8; &#xC2E0;&#xACBD; disorganize &#xD658;&#xACBD;&#xB41C; axons&#xB85C; &#xB3D9;&#xB9E5;&#xC758; &#xC815;&#xB82C;&#xC744; &#xC720;&#xC9C0; &#xD558;&#xB294; &#xB3D9;&#xC548; &#xBCC0;&#xC774; &#xB9D0; &#xCD08; &#xAC10;&#xAC01; &#xC2E0;&#xACBD; &#xB610;&#xB294; Schwann &#xC138;&#xD3EC;&#xB97C; &#xC81C;&#xAC70; &#xD558;&#xB294; &#xC801;&#xC808; &#xD55C; arteriogenesis&#xB97C; &#xBC29;&#xC9C0; &#xD569;&#xB2C8;&#xB2E4;. &#xC0DD;&#xCCB4; &#xC678;&#xC5D0;&#xC11C;, &#xAC10;&#xAC01; &#xC2E0;&#xACBD; &#xC138;&#xD3EC; &#xB098; Schwann &#xC138;&#xD3EC; &#xACA9;&#xB9AC; &#xB41C; &#xBC30;&#xC544; &#xB0B4; &#xD53C; &#xC138;&#xD3EC;&#xC5D0;&#xC11C; &#xB3D9;&#xB9E5; &#xB9C8;&#xCEE4; &#xC2DD;&#xC744; &#xC77C;&#xC73C;&#xD0AC; &#xC218; &#xBC0F; VEGF(164/120)&#xAC00; &#xD544;&#xC694; &#xD558; &#xACE0;&#xC774; &#xC720;&#xB3C4; &#xC911;&#xC7AC; &#xD558;&#xB294; &#xB370; &#xCDA9;&#xBD84; &#xD569;&#xB2C8;&#xB2E4;. &#xC774;&#xB7EC;&#xD55C; &#xB370;&#xC774;&#xD130; &#xC8FC;&#xBCC0; &#xC2E0;&#xACBD; VEGF&#xC758; &#xC9C0;&#xBC29; &#xBD84; &#xBE44;&#xB97C; &#xD1B5;&#xD574; &#xD53C;&#xBD80;&#xC5D0;&#xC11C; &#xD608;&#xAD00; &#xBC0F; &#xB3D9;&#xB9E5; &#xBD84;&#xAE30; &#xCC28;&#xBCC4;&#xD654;&#xC758; organotypic &#xD328;&#xD134;&#xC744; &#xACB0;&#xC815; &#xD558;&#xB294; &#xD15C;&#xD50C;&#xB9BF;&#xC744; &#xC81C;&#xACF5; &#xD558;&#xB294; &#xAC83;&#xC774; &#xC88B;&#xC2B5;&#xB2C8;&#xB2E4;.

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Los nervios y los vasos sangu&#xED;neos son estructuras ramificadas, pero si sus patrones de ramificaci&#xF3;n se establecen de forma independiente o de forma coordinada no es clara. Aqu&#xED; nos muestran que las arterias, venas, pero no est&#xE1;n espec&#xED;ficamente alineadas con los nervios perif&#xE9;ricos en la piel embrionaria del miembro del rat&#xF3;n. Las mutaciones que eliminan los nervios sensoriales perif&#xE9;ricos o c&#xE9;lulas de Schwann prevenir arteriog&#xE9;nesis adecuada, mientras que los que desorganizan los nervios mantener la alineaci&#xF3;n de las arterias con los axones mal encaminados. In vitro, las neuronas sensoriales o las c&#xE9;lulas de Schwann puede inducir la expresi&#xF3;n de marcadores arterial en las c&#xE9;lulas endoteliales aisladas de embriones, y VEGF (164/120) es necesario y suficiente para mediar en esta inducci&#xF3;n. Estos datos sugieren que los nervios perif&#xE9;ricos proporcionar una plantilla que determina el patr&#xF3;n de organot&#xED;pico vaso sangu&#xED;neo ramificaci&#xF3;n arterial y la diferenciaci&#xF3;n en la piel, a trav&#xE9;s de la secreci&#xF3;n local de VEGF.

Los nervios sensoriales determinar el patr&#xF3;n de diferenciaci&#xF3;n arterial y los vasos sangu&#xED;neos de ramificaci&#xF3;n en la piel

Neurons of the dorsal horn integrate and relay sensory information and arise during development in the dorsal spinal cord, the alar plate. Class A and B neurons emerge in the dorsal and ventral alar plate, differ in their dependence on roof plate signals for specification, and settle in the deep and superficial dorsal horn, respectively. We show here that the basic helix-loop-helix (bHLH) gene Olig3 is expressed in progenitor cells that generate class A (dI1-dI3) neurons and that Olig3 is an important factor in the development of these neuronal cell types. In Olig3 mutant mice, the development of class A neurons is impaired; dI1 neurons are generated in reduced numbers, whereas dI2 and dI3 neurons are misspecified and assume the identity of class B neurons. Conversely, Olig3 represses the emergence of class B neurons in the chick spinal cord. We conclude that Olig3 expression distinguishes the two major classes of progenitors in the dorsal spinal cord and determines the distinct specification program of class A neurons.

The bHLH factor Olig3 coordinates the specification of dorsal neurons in the spinal cord.

The dorsal spinal cord processes somatosensory information and relays it to higher brain centers and to motoneurons in the ventral spinal horn. These functions reside in a large number of distinct sensory interneurons that are organized in specific laminae within the dorsal spinal horn. Homeodomain and bHLH transcription factors can control the development of neuronal cell types in the dorsal horn. Here, we demonstrate that the murine homeodomain transcription factor Gbx1 is expressed specifically in a subset of Lbx1(+) (class B) neurons in the dorsal horn. Expression of Gbx1 in the dorsal spinal cord depends on Lbx1 function. Immunohistological analyses revealed that Gbx1 identifies a distinct population of late-born, Lhx1/5(+), Pax2(+) neurons. In the perinatal period as well as in the adult spinal cord, Gbx1 marks a subpopulation of GABAergic neurons. The expression of Gbx1 suggests that it controls development of a specific subset of GABAergic neurons in the dorsal horn of the spinal cord.

The homeodomain transcription factor Gbx1 identifies a subpopulation of late-born GABAergic interneurons in the developing dorsal spinal cord.

Neuregulins (NRGs) comprise a large family of EGF-like signaling molecules involved in cell-cell communication during development and disease. The neuregulin family of ligands has four members: NRG1, NRG2, NRG3, and NRG4. Relatively little is known about the biological functions of the NRG2, 3, and 4 proteins. In contrast, the NRG1 proteins have been demonstrated to play important roles during the development of the nervous system, heart, and mammary glands. For example, NRG1 has essential functions in the development of neural crest cells and some of their major derivatives, like Schwann cells and sympathetic neurons. NRG1 controls the trabeculation of the myocardial musculature and the ductal differentiation of the mammary epithelium. Moreover, there is emerging evidence for the involvement of NRG signals in the development and function of several other organ systems, and in human disease, including breast cancer and schizophrenia. Many different isoforms of the Neuregulin-1 gene are synthesized. Such isoforms differ in their tissue-specific expression patterns and their biological activities, thereby contributing to the great diversity of the in vivo functions of NRG1. Neuregulins transmit their signals to target cells by interacting with transmembrane tyrosine kinase receptors of the ErbB family. This family includes four members, the epidermal growth factor receptor (EGF-R, ErbB1, ErbB2, ErbB3, and ErbB4). Receptor-ligand interaction induces the heterodimerization of receptor monomers, which in turn results in the activation of intracellular signaling cascades and the induction of cellular responses including proliferation, migration, differentiation, and survival or apoptosis. In vivo, functional NRG1 receptors are heterodimers composed of ErbB2 with either an ErbB3, or ErbB4 molecule. The tissue-specific distribution of the different receptor types further contributes to the diversity and specificity of the biological functions of this signaling pathway. It is a typical feature of the Neuregulin-1/ErbB signaling pathway to control sequential steps during the development of a particular organ system. For example, this pathway functions in early precursor proliferation, maturation, as well as in the myelination of Schwann cells. The systematic analysis of genetic models that have been established by the help of conventional as well as conditional gene targeting strategies in mice was instrumental for the uncovering of the multitude of biological functions of this signaling system. In this review the basic biology of the Neuregulin-1/ErbB system and how it relates to the in vivo functions were discussed with special emphasis to transgenic techniques in mice.

The neuregulin-I/ErbB signaling system in development and disease.

Only very few left/right asymmetrically expressed genes are known in the mammalian embryo. In a screen for novel factors we identified the gene encoding the neuropeptide Galanin in mouse. At embryonic day (E) 8.5 asymmetric mRNA transcription was found in the left half of the linear heart tube. During heart looping and morphogenesis expression became restricted to the atrio-ventricular (AV) canal, followed by specific staining of the AV-node and AV-rings in the four-chambered heart. Expression was inverted in inv/inv and randomized in homozygous iv mutant embryos. Left-sided heart-specific transcription of mouse Gal thus should be controlled by the left-right pathway. The asymmetric pattern was retained in cryptic mutant embryos, in which the Nodal signaling cascade is disrupted. Surprisingly, Pitx2c was found to be expressed in 50% of cryptic mutant hearts as well, suggesting that some aspects of asymmetric gene expression in the heart are independent of cryptic.

Left-asymmetric expression of Galanin in the linear heart tube of the mouse embryo is independent of the nodal co-receptor gene cryptic.

Regulation of energy homeostasis is mainly mediated by factors in the hypothalamus and the brainstem. Understanding these regulatory mechanisms is of great clinical relevance in the treatment of obesity and related diseases. The homeobox gene Sax2 is expressed predominantly in the brainstem, in the vicinity of serotonergic neurons, and in the ventral neural tube starting during early development. Previously, we have shown that the loss of function of the Sax2 gene in mouse causes growth retardation starting at birth and a high rate of postnatal lethality, as well as a dramatic metabolic phenotype. To further define the role of Sax2 in energy homeostasis, age-matched adult wild-type, Sax2 heterozygous and null mutant animals were exposed to a high-fat diet. Although food uptake among the different groups was comparable, Sax2 null mutants fed a high-fat diet exhibited a significantly lower weight gain compared to control animals. Unlike their counterparts, Sax2 null mutants did not develop insulin resistance and exhibited significantly lower leptin levels under both standard chow and high-fat diet conditions. Furthermore, neuropeptide Y, an important regulator of energy homeostasis, was significantly decreased in the forebrain of Sax2 null mutants on a high-fat diet. These data strongly suggest a critical role for Sax2 gene expression in diet-induced obesity. Sax2 gene expression may be required to allow the coordinated crosstalk of factors involved in the maintenance of energy homeostasis, possibly regulating the transcription of specific factors involved in energy balance.

Ablation of Sax2 gene expression prevents diet-induced obesity.

Dorsal spinal cord neurons receive and integrate somatosensory information provided by neurons located in dorsal root ganglia. Here we demonstrate that dorsal spinal neurons require the Krüppel-C(2)H(2) zinc-finger transcription factor Bcl11a for terminal differentiation and morphogenesis. The disrupted differentiation of dorsal spinal neurons observed in Bcl11a mutant mice interferes with their correct innervation by cutaneous sensory neurons. To understand the mechanism underlying the innervation deficit, we characterized changes in gene expression in the dorsal horn of Bcl11a mutants and identified dysregulated expression of the gene encoding secreted frizzled-related protein 3 (sFRP3, or Frzb). Frzb mutant mice show a deficit in the innervation of the spinal cord, suggesting that the dysregulated expression of Frzb can account in part for the phenotype of Bcl11a mutants. Thus, our genetic analysis of Bcl11a reveals essential functions of this transcription factor in neuronal morphogenesis and sensory wiring of the dorsal spinal cord and identifies Frzb, a component of the Wnt pathway, as a downstream acting molecule involved in this process.

Bcl11a is required for neuronal morphogenesis and sensory circuit formation in dorsal spinal cord development.

Mitogen-activated protein kinase-activated protein (MAPKAP) kinase 5 (MK5) deficiency is associated with reduced extracellular signal-regulated kinase 3 (ERK3) (mitogen-activated protein kinase 6) levels, hence we utilized the MK5 knockout mouse model to analyze the physiological functions of the ERK3/MK5 signaling module. MK5-deficient mice displayed impaired dendritic spine formation in mouse hippocampal neurons in vivo. We performed large-scale interaction screens to understand the neuronal functions of the ERK3/MK5 pathway and identified septin7 (Sept7) as a novel interacting partner of ERK3. ERK3/MK5/Sept7 form a ternary complex, which can phosphorylate the Sept7 regulators Binders of Rho GTPases (Borgs). In addition, the brain-specific nucleotide exchange factor kalirin-7 (Kal7) was identified as an MK5 interaction partner and substrate protein. In transfected primary neurons, Sept7-dependent dendrite development and spine formation are stimulated by the ERK3/MK5 module. Thus, the regulation of neuronal morphogenesis is proposed as the first physiological function of the ERK3/MK5 signaling module.

The extracellular signal-regulated kinase 3 (mitogen-activated protein kinase 6 [MAPK6])-MAPK-activated protein kinase 5 signaling complex regulates septin function and dendrite morphology.

The development of the dentate gyrus is characterized by distinct phases establishing a durable stem-cell pool required for postnatal and adult neurogenesis. Here, we report that Bcl11b/Ctip2, a zinc finger transcription factor expressed in postmitotic neurons, plays a critical role during postnatal development of the dentate gyrus. Forebrain-specific ablation of Bcl11b uncovers dual phase-specific functions of Bcl11b demonstrated by feedback control of the progenitor cell compartment as well as regulation of granule cell differentiation, leading to impaired spatial learning and memory in mutants. Surprisingly, we identified Desmoplakin as a direct transcriptional target of Bcl11b. Similarly to Bcl11b, postnatal neurogenesis and granule cell differentiation are impaired in Desmoplakin mutants. Re-expression of Desmoplakin in Bcl11b mutants rescues impaired neurogenesis, suggesting Desmoplakin to be an essential downstream effector of Bcl11b in hippocampal development. Together, our data define an important novel regulatory pathway in hippocampal development, by linking transcriptional functions of Bcl11b to Desmoplakin, a molecule known to act on cell adhesion.

A dual function of Bcl11b/Ctip2 in hippocampal neurogenesis.

Interneurons in the dorsal spinal cord process and relay innocuous and nociceptive somatosensory information from cutaneous receptors that sense touch, temperature and pain. These neurons display a well-defined organization with respect to their afferent innervation. Nociceptive afferents innervate lamina I and II, while cutaneous mechanosensory afferents primarily innervate sensory interneurons that are located in lamina III-IV. In this study, we outline a combinatorial transcription factor code that defines nine different inhibitory and excitatory interneuron populations in laminae III-IV of the postnatal cord. This transcription factor code reveals a high degree of molecular diversity in the neurons that make up laminae III-IV, and it lays the foundation for systematically analyzing and manipulating these different neuronal populations to assess their function. In addition, we find that many of the transcription factors that are expressed in the dorsal spinal cord at early postnatal times continue to be expressed in the adult, raising questions about their function in mature neurons and opening the door to their genetic manipulation in adult animals.

A transcription factor code defines nine sensory interneuron subtypes in the mechanosensory area of the spinal cord.

During neocortical development, neurons undergo polarization, oriented migration, and layer-type-specific differentiation. The transcriptional programs underlying these processes are not completely understood. Here, we show that the transcription factor Bcl11a regulates polarity and migration of upper layer neurons. Bcl11a-deficient late-born neurons fail to correctly switch from multipolar to bipolar morphology, resulting in impaired radial migration. We show that the expression of Sema3c is increased in migrating Bcl11a-deficient neurons and that Bcl11a is a direct negative regulator of Sema3c transcription. In vivo gain-of-function and rescue experiments demonstrate that Sema3c is a major downstream effector of Bcl11a required for the cell polarity switch and for the migration of upper layer neurons. Our data uncover a novel Bcl11a/Sema3c-dependent regulatory pathway used by migrating cortical neurons.

Stefan Britsch

Institute of Molecular and Cellular Anatomy

University of Ulm

Ex Utero Electroporation and Organotypic Slice Culture of Mouse Hippocampal Tissue

Time-lapse Confocal Imaging of Migrating Neurons in Organotypic Slice Culture of Embryonic Mouse Brain Using In Utero Electroporation

Stefan Britsch

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Institute of Molecular and Cellular Anatomy

University of Ulm

Ex Utero Electroporation and Organotypic Slice Culture of Mouse Hippocampal Tissue

Time-lapse Confocal Imaging of Migrating Neurons in Organotypic Slice Culture of Embryonic Mouse Brain Using In Utero Electroporation

Institute of Molecular and Cellular Anatomy