A8 - Wittbrodt

In the previous funding periods we have mainly focused in the early patterning steps leading to the establishment of the eye field, as well as the morphogenetic events resulting in the formation of a curved-layered retina containing postmitotic neurons [1-4]. In the coming funding period we will move move on in time to characterize two other subsequent processes: a) how the different types of retinal neurons communicate to each other and b) the molecular mechanisms underlying the generation and integration of new neurons that sustains the continuous growth of the eye.

In the coming funding period we will address two complementary questions:
On the one hand we will investigate the proliferation/differentiation in development and regeneration in different experimental and mutant (bean-shaped eye) conditions in order to gain insight into the genetics of retinal growth control.

In order to follow cells on their path from a progenitor cell to a fully differentiated neuron or glia cell, we will establish and combine permanent and non-invasive cell labelling techniques(1), techniques to kill particular neurons in a reproducible way (2), latest imaging technologies (3) and forward genetics (4) employing mutants (identified in the lab) in which the proliferation/differentiation rate of the CMZ is affected. Of particular interest is the bean-shaped eye (bns) mutant, in which the CMZ retains stem cell properties while differentiation is dramatically decreased. These features make the mutant ideally suited to study the molecular requirements for secondary retinal neurogenesis.

In parallel we will build on our expertise in imaging and functional characterisation of mutants affecting apico-basal polarity to extend our scope and analyze early synaptogenesis in wild type and mutant medaka retinae. Towards that aim we will employ in vivo imaging to visualize and understand how synapses form in retinal development, growth (and regeneration). We will focus on the synaptogenesis between cells of the ONL and their respective targets (photoreceptor-bipolar cells, bipolar-retinal ganglion cells). The role of cell polarity in synaptogenesis will be addressed investigating the processes in two mutants (medeka, 140-3-3/mosaic eyes) that we had characterized in the previous funding period. Both show pronounced apico-basal polarity defects. Subtypes of retinal cells will be labeled at the single cell level using specific drivers.  This will allow clonal analysis, to functionally dissect the highly complex network of the retina.

To complement the several transgenic lines labelling specific retinal cell types available for both sub-projects, complementary lines specifically expressing functional markers will be generated using the meganuclease approach [5].

The ultimate aim is to combine the findings of the parallel approaches on retinal growth control and synaptogenesis to gain insights on how a functional neuronal network forms and regenerates.

Aufbauend auf den Ergebnissen der vorangegangenen Förderperioden planen wir im vorliegenden Antrag die Untersuchung der kontinuierlichen retinalen Differenzierung im peripheren Bereich der Fisch Retina und der damit einhergehenden kontinuierlichen funktionalen Verschaltung, der Synaptogenese. In beiden Projekten bauen wir auf Mutanten in Medaka, die die jeweiligen Aspekte beeinflussen und erwarten uns wichtige Erkenntnisse zum Verständnis der Koordination von Proliferation, Differenzierung und Synaptogenese in einem experimentell gut zu manipulierenden Vertebratensystem.

Own project-related publications since the last application (2005)

Martinez-Morales, J.-R., Henrich, T., Ramialison, M., and Wittbrodt, J.(2007) New Genes in the Evolution of the Neural Crest Differentiation Program. Genome Biol 8: R36

Rembold, M., Loosli, F., Adams, R. J., and Wittbrodt, J.(2006) Individual cell migration serves as the driving force for optic vesicle evagination. Science 313: 1130-1134

Martinez-Morales, J.-R., Del Bene, F., Nica, G., Hammerschmidt, M., Bovolenta, P., and Wittbrodt, J.(2005) Differentiation of the Vertebrate Retina Is Coordinated by an FGF Signaling Center. Developmental Cell 8: 565-574

Own project-related publications (submitted / in preparation)

Martinez-Morales, J.-R., Simpson, J. C., Greger, K., Rembold, M., Quiring, R., Himmelbauer, H., Pepperkok, R., and Wittbrodt, J.(2008) Ojoplano links polarized secretion to tissue morphogenesis. under revision

Loosli, F., Swiercz, J., Müller, C., Offermanns, S., and Wittbrodt, J.(2008) A novel rho-GEF affected in the medaka mutant medeka couples cell polarity, proliferation and migration. in preparation

Own project-related publications prior to 2005

Poggi, L., Vottari, T., Barsacchi, G., Wittbrodt, J., and Vignali, R. (2004) The homeobox gene Xbh1 cooperates with proneural genes to specify ganglion cell fate in the Xenopus neural retina. Development 1331: 2305-2315

Martinez-Morales, J.-R., Naruse, K., Mitani, H., Shima, A., and Wittbrodt, J.(2004) Rapid chromosomal assignment of Medaka mutants by bulked segregant analysis. Gene 329: 159-165

Loosli, F., Del Bene, F., Quiring, R., Rembold, M., Martinez-Morales, J.-R., Carl, M., Grabher, C., Iquel, C., Krone, A., Wittbrodt, B., Winkler, S., Sasado, T., Morinaga, C., Suwa, H., Niwa, K., Henrich, T., Deguchi, T., Hirose, Y., Iwanami, N., Kunimatsu, S., Osakada, M., Watanabe, T., Yasuoka, A., Yoda, H., Winkler, C., Elmasri, H., Kondoh, H., Furutani-Seiki, M., and Wittbrodt, J.(2004) Mutations affecting retina development in Medaka. Mech Dev 121: 703-714

Furutani-Seiki, M., and Wittbrodt, J.(2004) Medaka and zebrafish, an evolutionary twin study. MOD 121: 629-637

Furutani-Seiki, M., Sasado, T., Morinaga, C., Suwa, H., Niwa, K., Yoda, H., Deguchi, T., Hirose, Y., Yasuoka, A., Henrich, T., Watanabe, T., Iwanami, N., Kitagawa, D., Saito, K., Asaka, S., Osakada, M., Kunimatsu, S., Momoi, A., Elmasri, H., Winkler, C., Ramialison, M., Loosli, F., Quiring, R., Carl, M., Grabher, C., Winkler, S., Del Bene, F., Shinomiya, A., Kota, Y., Yamanaka, T., Okamoto, Y., Takahashi, K., Todo, T., Abe, K., Takahama, Y., Tanaka, M., Mitani, H., Katada, T., Nishina, H., Nakajima, N., Wittbrodt, J., and Kondoh, H. (2004) A systematic genome-wide screen for mutations affecting organogenesis in Medaka, Oryzias latipes. MOD 121: 647-658

Del Bene, F., Tessmar-Raible, K., and Wittbrodt, J.(2004) Direct interaction of geminin and Six3 in eye development. Nature 427: 745-749

Lopez-Rios, J., Tessmar, K., Loosli, F., Wittbrodt, J., and Bovolenta, P. (2003) Six3 and Six6 activity is modulated by members of the groucho family. Development 130: 185-195

Loosli, F., Staub, W., Finger-Baier, K., Ober, E., Verkade, H., Wittbrodt, J., and Baier, H. (2003) Loss of eyes in zebrafish caused by mutation of chokh/rx3. EMBO Reports 4: 894-899

Carl, M., Loosli, F., and Wittbrodt, J.(2002) Six3 inactivation reveals its essential role for the formation and patterning of the vertebrate eye. Development 129: 4057-4063

Selected publications from other projects outside the SFB since 2005

Haudry, Y., Berube, H., Letunic, I., Weeber, P. D., Gagneur, J., Girardot, C., Kapushesky, M., Arendt, D., Bork, P., Brazma, A., Furlong, E. E., Wittbrodt, J., and Henrich, T. (2008) 4DXpress: a database for cross-species expression pattern comparisons. Nucleic Acids Res 36: D847-853

Grabher, C., Cliffe, A., Miura, K., Hayflick, J., Pepperkok, R., Rørth, P., and Wittbrodt, J.(2007) Birth and life of tissue macrophages and their migration in embryogenesis and inflammation in medaka. Journal of Leukocyte Biology 81: 263-271

Ettwiller, L., Paten, B., Ramialison, M., Birney, E., and Wittbrodt, J.(2007) TRAWLER: de novo Regulatory Motif Discovery Pipeline for Chromatin Immunoprecipitation. Nature Methods: 563-565

Del Bene, F., Ettwiller, L., Skowronska-Krawczyk, D., Baier, H., Matter, J. M., Birney, E., and Wittbrodt, J.(2007) In vivo validation of a computationally predicted conserved Ath5 target gene set. PLoS Genet 3: 1661-1671

Wichmann, O., Wittbrodt, J., and Schultz, C. (2006) A small-molecule FRET probe to monitor phospholipase A2 activity in cells and organisms. Angew Chem Int Ed Engl 45: 508-512

Rembold, M., Lahiri, K., Foulkes, N. S., and Wittbrodt, J.(2006) Transgenesis in fish: efficient selection of transgenic fish by co-injection with a fluorescent reporter construct. Nature Protocols 1: 1133 - 1139

Henrich, T., Ramialison, M., Wittbrodt, B., Assouline, B., Bourrat, F., Berger, A., Himmelbauer, H., Sasaki, T., Shimizu, N., Westerfield, M., Kondoh, H., and Wittbrodt, J. (2005) MEPD: a resource for medaka gene expression patterns. Bioinformatics 21: 3195-3197

Ettwiller, L., Paten, B., Souren, M., Loosli, F., Wittbrodt, J., and Birney, E. (2005) The discovery, positioning and verification of a set of transcription-associated motifs in vertebrates. Genome Biol 6: R104

Jochen Wittbrodt

Abteilung für Molekulare Entwicklungsbiologie/ Tierphysiologie

Institut für Zoologie

Im Neuenheimer Feld 230

69115 Heidelberg

Phone:    06221-546499
email:     Jochen.wittbrodt@zoo.uni-heidelberg