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Rodrigo Young

Post Doc
020 3549 5514 (t)

I did my PhD in Miguel Allende’s lab at the University of Chile. My original project was to screen for pineal organ mutants from a collection of retroviral mutagenised zebrafish in Nancy Hopkins lab at MIT. In the process of screening, I became interested in the zebrafish tcf4 gene, which finally became the main focus of my thesis. I was then, and still am, intrigued by the quantity of splice variants that this gene can express. This, plus the fact that Tcf4 is a transcriptional effector of the Wnt/ßcatenin pathway, makes it relevant to many cell and developmental biology, stem cell and disease processes. We speculated that the different splice variants might have different activities in different Wnt-dependent developmental processes. My data suggests that this is indeed the case and we aim to publish this work soon.

While working in Miguel and Nancy’s lab, I became aware of the power of mutagenising genes in fish to study particular biological functions. It is very easy to randomly mutagenise the zebrafish genome and then screen for mutants that affect specific embryo/cell biology functions; the main requirements are lots of fish tanks and lots of manpower. Nevertheless, for many genes, abrogation of function has no effect on viability, and embryos can develop to adulthood as viable and fertile fish. This is not only observed in zebrafish but also in mice, worms and yeast. For instance, around 70% of the genes in C. elegans show no overt phenotype when mutated.

An example of this is the headless/tcf3a mutant, which as a zygotic mutant has no phenotype and is viable. In contrast, the lack of maternal (mRNA/protein added by the mother in the egg) and zygotic components of the gene leads to eyeless embryos. In fly, worms and yeast, mutants with mild or no phenotype have been used to carry out enhancer mutagenesis screens to assess genetic interactions. Two genes are considered to interact genetically if the phenotype of a specific structure or process is only seen, or is enhanced, when both genes are mutated, but not as single mutations. Such genetic interactions relate the function of the “interacting” genes to the same process.

Based on this principle, I decided to carry out an enhancer mutagenesis screen over a hdl/tcf3a background looking for recessive mutations that lead to an eyeless embryo phenotype. We conducted a pilot screen of about 100 F2 families and have found about 10 eyeless enhancers (Fig 1) of hdl plus other unexpected enhanced phenotypes. We are currently in the process of mapping our first enhancer mutant. Colleagues both from our lab and from other labs participated in this pilot screen and you can read more about this project on our Genetic Screens research web pages.

Given the success of the pilot screen, we have applied to the Wellcome Trust for funds to continue the screen and clone and characterise the novel mutations.

Fig.1. Eyeless phenotype enhancer mutations. A) wildtype. B) tcf3a+/-;enha36/a36 double mutant C) tcf3a+/-;enhg11/g11 double mutant.


Hüsken U, Stickney HL, Gestri G, Bianco IH, Faro A, Young RM, Roussigne M, Hawkins TA, Beretta CA, Brinkmann I, Paolini A, Jacinto R, Albadri S, Dreosti E, Tsalavouta M, Schwarz Q, Cavodeassi F, Barth AK, Wen L, Zhang B, Blader P, Yaksi E, Poggi L, Zigman M, Lin S, Wilson SW, Carl M. (2014)
Tcf7l2 is required for left-right asymmetric differentiation of habenular neurons.
Curr Biol. 2014 Oct 6;24(19):2217-27. doi: 10.1016/j.cub.2014.08.006.
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Moro E, Ozhan-Kizil G, Mongera A, Beis D, Wierzbicki C, Young RM, Bournele D, Domenichini A, Valdivia LE, Lum L, Chen C, Amatruda JF, Tiso N, Weidinger G, Argenton F. (2012)
In vivo Wnt signaling tracing through a transgenic biosensor fish reveals novel activity domains.
Dev Biol, 366 (2), 327-340
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Valdivia LE, Young RM, Hawkins TA, Stickney HL, Cavodeassi F, Schwarz Q, Pullin LM, Villegas R, Moro E, Argenton F, Allende ML, Wilson SW. (2011)
Lef1-dependent Wnt/{beta}-catenin signalling drives the proliferative engine that maintains tissue homeostasis during lateral line development.
Development. 2011 Sep;138(18):3931-41
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Cynthia L Andoniadou, Massimo Signore, Rodrigo M. Young, Carles Gaston-Massuet, Elaine Fuchs, Stephen W. Wilson, and Juan Pedro Martinez-Barbera (2011)
HESX1 and TCF3 mediated repression of Wntß-catenin targets is required for normal development of the anterior forebrain.
Development, In press

Ewan K, Pajak B, Stubbs M, Todd H, Barbeau O, Quevedo C, Botfield H, Young RM, Ruddle R, Samuel L, Battersby A, Raynaud F, Allen N, Wilson S, Latinkic B, Workman P, McDonald E, Blagg J, Aherne W, Dale T. (2010)
A useful approach to identify novel small-molecule inhibitors of Wnt-dependent transcription.
Cancer Res. 2010 Jul 15;70(14):5963-73
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Cavodeassi, F.; Kapsimali, M.; Wilson, S.W.; Young, R. (2009 )
Forebrain: early development
In L. R. Squire (editor) Encyclopedia of Neuroscience 4:321-325. Elsevier. Oxford:Academic Press.
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Cavodeassi, F., Carreira-Barbosa, F., Young, R.M., Concha, M.L., Allende, M.L., Houart, C., Tada, M., Wilson, S.W. (2005)
Early Stages of Zebrafish Eye Formation Require the Coordinated Activity of Wnt11, Fz5, and the Wnt/ -Catenin Pathway.
Neuron 47:43-56
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Young, R.M., Marty, S., Nakano, Y., Wang, H., Yamamoto, D., Lin, S., Allende, M.L. (2002)
Zebrafish yolk-specific not really started (nrs) gene is a vertebrate homolog of the Drosophila spinster gene and is essential for embryogenesis.
Dev. Dyn. 223: 298-305
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Young, R.M., Reyes, A., Allende, M.L. (2002)
Expression and splice variant analysis of the zebrafish tcf-4 transcription factor.
Mech. Dev. 117: 269-273
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