Principal investigator: Cristina Pujades

Team:

Simone Calzolari (PhD student)

Sylvia Dyballa (PhD student)

Javier Terriente (postdoctoral fellow)

Former members:

Ferran Aragon (PhD student 2004-08)
Citlali Vázquez-Echeverría (PhD student 2004-2008)
Eva Jimenez-Guri (postdoctoral fellow 2008-10)
Dora Sapède (postdoctoral fellow 2007-2010)

The long-term goal of our group is to understand the molecular and cellular mechanisms governing the patterning along the anterior-posterior (AP) axis of the hindbrain, the posterior part of the brain. AP patterning of the hindbrain involves a segmentation process, which leads to the formation of morphological bulges called rhombomeres. This segmentation process sets up the stereotyped pattern of neuronal specification in the brainstem. Our interest is focused on what mechanisms underlie rhombomere boundary formation, and what are the early events that dictate the overall segmentation of the hindbrain. Another aspect of our work concerns the study of the role of the hindbrain signals in instructing the development of adjacent structures such as the otic primordium.

Our main funding sources are: Ministerio de Ciencia e Innovacion (Spain), Programme International de Cooperation Scientifique (PICS, Generalitat de Catalunya-CNRS), and AGAUR (Generalitat de Catalunya). 

PROJECTS

1. Establishment of rhombomeric boundaries.

During neurulation in vertebrates, the hindbrain is transiently subdivided along its AP axis into a series of segments termed rhombomeres, which are compartments of cell lineage restriction. The mechanisms involved in the activation of segmentally expressed genes remain to be understood. We are working with several approaches to tackle this issue.

1.1. Study of the mechanisms responsible of the positioning of the r4/r5. We want to understand whether the establishment of r4/r5 follows a genetic program that has been evolutionary conserved. The prospective r4/r5 boundary forms at the interface between the expression territories of two homeobox genes, iro7 rostrally and vHnf1 caudally, and it is positioned by mutual repression between these two transcription factors (Lecaudey et al., 2004; Sapède and Pujades, unpublished results). We are currently doing and exhaustive analysis of the regulatory regions driving expression of Irx and vhnf1 genes to anterior and posterior hindbrain territories in different vertebrate species such as lamprey, zebrafish, mice and chick.

1.2. How interhombomeric boundaries are settled down? Genes expressed in restricted rhombomeric domains initially show diffuse boundaries and these boundaries progressively sharpen to form straight interfaces. Our interest is to unveil the molecular mechanisms involved in setting the rhombomeric boundaries. For this purpose we take 2 different approaches: i) to do a rhombomeric cell tracing analysis in mice and in zebrafish; ii) to identify novel genes differentially expressed in a rhombomere-restricted pattern.

2. Hindbrain signals instructing otic development.

The hindbrain and the otic placode keep an invariant spatial relation in many animal species. The caudal hindbrain also sends instructive cues essential for the development of the inner ear. Our group has contributed to demonstrate the importance of hindbrain-derived signals in patterning the otic primordium, and therefore in the establishment of the otic neurosensory domains in zebrafish and mice (Lecaudey et al., 2007; Vazquez-Echeverria et al., 2008).

Our main aims are: i) to dissect the hierarchy of signals from the hindbrain that provide positional information cues to different otic territories as well as the identification of the otic targets of those signals; ii) the study of the wiring of the otic vesicle with the relay centres of the hindbrain. We are mainly interested in how the sensory acoustic information is topographically represented at central levels.                                         

RELATED PUBLICATIONS

Jimenez-Guri, E, and Pujades, C. An ancient mechanism of hindbrain patterning has been conserved in vertebrate evolution. Evolution and Development, 2011

Jimenez-Guri, E, Udina, F, Colas, JF, Sharpe, J,  Padrón, L, Torres M, Pujades, C. Clonal analysis in mice underlines the importance of positional information during hindbrain segmentation. PLoS ONE 5(4): e10112. doi:10.1371/journal.pone.0010112, 2010

Sapède, D. and Pujades, C. Hedgehog signalling governs the development of sensory epithelium and its associated innervation in the zebrafish inner ear. J. Neurosc. 30: 3612-3623, 2010

Aragón, F. and Pujades, C. FGF signaling controls caudal hindbrain specification through Ras-ERK1/2 pathway, BMC Dev. Biol. 9:61, 2009

Alsina, B., Giraldez, F. and Pujades, C. Patterning and cell fate in inner ear development. Review in Science in Hispania Special Issue, Int. J. Dev. Biol. 53(8-10):1503-13, 2009

Vázquez-Echeverría, C., Dominguez-Frutos, E., Charnay, P., Schimmang, T. and Pujades, C. Analysis of kreisler mutants reveals new roles of the hindbrain-derived signals in the establishment of the otic neurogenic domain. Dev. Biol., 322(1):167-782, 2008

Schneider-Maunoury, S. and Pujades, C. Hindbrain signals in otic regionalization: walk on the wild side. Review in Ear Development Special Issue, Ed. F. Giraldez and B. Fritzch Int. J. Dev. Biol 51(6-7):495-506, 2007

Lecaudey, V., Ulloa, E., Anselme, I., Schneider-Maunoury, S., Pujades, C. Hypomorphic vhnf1 mutation leads to mispatterning of the otic vesicle. Dev. Biol. 303, 134-143, 2007

Pujades, C., Kamaid, A., Alsina, B., Giraldez, F. BMP4 regulates the development of hair-cells by modulating progenitor cell survival. Dev. Biol., Apr 1;292(1):55-67, 2006

Aragón, F., Vazquez-Echeverría, C., Ulloa, E., Reber, M., Cereghini, S., Alsina, B., Giraldez, F., Pujades, C. vHnf1 regulates specification of caudal rhombomere identity in the chick hindbrain. Dev. Dyn. 234(3), pp. 567-76, 2005

B. Alsina, G. Abello, E. Ulloa, D. Henrique, C. Pujades, F. Giraldez. FGF10 is required for epithelial differentiation of otic neuroblasts. Dev. Biol. 267:119-134, 2004

F. Mechta, F. Giudicelli, C. Pujades, P. Charnay, M. Yaniv. kreisler control c-jun regulation and function in the developing hindbrain. Dev. Biol. 258,: 419-431, 2003

O. Voiculescu, E. Taillebourg, C. Pujades, C. Kress, S. Buart, P. Charnay, S. Scheneider-Maunoury. Hindbrain patterning : Krox20 couples segmentation and specification of regional identity. Development 128: 4967-4978, 2001

F. Helmbacher, C. Pujades, C. Desmarquet, M. Frain, F. Rijli, P. Chambon, P. Charnay. Hoxa-1 and Krox-20 synergize in the patterning of rhombomere 3. Development 125: 4739-4748, 1998