Molecular Neurobiology

Research Interests

We are interested in understanding the mechanisms that govern gene expression during development, in particular in the embryonic vertebrate nervous system.

The assembly of a fully functional nervous system, with all its diversity and complexity, depends on the coordinate generation of both neurons and glia from differentiating multipotent neural stem cells in the developing embryo. The progression of this differentiation process is associated and controlled by changes in gene expression programs that need to be very tightly regulated. For the moment we are mostly interested in understanding how such regulation takes place at the transcription level, by focusing our studies on the role played by various transcription factors in neurogenesis. We aim at characterizing their transcriptional networks, as well as understanding the molecular mechanisms by which such programs are regulated, and how they contribute to the acquisition of specific cellular phenotypes. For that we take advantage of recently developed genomic approaches that allow the characterization of transcriptional programs at a genome wide level (eg. ChIP-on-chip or ChIP-seq). We use such techniques, complemented with more classical methods to study gene expression, having the mouse embryo as a model system. Although the studies we conduct are within so called basic research, understanding how tissue specific patterns of gene expression are established during development will be of great importance, should stem cell technology be used in clinical applications.

Informal enquiries on research or available positions in our group are welcome and should be sent to Diogo S. Castro

Group Members

Vera Teixeira	Postdoc
	Tel: 21 446 4687
Alexandre Raposo	Postdoc
	Tel: 21 446 4687
Pedro Rosmaninho	Trainee
	Tel: 21 440 7917
Francisca Vasconcelos	2009 PIBS
	Tel: 21 449 7900

Research Project

Characterization of a neurogenic program and its regulation by the vertebrate proneural factor Mash1

The coordinate regulation of many aspects of the neurogenic differentiation program is controlled, to large extent, by basic helix-loop-helix (bHLH) transcription factors encoded by so called proneural genes. Vertebrate proneural factors promote neuronal commitment of multipotent neural progenitors, contribute to the specification of neuronal subtype identities, drive neuronal progenitors out of the cell cycle, and promote neuronal migration and differentiation. In spite of the wealth of information on their cellular activities, the molecular mechanisms by which proneural proteins such as Mash1 regulate neurogenesis are poorly understood, with the identity of their target genes remaining largely unknown. Identifying Mash1 target genes, and studying how their coordinated regulation results in a coherent neurogenic program, is essential to understand how neural stem cells differentiate into neurons. Because embryonic neurogenesis is not a synchronized process, gene expression studies are difficult to perform in vivo, and complementary models are therefore required. We have recently developed a Mash1 inducible system that when applied to a neural stem cell model, results in the generation of Mash1 induced neuronal progenitors that differentiate into GABAergic neurons in a synchronized manner. We are using this system in order to characterize the neurogenic differentiation program induced by Mash1. In particular, we are interested in understanding the establishment of its temporal pattern, by investigating possible transcriptional and epigenetic mechanisms. For that we are using a combination of expression profiling with genome wide location analyses followed by massive parallel sequencing (ChIP-seq)

Funding

FCT, Portugal: PTDC/SAU-NEU/100208/2008
Characterization of a neurogenic program activated by the proneural factor Mash1

Collaborators

François Guillemot, National Institute for Medical research, London, UK
Noel Buckley, King’s College, London, UK

Research Project

Characterization of the transcriptional program regulated by Drg11 (Prrxl1) during differentiation of the nociceptive system

Drg11 (also called Prrxl1) is a paired-like homeodomain transcription factor involved in the development/maintenance of both spinal cord dorsal horn and peripheral nociceptor neurons, which specifically integrate the pain stimuli. The fact that DRG11 is expressed in both peripheral sensory neurons and their central synaptic targets suggests a role in the establishment of connectivity in the nociceptive system, an idea also supported by the analyses of the DRG11 null mice. These animals display several developmental defects, including abnormalities in the penetration of sensory afferent fibers into the spinal cord and in the differentiation of their target neurons. Further advancements on the understanding of the development of the nocyceptive system would greatly benefit from the characterization of the molecular mechanisms mediating DRG11 function. Together with researchers at the laboratory of Deolinda Lima at the University of Porto, who have been working extensively on the function of DRG11 in the developing nervous system, we are characterizing the transcriptional network downstream DRG11. Direct target genes of DRG11 are being identified by using a combination of expression profiling and genomic location analyses, using dissected tissue from both wild type and DRG11 null mice.

Collaborators

Filipe Almeida Monteiro and Deolinda Lima
Laboratory of Molecular and Cell Biology, Faculty of Medicine, University of Porto, Portugal

Research Project

Promoter occupancy studies of Mash1 in differentiating olygodendrocytes

Although the proneural protein Mash1 is more commonly recognized for its pivotal function in neurogenesis, a novel role of this transcription factor in the specification of oligodendrocyte precursor cells was recently uncovered. In order to better understand the cellular function of Mash1 in differentiating oligodendrocytes, we are using genome-wide location analyses (by ChIP-on-chip), aiming at characterizing Mash1 targets in this developing context. Together with researchers at the laboratory of Carlos Parras we are following an in vivo approach, using FACSorted populations of GFP-expressing oligodendrocyte progenitors from transgenic mouse models.

Collaborators

Hessameh Hassani and Carlos Parras, Inserm UMR-S 975/CNRS UMR 7225, Paris, France

Publications

(Selected) Updated May (2011).

Castro D S, Martynoga B, Parras C, Ramesh V, Pacary E, Johnston C, Drechsel D, Lebel-Potter M, Galinanes-Garcia L, Hunt C, Dolle D, Bithell A, Ettwiller L, Buckley N and Guillemot F (2011). A novel function of the proneural factor Ascl1 in progenitor proliferation identified by genome-wide characterization of its targets Genes & Dev 25 :930-945

Heng J I, Nguyen L, Castro D S, Zimer C, Wildner H, Armant O, Skowronska- Krawczyk D,Bedogni F, Matter J M, Hevner R and Guillemot, F. (2008). Neurogenin 2 controls cortical neuron migration through regulation of Rnd2. Nature 455(7209) :114-8

Castro D S, Skowronska-Krawczyk D, Armant O, Donaldson I J, Parras C, Hunt C, Critchley J, Nguyen L, Gossler A, Gottgens B, Matter JM and Guillemot F. (2006). Proneural bHLH and Brn proteins coregulate a neurogenic program through cooperative binding to a conserved DNA motif Dev Cell 11 :831-844

Bertrand N. (*), Castro, D.S.(*), and Guillemot, F. (2002). Proneural genes and the specification of neural cell types. Nat Rev Neurosci 3(7) :517-30