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Pavlos Alifragis

Publications and source records attributed to Pavlos Alifragis.

5 recordsLinked to original sources
PubMed2003

Restricted expression of Slap-1 in the rodent cerebral cortex.

The deep layers of the mammalian cerebral cortex contain pyramidal neurons that project predominantly to subcortical targets. To understand the mechanisms that determine the identity of deeper layer neurons, a PCR based subtractive hybridisation was performed to isolate genes that are specifically expressed during the specification of these neurons. One of the genes we isolated was the rat homologue of the mouse Slap-1. SLAP-1 is an adaptor protein containing SH2-SH3 domains and it participates in the signalling of Receptor Tyrosine Kinases. In situ hybridisation studies have shown that Slap-1 is not substantially expressed before E17. At later stages, it is specifically and selectively expressed by deeper layer neurons and by neurons of layers II/III in the developing cortex. The specific timing and location of its expression, suggests that this gene may play a role in the differentiation of these neurons.

Adaptor Proteins, Signal Transducing↗
PubMed2003

Two modes of recruitment of E(spl) repressors onto target genes.

The decision of ectodermal cells to adopt the sensory organ precursor fate in Drosophila is controlled by two classes of basic-helix-loop-helix transcription factors: the proneural Ac and Sc activators promote neural fate, whereas the E(spl) repressors suppress it. We show here that E(spl) proteins m7 and mgamma are potent inhibitors of neural fate, even in the presence of excess Sc activity and even when their DNA-binding basic domain has been inactivated. Furthermore, these E(spl) proteins can efficiently repress target genes that lack cognate DNA binding sites, as long as these genes are bound by Ac/Sc activators. This activity of E(spl)m7 and mgamma correlates with their ability to interact with proneural activators, through which they are probably tethered on target enhancers. Analysis of reporter genes and sensory organ (bristle) patterns reveals that, in addition to this indirect recruitment of E(spl) onto enhancers via protein-protein interaction with bound Ac/Sc factors, direct DNA binding of target genes by E(spl) also takes place. Irrespective of whether E(spl) are recruited via direct DNA binding or interaction with proneural proteins, the co-repressor Groucho is always needed for target gene repression.

Animals↗
PubMed2002

A novel method of labeling and characterizing migrating neurons in the developing central nervous system.

Neuronal migration, a discrete event in the developing nervous system, is currently being intensively investigated using a variety of anatomical and molecular approaches. Using 4-chloromethyl benzoyl amino tetramethyl rhodamine (CMTMR) coated particles, we describe here a novel and efficient method of tracer labeling to investigate cell migration in embryonic and postnatal brain. Further, we demonstrate that application of CMTMR facilitates the labeling of a large number of migrating cells and enables the characterization of their phenotypes with immunohistochemical and in situ hybridization techniques. We also illustrate that CMTMR labeling is ideally suited for time-lapse imaging of the behavior and dynamics of migrating cells.

Animals↗
PubMed2002

Ventricle-directed migration in the developing cerebral cortex.

It is believed that postmitotic neurons migrate away from their sites of origin in the germinal zones to populate distant targets. Contrary to this notion, we found, using time-lapse imaging of brain slices, populations of neurons positioned at various levels of the developing neocortex that migrate towards the cortical ventricular zone. After a pause in this proliferative zone, they migrate radially in the direction of the pial surface to take up positions in the cortical plate. Immunohistochemical analysis together with tracer labeling in brain slices showed that cells showing ventricle-directed migration in the developing cortex are GABAergic interneurons originating in the ganglionic eminence in the ventral telencephalon. We speculate that combinations of chemoattractant and chemorepellent molecules are involved in this ventricle-directed migration and that interneurons may seek the cortical ventricular zone to receive layer information.

Animals↗