Biomedical subjects

Andre M Goffinet

Publications and source records attributed to Andre M Goffinet.

6 recordsLinked to original sources

PubMed2005

Protocadherin Celsr3 is crucial in axonal tract development.

In the embryonic CNS, the development of axonal tracts is required for the formation of connections and is regulated by multiple genetic and microenvironmental factors. Here we show that mice with inactivation of Celsr3, an ortholog of Drosophila melanogaster flamingo (fmi; also known as starry night, stan) that encodes a seven-pass protocadherin, have marked, selective anomalies of several major axonal fascicles, implicating protocadherins in axonal development in the mammalian CNS for the first time. In flies, fmi controls planar cell polarity (PCP) in a frizzled-dependent but wingless-independent manner. The neural phenotype in Celsr3 mutant mice is similar to that caused by inactivation of Fzd3, a member of the frizzled family. Celsr3 and Fzd3 are expressed together during brain development and may act in synergy. Thus, a genetic pathway analogous to the one that controls PCP is key in the development of the axonal blueprint.

Animals↗

PubMed2004

Expression of the chemokine receptor Cxcr4 mRNA during mouse brain development.

The expression of Cxcr4 mRNA that encodes the receptor for the chemokine Sdf1 was studied during mouse brain development using in situ hybridization, from E9.5 to maturity at P21. At embryonic stages, expression is prominent in ventricular zones of stem cell proliferation. This abates during the postnatal period in parallel to the depopulation of ventricular zones. In addition, the Cxcr4 gene is expressed in some differentiating neuronal populations at E12.5, E14.5 and E17.5, such as scattered cells in the reticular formation, cranial nerve nuclei, peripheral ganglia, cerebellar external granule cells, zona incerta, ventral lateral geniculate thalamic nuclei, olfactory glomerular layer, hippocampal primordium and telencephalic preplate. High levels of expression are detected in preplate derivatives in all sectors of the marginal zone (MZ) of the telencephalic vesicles, including Cajal-Retzius (CR) cells, other MZ cells and subplate neurons. Cxcr4 expression is progressively downregulated postnatally, but remains significantly associated in the adult with Bergman glia in the cerebellum, the subgranular layer of the dentate gyrus, and the olfactory glomerular layer. In contrast, expression of Sdf1 mRNA is confined to the meninges and, in embryos, to the telencephalic intermediate zone. This expression pattern suggests that Sdf1 and its receptor Cxcr4 may exert trophic influences on precursor cell proliferation and some neuronal targets that remain to be identified and studied further.

Animals↗

PubMed2003

Disabled-1 mRNA and protein expression in developing human cortex.

Disabled-1 (Dab1) forms part of the Reelin-Dab1 signalling pathway that controls neuronal positioning during brain development; Dab1 deficiency gives rise to a reeler-like inversion of cortical layers. To establish a timetable of Dab1 expression in developing human brain, Dab1 mRNA and protein expression were studied in prenatal human cortex. The earliest Dab1 signal was detected at 7 gestational weeks (GW), the stage of transition from preplate to cortical plate, suggesting a role of the Reelin-Dab1 signalling pathway in preplate partition. From 12 to 20 GW, the period of maximum cortical migration, Dab1 expression was prominent in the upper tiers of the cortical plate, to decline after midgestation. Radially orientated apical dendrites of Dab1-expressing neurons indicated a predominant pyramidal phenotype. Pyramidal cells in hippocampus and entorhinal cortex displayed a more protracted time of Dab1 expression compared to neocortex. In addition, at later stages (18-25 GW), Dab1 was also expressed in large neurons scattered throughout intermediate zone and subplate. From 14 to 22 GW, particularly high levels of Dab1 mRNA and protein were observed in cells of the ventricular/subventricular zone displaying the morphology of radial glia. The partial colocalization of vimentin and Dab1 in cells of the ventricular zone supported a radial glia phenotype. The concentration of Dab1 protein in ventricular endfeet and initial portions of radial processes of ventricular-zone cells points to a possible involvement of Dab1 in neurogenesis. Furthermore, a subset of Cajal-Retzius cells in the marginal zone colocalized Dab1 and Reelin, and may thus represent a novel target of the Reelin-Dab1 signalling pathway.

Adaptor Proteins, Signal Transducing↗

PubMed2002

The gene encoding disabled-1 (DAB1), the intracellular adaptor of the Reelin pathway, reveals unusual complexity in human and mouse.

The Disabled-1 (Dab1) gene encodes a key regulator of Reelin signaling. Reelin is a large glycoprotein secreted by neurons of the developing brain, particularly Cajal-Retzius cells. The DAB1 protein docks to the intracellular part of the Reelin very low density lipoprotein receptor and apoE receptor type 2 and becomes tyrosine-phosphorylated following binding of Reelin to cortical neurons. In mice, mutations of Dab1 and Reelin generate identical phenotypes. In humans, Reelin mutations are associated with brain malformations and mental retardation; mutations in DAB1 have not been identified. Here, we define the organization of Dab1, which is similar in human and mouse. The Dab1 gene spreads over 1100 kb of genomic DNA and is composed of 14 exons encoding the major protein form, some alternative internal exons, and multiple 5'-exons. Alternative polyadenylation and splicing events generate DAB1 isoforms. Several 5'-untranslated regions (UTRs) correspond to different promoters. Two 5'-UTRs (1A and 1B) are predominantly used in the developing brain. 5'-UTR 1B is composed of 10 small exons spread over 800 kb. With a genomic length of 1.1 Mbp for a coding region of 5.5 kb, Dab1 provides a rare example of genomic complexity, which will impede the identification of human mutations.

Adaptor Proteins, Signal Transducing↗

PubMed2002

A reeler mutant mouse with a new, spontaneous mutation in the reelin gene.

In one of our mouse colonies a reeler-like phenotype appeared spontaneously. The brain histology was identical to the known reeler phenotype. Northern and Western blot analysis and a complementation test showed that the defect is located to the reelin gene. Southern blot and PCR analysis together with information obtained from sequence databases revealed that this defective reelin gene had an approximately 24-kb intragenic deletion comprising exons 13-20.

Animals↗

PubMed2002

A modification of Representational Difference Analysis, with application to the cloning of a candidate in the Reelin signalling pathway.

BACKGROUND: cDNA-RDA is one of the subtractive cloning techniques used to isolate differentially expressed genes between two complex cDNA populations. In the present study we present a modification of the protocol described by Hubank and Schatz. RESULTS: In the post-hybridization mix, the 5'-ends of homoduplexes of interest (tester-tester) are filled-in with alpha-thio-deoxynucleotides. Unprotected duplexes, as well as the single-stranded DNA fragments, are degraded using ExoIII and Mung Bean Nuclease, prior to PCR subtraction, resulting in less complex difference products. We illustrate this modification by the cloning of a new gene which is differentially expressed in normal, reelin and Dab1 mutant mice and is a candidate member of the Reelin signalling pathway involved in brain development. CONCLUSION: We propose a modification of cDNA-RDA that may reduce the complexity of the post-hybridization mix and thus facilitate the amplification of differentially expressed products.

Journal Article↗