Expression of the EMILIN-1 gene during mouse development.

Expression of EMILIN-1, the first member of a newly discovered family of extracellular matrix genes, has been investigated during mouse development. EMILIN-1 mRNA is detectable in morula and blastocyst by RT-PCR. First expression of the gene is found by in situ hybridization in ectoplacental cone in embryos of 6.5 days and in extraembryonic visceral endoderm at 7.5 days. The allantois is also labeled. Staining of ectoplacental cone-derived secondary trophoblast giant cells and spongiotrophoblast is strong up to 11.5 days and then declines. In the embryo, high levels of mRNA are initially expressed in blood vessels, perineural mesenchyme and somites at 8.5 days. Later on, intense labeling is identified in the mesenchymal component of organs anlage (i.e. lung and liver) and different mesenchymal condensations (i.e. limb bud and branchial arches). At late gestation staining is widely distributed in interstitial connective tissue and smooth muscle cell-rich tissues. The data suggest that EMILIN-1 may have a function in placenta formation and initial organogenesis and a later role in interstitial connective tissue.     

Expression of ric-8 (synembryn) gene in the nervous system of developing and adult mouse

Recent biochemical studies revealed that ric-8A encodes a guanine nucleotide exchange factor for a subset of Galpha proteins. Ric-8 is a key component of a signaling network in C. elegans that regulates neurotransmitter secretion and also plays a role in centrosome-mediated events during early embryogenesis. Here we show that during the early development in mice (E9.5-E12.0) ric-8 (synembryn) is expressed in the developing nervous system such as the cranial ganglia, neural tube, sympathetic chain and dorsal root ganglia. Ric-8 is also found in the lens, vomeronasal organ, and endolymphatic sac. In adult brain, it is expressed in the neocortex, hippocampus, and cerebellum as well as in the pineal gland and ependymal layer.     

Expression of the Prader-Willi gene Necdin during mouse nervous system development correlates with neuronal differentiation and p75NTR expression

The expression pattern of Necdin, a gene involved in the etiology of Prader-Willi syndrome and a member of the MAGE family of genes, is described during mouse nervous system development. Using RNA in situ hybridization, immunohistochemical staining, and colocalization with neuronal differentiation markers, we found that Necdin RNA and protein are expressed within post-mitotic neurons at all stages studied. From E10 to E12, Necdin is detected in all developing neurons, in both central and peripheral nervous system, with the highest expression levels in the diencephalon and the hindbrain. After E13, Necdin is expressed in specific structures of the nervous system, in particular the hypothalamus, the thalamus, and the pons, suggesting a specific developmental role therein. In addition, Necdin expression is also detected in non-neural tissues, such as the somites, the developing limb buds, the first branchial arches, the tong, and the axial muscles. Recently, Necdin and other MAGE proteins were found to interact in vitro with the intracellular domain of the p75NTR neurotrophin receptor, but this interaction has not been validated in vivo. We report here that the spatial and temporal expression of p75NTR is included in Necdin expression domain. These results are in agreement with Necdin proposed role on cell cycle arrest, inhibition of apoptosis and facilitation of neuronal differentiation in vitro, and with hypothalamic cellular deficiencies reported in mice with abrogation of the Necdin gene. Furthermore, they are also consistent with the putative role of Necdin in signaling events promoted by p75NTR during mouse nervous system development.     

Expression of glycoconjugates during development of the vertebrate nervous system

There is increasing evidence that carbohydrate antigens act as cell recognition molecules in the highly organized structure of the nervous system. These carbohydrate antigens may be expressed as glycolipids, glycoproteins or proteoglycans, and in some cases all three forms of these glycoconjugates, expressing identical carbohydrate epitopes, can be detected in a specific brain region. This article summarizes recent studies concerning the expression of glycoconjugates during development of the vertebrate central nervous system. These findings are discussed in association with current models of glycoconjugate function.     

c-fos proto-oncogene expression in the nervous system during mouse development.

I show, by in situ hybridization, that c-fos is expressed in the nervous system during mouse development. This expression was found to be restricted to specific regions at late stages of development (day 16 postcoitum), particularly to the spinal cord, dorsal root ganglia, and olfactory lobe. The c-fos protein may play a role in the maturation of these structures by activating specific genes.     

erg gene(s) expression during development of the nervous and muscular system of quail embryos

The expression pattern of K(+) currents is the principal regulator of electrical activity during development of the nervous and muscular system. We report here a study showing the expression pattern of HERG K(+) currents-encoding (erg) genes in various nervous and muscular tissues at different stages of quail embryo development.     

nanos1: a mouse nanos gene expressed in the central nervous system is dispensable for normal development

A mouse nanos (nanos1) gene was cloned and its function was examined by generating a gene-knockout mouse. The nanos1 gene encodes an RNA-binding protein, which contains a putative zinc-finger motif that exhibits similarity with other nanos-class genes in vertebrates and invertebrates. Although nanos1 is not detected in primordial germ cells, it is observed in seminiferous tubules of mature testis. Interestingly, maternally expressed nanos1 is observed in substantial amounts in oocytes, but the amount of maternal RNA is rapidly reduced after fertilization, and the transient zygotic nanos1 expression is observed in eight-cell embryos. At 12.5 days postcoitum, nanos1 is re-expressed in the central nervous system and the expression continues in the adult brain, in which the hippocampal formation is the predominant region. The nanos1 -deficient mice develop to term without any detectable abnormality and they are fertile. No significant neural defect is observed in terms of their behavior to date.     

Expression pattern of Wnt inhibitor factor 1(Wif1) during the development in mouse CNS

Wnt inhibitor factor-1 (WIF-1) is an extracellular antagonist of Wnts secreted proteins. Here we describe the expression pattern of Wif1 throughout the development of the mouse central nervous system (CNS). Wif1 mRNA can be detected as early as the developmental stage E11, and expression persists to adulthood. In embryonic stages, the level of Wif1 expression was very prominent in several areas including the cerebral cortex, the diencephalon and the midbrain, with the strongest level in the hippocampal plate and the diencephalon. However, after birth, the expression level of Wif1 decreased in the cortex and diencephalon. By adulthood, Wif1 is mainly expressed in the medial habenular nucleus (MHb) in the epithalamus, the mitral layer cells in the olfactory bulb and a few nuclei in the hypothalamus. Our data shows that the expression of Wif1 was very strong during embryonic development of the CNS and suggests that Wif1 may play an essential role in the spatial and temporal regulation of Wnt signals.     

Expression of vasorin (Vasn) during embryonic development of the mouse

The murine vasorin (Vasn) gene, initially known as Slit-like 2, encodes a transmembrane protein that shares structural similarities with the eponymous Slit proteins. However, whether it also shares functional similarities with these large secreted proteins remains to be elucidated. Here, we report expression of Vasn during embryonic and fetal development of the mouse using whole-mount in situ hybridization (WISH) and histochemical detection of β-galactosidase expressed from a targeted Vasn(lacZ) knock-in allele. Comparison of whole-mount staining patterns of both approaches showed identical expression domains, confirming that Vasn promoter-driven β-galactosidase expression faithfully reflects endogenous Vasn expression. Vasn is highly expressed in vascular smooth muscle cells (hence the name), a finding consistent with a previous report on its human homolog VASN, whose extracellular domain was shown to function as a TGF-β trap (Ikeda et al., 2004). Most striking, however, is Vasn's prominent expression in the developing skeletal system, starting as early as the first mesenchymal condensations appear. Moreover, distinct expression domains outside the bones, e.g., in the developing kidneys and lungs, suggest further roles for this gene in the mouse. Recently, it was shown that mitochondria-localized Vasn protects cells from TNFα- and hypoxia-induced apoptosis, and partial deletion of the Vasn coding sequence leads to increased sensitivity of hepatocytes to TNFα-induced apoptosis (Choksi et al., 2011). By providing a first comprehensive analysis of the Vasn expression pattern during mouse embryonic development, our study will help to further elucidate its biological functions.     

Expression of the T-box gene Eomesodermin during early mouse development.

We report the expression pattern of a murine homolog of the Xenopus laevis T-box gene Eomesodermin. mEomes expression is first detected in the extra-embryonic ectoderm prior to gastrulation, and persists there until head-fold stages. In the embryo proper, mEomes is expressed throughout the early primitive streak, nascent mesoderm and in the anterior visceral endoderm. Although mEomes expression disappears from the embryo at late-streak stages, a second domain of mEomes expression is observed in the telencephalon beginning around E10.5.     

Expression specificity of the mouse exonuclease 1 (mExo1) gene.

Genetic recombination involves either the homo-logous exchange of nearly identical chromosome regions or the direct alignment, annealing and ligation of processed DNA ends. These mechanisms are involved in repairing potentially lethal or mutagenic DNA damage and generating genetic diversity within the meiotic cell population and antibody repertoire. We report here the identification of a mouse gene, termed mExo1 for mouse exonuclease 1, which encodes a approximately 92 kDa protein that shares homology to proteins of the RAD2 nuclease family, most notably human 5' to 3' exonuclease Hex1/hExo1, yeast exonuclease 1 (Exo1) proteins and Drosophila melanogaster Tosca. The mExo1 gene maps to distal chromosome 1, consistent with the recent mapping of the orthologous HEX1 / hEXO1 gene to chromosome 1q42-q43. mExo1 is expressed prominently in testis, an area of active homologous recombination, and spleen, a prominent lymphoid tissue. An increased level of mExo1 mRNA was observed during a stage of testis development where cells that are actively involved in meiotic recombination arise first and represent a significant proportion of the germ cell population. Comparative evaluation of the expression patterns of the human and mouse genes, combined with previous biochemical and yeast genetic studies, indicate that the Exo1-like proteins are important contributors to chromosome processing during mammalian DNA repair and recombination.     

Expression of Gtf2ird1, the Williams syndrome-associated gene, during mouse development

The gene GTF2IRD1 is localized within the critical region on chromosome 7 that is deleted in Williams syndrome patients. Genotype-phenotype comparisons of patients carrying variable deletions within this region have implicated GTF2IRD1 and a closely related homolog, GTF2I, as prime candidates for the causation of the principal symptoms of Williams syndrome. We have generated mice with an nls-LacZ knockin mutation of the Gtf2ird1 allele to study its functional role and examine its expression profile. In adults, expression is most prominent in neurons of the central and peripheral nervous system, the retina of the eye, the olfactory epithelium, the spiral ganglion of the cochlea, brown fat adipocytes and to a lesser degree myocytes of the heart and smooth muscle. During development, a dynamic pattern of expression is found predominantly in musculoskeletal tissues, the pituitary, craniofacial tissues, the eyes and tooth buds. Expression of Gtf2ird1 in these tissues correlates with the manifestation of some of the clinical features of Williams syndrome.