PCP4 is highly expressed in ectoderm and particularly in neuroectoderm derivatives during mouse embryogenesis

PCP4 (PEP-19) belongs to a family of proteins involved in calcium transduction signals and binds calmodulin via an IQ motif, in a calcium independent manner. PCP4 gene maps to murine chromosome 16 and in human to chromosome 21. Murine PCP4 expression in the brain has been detected by Northern blot analysis to be mainly post-natal and in the adult to have a neuronal pattern. To investigate if it might have a role earlier in development, we analyzed its expression during mouse embryogenesis by in situ hybridization from E7.5 post-coitum (p.c.) to E17.5 p.c., and in P0 brain. Early, at E7.5, a high expression is restricted to the extra embryonic ectoderm. Embryonic expression starts at E9.5. At E10.5, PCP4 shows a strong signal in the post-mitotic cells of the diencephalon, the metencephalon and the myelencephalon and in the dorsal and cranial ganglia. The floor plate is also densely labelled. At E17.5, PCP4 is expressed in the central nervous system, in the myenteric plexus, and in other ectoderm derivatives, for instance the lens, the hairy cells of the cochlea, the enamel organ and the hair follicles. Thus, during embryogenesis PCP4 is mainly expressed in ectoderm and neuroectoderm comprising neural crest derived cells.     

Development of the noradrenergic system of the rat brain after prenatal exposure to corticosterone

The influence of corticosterone during the period of tyrosine hydroxylase gene expression (16th–18th days of rat embryogenesis), which is sensitive to hormonal induction, on the ontogenesis of presynaptic markers of the noradrenergic system has been studied. It has been found that hormone-induced changes in the level of noradrenaline and dopamine in the brain cortex and brainstem had a transitive character and were eliminated in adulthood. At the same time, the hormone increased the activity of tyrosine hydroxylase in the cortex of 7- to 16-day-old rat pups and in the cortex and brainstem of adult animals. It has been shown that the level of glucocorticoids is an important factor in development of the noradrenergic system of the brain, able during critical periods of ontogenesis to cause sustained changes of its functioning in subsequent periods of life.     

Chondromodulin I is a bone remodeling factor

Chondromodulin I (ChM-I) was supposed from its limited expression in cartilage and its functions in cultured chondrocytes as a major regulator in cartilage development. Here, we generated mice deficient in ChM-I by targeted disruption of the ChM-I gene. No overt abnormality was detected in endochondral bone formation during embryogenesis and cartilage development during growth stages of ChM-I(-/-) mice. However, a significant increase in bone mineral density with lowered bone resorption with respect to formation was unexpectedly found in adult ChM-I(-/-) mice. Thus, the present study established that ChM-I is a bone remodeling factor.     

Ontogenetic and tissue-specific expression of gonadotropin-inhibitory hormone (GnIH) and its receptors in Catla catla

Gonadotropin-inhibitory hormone (GnIH) is an RFamide peptide, and its role in reproduction is well studied from fish to mammals, but very few reports are available about the function of GnIH during larval development. In this study, we examined the GnIH and GnIH receptors (GnIHRs) expression from embryogenesis to adult stage and tissue-specific expression in adult Catla catla using quantitative real-time (qRT) PCR. The qRT PCR analysis of GnIH mRNA during ontogenetic development showed the increasing trend from early developmental stages to the adult stage with the highest expression in 24 months fish. However, the expression of two GnIH receptors, GnIHR1 and GnIHR2 also increased from larval stages to the adults with a peak at 17 days post-hatching, while GnIHR3 showed the higher mRNA expression during embryogenesis and then decreasing gradually. Tissue distribution analysis of GnIH showed the highest mRNA expression of GnIH in the brain, followed by gonads of both the sexes. GnIHR1 and GnIHR2 were also highly expressed in the brain and gonads of both the sexes, while GnIHR3 showed the highest expression in gonads of both the sexes without any expression in the brain. These results suggest that the brain is the primary site of action for GnIH, GnIHR1 and GnIHR2, while gonads for GnIHR3.

     

Developmental and spatial expression pattern of syntaxin 13 in the mouse central nervous system

Vesicular transport involves SNARE (soluble- N-ethylmaleimide-sensitive-factor-attachment-protein-receptor) proteins on transport vesicles and on target membranes. Syntaxin 13 is a SNARE enriched in brain, associated with recycling endosomes; its overexpression in PC12 cells promotes neurite outgrowth. This suggests an important role for receptor recycling during neuronal differentiation. Here we describe the spatiotemporal pattern of syntaxin 13 expression during mouse brain development. During early embryogenesis (E12-E15), it was found in the forebrain ventricular zone and in primary motor and sensory neurons in the brainstem, spinal cord and sensory ganglia. In the forebrain at E15, syntaxin 13 was not detected in neuroblasts in the intermediate zone of the embryonic hemispheric wall, while there was labeling in cortical neurons in deeper layers starting at E15-18, and progressively in later-generated neurons up to layer II around P6. Syntaxin 13 reached maximal expression in all brain divisions at about P7, followed by a decrease, with heterogeneous neuron populations displaying various staining intensities in adult brain. While usually restricted to the soma of neurons, we transiently detected syntaxin 13 in dendrites of pyramidal neurons during the first postnatal week. In conclusion, the developmentally regulated syntaxin 13 expression in various neuronal populations is consistent with its involvement in endocytic trafficking and neurite outgrowth.     

Fibroblast growth factor 2 internal ribosome entry site (IRES) activity ex vivo and in transgenic mice reveals a stringent tissue-specific regulation

Fibroblast growth factor 2 (FGF-2) is a powerful mitogen involved in proliferation, differentiation, and survival of various cells including neurons. FGF-2 expression is translationally regulated; in particular, the FGF-2 mRNA contains an internal ribosome entry site (IRES) allowing cap-independent translation. Here, we have analyzed FGF-2 IRES tissue specificity ex vivo and in vivo by using a dual luciferase bicistronic vector. This IRES was active in most transiently transfected human and nonhuman cell types, with a higher activity in p53 -/- osteosarcoma and neuroblastoma cell lines. Transgenic mice were generated using bicistronic transgenes with FGF-2 IRES or encephalomyocarditis virus (EMCV) IRES. Measurements of luciferase activity revealed high FGF-2 IRES activity in 11-d-old embryos (E11) but not in the placenta; activity was high in the heart and brain of E16. FGF-2 IRES activity was low in most organs of the adult, but exceptionally high in the brain. Such spatiotemporal variations were not observed with the EMCV IRES. These data, demonstrating the strong tissue specificity of a mammalian IRES in vivo, suggest a pivotal role of translational IRES- dependent activation of FGF-2 expression during embryogenesis and in adult brain. FGF-2 IRES could constitute, thus, a powerful tool for gene transfer in the central nervous system.     

A Caenorhabditis elegans wee1 homolog is expressed in a temporally and spatially restricted pattern during embryonic development

A wee1 homolog, wee-1.1, is expressed in both a temporally and spatially restricted pattern during early Caenorhabditis elegans embryogenesis, and is undetectable throughout the remainder of embryogenesis. The wee-1.1 message appears to be zygotically expressed in the somatic founder cell E of the 12-cell embryo. This expression disappears when the E blastomere divides for the first time. The wee-1.1 message then appears transiently in the nuclei of the eight great-granddaughter cells of the AB somatic founder cell, just before these cells divide in the 16-cell embryo. Following this division, the wee-1.1 mRNA is no longer detectable throughout the remainder of embryogenesis. The expression of wee-1.1 in the E blastomere and in the AB progeny appears to be restricted to nuclei in prophase and metaphase of the cell cycle. Analysis of the wee-1.1 mRNA expression pattern in maternal-effect lethal mutants suggests that this expression pattern is restricted to cells of the E and AB fates in the early embryo. This mRNA expression pattern is restricted to a 10-15-min span of embryonic development and may be regulating the timing of crucial cell divisions at this early stage of development.     

Quantitative analysis of nerve growth factor in the amniotic fluid during chick embryonic development

Nerve growth factor (NGF) and most neurotrophic factors support the proliferation and survival of particular types of neurons. Besidesthe pivotal role of NGF in the development of neuronal cells, it also has important functions on non-neuronal cells. The amnion surrounds the embryo, providing an aqueous environment for the embryo. A wide range of proteins has been identified in human amniotic fluid (AF). In this study, total protein concentration (TPC) and NGF level in AF samples from chick embryos were measured using a Bio-Rad protein assay, enzyme linked immunosorbent assay (ELISA) and Western blot. TPC increased from days E10 to day E18. There was a rapid increase in AF TPC on day E15 when compared to day E16. No significant changes in NGF levels have been seen from day E10 to day E14. There was a rapid increase in NGF content on days E15 and E16, and thereafter the levels decreased from day E16 to day E18. Since, NGF is important in brain development and changes in AF NGF levels have been seen in some CNS malformations, changes in the TPC and NGF levels in AF during chick embryonic development may be correlated with cerebral cortical development. It is also concluded that NGF is a constant component of the AF during chick embryogenesis.     

血管内皮生长因子的脑保护及其机制研究进展

血管内皮生长因子(vascular endothelial growth factor,VEGF)是一种重要的血管发育调节因子,最早发现于肿瘤细胞。上世纪90年代,人们发现VEGF在神经细胞上也有广泛表达,并具有神经细胞保护作用。此外,VEGF显著促进成年哺乳动物结构性神经元再生区(constitutive neurogenic regions)和非神经元再生区(non-neurogenic regions)的神经元再生/更新(neurogenesis/regenera-tion),显示了VEGF在神经损伤性及退行性疾病治疗中的潜在意义。本文着重讨论VEGF在脑缺血损伤中的神经保护(neuroprotection)和神经修复(neural repair)及其细胞和分子机制研究进展。     

Correlation of Versican Expression,Accumulation, and Degradation during Embryonic Development by Quantitative Immunohistochemistry

Versican, a chondroitin sulfate proteoglycan, is important in embryonic development, and disruption of the versican gene is embryonically lethal in the mouse. Although several studies show that versican is increased in various organs during development, a focused quantitative study on versican expression and distribution during lung and central nervous system development in the mouse has not previously been performed. We tracked changes in versican (Vcan) gene expression and in the accumulation and degradation of versican. Vcan expression and quantitative immunohistochemistry performed from embryonic day (E) 11.5 to E15.5 showed peak Vcan expression at E13.5 in the lungs and brain. Quantitative mRNA analysis and versican immunohistochemistry showed differences in the expression of the versican isoforms in the embryonic lung and head. The expression of Vcan mRNA and accumulation of versican in tissues was complementary. Immunohistochemistry demonstrated co-localization of versican accumulation and degradation, suggesting distinct roles of versican deposition and degradation in embryogenesis. Very little versican mRNA or protein was found in the lungs of 12- to 16-week-old mice but versican accumulation was significantly increased in mice with Pseudomonas aeruginosa lung infection. These data suggest that versican plays an important role in fundamental, overlapping cellular processes in lung development and infection.     

The role of phospholipid hydroperoxide glutathione peroxidase isoforms in murine embryogenesis

Phospholipid hydroperoxide glutathione peroxidase (GPx4) is a selenocysteine-containing enzyme, and three different isoforms (cytosolic, mitochondrial, and nuclear) originate from the GPx4 gene. Homozygous GPx4-deficient mice die in utero at midgestation, since they fail to initiate gastrulation and do not develop embryonic cavities. To investigate the biological basis for embryonic lethality, we first explored expression of the GPx4 in adult murine brain and found expression of the protein in cerebral neurons. Next, we profiled mRNA expression during the time course of embryogenesis (embryonic days 6.5-17.5 (E6.5-17.5)) and detected mitochondrial and cytosolic mRNA species at high concentrations. In contrast, the nuclear isoform was only expressed in small amounts. Cytosolic GPx4 mRNA was present at constant levels (about 100 copies per 1000 copies of glyceraldehyde-3-phosphate dehydrogenase mRNA), whereas nuclear and mitochondrial isoforms were down-regulated between E14.5 and E17.5. In situ hybridization indicated expression of GPx4 isoforms in all developing germ layers during gastrulation and in the somite stage in the developing central nervous system and in the heart. When we silenced expression of GPx4 isoforms during in vitro embryogenesis using short interfering RNA technology, we observed that knockdown of mitochondrial GPx4 strongly impaired segmentation of rhombomeres 5 and 6 during hindbrain development and induced cerebral apoptosis. In contrast, silencing expression of the nuclear isoform led to retardations in atrium formation. Taken together, our data indicate specific expression of GPx4 isoforms in embryonic brain and heart and strongly suggest a role of this enzyme in organogenesis. These findings may explain in part intrauterine lethality of GPx4 knock-out mice.