Expression patterns of sulfatase genes in the developing mouse embryo

Mammalian sulfatase enzymes participate in various processes, such as hormone regulation, lysosomal degradation and modulation of several signaling pathways. The sulfatase gene family consists of 14 members in mice and 17 in humans. Mutations of at least eight members are associated with human disorders, with main disease manifestations in the nervous system and skeleton. Despite their biological significance, little is known about their expression during embryonic development, especially for the more recently discovered gene family members. By in situ hybridization, we compared the expression patterns of nine sulfatases: ArsB, ArsG, ArsI, ArsJ, Galns, Gns, Ids, Sulf1, and Sulf2 in midgestation mouse embryos. Of interest, overlapping expression domains of several sulfatases could be detected in the developing central nervous system, eye, skeleton, and inner organs. Moreover, novel expression patterns for ArsG in choroid plexus, ArsI in hypertrophic chondrocytes and ArsJ in joints were identified. Developmental Dynamics 239:1779–1788, 2010. © 2010 Wiley‐Liss, Inc.     

Expression patterns of the Wtx/Amer gene family during mouse embryonic development

WTX/AMER1 is a novel negative regulator of the WNT/β‐catenin pathway with mutations detected in Wilms' tumors and an X‐linked sclerosing bone dysplasia. WTX/AMER1 (Fam123b) shares several domains of homology with two other recently identified proteins: AMER2 (Fam123a) and AMER3 (Fam123c). Here, we describe an in‐depth expression analysis of all three members of this gene family during mouse embryonic development. All genes were strongly expressed in the central as well as the peripheral nervous system, thus suggesting important roles of this gene family during neurogenesis. Specific expression was found in the retina, inner ear, and nasal epithelium. Outside of the nervous system Wtx/Amer1 showed the broadest expression domains including cephalic and limb mesenchyme, skeletal muscle, bladder, gonads, lung bud, salivary glands, and the kidneys. The widespread expression pattern of Wtx/Amer1, together with its role as a modulator of the Wnt signaling pathway, suggest that Wtx/Amer1 serves pleiotropic roles during mammalian organogenesis. Developmental Dynamics 239:1867–1878, 2010. © 2010 Wiley‐Liss, Inc.     

Expression patterns of ShcD and Shc family adaptor proteins during mouse embryonic development

The Src homology and collagen (Shc) proteins function as molecular adaptors in signaling pathways mediated by a variety of cell surface receptors. Of the four mammalian Shc proteins, ShcD is the least characterized. To this end, ShcD expression was documented and compared to that of other Shc family proteins. In the developing mouse embryo, expression of ShcD overlaps with that of other Shc proteins in the central nervous system, with specific distribution in post‐mitotic neurons. In addition, robust ShcD expression is seen within differentiated epithelial cells of several organs, as well as in skeletal and cardiac muscle, and various tissues of neural crest origin. Interestingly, all Shc family members are expressed in hypertrophic chondrocytes, the first report of Shc protein expression in the developing skeleton. The unique tissue distribution patterns of Shc proteins likely contribute to their complex tissue‐specific signaling functions during embryogenesis. Developmental Dynamics, 2011. © 2010 Wiley‐Liss, Inc.     

Expression of seven members of the ADAM family in developing chicken spinal cord

The expression patterns of seven members of the ADAM (a disintegrin and metalloprotease) family, including ADAM9, ADAM10, ADAM12, ADAM13, ADAM17, ADAM22, and ADAM23, were analyzed in the developing chicken lumbar spinal cord by in situ hybridization and immunohistochemistry. Results show that each individual ADAM is expressed and regulated spatiotemporally in the lumbar cord and its surrounding tissues. ADAM9, ADAM10, ADAM22, and ADAM23 are expressed predominantly by motoneurons in the motor column and by sensory neurons in the dorsal root ganglia, each with a different expression pattern. ADAM12 and ADAM13 are mainly expressed in the meninges around the lumbar cord and in the condensed sheets of chondroblasts around the vertebrae. ADAM17 expression is strong in the ventricular layer and limited to early stages. The differential expression of the ADAMs in the lumbar cord suggests that the ADAMs play a regulatory role in development of the spinal cord. Developmental Dynamics 239:1246–1254, 2010. © 2010 Wiley‐Liss, Inc.     

胰岛素增强子结合蛋白1在小鼠胚胎心的时空分布

目的 观察转录因子胰岛素增强子结合蛋白1（ISL1）在小鼠胚胎心的表达与心、第二生心区及前肠内胚层的发育。 方法 胚龄8～13d小鼠胚胎心共18个,连续石蜡切片,用抗心肌肌球蛋白重链（MHC）、抗ISL1、抗增殖细胞核抗原（PCNA）和抗α-平滑肌肌动蛋白(α-SMA)抗体进行免疫组织化学染色、免疫荧光染色和Western blotting检测。 结果 胚龄9d,ISL1阳性心前体细胞进入流出道远端。胚龄10d,ISL1阳性细胞延伸入流出道近端及静脉窦心肌。胚龄11～12d,心内ISL1表达量逐渐增多并达高峰,动脉端ISL1阳性细胞分布于流出道远端壁、心包内主肺动脉壁及主肺动脉隔,静脉端ISL1阳性细胞主要限于窦房结和静脉瓣。动脉端前肠内胚层细胞索增至最长,周围前生心区ISL1阳性细胞密度也达高峰,并且明显多于后生心区。胚龄13d,心内及第二生心区ISL1阳性细胞显著减少,内胚层细胞索趋于消失。 结论 ISL1阳性细胞在小鼠胚胎心的表达主要集中在胚龄9～13d,其表达模式与第二生心区及前肠内胚层的发育密切相关。     

Enforced expression of the transcription factor HOXD3 under the control of the Wnt1 regulatory element modulates cell adhesion properties in the developing mouse neural tube

HOX genes expressed in a specific spatial and temporal manner play a crucial role in determining the body plan during the early development of vertebrates. In adult tissues, many HOX genes participate in normal hematopoiesis and carcinogenesis. We previously found that overexpression of the homeobox gene HOXD3 alters expression levels of cell adhesion molecules in human cancer cell lines. Here, we have investigated whether HOXD3 expression is related to the cell adhesion processes during mouse development focusing on dorsal midline cells or roof-plate cells of the neural tube and neural crest cells. We created transgenic mouse embryos, in which HOXD3 is expressed in the dorsal midline under the control of the Wnt1 regulatory element, and analyzed these embryos at embryonic day 10.5-13.5. In HOXD3-expressing transgenic embryos, although neural crest-derived structures in the trunk region appeared to be normal, striking abnormalities were found in the neural tube. In transgenic embryos expressing the lacZ gene under the control of the Wnt1 regulatory element, expression of lacZ was restricted to roof-plate cells within the neural tube. By contrast, in HOXD3-expressing transgenic embryos, expression of HOXD3 was not only located in the dorsal neural tube, but also had spread inside the ventricular zone in more ventral regions of the neural tube. These findings show that the HOXD3 transgene is expressed more broadly than the Wnt1 gene is normally expressed. Expression of both Wnt1 and Msx1, marker genes in the roof plate, was further extended ventrally in HOXD3-expressing embryos than in normal embryos, suggesting that expression of the HOXD3 transgene expands the roof plate ventrally within the neural tube. In the ventricular zone of HOXD3-expressing embryos at embryonic day 10.5, we observed an increase in the number of mitotic cells and failure of interkinetic nuclear migration of progenitor cells. Furthermore, in HOXD3-expressing embryos at embryonic day 12.5, the ventricular zone, in which progenitor cells became more loosely connected to each other, was composed of a large number of cells that did not express N-cadherin. Our results indicate that expression of HOXD3 is closely associated with modulation of cell-adhesive properties during embryonic development.     

Expression of the Wnt gene family during late nephrogenesis and complete ureteral obstruction.

Because the Wnt-4, -7b, and -11 genes are expressed in metanephric kidneys and code for secreted glycoproteins that may serve as mediators of the transformation of renal mesenchyme to epithelium, we investigated the pattern of Wnt gene expression in late metanephrogenesis and after ureteral obstruction. Newborn and 10-, 20-, and 60-day-old rats underwent complete unilateral ureteral ligation or sham operation. The kidneys were collected bilaterally 1, 5, 10, 20, or 30 days later. RNase protection assays were used to quantify the amounts of mRNA encoding Wnt-4, -7b, and -11, E-cadherin, and cytokeratin-19. Renal development was assessed by histologic characterization of vimentin, cytokeratin, E-cadherin, and beta-catenin distribution. During normal development, the amounts of mRNA encoding Wnt-4 and Wnt-11 increased during gestation and then abruptly decreased after the completion of metanephrogenesis, 15 days after birth. In contrast, the amounts of mRNA encoding Wnt-7b, E-cadherin, and cytokeratin-19 increased during development and into adulthood. In neonatally obstructed kidneys, the expression of Wnt-4 was abnormally maintained when obstruction was induced before the completion of renal development and was reactivated when obstruction was induced after the completion of metanephrogenesis. Wnt-7b expression was minimally affected and Wnt-11 expression was only transiently affected by obstruction. In neonatally obstructed kidneys, the differentiation of mesenchyme to epithelium failed to proceed normally, with the majority of cells maintaining vimentin expression and some differentiated epithelial cells reverting to vimentin expression. In addition, the expression of E-cadherin and cytokeratin was increased in epithelial cells. Changes in the expression of Wnt genes were correlated with histologic changes. This study suggests that Wnt-4 and -11 are likely to be important mediators of the transformation of mesenchyme to epithelium in the kidney. Obstruction induced during metanephrogenesis disrupts the normal pattern of Wnt-4, -7b, and -11 expression and interferes with the normal transformation process in developing kidneys, by maintaining the mesenchymal component and inducing the transformation of epithelium to mesenchyme.     

Ultrastructural observations on cell necrosis during formation of the neural tube in mouse embryos

Summary Spontaneous cell death in the developing brain of 8.5–9 day old mouse embryos has been investigated with the electron microscope. Before closure of the neural tube, areas of cell death are found at the neuro-somatic junction. After closure of the neural tube degenerating cells are found in the dorsal midline of the prospective diencephalon. Ultrastructurally, cell degeneration is marked by chromatin condensation, increase in electron density of the structures in the cytoplasm and, in later stages, by a marked pycnosis of the dying cell. After fragmentation, the necrotic material as well as entire pycnotic cells are phagocytized and digested by cells of the neuroepithelium. An invasion of macrophages has not been observed. The significance of cell necrosis is discussed in relation to the normal formation of the neural tube and to the occurrence of certain induced malformations (exencephalies).     

Expression patterns of the lysophospholipid receptor genes during mouse early development

Lysophospholipids (LPs) such as lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) are known to mediate various biological responses, including cell proliferation, migration, and differentiation. To better understand the role of these lipids in mammalian early development, we applied whole-mount in situ hybridization techniques to E8.5 to E12.5 mouse embryos. We determined the expression patterns of the following LP receptor genes, which belong to the G protein-coupled receptor (GPCR) family: EDG1 to EDG8 (S1P1 to S1P5 and LPA1 to LPA3), LPA4 (GPR23/P2Y9), and LPA5 (GPR92). We found that the S1P/LPA receptor genes exhibit overlapping expression patterns in a variety of organ primordia, including the developing brain and cardiovascular system, presomitic mesoderm and somites, branchial arches, and limb buds. These results suggest that multiple receptor systems for LPA/S1P lysophospholipids may be functioning during organogenesis.     

Spatial and temporal distribution patterns of enkephalinergic neurons in adult and developing retinas of the preproenkephalin-green fluorescent protein transgenic mouse

Enkephalin (ENK) peptides are present in the retina of several vertebrate species and play a crucial role in establishing specific circuits during retinal development. However, there is no information available concerning the development of ENKergic neurons in the mouse retina. To address this question, we used preproenkephalin-enhanced green fluorescent protein (GFP) transgenic mice, in which ENKergic neurons are revealed by GFP. Our results showed that most GFP-positive cells were located in the proximal part of the inner nuclear layer with a scattering of GFP-immunoreactive cells in the ganglion cell layer (GCL) in the adult retina. Double immunostaining with syntaxin indicates that GFP expression was restricted to a population of amacrine cells. The proportions of glycine transporter-1 and γ-aminobutyric acid-positive cells among ENKergic neurons were 57.3 ± 2.4% and 10.1 ± 1.8%, respectively. We then injected retrograde tracer into the superior colliculus and observed that none of the ENKergic neurons in the GCL were retrogradely labeled with the tracer. GFP-positive cells were first observed at embryonic day (E) 15 in the inner neuroblastic layer at only very low levels, which gradually increased until E18. After birth, there was a steep rise in GFP expression levels, reaching maximal activity by postnatal day (P) 7. The distribution and intensity of GFP-positive cells at P15 were similar to those of adult retina. It was found that immunoreactive processes in the inner plexiform layer formed strongly stained patches. The present results provide detailed morphological evidence of the cell type and spatial and temporal distribution of ENKergic neurons in the retina.     

Wnt信号通路与神经管缺陷关系的研究进展

神经管缺陷(neural tube,defects,NTD)是神经管闭合不全引起的一类先天性畸形,主要包括无脑、脑膨出、脑膜膨出和脊柱裂等.研究神经管发育机制及NTD致畸机制对预防畸形发生有一定的意义.Wnt信号通路在神经管发育过程中发挥重要的作用,不但参与了胚胎背腹轴的形成,而且与细胞极性建立、细胞命运决定等多个发育事件有关.阻断Wnt信号途径,动物胚胎会产生明显的突变表型,如果蝇的异常表皮、小鼠腹侧化肢体、线虫EMS细胞丧失不对称分裂等.近来研究发现,Wnt信号通路异常与神经管畸形发生密切相关,Wnt信号通路某一环节发生异常或中断都可能导致畸形的发生.     

Expression patterns of nectins and afadin during epithelial remodeling in the mouse embryo.

Cell-cell adhesion plays key roles in tissue morphogenesis and organogenesis. Nectins are Ca2+-independent immunoglobulin-like cell adhesion molecules connected to the actin cytoskeleton through afadin. Nectins play roles in a variety of cell-cell junctions in cooperation with or independently of cadherins. Here, we examined the cellular localization of nectins and afadin throughout primitive streak, neural plate, and early organogenesis stages of mouse development. Nectin and afadin localization coincided with a honeycomb-shaped meshwork of actin filaments at adherens junctions of polarized epithelia, including neuroepithelium, epithelial somites, and facial primordia. As organogenesis progressed, nectin-2 expression was maintained in general columnar epithelia, whereas nectin-1 and -3 became highly concentrated at sites of neural morphogenesis. Moreover, nectin-1 was highly expressed in keratinocytes of the skin, developing hair follicles, and epithelium of developing teeth. These results suggest that nectins and afadin are involved in dynamic epithelial remodeling during mouse development.