牙齿发育相关基因Osr2的生物信息学分析

目的：为生物学实验研究Osr2与牙齿发育的关系提供思路和参考。方法：本文运用生物信息学的同源比对、进化分析等方法,对Osr2及其编码蛋白的生物信息学特征进行分析。结果：结果显示Osr2蛋白质无信号肽,是非跨膜的疏水性蛋白,具有C2H2型、CHY型锌指结构域,是一类进化保守,高度同源的转录因子。结论：这一结果可为Osr2深入的结构与功能分析及利用提供进一步的信息与参考。     

牙齿发育相关基因Osr2 的生物信息学分析

目的:为生物学实验研究Osr2与牙齿发育的关系提供思路和参考.方法:本文运用生物信息学的同源比对、进化分析等方法,对Osr2及其编码蛋白的生物信息学特征进行分析.结果:结果显示Osr2蛋白质无信号肽,是非跨膜的疏水性蛋白,具有C2H2型、CHY型锌指结构域,是一类进化保守,高度同源的转录因子.结论:这一结果可为Osr2深入的结构与功能分析及利用提供进一步的信息与参考.     

Osr1 expression demarcates a multi-potent population of intermediate mesoderm that undergoes progressive restriction to an Osr1-dependent nephron progenitor compartment within the mammalian kidney

The mammalian metanephric kidney is derived from the intermediate mesoderm. In this report, we use molecular fate mapping to demonstrate that the majority of cell types within the metanephric kidney arise from an Osr1⁺ population of metanephric progenitor cells. These include the ureteric epithelium of the collecting duct network, the cap mesenchyme and its nephron epithelia derivatives, the interstitial mesenchyme, vasculature and smooth muscle. Temporal fate mapping shows a progressive restriction of Osr1⁺ cell fates such that at the onset of active nephrogenesis, Osr1 activity is restricted to the Six2⁺ cap mesenchyme nephron progenitors. However, low-level labeling of Osr1⁺ cells suggests that the specification of interstitial mesenchyme and cap mesenchyme progenitors occurs within the Osr1⁺ population prior to the onset of metanephric development. Furthermore, although Osr1⁺ progenitors give rise to much of the kidney, Osr1 function is only essential for the development of the nephron progenitor compartment. These studies provide new insights into the cellular origins of metanephric kidney structures and lend support to a model where Osr1 function is limited to establishing the nephron progenitor pool.     

The Osr1 and Osr2 genes act in the pronephric anlage downstream of retinoic acid signaling and upstream of Wnt2b to maintain pectoral fin development

Vertebrate odd-skipped related genes (Osr) have an essential function during the formation of the intermediate mesoderm (IM) and the kidney structures derived from it. Here, we show that these genes are also crucial for limb bud formation in the adjacent lateral plate mesoderm (LPM). Reduction of zebrafish Osr function impairs fin development by the failure of tbx5a maintenance in the developing pectoral fin bud. Osr morphant embryos show reduced wnt2b expression, and increasing Wnt signaling in Osr morphant embryos partially rescues tbx5a expression. Thus, Osr genes control limb bud development in a non-cell-autonomous manner, probably through the activation of Wnt2b. Finally, we demonstrate that Osr genes are downstream targets of retinoic acid (RA) signaling. Therefore, Osr genes act as a relay within the genetic cascade of fin bud formation: by controlling the expression of the signaling molecule Wnt2ba in the IM they play an essential function transmitting the RA signaling originated in the somites to the LPM.     

A unique mouse strain expressing Cre recombinase for tissue-specific analysis of gene function in palate and kidney development

Mammalian palate development is a multistep process, involving initial bilateral downward outgrowth of the palatal shelves from the oral side of the maxillary processes, followed by stage-specific palatal shelf elevation to the horizontal position above the developing tongue and subsequent fusion of the bilateral palatal shelves at the midline to form the intact roof of the oral cavity. While mutations in many genes have been associated with cleft palate pathogenesis, the molecular mechanisms regulating palatal shelf growth, patterning, and elevation are not well understood. Genetic studies of the molecular mechanisms controlling palate development in mutant mouse models are often complicated by early embryonic lethality or gross craniofacial malformation. We report here the development of a mouse strain for tissue-specific analysis of gene function in palate development. We inserted an IresCre bicistronic expression cassette into the 3' untranslated region of the mouse Osr2 gene through gene targeting. We show, upon crossing to the R26R reporter mice, that Cre expression from the Osr2(IresCre) knockin allele activated beta-galactosidase expression specifically throughout the developing palatal mesenchyme from the onset of palatal shelf outgrowth. In addition, the Osr2(IresCre) mice display exclusive Cre-mediated recombination in the glomeruli tissues derived from the metanephric mesenchyme and complete absence of Cre activity in other epithelial and mesenchymal tissues in the developing metanephric kidney. These data indicate that the Osr2(IresCre) knockin mice provide a unique tool for tissue-specific studies of the molecular mechanisms regulating palate and kidney development.     

Odd-skipped related 2 regulates genes related to proliferation and development

Cell proliferation is a biological process in which chromosomes replicate in one cell and equally divide into two daughter cells. Our previous findings suggested that Odd-skipped related 2 (Osr2) plays an important role in cellular quiescence and proliferation under epigenetic regulation. However, the mechanism used by Osr2 to establish and maintain proliferation is unknown. To examine the functional role of Osr2 in cell proliferation, we analyzed its downstream target genes using microarray analysis following adenovirus-induced overexpression of Osr2 as well as knockdown with Osr2 siRNA, which showed that Osr2 regulates a multitude of genes involved in proliferation and the cell cycle, as well as development. Additional proliferation assays also indicated that Osr2 likely functions to elicit cell proliferation. Together, these results suggest that Osr2 plays important roles in proliferation and development.     

Molecular cloning and expression of the col2a1a and col2a1b genes in the medaka, Oryzias latipes

The Col2a1 gene is expressed in notochord, otic vesicle, cartilaginous tissue and the anlage of endochondral bone during development in higher vertebrates. Type II collagen, a homotrimeric product of the Col2a1 gene, functions as a key regulatory protein for cartilage development and endochondral ossification. In medaka and zebrafish, a single homolog of the col2a1 gene has been identified. However, it is necessary to note that many genes are duplicated in teleost fishes. To clarify function of col2a1 genes in teleost fishes and to further understand the process of cartilage development and endochondral ossification, we cloned and mapped the gene loci of two col2a1 orthologs in medaka. The proteins encoded by both medaka col2a1a and col2a1b genes were highly conserved (85.3% and 82.6%) relative to human COL2A1, but synteny was not observed. We also examined the expression patterns of col2a1a and col2a1b during embryonic development. Whole-mount insitu hybridization data suggests that expression patterns of both medaka co2a1a and col2a1b genes are similar to that of zebrafish co2a1 in the early embryonic stages. In medaka, the two col2a1 genes show a closely correlated pattern of spatial and temporal expression. In late embryonic stages, however, there were differences in both expression patterns in the pectoral fin. This study is the first report of two homologs of col2a1 in teleosts and also the first examination of col2a1a and col2a1b expression patterns in this group.     

Developmentally regulated demethylase activity targeting the betaA-globin gene in primary avian erythroid cells

Differential expression of globin genes has provided an interesting model system for better understanding commonly inherited diseases such as thalassemia. In the avian beta-type globin cluster (5'-rho-betaH-betaA-epsilon-3'), silencing of the embryonic rho-globin gene occurs concomitantly with the activation of the adult betaA-globin gene during embryonic development. DNA methylation is a dynamic process that regulates gene expression. We observed a progressive loss of methylation of betaA-globin gene, during avian embryonic development that was concurrent with the expression of the gene. The promoter and exon 1 regions of the template strand were completely demethylated, whereas residual methylation was retained in exons 2 and 3. Using a modified methylation-sensitive single-nucleotide primer extension (MS-SNuPE) assay, we observed stage-specific demethylase activity in the nuclear extracts of chicken red cells; activity in 5-, 8-, and 11-day-old erythroid cell nuclear extracts was 6, 76, and 24%, respectively. The demethylase targeted both hemimethylated and fully methylated substrates. Our findings demonstrate stage-specific demethylase activity in nuclear extracts from primary chicken erythroid cells that could target the fully methylated promoter of a developmentally regulated native gene.