43 research outputs found
Targeted disruption of the even-skipped gene, evx1, causes early postimplantation lethality of the mouse conceptus.
Journal ArticleImplantation within the mammalian uterus elicits dramatic changes in the growth, differentiation, and morphogenesis of the conceptus. This process is interrupted in mice carrying a targeted disruption of the murine evx1 gene, a homolog of the Drosophila even-skipped (eve) gene. Upon implantation, presumptive evx1- homozygotes elicit a decidual response, invade the uterine epithelium, and attach to the basement membrane between uterine stroma and epithelium, but fail to differentiate extraembryonic tissues or to form egg cylinders prior to resorption. Retrograde analysis of embryo genotypes demonstrates that homozygotes could be isolated as free-floating blastocysts but not as gastrulating egg cylinders. Homozygous mutant blastocysts appeared normal and, when grown in vitro, attach, proliferate, and form trophoblastic giant cells surrounding a growing inner cell mass before rapidly degenerating. In situ hybridization analysis demonstrates evx1 gene expression within the visceral endoderm after implantation and prior to gastrulation, at a time in which the mutant phenotype is first detected
Targeted disruption of cubilin reveals essential developmental roles in the structure and function of endoderm and in somite formation
BACKGROUND: Cubilin is a peripheral membrane protein that interacts with the integral membrane proteins megalin and amnionless to mediate ligand endocytosis by absorptive epithelia such as the extraembryonic visceral endoderm (VE). RESULTS: Here we report the effects of the genetic deletion of cubilin on mouse embryonic development. Cubilin gene deletion is homozygous embryonic lethal with death occurring between 7.5–13.5 days post coitum (dpc). Cubilin-deficient embryos display developmental retardation and do not advance morphologically beyond the gross appearance of wild-type 8–8.5 dpc embryos. While mesodermal structures such as the allantois and the heart are formed in cubilin mutants, other mesoderm-derived tissues are anomalous or absent. Yolk sac blood islands are formed in cubilin mutants but are unusually large, and the yolk sac blood vessels fail to undergo remodeling. Furthermore, somite formation does not occur in cubilin mutants. Morphological abnormalities of endoderm occur in cubilin mutants and include a stratified epithelium in place of the normally simple columnar VE epithelium and a stratified cuboidal epithelium in place of the normally simple squamous epithelium of the definitive endoderm. Cubilin-deficient VE is also functionally defective, unable to mediate uptake of maternally derived high-density lipoprotein (HDL). CONCLUSION: In summary, cubilin is required for embryonic development and is essential for the formation of somites, definitive endoderm and VE and for the absorptive function of VE including the process of maternal-embryo transport of HDL
Efficient method of genotyping ob/ob mice using high resolution melting analysis.
OBJECTIVE: Direct health care costs of obesity continue to grow throughout the world and research on obesity disease models are on the rise. The ob/ob mouse is a well-characterized model of obesity and associated risk factors. Successful breeding and backcrossing onto different backgrounds are essential to create knockout models. Ob/ob mice are sterile and heterozygotes must be identified by genotyping to maintain breeding colonies. Several methods are employed to detect the ob mutant allele, a single nucleotide polymorphism (SNP). Gel based methods are time consuming and inconsistent, and non-gel based assays rely upon expensive and complex reagents or instruments. A fast, high-throughput, cost effective, and consistent method to identify Lep(ob) mutation is much needed. DESIGN AND METHODS: Primers to produce an amplicon for High Resolution Melting Analysis (HRM) of the Lep(ob) SNP were designed and validated. RESULTS: Fluorescence normalized high resolution melting curve plots delineated ob/+, ob/ob, and WT genotypes. Genotypes were also confirmed phenotypically. CONCLUSIONS: HRM of the Lep(ob) SNP allows closed-tube identification of the Lep(ob) mutation using a real-time PCR machine now common to most labs/departments. Advantages of this method include assay sensitivity/accuracy, low cost dyes, less optimization, and cost effectiveness as compared to other genotyping techniques
Hypoxia Up-Regulates Expression of Hemoglobin in Alveolar Epithelial Cells
Alveolar epithelial cells are directly exposed to acute and chronic fluctuations in alveolar oxygen tension. Previously, we found that the oxygen-binding protein hemoglobin is expressed in alveolar Type II cells (ATII). Here, we report that ATII cells also express a number of highly specific transcription factors and other genes normally associated with hemoglobin biosynthesis in erythroid precursors. Because hypoxia-inducible factors (HIFs) were shown to play a role in hypoxia-induced changes in ATII homeostasis, we hypothesized that the hypoxia-induced increase in intracellular HIF exerts a concomitant effect on ATII hemoglobin expression. Treatment of cells from the ATII-like immortalized mouse lung epithelial cell line-15 (MLE-15) with hypoxia for 20 hours resulted in dramatic increases in cellular levels of HIF-2α protein and parallel significant increases in hemoglobin messenger RNA (mRNA) and protein expression, as compared with that of control cells cultured in normoxia. Significant increases in the mRNA of globin-associated transcription factors were also observed, and RNA interference (RNAi) experiments demonstrated that the expression of hemoglobin is at least partially dependent on the cellular levels of globin-associated transcription factor isoform 1 (GATA-1). Conversely, levels of prosurfactant proteins B and C significantly decreased in the same cells after exposure to hypoxia. The treatment of MLE-15 cells cultured in normoxia with prolyl 4-hydroxylase inhibitors, which mimic the effects of hypoxia, resulted in increases of hemoglobin and decreases of surfactant proteins. Taken together, these results suggest a relationship between hypoxia, HIFs, and the expression of hemoglobin, and imply that hemoglobin may be involved in the oxygen-sensing pathway in alveolar epithelial cells
Fluorescence normalized high resolution melting curves of wild type (red), ob/ob (green), and ob/+ (blue) animals.
<p>Fluorescence normalized high resolution melting curves of wild type (red), ob/ob (green), and ob/+ (blue) animals.</p
Confirmation of HRM results by alternate gel-based methods.
<p>Locus specific control band at 191<sup>st</sup> lane and Lep<sup>ob</sup> specifc band at 123bp in 2<sup>nd</sup> lane of pairs.</p
Ob forward and reverse primer sequences for HRM.
<p>Ob forward and reverse primer sequences for HRM.</p