Aberrant Activation of Notch1 Signaling in Glomerular Endothelium Induces Albuminuria.

Rationale: Glomerular capillaries are lined with a highly specialized fenestrated endothelium and contribute to the glomerular filtration barrier. The Notch signaling pathway is involved in regulation of glomerular filtration barrier, but its role in glomerular endothelium has not been investigated due to the embryonic lethality of animal models with genetic modification of Notch pathway components in the endothelium.

Objective: To determine the effects of aberrant activation of the Notch signaling in glomerular endothelium and the underlying molecular mechanisms.

Notch1 activates angiogenic regulator Netrin4 in endothelial cells.

Netrin4 (NTN4) is a chemotropic factor that regulates angiogenesis. We found that endothelial expression of the activated, intracellular domain of Notch1 (NICD1), significantly up-regulated NTN4 mRNA as well as intracellular NTN4 protein in both transgenic mice and cultured human umbilical vein endothelial cells (HUVECs). Notch1 activation also increased NTN4 secretion from HUVECs.

The role of Notch signalling in ovarian angiogenesis.

In adults, the ovary is characterized with extensive angiogenesis and regular intervals of rapid growth. Ovarian function is dependent on the network of angiogenic vessels which enable the follicle and/or corpus luteum to receive oxygen, nutrients and hormonal support. Abnormal angiogenesis is involved in the induction and development of pathological ovary, such as polycystic ovary syndrome and ovarian cancer.

Catalpol downregulates vascular endothelial‑cadherin expression and induces vascular hyperpermeability.

Catalpol, an iridiod glucoside isolated from Rehmannia glutinosa, has been reported to possess anti‑inflammatory properties. However, the molecular mechanisms underlying this effect have not been fully elucidated. This study aimed to investigate the effects of catalpol on vascular permeability.

Trichostatin A suppresses lung adenocarcinoma development in Grg1 overexpressing transgenic mice.

Trichostatin A (TSA) is a histone deacetylase inhibitor and a potential therapeutic for various malignancies. The in vivo effect of TSA, however, has not been investigated in a transgenic lung cancer model. Previously, we generated transgenic mice with overexpression of Groucho-related-gene 1 (Grg1) and these mice all developed mucinous lung adenocarcinoma.

Short-term, low-dose cadmium exposure induces hyperpermeability in human renal glomerular endothelial cells.

The kidney is the principal organ targeted by exposure to cadmium (Cd), a well-known toxic metal. Even at a low level, Cd damages glomerular filtration. However, little is known about the effects of Cd on the glomerular endothelium, which performs the filtration function and directly interacts with Cd in blood plasma.

CCR5 facilitates endothelial progenitor cell recruitment and promotes the stabilization of atherosclerotic plaques in ApoE-/- mice.

Introduction: Unstable atherosclerotic plaques are prone to rupture, which leads to atherothrombosis. Endothelial progenitor cells (EPCs) are bone marrow-derived precursor cells that may repair vascular injury in atherosclerosis. Chemokine (C-C motif) receptor 5 (CCR5) promotes mobilization of EPCs.

Conditional and inducible transgene expression in endothelial and hematopoietic cells using Cre/ and tetracycline-off systems.

In the present study, the tetracycline-off and Cre/ systems were combined to gain temporal and spatial control of transgene expression. Mice were generated that carried three transgenes: Tie2-tTA, tet-O-Cre and either the ZEG or ZAP reporter. Tie2-tTA directs expression of tetracycline-controlled transactivator (tTA) in endothelial and hematopoietic cells under the control of the Tie2 promoter.

Postnatal Notch1 activation induces T‑cell malignancy in conditional and inducible mouse models.

The Notch1 signaling pathway is essential for hematopoietic development. However, the effects of postnatal activation of Notch1 signaling on hematopoietic system is not yet fully understood. We previously generated ZEG‑IC‑Notch1 transgenic mice that have a floxed β‑geo/stop signal between a CMV promoter and intracellular domain of Notch1 (IC‑Notch1).

Constitutively active Notch1 signaling promotes endothelial‑mesenchymal transition in a conditional transgenic mouse model.

Endothelial-mesenchymal transition (EndoMT) is a process in which endothelial cells lose their cell-type‑specific characteristics and gain a mesenchymal cell phenotype. The Notch signaling pathway is crucial in the regulation of EndoMT; however, its roles have not been fully studied in vivo. In a previous study, we reported the generation of transgenic mice with a floxed β-geo/stop signal between a CMV promoter and the constitutively active intracellular domain of Notch1 (IC-Notch1) linked with a human placental alkaline phosphatase (hPLAP) reporter (ZAP-IC-Notch1).

Constitutive notch signaling in adult transgenic mice inhibits bFGF-induced angiogenesis and blocks ovarian follicle development.

Notch signaling is important in angiogenesis during embryonic development. However, the embryonic lethal phenotypes of knock-out and transgenic mice have precluded studies of the role of Notch post-natally. To develop a mouse model that would bypass the embryonic lethal phenotype and investigate the possible role of Notch signaling in adult vessel growth, we developed transgenic mice with Cre-conditional expression of the constitutively active intracellular domain of Notch1 (IC-Notch1).

Zonadhesin is essential for species specificity of sperm adhesion to the egg zona pellucida.

Interaction of rapidly evolving molecules imparts species specificity to sperm-egg recognition in marine invertebrates, but it is unclear whether comparable interactions occur during fertilization in any vertebrate species. In mammals, the sperm acrosomal protein zonadhesin is a rapidly evolving molecule with species-specific binding activity for the egg zona pellucida (ZP). Here we show using null mice produced by targeted disruption of Zan that zonadhesin confers species specificity to sperm-ZP adhesion.

Genomic localization of the Z/EG transgene in the mouse genome.

The Z/EG transgenic mouse line, produced by Novak et al., displays tissue-specific EGFP expression after Cre-mediated recombination. The autofluorescence of EGFP allows the visualization of cells of interest displaying Cre recombination.

Ectopic notch activation in developing podocytes causes glomerulosclerosis.

Genetic evidence supports an early role for Notch signaling in the fate of podocytes during glomerular development. Decreased expression of Notch transcriptional targets in developing podocytes after the determination of cell fate suggests that constitutive Notch signaling may oppose podocyte differentiation. This study determined the effects of constitutive Notch signaling on podocyte differentiation by ectopically expressing Notch's intracellular domain (NOTCH-IC), the biologically active, intracellular product of proteolytic cleavage of the Notch receptor, in developing podocytes of transgenic mice.

ARS2 is a conserved eukaryotic gene essential for early mammalian development.

Determining the functions of novel genes implicated in cell survival is directly relevant to our understanding of mammalian development and carcinogenesis. ARS2 is an evolutionarily conserved gene that confers arsenite resistance on arsenite-sensitive Chinese hamster ovary cells. Little is known regarding the function of ARS2 in mammals.

Cre-conditional expression of constitutively active Notch1 in transgenic mice.

The Notch signaling pathway plays a critical role during mammalian development. To bypass embryonic lethality associated with constitutive Notch1 signaling, we created transgenic mice with a floxed beta-geo/stop signal between a cytomegalo virus promoter and the constitutively active intracellular domain of Notch1 (IC-Notch1). IC-Notch1 is activated upon introduction of Cre recombinase and it is coexpressed with an enhanced green fluorescent protein or human placental alkaline phosphatase reporter.

Reporter expression, induced by a growth hormone promoter-driven Cre recombinase (rGHp-Cre) transgene, questions the developmental relationship between somatotropes and lactotropes in the adult mouse pituitary gland.

This report describes the development and validation of the rGHp-Cre transgenic mouse that allows for selective Cre-mediated recombination of loxP-modified alleles in the GH-producing cells of the anterior pituitary. Initial screening of the rGHp-Cre parental line showed Cre mRNA was specifically expressed in the anterior pituitary gland of adult Cre+/- mice and cephalic extracts of e17 Cre+/- fetuses. Heterozygote rGHp-Cre transgenic mice were crossbred with Z/AP reporter mice to generate Cre+/-,Z/AP+/- offspring.

Grg1 acts as a lung-specific oncogene in a transgenic mouse model.

Groucho proteins are transcriptional corepressors that are recruited to gene regulatory regions by numerous transcription factors. Long isoforms, such as Grg1, have all the domains of the prototype Drosophila Groucho. Short Groucho proteins, such as Grg5, have only the amino-terminal Q and G/P domains.

Glypican-3 promotes the growth of hepatocellular carcinoma by stimulating canonical Wnt signaling.

Glypican-3 (GPC3) is a heparan sulfate proteoglycan that is bound to the cell membrane by a glycosyl-phosphatidylinositol anchor. GPC3 is expressed by most hepatocellular carcinomas but not by normal hepatocytes and benign liver lesions. We report here that GPC3 stimulates the in vitro and in vivo growth of hepatocellular carcinoma cells by increasing autocrine/paracrine canonical Wnt signaling.

Hepatic vascular tumors, angiectasis in multiple organs, and impaired spermatogenesis in mice with conditional inactivation of the VHL gene.

von Hippel-Lindau (VHL) disease is a multisystem inherited cancer syndrome characterized by the development of highly vascular tumors including hemangioblastomas of the retina and central nervous system, pheochromocytomas, and clear cell renal carcinoma, which result from somatic inactivation of the wild-type VHL allele in cells harboring a germ-line VHL mutation. Homozygous inactivation of the VHL gene in mice resulted in embryonic lethality. To produce a mouse model that closely mimics human VHL disease and avoids embryonic lethality, we used Cre/lox site-specific recombination technology.

Contrasting effects of VEGF gene disruption in embryonic stem cell-derived versus oncogene-induced tumors.

Previous gene targeting studies have implicated an indispensable role of vascular endothelial growth factor (VEGF) in tumor angiogenesis, particularly in tumors of embryonal or endocrine origin. In contrast, we report here that transformation of VEGF-deficient adult fibroblasts (MDF528) with ras or neu oncogenes gives rise to highly tumorigenic and angiogenic fibrosarcomas. These aggressive VEGF-null tumors (528ras, 528neu) originated from VEGF(-/-) embryonic stem cells, which themselves were tumorigenically deficient.

Genetic evidence that relative synaptic efficacy biases the outcome of synaptic competition.

Synaptic activity drives synaptic rearrangement in the vertebrate nervous system; indeed, this appears to be a main way in which experience shapes neural connectivity. One rearrangement that occurs in many parts of the nervous system during early postnatal life is a competitive process called 'synapse elimination'. At the neuromuscular junction, where synapse elimination has been analysed in detail, muscle fibres are initially innervated by multiple axons, then all but one are withdrawn and the 'winner' enlarges.

The post-natal heart contains a myocardial stem cell population.

The recent identification of stem cell pools in a variety of unexpected tissue sources has raised the possibility that a pluripotent stem cell population may reside in the myocardium and contribute to the post-natal growth of this tissue. Here, we demonstrate that the post-natal myocardium contains a resident verapamil-sensitive side population (SP), with stem cell-like activity. When growth of the post-natal heart was attenuated through over-expression of a dominant negative cardiac transcription factor (MEF2C), the resident SP cell population was subject to activation, followed by a consequent depletion.

Early restriction of peripheral and proximal cell lineages during formation of the lung.

To establish the timing of lineage restriction among endodermal derivatives, we developed a method to label permanently subsets of lung precursor cells at defined times during development by using Cre recombinase to activate floxed alkaline phosphatase or green fluorescent protein genes under control of doxycycline-dependent surfactant protein C promoter. Extensive or complete labeling of peripheral lung, thyroid, and thymic epithelia, but not trachea, bronchi, or gastrointestinal tract occurred when mice were exposed to doxycycline from embryonic day (E) 4.5 to E6.

Expression of Cre Recombinase in the developing mouse limb bud driven by a Prxl enhancer.

We have used a Prx1 limb enhancer to drive expression of Cre Recombinase in transgenic mice. This regulatory element leads to Cre expression throughout the early limb bud mesenchyme and in a subset of craniofacial mesenchyme. Crossing a murine line carrying this transgene to a reporter mouse harboring a floxed Cre-reporter cassette revealed that recombinase activity is first observed in the earliest limb bud at 9.