[The association between portal vein thrombosis and rebleeding after non-urgent endoscopic treatment of esophagogastric varices]

Objective: To investigate the association between portal vein thrombosis and rebleeding after non-urgent endoscopic treatment of esophagogastric varices. Methods: The cirrhotic patients with esophagogastric varices diagnosed in the People's Hospital of Zhengzhou University from January 2017 to March 2023 were retrospectively collected. The patients were divided into thrombotic group and non-thrombotic group according to the presence or absence of portal vein thrombosis. The failure rate of endoscopic treatment and rebleeding rate in different periods were compared between the two groups. Receiver operating characteristic (ROC) curve was used to select the best cutoff value of gastric varicose diameter that affected total rebleeding during follow-up in both groups. The influencing factors of rebleeding within 12 and 36 months in both groups were analyzed, and the influencing factors of rebleeding within 36 months in thrombus group were further analyzed. Results: A total of 106 patients were enrolled, including 53 patients in the thrombotic group [male 37, female 16, aged 18-78 (54±13) years] and 53 patients in the non-thrombotic group [male 37, female 16, aged 27-83 (55±12) years]. The follow-up time of the two groups were (20±15) and (25±15) months, respectively. The total rebleeding rate in the thrombotic group was higher than that in the non-thrombotic group [30.2% (16/53) vs 13.2% (7/53), P˂0.05]. The rebleeding rates within 6, 12, 24 and 36 months in the thrombotic group were higher than those in the non-thrombotic group [18.9% (10/53) vs 5.7% (3/53), 18.9% (10/53) vs 5.7% (3/53), 28.3% (15/53) vs 9.4% (5/53), 30.2% (16/53) vs 11.3% (6/53), all P˂0.05]. The best cut-off value of the diameter of gastric varices that affects the total rebleeding in the two groups was 10.4 mm (10 mm was selected as the best cut-off value for the convenience of practical clinical application). Hemoglobin ˂ 85 g/L (HR=0.202, 95%CI: 0.043-0.953, P=0.043), 10 mm ˂ the diameter of GV ≤ 15 mm (HR=5.321, 95%CI: 1.161-24.390, P=0.031) and endoscopic variceal ligation combined with endoscopic tissue adhesive injection (EVL+ETAI) (HR=7.172, 95%CI: 1.910-26.930, P=0.004) were the risk factors for the first gastroesophageal variceal rebleeding within 12 months after non-urgent endoscopic treatment. EVL+ETAI (HR=3.811, 95%CI: 1.441-10.084, P=0.007) and portal vein thrombosis (HR=4.026, 95%CI: 1.483-10.932, P=0.006) were the risk factors for the first gastroesophageal variceal rebleeding within 36 months after non-urgent endoscopic treatment. The study found that, 10 mm ˂ the diameter of GV ≤ 15 mm (HR=7.503, 95%CI: 1.568-35.890, P=0.012) was the risk factor for rebleeding within 36 months in the thrombotic group. Conclusion: Portal vein thrombosis is a risk factor for rebleeding after non-urgent endoscopic treatment of esophagogastric varices.

Reduced graphene oxides: the thinnest and most lightweight materials with highly efficient microwave attenuation performances of the carbon world

In this work, reduced graphene oxide (r-GO) and graphite nanosheet (GN) were obtained via the chemical approach. Furthermore, r-GO composites and GN composites were prepared with a paraffin wax host. r-GO composites show high dielectric properties and electromagnetic interference shielding efficiency (EMI SE). Compared with the GN composites, the loss tangent and EMI SE of the r-GO composites with the same mass ratio are enhanced ∼5 to 10 times and ∼3 to 10 times, respectively. The enhanced attenuation capacity arises from higher specific surface area, clustered defects and residual bonds of the r-GOs, which increase the polarization loss, scattering and conductivity of the composite. Moreover, the higher conductivity of r-GO composites leads to higher EMI SE compared with that of GN composites. These results suggest that r-GOs are highly promising fillers for microwave attenuation in the carbon family and that r-GO composites are high-performance EMI shielding materials with application anticipated to many fields.

Development and regeneration of Sox2+ endoderm progenitors are regulated by a Hdac1/2-Bmp4/Rb1 regulatory pathway

The mechanisms that govern the maintenance and differentiation of tissue-specific progenitors in development and tissue regeneration are poorly understood. We show that development of Sox2+ progenitors in the lung endoderm is regulated by histone deacetylases 1 and 2 (Hdac1/2). Hdac1/2 deficiency leads to a loss of Sox2 expression and a block in proximal airway development. This is mediated in part by derepression of Bmp4 and the tumor suppressor Rb1, which are direct transcriptional targets of Hdac1/2. In contrast to development, postnatal loss of Hdac1/2 in airway epithelium does not affect the expression of Sox2 or Bmp4. However, postnatal loss of Hdac1/2 leads to increased expression of the cell-cycle regulators Rb1, p21/Cdkn1a, and p16/Ink4a, resulting in a loss of cell-cycle progression and defective regeneration of Sox2+ lung epithelium. Thus, Hdac1/2 have both common and unique targets that differentially regulate tissue-specific progenitor activity during development and regeneration.

Formation of nanostructure and nano-hardness characterization on the meso-scale workpiece by a novel laser indirect shock forming method

The meso-scale workpiece with greatly enhanced mechanical properties is potential to be widely used in the electronics productions and micro-electro mechanical systems. In this study, it demonstrates that the meso-scale cup-shape workpiece with good geometry can be obtained by a novel laser indirect shock forming method. After the forming process, the mechanical properties and microstructures of the formed workpiece were characterized. By transmission electron microscope observation, it was found that a mixed refined microstructure consisting of nano-scale twins embedded in nano-sized grains was produced at the center of the formed sample. Formation of these nanograins could be mainly attributed to two mechanisms: twin-twin intersections and twin∕matrix lamellae fragmentation. By nanoindentation tests, it reveals that the hardness of the sample has increased greatly after laser shock forming and the hardness increases with the laser energy. The elevated hardness originates from a considerable number of nano-scale twins and nanograins, which possess a pretty high strength due to the significant effects of grain boundary strengthening and twin boundary strengthening.

The bone morphogenic protein antagonist gremlin regulates proximal-distal patterning of the lung

The proximal-distal patterning of lung epithelium involves a complex series of signaling and transcriptional events resulting in the programmed differentiation of highly specialized cells for gas exchange and surfactant protein expression essential for postnatal lung function. The BMP signaling pathway has been shown to regulate cellular differentiation in the lung as well as other tissues. In this report, we show that the can family of related BMP antagonists, including gremlin, cer-1, PRDC, and Dan are expressed in the lung during embryonic development with gremlin expression observed in the proximal airway epithelium. The role of gremlin in lung development was explored by overexpressing it in the distal lung epithelium of transgenic mice using the human SP-C promoter. SP-C/gremlin transgenic mice exhibited a disruption of the proximal-distal patterning found in the airways of the mammalian lung. Expanded expression of the proximal epithelial cell markers CC10 and HFH-4 (Foxj1) was observed in the distal regions of transgenic lungs. Furthermore, smooth muscle alpha-actin expression was observed surrounding the distal airways of SP-C/gremlin mice, indicating a proximalization of distal lung tubules. These data suggest that gremlin plays an important role in lung morphogenesis by regulating the proximal-distal patterning of the lung during development.

Mice overexpressing genes from the 22q11 region deleted in velo-cardio-facial syndrome/DiGeorge syndrome have middle and inner ear defects

Velo-cardio-facial syndrome/DiGeorge syndrome (VCFS/DGS) is a congenital anomaly disorder associated with hemizygous 22q11 deletions. We previously showed that bacterial artificial chromosome (BAC) transgenic mice overexpressing four transgenes, PNUTL1, (CDCrel-1), GP1B beta, TBX1 and WDR14, had reduced viability, cardiovascular malformations and thymus gland hypoplasia. Since these are hallmark features of VCFS/DGS, we analyzed the mice for additional anomalies. We found that the mice have important defects in the middle and inner ear that are directly relevant to the disorder. The most striking defect was the presence of chronic otitis media, a common finding in VCFS/DGS patients. In addition, the mice had a hyperactive circling behavior and sensorineural hearing loss. This was associated with middle and inner ear malformations, analogous to Mondini dysplasia in humans reported to occur in VCFS/DGS patients. We propose that overexpression of one or more of the transgenes is responsible for the etiology of the ear defects in the mice. Based upon its pattern of expression in the ear and functional studies of the gene, TbX1 likely plays a central role. Haploinsufficiency of TBX1 may be responsible for ear disorders in VCFS/DGS patients.

Characterization of Wnt gene expression in developing and postnatal hair follicles and identification of Wnt5a as a target of Sonic hedgehog in hair follicle morphogenesis

Mutations in WNT effector genes perturb hair follicle morphogenesis, suggesting key roles for WNT proteins in this process. We show that expression of Wnts 10b and 10a is upregulated in placodes at the onset of follicle morphogenesis and in postnatal hair follicles beginning a new cycle of hair growth. The expression of additional Wnt genes is observed in follicles at later stages of differentiation. Among these, we find that Wnt5a is expressed in the developing dermal condensate of wild type but not Sonic hedgehog (Shh)-null embryos, indicating that Wnt5a is a target of SHH in hair follicle morphogenesis. These results identify candidates for several key follicular signals and suggest that WNT and SHH signaling pathways interact to regulate hair follicle morphogenesis.

Targeted disruption of semaphorin 3C leads to persistent truncus arteriosus and aortic arch interruption

Semaphorin 3C is a secreted member of the semaphorin gene family. To investigate its function in vivo, we have disrupted the semaphorin 3Clocus in mice by targeted mutagenesis. semaphorin 3C mutant mice die within hours after birth from congenital cardiovascular defects consisting of interruption of the aortic arch and improper septation of the cardiac outflow tract. This phenotype is similar to that reported following ablation of the cardiac neural crest in chick embryos and resembles congenital heart defects seen in humans. Semaphorin 3C is expressed in the cardiac outflow tract as neural crest cells migrate into it. Their entry is disrupted in semaphorin 3C mutant mice. These data suggest that semaphorin 3C promotes crest cell migration into the proximal cardiac outflow tract.

PlexinA2 and semaphorin signaling during cardiac neural crest development

Classic studies using avian model systems have demonstrated that cardiac neural crest cells are required for proper development of the cardiovascular system. Environmental influences that perturb neural crest development cause congenital heart defects in laboratory animals and in man. However, little progress has been made in determining molecular programs specifically regulating cardiac neural crest migration and function. Only recently have complex transgenic tools become available that confirm the presence of cardiac neural crest cells in the mammalian heart. These studies have relied upon the use of transgenic mouse lines and fate-mapping studies using Cre recombinase and neural crest-specific promoters. In this study, we use these techniques to demonstrate that PlexinA2 is expressed by migrating and postmigratory cardiac neural crest cells in the mouse. Plexins function as co-receptors for semaphorin signaling molecules and mediate axon pathfinding in the central nervous system. We demonstrate that PlexinA2-expressing cardiac neural crest cells are patterned abnormally in several mutant mouse lines with congenital heart disease including those lacking the secreted signaling molecule Semaphorin 3C. These data suggest a parallel between the function of semaphorin signaling in the central nervous system and in the patterning of cardiac neural crest in the periphery.

Characterization of a New Subfamily of Winged-helix/Forkhead (Fox) Genes That Are Expressed in the Lung and Act as Transcriptional Repressors

Epithelial gene expression in the lung is thought to be regulated by the coordinate activity of several different families of transcription factors including the Fox family of winged-helix/forkhead DNA-binding proteins. In this report, we have identified and characterized two members of this Fox gene family, Foxp1 and Foxp2, and show that they comprise a new subfamily of Fox genes expressed in the lung. Foxp1 and Foxp2 are expressed at high levels in the lung as early as E12.5 of mouse development with Foxp2 expression restricted to the airway epithelium. In addition, Foxp1 and Foxp2 are expressed at lower levels in neural, intestinal, and cardiovascular tissues during development. Upon differentiation of the airway epithelium along the proximal-distal axis, Foxp2 expression becomes restricted to the distal alveolar epithelium whereas Foxp1 expression is observed in the distal epithelium and mesenchyme. Foxp1 and Foxp2 can regulate epithelial lung gene transcription as was demonstrated by their ability to dramatically repress the mouse CC10 promoter and, to a lesser extent, the human surfactant protein C promoter. In addition, GAL4 fusion proteins encoding subdomains of Foxp1 and Foxp2 demonstrate that an independent and homologous transcriptional repression domain lies within the N-terminal end of the proteins. Together, these studies suggest that Foxp1 and Foxp2 are important regulators of lung epithelial gene transcription.

TBX1 is responsible for cardiovascular defects in velo-cardio-facial/DiGeorge syndrome

Velo-cardio-facial syndrome (VCFS)/DiGeorge syndrome (DGS) is a human disorder characterized by a number of phenotypic features including cardiovascular defects. Most VCFS/DGS patients are hemizygous for a 1.5-3.0 Mb region of 22q11. To investigate the etiology of this disorder, we used a cre-loxP strategy to generate mice that are hemizygous for a 1.5 Mb deletion corresponding to that on 22q11. These mice exhibit significant perinatal lethality and have conotruncal and parathyroid defects. The conotruncal defects can be partially rescued by a human BAC containing the TBX1 gene. Mice heterozygous for a null mutation in Tbx1 develop conotruncal defects. These results together with the expression patterns of Tbx1 suggest a major role for this gene in the molecular etiology of VCFS/DGS.

Analysis of SM22alpha-deficient mice reveals unanticipated insights into smooth muscle cell differentiation and function

SM22alpha is a 22-kDa smooth muscle cell (SMC) lineage-restricted protein that physically associates with cytoskeletal actin filament bundles in contractile SMCs. To examine the function of SM22alpha, gene targeting was used to generate SM22alpha-deficient (SM22(-/-LacZ)) mice. The gene targeting strategy employed resulted in insertion of the bacterial lacZ reporter gene at the SM22alpha initiation codon, permitting precise analysis of the temporal and spatial pattern of SM22alpha transcriptional activation in the developing mouse. Northern and Western blot analyses confirmed that the gene targeting strategy resulted in a null mutation. Histological analysis of SM22(+/-LacZ) embryos revealed detectable beta-galactosidase activity in the unturned embryonic day 8.0 embryo in the layer of cells surrounding the paired dorsal aortae concomitant with its expression in the primitive heart tube, cephalic mesenchyme, and yolk sac vasculature. Subsequently, during postnatal development, beta-galactosidase activity was observed exclusively in arterial, venous, and visceral SMCs. SM22alpha-deficient mice are viable and fertile. Their blood pressure and heart rate do not differ significantly from their control SM22alpha(+/-) and SM22alpha(+/+) littermates. The vasculature and SMC-containing tissues of SM22alpha-deficient mice develop normally and appear to be histologically and ultrastructurally similar to those of their control littermates. Taken together, these data demonstrate that SM22alpha is not required for basal homeostatic functions mediated by vascular and visceral SMCs in the developing mouse. These data also suggest that signaling pathways that regulate SMC specification and differentiation from local mesenchyme are activated earlier in the angiogenic program than previously recognized.

Pax3 is required for enteric ganglia formation and functions with Sox10 to modulate expression of c-ret

Hirschsprung disease and Waardenburg syndrome are human genetic diseases characterized by distinct neural crest defects. Patients with Hirschsprung disease suffer from gastrointestinal motility disorders, whereas Waardenburg syndrome consists of defective melanocyte function, deafness, and craniofacial abnormalities. Mutations responsible for Hirschsprung disease and Waardenburg syndrome have been identified, and some patients have been described with characteristics of both disorders. Here, we demonstrate that PAX3, which is often mutated in Waardenburg syndrome, is required for normal enteric ganglia formation. Pax3 can bind to and activate expression of the c-RET gene, which is often mutated in Hirschsprung disease. Pax3 functions with Sox10 to activate transcription of c-RET, and SOX10 mutations result in Waardenburg-Hirschsprung syndrome. Thus, Pax3, Sox10, and c-Ret are components of a neural crest development pathway, and interruption of this pathway at various stages results in neural crest-related human genetic syndromes.

Cloning and expression analysis of murine lupin, a member of a novel gene family that is conserved through evolution and associated with Lupus inclusions

We describe here the first full-length sequence of a member of a novel gene family encoding a protein in the mouse that we call Lupin. Lupin is homologous to a human protein previously called p36, which was purified from alpha-interferon-treated cells that formed lupus inclusions. Lupus inclusions are dense intracellular deposits found in endothelial cells and lymphocytes of patients with systemic lupus erythematosis and AIDS. Proteins closely related to Lupin exist in evolutionarily divergent species including Caenorhabditis elegans, Drosophila and zebrafish. At least one other lupin-related gene is expressed in the mouse and in man. Lupin is expressed in mouse embryos and adults, notably in liver, spleen, central nervous system, multiple epithelia and all types of muscle. In skeletal muscle, expression analysis suggests that Lupin associates with the contractile apparatus.

The gene encoding the mitogen-responsive phosphoprotein Dab2 is differentially regulated by GATA-6 and GATA-4 in the visceral endoderm

Gene targeting studies have demonstrated that the zinc finger transcription factor GATA-6 lies upstream in a transcriptional cascade that controls differentiation of the visceral endoderm. To understand the function of GATA-6 in the visceral endoderm and to identify genes regulated by GATA-6 in this tissue, subtractive hybridization was performed using template cDNAs derived from differentiated wild-type embryonic stem (ES) cells and GATA-6(-/-) ES cells, respectively. These analyses revealed that the gene encoding Dab2, a mitogen-responsive phosphoprotein, is differentially expressed in wild-type and GATA-6-deficient ES cells. Consistent with these findings, Dab2 is expressed in the visceral endoderm of wild-type embryos but not in the visceral endoderm of GATA-6-deficient embryos. Cotransfection experiments demonstrate that the human Dab2 promoter can be transactivated by forced expression of GATA-6 in NIH-3T3 cells. In contrast, forced expression of GATA-4 does not transactivate the human Dab2 promoter and Dab2 is expressed in the visceral endoderm of GATA-4 null embryos. Surprisingly, the specificity of GATA-6-induced transactivation of the Dab2 promoter is not mediated through its zinc finger DNA-binding domain. Taken together, these data demonstrate that the mitogen-responsive phosphoprotein Dab2 is a downstream target of GATA-6 in the visceral endoderm. Moreover, these data demonstrate that molecular mechanisms have evolved that direct, and distinguish, the functional specificity of GATA family members when they are developmentally coexpressed.

Migration of cardiac neural crest cells in Splotch embryos

Pax3 encodes a transcription factor expressed during mid-gestation in the region of the dorsal neural tube that gives rise to migrating neural crest populations. In the absence of Pax3, both humans and mice develop with neural crest defects. Homozygous Splotch embryos that lack Pax3 die by embryonic day 13.5 with cardiac defects that resemble those induced by neural crest ablation in chick models. This has led to the hypothesis that Pax3 is required for cardiac neural crest migration. However, cardiac derivatives of Pax3-expressing precursor cells have not been previously defined, and Pax3-expressing cells within the heart have not been well demonstrated. Hence, the precise role of Pax3 during cardiac development remains unclear. Here, we use a Cre-lox method to fate map Pax3-expressing neural crest precursors to the cardiac outflow tract. We show that although Pax3 itself is extinguished prior to neural crest populating the heart, derivatives of these precursors contribute to the aorticopulmonary septum. We further show that neural crest cells are found in the outflow tract of Splotch embryos, albeit in reduced numbers. This indicates that contrary to prior reports, Pax3 is not required for cardiac neural crest migration. Using a neural tube explant culture assay, we demonstrate that neural crest cells from Splotch embryos show normal rates of proliferation but altered migratory characteristics. These studies suggest that Pax3 is required for fine tuning the migratory behavior of the cardiac neural crest cells while it is not essential for neural crest migration.

Transgenic rescue of congenital heart disease and spina bifida in Splotch mice

Pax3-deficient Splotch mice display neural tube defects and an array of neural crest related abnormalities including defects in the cardiac outflow tract, dorsal root ganglia and pigmentation. Pax3 is expressed in neural crest cells that emerge from the dorsal neural tube. Pax3 is also expressed in the somites, through which neural crest cells migrate, where it is required for hypaxial muscle development. Homozygous mutant Splotch embryos die by embryonic day 14. We have utilized the proximal 1.6 kb Pax3 promoter and upstream regulatory elements to engineer transgenic mice reproducing endogenous Pax3 expression in neural tube and neural crest, but not the somite. Over expression of Pax3 in these tissues reveals no discernible phenotype. Breeding of transgenic mice onto a Splotch background demonstrates that neural tube and neural crest expression of Pax3 is sufficient to rescue neural tube closure, cardiac development and other neural crest related defects. Transgenic Splotch mice survive until birth at which time they succumb to respiratory failure secondary to absence of a muscular diaphragm. Limb muscles are also absent. These results indicate that regulatory elements sufficient for functional expression of Pax3 required for cardiac development and neural tube closure are contained within the region 1.6 kb upstream of the Pax3 transcriptional start site. In addition, the single Pax3 isoform used for this transgene is sufficient to execute these developmental processes. Although the extracellular matrix and the environment of the somites through which neural crest migrates is known to influence neural crest behavior, our results indicate that Pax3-deficient somites are capable of supporting proper neural crest migration and function suggesting a cell autonomous role for Pax3 in neural crest.

Adeno-associated virus as a vector for liver-directed gene therapy

Factors relevant to the successful application of adeno-associated virus (AAV) vectors for liver-directed gene therapy were evaluated. Vectors with different promoters driving expression of human alpha-1-antitrypsin (alpha-1AT) were injected into the portal circulation of immunodeficient mice. alpha-1AT expression was stable but dependent on the promoter. Southern analysis of liver DNA revealed approximately 0.1 to 2.0 provirus copies/diploid genome in presumed head-to-tail concatamers. In situ hybridization and immunohistochemical analysis revealed expression in approximately 5% of hepatocytes clustered in the pericentral region. These results support the use of AAV as a vector for diseases treatable by targeting of hepatocytes.

GATA6 regulates HNF4 and is required for differentiation of visceral endoderm in the mouse embryo

GATA6 belongs to a family of zinc finger transcription factors that play important roles in transducing nuclear events that regulate cellular differentiation and embryonic morphogenesis in vertebrate species. To examine the function of GATA6 during embryonic development, gene targeting was used to generate GATA6-deficient (GATA6(-/-)) ES cells and mice harboring a null mutation in GATA6. Differentiated embryoid bodies derived from GATA6(-/-) ES cells lack a covering layer of visceral endoderm and severely attenuate, or fail to express, genes encoding early and late endodermal markers, including HNF4, GATA4, alpha-fetoprotein (AFP), and HNF3beta. Homozygous GATA6(-/-) mice died between embryonic day (E) 6.5 and E7. 5 and exhibited a specific defect in endoderm differentiation including severely down-regulated expression of GATA4 and absence of HNF4 gene expression. Moreover, widespread programmed cell death was observed within the embryonic ectoderm of GATA6-deficient embryos, a finding also observed in HNF4-deficient embryos. Consistent with these data, forced expression of GATA6 activated the HNF4 promoter in nonendodermal cells. Finally, to examine the function of GATA6 during later embryonic development, GATA6(-/-)-C57BL/6 chimeric mice were generated. lacZ-tagged GATA6(-/-) ES cells contributed to all embryonic tissues with the exception of the endodermally derived bronchial epithelium. Taken together, these data suggest a model in which GATA6 lies upstream of HNF4 in a transcriptional cascade that regulates differentiation of the visceral endoderm. In addition, these data demonstrate that GATA6 is required for establishment of the endodermally derived bronchial epithelium.

Establishment and characterization of a megakaryoblast cell line with amplification of MLL

A new cell line with megakaryoblastic features, designated UoC-M1, was established from the malignant cells of a 68-year-old patient with acute myeloid leukemia. The patient's leukemic cells reacted with alpha-naphthyl acetate esterase and acid phosphatase and expressed CD7, CD24, CD34, CD38, CD45, HLA-DR and CD61. Cytogenetic analysis of the patient's malignant cells (and of the UoC-M1 cells) showed a human, male hypodiploid karyotype with many chromosome rearrangements and marker chromosomes. Spectral karyotyping (SKY) analysis complemented the G-banded karyotyping and clarified several chromosomal translocations and identified the marker chromosomes. Fluorescence in situ hybridization (FISH) and SKY analysis demonstrated that one marker chromosome contained three segments of chromosome 9 interspersed with three segments of chromosome 11, as well as a portion of chromosome 19. FISH analysis with a probe for MLL revealed that the UoC-M1 cells contained four copies of the MLL gene. Southern blot analysis determined that the MLL gene had a germline profile while Northern and Western analyses showed that the MLL mRNAs and protein were of the appropriate sizes. This is the first report of amplification of the MLL gene which may be an additional mechanism of leukemogenesis or disease progression.

Expression pattern of the Ets-related transcription factor Elf-1

Members of the Ets family of winged helix-loop-helix transcription factors play important roles in the development and function of multiple mammalian cell lineages. Elf-1 is an Ets-related transcription factor that is expressed at high levels in T cells and is known to regulate the expression of several T cell genes, including the granulocyte-macrophage colony stimulating factor (GM-CSF) gene, the interleukin-2 receptor alpha subunit (IL-2Ralpha) gene, and the CD4 gene. In the studies described in this report, we have characterized the pattern of expression of Elf-1 in the developing mouse embryo and in adult mouse tissues as well as in multiple immortalized human and murine cell lines. Elf-1 is expressed at high levels throughout thymocyte development, with equivalent levels of Elf-1 expression seen in all subsets of maturing thymocytes and T cells. Somewhat surprisingly, however, Elf-1 is also expressed at high levels in epithelial cells lining the oral cavity, the lung, the CNS, and the gastrointestinal and urinary tracts as well as in the skin of the developing mouse embryo and at lower levels in the adult mouse testis and liver. Western blot analyses of a large number of immortalized cell lines demonstrated high-level Elf-1 expression in T and B lymphocyte and macrophage cell lines as well as in two prostate carcinoma cell lines. Low-level expression was observed in fibroblasts, embryonic stem cells, and myoblasts. Taken together, our data suggest that in addition to its role in regulating T cell development and function, Elf-1 may regulate gene expression in the B cell and myelomonocytic lineages, as well as in multiple epithelial cell types during murine embryonic development.

Expression of ARNT, ARNT2, HIF1 alpha, HIF2 alpha and Ah receptor mRNAs in the developing mouse

The basic helix-loop-helix-PAS (bHLH-PAS) protein ARNT is a dimeric partner of the Ah receptor (AHR) and hypoxia inducible factor 1 alpha(HIF1 alpha). These dimers mediate biological responses to xenobiotic exposure and low oxygen tension. The recent cloning of ARNT and HIF1(homologues (ARNT2 and HIF2 alpha) indicates that at least six distinct bHLH-PAS heterodimeric combinations can occur in response to a number of environmental stimuli. In an effort to understand the biological relevance of this combinatorial complexity, we characterized their relative expression at a number of developmental time points by parallel in situ hybridization of adjacent tissue sections. Our results reveal that in general there is limited redundancy in the expression of these six transcription factors and that each of these bHLH-PAS members displays a unique pattern of developmental expression emerging as early as embryonic day 9.5.

The LKLF transcription factor is required for normal tunica media formation and blood vessel stabilization during murine embryogenesis

The transcriptional programs that regulate blood vessel formation are largely unknown. In this paper, we examine the role of the zinc finger transcription factor LKLF in murine blood vessel morphogenesis and homeostasis. By in situ hybridization and immunohistochemistry, we show that LKLF is expressed as early as embryonic day 9.5 (E9.5) in vascular endothelial cells throughout the developing mouse embryo. To better understand the function of LKLF, we used homologous recombination in embryonic stem (ES) cells to generate LKLF-deficient (LKLF-/-) mice. Both angiogenesis and vasculogenesis were normal in the LKLF-/- mice. However, LKLF-/- embryos died between E12.5 and E14.5 from severe intra-embryonic and intra-amniotic hemorrhaging. This bleeding disorder was associated with specific defects in blood vessel morphology. Umbilical veins and arteries in the LKLF-/- embryos displayed an abnormally thin tunica media and aneurysmal dilatation before rupturing into the amniotic cavity. Similarly, vascular smooth muscle cells in the aortae from the LKLF-/- animals displayed a cuboidal morphology and failed to organize into a compact tunica media. Consistent with these findings, electron microscopic analyses demonstrated endothelial cell necrosis, significant reductions in the number of vessel-wall pericytes and differentiating smooth muscle cells, and decreased deposition of extracellular matrix in the LKLF-/- vessels. Despite these defects, in situ hybridization demonstrated normal expression of platelet-derived growth factor B, Tie1, Tie2, transforming growth factor beta, and heparin-binding epidermal growth factor in the vasculature of the LKLF-/- embryos. Therefore, LKLF defines a novel transcriptional pathway in which endothelial cells regulate the assembly of the vascular tunica media and concomitant vessel wall stabilization during mammalian embryogenesis.

GATA4 transcription factor is required for ventral morphogenesis and heart tube formation

Previous studies have suggested that the GATA4 transcription factor plays an important role in regulating mammalian cardiac development. In the studies described in this report we have used gene targeting to produce GATA4-deficient mice. Homozygous GATA4-deficient (GATA4-/-) mice died between 8.5 and 10.5 days post coitum (dpc). GATA4-/- embryos displayed severe defects in both rostral-to-caudal and lateral-to-ventral folding, which were reflected in a generalized disruption of the ventral body pattern. This resulted in the defective formation of an organized foregut and anterior intestinal pore, the failure to close both the amniotic cavity and yolk sac, and the uniform lack of a ventral pericardial cavity and heart tube. Analysis of cardiac development in the GATA4-/- mice demonstrated that these embryos developed splanchnic mesoderm, which differentiated into primitive cardiac myocytes that expressed contractile proteins. However, consistent with the observed defect in ventral morphogenesis, these GATA4-/- procardiomyocytes failed to migrate to the ventral midline to form a linear heart tube and instead formed aberrant cardiac structures in the anterior and dorsolateral regions of the embryo. The defect in ventral migration of the GATA4-/- procardiomyocytes was not cell intrinsic because GATA4-/- cardiac myocytes and endocardial cells populated the hearts of GATA4-/- -C57BL/6 chimeric mice. Taken together, these results demonstrated that GATA4 is not essential for the specification of the cardiac cell lineages. However, they define a critical role for GATA4 in regulating the rostral-to-caudal and lateral-to-ventral folding of the embryo that is needed for normal cardiac morphogenesis.

A serum response factor-dependent transcriptional regulatory program identifies distinct smooth muscle cell sublineages

The SM22alpha promoter has been used as a model system to define the molecular mechanisms that regulate smooth muscle cell (SMC) specific gene expression during mammalian development. The SM22alpha gene is expressed exclusively in vascular and visceral SMCs during postnatal development and is transiently expressed in the heart and somites during embryogenesis. Analysis of the SM22alpha promoter in transgenic mice revealed that 280 bp of 5' flanking sequence is sufficient to restrict expression of the lacZ reporter gene to arterial SMCs and the myotomal component of the somites. DNase I footprint and electrophoretic mobility shift analyses revealed that the SM22alpha promoter contains six nuclear protein binding sites (designated smooth muscle elements [SMEs] -1 to -6, respectively), two of which bind serum response factor (SRF) (SME-1 and SME-4). Mutational analyses demonstrated that a two-nucleotide substitution that selectively eliminates SRF binding to SME-4 decreases SM22alpha promoter activity in arterial SMCs by approximately 90%. Moreover, mutations that abolish binding of SRF to SME-1 and SME-4 or mutations that eliminate each SME-3 binding activity totally abolished SM22alpha promoter activity in the arterial SMCs and somites of transgenic mice. Finally, we have shown that a multimerized copy of SME-4 (bp -190 to -110) when linked to the minimal SM22alpha promoter (bp -90 to +41) is necessary and sufficient to direct high-level transcription in an SMC lineage-restricted fashion. Taken together, these data demonstrate that distinct transcriptional regulatory programs control SM22alpha gene expression in arterial versus visceral SMCs. Moreover, these data are consistent with a model in which combinatorial interactions between SRF and other transcription factors that bind to SME-4 (and that bind directly to SRF) activate transcription of the SM22alpha gene in arterial SMCs.

GATA-5: a transcriptional activator expressed in a novel temporally and spatially-restricted pattern during embryonic development

Members of the GATA family of zinc finger transcription factors regulate critical steps of cellular differentiation during vertebrate development. In the studies described in this report, we have isolated and functionally characterized the murine GATA-5 cDNA and protein and defined the temporal and spatial pattern of GATA-5 gene expression during mammalian development. The amino terminus of the mouse GATA-5 protein shares high level amino acid sequence identity with the murine GATA-4 and -6 proteins, but not with other members of the GATA family. GATA-5 binds to the functionally important CEF-1 nuclear protein binding site in the cardiac-specific slow/cardiac troponin C (cTnC) transcriptional enhancer and overexpression of GATA-5 transactivates the cTnC enhancer in noncardiac muscle cell lines. During embryonic and postnatal development, the pattern of GATA-5 gene expression differs significantly from that of other GATA family members. In the primitive streak embryo, GATA-5 mRNA is detectable in the precardiac mesoderm. Within the embryonic heart, the GATA-5 gene is expressed within the atrial and ventricular chambers (ED 9.5), becomes restricted to the atrial endocardium (ED 12.5), and is subsequently not expressed in the heart during late fetal and postnatal development. Moreover, coincident with the earliest steps in lung development, only the GATA-5 gene is expressed within the pulmonary mesenchyme. Finally, the GATA-5 gene is expressed in tissue-restricted subsets of smooth muscle cells (SMCs), including bronchial SMCs and SMCs in the bladder wall. These data are consistent with a model in which GATA-5 performs a unique temporally and spatially restricted function in the embryonic heart and lung. Moreover, these data suggest that GATA-5 may play an important role in the transcriptional program(s) that underlies smooth muscle cell diversity.

GATA-6: a zinc finger transcription factor that is expressed in multiple cell lineages derived from lateral mesoderm

Members of the GATA family of zinc finger transcription factors play important roles in the development of several mesodermally derived cell lineages. In the studies described in this report, we have isolated and functionally characterized the murine GATA-6 cDNA and protein and defined the temporal and spatial patterns of GATA-6 gene expression during mammalian development. The GATA-6 and -4 proteins share high-level amino acid sequence identity over a proline-rich region at the amino terminus of the protein that is not conserved in other GATA family members. GATA-6 binds to a functionally important nuclear protein binding site within the cardiac-specific cardiac troponin C (cTnC) transcriptional enhancer. Moreover, the cTnC promoter enhancer can be transactivated by overexpression of GATA-6 in noncardiac muscle cells. During early murine embryonic development, the patterns of GATA-6 and -4 gene expression are similar, with expression of GATA-6 restricted to the precardiac mesoderm, the embryonic heart tube, and the primitive gut. However, coincident with the onset of vasculogenesis and development of the respiratory and urogenital tracts, only the GATA-6 gene is expressed in arterial smooth muscle cells, the developing bronchi, and the urogenital ridge and bladder. These data are consistent with a model in which GATA-6 functions in concert with GATA-4 to direct tissue-specific gene expression during formation of the mammalian heart and gastrointestinal tract, but performs a unique function in programming lineage-restricted gene expression in the arterial system, the bladder, and the embryonic lung.

The Ets protein Spi-B is expressed exclusively in B cells and T cells during development

Spi-B and PU.1 are hematopoietic-specific transcription factors that constitute a subfamily of the Ets family of DNA-binding proteins. Here we show that contrary to previous reports, PU.1 and Spi-B have very different expression patterns. PU.1 is expressed at high levels in B cells, mast cells, megakaryocytes, macrophages, neutrophils, and immature erythroid cells and at lower levels in mature erythrocytes. PU.1 is completely absent from peripheral T cells and most T cell lines based on sensitive RT-PCR assays. In contrast, Spi-B is expressed exclusively in lymphoid cells and can be detected in early fetal thymus and spleen. In situ hybridizations of adult murine tissues demonstrate Spi-B mRNA in the medulla of the thymus, the white pulp of the spleen, and the germinal centers of lymph nodes. Spi-B expression is very abundant in B cells and both Spi-B mRNA and protein are detected in some T cells. In situ hybridization and Northern blot analysis suggest that Spi-B gene expression increases during B cell maturation and decreases during T cell maturation. Gel-retardation experiments show that Spi-B can bind to all putative PU.1 binding sites, but do not reveal any preferred Spi-B binding site. Finally, both PU.1 and Spi-B function as transcriptional activators of the immunoglobulin light-chain enhancer E lambda 2.4 when coexpressed with Pip (PU.1-interaction partner) in NIH-3T3 cells. Taken together, these data suggest that differences in patterns of expression between Spi-B and PU.1 distinguish the function of each protein during development of the immune system.

Adenovirus-mediated over-expression of the cyclin/cyclin-dependent kinase inhibitor, p21 inhibits vascular smooth muscle cell proliferation and neointima formation in the rat carotid artery model of balloon angioplasty

Vascular smooth muscle cell (VSMC) proliferation after arterial injury is important in the pathogenesis of a number of vascular proliferative disorders, including atherosclerosis and restenosis after balloon angioplasty. Thus, a better understanding of the molecular mechanisms underlying VSMC proliferation in response to arterial injury would have important therapeutic implications for patients with atherosclerotic vascular disease. The p21 protein is a negative regulator of mammalian cell cycle progression that functions both by inhibiting cyclin dependent kinases (CDKs) required for the initiation of S phase, and by binding to and inhibiting the DNA polymerase delta co-factor, proliferating cell nuclear antigen (PCNA). In this report, we show that adenovirus-mediated over-expression of human p21 inhibits growth factor-stimulated VSMC proliferation in vitro by efficiently arresting VSMCs in the G1 phase of the cell cycle. This p21-associated cell cycle arrest is associated both with significant inhibition of the phosphorylation of the retinoblastoma gene product (Rb) and with the formation of complexes between p21 and PCNA in VSMCs. In addition, we demonstrate that localized arterial infection with a p21-encoding adenovirus at the time of balloon angioplasty significantly reduced neointimal hyperplasia in the rat carotid artery model of restenosis. Taken together, these studies demonstrate the important role of p21 in regulating Rb phosphorylation and cell cycle progression in VSMC, and suggest a novel cytostatic gene therapy approach for restenosis and related vascular proliferative disorders.

Adenovirus-mediated transfer of the herpes simplex virus thymidine kinase gene inhibits vascular smooth muscle cell proliferation and neointima formation following balloon angioplasty of the rat carotid artery

BACKGROUND

Vascular smooth muscle cell (VSMC) proliferation following arterial injury plays a critical role in a variety of vascular proliferative disorders, including atherosclerosis and restenosis after balloon angioplasty. In this study, we tested the hypothesis that localized arterial infection at the time of balloon angioplasty with an adenovirus (ADV-tk) encoding the herpes simplex virus thymidine kinase gene (HSV-tk), followed by systemic ganciclovir administration, can inhibit VSMC proliferation and neointima formation in a well-characterized model of arterial injury and restenosis.

MATERIALS AND METHODS

The left carotid arteries of 31 male Sprague-Dawley rats were subjected to balloon angioplasty and immediately infected with 2 x 10(9) pfu of either ADV-tk or a control adenovirus that does not encode a recombinant protein (ADV-delta E1). Twenty-four hours after injury, animals from each experimental group were randomized to receive a course of systemic ganciclovir (ADV-tk/+GC, ADV delta E1/+GC) or saline (ADV-tk/-GC, ADV-delta E1/-GC). VSMC DNA synthesis was measured by 5'-bromodeoxuridine (BrdU) incorporation 2-4 days after balloon injury. The extent of restenosis, expressed as the neointima to media (I/M) area ratio was determined by digital planimetry 20 days after balloon injury in each of the four treatment groups. Immunohistochemistry using a mAb to von Willebrand factor (vWF) was used to determine the effects of ADV-tk infection and ganciclovir treatment on re-endothelialization of the carotid arteries 20 days following balloon angioplasty.

RESULTS

Forty-one percent of the medial VSMCs in the ADV-tk/-GC arteries were labeled with BrdU 4 days after balloon injury. In contrast, ADV-tk infected animals that were treated with systemic ganciclovir (ADV-tk/+GC) displayed a 40% reduction in BrdU-staining medial VSMCs (p < 0.03). I/M area ratios of the three control groups were 1.17 +/- 0.18 (ADV-tk/-GC, n = 5), 1.15 +/- 0.10 (ADV-delta E1/+GC, n = 6), and 0.91 +/- 0.08 (ADV-delta E1/-GC, n = 6). These differences were not statistically significant (p > 0.05). In contrast, the ADV-tk/+GC animals (n = 6) displayed an I/M area ratio of 0.49 +/- 0.13 which was significantly lower than that seen in each of the three control groups (p < 0.02). None of the treated animals showed evidence of significant organ toxicity at autopsy. A regenerated endothelium was observed in the ADV-tk/+GC animals 20 days after balloon injury.

CONCLUSIONS

Localized arterial infection with ADV-tk at the time of balloon angioplasty followed by systemic ganciclovir therapy reduces VSMC proliferation and neointimal expansion in the rat carotid artery injury model. Moreover, combined treatment with ADV-tk and systemic ganciclovir does not result in systemic toxicity and appears to selectively eliminate proliferating VSMCs, while preserving the capacity of the injured arterial segments to re-endothelialize within 3 weeks of injury. Taken together, these results support the feasibility of using this gene therapy approach for the treatment of human vascular proliferative disorders.

Stable delivery of physiologic levels of recombinant erythropoietin to the systemic circulation by intramuscular injection of replication-defective adenovirus

A number of inherited and acquired serum protein deficiencies including hemophilias A and B, diabetes mellitus, and the erythropoietin-responsive anemias are currently treated with repeated subcutaneous or intravenous infusions of purified or recombinant proteins. The development of an in vivo gene-transfer approach to deliver physiologic levels of recombinant proteins to the systemic circulation would represent a significant advance in the treatment of these disorders. Here we describe the construction of a replication-defective adenovirus (AdEF1hEpo) containing the human erythropoietin (hEpo) cDNA under the transcriptional control of the cellular elongation factor 1 alpha (EF1 alpha) promoter and the 4F2 heavy chain (4F2HC) enhancer. Neonatal CD-1 and adult SCID mice injected once intramuscularly (i.m.) with 10(7) to 10(9) plaque-forming units (pfu) of this virus displayed significant dose-dependent elevations of serum hEpo levels and increased hematocrits, which were stable over the 4-month time course of these experiments. Adenovirus injected i.m. remained localized at the site of injection and there was no evidence of either systemic infection or a localized inflammatory response. These results suggest that i.m. injection of recombinant replication-defective adenovirus vectors may serve as a paradigm for the treatment of human serum protein deficiencies.