P-selectin is an endothelial cell adhehion molecule which mediates the binding of neutrophils and monocytes. Its appearance at the c d l surface can be induced within minutes by histamine and thrombin which rapidly stimul'3te the transport of 1'-selectin from intracel-M a r storage granules to the plasma nie~nbr~ine. We have recently found c3 second regulation mechanism for 1'-selectin o n moiisc cniiothelioma cells. Like E-selectin, 1'-selectin is also regulated at the level of transcription. Both selectins are induced by 1-PS or TNF-n with a maximal expression level at thc c c 4 s u r f x e 3-4 h after stimulation. Here, we report that this up-regulation of the synthesis ot P -s c k t i n also occurs iri i1i710 i n endothelium of the mouse. Analysing brain tissue, which is devoid of constitutive expression o f 1'-selectin, we found that LPS and also TNF-(L strongly induce the expression of 1'-selectin on all venular endothelial cells of the 1eptomcmingt.s dnd, at a weaker level, on some blood vessels of the brain parenchyma. Induction ot P-selectin expression could also be observed in tissues, such a s the tongue, where P-sclectin is constitutively expressed on smnll venules but only rarely on larger venules. Strong staining for P-selectin on endotheiium of all large venules was observed in tissues of LI'S m d TNF-u treated animals and staining for this newly synthesized P-selectin was enriched at the luminal surface o f these cells. Comparison of the expression pattern of LPS-induced 1'-selectin and E-selectin on blood vessels of the leptomeninges revealed that both selectins were co-induced on venular endothelium while on most arterial endothelial cells only E-selectin and not P-selectin was induced. Thus, in vivo, endothelial cells can differ in their capacity to upregulate the expression of the two endothelial selectins

During mammalian embryogenesis the trophectoderm represents the first epithelial structure formed. The cell adhesion molecule E-cadherin is ultimately necessary for the transition from compacted morula to the formation of the blastocyst to ensure correct establishment of adhesion junctions in the trophectoderm. Here, we analyzed to what extent E-cadherin confers unique adhesion and signaling properties in trophectoderm formation in vivo. Using a gene replacement approach, we introduced N-cadherin cDNA into the E-cadherin genomic locus. We show that the expression of N-cadherin driven from the E-cadherin locus reflects the expression pattern of endogenous E-cadherin. Heterozygous mice co-expressing E-and N-cadherin are vital and show normal embryonic development. Interestingly, N-cadherin homozygous mutant embryos phenocopy E-cadherin-null mutant embryos. Upon removal of the maternal E-cadherin, we demonstrate that N-cadherin is able to provide sufficient cellular adhesion to mediate morula compaction, but is insufficient for the subsequent formation of a fully polarized functional trophectoderm. When ES cells were isolated from N-cadherin homozygous mutant embryos and teratomas were produced, these ES cells differentiated into a large variety of tissue-like structures. Importantly, different epithelial-like structures expressing N-cadherin were formed, including respiratory epithelia, squamous epithelia with signs of keratinization and secretory epithelia with goblet cells. Thus, N-cadherin can maintain epithelia in differentiating ES cells, but not during the formation of the trophectoderm. Our results point to a specific and unique function for E-cadherin during mouse preimplantation development.

We have produced null mutant mouse embryonic stem cells for the cell adhesion molecule E-cadherin. Such E-cadherin−/− ES cells are defective in cell aggregation; this defect can be corrected by transfection with cDNA for either E-cadherin or N-cadherin driven by a constitutive promoter. The presence (or absence) of E-cadherin regulates the expression of the transcription factor T-brachyury, indicating that cadherins play a role in linking cell surface receptors and gene expression. Comparative analysis of the parental and the genetically altered ES cell lines was performed to examine cell differentiation and the capability to form organized tissues. While differentiating E-cadherin−/− ES cells are still able to express various early and late differentiation markers, they show a clear-cut deficiency in forming organized structures. This phenotype can be rescued by constitutive expression of E-cadherin, which results exclusively in formation of epithelia. In contrast, rescue transfectants expressing N-cadherin show no epithelial structures, instead forming neuroepithelium and cartilage. These results provide the first evidence that specific cadherins directly stimulate differentiation into certain types of tissues.

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The main etiological factor of precancerous lesion and invasive cervical cancer are oncogenic human papillomaviruses types (HPVs). The objective of this study was to establish the distribution of the most common HPVs in different cervical lesions and cancer prior to the implementation of organized population-based cervical screening and HPV vaccination in Croatia. In this study, 4,432 cervical specimens, collected through a 16-year period, were tested for the presence of HPV-DNA by polymerase chain reaction (PCR) with three sets of broad-spectrum primers and type-specific primers for most common low-risk (LR) types (HPV-6, 11) and the most common high-risk (HR) types (HPV-16, 18, 31, 33, 45, 52, 58). Additional 35 archival formalin-fixed, paraffin embedded tissue of cervical cancer specimens were analyzed using LiPA25 assay. The highest age-specific HPV-prevalence was in the group 18–24 years, which decreased continuously with age (P<0.0001) regardless of the cytological diagnosis. The prevalence of HR-HPV types significantly increased (P<0.0001) with the severity of cervical lesions. HPV-16 was the most common type found with a prevalence (with or without another HPV-type) of 6.9% in normal cytology, 15.5% in atypical squamous cells of undetermined significance, 14.4% in low-grade squamous intraepithelial lesions, 33.3% in high-grade squamous intraepithelial lesions, and 60.9% in cervical cancer specimens (P<0.0001). This study provides comprehensive and extensive data on the distribution of the most common HPV types among Croatian women, which will enable to predict and to monitor the impact of HPV-vaccination and to design effective screening strategies in Croatia.