Browsing by Subject "Embryogenesis"

Now showing 1 - 4 of 4
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    Correspondence of gradual developmental increases of expression of galectin-reactive glycoconjugates with alterations of the total contents of the two differentially regulated galectins in chicken intestine and liver as indication for overlapping functions
    (Murcia : F. Hernández, 1999) Lips, K.S.; Kaltner, H.; Reuter, G.; Stierstorfer, B.; Sinowatz, F.; Gabius, H.J.
    The duplication of genes for recognition molecules and the ensuing diversification of the members of such families generate complex groups of homologous proteins. One example are galactosidespecific lectins whose sequences display constant features related to sugar binding, the galectins. Based on the inverse abundance of the chicken galectins CG-14 and CG-16 in adult intestine and liver, these two lectins represent a model to comparatively study expression of the related proteins and the galectin-reactive sites (glycoproteins and glycolipids) biochemically and histochemically. Functional overlap andtor acquisition of distinct functions would be reflected in qualitative andlor quantitative aspects of ligand display. Using five different stages of embryogenesis, differential regulation of the two galectins was detected in liver and intestine. The clear preference for one galectin (CC-14) was observed in intestine already at rather early stages, whereas equivalence for both proteins was noted in liver from day 12 to day 18 prior to hatching, as seen by ELISA assays and Western blot analysis. Presentation of galectin-reactive glycoproteins showed a tendency for gradual increase in both organs. Galectin-blotting analysis revealed primarily very similar patterns of positive bands at the different stages of development and only few quantitative and qualitative changes. The reactivity of glycolipids in a solid-phase assay was more variable, even surpassing the response of extracts of the adult organ at several embryonic stages. While the localization patterns of the galectins and galectinreactive sites were nearly indistinguishable in the liver, intestinal tissue differed with respect to the placement and accessibility of binding sites. Thus, the results suggest a differential regulation of galectin activities in the two organs. As a sum they resemble the course of development of availability of glycoprotein ligands in vitro. These findings support the notion for a partial functional redundancy in this family. The described approach to employ galectin-specific antibodies and the labeled galectins as tools to assess presentation of ligands is suggested to be of general relevance to address the question of distinct vs. overlapping functions of related recognition molecules.
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    Hepatocyte nuclear factor-1B(HNF-1B) in human urogenital organs, Its expression and role in embryogenesis and tumorigenesis
    (Murcia : F. Hernández, 2009) Kato, Noriko; Motoyama, Teiichi
    Molecules responsible for embryogenesis are often involved in tumorigenesis. Recent exhaustive cDNA microarray analyses in human neoplasms expanded knowledge of such molecules. Hepatocyte nuclear factor-1ß (HNF-1ß) is a homeobox transcription factor that functions as a homodimer or heterodimer with HNF-1a. In contrast to HNF-1a, HNF-1ß is very weakly expressed in the liver and is commonly expressed in the kidneys. During human embryonic stage, HNF-1ß plays an important role in organogenesis, especially of the urogenital system. In the human fetus, HNF-1ß expression is common in mesonephric duct derivatives and metanephros (permanent kidneys). HNF-1ß germline mutations cause malformations of these structures. Recent microarray analyses have disclosed that HNF-1ß is aberrantly up-regulated in clear cell carcinoma of the ovary, which is a carcinoma of müllerian nature, but which was initially misnamed “mesonephroma”. HNF-1ß is also expressed in ovarian endometriosis, which is a probable origin of clear cell carcinoma. On the other hand, HNF-1ß is downregulated in renal neoplasms, such as chromophobe cell carcinoma. In this review, we first summarize HNF-1ß expression in the developing urogenital system of the human embryo. Then, we describe the HNF-1ß status in human urogenital neoplasms and discuss its role in tumorigenesis.
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    Relationships between stem cells and cancer stem cells
    (Murcia : F. Hernández, 2004) Crowe, D.L.; Parsa, B.; Sinha, U.K.
    Stem cells have been shown to exist in a variety of tissues. Recent studies have characterized stem cell gene expression patterns, phenotypes, and potential therapeutic uses. One of the most important properties of stem cells is that of self renewal. This raises the possibility that some of the clinical properties of human tumors may be due to transformed stem cells. Similar signaling pathways may regulate self renewal in normal and transformed stem cells. These rare transformed stem cells may drive the process of tumorigenesis due to their potential for self renewal. There are important ramifications for clinical cancer treatment if the growth of solid tumors is at least partially dependent on a cancer stem cell population. In the cancer stem cell model, tumor recurrence may be due to the non-targeted stem cell compartment repopulating the tumor. If cancer stem cells can be prospectively identified and isolated, it should be possible to identify therapies that will selectively target these cells.
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    The role of focal adhesion Kinase in early development
    (Murcia : F. Hernández, 2010) Chatzizacharias, Nikolaos A.; Kouraklis, Gregory P.; Theocharis, Stamatios E.
    FAK is a tyrosine kinase enzyme demonstrated to play an important regulatory role in several basic cellular activities. Scientific evidence have suggested that FAK possessing a central position in the integrin signaling cascade, is responsible, at least in part, for the modulation of cellular proliferation, protection from apoptosis, adhesion, spreading and migration. The role of FAK in the development of different species, including human, is under study. Various published data supported the role of the molecule in the development of the placenta, as well as of several organ systems, like the musculoskeletal, nervous, cardiovascular, genitourinary and respiratory organ systems. Additionally, FAK has been shown to be implicated in the pathophysiology of pregnancy related disorders and congenital neonatal diseases and defects. The purpose of this article is a comprehensive review of the existing literature with a view to the future and the potential conclusions that can be drawn by the study of FAK signaling on the events of early life and species development.