Browsing by Subject "Nucleus"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Publication
    Open Access
    Cardiac natriuretic peptides: hormones with anticancer effects that localize to nucleus, cytoplasm, endothelium, and fibroblasts of human cancers
    (Murcia : F. Hernández, 2006) Saba, S.R.; Vesely, D.L.
    Four cardiac peptide hormones, i.e., vessel dilator, long acting natriuretic peptide (LANP), kaliuretic peptide, and atrial natriuretic peptide (ANP) synthesized by the same gene decrease within 24 hours up to 97% the number of human breast, colon, pancreatic, and prostate adenocarcinoma cells as well as human small-cell and squamous carcinomas of the lung cells. These peptide hormones completely inhibit the growth of human pancreatic adenocarcinomas growing in athymic mice. Immunocytochemical investigations have revealed that LANP, vessel dilator, kaliuretic peptide and ANP localize to the nucleus and cytoplasm of human pancreatic adenocarcinomas, which is consistent with their ability to decrease DNA synthesis in the nucleus of this cancer mediated by the intracellular messenger cyclic GMP. These peptide hormones also localize to the endothelium of capillaries and fibroblasts within these cancers. These are the first growth-inhibiting peptide hormones ever demonstrated to localize to the nucleus. Their ability to decrease the activation of growth promoting substances such as Extracellular Receptor Kinase (ERK)-1/2 and Nuclear Factor Kappa Beta (NFkB) suggests that in addition to inhibiting DNA synthesis their ability to decrease the activation of growth promoting substances helps to mediate their ability to inhibit the growth of human cancers.
  • Thumbnail Image
    Publication
    Open Access
    Lipid signaling and cell responses at the nuclear level
    (Murcia : F. Hernández, 1999) Neri, L.M.; Capitani, S.; Borgatti, P.; Martelli, A.M.
    The nucleus is known to be a site for an active lipid metabolism. Although phospholipids are present in the nuclear envelope, evidence suggests that they are also located further inside the nucleus. The function of these intranuclear lipids has escaped clarification for many years. Early experiments showed that they can interact with DNA double helix affecting its thermal stability and can influence RNA synthesis in isolated nuclei. However, in the last 10 years several investigations have suggested that they may be involved in signal transduction pathways at the nuclear level and a growing body of evidence supports this hypothesis
  • Thumbnail Image
    Publication
    Open Access
    Nuclear diacylglycerol kinases: emerging downstream regulators in cell signaling networks
    (Murcia : F. Hernández, 2007) Evangelisti, C.; Bortul, R.; Falà, F.; Tabellini, G.; Goto, K.; Martelli, A.M.
    There exists an active lipid metabolism in the nucleus, which is regulated differentially from the lipid metabolism taking place elsewhere in the cell. Evidence has been accumulated that nuclear lipid metabolism is closely involved in a variety of cell responses, including proliferation, differentiation, and apoptosis. A fundamental lipid second messenger which is generated in the nucleus is diacylglycerol, that is mainly known for its role as an activator of some protein kinase C isoforms. Diacylglycerol kinases attenuate diacylglycerol signaling by converting this lipid to phosphatidic acid, which also has signaling functions. Ten mammalian diacylglycerol kinase isoforms have been cloned so far, and some of them are found also in the nucleus, either as resident proteins or after migration from cytoplasm in response to various agonists. Experiments using cultured cells have demonstrated that nuclear diacylglycerol kinases have prominent roles in cell cycle regulation and differentiation. In this review, the emerging roles played by diacylglycerol kinases in the nucleus, such as the control of G1/S phase transition, are discussed.
  • Thumbnail Image
    Publication
    Open Access
    Splicing and the single cell
    (Murcia : F. Hernández, 2000) Elliott, D.J.
    The selection of alternative splice sites is an important component of cell-specific gene regulation in eukaryotic cells. Use of splice sites can be positively and negatively regulated, and often physiologically appropriate splice site choice is achieved by a balance of the two. RNA elements controlling splice site choice are found in both exons and introns, and these determine management by the cellular splicing machinery. However, the molecular basis of how the splicing machinery responds to these signals in different cells is somewhat of a paradox. Thus far the identified proteins which bind to tissue/cell-specific regulatory elements in mammals are expressed in many different tissues, and not just in the regulating tissue. Potential tissue-specific splicing regulators have been identified by nonbiochemical means. However, alternative splicing choices are likely to be affected by subtle differences in the splicing machinery in different cells. In this review I suggest that one important factor is the ratio of proteins in different nuclear compartments, which might be established in a cell type specific fashion.
  • Thumbnail Image
    Publication
    Open Access
    The controversial nuclear matrix: a balanced point of view
    (Murcia : F. Hernández, 2002) Martelli, A.M.; Falcieri, E.; Zweyer, M.; Bortul, R.; Tabellini, G.; Cappellini, A.; Cocco, L.
    The nuclear matrix is defined as the residual framework after the removal of the nuclear envelope, chromatin, and soluble components by sequential extractions. According to several investigators the nuclear matrix provides the structural basis for intranuclear order. However, the existence itself and the nature of this structure is still uncertain. Although the techniques used for the visualization of the nuclear matrix have improved over the years, it is still unclear to what extent the isolated nuclear matrix corresponds to an in vivo existing structure. Therefore, considerable scepticism continues to surround the nuclear matrix fraction as an accurate representation of the situation in living cells. Here, we summarize the experimental evidence in favor of, or against, the presence of a diffuse nucleoskeleton as a facilitating organizational nonchromatin structure of the nucleus.