Human DNA ligase and DNA polymerase as molecular targets for heavy metals and anticancer drugs

DNA ligase and DNA polymerase play important roles in DNA replication, repair, and recombination. Frequencies of spontaneous and chemical- and physical-induced mutations are correlated to the fidelity of DNA replication. This dissertation elucidates the mechanisms of the DNA ligation reaction by DNA ligases and demonstrates that human DNA ligase I and DNA polymerase $\alpha$ are the molecular targets for two metal ions, Zn$\sp{2+}$ and Cd$\sp{2+},$ and an anticancer drug, F-ara-ATP.^ Human DNA ligases were purified to homogeneity and their AMP binding domains were mapped. Although their AMP-binding domains are similar, there could be difference between the two ligases in their DNA binding domains.^ The formation of the AMP-DNA intermediate and the successive ligation reaction by human DNA ligases were analyzed. Both reactions showed their substrate specificity for ligases I and II, required Mg2+, and were inhibited by ATP.^ A protein inhibitor from HeLa cells and specific for human DNA ligase I but not ligase II and T4 ligase was discovered. It reversibly inhibited DNA ligation activity but not the AMP-binding activity due to the formation of a reversible ligase I-inhibitor complex.^ F-ara-ATP inhibited human DNA ligase I activity by competing with ATP for the AMP-binding site of DNA ligase I, forming a ligase I-F-ara-AMP complex, as well as when it was incorporated at 3$\sp\prime$-terminus of DNA nick by DNA polymerase $\alpha.$^ All steps of the DNA ligation reaction were inhibited by Zn$\sp{2+}$ and Cd$\sp{2+}$ in a concentration-dependent manner. Both ions did not show the ability to change the fidelity of DNA ligation reaction catalyzed by human DNA ligase I. However, Zn$\sp{2+}$ and Cd$\sp{2+}$ showed their contradictory effects on the fidelity of the reaction by human DNA polymerase $\alpha.$ Zn$\sp{2+}$ decreased the frequency of misinsertion but less affected that of mispair extension. On the contrary, Cd$\sp{2+}$ increased the frequencies of both misinsertion and mispair extension at very low concentration. Our data provided strong evidence in the molecular mechanisms for the mutagenicity of zinc and cadmium, and were comparable with the results previously reported. ^

Biological effects of PEA3 expression in {\it HER-2\/}/{\it neu\/}-overexpressing human cancer cells and the molecular mechanisms of PEA3-mediated transcriptional repression on {\it HER-2\/}/{\it neu\/}

HER-2/neu is a receptor tyrosine kinase highly homologous with epidermal growth factor receptor. Overexpression and/or amplification of HER-2/neu has been implicated in the genesis of a number of human cancers, especially breast and ovarian cancers. Transcriptional upregulation has been shown to contribute significantly to the overexpression of this gene. Studies on the transcriptional regulation of HER-2/neu gene are important for understanding the mechanism of cell transformation and developing the therapeutic strategies to block HER-2/neu-mediated cancers. PEA3 is a DNA binding transcriptional factor and its consensus sequence exists on the HER-2/neu promoter. To examine the role of PEA3 in HER-2/neu expression and cell transformation, we transfected PEA3 into the human breast and ovarian cancer cells that overexpress HER-2/neu and showed that PEA3 dramatically represses HER-2/neu transcription. PEA3 suppresses the oncogenic neu-mediated transformation in mouse fibroblast NIH 3T3 cells. Expression of PEA3 selectively blocks the growth of human cancer cells that overexpress HER-2/neu and inhibits their colony formation. It does not occur in the cancer cells expressing basal level of HER-2/neu. Further studies in the orthotopic ovarian cancer model demonstrated that expression of PEA3 preferentially inhibits growth and tumor development of human cancer cells that overexpress HER-2/neu, the tumor-bearing mice survived significantly longer if treated by injection of the PEA3-liposome complex intraperitoneally. Immunoblotting and immunohistochemical analysis of the tumor tissues indicated that PEA3 mediates the tumor suppression activity through targeting HER-2/neu-p185. Thus, PEA3 is a negative regulator of HER-2/neu gene expression and functions as a tumor suppressor gene in the HER-2/neu-overexpressing human cancer cells.^ The molecular mechanisms of PEA3 mediated transcriptional repression were investigated. PEA3 binds specifically at the PEA3 site on HER-2/neu promoter and this promoter-binding is required for the PEA3 mediated transcriptional repression. Mutation of the PEA3 binding site on HER-2/neu promoter causes decreased transcriptional activity, indicating that the PEA3 binding site is an enhancer-like element in the HER-2/neu-overexpressing cells. We therefore hypothesized that in the HER-2/neu-overexpressing cells, PEA3 competes with a transactivator for binding to the PEA3 site, preventing the putative factor from activating the transcription of HER-2/neu. This hypothesis was supported by the data which demonstrate that PEA3 competes with another nuclear protein for binding to the HER-2/neu promoter in vitro, and expression of a truncated protein which encodes the DNA binding domain of PEA3 is sufficient to repress HER-2/neu transcription in the HER-2/neu-overexpressing human cancer cells. ^

Family Business in Mexico: Responses to Human Resource Limitations and Management Succession

Indigenous firms in Mexico, as in most developing countries, take the shape of family businesses. Regardless of size, the most predominant ones are those owned and managed by one or more families or descendent families of the founders. From the point of view of economics and business administration, family business is considered to have variety of limitations when it seeks to grow. One of the serious limitations is concerning human resource, which is revealed at the time of management succession. Big family businesses in Mexico deal with human resource limitations adopting measures such as the education and training of the successors, the establishment of management structure that makes control by the owner family possible and divisions of roles among the owner family members, and between the owner family members and the salaried managers. Institutionalization is a strategy that considerable number of family businesses have adopted in order to undergo the succession process without committing serious errors. Institutionalization is observed in such aspects as the establishment of the requisite condition to be met by the candidate of future successor and the screening by an institution which is independent of the owner family. At present these measures allow for the continuation of family businesses in an extremely competitive environment.

Human creation, imagination and autonomy: a brief introduction to Castoriadis’ social and psychoanalytical philosophy

During the last decade Castoriadis’ questioning has become a reference point in contemporary social theory. In this article I examine some of the key notions in Castoriadis’ work and explore how he strives to develop a theory on the irreducible creativity in the radical imagination of the individual and in the institution of the social-historical sphere. Firstly, I briefly discuss his conception of modern capitalism as bureaucratic capitalism, a view initiated by his criticism of the USSR regime. The following break up with Marxist theory and his psychoanalytic interests empowered him to criticize Lacan and read Freud in an imaginative, though unorthodox, fashion. I argue that this critical enterprise assisted greatly Castoriadis in his conception of the radical imaginary and in his unveiling of the political aspects of psychoanalysis. On the issue of the radical imaginary and its methodological repercussions, I’m focusing mainly on the radical imagination of the subject and its importance in the transition from the ‘‘psychic’’ to the ‘‘subject’’. Taking up the notion of “Being” as a starting point, I examine the notion of autonomy, seeking its roots in the ancient Greek world. By looking at notions such as “praxis”, “doing”, “project” and “elucidation”, I show how Castoriadis sought to redefine revolution as a means for social and individual autonomy. Finally I attempt to clarify the meaning of “democracy” and “democratic society” in the context of the social imaginary and its creations, the social imaginary significations.

Principles of human genetics;

Includes bibliographies.

On the power, wisdom and goodness of God, as manifested in the adaptation of external nature to the moral and intellectual constitution of man,

Mode of access: Internet.

Mathematical tables for research workers in human genetics,

Mode of access: Internet.

On the power, wisdom and goodness of God : as manifested in the adaptation of external nature to the moral and intellectual constitution of man /

Mode of access: Internet.

On the power, wisdom and goodness of God as manifested in the adaptation of external nature, to the moral and intellectual constitution of man.

Mode of access: Internet.

On the power, wisdom and goodness of God : as manifested in the adaptation of external nature to the moral and intellectual constitution of man /

Mode of access: Internet.

Social and economic aspects of Swedish population movements, 1750-1933,

Mode of access: Internet.

E-Government, targeting and data profiling: Policy and ethical issues of differential treatment

Networked information and communication technologies are rapidly advancing the capacities of governments to target and separately manage specific sub-populations, groups and individuals. Targeting uses data profiling to calculate the differential probabilities of outcomes associated with various personal characteristics. This knowledge is used to classify and sort people for differentiated levels of treatment. Targeting is often used to efficiently and effectively target government resources to the most disadvantaged. Although having many benefits, targeting raises several policy and ethical issues. This paper discusses these issues and the policy responses governments may take to maximise the benefits of targeting while ameliorating the negative aspects.