Gene De-Repression

A case-control study identifying chromosomal polymorphic variations as forms of epigenetic alterations associated with the infertility phenotype

“…Heterochromatin (containing repressed segments of DNA) and euchromatin (consisting of expressed/active segments) are expressions of the degree of nuclear differentiation within individually differentiated cells (44,45). Cellular processes involving derepression of previously repressed genes include the activation/expression of the sperm genome in the embryo, viral oncogenesis, and activation of Y chromosome genes during fetal development of a male child (34,46,47).…”

Para-Endocrine Tumor Activity with Emphasis on Ectopic ADH Secretion

“…The genetic potentials and expressions in embryonic and fetal cells vary in relation to cellular differentiation and acquisition of specific functions. These cellular processes underly the epigenetic control of the genome and lor particular organ tissues a selective derepression of an otherwise fully repressed genome occurs, allowing the cell to carry out specific functions [33]. Through unwinding, DNA can serve as template for synthesis of messenger RNA (ni-RNA) and transfer RNA (t-RNA) necessary for essential cellular functions such as ribosomal RNA and protein synthesis ( fig.…”

“…Accordingly, in most body cells a yet unknown repressor substance prevents synthesis of messenger RNA for insulin or hemoglobin production, or for synthesis of various polypeptide hormones and proteins (enzymes). In this respect, histone proteins may function as nonspecific repressors of DNA template by 'turning off' some undesired specific information of DNA [33], Therefore, in postnatal life, a permanent regulation and control (repression, suppression) of potentially available, but undesired genetic information in regard to protein synthesis and other cellular metabolic activities are exercised. Such a controlling mechanism may operate by depression of different sets of active genes leading to reduced numbers of RNA messages for biochemical cellular function [80].…”

“…Moreover, in certain malignancies (carcinoma of colon, primary Physiologically, it appears that so-called regulator genes induce production of macromolecular basic proteins (histones) which connect structurally via ionic linkages with the active genes (operator genes) of DNA. Through histones acting as repressors, unwinding of DNA is prevented, and double-stranded DNA cannot serve as template for synthesis hepatoma of liver, Hodgkin's lymphoma) previously repressed, embryonic RNA species reappear as evidenced by production of embryonic-fetal cell surface antigens (carcino-embryonic antigen, CEA) by such malignant cells [33,38].…”

“…At present, the 'abnormal gene action theory', also termed 'gene de repression theory' [33,39,77], considering disturbance in repression of undesired gene information and gene control in some cancer types as the cause for para-endocrine activity, is favored by many. Accordingly, malig nancy can be induced for instance by carcinogens such as polycyclic hydro carbons, hormones (estrogens, diethylstilbestrol), and oncogenic viruses of DNA and RNA type; within the course of this process of malignant de generation and growth, the immunologic status of the host also plays a major role.…”