ABSTRACT
Nucleosomes are the basic structural units of eukaryotic chromatin. In recent years, it has become evident that nucleosomes and their position, in concert with other epigenetic mechanisms (such as DNA methylation, histone modifications, changes in histone variants, as well as small noncoding regulatory RNAs) play essential roles in the control of gene expression. Here, we discuss the mechanisms and factors that regulate nucleosome position and gene expression in normal and cancer cells.
Subject(s)
Chromatin/genetics , Gene Expression Regulation, Neoplastic , Neoplasms/genetics , Neoplasms/pathology , Nucleosomes/genetics , Animals , HumansABSTRACT
Apoptosis is a form of cell death, characterized by morphological and biochemical changes. Apoptosis occurs in the normal testis and in response to different agents. In this study, we investigated the effect of gonadotropin-releasing hormone (GnRH) in testicular apoptosis in the goldfish. GnRH is a decapeptide that is expressed in different tissues, including gonads in mammalian and non-mammalian species. While GnRH is considered to be a paracrine mediator of ovarian follicular atresia, the role of GnRH in the testis is less clear. In the present study, treatments with native salmon GnRH and chicken GnRH-II increased DNA fragmentation (a hallmark of apoptosis) in the mature goldfish testis. On the other hand, gonadotropin hormone was found to act as survival factor, by decreasing spontaneous and GnRH-induced DNA fragmentation in the goldfish testis. The results demonstrate that GnRH plays an important paracrine role in the control of apoptosis in the goldfish testis.
Subject(s)
Apoptosis/drug effects , Chickens , Goldfish/physiology , Gonadotropin-Releasing Hormone/analogs & derivatives , Gonadotropin-Releasing Hormone/pharmacology , Salmon , Testis/drug effects , Animals , Cells, Cultured , Chorionic Gonadotropin/pharmacology , Male , Testis/cytologyABSTRACT
Apoptosis is a form of programmed cell death that is essential for the development of the embryo and adult tissue plasticity. In adults, it is observed mainly in those tissues undergoing active differentiation such as the hematopoietic system, testis, ovary, and intestinal epithelium. Apoptosis can be triggered by many factors, such as hormones, cytokines, and drugs, depending on the type of the cell. While the intracellular signaling mechanisms may vary in different cells, they all display similar morphological and biochemical features at the later stages of the apoptotic process. This review focuses on the factors controlling ovarian apoptosis, emphasizing observations made on GnRH-induced apoptotic process in goldfish follicles.
