Genes and proteins involved in the control of meiosis

摘要

Meiosis is a process that ensures our survival. Through random segregation, crossing over and random fertilization, we are all different and that genetic variation is the basis for natural selection and evolution. In principle, meiosis is similar to mitosis; however, the additional, reductional division and the genetic exchange that occurs between homologous chromosomes means that it has a greater degree of genetic control, and, presumably, many more genes involved in its regulation. Meiosis is thus more complex than mitosis, requiring unique structures and events during each phase of the cell cycle (Chaganti et al., 1980; Uhlmann, 2001; Wolgemuth et al., 2002; Nasmyth, 2002). When meiosis goes wrong, it can lead to severe fertility problems and, through non-disjunction, aneuploidy, which is the leading cause of pregnancy loss and mental retardation in humans. It is likely that regulation and support of spermatogenesis occurs at intrinsic, extrinsic and interactive levels. However, at least with regard to spermatogenesis, it is the intrinsic programming that is thought to be the primary regulator, with the extrinsic and interactive components serving only as support (Clouthier et al., 1996; Kumar et al., 1997; Tapanainen et al., 1997; Franca et al., 1998; Krishnamurthy et al., 2000; Hwang et al., 2001; Johnston et al., 2001). In the first part of this study, key areas of the meiotic process are considered; in particular the first division and the events of prophase I. During the course of our studies it became clear that specific types of genes were consistently studied in relation to meiosis. These included transcriptional regulators, histones, cell cycle regulators, tumour suppressor genes, apoptotic genes, growth factors, hormones and their receptors, neuropeptides and enzymes involved in energy metabolism. For this reason, each of these is considered in a separate section of the following pages.