Cell cycle arrest at G 2 M followed by apoptosis caused by Biology Diagrams To await fertilization, oocytes have to maintain a cell cycle arrestalso named cytostatic factor or CSF arrest (Schmidt et al, 2006)-for an extended time in metaphase II. Sgo2 localized by Mps1
In most vertebrates, oocytes await fertilization while arrested at metaphase of meiosis II. This resting state can be stable for many hours and depends on a cytoplasmic activity termed cytostatic factor (CSF). Recently, members of the novel Emi/Erp family of proteins have been put forward as important components of CSF. Under arrest: cytostatic factor (CSF)-mediated metaphase arrest in vertebrate eggs. showed that the arrest of cell cycle progression in egg extracts by the DNA replication checkpoint could be restored if a "critical nuclear density" was added to the extracts. Subsequent work by Minshull and colleagues (1994), as described above
Cytostatic factor: An activity that puts the cell cycle on hold Biology Diagrams
Almost 30 years ago, cytostatic factor (CSF) was identified as the activity responsible for the MII arrest, yet today its molecular make-up remains mysterious. Ten years ago, both Mos, a MAP kinase kinase kinase, and MAP kinase were shown to be capable of blocking a one-cell embryo in metaphase, and subsequent work has shown that they are
Spindle checkpoint proteins Mad1 and Mad2 are required for cytostatic factor-mediated metaphase arrest. J Cell Biol 163: 1231-1242. Article CAS Google Scholar Tunquist BJ, Maller JL . (2003
New insight into metaphase arrest by cytostatic factor: from ... Biology Diagrams
Mad1 and Mad2 arrest cleaving Xenopus embryos in metaphase. Mad1 and Mad2 proteins are present in the early embryo even though nocodazole does not affect cell cycle progression until the gastrula stage (Minshull et al., 1994; Clute and Masui, 1995).However, if CSF components are introduced into cells of the embryo, the cell cycle arrests in metaphase of the next mitosis (Masui and Markert It is shown that the zinc fluxes work, in part, by altering the activity of the cytostatic factor (CSF), the cellular activity required for the establishment and maintenance of metaphase II arrest in the mature, unfertilized egg, which supports the conclusion that zinc itself, through its interaction with EMI2, is a central component of the CSF.
The second causes cell cycle arrest when injected into a mitotically dividing embryo, leading to its designation as cytostatic factor (CSF) (see Fig. 1). This arrest is characterized by the presence of a metaphase spindle and high Cdk1 activity in the injected cell, just like the physiological CSF arrest that occurs in meiosis II. Oocytes from higher chordates, including man and nearly all mammals, arrest at metaphase of the second meiotic division before fertilization. This arrest is due to an activity that has been termed 'Cytostatic Factor'. Cytostatic Factor maintains arrest through preventing loss in Maturation-Promoting Factor (MPF; CDK1/cyclin B). Physiologically, Cytostatic Factor - induced metaphase arrest is
