High impact information on nos

• We show that nos- germ cells are unable to attenuate the cell cycle and instead continue dividing [1].
• Supporting the conclusion that Sxl is an important target for nos repression, ectopic, premature expression of Sxl protein in germ cells disrupts migration and stimulates mitotic activity [1].
• It has previously been shown that germ cells in embryos derived from nos mutant mothers do not migrate to the primitive gonad and prematurely express several germline-specific markers [1].
• Novel functions of nanos in downregulating mitosis and transcription during the development of the Drosophila germline [1].
• These and other observations suggest that pum acts by recognizing the NRE and then recruiting nos [2].

Biological context of nos

• These nos response elements (NREs) are both necessary and sufficient to confer nos-dependent regulation, the degree of regulation determined by the number and quality of the elements and the level of nos in vivo [3].
• As these phenotypes are indistinguishable from those produced by nos mutation, we conclude that Pum acts together with Nos to regulate these germline-specific events [4].
• In this report, we show that Nos interacts with Cup, which is required for normal development of the ovarian germline cells. nos and cup also interact genetically--reducing the level of cup activity specifically suppresses the oogenesis defects associated with the nos(RC) allele [5].
• Analogous to their function in body patterning, nos and pum require each other to control dendrite morphogenesis, a process likely to involve translational regulation of nos itself [6].
• This maternally provided Nanos protein is present in germ cells throughout embryogenesis [7].

Anatomical context of nos

• Here we show that maternally deposited Nanos protein is essential for germ cell migration [7].
• Nanos and Pumilio have critical roles in the development and function of Drosophila germline stem cells [7].
• To avoid inappropriate activation of nos, osk activity must appear only at the posterior pole of the oocyte, where the osk mRNA becomes localized during oogenesis [8].
• We used sucrose density gradient sedimentation to ascertain whether unlocalized nos mRNA is excluded from polysomes and therefore repressed during translational initiation [9].
• The loss of germline stem cells in nos mutant mothers appears to be due to a progressive degeneration of the plasma membrane [10].

Physical interactions of nos

• In this report we use protein-protein and protein-RNA interaction assays in yeast and in vitro to show that Nanos forms a ternary complex with the RNA-binding domain of Pumilio and the NRE [11].
• We show that Oskar prevents the rapid deadenylation of nanos mRNA by precluding its binding to Smaug, thus leading to its stabilization and translation [12].
• In this report, we show that Pumilio and Nanos bind to an element in the 3' UTR to repress Cyclin B mRNA [13].

Regulatory relationships of nos

• When active inappropriately at the anterior pole, nos can also block expression of the anterior determinant bicoid (bcd) [3].
• To determine if nanos activity represses translation by altering the polyadenylation state of hunchback mRNA, we injected various in vitro transcribed RNAs into Drosophila embryos and determined changes in polyadenylation [14].
• smaug protein represses translation of unlocalized nanos mRNA in the Drosophila embryo [15].
• The nanos translational control element represses translation in somatic cells by a Bearded box-like motif [16].

Other interactions of nos

• Based on these and other results, we argue that nos acts as a morphogen, controlling hb expression (and hence abdominal pattern) as a function of its concentration-dependent interaction with the NREs [3].
• While orthologs of Drosophila bicoid and nanos play a conserved role in anteroposterior (AP) patterning within at least a subset of Diptera, conservation of this process has not yet been demonstrated outside of the flies [17].
• In the absence of nanos high levels of Hb protein repress the abdomen-specific genes knirps and giant [18].
• This protection of Hsp83 RNA occurs in wild-type embryos and embryos produced by females carrying the maternal effect mutations nanos and pumilio, which eliminate components of the posterior polar plasm without disrupting polar granule integrity [19].
• We have previously reported that nos is required to keep the Sex-lethal establishment promoter, Sxl-Pe, off in the germline of both sexes [20].
• Rumpelstiltskin associates with nanos mRNA in vitro and in vivo, and binding by Rumpelstiltskin correlates with localization element function in vivo [21].

Analytical, diagnostic and therapeutic context of nos

• We used cytoplasmic transplantation assays to demonstrate that nanos activity is found in posterior poleplasm of five diverse Dipteran species [22].
• Developmental northern blots show that Hro-nos, like nanos, is a maternal transcript that decays rapidly during early development [23].

References