Mos is an upstream activator of mitogenactivated protein kinase (MAPK) and, in mouse oocytes, is responsible for metaphase II arrest. This activity has been likened to its function in Xenopus oocytes as a component of cytostatic factor. Thus, Mos-deficient female mice are less fertile and oocytes derived from these animals fail to arrest at metaphase II Here we show that maturing MOS-'-oocytes fail to activate MAPK throughout meiosis, while p34edc2 kinase activity is normal until late in metaphase II when it decreases prematurely. Phenotypically, the first meiotic division of MOS-/-oocytes frequently resembles mitotic cleavage or produces an abnormally large polar body. In these oocytes, the spindle shape is altered and the spindle fails to translocate to the cortex, leading to the establishment of an altered cleavage plane. Moreover, the first polar body persists instead of degrading and sometimes undergoes an additional cleavage, thereby providing conditions for parthenogenesis. These studies identify meiotic spindle formation and programmed degradation of the first polar body as new and important roles for the Mos/MAPK pathway.The mos protooncogene encodes a protein serine/threonine kinase (1) and Mos is expressed at high levels in oocytes undergoing meiotic maturation (2,3). InXenopus oocytes, Mos has been shown to function as a meiotic initiator (4, 5) and an active component of cytostatic factor (CSF) (6), an activity that is responsible for the arrest of an unfertilized egg at metaphase II of meiosis (7). More recently, mitogen-activated protein kinase (MAPK), which is highly activated throughout oocyte maturation (8-12), has been identified as one of the major downstream targets of Mos (13)(14)(15)(16)(17). Mos has been implicated in the activation and stabilization of p34cdc2 kinase as maturation promoting factor (MPF) (4,(18)(19)(20), and evidence for the mutual dependency between MPF and the Mos/MAPK pathway in Xenopus oocytes has been reported (8,21,22).More recently, it has been shown that oocytes from mice homozygously deficient in mos (MOS-/-) fail to arrest at metaphase II and undergo parthenogenetic activation (23,24). These observations clearly demonstrated that Mos is an active component of CSF, but left unclear whether Mos functions prior to metaphase II arrest as it does in Xenopus.We generated MOS-'-mice and confirmed previous reports (23,24) that oocytes from these animals fail to arrest at metaphase II and instead undergo parthenogenetic activation.Also we show that maturing oocytes from MOS-1-mice fail to activate MAPK, while p34cdc2 kinase activation is normal until metaphase, when it decreases prematurely. Moreover, in MOS-'-oocytes, we observe that the first polar bodies can be abnormally large and sometimes undergo an additional cleavage instead of undergoing rapid degeneration. Thus, in addition to CSF activity, Mos/MAPK are required for regulating the size and degradation of the first polar body. MATERIALS AND METHODSGeneration of MOS-1-Knockout Mice. A replacement-type ...

The mos proto-oncogene product, pp39mos, is a protein kinase and has been equated with cytostatic factor (CSF), an activity in unfertilized eggs that is thought to be responsible for the arrest of meiosis at metaphase II. The biochemical properties and potential substrates of pp39mos were examined in unfertilized eggs and in transformed cells in order to study how the protein functions both as CSF and in transformation. The pp39mos protein associated with polymers under conditions that favor tubulin oligomerization and was present in an approximately 500-kilodalton "core" complex under conditions that favor depolymerization. beta-Tubulin was preferentially coprecipitated in pp39mos immunoprecipitates and was the major phosphorylated product in a pp39mos-dependent immune complex kinase assay. Immunofluorescence analysis of NIH 3T3 cells transformed with Xenopus c-mos showed that pp39mos colocalizes with tubulin in the spindle during metaphase and in the midbody and asters during telophase. Disruption of microtubules with nocodazole affected tubulin and pp39mos organization in the same way. It therefore appears that pp39mos is a tubulin-associated protein kinase and may thus participate in the modification of microtubules and contribute to the formation of the spindle. This activity expressed during interphase in somatic cells may be responsible for the transforming activity of pp39mos.

Two triterpenoids from Acanthopanax trifoliatus, an edible medicinal plant from Southeast Asia, attenuated lipopolysaccharides-induced inflammation in murine macrophage RAW246.7 cells and tetradecanoylphorbolacetate-induced mouse ear edema.

Most directly oncogenic retroviruses contain single, autonomous transforming (onc) genes (1). However, three oncogenic retroviruses contain two genes with oncogenic potential, namely the avian carcinoma viruses MH2 (2-5) and OK10 (6, 7) and avian erythroblastosis virus (AEV) (8, 9). The 5.5-kilobase (kb) RNA genome of MH2 (10) has the genetic structure Agag-mht-myc (2-5). One of the two genes with potential transforming function encoded by MH2 is a 3-kb Agag-mht gene, defined by a p100 protein product (11). A close structural relative of this gene (5, 12) is the only transforming gene of murine sarcoma virus MSV 3611 (13).The other MH2 gene is a myc-related gene, termed 8gag-myc, which is discontiguous. This gene includes a gag-derived 5' exon of only six gag codons (therefore 8gag) and a 3' 1.6-kb myc exon that is colinear with the two 3'-terminal exons of chicken proto-myc (5, 14). This gene is expressed via a subgenomic 2.6-kb mRNA as a 57,000-dalton (p57) protein product (15-18). The 7.5-kb RNA genome of OK10 virus (19) contains two overlapping myc-related genes (7); a contiguous gag-Apol-myc gene, which encodes a p200 protein; and a discontiguous 8gag-myc gene, which as in MH2 is also expressed as a subgenomic 3.5-kb mRNA encoding a p57protein (6,17,18 Here we analyze MH2 to determine whether it could serve as a model for multigene carcinogenesis. Several lines of evidence indicate that the 8gag-myc gene of MH2 is necessary for oncogenicity and that it transforms fibroblasts without Agag-mht as helper gene. (1) The 8gag-myc gene of MH2 is shared by MH2 and OK10 (7). Since both viruses have similar oncogenic spectra yet each has a specific second gene with potential transforming function, it follows that 8gag-myc is essential for common oncogenic properties (7).(ii) A study that has isolated MH2-transformed fibroblasts that express high levels of the 8gag-myc product p57 but no detectable Agag-mht product pl00 has concluded that p57 is sufficient for transforming function (15 6389The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.