Mitogen-activated protein (MAP) kinase kinase (MAPKK) activates MAP kinase in a signal transduction pathway that mediates cellular responses to growth and differentiation factors. Oncogenes such as ras, src, raf, and mos have been proposed to transform cells by prolonging the activated state of MAPKK and of components downstream in the signaling pathway. To test this hypothesis, constitutively active MAPKK mutants were designed that had basal activities up to 400 times greater than that of the unphosphorylated wild-type kinase. Expression of these mutants in mammalian cells activated AP-1-regulated transcription. The cells formed transformed foci, grew efficiently in soft agar, and were highly tumorigenic in nude mice. These findings indicate that constitutive activation of MAPKK is sufficient to promote cell transformation.

The Basic Local Alignment Search Tool (BLAST) website at the National Center for Biotechnology (NCBI) is an important resource for searching and aligning sequences. A new BLAST report allows faster loading of alignments, adds navigation aids, allows easy downloading of subject sequences and reports and has improved usability. Here, we describe these improvements to the BLAST report, discuss design decisions, describe other improvements to the search page and database documentation and outline plans for future development. The NCBI BLAST URL is http://blast.ncbi.nlm.nih.gov.

Background: Named entity recognition (NER) is an important first step for text mining the biomedical literature. Evaluating the performance of biomedical NER systems is impossible without a standardized test corpus. The annotation of such a corpus for gene/protein name NER is a difficult process due to the complexity of gene/protein names. We describe the construction and annotation of GENETAG, a corpus of 20K MEDLINE ® sentences for gene/protein NER. 15K GENETAG sentences were used for the BioCreAtIvE Task 1A Competition.

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In Xenopus oocytes, initiation of maturation is dependent on reduction of cyclic AMP-dependent protein kinase (PKA) activity and the synthesis of the mos proto-oncogene product. Mos is required during meiosis I for the activation of both maturation-promoting factor (MPF) and mitogen-activated protein kinase (MAPK).Here we show that injection of the catalytic subunit of PKA (PKAc) The events of maturation, including germinal vesicle breakdown (GVBD), chromosome condensation, and formation of the metaphase spindles during both meiosis I and II, occur upon activation of maturation-promoting factor (MPF), a complex consisting of p34cdc2 and cyclin B (see reference 55 for a review). Conversion of pre-MPF to active MPF requires phosphorylation on threonine 161 (56) and activation of the cdc25 phosphatase, which removes inhibitory phosphorylations at 15,30,37). cdc25 is itself regulated by net phosphorylation (22,25,28).MPF activation in meiosis I requires not only a reduction in PKA activity but also new protein synthesis. Following progesterone exposure, the product of the c-mos proto-oncogene is synthesized and it has been shown to account for the protein synthesis requirement for GVBD and MPF activation (49,60 MATERUILS AND METHODSOocyte injections. Xenopus laevis females were purchased from Xenopus I (Ann Arbor, Mich.). Oocytes were surgically removed and defolliculated by incubation in modified Barth solution [MBS; 88 mM NaCl, 1 mM KCI, 2.5 mM NaHCO3, 10 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid 4419

Mos is a serine-threonine protein kinase and a key regulator of meiosis. One function of Xenopus Mos is to activate mitogen-activated protein kinase (MAPK) through direct phosphorylation and activation of MAPK kinase (MAPKK). All three members of this signal cascade can individually induce hormone-independent reentry of oocytes into meiosis I. However, their inducing efficiency is reduced in the absence of protein synthesis. Here we show that de novo Mos synthesis is required for induction of meiosis I by active MAPKK or Mos-MAPK coinjection. In addition, MAPK efficiently phosphorylates Mos at Ser-3 in vitro. These results suggest that a positive feedback loop exists between MAPK and Mos during oocyte maturation. De novo synthesis of Mos, and other proteins, is required for progression from meiosis I to the metaphase arrest at meiosis II; therefore, one function of MAPK during normal Xenopus oocyte maturation might be to stimulate the synthesis or accumulation of Mos that is required for the completion of meiosis.

Abstract. We show here that tubulin is the major in vivo substrate of the tyrosine-specific protein kinase pp60 ~-~ in nerve growth cone membranes. Phosphotyrosine antibodies were used to demonstrate phosphotyrosyl residues in a subpopulation of ~-and ~-tubulin that was highly enriched in a subcellular fraction of growth cone membranes from fetal rat brain. The presence of phosphotyrosine-modified isoforms of a-and ~-tubulin in vivo was confirmed by 32p labeling of rat cortical neurons in culture. Tubulin in growth cone membranes was phosphorylated at tyrosine in endogenous membrane phosphorylation reactions (0.068 mol phosphotyrosine/mol a-tubulin and 0.045 tool phosphotyrosine/mol/~-tubulin), and phosphorylation was specifically inhibited by antibodies directed against pp60 ~-s~, which is localized in the growth cone membranes, pp60 ~-s~ was capable of directly phosphorylating tubulin as shown in immune complex kinase assays with purified brain tubulin. Phosphopeptide mapping revealed a limited number of sites of tyrosine phosphorylation in a-and/~-tubulin, with similar phosphopeptides observed in vivo and in vitro. These results reveal a novel posttranslational modification of tubulin that could regulate microtubule dynamics at the growth cone.

Mitogen-activated protein kinase (MAPK) is selectively activated by injecting either mos or MAPK kinase (mek) RNA into immature mouse oocytes maintained in the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). IBMX arrests oocyte maturation, but Mos (or MEK) overexpression overrides this block Under these conditions, meiosis I is significantly prolonged, and MAPK becomes fully activated in the absence of p34cdc2 kinase or maturationpromoting factor. In these oocytes, large openings form in the germinal vesicle adjacent to condensing chromatin, and microtubule arrays, which stain for both MAPK and centrosomal proteins, nucleate from these regions. Maturationpromoting factor activation occurs later, concomitant with germinal vesicle breakdown, the contraction of the microtubule arrays into a precursor of the spindle, and the redistribution of the centrosomal proteins into the newly forming spindle poles. These MATERIALS AND METHODSOocyte Collection, Culture, and Microinjection. B6C3 F1 female mice were injected intraperitoneally with 5 units of pregnant mare serum gonadotropin. Cumulus-enclosed oocytes were isolated 45-48 hr later and cultured in modified Whitten's medium (21) containing 0.4% BSA and 100 ,uM IBMX. For microinjection, oocytes were transferred to modified Whitten's media with Hepes (PGC Scientific, Gaithersburg, MD; specialty media) containing 5% fetal calf serum and 100 ,tM IBMX. Oocytes were injected in the cytoplasm with '10 pl of RNA (1 gg/,ul) in Dulbecco's PBS. Injected or uninjected oocytes were washed in modified Whitten's medium containing IBMX and incubated at 38.5°C in humidified 5% CO2 in air.RNA was synthesized in vitro from the mos-containing plasmid, PHTX, with T7 RNA polymerase and the RNA cap analog, 7-methyl-G(5')ppp(5')G (22). Gain-of-function mek* RNA (17) was synthesized in vitro using the same method. The RNA was precipitated twice in ethanol, then resuspended in Dulbecco's PBS.Immunofluorescence and Confocal Microscopic Analysis.Oocytes were stripped of their zonae pellucidae with acidic Tyrode's solution (pH 2.5), fixed with 1.8% paraformaldehyde in PBS (fixing solution) for 40 min at room temperature, and made permeable with 1% Triton X-100 in fixing solution for 40 min. Oocytes were washed with 0.1% Tween-20 in PBS for 20 min and incubated with 3% BSA, 10% goat serum, andAbbreviations: MAPK, mitogen-activated protein kinase; MT, microtubule; MEK, MAPK kinase; MPF, maturation-promoting factor;IBMX, 3-isobutyl-1-methylxanthine; GV, germinal vesicle; DAPI, 4',6-diamino-2-phenylindol; GVBD, GV breakdown. 4730The 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.