Friedrich Miescher Prize awardee lecture review. A conserved family of nuclear export receptors mediates the exit of messenger RNA to the cytoplasm

The distinguishing feature of eukaryotic cells is the segregation of RNA biogenesis and DNA replication in the nucleus, separate from the cytoplasmic machinery for protein synthesis. As a consequence, messenger RNAs (mRNAs) and all cytoplasmic RNAs from nuclear origin need to be transported from their site of synthesis in the nucleus to their final cytoplasmic destination. Nuclear export occurs through nuclear pore complexes (NPCs) and is mediated by saturable transport receptors, which shuttle between the nucleus and cytoplasm. The past years have seen great progress in the characterization of the mRNA export pathway and the identification of proteins involved in this process. A novel family of nuclear export receptors (the NXF family), distinct from the well-characterized family of importin β-like proteins, has been implicated in the export of mRNA to the cytoplasm. Received 23 January 2001; received after revision 12 April 2001; accepted 12 April 2001     

A note of the dual effect of prostaglandin E1 on the responses of the guinea-pig vas deferens to nerve stimulation

Résumé La prostaglandine E₁ diminue les potentiels de jonction excitateurs du muscle lisse du vas deferens de cobaye en réponse à une stimulation nerveuse, mais provoque aussi une dépolarisation modérée de ce tissu. L'effet inhibiteur de la drogue sur la réponse motrice de cet organe à une stimulation nerveuse est attribué à la 1^e de ces actions. L'effet stimulant sur la réponse motrice parfois constaté, est attribué à la seconde action.

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The generous hospitality of ProfessorEdith Bülbring F. R. S. is gratefully acknowledged. The investigation was supported by a grant to ProfessorBülbring from the Medical Research Council.     

K252a: A new blocker of the cell-cycle at G1 phase in a human hepatoma cell line

The administration of 200 nM K252a to HuH7 suppressed the proliferation of the cells almost completely. The uptake of [³H]thymidine was inhibited, and flow cytometry revealed only one peak at 2C on day 3 after treatment with 100 nM K252a. The expression of proto-oncogene c-myc was not reduced. Despite the blockage at G1, both the size of the cells and the amount of cell protein had increased by 4 times by day 3 after treatment with K252a, while the cells secreted albumin and -fetoprotein into the medium as usual. These results show that K252a can increase the cell size of HuH7 without losing its function by blocking the cell cycle at G1 phase.     

Natural killer-like activity in human cultured lymphoid cells propagated in the presence of interleukin-2: acquired resistance to prostaglandin E2- or dexamethasone-mediated suppression

The cytotoxic activity of human peripheral blood lymphocytes against the natural killer-sensitive target K562 was suppressed both by prostaglandin E2 and dexamethasone. On the other hand, cultured lymphoid cells propagated in the presence of interleukin-2 showed strong cytotoxic reactivity against K562 targets, and were resistant to prostaglandin E2- or dexamethasone-mediated suppression.     

Natural killer-like activity in human cultured lymphoid cells propagated in the presence of interleukin-2: acquired resistance to prostaglandin E2- or dexamethasone-mediated suppression

Summary The cytotoxic activity of human peripheral blood lymphocytes against the natural killer-sensitive target K562 was suppressed both by prostaglandin E₂ and dexamethasone. On the other hand, cultured lymphoid cells propagated in the presence of interleukin-2 showed strong cytotoxic reactivity against K562 targets, and were resistant to prostaglandin E₂- or dexamethasone-mediated suppression.