No abstract

In eukaryotes, entry into mitosis is induced by cyclin Bbound Cdk1, which is held in check by the protein kinase, Wee1. In budding yeast, Swe1 (Wee1 ortholog) is targeted to the bud neck through Hsl1 (Nim1-related kinase) and its adaptor Hsl7, and is hyperphosphorylated prior to ubiquitin-mediated degradation. Here, we show that Hsl1 and Hsl7 are required for proper localization of Cdc5 (Pololike kinase homolog) to the bud neck and Cdc5-dependent Swe1 phosphorylation. Mitotic cyclin (Clb2)-bound Cdc28 (Cdk1 homolog) directly phosphorylated Swe1 and this modification served as a priming step to promote subsequent Cdc5-dependent Swe1 hyperphosphorylation and degradation. Clb2-Cdc28 also facilitated Cdc5 localization to the bud neck through the enhanced interaction between the Clb2-Cdc28-phosphorylated Swe1 and the polo-box domain of Cdc5. We propose that the concerted action of Cdc28/Cdk1 and Cdc5/Polo on their common substrates is an evolutionarily conserved mechanism that is crucial for effectively triggering mitotic entry and other critical mitotic events.

The non-catechol, selective dopamine D2-agonist compound 3H-205–502 was used to localize dopamine D2 receptors by autoradiography after in vitro labeling of brain sections. The characteristics of the binding of this ligand to tissue sections were those expected from the labeling of dopamine D2 receptors. The binding of 3H-205–502 was inhibited selectively and stereospecifically by dopamine D2 agents but not by dopamine D1 compounds. The autoradiographic localization of 3H-205–502 binding sites showed high densities of dopamine D2 receptors in areas such as the glomerular layer of the olfactory bulb, the nucleus accumbens, caudate-putamen, olfactory tubercle, the lateral septum, and the islands of Calleja. Besides these dopamine-innervated areas the substantia nigra and the ventral tegmental area also showed important receptor densities. Other areas where dopamine D2 receptor binding was found were the stratum lacunosum-moleculare of the hippocampus, bands of labeling in the molecular layer of the 9th and 10th lobules of the cerebellum, and several components of the visual system. This distribution presents similarities and differences with previously reported distributions of dopamine D2 receptors visualized autoradiographically using 3H-labeled agonists and antagonists. In view of the high affinity, guanine nucleotide insensitivity, and dopamine D2 selectivity of this agonist ligand, it is suggested that dopamine D2 receptors exist in different states in different areas. 3H-205–502 appears to be a new and useful tool for the study of dopamine D2 receptors.

Airway inflammation is thought to play a major role in the pathogenesis of bronchial asthma. The precise role of individual inflammatory cells, mediator and asthma related genes in allergic lung diseases is not completely understood. The uteroglobin-related protein (UGRP) 1 was proposed to be an asthma candidate gene and play a role in regulating lung inflammation, however its precise function in the airways remains obscure. In this investigation, we used a mouse model of allergic airway inflammation to establish a relationship between UGRP 1 and IL-5 in airway inflammation. Ovalbumin (OVA) challenged mice demonstrate eosinophilia in airway tissues and high levels of IL-5 in bronchoalveolar lavage (BAL) fluid analogous to that found in bronchial asthma. Interestingly, these "OVA-challenged" mice show down-regulation of Ugrp1 expression as compared with the control group. Regression analysis further demonstrates a significant negative correlation between Ugrp1 mRNA expression in the lung and IL-5 levels in BAL fluid with r = 0.948 and P < 0.0001 when IL-5 levels were normalized by log transformation. Intranasal instillation of IL-5 to mice revealed an inhibitory effect of IL-5 on the expression of Ugrp1 mRNA. Together, these results indicate an involvement of IL-5 in the down-regulation of Ugrp1 expression in airway inflammation such as allergic asthma disease.

An in vitro autoradiographic technique has been used for the quantitative mapping of calcium antagonist binding sites (CABS) in the rat brain, using the 1,4-dihydropyridines [3H]PN 200-110 and [3H]PY 108-068 as ligands. CABS were distributed throughout the brain in a highly heterogeneous fashion. The highest densities of CABS were observed in the olfactory bulb, hippocampus and parts of the amygdala. The neocortex was also rich in CABS. The basal ganglia, thalamus and hypothalamus presented intermediate levels of CABS while low densities of sites were seen in areas such as the cerebellum, pons and white matter tracts. The distributions of CABS in brain does not correlate with indexes of brain blood flow, regional glucose utilization or the distributions of receptor binding sites for drugs and neurotransmitters analyzed until now. No correlation exists between CABS distribution and that of any neurotransmitter or brain enzyme described so far. The heterogeneous distributions of CABS is suggestive of a neuronal localization, an idea supported by lesion experiments.