LAMMER Kinase Modulates Cell Cycle by Phosphorylating the MBF Repressor, Yox1, in Schizosaccharomyces pombe

Lkh1, a LAMMER kinase homolog in the fission yeast Schizosaccharomyces pombe, acts as a negative regulator of filamentous growth and flocculation. It is also involved in the response to oxidative stress. The lkh1-deletion mutant displays slower cell growth, shorter cell size, and abnormal DNA content compared to the wild type. These phenotypes suggest that Lkh1 controls cell size and cell cycle progression. When we performed microarray analysis using the lkh1-deletion mutant, we found that only four of the up-regulated genes in the lkh1-deletion were associated with the cell cycle. Interestingly, all of these genes are regu lated by the Mlu1 cell cycle box binding factor (MBF), which is a transcription complex responsible for regulating the expression of cell cycle genes during the G1/S phase. Transcription analyses of the MBF-dependent cell-cycle genes, including negative feedback regulators, confirmed the up-regulation of these genes by the deletion of lkh1. Pull-down assay confirmed the interaction between Lkh1 and Yox1, which is a negative feedback regu lator of MBF. This result supports the involvement of LAMMER kinase in cell cycle regulation by modulating MBF activity. In vitro kinase assay and NetPhosK 2.0 analysis with the Yox1 T40,41A mutant allele revealed that T40 and T41 residues are the phosphorylation sites mediated by Lkh1. These sites affect the G1/S cell cycle progression of fission yeast by mod ulating the activity of the MBF complex.

LAMMER Kinase Lkh1 Is an Upstream Regulator of Prk1-Mediated Non-Sexual Flocculation in Fission Yeast

The cation-dependent galactose-specific flocculation activity of the Schizosaccharomyces pombe null mutant of lkh1⁺, the gene encoding LAMMER kinase homolog, has previously been reported by our group. Here, we show that disruption of prk1⁺, another flocculation associated regulatory kinase encoding gene, also resulted in cation-dependent galactose-specific flocculation. Deletion of prk1 increased the flocculation phenotype of the lkh1⁺ null mutant and its overexpression reversed the flocculation of cells caused by lkh1 deletion. Transcript levels of prk1⁺ were also decreased by lkh1⁺ deletion. Cumulatively, these results indicate that Lkh1 is one of the negative regulators acting upstream of Prk1, regulating non-sexual flocculation in fission yeast.

Depletion of epsilon-COP in the COPI Vesicular Coat Reduces Cleistothecium Production in Aspergillus nidulans

We have previously isolated epsilon-COP, the alpha-COP interactor in COPI of Aspergillus nidulans, by yeast two-hybrid screening. To understand the function of epsilon-COP, the aneA+ gene for epsilon-COP/AneA was deleted by homologous recombination using a gene-specific disruption cassette. Deletion of the epsilon-COP gene showed no detectable changes in vegetative growth or asexual development, but resulted in decrease in the production of the fruiting body, cleistothecium, under conditions favorable for sexual development. Unlike in the budding yeast Saccharomyces cerevisiae, in A. nidulans, over-expression of epsilon-COP did not rescue the thermo-sensitive growth defect of the alpha-COP mutant at 42degrees C. Together, these data show that epsilon-COP is not essential for viability, but it plays a role in fruiting body formation in A. nidulans.

Role of LAMMER Kinase in Cell Wall Biogenesis during Vegetative Growth of Aspergillus nidulans

Depending on the acquisition of developmental competence, the expression of genes for beta-1,3-glucan synthase and chitin synthase was affected in different ways by Aspergillus nidulans LAMMER kinase. LAMMER kinase deletion, DeltalkhA, led to decrease in beta-1,3-glucan, but increase in chitin content. The DeltalkhA strain was also resistant to nikkomycin Z.

Possible Roles of LAMMER Kinase Lkh1 in Fission Yeast by Comparative Proteome Analysis

To investigate the possible roles of LAMMER kinase homologue, Lkh1, in Schizosaccharomyces pombe, whole proteins were extracted from wild type and lkh1-deletion mutant cells and subjected to polyacrylamide gel electrophoresis. Differentially expressed proteins were identified by tandem mass spectrometry (MS/MS) and were compared with a protein database. In whole-cell extracts, 10 proteins were up-regulated and 9 proteins were down-regulated in the mutant. In extracellular preparations, 6 proteins were up-regulated in the lkh1 + null mutant and 4 proteins successfully identified: glycolipid anchored surface precursor, beta-glucosidase (Psu1), cell surface protein, glucan 1,3-beta-glucosidase (Bgl2), and exo-1,3 beta-glucanase (Exg1). These results suggest that Lkh1 is involved in regulating cell wall assembly.

Deletion of GBG1/AYR1 Alters Cell Wall Biogenesis in Saccharomyces cerevisiae

We identified a gene for beta-1,3-glucan synthesis (GBG1), a nonessential gene whose disruption alters cell wall synthesis enzyme activities and cell wall composition. This gene was cloned by functional complementation of defects in beta-1,3-glucan synthase activity of the the previously isolated Saccharomyces cerevisiae mutant LP0353, which displays a number of cell wall defects at restrictive temperature. Disruption of the GBG1 gene did not affect cell viability or growth rate, but did cause alterations in cell wall synthesis enzyme activities: reduction of beta-1,3-glucan synthase and chitin synthase III activities as well as increased chitin synthase I and II activities. GBG1 disruption also showed altered cell wall composition as well as susceptibility toward cell wall inhibitors such as Zymolyase, Calcofluor white, and Nikkomycin Z. These results indicate that GBG1 plays a role in cell wall biogenesis in S. cerevisiae

Genomic Organization of ancop Gene for alpha-COP Homolog from Aspergillus nidulans

We have cloned a alpha-COP homolog, ancop, from Aspergillus nidulans by colony hybridization of chromosome specific library using alpha-COP homologous fragment as a probe. The probe DNA was amplified with degenerated primers designed by comparison of conserved region of the amino acid sequences of Saccharomyces cerevisiae alpha-COP, Homo sapiens HEP-COP, and Drosophila melanogaster alpha-COP. Full length cDNA clone was also amplified by RT-PCR. Comparison of genomic DNA sequence with cDNA sequence obtained by RT-PCR revealed 7 introns. Amino acid sequence similarity search of the anCop with other alpha-COPs gave an overall identity of 52% with S. cerevisiae, 47% with human and bovine, 45% with Drosophila and Arabidopsis . In upstream region from the transcription start site, a putative TATA and CAAT motif were also identified.

Antihypertensive Effect of Debrisoquin Sulfate in the Treatment of Hypertension

Authors observed the antihypertensive effect of debrisoquin sulfate in 35 cases of essential hypertension and following results were obtained. 1) Results of short term control of blood pressure with debrisquin in 35 hypertensive patients revealed good control in 74.3%, fair in 14.3%, poor in 5.7% and failure in 5.7% of cases. Significant reduction of blood pressure was achieved in 7 of 9 cases of hypertension with addition of hydrochlorthiazide to debrisoquin. 2) During long term therapy with debrisoquin (duration of average 3.9 months), good control cases were slightly reduced(good in 58.6%, fair in 24.1%, poor in 6.9%, failure in 10.3%). But average effective dose of debriioquin was not increased significantly. 3) Antihypertensive effect of debrisoquin was slightly reduced in the cases of severe hypertension, hypertension of over 10 years duration and complication of cerebrovascular accident. 4) The side effects during treatment with debrisoquin were dizziness in 31.4%, headache in 11.4%, dry mouth, blurred vision, general weakness, insomnia in 8.6% respectively. There were no side effects in 48.6% of cases.

Clinical Studies on Idiopathic Myocardiopathy

Twenty-two cases of idiopathic myocardiopathy were observed during the period of 1962 to 1971 and follow up clinical study was made in 5 cases. The criteria of diagnosis was based mainly on exclusive diagnosis in etiology unknown marked cardiomegaly. 1) Male and female ratio of idiopathic myocardiopathy was 1.1:1 and age of onset were distributed from first decade to fifth decade with similar number of cases. 2) Cardinal symptoms were dyspnea, palpitation, chest pain and cough. Common physical findings were protodiastolic gallop (in 2 cases), moist rales (in 3 cases) and hepatomegaly(in 3 cases). 3) Laboratory findings were normal except elevated T.T.T. in one case. 4) Electrocardiogram were abnormal in all cases. There were 3 cases of left ventricular hypertrophy, 3 cases of non-specific ST-T changes and one case of first degree A-V block, intraventricular conduction defect, abnormal Q wave and low valtage, respectively. 5) After medical treatment, symptoms were improved in 4 cases but heart size was reduced in only one case and E.C.G. abnormalities were unchanged in all cases.