Two Sec13p homologs, AtSec13A and AtSec13B, redundantly contribute to the formation of COPII transport vesicles in Arabidopsis thaliana

COPII vesicles mediate protein transport from ER to Golgi. Sec13 makes up lattice structure with Sec31 to form COPII vesicles. We analyzed expression of two Arabidopsis thaliana Sec13 homologs, AtSec13A and AtSec13B. AtSec13A was expressed in most parts of seedlings, while AtSec13B was partially expressed. Interaction of AtSec13A or AtSec13B with Sec31 homolog was demonstrated by bimolecular fluorescence complementation (BiFC).     

The Mek1 phosphorylation cascade plays a role in meiotic recombination of Schizosaccharomyces pombe

Mek1 is a Chk2/Rad53/Cds1-related protein kinase that is required for proper meiotic progression of Schizosaccharomyces pombe. However, the molecular mechanisms of Mek1 regulation and Mek1 phosphorylation targets are unclear. Here, we report that Mek1 is phosphorylated at serine-12 (S12), S14 and threonine-15 (T15) by Rad3 (ATR) and/or Tel1 (ATM) kinases that are activated by meiotic programmed double-strand breaks (DSBs). Mutations of these sites by alanine replacement caused abnormal meiotic progression and recombination rates. Phosphorylation of these sites triggers autophosphorylation of Mek1; indeed, alanine replacement mutations of Mek1-T318 and -T322 residues in the activation loop of Mek1 reduced Mek1 kinase activity and meiotic recombination rates. Substrates of Mek1 include Mus81-T275, Rdh54-T6 and Rdh54-T673. Mus81-T275 is known to regulate the Mus81 function in DNA cleavage, whereas Rdh54-T6A/T673A mutant cells showed abnormal meiotic recombination. Taken together, we conclude that the phosphorylation of Mek1 by Rad3 or Tel1, Mek1 autophosphorylation and Mus81 or Rdh54 phosphorylation by Mek1 regulate meiotic progression in S. pombe.Key words: Mek1, meiotic recombination, phosphorylation, Rdh54, Mus81     

A Low-Dose β1-Blocker in Combination with Milrinone Improves Intracellular Ca2+ Handling in Failing Cardiomyocytes by Inhibition of Milrinone-Induced Diastolic Ca2+ Leakage from the Sarcoplasmic Reticulum

Objectives

The purpose of this study was to investigate whether adding a low-dose β1-blocker to milrinone improves cardiac function in failing cardiomyocytes and the underlying cardioprotective mechanism.

Background

The molecular mechanism underlying how the combination of low-dose β1-blocker and milrinone affects intracellular Ca²⁺ handling in heart failure remains unclear.

Methods

We investigated the effect of milrinone plus landiolol on intracellular Ca²⁺ transient (CaT), cell shortening (CS), the frequency of diastolic Ca²⁺ sparks (CaSF), and sarcoplasmic reticulum Ca²⁺ concentration ({Ca²⁺}_SR) in normal and failing canine cardiomyocytes and used immunoblotting to determine the phosphorylation level of ryanodine receptor (RyR2) and phospholamban (PLB).

Results

In failing cardiomyocytes, CaSF significantly increased, and peak CaT and CS markedly decreased compared with normal myocytes. Administration of milrinone alone slightly increased peak CaT and CS, while CaSF greatly increased with a slight increase in {Ca²⁺}_SR. Co-administration of β1-blocker landiolol to failing cardiomyocytes at a dose that does not inhibit cardiomyocyte function significantly decreased CaSF with a further increase in {Ca²⁺}_SR, and peak CaT and CS improved compared with milrinone alone. Landiolol suppressed the hyperphosphorylation of RyR2 (Ser2808) in failing cardiomyocytes but had no effect on levels of phosphorylated PLB (Ser16 and Thr17). Low-dose landiolol significantly inhibited the alternans of CaT and CS under a fixed pacing rate (0.5 Hz) in failing cardiomyocytes.

Conclusion

A low-dose β1-blocker in combination with milrinone improved cardiac function in failing cardiomyocytes, apparently by inhibiting the phosphorylation of RyR2, not PLB, and subsequent diastolic Ca²⁺ leak.     

The Influence of Measurement Parameters on the Specific Rotation of Amino Acids

The effects of solute and hydrochloric acid concentrations on optical rotation were studied using 20 naturally occuring amino acids.

There appeared to be no common factor among the amino acids as far as the inclination of optical rotation was concerned. Lutz-Jirgenson’s rule could be applied to few amino acids in the cationic form. Therefore, in the determination of the optical rotation, the concentration of the solute, nature of solvent and temperature must be rigorously controlled. The optical conditions of measurement and the specific rotation of 20 amino acids were recommended based on this work.     

Aromatase inhibitor and 17alpha-methyltestosterone cause sex-reversal from genetical females to phenotypic males and suppression of P450 aromatase gene expression in Japanese flounder (Paralichthys olivaceus)

The sex of Japanese flounder (Paralichthys olivaceus) is easily altered by water temperature or sex steroid hormone treatment during the period of sex determination. We have previously shown that rearing the genetically female larvae at high water temperature caused the suppression of P450 aromatase (P450arom) gene expression in the gonad and phenotypic sex-reversal of the individuals to males (Kitano et al. 1999. J Mol Endocrinol 23:167-176). In the present study, we show that treatment of genetically female larvae with fadrozole (aromatase inhibitor) or 17alpha-methyltestosterone induces sex-reversal as well as suppression of P450arom gene expression. The effect of fadrozole was counteracted by co-administration of estradiol-17beta. Effective periods for fadrozole treatment to induce sex-reversal were similar to those for high water temperature treatment. RT-PCR did not detect P450arom mRNA in gonad of the sex-reversed, phenotypic males. These results indicate that sex-reversal of the genetically female larvae by aromatase inhibitor (or 17alpha-methyltestosterone) may be due to the suppression of P450arom gene expression and the resultant decrease in the amount of estrogen.     

A genomewide survey of developmentally relevant genes in Ciona intestinalis. VI. Genes for Wnt,TGFbeta, Hedgehog and JAK/STAT signaling pathways

Cell-cell interactions play important roles in a variety of developmental processes, and therefore molecules involved in the signaling pathways have been studied extensively. Recently, the draft genome sequence of the basal chordate, Ciona intestinalis, was determined. Here we annotated genes for the signaling pathways of Wnt, transforming growth factor beta (TGFbeta), Hedgehog, and JAK/STAT in the genome of Ciona intestinalis. The Ciona genome contains ten wnt genes, six frizzled genes, four sFRP genes, ten TGFbeta family member genes, five TGFbeta-receptor genes, and five Smad genes; most of the genes were found with less redundancy than in vertebrate genomes. The other genes in the signaling pathways are present as a single copy in the Ciona genome. In addition, all of the identified genes for the signaling pathway, except for a few genes, have EST evidence, and their cDNAs are available from the Ciona intestinalis gene collection. Therefore, Ciona intestinalis may provide an experimental system for exploring the basic genetic cascade associated with the signaling pathways in chordates.     

Imprint cytology of epithelioid angiomyolipoma in a patient with tuberous sclerosis. A case report

BACKGROUND: Angiomyolipoma composed predominantly of epithelioid cells has been referred to as epithelioid angiomyolipoma. As this subtype shows considerable cellular atypia, it may be erroneously diagnosed as malignant epithelioid tumor, such as renal cell carcinoma and hepatocellular carcinoma. So far, only one report describing the cytologic findings of epithelioid angiomyolipoma has been documented, and epithelioid angiomyolipoma occurring in the peritoneal cavity has not been reported. CASE: Eleven years after resection of a renal epithelioid angiomyolipoma in a 34-year-old male with tuberous sclerosis, a tumor appeared in the peritoneal cavity and three masses in the liver. The intraoperative smears imprinted from part of the peritoneal mass revealed many large, atypical cells. The well-preserved atypical cells showed abundant, round to polyhedral, granular cytoplasm. Bizarre, giant nuclei with hyperchromasia and huge nucleoli were occasionally seen. Intranuclear cytoplasmic inclusions and mitotic figures were occasionally observed. As the epithelioid cells were markedly pleomorphic, we could not rule out hepatocellular carcinoma, cytologically and histologically, in the intraoperative consultation. In permanent sections the tumor was composed predominantly of epithelioid cells showing an alveolar pattern or sheetlike arrangement. Mitotic counts were zero to one per 10 high-power fields. Immunohistochemically, the epithelioid tumor cells were positive for vimentin, alpha-smooth muscle actin and HMB-45, consistent with epithelioid angiomyolipoma. MIB-1-labeling index was 1.6%. CONCLUSION: When one sees atypical epithelioid tumor cells in a tuberous sclerosis patient during an intraoperative consultation, one must consider epithelioid angiomyolipoma.