Expression level of enzymes related to in situ estrogen synthesis and clinicopathological parameters in breast cancer patients

In order to evaluate the importance of estrogen production in tumor and surrounding tissues, we measured mRNA expression levels of 5 enzymes participating to estrogen synthesis in situ and 4 breast cancer-related proteins in 27 pairs of tumor and non-malignant tissues. Steroid sulfatase (STS) mRNA was more frequently detected in tumor tissues rather than in their non-malignant counterparts. Estrogen sulfotransferase (EST) was constantly expressed with high level not only in tumor tissues but also in their surrounding non-malignant counterparts. In contrast, mRNA expression levels of aromatase, and 17β-hydroxysteroid dehydrogenase type I and II were relatively low and detected only in small proportion of the patients. We also measured the mRNA expression levels of the same nine genes in tumor tissues of 197 breast cancer patients, and analyzed relationship between the mRNA expression level and the clinicopathological parameters. The mRNA expression levels of STS, aromatase and erbB2 in tumor tissues increased as breast cancer progressed. The tumoral mRNA expression levels of STS, estrogen receptor β, and erbB2 in patients with recurrence were higher than those in patients without recurrence. Upregulation of STS expression plays an important role in tumor progression of human breast cancer and is considered to be responsible for estrogen production in tumor and surrounding tissues.     

Phosphorylation and ubiquitination of dynamin-related proteins (AtDRP3A/3B) synergically regulate mitochondrial proliferation during mitosis

The balance between mitochondrial fission and fusion is disrupted during mitosis, but the mechanism governing this phenomenon in plant cells remains enigmatic. Here, we used mitochondrial matrix‐localized Kaede protein (mt‐Kaede) to analyze the dynamics of mitochondrial fission in BY‐2 suspension cells. Analysis of the photoactivatable fluorescence of mt‐Kaede suggested that the fission process is dominant during mitosis. This finding was confirmed by an electron microscopic analysis of the size distribution of mitochondria in BY‐2 suspension cells at various stages. Cellular proteins interacting with Myc‐tagged dynamin‐related protein 3A/3B (AtDRP3A and AtDRP3B) were immunoprecipitated with anti‐Myc antibody‐conjugated beads and subsequently identified by microcapillary liquid chromatography–quadrupole time‐of‐flight mass spectrometry (CapLC Q‐TOF) MS/MS. The identified proteins were broadly associated with cytoskeletal (microtubular), phosphorylation, or ubiquitination functions. Mitotic phosphorylation of AtDRP3A/AtDRP3B and mitochondrial fission at metaphase were inhibited by treatment of the cells with a CdkB/cyclin B inhibitor or a serine/threonine protein kinase inhibitor. The fate of AtDRP3A/3B during the cell cycle was followed by time‐lapse imaging of the fluorescence of Dendra2‐tagged AtDRP3A/3B after green‐to‐red photoconversion; this experiment showed that AtDRP3A/3B is partially degraded during interphase. Additionally, we found that microtubules are involved in mitochondrial fission during mitosis, and that mitochondria movement to daughter cell was limited as early as metaphase. Taken together, these findings suggest that mitotic phosphorylation of AtDRP3A/3B promotes mitochondrial fission during plant cell mitosis, and that AtDRP3A/3B is partially degraded at interphase, providing mechanistic insight into the mitochondrial morphological changes associated with cell‐cycle transitions in BY‐2 suspension cells.     

Biochemical Conservation and Evolution of Germacrene A Oxidase in Asteraceae

Sesquiterpene lactones are characteristic natural products in Asteraceae, which constitutes ∼8% of all plant species. Despite their physiological and pharmaceutical importance, the biochemistry and evolution of sesquiterpene lactones remain unexplored. Here we show that germacrene A oxidase (GAO), evolutionarily conserved in all major subfamilies of Asteraceae, catalyzes three consecutive oxidations of germacrene A to yield germacrene A acid. Furthermore, it is also capable of oxidizing non-natural substrate amorphadiene. Co-expression of lettuce GAO with germacrene synthase in engineered yeast synthesized aberrant products, costic acids and ilicic acid, in an acidic condition. However, cultivation in a neutral condition allowed the de novo synthesis of a single novel compound that was identified as germacrene A acid by gas and liquid chromatography and NMR analyses. To trace the evolutionary lineage of GAO in Asteraceae, homologous genes were further isolated from the representative species of three major subfamilies of Asteraceae (sunflower, chicory, and costus from Asteroideae, Cichorioideae, and Carduoideae, respectively) and also from the phylogenetically basal species, Barnadesia spinosa, from Barnadesioideae. The recombinant GAOs from these genes clearly showed germacrene A oxidase activities, suggesting that GAO activity is widely conserved in Asteraceae including the basal lineage. All GAOs could catalyze the three-step oxidation of non-natural substrate amorphadiene to artemisinic acid, whereas amorphadiene oxidase diverged from GAO displayed negligible activity for germacrene A oxidation. The observed amorphadiene oxidase activity in GAOs suggests that the catalytic plasticity is embedded in ancestral GAO enzymes that may contribute to the chemical and catalytic diversity in nature.     

Phosphorylation and Inactivation of Brain Glycogen Synthase by a Multifunctional Calmodulin-Dependent Protein Kinase

Glycogen synthase was partially purified from canine brain to about 70% purity. The purified enzyme showed differences from the properties of the skeletal muscle enzyme with respect to molecular weights of the holoenzyme and subunit and phosphopeptide mapping. The multifunctional calmodulin-dependent protein kinase from the brain phosphorylated brain glycogen synthase with concomitant inactivation of the enzyme. Although about 1.3 mol of phosphate/mol subunit was maximally incorporated into glycogen synthase, 0.4 mol of phosphate/mol subunit was sufficient for the maximal inactivation of the enzyme. The results indicate that brain glycogen synthase is regulated in a calmodulin-dependent manner similarly to the skeletal muscle enzyme, but that the brain enzyme is different from the skeletal muscle enzyme.     

Binding sites of HeLa cell nuclear proteins on the upstream region of adenovirus type 5 E1A gene.

Twenty one binding sites of HeLa cell nuclear proteins were identified on the upstream region of adenovirus type 5 E1A gene using DNase I footprint assay. The proximal promoter region contained five binding sites that overlapped the cap site, TATA box, TATA-like sequence, CCAAT box, and -100 region relative to the E1A cap site(+1). The -190 region was a potential site for octamer-motif binding proteins, such as NFIII and OBP100. An upstream copy of the E1A enhancer element 1 was the site for a factor (E1A-F) with the binding specificity of XGGAYGT (X = A, C; Y = A, T). E1A-F factor also bound to three other sites, one of which coincided with the distal E1A enhancer element. The distal element also contained a potential site for ATF factor. The adenovirus minimal origin of DNA replication competed for DNA-protein complex formation on the CCAAT and TATA box region and the -190 region, suggesting that these regions interacted with a common or related factor.     

The membrane domain of 3-hydroxy-3-methylglutaryl-coenzyme A reductase confers endoplasmic reticulum localization and sterol-regulated degradation onto beta-galactosidase

A hybrid gene has been constructed consisting of coding sequence for the membrane domain of the endoplasmic reticulum protein 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase linked to the coding sequence for the soluble enzyme Escherichia coli beta-galactosidase. Expression of the hybrid gene in transfected Chinese hamster ovary cells results in the production of a fusion protein (HMGal) which is localized in the endoplasmic reticulum. The fusion protein contains the high-mannose oligosaccharides characteristic of HMG-CoA reductase. Importantly the beta-galactosidase activity of HMGal decreases when low density lipoprotein is added to the culture media. Therefore, the membrane domain of HMG-CoA reductase is sufficient to determine both correct intracellular localization and sterol-regulation of degradation. Mutant fusion proteins which lack 64, 85, or 98 amino acid residues from within the membrane domain of HMG-CoA reductase are found to be localized in the endoplasmic reticulum and to retain beta-galactosidase activity. However, sterol-regulation of degradation is abolished.     

Molecular cloning and expression ofThiobacillus ferrooxidans chromosomal ribulose bisphosphate carboxylase genes inEscherichia coli

The genes coding ford-ribulose-1,5-bisphosphate carboxylase (RuBPCase) from an iron-oxidizing bacterium,Thiobacillus ferrooxidans, were cloned into anEscherichia coli plasmid, pUC18. The recombinant plasmid, termed pTR11, contained a 4.0-kb PstI fragment including the entire coding regions for both large and small subunits of RuBPCase.Escherichia coli carrying pTR11 did not show any CO₂-fixing activity. However, a derivative plasmid with an appropriate deletion, which was placed under the control of atac promoter, conferred ribulose bisphosphate-dependent CO₂-fixing activity on the host cell. Analysis of gel-filtration chromatography of the RuBPCase synthesized inE. coli revealed that it had a hexadecameric form like the native enzyme ofT. ferrooxidans.     

Establishment of a new perchloric acid treatment method to allow determination of the total endotoxin content in human plasma by the limulus test and clinical application.

We established a new method of plasma treatment for the removal of interfering factors in the plasma to allow detection of endotoxin by limulus test. The limulus test used was an endotoxin-specific chromogenic test, the Endospecy test. Perchloric acid (PCA) treatment and centrifugation (PCA method) is usually used to remove interfering factors from plasma, with the precipitate being discarded and the supernatant used to detect endotoxin. As the solubilized precipitates of endotoxin-spiked plasma and some patient plasma were found to contain the Endospecy activity, we have devised a new method assaying endotoxin in both the supernatant and precipitate. This study confirmed that the solubilized precipitate of endotoxin-spiked plasma had Endospecy activity and found that the precipitate had other endotoxin activities, such as lethality in galactosamine-sensitized mice and pyrogenicity in rabbits. We also confirmed that interfering factors were completely removed from plasma samples by this new method. The endotoxin level after the new PCA method was found to be about 8 times higher than that determined after PCA treatment and the new PCA method surpasses the conventional PCA method with regard to the positive rate of endotoxin contents in clinical samples. These results indicate that the new PCA method is superior to the PCA method as a plasma pretreatment method for limulus test.     

Morphological studies of the neuromuscular mechanism shifting from sucking to biting of mice

In order to give a neuroanatomical evidence to the mechanism of shifting from sucking to biting, we investigated in prenatal, newborn and postnatal mice whether there is a time difference in the neurogenesis of the neurons relative to sucking and biting or in the histogenesis of their peripheral effector organs by the HRP labeling technique and electron microscopy. The results obtained are as follows. (1) At birth the facial motoneurons exceed the trigeminal motoneurons in cell area and development. (2) After birth, the trigeminal motoneurons grow rapidly and outstrip the growth of the facial motoneurons at the age of 6 days. (3) Thereafter, the cell area of both neuron types continues to increase gradually. (4) The initial sign of the alpha motor end plates is found in the orbicularis oris muscle innervated by the facial nerve in 17-day-old fetuses, while that of the trigeminal nerve is delayed in the masseter muscle of 18-day-old fetuses. (5) The initial sign of the muscle spindle appears with the sensory terminals in the masseter muscle of 17-day-old fetuses and the fundamental structure of the muscle spindle is formed in 4-day-old youngs. (6) Myelination of the facial nerve begins in 3-day-old youngs, while that of the trigeminal nerve becomes apparent in 4- or 5-day-old youngs. From these bases, it is obvious that the facial nerve elements related to sucking are firstly developed at birth and that the differentiation of the trigeminal nerve elements related to biting is rapidly accelerated after birth.