Polymorphisms of p53 codon 72 and MDM2 promoter 309 and the risk of endometrial cancer

Genetic polymorphisms of p53 and its negative regulator murine double minute 2 homolog (MDM2) have been shown to be closely associated with tumorigenesis in a variety of human cancers. In the present study, single nucleotide polymorphism (SNP) at p53 codon 72 and MDM2 promoter 309 was examined for germline DNA samples from 102 endometrial cancer cases and 95 controls using polymerase chain reaction-based fragment analysis. There were no significant differences in the genotype and allele prevalence between control subjects and endometrial cancer patients for p53 codon 72. The GG genotype frequency of MDM2-SNP309 was statistically higher in endometrial cancer patients than that in normal healthy women when compared with the TG genotype ( P = 0.0088). However, no statistically significant differences were found between the TT and TG or GG genotype frequencies and allele prevalence. Interestingly, the combination of the homozygous Arg/Arg genotype of p53 codon 72 and homozygous GG genotype of MDM2 SNP309 polymorphisms was significantly associated with the risk of endometrial cancer (odds ratio = 3.28, 95% confidence interval = 1.13 to 9.53, P = 0.0212). The homozygous variants of wild p53 codon 72 and mutant MDM2 promoter 309 may cooperatively increase the risk of endometrial cancer in a Japanese population.     

Changes in sleep quality of athletes under normobaric hypoxia equivalent to 2,000-m altitude: a polysomnographic study.

This study evaluated the sleep quality of athletes in normobaric hypoxia at a simulated altitude of 2,000 m. Eight male athletes slept in normoxic condition (NC) and hypoxic conditions equivalent to those at 2,000-m altitude (HC). Polysomnographic recordings of sleep included the electroencephalogram (EEG), electrooculogram, chin surface electromyogram, and electrocardiogram. Thoracic and abdominal motion, nasal and oral airflow, and arterial blood oxygen saturation (Sa(O(2))) were also recorded. Standard visual sleep stage scoring and fast Fourier transformation analyses of the EEG were performed on 30-s epochs. Subjective sleepiness and urinary catecholamines were also monitored. Mean Sa(O(2)) decreased and respiratory disturbances increased with HC. The increase in respiratory disturbances was significant, but the increase was small and subclinical. The duration of slow-wave sleep (stage 3 and 4) and total delta power (<3 Hz) of the all-night non-rapid eye movement sleep EEG decreased for HC compared with NC. Subjective sleepiness and amounts of urinary catecholamines did not differ between the conditions. These results indicate that acute exposure to normobaric hypoxia equivalent to that at 2,000-m altitude decreased slow-wave sleep in athletes, but it did not change subjective sleepiness or amounts of urinary catecholamines.     

A ubiquitin ligase HRD1 promotes the degradation of Pael receptor, a substrate of Parkin

It has been proposed that in autosomal recessive juvenile parkinsonism (AR-JP), a ubiquitin ligase (E3) Parkin, which is involved in endoplasmic reticulum-associated degradation (ERAD), lacks E3 activity. The resulting accumulation of Parkin-associated endothelin receptor-like receptor (Pael-R), a substrate of Parkin, leads to endoplasmic reticulum stress, causing neuronal death. We previously reported that human E3 HRD1 in the endoplasmic reticulum protects against endoplasmic reticulum stress-induced apoptosis. This study shows that HRD1 was expressed in substantia nigra pars compacta (SNC) dopaminergic neurons and interacted with Pael-R through the HRD1 proline-rich region, promoting the ubiquitylation and degradation of Pael-R. Furthermore, the disruption of endogenous HRD1 by small interfering RNA (siRNA) induced Pael-R accumulation and caspase-3 activation. We also found that ATF6 overexpression, which induced HRD1, accelerated and caused Pael-R degradation; the suppression of HRD1 expression by siRNA partially prevents this degradation. These results suggest that in addition to Parkin, HRD1 is also involved in the degradation of Pael-R.     

Purification and characterization of Escherichia coli heat-stable enterotoxin II.

Escherichia coli heat-stable enterotoxin II (STII) was purified to homogeneity by successive column chromatographies from the culture supernatant of a strain harboring the plasmid encoding the STII gene. The purified STII evoked a secretory response in the suckling mouse assay and ligated rat intestinal loop assay in the presence of protease inhibitor, but the response was not observed in the absence of the inhibitor. Analyses of the peptide by the Edman degradation method and fast atom bombardment mass spectrometry revealed that purified STII is composed of 48 amino acid residues and that its amino acid sequence was identical to the 48 carboxy-terminal amino acids of STII predicted from the DNA sequence (C. H. Lee, S. L. Mosely, H. W. Moon, S. C. Whipp, C. L. Gyles, and M. So, Infect. Immun. 42:264-268, 1983). STII has four cysteine residues which form two intramolecular disulfide bonds. Two disulfide bonds were determined to be formed between Cys-10-Cys-48 and Cys-21-Cys-36 by analyzing tryptic hydrolysates of STII.     

Impaired autophagy by soluble endoglin,under physiological hypoxia in early pregnant period,is involved in poor placentation in preeclampsia

In early pregnancy, trophoblasts and the fetus experience hypoxic and low-nutrient conditions; nevertheless, trophoblasts invade the uterine myometrium up to one third of its depth and migrate along the lumina of spiral arterioles, replacing the maternal endothelial lining. Here, we showed that autophagy, an intracellular bulk degradation system, occurred in extravillous trophoblast (EVT) cells under hypoxia in vitro and in vivo. An enhancement of autophagy was observed in EVTs in early placental tissues, which suffer from physiological hypoxia. The invasion and vascular remodeling under hypoxia were significantly reduced in autophagy-deficient EVT cells compared with wild-type EVT cells. Interestingly, soluble endoglin (sENG), which increased in sera in preeclamptic cases, suppressed EVT invasion by inhibiting autophagy. The sENG-inhibited EVT invasion was recovered by TGFB1 treatment in a dose-dependent manner. A high dose of sENG inhibited the vascular construction by EVT cells and human umbilical vein endothelial cells (HUVECs), meanwhile a low dose of sENG inhibited the replacement of HUVECs by EVT cells. A protein selectively degraded by autophagy, SQSTM1, accumulated in EVT cells in preeclamptic placental biopsy samples showing impaired autophagy. This is the first report showing that impaired autophagy in EVT contributes to the pathophysiology of preeclampsia.     

Modulatory Action of Taurine on the Release of GABA in Cerebellar Slices of the Guinea Pig

Abstract: For the purpose of demonstrating the action of taurine as a neuromodulator in addition to its suggested neurotransmitter function, the effects of taurine and muscimol on the depolarization-induced Ca-dependent release of [³H]γ-aminobutyric acid (pH]GABA) and l -[³H]glutamate in cerebellar slices from guinea pigs were investigated. The release of [³H]GABA was found to be greatly decreased by a GABA agonist, muscimol, and by taurine, but not by glycine. The release of l -[³H]glutamate was little affected by taurine. The release of [³H]GABA was enhanced by bicuculline and strychnine, but not by picrotoxin, and the suppressive action of muscimol on the GABA release was antagonized by bicuculline, picrotoxin, and strychnine, suggesting the possible existence of presynaptic autoreceptors for GABA in the cerebellum. The suppressive action of taurine on the release of [³H]GABA, on the other hand, was blocked only by bicuculline. These results suggest that taurine reduced the release of [³H]GABA from cerebellar slices by acting on the GABA autoreceptors or, more likely, on other types of receptors that are sensitive to bicuculline. As a possible mechanism for this modulatory action of taurine, the blockade by this amino acid of the influx of Ca²⁺ into cerebellar tissues was tentatively suggested.     

Macrophage chemotactic factor (MCF) produced by a human T cell hybridoma clone

A human T cell hybridoma clone, D6-18, producing high levels of macrophage chemotactic factor (MCF) was established by the emetine-actinomycin D selection method. MCF was found to be present not only in the culture medium but also in the cell lysate of D6-18 cells. The secretion of the MCF from D6-18 cells was effectively inhibited by disodium cromoglycate, which is an inhibitor of the degranulation of mast cells, suggesting that MCF is stored in granules. The MCF of D6-18 cells was purified from the sonicated cell lysate by ion-exchange chromatographies and high-performance liquid chromatography. The amino acid sequence of the purified MCF was revealed to be WLGREDGSE or WLGRQDGSE. The synthetic peptide WLGREDGSE showed chemotactic activity against guinea pig macrophages and human monocytes at the concentration of about 10(-8) M.     

Cyclooxygenase-2/prostaglandin E2 accelerates the healing of gastric ulcers via EP4 receptors

We examined the involvement of cyclooxygenase (COX)-1 as well as COX-2 in the healing of gastric ulcers and investigated which prostaglandin (PG) EP receptor subtype is responsible for the healing-promoting action of PGE2. Male SD rats and C57BL/6 mice, including wild-type, COX-1(-/-), and COX-2(-/-), were used. Gastric ulcers were produced by thermocauterization under ether anesthesia. Gastric ulcer healing was significantly delayed in both rats and mice by indomethacin and rofecoxib but not SC-560 given for 14 days after ulceration. The impaired healing was also observed in COX-2(-/-) but not COX-1(-/-) mice. Mucosal PGE2 content increased after ulceration, and this response was significantly suppressed by indomethacin and rofecoxib but not SC-560. The delayed healing in mice caused by indomethacin was significantly reversed by the coadministration of 11-deoxy-PGE1 (EP3/EP4 agonist) but not other prostanoids, including the EP1, EP2, and EP3 agonists. By contrast, CJ-42794 (selective EP(4) antagonist) significantly delayed the ulcer healing in rats and mice. VEGF expression and angiogenesis were both upregulated in the ulcerated mucosa, and these responses were suppressed by indomethacin, rofocoxib, and CJ-42794. The expression of VEGF in primary rat gastric fibroblasts was increased by PGE2 or AE1-329 (EP4 agonist), and these responses were both attenuated by coadministration of CJ-42794. These results confirmed the importance of COX-2/PGE2 in the healing mechanism of gastric ulcers and further suggested that the healing-promoting action of PGE2 is mediated by the activation of EP4 receptors and is associated with VEGF expression.