Calnexin promotes the folding of mutant iduronate 2-sulfatase related to mucopolysaccharidosis type II.

Mucopolysaccharidosis type II (MPS II) is one of the most common mucopolysaccharidoses, which is caused by mutation of the gene encoding iduronate 2-sulfatase (IDS). The loss of function of IDS leads to the accumulation of heparan sulfate and dermatan sulfate of glycosaminoglycans throughout the body, resulting in skeletal deformities, mental retardation, rigid joints, and thick skin. Recently, enzyme replacement therapy has become a common strategy for treating this condition. However, its effectiveness on the central nervous system (CNS) is limited because intravenously administered recombinant IDS (rIDS) cannot pass through the blood brain barrier. Therefore, several methods for delivering rIDS to the CNS, using anti-human transferrin receptor antibody and adeno-associated virus 9, have been explored. To investigate additional approaches for treatment, more cognition about the intracellular dynamics of mutant IDS is essential. We have already found that mutant IDS accumulated in the endoplasmic reticulum (ER) and was degraded by ER-associated degradation (ERAD). Although the dynamics of degradation of mutant IDS was revealed, the molecular mechanism related to the folding of mutant IDS in the ER remained unclear. In this research, we confirmed that mutant IDS retained in the ER would be folded by binding with calnexin (CNX). Thus, knockdown of CNX reduced the translocation of mutant IDS from ER to lysosome and its enzyme activity, indicating that the correct folding of this protein via interaction with CNX ensures its functional activity. These findings reveal the possibility that modifying the interaction of mutant IDS and CNX could contribute to alternative therapeutic strategies for MPS II.

[Gender-dependent Expression of ERß in AEC â ¡ of Fetal Mice Exposed to Arsenic and Estrogen Receptor Antagonist].

OBJECTIVE: To determine the effects of arsenic and estrogen receptor antagonist (ICI182, 780) on the expression of estrogen receptor beta (ERß) in alveolar Ⅱ epithelial cells (AECⅡ) of female and male mice. METHODS: Nineteen or twenty day fetus mice were obtained through caesarean section of ICR mice. Purified AECⅡ cells were separated from the female and male fetus,respectively,and confirmed using immunofluorescence staining. The cells were exposed to sodium arsenite (NaAsO2) at a low,medium,or high dosage determined by MTT and cultured for 24 h. The NaAsO2 (5 µmol/L) exposed cells were compared with those treated (for 24 h) with dimethyl sulfoxide (DMSO) or ICI182, 780 (1×10-4 mol/L). Apoptosis rates of the cells were measured by flow cytometry. Real-time fluorescence quantitative PCR method and Western blot technique were used to detect the expression ofERßmRNA and protein in AECⅡ. RESULTS: Purity of AECⅡ cells reached (87.0±2.5)%. NaAsO2 exposure was set at a concentration of 0.5 (low),1.25 (medium),and 5 (high) µmol/L. The cells exposed to medium and high dosage of NaAsO2 had higher apoptosis rates than the blank controls (P<0.05),without sex differences. Female cells exposed to medium and high dosage of NaAsO2 had higher levels of expressions ofERßmRNA and protein than the blank controls (P<0.05) and male cells exposed to the same dosage of NaAsO2 (P<0.05). No significant differences were found in the expressions ofERßmRNA and protein between the exposed male cells and the blank controls. ICI182, 780 lowered the expression levels ofERßmRNA and protein in the female exposed cells (P<0.01). CONCLUSION: Arsenic exposure increases expressions of AECⅡ's ERß,more so in female cells than in male cells. This can be blocked by estrogen receptor antagonists.

[Gender-dependent expression of ERalpha in arsenic exposed mice offspring's lung tissue].

OBJECTIVE: To observe theexpression variations of estrogen receptor alpha (ERalpha) in different periods of mice offspring and the gender-dependent differences in the lung tissue with parental arsenic exposure. METHODS: Parental female mice were exposed to arsenic by gavage from gestational day 8th to offspring infancy, and offspring were exposed to arsenic by drinking water after infancy. The expression level of ERalpha mRNA and protein in lung tissue of the male and female offspring in different developmental periods and different doses (low, middle, high) of sodium arsenite exposure were detected by real-time PCR and Western blot. RESULTS: ERalpha mRNA expression in female lung tissue was lower than male in embryonic period (P<0.05); ERalpha mRNA expression in female lung tissue was higher than that of male in infant and adult periods (middle dose of infancy P<0.05, middle and high doses of adulthood P<0.05); No statistical significances were observed in embryo, infancy and adulthood control groups. ERalpha mRNA expression in female lung tissue of infancy and adulthood was higher than that in embryonic period (low, middle and high dose groups P<0.05). ERa protein expression in arsenic exposed female lung tissue was higher than that of male in infant and adult periods, it was also increased by compared with corresponding control groups (P<0.05). The expression level of ERalpha protein in exposed adult female and male offspring were higher than that of infancy. CONCLUSION: Arsenic infected during pregnancy can increase the lung tissue's ERalpha expression level of female offspring in infancy and adulthood. This result is significant to elucidate the role of environment pollutants in gender difference of lung cancer's occurrence.

[Oxidative damage of gasoline engine exhausts to rat lung tissues].

OBJECTIVE: To study the effects of extracts of condensate, particulates and semivolatile organic compounds from gasoline engine exhaust on DNA damage, 8-oxoguanine DNA glycosylase-1 (OGG1) expression, and changes of ultra-structures in lungs of rats. METHODS: Organic extracts of gasoline engine exhaust (GEE) was intratrachealy instilled into rat lungs at 0, 5.6, 16.7, and 50.0 L/kg body weight, respectively, once a week for a month. The single DNA strand break was measured by comet assay. The OGG1 was determined using immunohistochemistry method. The ultrastructure of lung cells was observed with electronic microscope. RESULTS: The rates of tailed cells detected by the comet assay increased significantly when the rats were exposed to 16.7 and 50.0 L/kg of GEE compared with those exposed to solvent only (P < 0.05). However, the tail length did not differ significantly between the groups. Similarly, exposure to 16.7 and 50.0 L/kg of GEE led to increased OGG1 significantly. Significant changes of mitochondria in type I and II alveolar cells as well as respiratory bronchiole epithelial cells were observed, which included decrease of numbers, pyknosis and swelling. CONCLUSION: Gasoline engine exhausts induce single DNA strand break, increase OGG1 expression, decrease numbers of mitochondria, and destroy ultrastructures of mitochondria in various lung cells of rats.

Impairment of the spatial learning and memory induced by learned helplessness and chronic mild stress.

Increasing evidences indicate the concurrence and interrelationship of depression and cognitive impairments. The present study was undertaken to investigate the effects of two depressive animal models, learned helplessness (LH) and chronic mild stress (CMS), on the cognitive functions of mice in the Morris water maze task. Our results demonstrated that both LH and CMS significantly decreased the cognitive performance of stressed mice in the water maze task. The escaping latency to the platform was prolonged and the probe test percentage in the platform quadrant was reduced. These two models also increased the plasma corticosterone concentration and decreased the brain derived neurotrophic factor (BDNF) and cAMP-response element-biding protein (CREB) messenger ribonucleic acid (mRNA) levels in hippocampus, which might cause the spatial cognition deficits. Repeated treatment with antidepressant drugs, imipramine (Imi) and fluoxetine (Flu), significantly reduced the plasma corticosterone concentration and enhanced the BDNF and CREB levels. Furthermore, antidepressant treated animals showed an ameliorated cognitive performance compared with the vehicle treated stressed animals. These data suggest that both LH and CMS impair the spatial cognitive function and repeated treatment with antidepressant drugs decreases the prevalence of cognitive impairments induced by these two animal models. Those might in part be attributed to the reduced plasma corticosterone and enhanced hippocampal BDNF and CREB expressions. This study provided a better understanding of molecular mechanisms underlying interactions of depression and cognitive impairments, although animal models used in this study can mimic only some aspects of depression or cognition of human.