Retinal degenerative diseases (RDs) are a group of inherited diseases characterized by the loss of photoreceptor cells. Selective photoreceptor loss can be induced in mice by an intraperitoneal injection of N‐methyl‐N‐nitrosourea (MNU) and, because of its selectivity, this model is widely used to study the mechanism of RDs. Although it is known that calcium‐calpain activation and lipid peroxidation are involved in the initiation of cell death, the precise mechanisms of this process remain unknown. Heat shock protein 70 (HSP70) has been shown to function as a chaperone molecule to protect cells against environmental and physiological stresses. In this study, we investigated the role of HSP70 on photoreceptor cell death in mice. HSP70 induction by valproic acid, a histone deacetylase inhibitor, attenuated the photoreceptor cell death by MNU through inhibition of apoptotic caspase signals. Furthermore, HSP70 itself was rapidly and calpain‐dependently cleaved after MNU treatment. Therefore, HSP70 induction by valproic acid was dually effective against MNU‐induced photoreceptor cell loss as a result of its anti‐apoptotic actions and its ability to prevent HSP70 degradation. These findings might help lead us to a better understanding of the pathogenic mechanism of RDs.
Retinitis pigmentosa (RP) is a group of inherited neurodegenerative diseases characterized by the loss of photoreceptor cells through apoptosis. N‐methyl‐N‐nitrosourea (MNU) is an alkylating toxicant that induces photoreceptor cell death resembling hereditary RP. This study aimed to investigate the role of nuclear factor κB (NF‐κB) in MNU‐induced photoreceptor degeneration. Adult rats received a single intraperitoneal injection of MNU (60 mg/kg bodyweight). Hematoxylin and eosin staining demonstrated progressive outer nuclear layer (ONL) loss after MNU treatment. Transmission electron microscopy revealed nuclear pyknosis, chromatin margination in the photoreceptors, increased secondary lysosomes, and lobulated retinal‐pigmented epithelial cells in MNU‐treated rats. Numerous photoreceptor cells in the ONL showed positive TUNEL staining and apoptosis rate peaked at 24 hours. Enhanced depth imaging spectral‐domain optical coherence tomography showed ONL thinning and decreased choroid thickness. Electroretinograms showed decreased A wave amplitude that predominated in scotopic conditions. Western blot analysis showed that nuclear IκBα level increased, whereas nuclear NF‐κB p65 decreased significantly in the retinas of MNU‐treated rats. These findings indicate that MNU leads to selective photoreceptor degradation, and this is associated with the inhibition of NF‐κB activation. 相似文献
The N‐acylethanolamines (NAEs) exert important behavioral, physiological, and immunological effects through actions at cannabinoid and other receptors. We measured concentrations of three NAEs, the Km and Vmax for fatty acid amide hydrolysis (FAAH), FAAH protein and FAAH mRNA in prefrontal cortex, hippocampus, hypothalamus, amygdala, striatum, and cerebellum at 4 h intervals, starting at 03:00. Significant differences in N‐arachidonylethanolamine contents among the times examined occur in the prefrontal cortex (PFC), hippocampus, hypothalamus, and striatum. N‐Oleoylethanolamine concentrations exhibit large fluctuations over the day in the cerebellum, including a threefold decrease between 19:00 and 23:00. N‐Palmitoylethanolamine and N‐oleoylethanolamine were significantly, positively correlated in all regions examined except the hypothalamus. FAAH Km values are significantly affected by time of day in PFC, hippocampus and amygdala and FAAH Vmax values are significantly affected in PFC, hippocampus and cerebellum. However, correlational data indicate that FAAH does not play a primary role in the circadian regulation of the NAE concentrations. FAAH protein expression is not significantly different among the harvest times in any brain region examined. Concentrations of 2‐arachidonoylglycerol are significantly affected by time of harvest in the striatum and cerebellum, but not in other brain regions. Together, these data indicate that the NAEs exhibit diverse patterns of change with time of day that are likely the result of alterations in biosynthesis, and support the hypothesis that N‐arachidonylethanolamine is a tonic activator of cannabinoid receptor signaling.
The N‐end rule denotes the relationship between the identity of the amino‐terminal residue of a protein and its in vivo half‐life. Since its discovery in 1986, the N‐end rule has generally been described by a defined set of rules for determining whether an amino‐terminal residue is stabilizing or not. However, recent studies are revealing that this N‐end rule (or N‐degron concept) is less straightforward than previously appreciated. For instance, it is unveiled that N‐terminal acetylation of N‐terminal residues may create a degradation signal (Ac‐degron) that promotes the degradation of target proteins. A recent high‐throughput dissection of degrons in yeast proteins amino termini intriguingly suggested that the hydrophobicity of amino‐terminal residues—but not the N‐terminal acetylation status—may be the indispensable feature of amino‐terminal degrons. Herein, these recent advances in N‐terminal acetylation and the complexity of N‐terminal degradation signals in the context of the N‐degron pathway are analyzed. 相似文献
Glucose‐6‐phosphate dehydrogenase (G6PD) and 6‐phosphogluconate dehydrogenase (6PGD) play an important function in various biochemical processes as they generate reducing power of the cell. Thus, metabolic reprogramming of reduced nicotinamide adenine dinucleotide phosphate (NADPH) homeostasis is reported to be a vital step in cancer progression as well as in combinational therapeutic approaches. In this study, N‐benzoylindoles 9a‐ ‐ 9d , which form the main framework of many natural indole derivatives such as indomethacin and N‐benzoylindoylbarbituric acid, were synthesized through three easy and effective steps as an in vitro inhibitor effect of G6PD and 6PGD. The N‐benzoylindoles inhibited the enzymatic activity with IC50 in the range of 3.391505 μM for G6PD and 2.19–990 μM for 6PGD. 相似文献
BACKGROUND: N‐methyl‐2‐pyrrolidone (NMP) is a solvent used in the petrochemical, and electronic industries, in pesticides production, veterinary drugs, and paint removers. The aim of study was to evaluate the relationship between the dose of NMP given orally and its effect on fertility in female rats and early development of their progeny. METHODS: Females were exposed by gavage 5 days/week to NMP at 150, 450, or 1000 mg/kg/day 2 weeks before mating, during mating, gestation, and lactation. On the first postnatal day (PND 1), the live and dead pups were counted, weighed, and gender was determined. On PND 4, the litters were culled to eight animals each and balanced for gender. Young animals were observed during 3 weeks after birth. RESULTS AND CONCLUSION: Fertility index did not significantly differ in the control and the group exposed at 150 mg/kg/day but it was significantly lower in the groups exposed at 450 or 1000 mg/kg/day. The number of live pups in the group exposed to the highest dose was significantly lower and the number of stillbirths in litters was significantly greater. Survival of the pups from all exposed groups during the 3 weeks after birth was significantly lower than the control animals. The results of our study indicate that intragastric exposure of female rats to NMP before pregnancy during gestation causes significant impairment in female fertility and intrauterine mortality rates. At lower doses, toxic or slightly toxic to the mothers, this substance causes decrease in viability and physical development of progeny. 相似文献
A liquid–liquid extraction resolution of 4‐chloro‐mandelic acid (4‐ClMA) was studied by using 2‐chloro‐N‐carbobenzyloxy‐L‐amino acid (2‐Cl‐Z‐AA) as a chiral extractant. Important factors affecting the extraction efficiency were investigated, including the type of chiral extractant, pH value of aqueous phase, initial concentration of chiral extractant in organic phase, initial concentration of 4‐ClMA in aqueous phase, and resolution temperature. It was observed that the concentration of (R)‐4‐ClMA was much higher than that of (S)‐4‐ClMA in organic phase due to a higher stability of the complex formed between (R)‐4‐ClMA and 2‐Cl‐Z‐AA. A separation factor (α) of 3.05 was obtained at 0.02 mol/L 2‐Cl‐Z‐Valine dissolved in dichloromethane, pH of 2.0, concentration of 4‐ClMA of 0.11 mmol/Land T of 296.7K. 相似文献
The N‐end rule pathway is conserved from bacteria to man and determines the half‐life of a protein based on its N‐terminal amino acid. In Escherichia coli, model substrates bearing an N‐degron are recognised by ClpS and degraded by ClpAP in an ATP‐dependent manner. Here, we report the isolation of 23 ClpS‐interacting proteins from E. coli. Our data show that at least one of these interacting proteins—putrescine aminotransferase (PATase)—is post‐translationally modified to generate a primary N‐degron. Remarkably, the N‐terminal modification of PATase is generated by a new specificity of leucyl/phenylalanyl‐tRNA‐protein transferase (LFTR), in which various combinations of primary destabilising residues (Leu and Phe) are attached to the N‐terminal Met. This modification (of PATase), by LFTR, is essential not only for its recognition by ClpS, but also determines the stability of the protein in vivo. Thus, the N‐end rule pathway, through the ClpAPS‐mediated turnover of PATase may have an important function in putrescine homeostasis. In addition, we have identified a new element within the N‐degron, which is required for substrate delivery to ClpA. 相似文献
N‐acetylneuraminic acid (NeuAc) is a common sialic acid that has a wide range of applications in nutraceuticals and pharmaceuticals. However, low production efficiency and high environmental pollution associated with traditional extraction and chemical synthesis methods constrain the supply of NeuAc. Here, a biological approach is developed for food‐grade NeuAc production via whole‐cell biocatalysis by the generally regarded as safe (GRAS) bacterium Bacillus subtilis (B. subtilis). Promoters for controlling N‐acetylglucosamine 2‐epimerase (AGE) and NeuAc adolase (NanA) are optimized, yielding 32.84 g L?1 NeuAc production with a molar conversion rate of 26.55% from N‐acetylglucosamine (GlcNAc). Next, NeuAc production is further enhanced to 46.04 g L?1, which is 40.2% higher than that of the strain with promoter optimization, by expressing NanA from Staphylococcus hominis instead of NanA from Escherichia coli. To enhance the expression level of ShNanA, the N‐terminal coding sequences of genes with high expression levels are fused to the 5′‐end of the ShNanA gene, resulting in 56.82 g L?1 NeuAc production. Finally, formation of the by‐product acetoin from pyruvate is blocked by deleting the alsS and alsD genes, resulting in 68.75 g L?1 NeuAc production with a molar conversion rate of 55.57% from GlcNAc. Overall, a GRAS B. subtilis strain is demonstrated as a whole‐cell biocatalyst for efficient NeuAc production. 相似文献