Ovarian steroids modulate uterine receptivity in domestic species. Luteinizing hormone (LH) stimulates prostaglandin (PG)F(2alpha) release from the porcine endometrium. However, the combined action of LH and steroids on PGs secretion has not yet been studied in pigs. The aim of the present study was to examine the effect of estradiol (E(2)) and progesterone (P(4)) on basal and LH-stimulated PGF(2alpha) and PGE(2) secretion and cyclooxygenase-2 (COX-2) protein expression in porcine endometrial stromal cells obtained on days 12-13 of the estrous cycle. Cells were cultured for 48 h in a medium containing charcoal-stripped newborn calf serum alone or supplemented with 10 nM E(2) and/or 50 nM P(4). Then, the cells were incubated for 6 h in the presence or absence of LH (20 ng/ml). Long exposure of stromal cells to steroids had no effect on PGF(2alpha) secretion, but PGE(2) release increased in the presence of E(2) plus P(4) (p<0.05). Pre-incubation of cells with E(2) plus P(4) resulted in enhanced PGF(2alpha) (p<0.05) and PGE(2) (p<0.001) secretion. Moreover, LH increased PG(2alpha) secretion in control (p<0.05) and E(2)-treated stromal cells (p<0.01). LH tended (p=0.07) to elevate PGE(2) release only in cells pre-exposed to E(2) plus P(4). The expression of COX-2 protein was increased by LH (p<0.05), but not by steroids. These results confirm the stimulatory effect of LH on PGF(2alpha) secretion and COX-2 expression in porcine stromal cells before luteolysis. PG release from porcine endometrium seems to be controlled by ovarian steroids, however only E(2)-treated-treated cells responded to LH. 相似文献
The bovine mammary gland undergoes intensive remodelling during the lactation cycle, and the escalation of this process is observed during dry periods. The main type of cell death responsible for bovine mammary gland involution is apoptosis; however, there are also a lot of cells exhibiting morphological features of autophagy during drying off. Our in vitro and in vivo studies of bovine mammary gland physiology suggest that the enhanced process of autophagy, observed at the end of lactation and during dry periods, is the result of: (1) decreased level of lactogenic hormones (GH, IGF-I), (2) decreased GH-R and IGF-IR alpha expression, (3) increased expression of auto/paracrine apoptogenic peptides (IGFBPs, TGFbeta), (4) increased influence of sex steroids (17beta-estradiol and progesterone) and (5) enhanced competition between the between the intensively developing fetus and the mother organism for nutritional and bioactive compounds. The above conditions may create a state of temporary malnutrition of mammary epithelial cells, which forces the cells to the induction of autophagy, as a mechanism for stabilizing intracellular supplies of energy and amino acids, especially during the enhanced activity of apoptogenic factors. 相似文献
Allelopathy refers to plant-plant interference mediated mostly by plant released products of secondary metabolism. It was recently suggested that allelochamicals may influence growth of neighboring plants by induction of oxidative stress. We have focused on the role of reactive oxygen species (ROS) and phytohormons (ABA and ethylene) in the biochemical and molecular regulation of plant response to sunflower phytotoxins.Key Words: ABA, allelopathy, ethylene, H2O2, reactive oxygen species, seed germination相似文献
Gaucher disease is a lysosomal storage disorder caused by deficiency of human acid β-glucosidase. Recent x-ray structural
elucidation of the enzyme alone and in the presence of its inhibitor was done, which provided an excellent template for further
studies on the binding of substrate, product and inhibitor. To draw correlations between the clinical manifestation of the
disease driven by point mutations, L444P and L444R, and the placement and function of putative S-binding sites, the presented
theoretical studies were undertaken, which comprised of molecular dynamics and molecular docking methods. The obtained results
indicate the D443 and D445 residues as extremely important for physiological functionality of an enzyme. They also show, although
indirectly, that binding of the substrate is influenced by an interplay of E235 and E334 residues, constituting putative substrate
binding site, and the region flanked by D435 and D445 residues.
Figure The binding of an arbitrarily chosen structure of glucosylceramide (A), conduritol-β-epoxide (B), glucose (C) to the active
site D443/D445 (A1, B1, C1) and E320/E340 (A2, B2, C2) of the wild-type structure of human acid-β-glucosidase. A1, B1, C1
blue mask represents the residues D443-D445; red mask represents the residue D444; A2, B2, C2 blue mask represents loop1 (Ser345-Glu349) and loop2 (Val394-Asp399), whereas red mask the residues E235 and 340 相似文献
The plastid-encoded psaJ gene encodes a hydrophobic low-molecular-mass subunit of photosystem I (PSI) containing one transmembrane helix. Homoplastomic transformants with an inactivated psaJ gene were devoid of PSI-J protein. The mutant plants were slightly smaller and paler than wild-type because of a 13% reduction in chlorophyll content per leaf area caused by an approximately 20% reduction in PSI. The amount of the peripheral antenna proteins, Lhca2 and Lhca3, was decreased to the same level as the core subunits, but Lhca1 and Lhca4 were present in relative excess. The functional size of the PSI antenna was not affected, suggesting that PSI-J is not involved in binding of light-harvesting complex I. The specific PSI activity, measured as NADP(+) photoreduction in vitro, revealed a 55% reduction in electron transport through PSI in the mutant. No significant difference in the second-order rate constant for electron transfer from reduced plastocyanin to oxidized P700 was observed in the absence of PSI-J. Instead, a large fraction of PSI was found to be inactive. Immunoblotting analysis revealed a secondary loss of the luminal PSI-N subunit in PSI particles devoid of PSI-J. Presumably PSI-J affects the conformation of PSI-F, which in turn affects the binding of PSI-N. This together renders a fraction of the PSI particles inactive. Thus, PSI-J is an important subunit that, together with PSI-F and PSI-N, is required for formation of the plastocyanin-binding domain of PSI. PSI-J is furthermore important for stability or assembly of the PSI complex. 相似文献
Liver, as one of the most important organs involved in lipids and glucose metabolism, is perceived as a key tissue for pharmacotherapy of insulin resistance (IRes) and type 2 diabetes. Ceramides (Cer) are biologically active lipids, which accumulation is associated with the induction of muscle IRes. We sought to determine the role of intrahepatic bioactive lipids production on insulin action in liver of insulin-resistant rats and after myriocin administration. The experiments were conducted on male Wistar rats divided into three groups: Control, fed high-fat diet (HFD), and fed HFD and treated with myriocin (HFD/Myr). Before sacrifice, the animals were infused with a [U-13C]palmitate to calculate lipid synthesis rate by means of tracer incorporation technique in particular lipid groups. Liver Cer, diacylglycerols (DAG), acyl-carnitine concentration, and isotopic enrichment were analyzed by LC/MS/MS. Proteins involved in lipid metabolism and insulin pathway were analyzed by western blot analysis. An OGTT and ITT was also performed. HFD-induced IRes and increased both the synthesis rate and the content of DAG and Cer, which was accompanied by inhibition of an insulin pathway. Interestingly, myriocin treatment reduced synthesis rate not only of Cer but also DAG and improved insulin sensitivity. We conclude that the insulin-sensitizing action of myriocin in the liver is a result of the lack of inhibitory effect of lipids on the insulin pathway, due to the reduction of their synthesis rate. This is the first study showing how the synthesis rate of individual lipid groups in liver changes after myriocin administration. 相似文献
Pyrroloquinoline quinone (PQQ) acts as a powerful modulator of PGC-1α activation and therefore regulates multiple pathways involved in cellular energy homeostasis. In the present study, we assessed the effects of L6 myotubes incubation with 0.5, 1, and 3 μM PQQ solution for 2 and 24 hr with respect to the cells' lipid metabolism. We demonstrated that PQQ significantly elevates PGC-1α content in a dose- and time-dependent manner with the highest efficiency for 0.5 and 1 µM. The level of free fatty acids was diminished (24 hr: −66%), while an increase in triacylglycerol (TAG) amount was most pronounced after 0.5 μM (2 hr: +93%, 24 hr: +139%) treatment. Ceramide (CER) content was elevated after 2 hr incubation with 0.5 µM and after prolonged exposure to all PQQ concentrations. The cells treated with PQQ for 2 hr exhibited decreased sphinganine (SFA) and sphinganine-1-phosphate (SFA1P) level, while 24 hr incubation resulted in an elevated sphingosine (SFO) amount. In summary, PGC-1α activation promotes TAG and CER synthesis. 相似文献
This is the first study to generate carrot plants for enhanced salinity tolerance using a single-cell in vitro system. Protoplasts of three carrot accessions were exposed to treatment by seven different concentrations of NaCl (10–400 mM). Salt concentrations higher than 50 mM decreased plating efficiency and those of 200–400 mM of NaCl completely arrested mitotic divisions of cultured cells. The protoplast-derived plants from the control and 50–100 mM NaCl treatment were subjected to an 8-week salt stress in greenhouse conditions induced by salinized soil (EC 3 and 6 mS cm?1). 50 mM NaCl stress applied in vitro induced polyploidy among regenerated plants. The regenerants obtained from the 50 and 100 mM NaCl-treated protoplast cultures grown in saline soil had a higher survival rate compared to the regenerants from the control cultures. The salt-stressed plants accumulated anthocyanins in petioles and produced denser hairs on leaves and petioles in comparison to the control plants. Salt stress influenced pollen viability and seed setting of obtained regenerants. The results suggest that salt stress applied in vitro in protoplast cultures creates variation which allows alleviating the negative effects of salt stress on the development and reproduction of the carrot.
With the advance of experimental procedures obtaining chemical crosslinking information is becoming a fast and routine practice. Information on crosslinks can greatly enhance the accuracy of protein structure modeling. Here, we review the current state of the art in modeling protein structures with the assistance of experimentally determined chemical crosslinks within the framework of the 13th meeting of Critical Assessment of Structure Prediction approaches. This largest-to-date blind assessment reveals benefits of using data assistance in difficult to model protein structure prediction cases. However, in a broader context, it also suggests that with the unprecedented advance in accuracy to predict contacts in recent years, experimental crosslinks will be useful only if their specificity and accuracy further improved and they are better integrated into computational workflows. 相似文献
Subnuclear localization of topoisomerase I (top I) is determined by its DNA relaxation activity and a net of its interactions with in majority unidentified nucleolar and nucleoplasmic elements. Here, we recognized SR protein SRSF1 (Serine/arginine-rich splicing factor 1, previously known as SF2/ASF) as a new element of the net. In HeLa cells, overexpression of SRSF1 recruited top I to the nucleoplasm whereas its silencing concentrated it in the nucleolus. Effect of SRSF1 was independent of top I relaxation activity and was the best pronounced for the mutant inactive in relaxation reaction. In HCT116 cells where top I was not released from the nucleolus upon halting relaxation activity, it was also not relocated by elevated level of SRSF1. Out of remaining SR proteins, SRSF5, SRSF7, and SRSF9 did not influence the localization of top I in HeLa cells whereas overexpression of SRSF2, SRSF3, SRSF6, and partly SRSF4 concentrated top I in the nucleolus, most possibly due to the reduction of the SRSF1 accessibility. Specific effect of SRSF1 was exerted because of its distinct RS domain. Silencing of SRSF1 compensated the deletion of the top I N-terminal region, individually responsible for nucleoplasmic localization of the mutant, and restored the wild-type phenotype of deletion mutant localization. SRSF1 was essential for the camptothecin-induced clearance from the nucleolus. These results suggest a possible role of SRSF1 in establishing partition of top I between the nucleolus and the nucleoplasm in some cell types with distinct combinations of SR proteins levels. 相似文献