Ricin A-chain can inactivate eukaryotic ribosomes, but exhibits no
N-glycosidase activity on intact
E. coli ribosomes. In the present research, in order to avoid using radiolabeled ...oligoribonucleotides, two kinds of synthetic 5′-FAM fluorescence-labeled oligoribonucleotide substrates were used to mimic the sarcin/ricin domains of rat 28S rRNA and
E. coli 23S rRNA (32mer and 25mer, named as Rat FAM-SRD and
E. coli FAM-SRD, respectively). Ricin A-chain was able to specifically release adenine from the first adenosine of the GAGA tetraloop and exhibited specific
N-glycosidase activity under neutral and weak acidic conditions with both substrates. However, under more acidic conditions, ricin A-chain was able to release purines from other sites on eukaryotic substrates, but it retained specific depurination activity on prokaryotic substrates. At pH 5.0, the Michaelis constant (
K
m) for the reaction with
Rat FAM-SRD (4.57
±
0.28
μM) corresponded to that with
E. coli FAM-SRD (4.64
±
0.26
μM). However, the maximum velocity (
V
max) for ricin A-chain with Rat FAM-SRD was 0.5
±
0.024
μM/min, which is higher than that with
E. coli FAM-SRD (0.32
±
0.011
μM/min).
Binding of Sonic Hedgehog (Shh) to Patched (Ptc) relieves the latter's tonic inhibition of Smoothened (Smo), a receptor that spans the cell membrane seven times. This initiates signaling which, by ...unknown mechanisms, regulates vertebrate developmental processes. We find that two molecules interact with mammalian Smo in an activation-dependent manner: G protein-coupled receptor kinase 2 (GRK2) leads to phosphorylation of Smo, and beta-arrestin 2 fused to green fluorescent protein interacts with Smo. These two processes promote endocytosis of Smo in clathrin-coated pits. Ptc inhibits association of beta-arrestin 2 with Smo, and this inhibition is relieved in cells treated with Shh. A Smo agonist stimulated and a Smo antagonist (cyclopamine) inhibited both phosphorylation of Smo by GRK2 and interaction of beta-arrestin 2 with Smo. beta-Arrestin 2 and GRK2 are thus potential mediators of signaling by activated Smo.
To investigate the effects of natural drug curcumin (Cur) on apoptosis of lens epithelial cell (LEC) in vitro and its mechanism.
The bovine LEC were cultured with Cur, the ultrastructure changes were ...observed under transmission electron microscope (TEM), the DNA content and mitochondrial transmembrane potential (DeltaPsim) changes were studied by flow cytometry (FCM).
The typical morphological changes of LEC apoptosis in Cur group detected by TEM included chromatin condensation and aggregation at the periphery of the nucleons and nuclear fragmentation. The DNA content of LEC in Cur group decreased time-dependently. The DNA content was significantly lower than that of the control group (P < 0.01). The DeltaPsim of LEC in Cur group was decreased, appeared in early stage (8 hours) and reached the maximum after 72 hours. The difference of DeltaPsim of LEC between Cur group and the control group was significant (P < 0.01).
Cur can remarkably induce apoptosis of LEC in vitro. Cur induced LEC apoptosis is caused by
This study was conducted to identify polymorphisms of the Nangyang cattle's growth hormone (GH) and insulin-like growth factor-I (IGF-I) and insulin-like growth factor-I binding protein 3(IGF-IBP3) ...gene by the single nucleotide Polymorphisms and Polymerase chain reaction-based restriction fragment length polymorphism and to study association of polymorphisms identified in these genes with growth traits of the birth, 6 months, 12 months, 18 months, 24 months and 36 months. Results from the analysis showed a significant association of the BB genotype in the promoter of GH gene (GH-P5) with higher body length and body height during from 6 month to 18 month. From 24 month to 36 month, the IGF-IBP3 locus has a dominance modulation and control effect on backbody in Nanyang Cattle, and the BB genotype with higher Rump width than AA.
The growth-inhibiting effects of Gemini1231 surfactant on Prorocentrum donghaiense, Alexandrium tamarense, Gymnodinium sp., Heterosigma akashiwo, Skeletonema costatum , Platymonas helgolanidica and ...Platymonas subcordiforus were investigated. The results demonstrate that the growth of P. donghaiense, A. tamarense and H. akashiwo was strongly inhibited in medium containing Gemini1231 from 0.2 to 0.5 mg x L(-1), and the S. costatum was also inhibited at concentrations above 0.5 mg x L(-1). However, the effects of this surfactant on the growth of Gymnodinium sp. and two beneficial green microalgae tested were negligible under the same treatment, indicating the potential for the selective control of red tide organisms. In addition, the analysis of the correlation between the inhibitory effect of the Gemini1231 on the algae tested and fatty acid composition of the algae implied that the differences in the fatty acid composition, especially the proportion of PUFAs, were responsible for the species-specific responses
Binding of Sonic Hedgehog (Shh) to Patched (Ptc) relieves the latter's tonic inhibition of Smoothened (Smo), a receptor that spans the cell membrane seven times. This initiates signaling which, by ...unknown mechanisms, regulates vertebrate developmental processes. We find that two molecules interact with mammalian Smo in an activation-dependent manner: G protein–coupled receptor kinase 2 (GRK2) leads to phosphorylation of Smo, and β-arrestin 2 fused to green fluorescent protein interacts with Smo. These two processes promote endocytosis of Smo in clathrin-coated pits. Ptc inhibits association of β-arrestin 2 with Smo, and this inhibition is relieved in cells treated with Shh. A Smo agonist stimulated and a Smo antagonist (cyclopamine) inhibited both phosphorylation of Smo by GRK2 and interaction of β-arrestin 2 with Smo. β-Arrestin 2 and GRK2 are thus potential mediators of signaling by activated Smo.
To investigate the relationship among inflammatory reaction and cytokine levels, nitric oxide (NO) content in aqueous humor after intraocular lens implantation.
Eighteen New Zealand rabbits were ...divided randomly into 3 groups (each 6 rabbits): (1) control group, (2) extracapsular cataract extraction group (ECCE) and (3) ECCE and posterior chamber intraocular lens implantation group (ECCE + IOL). The inflammation of all experimental rabbit eyes were observed by a zoom-photo slit-lamp microscope 0, 1, 3, 7, 14, 30 days postoperatively, including corneal edema and anterior chamber exudation. Meanwhile, aqueous humor was drawn for white blood cell (WBC) count and classification, as well as for NO(2)(-)/NO(3)(-) and cytokine assays, including interleukin-2 (IL-2), tumor necrosis factor-alpha (TNF-alpha). Statistics were taken by SPSS software.
(1) The anterior chamber exudation was the most serious and monocyte/macrophage in aqueous humor were the highest in ECCE + IOL group in postoperative 7 - 14 days. (2) The l
beta-Arrestins, originally discovered as terminators of G protein-coupled receptor signaling, have more recently been appreciated to also function as signal transducers in their own right, although ...the consequences for cellular physiology have not been well understood. Here we demonstrate that beta-arrestin-2 mediates anti-apoptotic cytoprotective signaling stimulated by a typical 7-transmembrane receptor the angiotensin ATII 1A receptor, expressed endogenously in rat vascular smooth muscle cells or by transfection in HEK-293 cells. Receptor stimulation leads to concerted activation of two pathways, ERK/p90RSK and PI3K/AKT, which converge to phosphorylate and inactivate the pro-apoptotic protein BAD. Anti-apoptotic effects as well as pathway activities can be stimulated by an angiotensin analog (SII), which has been previously shown to activate beta-arrestin but not G protein-dependent signaling, and are abrogated by beta-arrestin-2 small interfering RNA. These findings establish a key role for beta-arrestin-2 in mediating cellular cytoprotective functions by a 7-transmembrane receptor and define the biochemical pathways involved.
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