L-Sox5 and Sox6 proteins enhance chondrogenic miR-140 microRNA expression by strengthening dimeric Sox9 activity

Sox9 plays a critical role in early chondrocyte initiation and promotion as well as repression of later maturation. Fellow Sox family members L-Sox5 and Sox6 also function as regulators of cartilage development by boosting Sox9 activation of chondrocyte-specific genes such as Col2a1 and Agc1; however, the regulatory mechanism and other target genes are largely unknown. MicroRNAs are a class of short, non-coding RNAs that act as negative regulators of gene expression by promoting target mRNA degradation and/or repressing translation. Analysis of genetically modified mice identified miR-140 as a cartilage-specific microRNA that could be a critical regulator of cartilage development and homeostasis. Recent findings suggest Sox9 promotes miR-140 expression, although the detailed mechanisms are not fully understood. In this study we demonstrate that the proximal upstream region of pri-miR-140 has chondrogenic promoter activity in vivo. We found an L-Sox5/Sox6/Sox9 (Sox trio) response element and detailed binding site in the promoter region. Furthermore, detailed analysis suggests the DNA binding and/or transactivation ability of Sox9 as a homodimer is boosted by L-Sox5 and Sox6. These findings provide new insight into cartilage-specific gene regulation by the Sox trio.     

Free ion concentrations in receptor lymph and role of transepithelial voltage in the fly labellar taste receptor

Free ion concentrations in the receptor lymph of the labellar taste hair were examined on the fleshfly Boettcherisca peregrina, making use of several kinds of ion-selective microelectrodes inserted into the outer lumen of the taste hair through its cut end. The receptor lymph was rich in Na⁺ and Cl^- but poor in K⁺, that is, concentrations of free Na⁺, K⁺, Ca²⁺ and Cl^- were (in mM) 117,24,0.2 and 109, respectively. The haemolymph of this insect had similar free ion concentrations.Next, the role of transepithelial voltage (TEV; 47.1 ± 1.0 mV), which the receptor lymph space of the taste hair had with respect to the haemolymph, was examined. The quantitative relationship between the TEV amplitudes and the impulse frequencies of the sugar receptor evoked by sucrose stimulation was determined, changing TEV with application of respiratory inhibitors to the taste hair tip or by injecting current into the outer lumen. The TEV is concluded to provide the major component of the driving electromotive force for the receptor current to flow.     

Hyperphosphorylation at serine 199/202 of tau factor in the gerbil hippocampus after transient forebrain ischemia

We examined the phosphorylation state of tau factor in hippocampal delayed neuronal death (DND) after transient forebrain ischemia. A transient phosphorylation increase at serine 199/202 but not serine 396 of tau factor after transient ischemia was clearly observed. Intraventricular injections of olomoucine and U-0126 (CDK5 and MAP kinase inhibitors, respectively) inhibited hyperphosphorylation. In contrast, wortmannin (PI3 kinase inhibitor) increased phosphorylation at serine 199/202 and corresponded with an increase in GSK3 phosphorylation. Our findings suggest that CDK5, MAP kinase, and GSK3 phosphorylate these sites after ischemia. We prepared recombinant normal human tau (N-Tau40) with TAT-HA protein and dephosphorylated-form human Tau-40 (D-tau40) in which 199/202 serines were changed to alanine by site-directed mutagenesis. Intraventricularly injected D-tau40 protected somewhat against DND while N-Tau40 did not. These data suggest that hyperphosphorylation at serine 199/202 of tau factor is induced by MAP kinase, CDK5, and GSK3, and contributes to ischemic neuronal injury.     

Molecular oxygen regulates the enzymatic activity of a heme-containing diguanylate cyclase (HemDGC) for the synthesis of cyclic di-GMP

We have studied the structural and enzymatic properties of a diguanylate cyclase from an obligatory anaerobic bacterium Desulfotalea psychrophila, which consists of the N-terminal sensor domain and the C-terminal diguanylate cyclase domain. The sensor domain shows an amino acid sequence homology and spectroscopic properties similar to those of the sensor domains of the globin-coupled sensor proteins containing a protoheme. This heme-containing diguanylate cyclase catalyzes the formation of cyclic di-GMP from GTP only when the heme in the sensor domain binds molecular oxygen. When the heme is in the ferric, deoxy, CO-bound, or NO-bound forms, no enzymatic activity is observed. Resonance Raman spectroscopy reveals that Tyr55 forms a hydrogen bond with the heme-bound O₂, but not with CO. Instead, Gln81 interacts with the heme-bound CO. These differences of a hydrogen bonding network will play a crucial role for the selective O₂ sensing responsible for the regulation of the enzymatic activity.     

Cannabinoid Type 1 Receptors in the Basolateral Amygdala Regulate ACPA-Induced Place Preference and Anxiolytic-Like Behaviors

Neurochemical Research - The number of cannabis users is increasing in the world. However, the mechanisms involved in the psychiatric effects and addiction formation remain unclear. Medical...     

Pronounced conversion of the metal-specific activity of superoxide dismutase from Porphyromonas gingivalis by the mutation of a single amino acid (Gly155Thr) located apart from the active site

Glycine 155, which is located approximately 10 A from the active metal sites, is mostly conserved in aligned amino acid sequences of manganese-specific superoxide dismutases (Mn-SODs) and cambialistic SOD (showing the same activity with Fe and Mn) from Porphyromonas gingivalis, but is substituted for threonine in most Fe-SODs. Since Thr155 is located between Trp123 and Trp125, and Trp123 is one member of the metal-surrounding aromatic amino acids, there is a possibility that the conversion of this amino acid may cause a conversion of the metal-specific activity of cambialistic P. gingivalis SOD. To clarify this possibility, we have prepared a mutant of the P. gingivalis SOD with conversion of Gly155 to Thr. The ratios of the specific activities of Fe- to Mn-reconstituted enzyme, which are measured by the xanthine oxidase/cytochrome c method, increased from 0.6 in the wild-type to 11.2 in the mutant SODs, indicating the conversion of the metal-specific activity of the enzyme from a cambialistic type to an Fe-specific type. The visible absorption spectra of the Fe- and Mn-reconstituted mutant SODs closely resembled those of Fe-specific SOD. Furthermore, the EPR spectra of the Fe- and Mn-reconstituted mutant SODs also closely resembled those of Fe-specific SOD. Three-dimensional structures of the Fe-reconstituted wild-type SOD and Mn-reconstituted mutant SOD have been determined at 1.6 A resolution. Both structures have identical conformations, orientations of residues involved in metal binding, and hydrogen bond networks, while the side chain of Trp123 is moved further toward the metal-binding site than in wild-type SOD. A possible contribution of the structural differences to the conversion of the metal-specific activity through rearrangement of the hydrogen bond network among Trp123, Gln70, Tyr35, and the metal-coordinated solvent is discussed.     

Selective antiproliferative activity of caffeic acid phenethyl ester analogues on highly liver-metastatic murine colon 26-L5 carcinoma cell line

Caffeic acid phenethyl ester (CAPE, 2) and its twenty analogues (1, 3-21) were prepared. These esters were tested by MTT assay on growth of murine colon 26-L5 carcinoma, murine B16-BL6 malonoma, murine Lewis lung carcinoma, human HT-1080 fibrosarcoma, human lung A549 adenocarcinoma, and human cervix HeLa adenocarcinoma cell lines. It was found that CAPE analogues possessed selective antiproliferative activity toward highly liver-metastatic murine colon 26-L5 carcinoma cell line. Among them, 4-phenylbutyl caffeate (4), (Z)-8-phenyl-7-octenyl (10a) and (E)-8-phenyl-7-octenyl (10b) caffeate showed the most potent antiproliferative activity (EC50 value, 0.02 microM). In addition, CAPE (2) induced DNA fragmentation at concentrations of 1 to 10 microg/mL towards murine colon 26-L5 carcinoma cells.