Involvement of rBAT in Na(+)-dependent and -independent transport of the neurotransmitter candidate L-DOPA in Xenopus laevis oocytes injected with rabbit small intestinal epithelium poly A(+) RNA

Although L-3,4-dihydroxyphenylalanine (L-DOPA) is claimed to be a neurotransmitter in the central nervous system (CNS), receptor or transporter molecules for L-DOPA have not been determined. In an attempt to identify a transporter for L-DOPA, we examined whether or not an active and high affinity L-DOPA transport system is expressed in Xenopus laevis oocytes injected with poly A(+) RNA prepared from several tissues. Among the poly A(+) RNAs tested, rabbit intestinal epithelium poly A(+) RNA gave the highest transport activity for L-[(14)C]DOPA in the oocytes. The uptake was approximately five times higher than that of water-injected oocytes, and was partially Na(+)-dependent. L-Tyrosine, L-phenylalanine, L-leucine and L-lysine inhibited this transport activity, whereas D-DOPA, dopamine, glutamate and L-DOPA cyclohexylester, an L-DOPA antagonist did not affect this transport. Coinjection of an antisense cRNA, as well as oligonucleotide complementary to rabbit rBAT (NBAT) cDNA almost completely inhibited the uptake of L-[(14)C]DOPA in the oocytes. On the other hand, an antisense cRNA of rabbit 4F2hc barely affected this L-[(14)C]DOPA uptake activity. rBAT was thus responsible for the L-[(14)C]DOPA uptake activity expressed in X. laevis oocytes injected with poly A(+) RNA from rabbit intestinal epithelium. As rBAT is localized at the target regions of L-DOPA in the CNS, rBAT might be one of the components involved in L-DOPAergic neurotransmission.     

Possible involvement of Hcn1 ion channel in learning and memory dysfunction in SAMP8 mice

The senescence-accelerated mouse prone 8 (SAMP8) strain exhibits age-related learning and memory deficits (LMD) at 2 months of age. Combined linkage analysis of 264 F2 intercross SAMP8 × JF1 mice and RNA-seq analysis identified Hcn1 gene out of 29 genes in the LMD region on chromosome 13. Hcn1 in SAMP8 strain showed 15 times less polyglutamine repetition compared to Japanese fancy mouse 1 (JF1). Whole cell patch clamp analysis showed that Hcn1 ion conductivity was significantly lower in SAMP8 compared to that of JF1, which may be associated with learning and memory deficiency.     

Involvement of gicerin, a cell adhesion molecule, in development and regeneration of oviduct and metastasis of oviductal adenocarcinomas of the chicken

Gicerin is a novel cell adhesion molecule in the immunoglobulin superfamily and has both homophilic adhesion and heterophilic adhesive activity to neurite outgrowth factor (NOF), an extracellular matrix protein in the laminin family. We investigated the possible involvement of gicerin in oviductal development, regeneration, and metastasis of oviductal adenocarcinomas of the chicken. In the oviductal epithelium, gicerin was expressed strongly during development, disappeared after maturation, and reappeared during regeneration. NOF was constitutively expressed in the basement membrane of the epithelium. These molecules were expressed strongly in oviductal adenocarcinomas in both primary and metastatic lesions in the mesentery. An anti-gicerin antibody inhibited the attachment of adenocarcinoma cells to the mesentery in vitro. Many cells migrated from adenocarcinoma tissues on NOF, which were inhibited by an anti-gicerin antibody. These results suggest that gicerin might play a role in oviductal development and regeneration and also in the metastasis of adenocarcinomas.     

Settlement of Planulae of the Moon Jellyfish Aurelia aurita onto Hydrophilic Polycarbonate Plates Modified by Atmospheric Plasma Treatment

It has been reported that planula larvae of some jellyfish prefer artificial substrates for settlement. This research focused on the relationship between the settlement of planulae and the wettability of artificial substrate surfaces. We used atmospheric plasmas to change the wettability of the surfaces of polycarbonate (PC) plates because plasma treatment has no chemical side effects. The treatment made the surfaces hydrophilic, as evidenced by the decrease of contact angle from 85° to 35°. X-ray photoelectron spectroscopy revealed that the change of wettability of the PC plates could be attributed to N₂, which was probably ionized in the air above the plates. Scanning electron microscopy revealed no difference in the surface morphology of the plates before and after plasma treatment. Results of bioassays using treated PC plates showed that planulae tended to preferentially settle on hydrophobic surfaces.     

Identification of novel peptide agonists from a random peptide library for a 5-oxo-ETE receptor, a receptor for bioactive lipids

A combinatorial peptide library contains an enormous combination of amino acid sequences and drug candidates, but an effective screening strategy to identify a variety of bioactive peptides has yet to be established. In this article, a random hexapeptide library was screened to identify novel peptide ligands for a 5-oxo-ETE receptor (OXER), which is a G-protein-coupled receptor for bioactive lipids, by using an OXER-Gi1alpha fusion protein. We successfully identified 2 hexapeptides-Ac-HMQLYF-NH2 and Ac-HMWLYF-NH(2)-that exhibited agonistic activity. Although the corresponding affinities were relatively low (EC50 values of 146 and 6.7 microM, respectively), the activities were confirmed by other independent cell-based assay methods, namely, intracellular calcium mobilization and cell chemotaxis. This study demonstrates that a combinatorial peptide library may be screened using a [35S]GTPgammaS binding assay with G-protein-coupled receptor (GPCR)-Galpha fusion proteins, in general, and that of peptide ligands can be obtained even for nonpeptide receptors.     

Local mechanical properties measured by atomic force microscopy for cultured bovine endothelial cells exposed to shear stress

Morphology and mechanical properties of cultured endothelial cells were measured, using a novel atomic force microscope (AFM) system, developed in our laboratory, in conjunction with an inverted confocal laser scanning microscope. We used this system to examine endothelial cell both in static cultures and exposed to a shear stress of 2 Pa. Initially, the three-dimensional topography of a cell was measured by the AFM and a location was selected for the subsequent measurement of the mechanical response of the cell. The surface of statically cultured cell was smooth. The cell height was not altered by the exposed duration of shear stress. A relationship between external force, F, and the indentation depth, delta, was obtained for several different locations on a cell. This force-indentation response was modelled using a quadratic equation, F = adelta2 + bdelta, indicating that two parameters, a and b, will be constants which are representative of the mechanical response. Endothelial cells cultured at static conditions demonstrated a polygonal shape and less stiff mechanical characteristics around the nucleus compared to those at peripheral regions. The stiffness of the endothelial cells exposed to shear stress increased with the duration time of exposure. At 6-h exposures, the stiffness was higher at upstream side of the cell than the downstream side. However, after 24-h exposure, the stiffness was similar on both sides of the cell. These changes in the stiffness of endothelial cells when exposed to shear stress were suggested to correspond with the distribution of stress fibers in the cell.