Cloning and functional characterization of a second urea transporter from the kidney of the Atlantic stingray, Dasyatis sabina.

The cloning of cDNAs encoding facilitated urea transporters (UTs) from the kidneys of the elasmobranchs indicates that in these fish renal urea reabsorption occurs, at least in part, by passive processes. The previously described elasmobranch urea transporter clones from shark (shUT) and stingray (strUT-1) differ from each other primarily because of the COOH-terminus of the predicted strUT-1 translation product being extended by 51-amino acid residues compared with shUT. Previously, we noted multiple UT transcripts were present in stingray kidney.

17beta-estradiol attenuates glutamate-induced apoptosis and preserves electrophysiologic function in primary cortical neurons.

Glutamate toxicity causes neuronal death in neurodegenerative diseases; hence, there is a need for therapeutic agents rendering functional neuroprotection. We tested the effects of 17beta-estradiol (estrogen) in rat primary cortical neurons after glutamate exposure. Wright staining and ApopTag assays indicated that 0.

Water permeability of C-terminally truncated aquaporin 0 (AQP0 1-243) observed in the aging human lens.

Purpose: To first assess the distribution of posttranslationally truncated products of aquaporin 0 (AQP0) in dissected sections of a normal human lens and to determine the effect of backbone cleavage on the water permeability of AQP0.

Methods: A 27-year-old lens was concentrically dissected into six sections. Membrane protein was isolated from each section and cleaved with cyanogen bromide, and the peptides were separated and analyzed by reverse-phase (RP)-HPLC-mass spectrometry (MS).

Identification of an alternatively processed nicotinic receptor alpha7 subunit RNA in mouse brain.

The data in this report describe the discovery and characterization of a previously unidentified alternatively processed RNA for the neuronal nicotinic receptor alpha7 subunit. The unique transcript contains an extra exon that arises from alternative splicing of intron nine of the alpha7 subunit RNA. The alpha7 subunit protein resulting from this alternatively processed RNA is truncated shortly after transmembrane domain three.

Estrogen attenuates oxidative stress-induced apoptosis in C6 glial cells.

We examined the mechanism of 17beta-estradiol (estrogen)-mediated inhibition of apoptosis in C6 (rat glioma) cells following exposure to hydrogen peroxide (H(2)O(2)). Cells were preincubated with 4 microM estrogen for 2 h and then exposed to 100 microM H(2)O(2) for 24 h. Exposure to H(2)O(2) caused significant increases in intracellular calcium (Ca(2+)), as determined by fura-2, which was attenuated by preincubation with estrogen.

Molecular and functional characterization of a urea transporter from the kidney of the Atlantic stingray.

In general, marine elasmobranch fishes (sharks, skates, and rays) maintain body fluid osmolality above seawater, principally by retaining large amounts of urea. Maintenance of the high urea concentration is due in large part to efficient renal urea reabsorption. Regulation of renal urea reabsorption also appears to play a role in maintenance of fluid homeostasis of elasmobranchs that move between habitats of different salinities.

Molecular and functional characterization of a urea transporter from the kidney of a short-finned pilot whale.

Cetaceans (whales and dolphins) always excrete urine with an osmolality markedly higher than that of plasma. Although the mechanisms by which cetaceans concentrate urine have not been elucidated, data support a role for medullary urea accumulation in this process, as is the case for terrestrial mammals. Therefore, we hypothesized that facilitated urea transporters are present in the kidney of cetaceans.

Activator of G-protein signaling 1 blocks GIRK channel activation by a G-protein-coupled receptor: apparent disruption of receptor signaling complexes.

The Ras-related protein, activator of G-protein signaling 1 (AGS1) or Dexras1, interacts with G(i)/G(o)alpha and activates heterotrimeric G-protein signaling systems independent of a G-protein-coupled receptor (GPCR). As an initial approach to further define the cellular role of AGS1 in GPCR signaling, we determined the influence of AGS1 on the regulation of G(betagamma)-regulated inwardly rectifying K(+) channel (GIRK) current (I(ACh)) by M(2)-muscarinic receptor (M(2)-MR) in Xenopus oocytes. AGS1 expression inhibited receptor-mediated current activation by >80%.