The cystic fibrosis transmembrane conductance regulator (CFTR) is a unique member of the ATP-binding cassette (ABC) transporter superfamily that forms a Cl(-) channel with complex regulation. CFTR is composed of five domains: two membrane-spanning domains (MSDs), two nucleotide-binding domains (NBDs) and a unique regulatory domain (RD). The MSDs assemble to form a low conductance (6-10 pS) anion-selective pore with deep intracellular and shallow extracellular vestibules separated by a selectivity filter. The NBDs form a head-to-tail dimer with two ATP-binding sites (termed sites 1 and 2) located at the dimer interface. Anion flow through CFTR is gated by the interaction of ATP with sites 1 and 2 powering cycles of NBD dimer association and dissociation and hence, conformational changes in the MSDs that open and close the channel pore. The RD is an unstructured domain with multiple consensus phosphorylation sites, phosphorylation of which stimulates CFTR function by enhancing the interaction of ATP with the NBDs. Tight spatial and temporal control of CFTR activity is achieved by macromolecular signalling complexes in which scaffolding proteins colocalise CFTR and plasma membrane receptors with protein kinases and phosphatases. Moreover, a macromolecular complex composed of CFTR and metabolic enzymes (a CFTR metabolon) permits CFTR activity to be coupled tightly to metabolic pathways within cells so that CFTR inhibition conserves vital energy stores. CFTR is expressed in epithelial tissues throughout the body, lining ducts and tubes. It functions to control the quantity and composition of epithelial secretions by driving either the absorption or secretion of salt and water. Of note, in the respiratory airways CFTR plays an additional important role in host defence. Malfunction of CFTR disrupts transepithelial ion transport leading to a wide spectrum of human disease.
Cystic Fibrosis Transmembrane Conductance Regulator ; physiology ; Epithelium ; physiology ; Humans ; Ion Transport ; Phosphorylation ; Protein Interaction Domains and Motifs

Mesothelial cells (MCs) cover the surface of visceral organs and the parietal walls of cavities, and they synthesize lubricating fluids to create a slippery surface that facilitates movement between organs without friction. Recent studies have indicated that MCs play active roles in liver development, fibrosis, and regeneration. During liver development, the mesoderm produces MCs that form a single epithelial layer of the mesothelium. MCs exhibit an intermediate phenotype between epithelial cells and mesenchymal cells. Lineage tracing studies have indicated that during liver development, MCs act as mesenchymal progenitor cells that produce hepatic stellate cells, fibroblasts around blood vessels, and smooth muscle cells. Upon liver injury, MCs migrate inward from the liver surface and produce hepatic stellate cells or myofibroblast depending on the etiology, suggesting that MCs are the source of myofibroblasts in capsular fibrosis. Similar to the activation of hepatic stellate cells, transforming growth factor β induces the conversion of MCs into myofibroblasts. Further elucidation of the biological and molecular changes involved in MC activation and fibrogenesis will contribute to the development of novel approaches for the prevention and therapy of liver fibrosis.
Epithelial Cells/*physiology ; Epithelium/metabolism ; Hepatic Stellate Cells/*physiology ; Humans ; Liver/*cytology/injuries/*physiology ; Liver Cirrhosis/etiology/prevention & control ; Liver Regeneration/*physiology ; Mesenchymal Stromal Cells/physiology ; Myofibroblasts/physiology

In addition to its well established role as a neurotransmitter, extracellular ATP has been considered as a paracrine/autocrine factor, either released from sperm or epithelial cells, in the male reproductive tract and shown to play a versatile role in modulating various reproductive functions. This review summarizes the signal pathways through which ATP induces anion secretion by the epithelia of the epididymis, as well as its epithelium-dependent modulation of smooth muscle contraction of the vas deferens. Finally, the overall role of ATP in coordinating various reproductive events in the male genital tract is discussed.
Adenosine Triphosphate ; physiology ; Animals ; Epididymis ; physiology ; Epithelium ; physiology ; Humans ; Male ; Muscle Contraction ; Muscle, Smooth ; physiology ; Signal Transduction ; Urogenital System ; physiology ; Vas Deferens ; physiology

Salivary glands provide saliva to maintain oral health, and a loss of salivary gland function substantially decreases quality-of-life. Understanding the biological mechanisms that generate salivary glands during embryonic development may identify novel ways to regenerate function or design artificial salivary glands. This review article summarizes current research on the process of branching morphogenesis of salivary glands, which creates gland structure during development. We highlight exciting new advances and opportunities in studies of cell-cell interactions, mechanical forces, growth factors, and gene expression patterns to improve our understanding of this important process.
Animals ; Cell Communication ; physiology ; Embryonic Development ; physiology ; Epithelium ; embryology ; Extracellular Matrix ; physiology ; Humans ; Intercellular Signaling Peptides and Proteins ; physiology ; Morphogenesis ; physiology ; Salivary Glands ; embryology

BACKGROUNDThe cell layer of the ciliary epithelium is responsible for aqueous humor secretion and maintenance. Ion channels play an important role in these processes. The main aim of this study was to determine whether the well-characterized members of the Kv1 family (Kv1.3) contribute to the Kv currents in ciliary epithelium.

METHODSNew Zealand White rabbits were maintained in a 12 hours light/dark cycle. Ciliary epithelium samples were isolated from the rabbits. We used Western blotting and immunocytochemistry to identify the expression and location of a voltage-gated potassium channel Kv1.3 in ciliary body epithelium. Membrane potential change after adding of Kv1.3 inhibitor margatoxin (MgTX) was observed with a fluorescence method.

RESULTSWestern blotting and immunocytochemical studies showed that the Kv1.3 protein expressed in pigment ciliary epithelium and nonpigment ciliary epithelium, however it seemed to express more in the apical membrane of the nonpigmented epithelial cells. One nmol/L margatoxin, a specific inhibitor of Kv1.3 channels caused depolarization of the cultured nonpigmented epithelium (NPE) membrane potential. The cytosolic calcium increased after NPE cell depolarization, this increase of cytosolic calcium was partially blocked by 12.5 micromol/L dantrolene and 10 micromol/L nifedipine. These observations suggest that Kv1.3 channels modulate ciliary epithelium potential and effect calcium dependent mechanisms.

CONCLUSIONKv1.3 channels contribute to K+ efflux at the membrane of rabbit ciliary epithelium.

Animals ; Blotting, Western ; Calcium ; metabolism ; Ciliary Body ; cytology ; metabolism ; physiology ; Immunohistochemistry ; In Vitro Techniques ; Kv1.3 Potassium Channel ; metabolism ; physiology ; Membrane Potentials ; physiology ; Pigment Epithelium of Eye ; cytology ; metabolism ; physiology ; Rabbits

The root is crucial for the physiological function of the tooth, and a healthy root allows an artificial crown to function as required clinically. Tooth crown development has been studied intensively during the last few decades, but root development remains not well understood. Here we review the root development processes, including cell fate determination, induction of odontoblast and cementoblast differentiation, interaction of root epithelium and mesenchyme, and other molecular mechanisms. This review summarizes our current understanding of the signaling cascades and mechanisms involved in root development. It also sets the stage for de novo tooth regeneration.
Cell Differentiation ; genetics ; Dental Cementum ; physiology ; Epithelium ; physiology ; Humans ; Mesoderm ; physiology ; Molecular Biology ; Odontoblasts ; physiology ; Odontogenesis ; genetics ; Signal Transduction ; genetics ; Tooth Root ; embryology ; growth & development

A closed eyeball model was designed to estimate the chorioretinal adhesion of the laser-photocoagulated region. We used it to measure the duration of development of retinal detachment during vitrectomy before and after killing the test rabbits. During testing, negative pressure was applied into the vitreous cavity of the pigmented rabbits. Laser burns were produced in the posterior retina by exposure to an argon blue-green laser beam with a focus diameter of 200 microns of 0.1 to 0.2 second duration and 150 to 250 mW intensity. One hour and one, two, five, seven and fourteen days following laser photocoagulation, vitrectomy was done with a cutting rate of 500 per minute, aspiration pressure of 50 mmHg and infusion pressure of 55.2 mmHg. After core vitrectomy, the rabbit was killed with an intravenous bolus of 100 mg sodium pentobarbital solution. After killing the rabbit, the vitreous cavity was continuously aspirated under the pressure of 25 mmHg while the infusion was stopped. The changes of the fundus, especially development of retinal detachment, were observed in the laser-treated and untreated regions before and after killing the rabbit. When retinal detachment was noted anywhere before killing the rabbit, this postmortem change was not observed. One hour following laser photocoagulation, the laser-treated retina was detached during core vitrectomy before killing the rabbit, and the untreated area was not detached. One day following photocoagulation, the retina was intact before killing the rabbit. After killing the rabbit, the laser-treated retina was detached in four minutes and the untreated retina in 18 minutes postmortem.
Adhesiveness ; Animal ; *Laser Coagulation ; Pigment Epithelium of Eye/*physiology ; Rabbits ; Retina/*physiology ; Retinal Detachment/prevention & control ; Time Factors

It is known that CD95 (APO-1/Fas) is expressed on the cell surface, and apoptotic cell death can be induced by the CD95 ligation in the cultured, proliferating human retinal pigment epithelial (RPE) cells. However, little is known about CD95 on the non-proliferating RPE cells. In this study, human RPE cells were cultured up to 4 weeks after they reached the confluence, to simulate the non-proliferating RPE cells in situ. There was no significant difference in CD95 expression on the cell surface between the predominantly proliferating, preconfluent cells and predominantly non-proliferating, postconfluent cells in flow cytometric assays. However, unlike proliferating cells, no cellular death occurred in the predominantly non-proliferating cells after the treatment of agonistic anti-CD95 antibody with cycloheximide, pretreated with interferon-gamma. Our results suggest that the CD95/CD95L system probably plays a physiologic role in vivo to remove the abnormal, proliferating RPE cells, and factors other than the surface expression of CD95 may determine the sensitivity to the CD95 signals.
Antigens, CD95/*pharmacology ; Apoptosis/*physiology ; Cells, Cultured ; Human ; Pigment Epithelium of Eye/cytology/*drug effects/*physiology ; Sensitivity and Specificity

OBJECTIVESTo investigate the effects of newborn bull serum(NBS), vitamin C and vitamin E on cryopreservation of mouse seminiferous epithelial cells.

METHODSThe seminiferous epithelial cells from 7-day-old mice were cryopreserved in different freezing solutions. The cell recoveries were examined by Trypan blue exclusive staining after thawing. The freezing solutions composed of DMEM, 10% dimethylsulphoxide(DMSO), and 0, 5%, 10%, or 20% NBS, respectively, or composed of DMEM, 10% DMSO, 10% NBS, and 150 micrograms/ml vitamin C or 50 micrograms/ml vitamin E, respectively.

RESULTSThe cell recoveries in freezing solution containing 0, 5%, 10%, or 20% NBS were 83.4%, 84.7%, 85.7% and 83.6%, respectively. There were no significant differences between them. The cell recoveries in freezing solution containing vitamin C or vitamin E were 88.0% and 82.9%, respectively. There was no significant differences compared with that in freezing solution containing 10% DMSO and 10% NBS.

CONCLUSIONSNBS, vitamin C and vitamin E have no significant protecting effects on mouse seminiferous epithelial cells, and can not significantly improve the cell recoveries.

Animals ; Ascorbic Acid ; pharmacology ; Cattle ; Cryopreservation ; Epithelial Cells ; physiology ; Fetal Blood ; physiology ; Male ; Mice ; Seminiferous Epithelium ; cytology ; Vitamin K ; pharmacology

In the retina, pH fluctuations may play an important role in adapting retinal responses to different light intensities and are involved in the fine tuning of visual perception. Acidosis occurs in the subretinal space (SRS) under pathological conditions such as age-related macular degeneration (AMD). Although it is well known that many transporters in the retinal pigment epithelium (RPE) cells can maintain pH homeostasis efficiently, other receptors in RPE may also be involved in sensing acidosis, such as acid-sensing ion channels (ASICs). In this study, we investigated whether ASIC1a was expressed in the RPE cells and whether it was involved in the function of these cells. Real-time RT-PCR and Western blotting were used to analyze the ASIC1a expression in ARPE-19 cells during oxidative stress induced by hydrogen peroxide (H(2)O(2)). Furthermore, inhibition or over-expression of ASIC1a in RPE cells was obtained using inhibitors (amiloride and PCTx1) or by the transfection of cDNA encoding hASIC1a. Cell viability was determined by using the MTT assay. The real-time RT-PCR and Western blotting results showed that both the mRNA and protein of ASIC1a were expressed in RPE cells. Inhibition of ASICs by amiloride in normal RPE cells resulted in cell death, indicating that ASICs play an important physiological role in RPE cells. Furthermore, over-expression of ASIC1a in RPE cells prolonged cell survival under oxidative stress induced by H(2)O(2). In conclusion, ASIC1a is functionally expressed in RPE cells and may play an important role in the physiological function of RPE cells by protecting them from oxidative stress.
Acid Sensing Ion Channels ; metabolism ; Cell Line ; Humans ; Ion Channel Gating ; physiology ; Oxidative Stress ; physiology ; Retinal Pigment Epithelium ; cytology ; metabolism