Neural Activity Affects Distribution of Glutamate Receptors during Neuromuscular Junction Formation inDrosophilaEmbryos

AbstractChanges in the distribution and density of transmitter receptors in the postsynaptic cell are required steps for functional synapse formation. We raised antibodies againstDrosophilaglutamate receptors (DGluR-II) and visualized the distribution of receptors during neuromuscular junction formation in embryos. In wild-type embryos, embryonic development is complete within 22 hr after egg lying (AEL) and neuromuscular junction (NMJ) formation begins at 13 hr AEL. At the time of initial synapse formation, DGluR-IIs appeared as clusters closely associated with some muscle nuclei. Subsequently, these nonjunctional clusters dispersed while DGluR-IIs accumulated at the junctional region. In a paralytic temperature-sensitive mutant,parats1,neural activity decreases drastically at restrictive temperatures. When neural activity was blocked throughout synaptogenesis by rearing embryos at a restrictive temperature prior to the beginning of synaptogenesis, 12 hr AEL, the dispersal of extrajunctional clusters was significantly suppressed and no accumulation of receptors at the junction was observed at 22 hr AEL. However, when neural activity was blocked later, by rearing embryos at a restrictive temperature from 13 hr AEL, DGluR-IIs did not accumulate at the NMJ, although extrajunctional clusters dispersed normally. These findings suggest that the neural activity differentially regulates dissipation of receptor clusters in the nonjunctional region and accumulation of receptors at the junctional region

Localization of Myosin and Actin in the Pelage and Whisker Hair Follicles of Rat

The combined effects of myosin II and actin enable muscle and nonmuscle cells to generate forces required for muscle contraction, cell division, cell migration, cellular morphological changes, the maintenance of cellular tension and polarity, and so on. However, except for the case of muscle contraction, the details are poorly understood. We focus on nonmuscle myosin and actin in the formation and maintenance of hair and skin, which include highly active processes in mammalian life with respect to the cellular proliferation, differentiation, and movement. The localization of nonmuscle myosin II and actin in neonatal rat dorsal skin, mystacial pad, hair follicles, and vibrissal follicles was studied by immunohistochemical technique to provide the basis for the elucidation of the roles of these proteins. Specificities of the antibodies were verified by using samples from the relevant tissues and subjecting them to immunoblotting test prior to morphological analyses. The myosin and actin were abundant and colocalized in the spinous and granular layers but scarce in the basal layer of the dorsal and mystacial epidermis. In hair and vibrissal follicles, nonmuscle myosin and actin were colocalized in the outer root sheath and some hair matrix cells adjoining dermal papillae. In contrast, most areas of the inner root sheath and hair matrix appeared to comprise very small amounts of myosin and actin. Hair shaft may comprise significant myosin during the course of its keratinization. These results suggest that the actin-myosin system plays a part in cell movement, differentiation, protection and other key functions of skin and hair cells

Immunohistochemical Localization of the Aquaporins AQP1, AQP3, AQP4, and AQP5 in the Mouse Respiratory System

Aquaporins are membrane water channel proteins that function mainly in water transfer across cellular membranes. In our present study, we investigated the immunohistochemical distribution of aquaporin 1 (AQP1), AQP3, AQP4, and AQP5 in the mouse respiratory system by immunofluorescence, immunoperoxidase, and immunoelectron microscopy. AQP3, AQP4, and AQP5 are expressed in epithelial cells, whereas AQP1 is expressed in subepithelial connective tissues and capillaries. In the airway surface epithelia from the nasal cavity to the intrapulmonary bronchioles, AQP5 was found to be mainly localized to the luminal side and both AQP3 and AQP4 to the abluminal side. In the alveolar epithelium, AQP5 is localized to the apical membranes of both type I and type II alveolar cells. Compared with the previous studies on the rat respiratory system, in which AQP5 is restricted to the alveolar type I cells and absent from the airway surface epithelia, we found that AQP5 in the mouse is much more widely distributed throughout the surface epithelia. These results suggest that AQP5 has a critical role in water-handling, such as the maintenance of airway surface liquid and clearance of alveolar fluid in the mouse respiratory system

Localization of Reversion-Induced LIM Protein (RIL) in the Rat Central Nervous System

Reversion-induced LIM protein (RIL) is a member of the ALP (actinin-associated LIM protein) subfamily of the PDZ/LIM protein family. RIL serves as an adaptor protein and seems to regulate cytoskeletons. Immunoblotting suggested that RIL is concentrated in the astrocytes in the central nervous system. We then examined the expression and localization of RIL in the rat central nervous system and compared it with that of water channel aquaporin 4 (AQP4). RIL was concentrated in the cells of ependyma lining the ventricles in the brain and the central canal in the spinal cord. In most parts of the central nervous system, RIL was expressed in the astrocytes that expressed AQP4. Double-labeling studies showed that RIL was concentrated in the cytoplasm of astrocytes where glial fibrillary acidic protein was enriched as well as in the AQP4-enriched regions such as the endfeet or glia limitans. RIL was also present in some neurons such as Purkinje cells in the cerebellum and some neurons in the brain stem. Differential expression of RIL suggests that it may be involved in the regulation of the central nervous system

Recent Advances in Fluorescent Labeling Techniques for Fluorescence Microscopy

Tremendous progress in recent computer-controlled systems for fluorescence and laser-confocal microscopy has provided us with powerful tools to visualize and analyze molecular events in the cells. Various fluorescent staining and labeling techniques have also been developed to be used with these powerful instruments. Fluorescent proteins such as green fluorescent protein (GFP) allow us to directly label particular proteins of interest in living cells. This technique has been extended over a large area of cell biology, and a variety of fluorescent protein-derived techniques have been developed to visualize the functions and conditions of the molecules within living cells. In this review, we summarize the techniques for fluorescent staining and labeling for recent fluorescence microscopy

Immunohistochemical Localization of the Water Channels AQP4 and AQP5 in the Rat Pituitary Gland

The pituitary gland is composed of the adenohypophysis and neurohypophysis. The adenohypophysis contains endocrine cells, folliculo-stellate (FS) cells, and marginal layer cells, whereas the neurohypophysis mainly comprises axons and pituicytes. To understand the molecular nature of water transfer in the pituitary gland, we examined the immunohistochemical localization of the membrane water channels aquaporin-4 (AQP4) and AQP5 in rat tissue. Double immunofluorescence analysis of AQP4 and S100 protein, a known marker for FS cells, marginal layer cells, and pituicytes, clearly revealed that FS cells and marginal layer cells in the adenohypophysis and the pituicytes in pars nervosa are positive for AQP4. AQP5 was found to be localized at the apical membrane in some marginal layer cells surrounding the Rathke’s residual pouch, in which AQP4 was observed to be localized on the basolateral membranes. These results suggest the following possibilities: 1) FS cells especially require water for their functions and 2) transepithelial water transfer could occur between the lumen of Rathke’s residual pouch and the interstitial fluid in the adenohypophysis through the AQP4 and AQP5 channels in the marginal layer cells

Palmitoylation of the canine histamine H2 receptor occurs at Cys305 and is important for cell surface targeting

AbstractTo determine the presence and functional role of the histamine H2 receptor (H2R) palmitoylation, a receptor with a Cys305 to Ala (A305 receptor) mutation was generated. Wild-type (WT) and A305 receptors were tagged at their N-termini with a hemagglutinin (HA) epitope. WT, but not A305, receptors incorporated [3H]palmitate by metabolic labeling, indicating that the H2R is palmitoylated at Cys305. Immunocytochemistry of WT and A305 receptors expressed in COS7 cells revealed WT receptors to be distributed at the plasma membrane, while the majority of A305 receptors were localized intracellularly with only a small portion being at the plasma membrane. However, the affinity of the A305 receptor for tiotidine was comparable to that of the WT receptor. In addition, when the amounts of cell surface receptors as determined by anti-HA antibody binding were equivalent, A305 receptors mediated production of more cAMP than WT receptors. Preincubation of COS7 cells expressing each receptor with 10−5 M histamine for 30 min reduced subsequent cAMP production in response to histamine via the receptors to similar extents, indicating that palmitoylation is not necessary for desensitization. In addition, cell surface A305 receptors were capable of being internalized from the cell surface at a rate and extent similar to those of WT receptors. Finally, CHO cell lines stably expressing either WT or A305 receptors were incubated with 10−5 M histamine for 1, 6, 12 and 24 h. Total amounts of WT and A305 receptors, as determined by tiotidine binding, were reduced by incubation, indicating downregulation. Downregulation of the A305 receptor was more extensive than that of the WT receptor. Thus, palmitoylation of the H2R might be important for targeting to the cell surface and stability

Post-progression survival and progression-free survival in patients with advanced hepatocellular carcinoma treated by sorafenib

Aim: Although sorafenib is a standard drug for advanced hepatocellular carcinoma (HCC), little is known about a patient\u27s clinical course after treatment. We investigated the effect of post-progression survival (PPS) and progression-free survival (PFS) on overall survival (OS) in patients whose advanced HCC was treated by sorafenib. Methods: We searched in the PubMed database for reports with survival data of patients with HCC treated with sorafenib monotherapy, and selected reports with 20 or more patients each that provided data for both OS and PFS or time to progression (TTP). Median PPS (mPPS) was defined as the period obtained by subtracting median PFS or TTP (mPFS/TTP) from median OS (mOS). We identified 56 reports with 5803 patients. We investigated the correlation of mOS and either mPPS or mPFS/TTP using weighted linear regression. Results: Median PPS correlated with mOS (r=0.834) very strongly, whereas mPFS/TTP did not correlate with mOS as highly as PPS did (r=0.546). When we stratified survival data by Child-Pugh classification, a significantly greater average percentage of mPPS to mOS was seen in Child-Pugh class A (54.4±17.6%) than in Child-Pugh class B (32.0±11.6%) (P=0.015). Conclusion: PPS highly correlated with OS, and its importance should be more emphasized for advanced HCC patients treated after sorafenib therapy, whereas we need to take more care in interpreting the results of PFS to evaluate treatment efficacy in clinical trials of advanced HCC. © 2015 The Japan Society of Hepatology.Embargo Period 12 month