Early upregulation in nasal epithelium and strong expression in olfactory bulb glomeruli suggest a role for Aquaporin-4 in olfaction

Aquaporin-4 (AQP4) has been reported to be upregulated post-partum in pregnancy and in early lung development. Several technical challenges exist in measuring AQP4 protein levels, among them sensitivity to detergent solubilization, sample heating and gel composition. Here we have optimized quantification of AQP4 using immuno-blots. Using improved methodology we find no evidence for AQP4 upregulation post-partum or in the early lung development. However, in the nasal epithelium AQP4 is upregulated as early as in the brain. Furthermore, AQP4 is strongly expressed in the glomerulus, the synaptic unit of the olfactory bulb, suggesting a role for AQP4 in olfactory function.     

Aquaporin pathways and mucin secretion of Bowman's glands might protect the olfactory mucosa

The sense of smell is conveyed by the olfactory sensory neurons of the olfactory mucosa. Uniquely for sensory systems, the olfactory neurons directly face the external environment and are thus vulnerable to infections and changes in the airway surface liquid, but the surface liquid production and maintenance is not well understood. Here we show in rats and mice that Bowman's glands secrete the mucin MUC5AC. Aquaporin-5 was present at the apical face of the olfactory epithelium, completing a water transport pathway to the surface of the epithelium. Immunogold electron microscopy analysis revealed an intricate network of fine Aquaporin-1-positive fibroblast processes that surround Bowman's glands, whereas deeper blood vessels were unlabeled for Aquaporin-1. Our results show how the olfactory mucosa might be protected against infections and dehydration generally and how neuronal function is protected against ion concentration changes in the airway surface liquid by rapid replacement of water losses through the aquaporin pathways.     

Microbial growth studies in biodiesel blends

Introduction of biofuels to the fuel matrix poses new questions and challenges. The present study investigates the microbiological stability of biodiesel blends in small scale microcosms. The study presents results from incubations of diesel-biodiesel blends with contaminated inoculation water collected from diesel storage tanks to ensure the presence of relevant fuel degrading bacteria. DAPI and qPCR analyses has subsequently shown an increased bacterial growth and activity in the microcosms containing biodiesel blends as the carbon source compared to those microcosms where neat fossil diesel made up the carbon source. Several anaerobic microorganisms have been identified after incubation. Presence of methanogens, sulfate-reducing bacteria and nitrate reducing bacteria has furthermore been confirmed by chemical analyses, supplemented by observations of methane formation in biodiesel incubations. The findings will contribute to the knowledge base for a safer introduction of biodiesel in the fuel matrix by employment of proper house-keeping and monitoring methods.     

Nonlinear analysis of motor activity shows differences between schizophrenia and depression: a study using Fourier analysis and sample entropy

The purpose of this study has been to describe motor activity data obtained by using wrist-worn actigraphs in patients with schizophrenia and major depression by the use of linear and non-linear methods of analysis. Different time frames were investigated, i.e., activity counts measured every minute for up to five hours and activity counts made hourly for up to two weeks. The results show that motor activity was lower in the schizophrenic patients and in patients with major depression, compared to controls. Using one minute intervals the depressed patients had a higher standard deviation (SD) compared to both the schizophrenic patients and the controls. The ratio between the root mean square successive differences (RMSSD) and SD was higher in the schizophrenic patients compared to controls. The Fourier analysis of the activity counts measured every minute showed that the relation between variance in the low and the high frequency range was lower in the schizophrenic patients compared to the controls. The sample entropy was higher in the schizophrenic patients compared to controls in the time series from the activity counts made every minute. The main conclusions of the study are that schizophrenic and depressive patients have distinctly different profiles of motor activity and that the results differ according to period length analysed.     

The kinetochore protein Cenp‐F is a potential novel target for zoledronic acid in breast cancer cells

The anti‐resorptive agent zoledronic acid inhibits key enzymes in the mevalonate pathway, disrupting post‐translational modification and thereby correct protein localization and function. Inhibition of prenylation may also be responsible for the reported anti‐tumour effects of zoledronic acid, but the specific molecular targets have not been identified. Cenp‐F/mitosin, a kinetochore‐associated protein involved in the correct separation of chromosomes during mitosis, has been shown to undergo post‐translational prenylation and may therefore be a novel target contributing to the anti‐tumour effects of zoledronic acid. We investigated whether zoledronic acid causes loss of Cenp‐F from the kinetochore in breast cancer cells, to determine if the reported anti‐tumour effects may be mediated by impairing correct chromosome separation. MDA‐MB‐436, MDA‐MB‐231 and MCF‐7 breast cancer cells and MCF‐10A non‐malignant breast epithelial cells were treated with zoledronic acid in vitro, and the effect on Cenp‐F localization was analysed by immunoflourescence microscopy. Zoledronic acid caused loss of Cenp‐F from the kinetochore, accompanied by an increase in the number of cells in pro‐, /prometa‐ and metaphase in all of the cancer cell lines. There was also a significant increase in the number of lagging chromosomes in mitotic cells. The effects of zoledronic acid could be reversed by inclusion of an intermediary of the mevalonate pathway, showing that the loss of Cenp‐F from the kinetochore was caused by the inhibition of farnesylation. In contrast, no effect was seen on Cenp‐F in non‐malignant MCF‐10A cells. This is the first report showing a specific effect of zoledronic acid on a protein involved in the regulation of chromosome segregation, identifying Cenp‐F as a potential new molecular target for NBPs in tumour cells.     

Pathophysiological roles of osteoprotegerin (OPG)

Osteoprotegerin (OPG) is a secreted glycoprotein central to bone turnover via its role as a decoy receptor for the receptor activator of nuclear factor kappaB ligand (RANKL) and has traditionally been linked to a number of bone-related diseases. However, there is additional evidence that OPG can promote cell survival by inhibiting TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. As a result, a number of in vitro, in vivo and clinical studies have been performed assessing the role of OPG in tumourigenesis. Similar studies have been performed regarding vascular pathologies, resulting from observations of expression and regulation of OPG in the vasculature. This review aims to provide an update on this area and assess the potential protective or detrimental role of OPG in both vascular pathologies and tumourigenesis.     

Epsin 1 is Involved in Recruitment of Ubiquitinated EGF Receptors into Clathrin-Coated Pits

Epsin consists of an epsin NH₂-terminal homology domain that promotes interaction with phospholipids, several AP-2-binding sites, two clathrin-binding sequences and several Eps15 homology domain-binding motifs. Epsin additionally possesses ubiquitin-interacting motifs (UIMs) and has been demonstrated to bind ubiquitinated cargo. We therefore investigated whether epsin promoted clathrin-mediated endocytosis of the ubiquitinated EGF receptor (EGFR). By immunoprecipitation, we found that epsin 1 interacted with ubiquitinated EGFR and that functional UIMs were essential for complex formation. Furthermore, RNA interference-mediated knockdown of epsin 1 was found to inhibit internalization of the EGFR, while having no effect on endocytosis of the transferrin receptor. Additionally, upon knockdown of epsin 1, translocation of the EGFR to central parts of clathrin-coated pits was inhibited. This supports the contention that epsin 1 promotes endocytosis of the ubiquitinated EGFR.