In JoVE (1)
Articles by Claudia Sagheddu in JoVE
Flash fotolyse van Gekooide verbindingen in de Cilia van olfactorische sensorische neuronen Anna Boccaccio1,2, Claudia Sagheddu1, Anna Menini1,3 1SISSA, International School for Advanced Studies, 2Istituto di Biofisica, Consiglio Nazionale delle Ricerche, 3SISSA Unit, Italian Institute of Technology Fotolyse van gekooide verbindingen maakt de productie van snelle en gelokaliseerde toename van de concentratie van diverse fysiologisch actieve verbindingen. Hier laten we zien hoe de patch-clamp opnames gecombineerd met fotolyse van gekooide cAMP of gekooid Ca voor de studie van olfactorische transductie in gedissocieerde muis olfactorische sensorische neuronen te verkrijgen.
Other articles by Claudia Sagheddu on PubMed
Calcium-activated Chloride Currents in Olfactory Sensory Neurons from Mice Lacking Bestrophin-2 The Journal of Physiology. Sep, 2009 | Pubmed ID: 19622610 Olfactory sensory neurons use a chloride-based signal amplification mechanism to detect odorants. The binding of odorants to receptors in the cilia of olfactory sensory neurons activates a transduction cascade that involves the opening of cyclic nucleotide-gated channels and the entry of Ca(2+) into the cilia. Ca(2+) activates a Cl(-) current that produces an efflux of Cl(-) ions and amplifies the depolarization. The molecular identity of Ca(2+)-activated Cl(-) channels is still elusive, although some bestrophins have been shown to function as Ca(2+)-activated Cl(-) channels when expressed in heterologous systems. In the olfactory epithelium, bestrophin-2 (Best2) has been indicated as a candidate for being a molecular component of the olfactory Ca(2+)-activated Cl(-) channel. In this study, we have analysed mice lacking Best2. We compared the electrophysiological responses of the olfactory epithelium to odorant stimulation, as well as the properties of Ca(2+)-activated Cl(-) currents in wild-type (WT) and knockout (KO) mice for Best2. Our results confirm that Best2 is expressed in the cilia of olfactory sensory neurons, while odorant responses and Ca(2+)-activated Cl(-) currents were not significantly different between WT and KO mice. Thus, Best2 does not appear to be the main molecular component of the olfactory channel. Further studies are required to determine the function of Best2 in the cilia of olfactory sensory neurons.
Calcium Concentration Jumps Reveal Dynamic Ion Selectivity of Calcium-activated Chloride Currents in Mouse Olfactory Sensory Neurons and TMEM16b-transfected HEK 293T Cells The Journal of Physiology. Nov, 2010 | Pubmed ID: 20837642 Ca(2+)-activated Cl(-) channels play relevant roles in several physiological processes, including olfactory transduction, but their molecular identity is still unclear. Recent evidence suggests that members of the transmembrane 16 (TMEM16, also named anoctamin) family form Ca(2+)-activated Cl(-) channels in several cell types. In vertebrate olfactory transduction, TMEM16b/anoctamin2 has been proposed as the major molecular component of Ca(2+)-activated Cl(-) channels. However, a comparison of the functional properties in the whole-cell configuration between the native and the candidate channel has not yet been performed. In this study, we have used the whole-cell voltage-clamp technique to measure functional properties of the native channel in mouse isolated olfactory sensory neurons and compare them with those of mouse TMEM16b/anoctamin2 expressed in HEK 293T cells. We directly activated channels by rapid and reproducible intracellular Ca(2+) concentration jumps obtained from photorelease of caged Ca(2+) and determined extracellular blocking properties and anion selectivity of the channels. We found that the Cl(-) channel blockers niflumic acid, 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) and DIDS applied at the extracellular side of the membrane caused a similar inhibition of the two currents. Anion selectivity measured exchanging external ions and revealed that, in both types of currents, the reversal potential for some anions was time dependent. Furthermore, we confirmed by immunohistochemistry that TMEM16b/anoctamin2 largely co-localized with adenylyl cyclase III at the surface of the olfactory epithelium. Therefore, we conclude that the measured electrophysiological properties in the whole-cell configuration are largely similar, and further indicate that TMEM16b/anoctamin2 is likely to be a major subunit of the native olfactory Ca(2+)-activated Cl(-) current.