No abstract

Reduced olfactory acuity is prevalent post-laryngectomy. Olfactory acuity can be significantly improved using either 6 weeks of clinician-assisted or home practice using the NAIM manoeuvre, although the current data suggest that intensive clinician-assisted treatment can assist patients to improve more rapidly and have a positive impact on functional state.

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The voltage-gated L-type Ca2+ channel CaV1.2 is crucial for initiating heartbeat and control of a number of neuronal functions such as neuronal excitability and long-term potentiation. Mutations of CaV1.2 subunits result in serious health problems including arrhythmia, autism spectrum disorders, immunodeficiency, and hypoglycemia. Thus precise control of CaV1.2 surface expression and localization is essential. We previously reported that α-actinin associates and colocalizes with neuronal CaV1.2 channels and that shRNA-mediated depletion of α-actinin significantly reduces localization of endogenous CaV1.2 in dendritic spines in hippocampal neurons. Here we investigated the hypothesis that direct binding of α-actinin to CaV1.2 supports its surface expression. Using two-hybrid screens and pull-down assays we identified three point mutations (K1647A, Y1649A, and I1654A) in the central, pore-forming α11.2 subunit of CaV1.2 that individually impaired α-actinin binding. Surface biotinylation and flow cytometry assays revealed that CaV1.2 channels composed of the corresponding α-actinin-binding-deficient mutants results in a 35–40% reduction in surface expression compared to wild-type channels. Moreover, the mutant CaV1.2 channels expressed in HEK293 cells exhibit a 60–75% reduction in current density. The larger decrease in current density as compared to surface expression imparted by these α11.2 subunit mutations hints at the possibility that α-actinin not only stabilizes surface localization of CaV1.2 but also augments its ion conducting activity.