Autism-associated mutations in the CaVß2 calcium-channel subunit increase Ba2+-currents and lead to differential modulation by the RGK-protein Gem.

Voltage-gated calcium-channels (VGCCs) are heteromers consisting of several subunits. Mutations in the genes coding for VGCC subunits have been reported to be associated with autism spectrum disorder (ASD). In a previous study, we identified electrophysiologically relevant missense mutations of CaVß2 subunits of VGCCs. From this, we derived the hypothesis that several CaVß2-mutations associated with ASD show common features sensitizing LTCCs and/or enhancing currents. Using a CaVß2d backbone, we performed extensive whole-cell and single-channel patch-clamp analyses of Ba2+ currents carried by Cav1.2 pore subunits co-transfected with the previously described CaVß2 mutations (G167S, S197F) as well as a recently identified point mutation (V2D). Furthermore, the interaction of the mutated CaVß2d subunits with the RGK protein Gem was analyzed by co-immunoprecipitation assays and electrophysiological studies. Patch-clamp analyses revealed that all mutations increase Ba2+ currents, e.g. by decreasing inactivation or increasing fraction of active sweeps. All CaVß2 mutations interact with Gem, but differ in the extent and characteristics of modulation by this RGK protein (e.g. decrease of fraction of active sweeps: CaVß2d_G167S > CaVß2d_V2D > CaVß2d_S197F). In conclusion, patch-clamp recordings of ASD-associated CaVß2d mutations revealed differential modulation of Ba2+ currents carried by CaV1.2 suggesting kind of an "electrophysiological fingerprint" each. The increase in current finally observed with all CaVß2d mutations analyzed might contribute to the complex pathophysiology of ASD and by this indicate a possible underlying molecular mechanism.

[The polypill in cardiovascular prevention: successful through simplification? : New study results on the benefit of the polypill strategy in primary and secondary prevention]. / "Polypill" in der kardiovaskulären Prävention ­ erfolgreich durch Vereinfachung? : Neue Studienergebnisse zum Nutzen der Polypill-Strategie in der Primär- und Sekundärprävention.

BACKGROUND: Cardiovascular disease is still the major cause of death worldwide. Beside the elevated blood pressure, a major modifiable risk factor is the elevated low-density lipoprotein (LDL) cholesterol. Although both risk factors are well manageable, therapeutic control remains poor with low adherence to medication being a major cause of insufficient treatment success. One solution to overcome this issue is the polypill concept, i.e. a combination of different drugs in one tablet. This not only increases adherence but also significantly improves patients' prognosis by reducing cardiovascular events. OBJECTIVE: This review focuses on current evidence published in randomized control trials in primary and secondary prevention. A major focus is on the recently published SECURE trial dealing with the polypill in secondary prevention. CURRENT DATA: Most trials dealing with the polypill concept focus on the control of risk factors such as blood pressure and LDL cholesterol while lacking a prognostic benefit in the form of a reduction in cardiovascular events. Recent trials such as the HOPE­3, PolyIran and TIPS­3 trials have shown a prognostic improvement for the polypill in primary prevention. In secondary prevention there has been a lack of prognostic benefit for the polypill to date. The recently published SECURE trial closed this gap by showing a significant reduction in major adverse cardiovascular events in post-infarct patients and also showing a reduction in cardiovascular death by 33%. CONCLUSION: The concept of the polypill has evolved from a comfort method for patients aimed at facilitating adherence to an innovative therapeutic concept with a proven prognostic advantage compared to current treatment practice by reducing cardiovascular events and mortality. Therefore, it is time to implement the concept of the polypill in primary and secondary prevention to improve patients' prognosis and reduce the burden of cardiovascular disease worldwide.

Inhibitory effects on L- and N-type calcium channels by a novel CaVß1 variant identified in a patient with autism spectrum disorder.

Voltage-gated calcium channel (VGCC) subunits have been genetically associated with autism spectrum disorders (ASD). The properties of the pore-forming VGCC subunit are modulated by auxiliary ß-subunits, which exist in four isoforms (CaVß1-4). Our previous findings suggested that activation of L-type VGCCs is a common feature of CaVß2 subunit mutations found in ASD patients. In the current study, we functionally characterized a novel CaVß1b variant (p.R296C) identified in an ASD patient. We used whole-cell and single-channel patch clamp to study the effect of CaVß1b_R296C on the function of L- and N-type VGCCs. Furthermore, we used co-immunoprecipitation followed by Western blot to evaluate the interaction of the CaVß1b-subunits with the RGK-protein Gem. Our data obtained at both, whole-cell and single-channel levels, show that compared to a wild-type CaVß1b, the CaVß1b_R296C variant inhibits L- and N-type VGCCs. Interaction with and modulation by the RGK-protein Gem seems to be intact. Our findings indicate functional effects of the CaVß1b_R296C variant differing from that attributed to CaVß2 variants found in ASD patients. Further studies have to detail the effects on different VGCC subtypes and on VGCC expression.

Depolarization induces nociceptor sensitization by CaV1.2-mediated PKA-II activation.

Depolarization drives neuronal plasticity. However, whether depolarization drives sensitization of peripheral nociceptive neurons remains elusive. By high-content screening (HCS) microscopy, we revealed that depolarization of cultured sensory neurons rapidly activates protein kinase A type II (PKA-II) in nociceptors by calcium influx through CaV1.2 channels. This effect was modulated by calpains but insensitive to inhibitors of cAMP formation, including opioids. In turn, PKA-II phosphorylated Ser1928 in the distal C terminus of CaV1.2, thereby increasing channel gating, whereas dephosphorylation of Ser1928 involved the phosphatase calcineurin. Patch-clamp and behavioral experiments confirmed that depolarization leads to calcium- and PKA-dependent sensitization of calcium currents ex vivo and local peripheral hyperalgesia in the skin in vivo. Our data suggest a local activity-driven feed-forward mechanism that selectively translates strong depolarization into further activity and thereby facilitates hypersensitivity of nociceptor terminals by a mechanism inaccessible to opioids.