ActionsCite Favorites Display options Display options Format 1 Department of Pharmacology and Toxicology, Center for Molecular Biosciences, University of Innsbruck, Innrain 80/82, 6020, Innsbruck, Austria. joerg.striessnig@uibk.ac.at. 2 Department of Pharmacology and Toxicology, Center for Molecular Biosciences, University of Innsbruck, Innrain 80/82, 6020, Innsbruck, Austria. 1 Department of Pharmacology and Toxicology, Center for Molecular Biosciences, University of Innsbruck, Innrain 80/82, 6020, Innsbruck, Austria. joerg.striessnig@uibk.ac.at. 2 Department of Pharmacology and Toxicology, Center for Molecular Biosciences, University of Innsbruck, Innrain 80/82, 6020, Innsbruck, Austria. Cav 1.3 belongs to the family of voltage-gated L-type Ca2+ channels and is encoded by the CACNA1D gene. Cav 1.3 channels are not only essential for cardiac pacemaking, hearing and hormone secretion but are also expressed postsynaptically in neurons, where they shape neuronal firing and plasticity. Recent findings provide evidence that human mutations in the CACNA1D gene can confer risk for the development of neuropsychiatric disease and perhaps also epilepsy. Loss of Cav 1.3 function, as shown in knock-out mouse models and by human mutations, does not result in neuropsychiatric or neurological disease symptoms, whereas their acute selective pharmacological activation results in a depressive-like behaviour in mice. Therefore it is likely that CACNA1D mutations enhancing activity may be disease relevant also in humans. Indeed, whole exome sequencing studies, originally prompted to identify mutations in primary aldosteronism, revealed de novo CACNA1D missense mutations permitting enhanced Ca2+ signalling through Cav 1.3. Remarkably, apart from primary aldosteronism, heterozygous carriers of these mutations also showed seizures and neurological abnormalities. Different missense mutations with very similar gain-of-function properties were recently reported in patients with autism spectrum disorders (ASD). These data strongly suggest that CACNA1D mutations enhancing Cav 1.3 activity confer a strong risk for - or even cause - CNS disorders, such as ASD. © 2016 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society. A, CACNA1D missense mutations are illustrated by circles. Somatic missense mutations identified in APAs are highlighted in red (Azizan et al. 2013; Scholl et al. 2013; Fernandes‐Rosa et al. 2014; Akerstrom et al. 2015; Nishimoto et al. 2015; Wang et al. 2015; Scholl et al. 2015 a). So far, only mutations V259D, G403D/R, I750M and P1336R have been functionally characterized, and they show strong gain‐of‐function phenotypes (Azizan et al. 2013; Scholl et al. 2013). G403R and I750M were also identified as de novo germline mutations in two patients with primary aldosteronism, seizures and neurological abnormalities (PASNA), highlighted in blue (Scholl et al. 2013). Mutations identified in individuals with ASD are shown in green. Mutations G407R (exon 8a), A749G and V584I were identified in the affected individuals but absent in parents or unaffected siblings and therefore classified as de novo (Iossifov et al. 2012; O\'Roak et al. 2012; De Rubeis et al. 2014). Mutations A59V, S1953L and R1997H were detected in a case‐control sample (De Rubeis et al. 2014). Mutations G407R and A749G have been characterized and show a pronounced gain‐of‐function (Fig. 2, Pinggera et al. 2015). B, alignment of amino acid sequence of transmembrane S6‐helices of repeats I and II containing the activation gates at their cytoplasmic ends. They are highly conserved among α1 subunits of the L‐type Ca2+ channel family. Cav1.3 undergoes alternative splicing in the activation gate of repeat I (exons 8a vs. 8b) (Baig et al. 2011). Positions mutated in ASD and PASNA are located in close proximity to each other as indicated in the alignment. Whereas ASD‐linked mutation G407R only occurs in exon 8a (Pinggera et al. 2015), G403D was identified in both exons in APAs but was present in exon 8b in PASNA (Scholl et al. 2013). (Alignment was performed by ClustalW using the following reference sequences: Cav1.3 EU363339, Cav1.1 Q02789, Cav1.2 NP_001153005.1, Cav1.4 Q9JIS7; conserved residues are highlighted in grey.) Figure 2. Gating changes induced by missense mutations A749G (ASD) vs . I750M (PASNA, APA) Figure 2. Gating changes induced by missense mutations A749G (ASD) vs. I750M (PASNA, APA) Mutations were introduced into the long isoform of Cav1.3 α1 subunits and heterologously expressed in tsA‐201 cells together with auxiliary α2δ‐1 and β3 subunits. The biophysical characterization of the mutants was performed by whole‐cell patch‐clamp recordings with 15 mm Ca2+ as charge carrier. A, steady state activation (circles) and inactivation (squares). Data shown as the mean ± SEM. Mutation A749G (n = 27) shifted voltage dependence of activation by 10 mV to more negative potentials in comparison to wild‐type (WT, n = 29). Mutation I750M (n = 11) resulted in an even stronger change (−15 mV shift compared to WT). In addition, A749G (n = 14) shifted steady state inactivation (measured after 5 s conditioning pulses to the indicated voltages) by 15 mV to more negative potential compared to WT (n = 18). This shift was less pronounced for I750M (−8 mV, n = 9). B, ICa inactivation upon 5 s depolarization to V max. Traces shown as the mean ± SEM. In contrast to I750M (n = 9) mutation A749G (n = 6) showed a more pronounced inactivation compared to WT (n = 15). The reduced inactivation of I750M is also evident in A. C, representative ICa traces upon depolarization to the reversal potential (V rev) normalized to the area of the ON‐gating charge movement (Q ON, as a measure of functional channels on the cell surface). Mutations A749G (upper panel, green) and I750M (lower panel blue) showed increased tail amplitudes when normalized to Q ON in comparison to WT (black), suggesting higher channel open probability or conductance. Modified from Azizan et al. (2013), I750M, and Pinggera et al. (2015), WT and A749G). Pinggera A, Mackenroth L, Rump A, Schallner J, Beleggia F, Wollnik B, Striessnig J. Pinggera A, et al. Hum Mol Genet. 2017 Aug 1;26(15):2923-2932. doi: 10.1093/hmg/ddx175. Hum Mol Genet. 2017. PMID: 28472301 Free PMC article. Pinggera A, Lieb A, Benedetti B, Lampert M, Monteleone S, Liedl KR, Tuluc P, Striessnig J. Pinggera A, et al. Biol Psychiatry. 2015 May 1;77(9):816-22. doi: 10.1016/j.biopsych.2014.11.020. Epub 2014 Dec 8. Biol Psychiatry. 2015. PMID: 25620733 Free PMC article. Hofer NT, Tuluc P, Ortner NJ, Nikonishyna YV, Fernándes-Quintero ML, Liedl KR, Flucher BE, Cox H, Striessnig J. Hofer NT, et al. Mol Autism. 2020 Jan 8;11(1):4. doi: 10.1186/s13229-019-0310-4. eCollection 2020. Mol Autism. 2020. PMID: 31921405 Free PMC article. Ortner NJ, et al. Pflugers Arch. 2020 Jul;472(7):755-773. doi: 10.1007/s00424-020-02418-w. Epub 2020 Jun 24. Pflugers Arch. 2020. PMID: 32583268 Free PMC article. Review. Gualdani R, Yuan JH, Effraim PR, Di Stefano G, Truini A, Cruccu G, Dib-Hajj SD, Gailly P, Waxman SG. Gualdani R, et al. Neurol Genet. 2021 Jan 11;7(1):e550. doi: 10.1212/NXG.0000000000000550. eCollection 2021 Feb. Neurol Genet. 2021. PMID: 33977138 Free PMC article. Hofer NT, Pinggera A, Nikonishyna YV, Tuluc P, Fritz EM, Obermair GJ, Striessnig J. Hofer NT, et al. Channels (Austin). 2021 Dec;15(1):38-52. doi: 10.1080/19336950.2020.1859260. Channels (Austin). 2021. PMID: 33380256 Free PMC article. Fan P, et al. 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