Inhibitory effects on L- and N-type calcium channels by a novel CaV\u03b21 variant identified in a patient with autism spectrum disorder

Patrick Despang,Alexandra Breitenkamp,Jan Matthes,Sarah Salamon,Elza Kuzmenkina

doi:10.1007/s00210-022-02213-7

Patrick Despang, Alexandra Breitenkamp + Show 3 more

Open Access

https://doi.org/10.1007/s00210-022-02213-7

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Abstract

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 β-subunits, which exist in four isoforms (CaVβ1-4). Our previous findings suggested that activation of L-type VGCCs is a common feature of CaVβ2 subunit mutations found in ASD patients. In the current study, we functionally characterized a novel CaVβ1b variant (p.R296C) identified in an ASD patient. We used whole-cell and single-channel patch clamp to study the effect of CaVβ1b_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 CaVβ1b-subunits with the RGK-protein Gem. Our data obtained at both, whole-cell and single-channel levels, show that compared to a wild-type CaVβ1b, the CaVβ1b_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 CaVβ1b_R296C variant differing from that attributed to CaVβ2 variants found in ASD patients. Further studies have to detail the effects on different VGCC subtypes and on VGCC expression.

Highlights

Autism spectrum disorder (ASD) is a complex neuro-developmental disorder and affects about 1% of the population worldwide (Won et al 2013)
Since the discovery that a single point mutation in the α1-subunit of L-type calcium channels (CaV1.2) causes Timothy syndrome, many other genes encoding voltage-gated calcium channel (VGCC) subunits have been associated with ASD
We report here the identification and first electrophysiological characterization of C aVβ1b_R296C, a novel variant of the β1-isoform of VGCC subunits found in an ASD patient

Summary

Introduction

Autism spectrum disorder (ASD) is a complex neuro-developmental disorder and affects about 1% of the population worldwide (Won et al 2013). In ASD, the wide range of genetic findings points to various signaling pathways involved in the manifestation of this disorder (O’Roak et al 2011; Ebert and Greenberg 2013). Since the discovery that a single point mutation in the α1-subunit of L-type calcium channels (CaV1.2) causes Timothy syndrome, many other genes encoding voltage-gated calcium channel (VGCC) subunits have been associated with ASD. High-voltage activated VGCCs are heteromers composed of up to four subunits (CaVα1, CaVβ, CaVα2-δ, CaVγ) (Buraei and Yang 2010; Campiglio and Flucher 2015). CaVβ-subunits consist of five domains: a variable N-terminus, a conserved Src homology 3 domain (SH3), a conserved but alternatively spliced HOOK domain, a guanylate kinase domain (GK), and a variable C-terminus (Buraei and Yang 2010). With the exception of some rare splice variants, all C aVβ-subunits have the same functional structure and show a significant

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