Role of a conserved glutamine in the function of voltage-gated Ca2+ channels revealed by a mutation in human CACNA1D

Abstract

Voltage-gated Ca Ca channels play crucial roles in regulating gene transcription, neuronal excitability, and synaptic transmission. Natural or pathological variations in Ca channels have yielded rich insights into the molecular determinants controlling channel function. Here, we report the consequences of a natural, putatively disease-associated mutation in the gene encoding the pore-forming Ca1.3 α subunit. The mutation causes a substitution of a glutamine residue that is highly conserved in the extracellular S1-S2 loop of domain II in all Ca channels with a histidine and was identified by whole-exome sequencing of an individual with moderate hearing impairment, developmental delay, and epilepsy. When introduced into the rat Ca1.3 cDNA, Q558H significantly decreased the density of Ca currents in transfected HEK293T cells. Gating current analyses and cell-surface biotinylation experiments suggested that the smaller current amplitudes caused by Q558H were because of decreased numbers of functional Ca1.3 channels at the cell surface. The substitution also produced more sustained Ca currents by weakening voltage-dependent inactivation. When inserted into the corresponding locus of Ca2.1, the substitution had similar effects as in Ca1.3. However, the substitution introduced in Ca3.1 reduced current density, but had no effects on voltage-dependent inactivation. Our results reveal a critical extracellular determinant of current density for all Ca family members and of voltage-dependent inactivation of Ca1.3 and Ca2.1 channels.

Constitutive activity of dopamine receptor type 1 (D1R) increases CaV2.2 currents in PFC neurons

“…7 A ). To demonstrate that the Q ON increase is not due to changes in the relative open probability, we plotted raw Q ON values versus peak tail current for individual cells ( Wei et al, 1994 ; Jones et al, 1999 ; Takahashi et al, 2004 ; Garza-Lopez et al, 2018 ) and found that the parameters from the lineal regression fits for control cells (−D1R) and cells coexpressing D1R (+D1R) are not different ( Fig. 7 B ).…”

Biophysical classification of a CACNA1D de novo mutation as a high-risk mutation for a severe neurodevelopmental disorder

“…In this study, we provide compelling evidence for the CACNA1D S652L variant as a high-risk and likely disease-causing mutation in two individuals of the Deciphering Developmental Disorders cohort (decipher.sanger.ac.uk) of children with severe, undiagnosed developmental disorders [23]. This evidence builds on a detailed biophysical characterization that demonstrates gating changes able to also induce enhanced channel activity as is typical for six other de novo germline missense mutations in patients with ASD with and without other neurodevelopmental symptoms [14][15][16][17][18]20]. Our data adds the CACNA1D gene to the other 12 developmental-disorder-linked genes identified in the Deciphering Developmental Disorders study and thus further increases its diagnostic yield.…”

“…others [17,18,20,38] in a total of seven patients with neurodevelopmental disorders. Functionally they fall into two major classes.…”

“…We [14][15][16] and others [17][18][19][20] have recently provided accumulating evidence that de novo missense mutations in the pore-forming α 1 -subunit of Cav1.3 LTCCs (CACNA1D) confer high risk for neurodevelopmental disorders in humans. Symptoms range from ASD with (mutations A749G, Q547H [14,20];) and without (G407R [14]) intellectual disability to more severely affected patients with seizures, muscle hypotonia, and global developmental delay (V401L [15]). Some patients also exhibit additional endocrine symptoms (primary aldosteronism or hyperinsulinism; G403D, I750M [17,18]) due to the expression of Cav1.3 in adrenal zona glomerulosa cells and pancreatic β-cells (for a review, see [3]).…”

Genetic Associations between Voltage-Gated Calcium Channels and Psychiatric Disorders

“…Interestingly alterations in the relative abundance of several alternatively spliced exons in CACNA1D have been observed cortical samples of patients with ASD [205]. Finally, the variation Q567H is linked to moderate hearing impairment and intellectual disability, this variation results in a loss of function [206].…”