Abstract:At least 5% of individuals with hypertension have adrenal aldosterone-producing adenomas (APAs). Gain-of-function mutations in KCNJ5 and apparent loss-of-function mutations in ATP1A1 and ATP2A3 were reported to occur in APAs. We find that KCNJ5 mutations are common in APAs resembling cortisol-secreting cells of the adrenal zona fasciculata but are absent in a subset of APAs resembling the aldosterone-secreting cells of the adrenal zona glomerulosa. We performed exome sequencing of ten zona glomerulosa-like APA… Show more
“…As evident from the current traces in Figure 4(a) (inset, arrows), in 27 out of 30 recordings the Q ON voltage sensor movement, which is present in WT L in all cells, was not detectable. We have obtained a similar decrease in Q ON relative to ionic current previously for APA mutations I750M, V259D and P1336R [11] and ASD mutation A749G [10] when introduced into the long splice variant. Taken together, F747L L exhibits the typical gating changes observed for previously studied mutations clearly identifying this mutation as the cause for excess aldosterone production in APAs.10.1080/19336950.2018.1546518-F0004Figure 4.Biophysical properties of Ca v 1.3 mutant F747L L. (a) Current-voltage relationships ( I Ca , mean ± S.E.M.)…”
Section: Resultssupporting
confidence: 77%
“…Here we report the analysis of three APA mutations (F747L, R990H, M1354I) which we have previously reported together with other C ACNA1D mutations in a cohort of 152 subjects [11]. We also investigated if alternative splicing of Ca v 1.3 α1 can affect mutational effects on channel function in R990H, M1354I and in two previously reported ASD mutations A749G and G407R.…”
Section: Introductionmentioning
confidence: 92%
“…Therefore, newly identified rare missense variants have to be functionally characterized in heterologous expression systems to confirm their disease causing potential. So far this has been accomplished for seven patients with germline CACNA1D mutations [six different mutations, 9,10,13–15] and six somatic mutations occurring in APAs [11,12,15,21]. Interestingly, several of the functionally verified germline mutations causing a neurodevelopmental disorder are also found in APAs [I750M, G403D, V401L, 18].…”
Recently, we and others identified somatic and germline de novo gain-of-function mutations in CACNA1D, the gene encoding the α1-subunit of voltage-gated Cav1.3 Ca2+-channels. While somatic mutations identified in aldosterone producing adenomas (APAs) underlie treatment-resistant hypertension, germline CACNA1D mutations are associated with a neurodevelopmental disorder characterized by a wide symptomatic spectrum, including autism spectrum disorder. The number of newly identified CACNA1D missense mutations is constantly growing, but their pathogenic potential is difficult to predict in silico, making functional studies indispensable to assess their contribution to disease risk.Here we report the functional characterization of previously identified CACNA1D APA mutations F747L and M1354I using whole-cell patch-clamp electrophysiology upon recombinant expression in tsA-201 cells. We also investigated if alternative splicing of Cav1.3 affects the aberrant gating of the previously characterized APA mutation R990H and two mutations associated with autism spectrum disorder (A479G and G407R). Splice-variant dependent gating changes are of particular interest for germline mutations, since the relative expression of Cav1.3 splice variants differs across different tissues and within brain regions and might therefore result in tissue-specific phenotypes. Our data revealed a complex gain-of-function phenotype for APA mutation F747L confirming its pathogenic role. Furthermore, we found splice-variant dependent gating changes in R990H, A749G and G407R. M1354I did not change channel function of Cav1.3 splice variants and should therefore be considered a rare non-pathogenic variant until further proof for its pathogenicity is obtained. Our new findings together with previously published data allow classification of pathogenic CACNA1D mutations into four categories based on prototypical functional changes.
“…As evident from the current traces in Figure 4(a) (inset, arrows), in 27 out of 30 recordings the Q ON voltage sensor movement, which is present in WT L in all cells, was not detectable. We have obtained a similar decrease in Q ON relative to ionic current previously for APA mutations I750M, V259D and P1336R [11] and ASD mutation A749G [10] when introduced into the long splice variant. Taken together, F747L L exhibits the typical gating changes observed for previously studied mutations clearly identifying this mutation as the cause for excess aldosterone production in APAs.10.1080/19336950.2018.1546518-F0004Figure 4.Biophysical properties of Ca v 1.3 mutant F747L L. (a) Current-voltage relationships ( I Ca , mean ± S.E.M.)…”
Section: Resultssupporting
confidence: 77%
“…Here we report the analysis of three APA mutations (F747L, R990H, M1354I) which we have previously reported together with other C ACNA1D mutations in a cohort of 152 subjects [11]. We also investigated if alternative splicing of Ca v 1.3 α1 can affect mutational effects on channel function in R990H, M1354I and in two previously reported ASD mutations A749G and G407R.…”
Section: Introductionmentioning
confidence: 92%
“…Therefore, newly identified rare missense variants have to be functionally characterized in heterologous expression systems to confirm their disease causing potential. So far this has been accomplished for seven patients with germline CACNA1D mutations [six different mutations, 9,10,13–15] and six somatic mutations occurring in APAs [11,12,15,21]. Interestingly, several of the functionally verified germline mutations causing a neurodevelopmental disorder are also found in APAs [I750M, G403D, V401L, 18].…”
Recently, we and others identified somatic and germline de novo gain-of-function mutations in CACNA1D, the gene encoding the α1-subunit of voltage-gated Cav1.3 Ca2+-channels. While somatic mutations identified in aldosterone producing adenomas (APAs) underlie treatment-resistant hypertension, germline CACNA1D mutations are associated with a neurodevelopmental disorder characterized by a wide symptomatic spectrum, including autism spectrum disorder. The number of newly identified CACNA1D missense mutations is constantly growing, but their pathogenic potential is difficult to predict in silico, making functional studies indispensable to assess their contribution to disease risk.Here we report the functional characterization of previously identified CACNA1D APA mutations F747L and M1354I using whole-cell patch-clamp electrophysiology upon recombinant expression in tsA-201 cells. We also investigated if alternative splicing of Cav1.3 affects the aberrant gating of the previously characterized APA mutation R990H and two mutations associated with autism spectrum disorder (A479G and G407R). Splice-variant dependent gating changes are of particular interest for germline mutations, since the relative expression of Cav1.3 splice variants differs across different tissues and within brain regions and might therefore result in tissue-specific phenotypes. Our data revealed a complex gain-of-function phenotype for APA mutation F747L confirming its pathogenic role. Furthermore, we found splice-variant dependent gating changes in R990H, A749G and G407R. M1354I did not change channel function of Cav1.3 splice variants and should therefore be considered a rare non-pathogenic variant until further proof for its pathogenicity is obtained. Our new findings together with previously published data allow classification of pathogenic CACNA1D mutations into four categories based on prototypical functional changes.
“…L'équilibre ionique au centre de la pathogenèse des adénomes produisant de l'aldostérone Mutations du gène codant le canal ionique KCNJ5 La comparaison, chez un même patient, des séquences d'exomes de l'ADN constitutionnel et de l'ADN (ADN somatique) extrait d'adénomes produisant de l'aldostérone a permis d'identifier des mutations somatiques récurrentes dans des gènes codant des canaux ioniques (KCNJ5 2 [8] et CACNA1D 3 [9,10]) et des ATPases (ATP1A1 et ATP2B3 [11]) impliqués dans la régulation de l'homéostasie ionique intracellulaire et du potentiel de membrane (Figure 1). Il est à noter qu'aucune mutation germinale n'a été identifiée chez des patients ayant un adé-nome porteur de mutations somatiques.…”
Section: Revuesunclassified
“…Cela déclenche l'ouverture de canaux Ca 2+ dépendants du voltage et l'activation de la voie de signalisation calcique, stimulant la production d'aldostérone. La surexpression de différents canaux mutés dans une lignée cellulaire de cortex surrénalien induit une augmentation de l'expression de CYP11B2 et de la production d'aldostérone, ainsi que de celle de deux des régulateurs transcriptionnels de CYP11B2, NURR1 (nuclear receptor related 1 [9,10]. Les mutations de la sous-unité 1 de la Na + ,K + -ATPase affectent des résidus particuliers localisés au niveau des hélices transmembranaires M1 et M4 de la protéine, et impliqués dans l'interaction avec le Na + et/ou le K + .…”
Voltage‐gated calcium channels (VGCCs) open as a result of plasma membrane depolarisation. When open, they allow Ca
2+
ions to pass down their electrochemical gradient. Different VGCCs can be distinguished both physiologically and pharmacologically in native tissues. There are ten mammalian genes encoding Ca
2+
channel α
1
subunits, and these map well on to the endogenous channels identified by electrophysiological studies. The subunit composition of the channel complexes, and the role of the auxiliary subunits, is also discussed. Information from structure–function studies and from structural biology is able to provide insight into the mechanism of action of these channels, for example regarding gating and ion selectivity. The different channels have widely divergent tissue distributions and their distinctive individual properties allow them to fulfil many and varied functions. There are also several forms of second messenger‐mediated modulation of the different channels, including regulation by G proteins and by Ca
2+
‐calmodulin.
Key Concepts
VGCCs, when open, allow Ca
2+
ions to pass down their electrochemical gradient.
Opening of VGCCs occurs in response to membrane depolarisation sensed by the S4 voltage sensors.
The exquisite selectivity of VGCCs for Ca
2+
is a result of the presence of four glutamate (or aspartate) residues in the selectivity filter of the pore, whose side chains coordinate Ca
2+
.
VGCCs are usually complexes of multiple subunits: α
1
, which comprises the channel itself, associated with auxiliary subunits, α
2
δ and β. A γ subunit is also present in the skeletal muscle channel complex.
There are ten mammalian VGCC α
1
subunits: four Ca
V
1 channels are termed L‐type, three Ca
V
2 channels are termed P/Q, N, and R; and three Ca
V
3 channels are termed T‐type.
The α
2
δ and β auxiliary subunits increase channel trafficking and affect Ca
V
1 and Ca
V
2 channel properties.
The Ca
V
3 T‐type channels do not associate with auxiliary subunits.
Inhibitory modulation of Ca
V
2 channels by G‐protein coupled receptors is mediated by Gβγ subunits which act in a voltage‐dependent manner.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
