Enhanced Ca²⁺signaling, mild primary aldosteronism, and hypertension in a familial hyperaldosteronism mouse model (Cacna1h^M1560V/+)

Abstract

Gain-of-function mutations in the CACNA1H gene (encoding the T-type calcium channel CaV3.2) cause autosomal-dominant familial hyperaldosteronism type IV (FH-IV) and early-onset hypertension in humans. We used CRISPR/Cas9 to generate Cacna1hM1560V/+ knockin mice as a model of the most common FH-IV mutation, along with corresponding knockout mice (Cacna1h−/−). Adrenal morphology of both Cacna1hM1560V/+ and Cacna1h−/− mice was normal. Cacna1hM1560V/+ mice had elevated aldosterone:renin ratios (a screening parameter for primary aldosteronism). Their adrenal Cyp11b2 (aldosterone synthase) expression was increased and remained elevated on a high-salt diet (relative autonomy, characteristic of primary aldosteronism), but plasma aldosterone was only elevated in male animals. The systolic blood pressure of Cacna1hM1560V/+ mice was 8 mmHg higher than in wild-type littermates and remained elevated on a high-salt diet. Cacna1h−/− mice had elevated renal Ren1 (renin-1) expression but normal adrenal Cyp11b2 levels, suggesting that in the absence of CaV3.2, stimulation of the renin-angiotensin system activates alternative calcium entry pathways to maintain normal aldosterone production. On a cellular level, Cacna1hM1560V/+ adrenal slices showed increased baseline and peak intracellular calcium concentrations in the zona glomerulosa compared to controls, but the frequency of calcium spikes did not rise. We conclude that FH-IV, on a molecular level, is caused by elevated intracellular Ca2+ concentrations as a signal for aldosterone production in adrenal glomerulosa cells. We demonstrate that a germline Cacna1h gain-of-function mutation is sufficient to cause mild primary aldosteronism, whereas loss of CaV3.2 channel function can be compensated for in a chronic setting.

Genetics of Primary Aldosteronism

“…Adrenals from these animals have elevated baseline and peak intracellular Ca 2+ levels. 89 Last, a transgenic mouse with adrenocortical expression of a Gq-coupled designer receptor develops disorganization of adrenal zonation and hyperaldosteronism, 90 as in GNAQ mutations in APAs. Additional models with mutations in KCNK3 and KCNK9 potassium channels or cryptochrome genes have been reviewed elsewhere.…”

“…Therapeutic use of calcium channel blockers in PA was considered long before the discovery of calcium channel mutations 99 but approved compounds target vascular calcium channels, and their antihypertensive effect is mostly aldosterone-independent. 5 Normal aldosterone values in Cacna1h knockout mice 89,100 and the phenotype of Cacna1d knockout mice (deafness and sinoatrial node dysfunction with bradycardia and arrhythmia) 101 argue against these channels as therapeutic targets.…”

Cav3.2 deletion attenuates nonalcoholic fatty liver disease in mice

“…As a main member of the T-type calcium channel, Cav3.2 channel has been reported to widely present in tissues throughout the body, including heart, brain, liver, lung, kidney and skin [12,29] . Numerous studies suggested that Cav3.2 channel play a crucial part in the development of various diseases, including myocardial infarction [13] , hypertension [14] , obesity [15] and diabetic neuropathy [16] . In addition, Cav3.2 inhibitors mibefradil and NNC 55-0396 were proven to improve hyperglycemia and hyperlipidemia in db/db mice [30] .…”

“…Cav3.2 channel is an important member of T-type calcium channel and involved in many cellular processes with different cell activities by regulating calcium in ux, including proliferation, migration, differentiation and apoptosis [11,12] . Numerous studies suggested that Cav3.2 channel play a crucial part in the development of various diseases, including myocardial infarction [13] , hypertension [14] , obesity [15] and diabetic neuropathy [16] . However, little is known on the function of Cav3.2 channel in the progression of NAFLD.…”

Intrinsic Adrenal TWIK-Related Acid-Sensitive TASK Channel Dysfunction Produces Spontaneous Calcium Oscillations Sufficient to Drive AngII (Angiotensin II)-Unresponsive Hyperaldosteronism

“…In mice, several aldosterone-associated hypertensive models generated by ion channel gain-of-function (GOF, eg, ClC-2 Clchannels [Clcn2 R180Q/+ , Clcn2 op/op ], 19,21 Ca v 3.2 calcium channels [Cacna1h M1560V/+ ] 28 ) or loss-of-function (LOF, eg, TWIK-related acid-sensitive potassium [TASK] channels [Kcnk3, Kcnk9, alone and together] 16,[29][30][31][32] ) replicate many of the defining features of human PA. Collectively, these mouse models indicate that genetically altered cells, including Cyp11b2-positive cells, can produce mild to severe RAS-independent hyperaldosteronism in vivo.…”