Dual Role of CACNA1C/Ca_V1.2 in Cardiac and Neuropsychiatric Disease

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript provides a highly timely, comprehensive, and well-structured review of the dual roles of the L-type calcium channel CaV1.2 (encoded by the CACNA1C gene) across both cardiac and neuropsychiatric pathologies. Integrating molecular biology, behavioral animal models, neuro-immune interactions, cardiac electrophysiology, and clinical therapeutics into a single cohesive narrative is an ambitious and highly valuable contribution to the field.

The flow of the manuscript, progressing from genetic backgrounds to behavioral phenotyping, cellular mechanisms, cardiac pathophysiology, and finally clinical outlooks, is logically rigorous. However, to elevate the manuscript to a level suitable for publication in a high-impact journal, several critical areas require refinement. Specifically, the authors need to address inconsistencies in academic terminology, integrate recent paradigm shifts in channel regulation (e.g., Rad-mediated regulation), clarify the preserved current paradox, and expand on underrepresented Timothy Syndrome (TS) mutant forms (G402S and G419R).

1. The authors do an excellent job describing the historic paradigm shift in β-adrenergic-mediated upregulation of Ca_V1.2 current, transitioning from the classical α1C direct phosphorylation model (e.g., Ser-1700) to the modern Rad-GEM GTPase-mediated disinhibition model. However, the current text presents the relationship and ongoing debates between these two models in a somewhat ambiguous manner. Please revise this section to clearly delineate that PKA-mediated phosphorylation of Rad (which relieves its constitutive inhibition on Ca_V1.2) is now widely accepted as the primary driver of β-adrenergic stimulation. Concurrently, clarify that direct phosphorylation of the α1C subunit may still play a secondary, modulatory, or localized role, thereby providing a more balanced and precise overview of the current academic consensus.
2. The manuscript discusses the intriguing paradox where heterozygous knockout mice (Cacna1c^+/−) maintain normal basal L-type calcium currents in cardiomyocytes despite a 50% reduction in gene dosage. While the authors propose three plausible hypotheses (post-translational modifications, membrane-bound channel preservation, and localized PKA hyperactivation), the causal link between this basal compensation and the subsequent failure under stress is not fully articulated. To strengthen the logical flow, please explicitly state that because these cardiomyocytes pre-emptively exhaust their localized PKA signaling (e.g., baseline elevation of Ser-1928 phosphorylation) to maintain normal basal currents, they suffer from a depleted Sympathetic Reserve. Consequently, when subjected to acute physiological stress or β-adrenergic challenge, the system fails to recruit additional calcium currents, leading to contractile dysfunction. Adding a summarizing sentence to encapsulate this exhausted reserve concept will greatly benefit the reader.
3. The authors cite pioneering work (e.g., Cahalan 2022) demonstrating that in certain immune cells (like T-cells), Ca_V1.2 may not function as a classical voltage-gated ion channel, but rather operates via protein-protein interactions or non-conducting mechanisms. However, this non-canonical role is juxtaposed against the classical conducting roles in microglia and astrocytes without sufficient distinction, which may confuse readers. I recommend to clearly differentiate between excitable cells (neurons, cardiomyocytes) and non-excitable immune cells. Please introduce a dedicated subsection or a clarifying schematic/table highlighting that in non-excitable immune cells, Ca_V1.2 frequently acts as a scaffolding protein or a signaling hub rather than a simple ion conductor. This distinction will significantly enhance the mechanistic depth of the neuroinflammation section.
4. While the manuscript extensively discusses the classic Timothy Syndrome (TS1) mutation (G406R in exon 8a) and its impact on voltage-dependent inactivation (VDI), it completely omits other critical pathogenic mutant forms of CACNA1C, specifically G402S (associated with atypical TS2) and G419R. Discussing these mutations is essential for a truly comprehensive review of Ca_V1.2 pathophysiology.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The paper "Dual Role of CACNA1C/CaV1.2 in Cardiac and Neuropsychiatric Disease" by Königstein et al. is an excellent review that provides a detailed analysis of the relationship between CaV1.2 channels and cardiac and neuropsychiatric diseases.

The manuscript is well-written and organized; it includes four highly illustrative figures and an extensive, up-to-date list of references.

I have only a few minor observations for the authors:

1. The abbreviation LTCC is used multiple times starting at line 315 but is not defined until line 601.
2. Regarding section 3.6 (starting at line 411), it might be useful to include a brief note explaining how voltage-gated CaV1.2 calcium channels are activated in non-excitable cells (such as microglia and lymphocytes), given that action potentials are not generated in these cells.
3. In Figure 1, the illustration of the CaV1.2 channel domain structure could be improved by reflecting the relative lengths of the three intracellular loops: the II-III loop is the longest, followed by the I-II loop, with the III-IV loop being the shortest.
4. Figure 3 could be improved by ensuring the representation of the CaV1.2 channel reflects that the alpha-2 subunit is significantly larger than the delta subunit and that the alpha-2 subunit interacts with the alpha-1 subunit.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript is valuable as an integrative review of the CACNA1C–Cav1.2–brain–heart axis. Its contribution lies not in proposing novel mechanisms, but in bringing together genetic evidence, experimental models, excitation–transcription coupling, plasticity, memory, immunity, glial function, cardiac compensation, and potential therapeutic applications within a single framework. This synthesis may benefit researchers from diverse fields and help define a more precise experimental agenda. The text stands out for its breadth and relevance, but requires greater documentary rigor, stronger reliance on primary references, and a clearer classification of the available evidence.

General comment:
The authors could strengthen the review by prioritizing the following tasks: ranking the evidence, moderating categorical claims, updating the sections on Brugada syndrome and pharmacotherapy, and providing greater detail on the experimental models.
Specific comments:
1. The discussion of Brugada syndrome requires updating. Recent studies have re‑evaluated the proposed link between CACNA1C and Brugada, while the association with Timothy syndrome/LQT8 continues to represent the most firmly established clinical relationship.
2. The neuropsychiatric section should be organized around four main topics: human genetic associations; functional effects of common and rare variants; animal models; and implications for neural circuits and behavior.
3. The authors should also avoid grouping schizophrenia, bipolar disorder, depression, ADHD, and autism as though they were equivalent manifestations of a single CaV1.2 abnormality.
4. Similarly, well-established pathogenic variants should not be placed in the same category as common risk SNPs.
5. With regard to pharmacology, the authors should distinguish CCBs by class, as the term “CCBs” is overly broad. For example, they could use dihydropyridines, such as amlodipine, nifedipine, and nimodipine; phenylalkylamines, such as verapamil; and benzothiazepines, such as diltiazem.
6. The conclusion should state that currently available drugs are not selective CACNA1C inhibitors acting on a specific brain circuit. In addition, negative results from observational studies or verapamil trials do not rule out the possibility of developing more selective molecular therapies, but they do argue against presenting CCBs as general psychiatric treatments. Such wording avoids conveying the impression that their psychiatric utility has been conclusively demonstrated.
7. When possible, animal models should be detailed, with species, sex, age, genetic background, and mutation type specified, .
8. It may be helpful to present the discussions on mitochondria, glia, and immunity with greater caution. These topics can remain, but should be positioned as developing fields rather than definitive mechanisms.
9. The concluding section should incorporate a dedicated limitations subsection, explicitly addressing interspecies variability, distinctions between global and cell‑specific models, the restricted predictive value of behavioral assays, the modest effects of common variants, indication bias in studies of calcium channel blockers, and the unresolved roles of glia, mitochondria, and immunity.
10. The reference list would benefit from being updated, replacing older citations with more recent studies where possible. It should also include current reviews on Timothy syndrome and CACNA1C‑related disorders, and the section on calcium channel blockers and neuropsychiatric outcomes should be revised accordingly. For mechanistic claims, primary research articles should be emphasized rather than depending on broad reviews.

 

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

All suggestions made by this reviewer have been satisfactorily addressed by the authors.