Objective: The calmodulin-binding transcription activator 2 (CAMTA2) promotes transcription of genes involved in cardiac hypertrophy through its interaction with Nkx2.5 and is an indispensable transcription coactivator for cardiac hypertrophy. We hypothesized that variants in the coding region of CAMTA2 would affect its function and confer a risk of cardiac hypertrophy.
Methods: The effects of the variant rs238234 on the activity of the atrial natriuretic factor promoter and on the cardiomyocytes hypertrophy were assessed in the H9C2 cell line and primary neonatal rat cardiomyocytes, respectively. Furthermore, the association of this variant with left ventricular hypertrophy (LVH) was tested in hypertensive patients with and without hypertrophy (N = 325 and 697), and this analysis was replicated in an independent population of 987 hypertensive patients without hypertrophy and 463 hypertensive patients with hypertrophy.
Results: We found that the G allele of rs238234 activated the atrial natriuretic factor promoter more strongly than the C allele. The cell size of cardiomyocytes was larger in the presence of the Ad-CAMTA2 G allele, and the G allele was associated with significantly increased susceptibility to LVH in hypertensive [odds ratio (OR), 1.29; P = 0.009]. In the discovery cohort, after adjusting for age and sex, the GG genotype was significantly associated with increased LVH risk (OR, 1.75; P = 0.015). There was little attenuation of the ORs (1.62; P < 0.05) when adjusting for BMI, heart rate, blood pressure, smoking, and drinking and further adjusting all covariates including lipid levels and other major risk factors. However, the GC genotype did not show any association with LVH using three regressive models. Replication in the second study yielded similar results.
Conclusion: Our results provide evidence that the rs238234 GG genotype in the coding region of CAMTA2 may increase the risk of LVH by affecting the activation of Nkx2.5-dependent transcription.