Cardiac-specific inactivation of Prdm16 effects cardiac conduction abnormalities and cardiomyopathy-associated phenotypes

Abstract

A variant in the PRDM16 locus has been correlated with QRS duration in an electrocardiogram genome-wide association study, and the deletion of PRDM16 has been implicated as a causal factor of the dilated cardiomyopathy that is linked to 1p36 deletion syndrome. We aimed to determine how a null mutation of Prdm16 affects cardiac function and study the underlying mechanism of the resulting phenotype in an appropriate mouse model. We used cardiac-specific Prdm16 conditional knockout mice to examine cardiac function by electrocardiography. QRS duration and QTc interval increased significantly in cardiac-specific Prdm16 knockout animals compared with wild-type mice. Further, we assessed cardiomyopathy-associated features by trichrome staining, densitometry, and hydroxyproline assay. Prdm16-null hearts showed greater fibrosis and cardiomyocyte hypertrophy. By quantitative real-time PCR, Prdm16-null hearts upregulated extracellular matrix-related genes ( Ctgf, Timp1) and α-smooth muscle actin ( Acta2), a myofibroblast marker. Moreover, TGF-β signaling was activated in Prdm16-null hearts, as evidenced by increased Tgfb1–3 transcript levels and phosphorylated Smad2. However, the inhibition of TGF-β receptor did not reverse the aberrations in conduction in cardiac-specific Prdm16 knockout mice. To determine the underlying mechanisms, we performed RNA-seq using mouse left ventricular tissue. By functional analysis, Prdm16-null hearts experienced dysregulated expression of ion channel genes, including Kcne1, Scn5a, Cacna1h, and Cacna2d2. Mice with Prdm16-null hearts develop abnormalities in cardiac conduction and cardiomyopathy-associated phenotypes, including fibrosis and cellular hypertrophy. Further, the RNA-seq findings suggest that impairments in ion homeostasis (Ca2+, K+, and Na+) may at least partially underlie the abnormal conduction in cardiac-specific Prdm16 knockout mice. NEW & NOTEWORTHY This is the first study that describes aberrant cardiac function and cardiomyopathy-associated phenotypes in an appropriate murine genetic model with cardiomyocyte-specific Prdm16-null mutation. It is noteworthy that the correlation of PRDM16 with QRS duration is replicated in a murine animal model and the potential underlying mechanism may be the impairment of ion homeostasis.

Prdm16 amplifies Notch signaling and suppresses venous lineage specification to prevent arteriovenous malformations during vascular development

“…In line with its described role during cardiac development, 34,36 we observed severe cardiac defects in prdm16 morphants, precluding the visualization and reliable quantification of aortic anomalies. We therefore generated Tg(cmlc2:PRDM16) zebrafish which overexpress human fulllength PRDM16 in their cardiomyocytes.…”

“…By detailed analysis of Prdm16's expression pattern across species, we provide evidence that Prdm16 co-defines arteriovenous identity of ECs in mammals and zebrafish across the vascular system, irrespective of developmental stage, anatomical location and hemodynamic factors. Studies in zebrafish embryos further revealed that the cardiovascular role of prdm16 extends beyond the heart muscle, 34,36 as prdm16 deficiency resulted in cell-autonomous arterial defects.…”

“…Of note, the severe cardiac defects in prdm16 morphants, in line with Prdm16's described role during cardiac development, 30,33 precluded the visualization and reliable quantification of aortic anomalies due to the absence of flow. To assess the vascular effect of prdm16-deficiency independent of hemodynamics, we generated Tg(cmlc2:PRDM16) zebrafish which overexpress human full-length PRDM16 in their cardiomyocytes.…”

Defective brown adipose tissue thermogenesis and impaired glucose metabolism in mice lacking Letmd1

“…BAT is the primary site of expression for Letmd1 (Figures 1B and S1A). In contrast, Prdm16 and Ebf2 exhibit more widespread tissue expression and regulate the development of vital tissues such as the brain, hematopoietic cells, and the cardiac conduction system (Aguilo et al, 2011;Bjork et al, 2010;Chuang et al, 2011;Kieslinger et al, 2010;Nam et al, 2020), which may explain why Prdm16 KO and Ebf2 KO are embryonic lethal. The Letmd1 KO mice are viable and grow normally (Figure 2B), and yet its BAT phenotype is more severe, resulting in defective BAT formation (Figures 3A, 3F, and 3K), impaired acute and chronic cold adaptation (Figures 2C and 4C), and increased susceptibility to diet-induced obesity (Figures 2H and 2I).…”

New variant of PRDM16 gene nucleotide sequence in a family with various phenotypic manifestations of the non-compacted myocardium

“…Последующие исследования подтвердили роль вариантов, приводящих к утрате копии PRDM16, в развитии НМЛЖ и дилатационной КМП у детей [18]. В экспериментах на нокаутированных по гену PRDM16 мышах была показана роль PRDM16 в развитии гипертрофической КМП [17,19] [16], однако для однозначного вывода о связи этого гена с НМЛЖ и первичными КМП имеющихся данных недостаточно.…”