The adult heart requires baseline expression of the transcription factor Hand2 to withstand right ventricular pressure overload

Abstract

Aims Research on the pathophysiology of right ventricular (RV) failure has, in spite of the associated high mortality and morbidity, lagged behind compared to the left ventricle (LV). Previous work from our lab revealed that the embryonic basic helix-loop-helix transcription factor heart and neural crest derivatives expressed-2 (Hand2) is re-expressed in the adult heart and activates a ‘fetal gene program’ contributing to pathological cardiac remodeling under conditions of LV pressure overload. As such, ablation of cardiac expression of Hand2 conferred protection to cardiac stress and abrogated the maladaptive effects that were observed upon increased expression levels. In this study, we aimed to understand the contribution of Hand2 to RV remodeling in response to pressure overload induced by pulmonary artery banding (PAB). Methods and Results In the present study, Hand2F/F and MCM- Hand2F/F mice were treated with tamoxifen (control and knockout, respectively) and subjected to six weeks of RV pressure overload induced by PAB. Echocardiographic- and MRI-derived hemodynamic parameters as well as molecular remodeling were assessed for all experimental groups and compared to sham-operated controls. Six weeks after PAB, levels of Hand2 expression increased in the control banded animals but, as expected, remained absent in the knockout hearts. Despite the dramatic differences in Hand2 expression, pressure overload resulted in impaired cardiac function independently of the genotype. In fact, Hand2 depletion seems to sensitize the RV to pressure overload as these mice develop more hypertrophy and more severe cardiac dysfunction. Higher expression levels of HAND2 were also observed in RV samples of human hearts from patients with pulmonary hypertension. In turn, the LV of RV-pressure overloaded hearts was also dramatically affected as reflected by changes in shape, decreased LV mass and impaired cardiac function. RNA sequencing revealed a distinct set of genes that are dysregulated in the pressure-overloaded RV, compared to the previously described pressure-overloaded LV. Conclusions Cardiac-specific depletion of Hand2 is associated with severe cardiac dysfunction in conditions of RV pressure overload. While inhibiting Hand2 expression can prevent cardiac dysfunction in conditions of LV pressure overload, the same does not hold true for conditions of RV pressure overload. This study highlights the need to better understand the molecular mechanisms driving pathological remodeling of the RV in contrast to the LV, in order to better diagnose and treat patients with RV or LV failure. Translational Perspective RV failure associated with pulmonary hypertension reduces long-term survival rate to 55% within 3 years, suggesting that 3 years after diagnosis almost half of the patients will die. To revert these numbers an adequate RV-specific and, therefore, more efficient treatment is needed. Our work suggests that current therapies and potential mechanisms underlying LV failure may not be suitable for RV failure. While Hand2 deletion is favorable in LV response to stress, it is particularly detrimental in the RV under similar conditions, and thus, highlighting potential severe consequences of not differentiating therapeutic targets or treatment for RV or LV failure.

Distinct HAND2/HAND2-AS1 Expression Levels Finetune Mesenchymal and Epithelial Cell Plasticity in Human Mesenchymal Stem Cells

“…There it is induced by upstream progesterone (P4)-Indian hedgehog (IHH) signaling during menstrual cycles and initiates downstream MET (also termed decidualization 59 )-a key requirement for blastocyst receptivity during implantation 60 . In wider adult-tissue pathological contexts (type 2/3 MET), however, HAND2 is associated with endometriosis induction (upregulating proinflammatory IL15 expression 61,62 ), right ventricle protection from pressure overload damage 26 , familial dilated cardiomyopathy 63 , onset of mesothelioma malignancies 30 and obesity (regulated by glucocorticoid signaling) 64 . HAND2 is also silenced in colorectal cancer (via hypermethylation correlated with poor prognosis) and has been identified as an epigenetic driver gene and a potential tumor suppressor (via MAPK/ERK signaling) 65 .…”

“…One possible downstream common mediator of MET may be heart and neural crest derivatives 2 (HAND2), a type B basic helix-loop-helix (bHLH) transcription factor (TF) 24 , and its associated anti sense long non-coding RNA (lncRNA, HAND2-AS1). Embryonically, HAND2 induces type 1 (embryonic) MET patterning of NCCs to branching aortic vessels and of mesodermal second heart field (SHF) cells to the right ventricle (RV), parts of the atria, interventricular septum, and outflow tract [25][26][27] . HAND2 murine knockout (KO) is lethal at E9.5-10.5, yielding RV hypoplasia, single chambered hearts, and vascular malformations 25,28 .…”

Distinct HAND2/HAND2-AS1 Expression Levels May Fine-Tune Mesenchymal and Epithelial Cell Plasticity of Human Mesenchymal Stem Cells

“…At this level, it is induced by upstream progesterone (P4)-Indian hedgehog (IHH) signaling during menstrual cycles and initiates a downstream MET (also termed decidualization [57])-a key requirement for blastocyst receptivity during implantation [58]. In wider adult tissue pathological contexts (type 2/3 MET), however, HAND2 is associated with endometriosis induction (upregulating proinflammatory IL15 expression [59,60]), right ventricle protection from pressure overload damage [26], familial dilated cardiomyopathy [61], the onset of mesothelioma malignancies [30], and obesity (regulated by glucocorticoid signaling) [62]. HAND2 is also silenced in colorectal cancer (via hypermethylation correlated with poor prognosis) and has been identified as an epigenetic driver gene and a potential tumor suppressor (via MAPK/ERK signaling) [63].…”

“…One possible downstream common mediator of MET may be heart and neural crest derivatives 2 (HAND2), a type B basic helix-loop-helix (bHLH) transcription factor (TF) [24], and its associated antisense long non-coding RNA (lncRNA; HAND2-AS1). Embryonically, HAND2 induces type 1 (embryonic) MET patterning of NCCs to branching aortic vessels and of mesodermal second heart field (SHF) cells to the right ventricle (RV), parts of the atria, interventricular septum, and outflow tract [25][26][27]. HAND2 murine knockout (KO) is lethal at ED9.5-10.5, yielding RV hypoplasia, single-chambered hearts, and vascular malformations [25,28].…”

Transcription Factor Regulation of Gene Expression Network by ZNF385D and HAND2 in Carotid Atherosclerosis

“…Its regulatory targets have been found to control mesenchymal transition underlying cardiac cushion development in the atrioventricular canal [12]. A recent study found that a baseline expression of the gene in the adult heart is required to withstand right ventricular pressure overload [13]. Variation of the ZNF385D gene (rs13070110) was nominally associated with an increased risk of intracerebral hemorrhage [14].…”