Deletion of the Sequence Encoding the Tail Domain of the Bone Morphogenetic Protein type 2 Receptor Reveals a Bone Morphogenetic Protein 7-Specific Gain of Function

The bone morphogenetic protein (BMP) type II receptor (BMPR2) has a long cytoplasmic tail domain whose function is incompletely elucidated. Mutations in the tail domain of BMPR2 are found in familial cases of pulmonary arterial hypertension. To investigate the role of the tail domain of BMPR2 in BMP signaling, we generated a mouse carrying a Bmpr2 allele encoding a non-sense mediated decay-resistant mutant receptor lacking the tail domain of Bmpr2. We found that homozygous mutant mice died during gastrulation, whereas heterozygous mice grew normally without developing pulmonary arterial hypertension. Using pulmonary artery smooth muscle cells (PaSMC) from heterozygous mice, we determined that the mutant receptor was expressed and retained its ability to transduce BMP signaling. Heterozygous PaSMCs exhibited a BMP7‑specific gain of function, which was transduced via the mutant receptor. Using siRNA knockdown and cells from conditional knockout mice to selectively deplete BMP receptors, we observed that the tail domain of Bmpr2 inhibits Alk2‑mediated BMP7 signaling. These findings suggest that the tail domain of Bmpr2 is essential for normal embryogenesis and inhibits Alk2‑mediated BMP7 signaling in PaSMCs

Remote Patient Monitoring for Patients with Heart Failure: Sex- and Race-based Disparities and Opportunities

Remote patient monitoring (RPM), within the larger context of telehealth expansion, has been established as an effective and safe means of care for patients with heart failure (HF) during the recent pandemic. Of the demographic groups, female patients and black patients are under-enrolled relative to disease distribution in clinical trials and are under-referred for RPM, including remote haemodynamic monitoring, cardiac implantable electronic devices (CIEDs), wearables and telehealth interventions. The sex- and race-based disparities are multifactorial: stringent clinical trial inclusion criteria, distrust of the medical establishment, poor access to healthcare, socioeconomic inequities, and lack of diversity in clinical trial leadership. Notwithstanding addressing the above factors, RPM has the unique potential to reduce disparities through a combination of implicit bias mitigation and earlier detection and intervention for HF disease progression in disadvantaged groups. This review describes the uptake of remote haemodynamic monitoring, CIEDs and telehealth in female patients and black patients with HF, and discusses aetiologies that may contribute to inequities and strategies to promote health equity

Bmpr2 expression in PaSMCs obtained from WT or <i>Bmpr2</i>^{<i>Δtd/+</i>} mice.

<p>(A) Levels of <i>Bmpr2</i> mRNA were measured in WT (Bmpr2^+/+) or <i>Bmpr2</i>^{<i>Δtd/+</i>} PaSMCs by qPCR using hydrolysis probes for <i>Bmpr2</i> exon junctions 6–7 and 12–13. <i>Bmpr2</i> mRNA levels were normalized to <i>Gapdh</i> and expressed as the fold-change relative to <i>Bmpr2</i>^<i>+/+</i> PaSMCs. *P < 0.01 compared to <i>Bmpr2</i>^<i>+/+</i> PaSMCs. (B) Immunoblots prepared from lysates of <i>Bmpr2</i>^<i>+/+</i> and <i>Bmpr2</i>^{<i>Δtd/+</i>} PaSMCs were incubated with an antibody directed against the tail domain of Bmpr2 to detect Bmpr2‑WT or with an anti-GFP antibody to detect Bmpr2‑ΔTD. Immunoblots were subsequently incubated with an antibody directed against Gapdh as a control for protein loading. (C) Confocal microscopy image of a PaSMC transiently transfected with a plasmid directing expression of <i>Bmpr2</i>^<i>Δtd</i> and reacted with an anti-GFP antibody showing localization of Bmpr2‑ΔTD at the cell membrane.</p

Bmpr2‑ΔTD contributes to BMP7 signaling in <i>Bmpr2</i>^{<i>Δtd/+</i>} PaSMCs.

<p>(A) <i>Bmpr2</i>^{<i>Δtd/+</i>} PaSMCs were transfected with negative control siRNA (siNC), si<i>Bmpr2</i>‑ex12, or si<i>Egfp</i> (30 nM). After 48 h, the ability of BMP7 (10 ng/ml for 1.5 h) to induce <i>Id1</i> and <i>Smad6</i> mRNA expression was measured by qPCR, normalized to <i>Gapdh</i> and expressed as fold-change relative to <i>Bmpr2</i>^{<i>Δtd/+</i>} PaSMCs transfected with siNC. *P < 0.01 compared to siNC group treated with BMP7, ^† P<0.01 compared to si<i>Bmpr2</i>‑ex12 group treated with BMP7. Efficiency of silencing <i>Bmpr2</i>^<i>+</i> (si<i>Bmpr2</i>‑ex12) and <i>Bmpr2</i>^<i>Δtd</i> (si<i>Egfp</i>) transcripts was measured by qPCR. (B) <i>Bmpr2</i>^{<i>Δtd/flox</i>} and <i>Bmpr2</i>^{<i>Δtd/del</i>} PaSMCs were treated with BMP4 or BMP7 (10 ng/ml) for 30 and 60 minutes, upon which the activation of Smad1/5/8 was evaluated by immunoblotting. Quantification of the Smad1/5/8 activation is plotted as the ratio of pSmad1/5/8 to total Smad1/5/8. (C) The ability of BMP4 or BMP7 to induce <i>Id1</i> and <i>Smad6</i> gene expression in <i>Bmpr2</i>^{<i>Δtd/flox</i>} and <i>Bmpr2</i>^{<i>Δtd/del</i>} PaSMCs was measured by qPCR, normalized to <i>Gapdh</i> and expressed as fold-change relative to untreated <i>Bmpr2</i>^{<i>Δtd/flox</i>} PaSMCs. *P < 0.01 compared to <i>Bmpr2</i>^{<i>Δtd/flox</i>} PaSMC group treated with BMP7.</p

Bmpr2‑TD attenuates Alk2‑mediated BMP7 signaling in PaSMCs.

<p>Alk3‑deficient <i>Bmpr2</i>^{<i>Δtd/+</i>} PaSMCs were transfected with specific siRNA to silence <i>Bmpr2</i>^<i>+</i> (si<i>Bmpr2</i>‑ex12) or <i>Bmpr2</i>^<i>Δtd</i> (si<i>Egfp</i>) transcripts. After 48 h, the ability of BMP7 to induce <i>Id1</i> and <i>Smad6</i> gene expression was measured by qPCR, normalized to <i>Gapdh</i> and expressed as fold-change relative to <i>Bmpr2</i>^{<i>Δtd/+</i>}; <i>Alk3</i>^{<i>del/del</i>} PaSMCs treated with siNC. *P < 0.01 compared to control cells (siNC) treated with BMP7. Silencing efficiency was quantified by qPCR.</p

BMP7 signaling is enhanced in <i>Bmpr2</i>^{<i>Δtd/+</i>} PaSMCs.

<p>(A) Immunoblots of lysates of WT (Bmpr2^+/+) or <i>Bmpr2</i>^{<i>Δtd/+</i>} PaSMCs treated with BMP4 or BMP7 (10 ng/ml) for various times were reacted with antibodies directed against phosphorylated and total Smad1/5/8. Quantification of the ratio of phosphorylated Smad1/5/8 to total Smad1/5/8 (analysis of 3 independent experiments) demonstrated that BMP4 signaling is similar in <i>Bmpr2</i>^<i>+/+</i> or <i>Bmpr2</i>^{<i>Δtd/+</i>} PaSMCs, whereas BMP7 signaling is greater in <i>Bmpr2</i>^{<i>Δtd/+</i>} PaSMCs. *P<0.05 compared to <i>Bmpr2</i>^<i>+/+</i> PaSMC group treated with BMP7. <i>Id1</i> (B) and <i>Smad6</i> (C) mRNA levels were measured by qPCR in <i>Bmpr2</i>^<i>+/+</i> or <i>Bmpr2</i>^{<i>Δtd/+</i>} PaSMCs treated with BMP4 or BMP7 (10 ng/ml) for various times. <i>Id1</i> and <i>Smad6</i> gene expression was normalized to <i>Gapdh</i> and expressed as fold-change relative to control <i>Bmpr2</i>^<i>+/+</i> PaSMC group. *P < 0.01 compared to <i>Bmpr2</i>^<i>+/+</i> PaSMC group treated with BMP7.</p

BMP7 preferentially utilizes Alk2 in <i>Bmpr2</i>^{<i>Δtd/+</i>} PaSMCs.

<p>(A) The ability of BMP4 or BMP7 (10 ng/ml for 1.5 h) to induce <i>Id1</i> and <i>Smad6</i> gene expression, in <i>Bmpr2</i>^{<i>Δtd/+</i>} PaSMCs deficient in Alk2 or expressing Alk2 was examined by qPCR. <i>Id1</i> and <i>Smad6</i> gene expression was normalized to <i>Gapdh</i> and expressed as fold-change relative to <i>Bmpr2</i>^{<i>Δtd/+</i>}<i>; Alk2</i>^{<i>flox/flox</i>} PaSMCs. *P < 0.01 compared to <i>Bmpr2</i>^{<i>Δtd/+</i>}<i>; Alk2</i>^{<i>flox/flox</i>} PaSMCs treated with BMP7. (B) The ability of BMP4 or BMP7 (10 ng/ml for 1.5 h) to induce <i>Id1</i> and <i>Smad6</i> gene expression, in <i>Bmpr2</i>^{<i>Δtd/+</i>} PaSMCs deficient in Alk3 or expressing Alk3 was measured by qPCR. <i>Id1</i> and <i>Smad6</i> gene expression was normalized to <i>Gapdh</i> and expressed as fold-change relative to <i>Bmpr2</i>^{<i>Δtd/+</i>}<i>; Alk3</i>^{<i>flox/flox</i>} PaSMCs. *P < 0.01 compared to <i>Bmpr2</i>^{<i>Δtd/+</i>}<i>; Alk3</i>^{<i>flox/flox</i>} PaSMC treated with BMP4.</p

BMP7 signaling in <i>Bmpr2</i>^{<i>Δtd/+</i>} and <i>Bmpr2</i>^{<i>Δtd/del</i>} PaSMCs does not depend on the presence of Acvr2a.

<p>(A) <i>Bmpr2</i>^{<i>Δtd/+</i>} PaSMCs were treated with a siRNA specific for <i>Acvr2a</i> transcripts. The ability of BMP4 or BMP7 (10 ng/ml for 1.5 h) to induce <i>Id1</i> and <i>Smad6</i> gene expression was measured by qPCR, normalized to <i>Gapdh</i> and expressed as fold-change relative to <i>Bmpr2</i>^{<i>Δtd/+</i>} PaSMCs treated with siNC. *P < 0.01 compared to siNC within BMP treatment. Silencing efficiency was quantified by measuring <i>Acvr2a</i> mRNA levels. (B) <i>Bmpr2</i>^{<i>Δtd/del</i>} PaSMCs were treated with si<i>Acvr2a</i>. The ability of BMP4 or BMP7 (10 ng/ml for 1.5 h) to induce <i>Id1</i> and <i>Smad6</i> gene expression was measured by qPCR, normalized to <i>Gapdh</i> and expressed as fold-change relative to <i>Bmpr2</i>^{<i>Δtd/del</i>} PaSMCs treated with siNC. *P < 0.01 compared to siNC within BMP treatment. <i>Acvr2a</i> silencing efficiency was measured by qPCR.</p