Biology subjects

Hare, J. M.

Publications and source records attributed to Hare, J. M..

15 recordsLinked to original sources

bioRxiv2026

LMNA Haploinsufficiency in Human iPSC-Derived Cardiac Organoids Reveals Early Fibrotic Signaling as a Therapeutically Targetable Process

LMNA mutations are a major cause of dilated cardiomyopathy (DCM), with haploinsufficiency representing a common pathogenic mechanism. Yet the earliest disease-initiating events remain poorly defined. Here, we identify a novel intronic splice-site variant, c.937-1G>A, that disrupts pre-mRNA processing and induces nonsense-mediated mRNA decay, resulting in LMNA haploinsufficiency. Using induced pluripotent stem cells (iPSCs) generated from the patients peripheral blood mononuclear cells (PBMCs), we differentiated into self-patterning human cardiac organoids to model early LMNA-DCM in a multicellular human context. Single-nucleus transcriptomics revealed unexpectedly broad remodeling across major cardiac cell types beyond cardiomyocytes. Functionally, LMNA-mutant organoids exhibited impaired contractility, altered calcium handling, and increased arrhythmic activity. These changes were accompanied by early profibrotic activation, including increased reactive oxygen species (ROS), periostin (POSTN) secretion, and CTGF expression. Treatment with the antifibrotic drug nintedanib attenuated this response. Together, these findings show that LMNA haploinsufficiency initiates global pathogenic remodeling at an unexpectedly early developmental stage.

cell biology↗

bioRxiv2026

Archaic translation initiation factor eIF5B supports KSHV late lytic replication and viral oncogenesis by mimicking a hypoxic cellular landscape

Kaposis Sarcoma (KS) Herpesvirus (KSHV) is the etiological agent of KS, an AIDS-defining illness. Recent studies have demonstrated that even during normoxic conditions, KSHV facilitates replication by modulating hypoxia-inducible factors (HIFs), creating a hypoxia-like environment that promotes cellular transformation. KSHV lytic viral genes are favored for protein synthesis during infection by upregulating HIF2 and utilizing the hypoxic eIF4E2 translation initiation complex in oxygen-replete conditions. This translation initiation plasticity (TRIP) links viral replication strategies to angiogenic signaling and oncogenicity. However, the molecular basis of this plasticity remains poorly understood. This study reveals that viral inhibition of eukaryotic initiation factor 2 (eIF2) induces the use of another alternative initiation factor, eIF5B, which canonically mediates delivery of initiator methionine-tRNAiMet during hypoxia. We demonstrate through ribosome density fractionation that eIF2 accumulates in translationally inactive monosome fractions while eIF5B redistributes its translation activity toward polysomes during lytic replication. Progressive dependence on eIF5B during KSHV infection was illustrated by impaired late lytic gene expression, diminished virion production, and altered polysome profiles following eIF5B knockdown. Transcriptomic analyses further reveal that the mRNA landscape in KSHV-infected cells depleted of eIF5B mirrors that of uninfected hypoxic cells. Moreover, silencing of eIF5B in a natural infection model reduces both VEGF secretion and anchorage-independent growth--two hallmarks of KSHV viral oncogenicity. These results demonstrate that eIF5B functions as an essential component of alternative translation initiation machinery activated in response to eIF2 inactivation during KSHV lytic replication, emphasizing its key role in viral pathogenesis and its potential as a novel therapeutic target. IMPORTANCEKaposis Sarcoma Herpesvirus (KSHV) is a human cancer virus that causes severe malignancies in immunocompromised individuals, including the blood vessel cancer Kaposis Sarcoma and a highly aggressive body-cavity lymphoma. Although cells mount a response to infection by shutting down global protein synthesis, how viruses like KSHV continue making viral proteins when this cellular machinery is shutdown remains unclear. This study uncovers that KSHV exploits an ancient cellular factor typically used for protein production under low-oxygen conditions. We identify a previously unrecognized role for the translation factor, eIF5B, in supporting KSHV replication and select production of viral proteins during infection. Our work further demonstrates that KSHVs utilization of eIF5B contributes to a hypoxia-like environment during infection, ultimately contributing to cancer-promoting changes within the cell. These findings highlight a new strategy for tumor-virus reprogramming of host cells, opening an avenue for novel therapeutic targets to eliminate virus-associated cancers.

microbiology↗

bioRxiv2025

Rapamycin enhances VEGFA and VSMC contractile protein expression in MSCs via mTORC1 inhibition

IntroductionIntracranial aneurysm (ICA) rupture is the most common cause of non-traumatic subarachnoid hemorrhage, a devastating type of stroke. Vascular smooth muscle (VSMC) and endothelial cell (EC) dysfunction and death play important roles in the etiology of ICA formation, rupture and treatment failure. Mesenchymal stem cells (MSCs) have been extensively investigated for their therapeutic potential in vascular diseases. The mammalian target of rapamycin (mTOR) is a key regulatory pathway involved in cellular functions controlling intracellular anabolic and regulatory processes. Rapamycin, a specific mTOR complex 1 inhibitor, is widely used in the clinical management of cardiac and vascular pathologies. In this study, we explored MSCs potential to express VSMC and EC markers under the influence of rapamycin. MethodsHuman MSCs were treated with rapamycin for 2, 5, and 10 days, and cell death and proliferation determined by MTT analysis. Protein expression and phosphorylation levels were determined by western blot analysis. Calcein AM and PI staining was used to determine cell viability, and morphology. ResultsMTT and Calcein AM analysis demonstrated that prolonged rapamycin treatment did not affect MSC viability but was found to reduce MSC proliferation and cause a nearly threefold increase in cell size compared to controls. Rapamycin treatment increased expression of the VSMC protein markers, -SMA, and transgelin and was required to maintain elevated expression levels both proteins. In contrast, selective inhibition of mTORC2 with JR-AB2-01 caused a decrease in -SMA and trangelin expression, suggesting mTORC1 regulation of -SMA and transgelin expression, rather than mTORC2. Rapamycin treated MSC were also found to induce cell sprouting between adjacent cells. MSCs were found not to express endothelial protein markers under either basal conditions or following rapamycin treatment. However, rapamycin treatment was found to increase VEGFA expression, a known promoter of angiogenesis. ConclusionRapamycin has the potential to increase VSMC protein expression in MSCs by its action on mTORC1. The ability of rapamycin to increase VEGFA expression in MSCs could allow for a novel MSC-based therapeutic intervention in cerebral aneurysm management which could aid in ICA healing and reducing rupture risk.

neuroscience↗

bioRxiv2025

Cardiomyocyte-specific expression of HIF-1α mediates the cardioprotective effects of Growth Hormone-Releasing Hormone (GHRH)

Heart failure (HF) with preserved ejection fraction (HFpEF) carries a high mortality and remains a major therapeutic challenge. Effective, targeted therapies capable of reversing HFpEF pathophysiology are urgently needed. We previously demonstrated that activation of the cardiac growth hormone-releasing hormone (GHRH) pathway using high potency synthetic agonists of GHRH (GHRH-agonists: MR-356 and MR-409) improves the HFpEF phenotype in both large and small animal models, including in a murine model of cardiometabolic HFpEF (High fat diet + the nitric oxide synthase inhibitor L-NAME [HFD+L-NAME]). Here we sought to define the downstream signaling pathways responsible for this effect. A transcriptomic screen in human iPSC-derived cardiomyocytes (hiPSC-CMs) identified the hypoxia-inducible factor (HIF)-1 pathway as being activated by GHRH receptor (GHRHR) signaling, revealing an oxygen-independent mechanism of HIF-1 activation. Based on this finding, we investigated the interaction between the cardioprotective effects of the GHRH-agonist MR-356 and HIF-1 pathway activation in the murine HFD+L-NAME model of cardiometabolic HFpEF. We generated a cardiomyocyte-specific HIF-1 knockout (HIF-1CMKO) mouse line and demonstrated that our previously reported beneficial effects of GHRH-agonist administration were completely abolished in HIF-1CMKO mice. Together, these findings establish the GHRHR-HIF-1 axis as a central pathway integrating metabolic and contractile remodeling, suggesting that therapeutic targeting of this axis represents a novel disease-modifying approach to treating cardiometabolic HFpEF.

physiology↗

bioRxiv2025

Coil and flow diverting stents as drug delivery platforms for cerebral aneurysm treatment

Cerebral aneurysm occlusion with coils and flow diverting stents has become the first line treatment for both unruptured and ruptured cerebral aneurysms. As these technologies have advanced, there have been changes in device shape and surface coating to enhance aneurysm embolization while reducing stent thrombogenicity. Drug eluting stents have been used with great success in the targeted delivery of rapamycin, a mTOR complex 1 inhibitor to prevent restenosis in coronary and peripheral artery disease. However, few studies have investigated the use of coils and stents as delivery platforms for sustained drug release to cerebral aneurysm tissue. In this study, we used the bio-compatible and degradable polymers, gelatin and PLGA and a simple evaporative coating technique to investigate the release of rapamycin over time from coated platinum coils and Pipeline flow diverting stents. Rapamycin coated coils were incubated with human vascular endothelial cells in vitro to confirm therapeutic levels of rapamycin release. The rate of rapamycin release was similar in both gelatin and PLGA coated coils and was sustained for more than three weeks. Rapamycin was bioactive, at a therapeutic dose and inhibited mTOR complex 1 in human brain endothelial cells treated with a rapamycin coated coil. The relative degree of mTOR complex 1 inhibition was greater in PLGA compared to gelatin coated coils. Coating flow diverting stents with a rapamycin-PLGA coating demonstrated continuous rapamycin release over a 35 day period. Reducing the percent PLGA polymer concentration caused a robust and sustainable release of rapamycin. The PLGA coating was resilient enough to allow device recapturing without affecting rapamycin eluting rates or device deployment and expansion. This work provides a simple, feasible and tunable method to coat occlusion devices for preclinical studies investigating targeted drug delivery for improved parent vessel healing and aneurysm obliteration.

bioengineering↗

bioRxiv2025

Cerebral vascular tortuosity and aneurysm formation and rupture: a novel vessel tortuosity scale

Cerebral aneurysm (CA) rupture is the most common cause of nontraumatic subarachnoid hemorrhage. Recent data suggests that tortuosity is associated with aneurysm formation and rupture risk. We aimed to determine if tortuosity correlates with CA development and rupture in a mouse CA model and to develop a novel tortuosity scale to be used for in vivo CA studies. A highly validated, elastase-mouse CA model was used to assess cerebral vessel tortuosity with CA formation and rupture in sham and elastase groups. A 4-point ordinal scale was created to evaluate predictive capacity for vessel tortuosity level and CA formation and rupture. Nearly all sham animals (92%) had little to no vessel tortuosity on the visual scale (median, IQR: 1, [1-2]), compared to 24% in the elastase groups (2, [2-3]) (p=0.001). Sham cohorts had zero animals with highly tortuous vessels, while 3.5mU and 35mU cohorts had >35% of animals with significant visual tortuosity, p=0.003 and p<0.000, respectively. CA formation and rupture was higher in the elastase groups compared to the sham group (p=0.002). Both the visual scale and tortuosity index significantly predicted CA formation (p<0.001) and rupture (p<0.001). A novel tortuosity scale is highly predictive of CA formation and rupture in vivo. It may offer a new measurement to better understand vessel stress in the pathogenesis and progression of CAs.

neuroscience↗

bioRxiv2024

Targeting Endoplasmic Reticulum Stress and Nitroso-Redox Imbalance in Neuroendocrine Prostate Cancer: The Therapeutic Role of Nitric Oxide

Neuroendocrine prostate cancer (NEPC) is an aggressive and therapy-resistant subtype of prostate cancer. Current standard-of-care treatment for NEPC involves chemotherapies, which largely exert their cytotoxic effects by forming DNA crosslinks, disrupting DNA replication and transcription in NEPC cells. However, these therapies are often met with resistance, partly due to increased endoplasmic reticulum (ER) stress, which facilitates cancer cell survival and adaptive mechanisms. Despite its critical role, the molecular landscape underlying ER stress in NEPC remains inadequately understood. Here we showed that ER stress is intimately linked to the metabolic reprogramming of NEPC cells, a process that supports their transition from adenocarcinoma to a neuroendocrine phenotype. We identified MYCN as a key driver of this process, promoting unfolded protein response (UPR) elements that enhance ER stress by increasing the efflux of calcium ions through the ER which later is absorbed by the mitochondria and assist in increasing the overall glycolytic stress, thereby adding to the extended survival and metastatic potential of an NEPC cell. Our previous studies highlighted the importance of S-nitrosylation as a protein modification that is dysregulated in high-grade PCa. In this context, structural analysis of MYCN revealed potential S-nitrosylation sites at the positions Cys4, 186, and 464, respectively. However, similar to the castration-resistant stage, this modification is hindered in NEPC due to impaired nitric oxide (NO) production from dysregulated endothelial nitric oxide synthases (eNOS). We found that exogenous NO supplementation S-nitrosylates MYCN, reducing its binding to protein molecules which are essential to assist with increasing ER stress in NEPC cells. Exogenous supplementation of NO reduced the overall tumor burden in the mice harboring orthotopic NEPC cells and reduced the metastasis to the brain and liver. In conclusion, the findings from this study enrich our understanding of the mechanisms driving the ER stress responses in NEPC phenotype and how NO supplementation could pave the way as potential therapeutics for this challenging cancer. HIGHLIGHTSO_LIEndoplasmic reticulum (ER) stress is intricately linked to metabolic reprogramming, which supports the transition from prostate adenocarcinoma to neuroendocrine prostate cancer (NEPC). C_LIO_LIMYCN increases the ER stress in NEPC cells and is correlated with increased nitroso-redox imbalance. C_LIO_LIStructural analysis reveals potential S-nitrosylation sites on MYCN. Exogenous nitric oxide (NO) supplementation induces S-nitrosylation, disrupting MYCNs role in enhancing ER stress. C_LIO_LINO supplementation reduced tumor burden and metastasis in NEPC-bearing mice, highlighting its potential as a therapeutic avenue for NEPC. C_LIO_LIExogenous NO supplementation inhibits ER stress by targeting unfolded protein response (UPR) elements and decreasing calcium ion efflux, inhibiting the glycolytic stress in NEPC. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=191 SRC="FIGDIR/small/624202v1_ufig1.gif" ALT="Figure 1"> View larger version (57K): org.highwire.dtl.DTLVardef@1fb292forg.highwire.dtl.DTLVardef@4d00f7org.highwire.dtl.DTLVardef@17a7f43org.highwire.dtl.DTLVardef@1393286_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2022

Efficacy of a Growth Hormone-Releasing Hormone Agonist in a Murine Model of Cardiometabolic Heart Failure with Preserved Ejection Fraction

Heart failure (HF) with preserved ejection fraction (HFpEF) represents a major unmet medical need owing to its diverse pathophysiology and lack of effective therapies. Potent synthetic, agonists (MR-356 and MR409) of growth hormone-releasing hormone (GHRH) improve the phenotype of models of HF with reduced ejection fraction (HFrEF) and in cardiorenal models of HFpEF. Endogenous GHRH exhibits a broad range of regulatory influences in the cardiovascular (CV) system, aging and plays a role in several cardiometabolic conditions including obesity and diabetes. Whether agonists of GHRH can improve the phenotype of cardiometabolic HFpEF remains untested and unknown. Here we tested the hypothesis that MR-356 can mitigate/reverse the cardiometabolic HFpEF phenotype. C57BL6N mice received a high fat diet (HFD) plus the nitric oxide synthase inhibitor (L-NAME) for 9 weeks. After 5 weeks of HFD+L-NAME regimen, animals were randomized to receive daily injections of MR-356 or placebo during a 4-week period. Control animals received no HFD+L-NAME or agonist treatment. Our results showed the unique potential of MR-356 to treat several HFpEF-like features including cardiac hypertrophy, fibrosis, capillary rarefaction, and pulmonary congestion. MR-356 improved cardiac performance by improving diastolic function, global longitudinal strain (GLS), and exercise capacity. Importantly, the increased expression of cardiac pro-brain natriuretic peptide (pro-BNP), inducible nitric oxide synthase (iNOS) and vascular endothelial growth factor-A (VEGF-A) was restored to normal levels suggesting that MR-356 reduced myocardial stress associated with metabolic inflammation in HFpEF. Thus, agonists of GHRH may be an effective therapeutic strategy for the treatment of cardiometabolic HFpEF phenotype.

physiology↗

bioRxiv2022

S-nitrosoglutathione Inhibits the Growth of Androgen-Receptor Dependent and Castration Resistant Prostate Cancer by Modulating FOXM1 Signaling

Castration resistant prostate cancer (CRPC) is an advanced form of prostate cancer associated with loss of androgen receptor activity and resistance to AR-targeted therapies. CRPC is often associated with higher metastasis, invasion, and proliferation. Thus, theres a strong need for additional molecular markers in CRPC, and therapies that target them directly. Transcriptomic profiling of prostate cancer patients revealed an upregulated signature specific to high-grade tumors in cell cycle progression, E2F targets, G2M checkpoint, DNA repair, Aurora Kinase B, and FOXM1 pathway. Validation in a separate cohort of neuroendocrine prostate cancer patients, the most resistant and invasive form of CRPC which lacks AR expression, showed CCP signature as a dominant driver gene set for NEPC. Moreover, high expression of mRNA targets in each of these pathways is associated with poor overall survival in NEPC patients. Gene set variation analysis revealed a strong inverse correlation between AR signaling and CCP.31, set of 31 markers associated with high proliferation, and a positive correlation between CCP.31 and NEPC signature. FOXM1, a prioritized candidate in CCP is shown to be upregulated in CRPC cell lines and human clinical sections of Gleason 9 patients. GSNO, a nitric oxide donor, known for its inhibitory effect on cell proliferation and an effective inhibitor of cell cycle checkpoints, was able to reverse CCP signature both in-vitro and in-vivo. GSNO exhibits a dependence on AR signaling in-vitro by showing mild effect on CRPC clones, but successfully inhibits tumor growth of AR-null CRPC xenografts. FOXM1 is also targeted by GSNO in-vivo and in-vitro models of both CRPC and AD prostate cancer. This establishes an important link between androgen receptor status in prostate cancer and proposes nitric oxide donors as therapeutic intervention. GSNO is effective against AR-null castration resistant prostate cancer. SignificanceNitric oxide donor, S-glutathione-transferase inhibits tumor growth of castration resistant prostate cancer, regardless of androgen receptor expression status by targeting FOXM1, a critical regulator of cell cycle progression. O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY

cancer biology↗

bioRxiv2022

Nitric oxide S-nitrosylates CSF1R to augment the action 1 of CSF1R inhibition against castration resistant prostate cancer

During progression of prostate cancer, sustained oxidative overload in cancer cells potentiates the overall tumor microenvironment (TME). Targeting the TME using colony-stimulating factor 1 receptor (CSF1R) inhibition is a promising therapy for castration-resistant prostate cancer (CRPC). However, the therapeutic response to sustained CSF1R blockade therapy (CSF1Ri) is limited as a monotherapy. We postulated that one of the causative agents for reduced efficacy of CSF1Ri and increased oxidation in CRPC is endothelial nitric oxide syntheses (eNOS). Results showed that in high grade PCa human specimens, eNOS is positively correlated with CSF1-CSF1R signaling and remains in an un-coupled state. The uncoupling disables eNOS to generate sufficient Nitric oxide (NO) that are required for inducing effective S-nitrosylation of CSF1R molecule at specific cysteine sites (Cys 224, Cys 278 and Cys 830). Importantly, we found that S-nitrosylation of CSF1R molecule at Cys 224, Cys 278 and Cys 830 sites is necessary for effective inhibition of tumor promoting cytokines (which are downstream of CSF1-CSF1R signaling) by CSF1R blockade. In this context, we studied if exogenous NO treatment could rescue the side effects of eNOS uncoupling. Results showed that exogenous NO treatment (using S-nitrosoglutathione (GSNO)) is effective in not only inducing S-Nitrosylation of CSF1R molecule, but it helps in rescuing the excess oxidation in tumor regions, reducing overall tumor burden, suppresses the tumor promoting cytokines which are ineffectively suppressed by CSF1R blockade. Together these results postulated that NO therapy could act as an effective combinatorial partner with CSF1R blockade against CRPC. In this context, results demonstrated that exogenous NO treatment successfully augment the anti-tumor ability of CSF1Ri in murine models of CRPC. Importantly, the overall tumor reduction was most effective in NO-CSF1Ri therapy compared to NO or CSF1Ri mono therapies. Moreover, Immunophenotyping of tumor grafts showed that the NO-CSF1Ri combination significantly decreased intratumoral percentage of anti-inflammatory macrophages, myeloid derived progenitor cells and increased the percentage of pro-inflammatory macrophages, cytotoxic T lymphocytes, and effector T cells respectively. Together, our study suggests that the NO-CSF1Ri combination has the potential to act as a therapeutic agent that restore control over TME and improve the outcomes of PCa patients.

cancer biology↗

bioRxiv2020

βPix sequesters IDOL and prevents LDL receptor degradation through a β2AR-regulated signaling pathway in Alport Syndrome

Alport syndrome (AS) is a rare disease of the glomerular basement membrane type IV collagen causing progressive renal failure. We reported increased accumulation of low-density lipoprotein (LDL) receptor (LDLR) and subsequent LDL cholesterol (LDL-C) uptake in renal tubular epithelial cells (TEC) in Alport mice, but the mechanisms regulating LDLR stability and function remain unknown. Here, we show that a selective {beta}2-Adrenoceptor ({beta}2AR) agonist, salbutamol, decreased LDLR levels and LDL-C uptake in Alport kidneys accompanied with reduced albuminuria and improved cardiac systolic and diastolic function. Similarly, salbutamol decreased LDL-C uptake in HK2 and HEK293 human renal epithelial cell lines, in smooth muscle cells from an X-linked hereditary nephropathy dog model (a large animal model of AS), and in TECs differentiated from AS patient-derived iPSCs. We show that the Rac1/Cdc42 guanine nucleotide exchange factor {beta}1Pix blocked {beta}2AR-induced LDLR degradation and, hence, increased LDL-C uptake. {beta}1Pix also abrogated ubiquitination and degradation of LDLR induced by the inducible degrader of the LDLR (IDOL), an E3 ubiquitin ligase that promotes lysosomal LDLR ubiquitination and degradation. We identify a multimolecular complex comprised of {beta}Pix, IDOL, and LDLR and demonstrate that {beta}Pix counteracts {beta}2AR-mediated LDLR degradation by sequestering IDOL. Our findings show {beta}Pix acts as a significant post-transcriptional regulator of IDOL-mediated LDLR degradation and identify {beta}2AR activation as a potential treatment for Alport pathology.

molecular biology↗

bioRxiv2020

S-nitrosoglutathione reductase deficiency causes aberrant placental S-nitrosylation and preeclampsia.

Preeclampsia (PE), a leading cause of maternal and fetal mortality and morbidity, is characterized by an increase in S-nitrosylated (SNO) proteins and reactive oxygen species (ROS), suggesting a pathophysiologic role for dysregulation in nitrosylation and nitrosative stress. Here we show that mice lacking S-nitrosoglutathione reductase (GSNOR-/-), a denitrosylase regulating protein S-nitrosylation, exhibit a PE phenotype, including hypertension, proteinuria, renal pathology, cardiac concentric hypertrophy, decreased placental vascularization, and fetal growth retardation. ROS, nitric oxide (NO) and peroxynitrite levels are elevated. Importantly, mass spectrometry reveals elevated placental SNO-amino acid residues in GSNOR-/- mice. Ascorbate reverses the phenotype except for fetal weight, reduces the difference in the S-nitrosoproteome, and identifies a unique set of SNO-proteins in GSNOR-/- mice. Therefore, deficiency of GSNOR creates dysregulation of placental S-nitrosylation and preeclampsia in mice, which can be rescued by ascorbate. These findings offer valuable insights and therapeutic implications for PE. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=144 SRC="FIGDIR/small/183012v3_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@1baa15corg.highwire.dtl.DTLVardef@1b79fe7org.highwire.dtl.DTLVardef@62f899org.highwire.dtl.DTLVardef@1af0b29_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical Abstract:C_FLOATNO Dysregulation in nitrosylation contributes to nitroso-redox imbalance and nitrosative stress contributing to clinical features of PE including hypertension, proteinuria, concentric hypertrophy in the heart, decrease placental vascularization and fetal growth restriction. Antioxidant treatment rescued the PE-like phenotype in the mother. C_FIG

physiology↗

bioRxiv2020

Effectiveness of Growth Hormone Releasing Hormone Agonists (GHRH A) in Chronic Kidney Disease Induced Heart Failure with Preserved Ejection Fraction

BackgroundTherapies that improve morbidity and mortality in heart failure with preserved ejection fraction (HFpEF) are lacking. Growth hormone releasing hormone analogues (GHRH-A) reverse fibrosis and improve cardiac function in ischemic and non-ischemic animal models. We tested the hypothesis that GHRH-A treatment ameliorates chronic kidney disease (CKD)-induced HFpEF in a large animal model. MethodsFemale Yorkshire pigs (n=16) underwent 5/6 nephrectomy via renal artery embolization, which induced HFpEF, and 12-weeks later received daily subcutaneous injections of GHRH-A (n=8) or placebo (n=8). Kidney function, renal and cardiac MRI, pressure-volume loops, and electrical stimulation were assessed at baseline, 12-weeks, and 16-18 weeks post-embolization. ResultsThe CKD model was confirmed by increased creatinine and BUN. HFpEF was demonstrated at 12 weeks by maintenance of ejection fraction associated with increased left ventricular mass, relative wall thickening, end-diastolic pressure (EDP), end-diastolic pressure-volume relationship (EDPVR), and tau. After 6 weeks of treatment, diastolic function improved in the GHRH-A group, evidenced by normalization of EDP (p=0.03) associated with improved diastolic compliance as measured by EDP/EDV ratio (p=0.018). ConclusionA beneficial effect of GHRH-A in diastolic function was observed in a CKD large animal model that manifests the characteristics of HFpEF. These findings have important therapeutic implications for the HFpEF syndrome.

physiology↗

bioRxiv2020

Synthetic Agonist of Growth Hormone-Releasing Hormone as Novel Treatment for Heart Failure with Preserved Ejection Fraction

ObjectiveTo test the hypothesis that the activation of the growth hormone-releasing hormone (GHRH) receptor signaling pathway within the myocardium both prevents and reverses heart failure with preserved ejection fraction (HFpEF). BackgroundHFpEF is characterized by impaired myocardial relaxation, fibrosis and ventricular stiffness. Despite the rapidly increasing prevalence of HFpEF, no effective therapies have emerged. Synthetic agonists of the GHRH receptors reduce myocardial fibrosis, hypertrophy and improve performance, independently of the growth-hormone axis. MethodsWe generated a HFpEF-like phenotype with continuous infusion of angiotensin-II (Ang-II) in CD1 mice. Mice were injected with either vehicle or a potent synthetic agonist of the growth hormone-releasing hormone, MR-356. ResultsAng-II treated animals had diastolic dysfunction, ventricular hypertrophy, and normal ejection fraction and isolated cardiomyocytes (ex vivo) exhibited incomplete relaxation, depressed contractile responses and altered myofibrillar protein phosphorylation. Calcium handling mechanisms were disturbed in cardiomyocytes from mice with HFpEF. MR-356 both prevented and reversed the development of the pathological phenotype in vivo and ex vivo. ConclusionThese findings indicate that the GHRH receptor signaling pathway represents a new molecular target to counteract HFpEF-associated cardiomyocyte dysfunction by targeting myofilament phosphorylation. Accordingly, activation of the GHRH receptor with potent synthetic GHRH agonists may provide a novel therapeutic approach to management of the HFpEF syndrome. Condensed abstractHeart failure with preserved ejection fraction (HFpEF) is characterized by a remodeled myocardium conferring ventricular stiffness and diastolic dysfunction. There are no effective therapies. Agonists of growth hormone-releasing hormone (GHRH) receptors have beneficial effects on the heart. We hypothesize that activation of GHRH receptors suppresses this HFpEF phenotype. Treatment with a synthetic agonist of GHRH, prevented the development of the pathological phenotype in a murine model of HFpEF-induced by chronic angiotensin-II infusion. These findings indicate that activation of GHRH receptors represents a novel molecular strategy to counteract HFpEF-associated cardiomyocyte dysfunction and provide a potential approach to management of HFpEF syndrome. HighlightsO_LIA synthetic growth hormone-releasing hormone agonist (GHRH-A) prevents and reverses the pathological remodeling in a mouse model of HFpEF induced by infusion of low dose Ang II. C_LIO_LIGHRH-A improves intracellular calcium handling by reducing the sarcoplasmic reticulum calcium leakage and enhancing phospholamban phosphorylation. C_LIO_LIGHRH-A treatment prevents and reverses diastolic dysfunction by enhancing the rate of sarcomere re-lengthening. C_LIO_LIActivation of the GHRH receptor with the GHRH-A, MR-356, leads to targeting myofibrillar proteins and desensitizing myofilaments in response to calcium. C_LI

cell biology↗

bioRxiv2019

Fate of developmental mechanisms of myocardial plasticity in the postnatal heart

Whether the hearts organ-founding, progenitor cell gene regulatory networks (CPC-GRNs) are sustained after birth and can be therapeutically evoked for regeneration in response to disease, remains elusive. Here, we report a spatiotemporally resolved analysis of CPC-GRN deployment dynamics, through the pan-CPC-GRN gene Isl1. We show that the Isl1-CPC-GRNs that are deployed during early cardiogenesis and generate the cardiomyocyte majority from mesoderm, undergo programmed silencing through proteasome- and PRC2-mediated Isl1 repression, selectively in the arterial pole. In contrast, we identify a neural crest (CNC)-specific Wnt/{beta}-catenin/Isl1-CPC-GRN that is deployed through the venous pole during cardiac growth and partitioning, and contributes a minority of cardiomyocytes which, in turn, expand massively to build ~10% of the biventricular myocardium. These "dorsal CNCs" continue to sporadically generate cardiomyocytes throughout postnatal growth which, however, are non-proliferative, suggesting that partitioning-like, fetal proliferation signals could be therapeutically targeted to evoke clonal expansion capacity in postnatal CNC-cardiomyocytes for heart regeneration.

developmental biology↗