Biology subjects

Shehadeh, L. A.

Publications and source records attributed to Shehadeh, L. A..

6 recordsLinked to original sources

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↗

bioRxiv2024

Sex-Specific Changes in Cardiac Function and Electrophysiology During Progression of Adenine-Induced Chronic Kidney Disease in Mice

BACKGROUNDChronic kidney disease (CKD) and cardiovascular disease (CVD) often co-exist and interact; however, notable sex-dependent differences are observed in how these conditions manifest and progress in parallel, despite men and women sharing similar risk factors. Identifying sex-specific diagnostic markers of cardiac structure and function throughout CKD progression could elucidate why the development and progression of these diseases differ by sex. METHODS AND RESULTSAdult, C57BL/6J male and female mice were subjected to a high-adenine (0.2%) diet throughout 12-weeks to induce CKD. Control mice were fed a normal chow diet. Every three weeks, electrocardiogram (ECG) and echocardiogram-based markers of cardiac physiology were evaluated. Adenine-induced CKD showed markers of left ventricular (LV) hypertrophy in male mice only. CKD males had markers indicative of LV systolic and diastolic dysfunction throughout regimen duration, worsening as disease progressed. Adenine males had a prolonged QTc and STc intervals when compared to Adenine females and Control males. Sex-dependent differences in the duration of the Speak-J marker, measured via ECG, was identified, with Adenine males showing increases in duration earlier than Adenine females compared to their Control counterparts. CONCLUSIONSIn this study, we identified sex-dependent differences in cardiac structure, function, and electrophysiology in a mouse model of CKD-induced CVD throughout disease progression. We found that male mice are more prone to developing LV hypertrophy, systolic dysfunction, and diastolic dysfunction, with significant increases in ECG markers indicative of ventricular dysfunction observed in adenine-treated males at late stages of the disease. Additionally, we identified a new ECG parameter, Speak-J duration, that highlights sex-specific cardiac electrophysiological changes, demonstrating the models utility in studying sex-dependent cardiac differences.

pathology↗

bioRxiv2024

Sarcomeric SRX:DRX Equilibrium in Alport and LDLR/P407 Mouse Models of HFpEF.

Cardiac myosin energetic states that regulate heart contractility define interactions of myosin cross-bridges with actin-containing thin filaments have been functionally linked with the pathology of hypertrophic cardiomyopathy (HCM). In particular, the balance between the disordered relaxed (DRX) and super relaxed (SRX) states that correlate respectively with enhanced force and energy conservation significantly determine myocardial performance and energy utilization. Compelling evidence suggests that a balanced SRX and DRX states proportion is a prerequisite for long-term cardiac health. Whereas roles for altered SRX: DRX proportions in HCM have been studied in depth, the mechanics of sarcomeric dysfunction and SRX: DRX proportions have not been reported in models of acquired heart failure (HF) including HF with preserved ejection fraction (HFpEF). Here, we quantified SRX andDRX myosin populations in two mouse models of HFpEF, including Alport and LDLR/P407 mice that represent cardiorenal/hypertensive and cardiometabolic/hyperlipidemic mouse models of HFpEF, respectively. We report significant changes in the SRX:DRX in both HFpEF mouse models, with an increased DRX state associated with Alport mice and a stabilized SRX state associated with LDLR/P407 mice. These findings correlate respectively with the hypercontractility and metabolic dysregulation with bradycardia phenotypes.

cell biology↗

bioRxiv2022

Methylene Blue Is a Nonspecific Protein-Protein Interaction Inhibitor with Potential for Repurposing as an Antiviral for COVID-19

We have previously identified methylene blue, a tricyclic phenothiazine dye approved for clinical use for the treatment of methemoglobinemia and used for other medical applications, as a small-molecule inhibitor of the protein-protein interaction (PPI) between the spike protein of the SARS-CoV-2 coronavirus and ACE2, the first critical step of the attachment and entry of this coronavirus responsible for the COVID-19 pandemic. Here, we show that methylene blue concentration-dependently inhibits this PPI for the spike protein of the original strain as well as for those of variants of concerns such as the D614G mutant and delta (B.1.617.2) with IC50 in the low micromolar range (1-5 M). Methylene blue also showed promiscuous activity and inhibited several other PPIs of viral proteins (e.g., HCoV-NL63 - ACE2, hepatitis C virus E - CD81) as well as others (e.g., IL-2 - IL-2R) with similar potency. This non-specificity notwithstanding, methylene blue inhibited the entry of pseudoviruses bearing the spike protein of SARS-CoV-2 in hACE2-expressing host cells both for the original strain and the delta variant. It also blocked SARS-CoV-2 (B.1.5) virus replication in Vero E6 cells with an IC50 in the low micromolar range (1.7 M) when assayed using quantitative PCR of the viral RNA. Thus, while it seems to be a promiscuous PPI inhibitor with low micromolar activity and it has a relatively narrow therapeutic index, methylene blue inhibits entry and replication of SARS-CoV-2, including several of its mutant variants, and has potential as a possible inexpensive, broad-spectrum, orally bioactive small-molecule antiviral for the prevention and treatment of COVID-19.

pharmacology and toxicology↗

bioRxiv2021

Soluble guanylate cyclase stimulation mitigates skeletal and cardiac muscle dysfunction in a mdx model of Duchenne muscular dystrophy

The impairment of neuronal nitric oxide synthase (nNOS) signaling contributes to disease pathology in the muscle wasting disorder Duchenne muscular dystrophy (DMD). nNOS signal propagation occurs through nitric oxide sensitive soluble guanylate cyclase (sGC), a critical source of cyclic guanosine monophosphate (cGMP) in muscle. Although both nNOS and sGC activity are impaired in DMD patients, little is known about sGC as a therapeutic target. In this study, we tested the hypothesis that stimulating sGC activity with the allosteric agonist BAY41-8543 mitigates striated muscle pathology in the mdx4cv mouse model of DMD. In contrast to DMD patients, mdx mice exhibited greater basal sGC activity than wild type controls with preservation of cGMP levels due partly to upregulation of sGC in some muscles. Stimulating sGC activity in mdx mice with BAY41-8543 substantially reduced skeletal muscle damage, macrophage densities and inflammation and significantly increased resistance to contraction-induced fatigue. BAY41-8543 also enhanced in vivo diaphragm function while reducing breathing irregularities suggesting improved respiratory function. BAY41-8543 attenuated cardiac hypertrophic remodeling, fibrosis and diastolic dysfunction including left atrium enlargement in aged mdx mice. Overall, sGC stimulation significantly mitigated skeletal and cardio-respiratory dysfunction in mdx4cv mice. Importantly, this study provides compelling pre-clinical evidence supporting sGC as a novel target in DMD and the repurposing of FDA-approved sGC stimulators, such as riociguat and veraciguat, as a novel therapeutic approach for DMD.

physiology↗

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↗