bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 042: Radiation-Associated Cardiovascular Risks for Future Deep-Space Missions
Authors: Yan Xinhua , Sasi Sharath P , Gee Hannah , Lee Juyong , Yang Yongyao , Song Jin , Carrozza Joseph , Goukassian David A 
Published: July 2021

During the future Moon and Mars missions astronauts will be exposed to space radiation (IR) for extended time. The effect of cosmic IR during and after space flights on cardiovascular (CV) system is unknown. Nine-month old C57BL/6N male mice were IR once with proton 50 cGy or 56Fe 15 cGy, both at 1 GeV/nucleon. We evaluated IR-induced biological responses - underlying molecular mechanisms, calcium handling, signal transduction and gene expression. Cardiac function was assessed by echocardiography and hemodynamic measurements.
Left ventricular end diastolic pressure (LVEDP) was increased in 56Fe mice 1 and 3 months post-IR (p<0.001). One month post-IR, compared to control, proton- and 56Fe-IR sarcolemmal Na+-Ca2+ exchanger (NCX) (p<0.007) and sarco(endo)plasmic reticulum calcium-ATPase (SERCA2a, p<0.02) were both increased more than 200% and p-p38 was decreased 400% (p<0.05), suggesting activation of compensatory mechanisms in [Ca2+]i handling in these hearts.
By 3 months, compared to control, proton- and 56Fe-IR hearts SERCA2a and p-Creb1 was decreased 200-500% (p<0.02), suggesting reduced capacity in intracellular [Ca2+]i handling, suggesting that [Ca2+]i handling dysfunction combined with LVEDP increase in 56Fe-IR may be due to prolonged activation of compensatory mechanisms that lead to changes in SERCA2a and p-Creb1 levels.
By 10 months, compared to control, LVESP was decreased in proton- and 56Fe-IR (p<0.03), suggesting IR-associated decrease in contractile function. However, compared to age-matched controls (18 months), the LVEDP was increased (p<0.05) and dP/dt Min was decreased (p<0.02) in proton-IR but not 56Fe-IR mice. This data suggests that after 10 months proton- but not 56Fe-IR affects considerably contractile and relaxation functions during aging.
Our longitudinal 1, 3 and 10 months studies reveal that a single full body low dose proton- and 56Fe-IR have long-lasting negative effect on heart homeostasis during aging. The divergent effects of low dose proton vs. 56Fe-IR on heart function during aging suggest significantly different biological mechanisms responsible for this ion-dependent dichotomy over 10 months post-IR and necessitate further studies into underlying molecular mechanisms.
Abstract 183: Small Molecule Gβ? Inhibition Reduces Pathologic Activation of Cardiac Fibroblasts
Authors: Travers Joshua G , Kamal Fadia A , Blaxall Burns C 
Published: July 2021

Heart failure (HF) is a devastating disease characterized by cardiac hypertrophy, fibrosis and inflammation. Excess signaling through Gβγ subunits leads to chronic β-adrenergic receptor (β-AR) downregulation, mediated predominantly by GRK2 in complex with PI3Kγ. Our recent work has demonstrated the therapeutic potential of the small molecule Gβγ-GRK2 inhibitor Gallein in limiting HF progression. Chronic activation of cardiac fibroblasts (CF), critical yet underappreciated myocardial cells, is a key contributor to pathologic cardiac remodeling. We hypothesized that Gβγ-GRK2 inhibition may limit pathologic CF activation.
CFs were stimulated with Isoproterenol (Iso, β-AR agonist), AngII, or vehicle (V), +/- Gβγ inhibition for 24hr. Gallein treatment attenuated the induction of αSMA expression, a marker of pathologic CF activation, and two inflammatory cytokines, IL-1β and IL-6 in response to these pathologic stimuli (Iso, AngII), as assessed by real time PCR. This data suggest that Gallein treatment may reduce pathologic CF activation. Iso stimulation also enhances the phosphorylation of Akt, a kinase downstream of PI3Kγ known to be involved in cellular proliferation. Gβγ inhibition mitigated this induction, decreasing Akt phosphorylation >60% in response to Iso. This phenomenon was also observed in failing human CFs, in which Gallein decreased Akt phosphorylation >70%.
We have recently demonstrated that the protease-activated receptor 1 (PAR1), a GPCR we have implicated in cardiac hypertrophy, is transactivated via chronic β-AR stimulation by induction of MMP-13, a protease we have found to be elevated in HF. Recent data from our lab and others have demonstrated that PAR1 is the most abundantly expressed GPCR in CFs, and that its stimulation in CFs may be pathologic. Interestingly, Gβγ inhibition treatment reduced PAR1 cleavage and activation in response to chronic Iso.
In summary, small molecule Gβγ inhibition appears to reduce pathologic CF activation. The reduction in β-AR-mediated PAR1 cleavage reveals an alternative role for Gβγ inhibition in preventing CF activation and proliferation. These data suggest a potential therapeutic role for small molecule Gβγ inhibition in limiting pathologic CF activation and cardiac hypertrophy.
Abstract 280: Deficiency of FKBP12 in the Heart Leads to Impaired Contractility and Pregnancy Induced Cardiomyopathy
Authors: Oakes Joshua , Hamilton Susan 
Published: July 2021

FK506 Binding Proteins (FKBPs) are a family of cis-trans prolyl isomerases that bind rapamycin and FK506. FKBP12 and 12.6 interact with ryanodine receptors (RyR), homotetrameric transmembrane ion channels that regulate Ca2+ release from the sarcoplasmic reticulum (SR). FKBP12 interacts with RyR1 in skeletal muscle and FKBP12.6 interacts with RyR2 in cardiac muscle to regulate the Ca2+ leak properties of these channels. Recently it has been suggested that FKBP12 also plays a role in regulating RyR2 activity. Using mice with a cardiac specific deficiency in FKBP12, we analyzed the role of FKBP12 in cardiac function.
We found that both male and female mice with a α-MyHC Cre/Lox mediated deficiency in FKBP12 in the heart (FKBP12 KD) developed a mild dilated cardiomyopathy, with enlarged left ventricular diameter both during systole and diastole, decreased ejection fraction and decreased fractional shortening. To elucidate the mechanism for these effects we assessed Ca2+ sparks in isolated cardiomyocytes. We found an increase in both Ca2+ spark frequency and spark amplitude in FKBP12 cardiac deficient mice without a change in spark duration. Despite a mild phenotype in adult mice, we found that approximately 25% of all pregnancies (26/106) in the FKBP12 deficient mice resulted in the mothers dying following the birth. Autopsies show that these cardiac specific FKBP12 deficient mice had increased heart weight and significantly dilated ventricles compared to female Cre mice. Our data suggest that a cardiac specific deficiency in FKBP12 leads to the development of pregnancy induced cardiomyopathy. Echocardiography on FKBP12 deficient mice one day after giving birth found that there was no significant difference in ejection fraction or fractional shortening compared to α-MyHC Cre control mice. FKBP12 deficient females, however, had larger hearts and 50% (2/4) displayed heart failure and died. In conclusion, we show that FKBP12 does indeed alter Ca2+ handling in the heart and that a loss of FKBP12 leads to the development of pregnancy induced cardiomyopathies in females.
Abstract 301: Targeting Mixed Lineage Kinases in pathological cardiac fibroblast activation and intercellular communication
Authors: Schulz Emily M , Martin Melissa L , Goodfellow Val S , Dewhurst Stephen , Gelbard Harris A , Blaxall Bruns C 
Published: July 2021

Cardiovascular disease (CVD) and the final clinical iteration, heart failure (HF), affect more than 82 million Americans yearly, affects >5.7 million). Although the cardiac myocyte has long been the focus of cardiac cellular research, our lab and others have demonstrated that pathological activation of cardiac fibroblasts (CF) after onset of disease or cardiac injury is also a key player in HF pathogenesis. Pathologic activation of CFs causes a release of various paracrine and autocrine factors that target cardiomyocytes (CM), local inflammatory cells and the CFs themselves. Elucidating the mechanisms involved in pathological ‘support cell (CF)’- ‘functional cell (CM)’ communication may hold therapeutic promise.
Mixed lineage kinase 3 (MLK3) is a stress activated mitogen-activated protein kinase kinase kinase (MAPKKK) involved in pro-apoptotic pathways. Inhibition of MLK3 in HAND results in the attenuation of microglial cell activation, preservation of neuronal function and synaptic structures. The parity between microglia-neuron communication and CF-CM communication and the effects of pathological activation on the respective support cells for each tissue type suggested a role for MLK3 in aberrant CF-CM cross-talk associated with the development and progression of HF. Preliminary data in mice subjected to a pharmacological model of HF (chronic isoproterenol) that were treated with a small molecule inhibitor (URMC-099) of MLK3 demonstrated a reduction in the development of myocardial fibrosis compared to vehicle treated animals. Additionally, small molecule MLK3 inhibition attenuated the development of myocardial hypertrophy as measured by heart weight: body weight and heart weight: tibia length ratios. Studies in cultured neonatal rat ventricular fibroblasts (NRVF) demonstrated that small molecule MLK3 inhibition attenuated CF activation and transition to a myofibroblast phenotype, including reductions of pathologic CF markers such as α-SMA, IL-6, IL-1β, and others. Our data demonstrate that MLK3 plays an important role in pathologic CF-CM communication and myocardial hypertrophy, and suggest that small molecule inhibition of MLK3 holds therapeutic promise for HF.
Abstract 313: STIM1 Silencing Reverses Pressure-overload Induced Cardiac Hypertrophy In Mice
Authors: Bénard Ludovic O , Matasic Daniel S , Keck Mathilde , Lompré Anne-Marie , Hajjar Roger J , Hulot Jean-Sébastien 
Published: July 2021

STromal Interaction Molecule 1 (STIM1), a membrane protein of the sarcoplasmic reticulum, has recently been proposed as a positive regulator of cardiomyocyte growth by promoting Ca2+ entry through the plasma membrane and the activation of Ca2+-mediated signaling pathways.
We demonstrated that STIM1 silencing prevented the development of left ventricular hypertrophy (LVH) in rats after abdominal aortic banding.
Our aim was to study the role of STIM1 during the transition from LVH to heart failure (HF). For experimental timeline, see figure.
Transverse Aortic Constriction (TAC) was performed in C57Bl/6 mice. In vivo gene silencing was performed using recombinant Associated AdenoVirus 9 (AAV9). Mice were injected with saline or with AAV9 expressing shRNA control or against STIM1 (shSTIM1) (dose: 1e+11 viral genome), which decreased STIM1 cardiac expression by 70% compared to control.
While cardiac parameters were similar between the TAC groups at weeks 3 and 6, shSTIM1 animals displayed a progressive and total reversion of LVH with LV walls thickness returning to values observed in sham mice at week 8. This reversion was associated with the development of significant LV dilation and severe contractile dysfunction, as assessed by echography. Hemodynamic analysis confirmed the altered contractile function and dilation of shSTIM1 animals. Immunohistochemistry showed a trend to more fibrosis. Despite hypertrophic stimuli, there was a significant reduction in cardiac myocytes cross-section area in shSTIM1-treated animals as compared to other TAC mice.
This study showed that STIM1 is essential to maintain compensatory LVH and that its silencing accelerates the transition to HF.
Abstract 315: Mice With Cardiac-restricted Overexpression Of Myozap Are Sensitized To Biomechanical Stress And Develop A Protein-aggregate Associated Cardiomyopathy
Authors: Frank Derk , Poyanmehr Reza , Rangrez Ashraf , Kuhn Christian , Grund Christine , Franke Werner W , Frey Norbert 
Published: July 2021

The intercalated disc (ID) is a major component of the cell-cell contact structures of cardiomyocytes ensuring their electro-mechanical coupling. In previous work, we could identify and characterize Myozap, a novel cardiac-enriched ID protein, which interacts with several other ID proteins.
We could now show in cardiomyocytes that overexpression of Myozap activates the Rho-dependent SRF pathway. Consistently, RNAi-mediated Myozap knockdown blocked Rho-mediated SRF activation linking the ID to gene regulation and actin dynamics.
For further analyses of Myozap’s functions in vivo, we generated a mouse model with cardiac overexpression of Myozap cDNA (αMHC promoter). 1 year old mice developed cardiomyopathy with significant hypertrophy (heart weight/tibia length +43%, p<0.01, n=8-10) as well as LV dilation (LVEDD +20%, p<0.01) and a trend towards LV dysfunction (fractional shortening 50% vs. 42%, n=10, p=0.07). Consistently, these mice displayed upregulation of the hypertrophy-associated gene program (nppa 4.3-fold, p<0.001, and nppb 2.2-fold, p<0.01, n=7-9).
On the ultrastructural level, we could detect bulky aggregates containing Myozap, desmoplakin and other ID proteins. This aggregate-associated pathology closely resembled the changes in the hearts of patients suffering from desminopathies. Interestingly, desmin was not detectable in the aggregates in MyozapTG mice, but appeared to be displaced from the ID. Further molecular analyses in the aged mice also revealed dysregulation of typical members of the unfolded protein response (UPR) associated with upregulation of UPR-related apoptosis (cleaved caspase 12).
Functionally, pressure overload via transverse aortic constriction (TAC) caused exaggerated cardiac hypertrophy (heart/body weight 7.9 mg/g in Myozap TG-TAC vs. 5.6 mg/g in WT-TAC, n=11 each group, p=0.002) and loss of contractility (fractional shortening of 15.3% in Myozap TG-TAC vs. 33.0% in WT-TAC, n=11 each group, p<0.001). Similarly, a physiological stimulus (voluntary running) led to a less dramatic but significant premature LV dysfunction.
In conclusion, Myozap overexpression offers new insights in the pathogenesis of protein aggregate-associated cardiomyopathies.
Abstract 316: A Potential Mechanism Involving mTOR For The Expression Of CTGF In Agonist-stimulated Adult Cardiomyocytes
Authors: Sundararaj Kamala P , Balasubramanian Sundaravadivel , Pleasant Dorea , Kuppuswamy Dhandapani 
Published: July 2021

Cardiac hypertrophy ensues as a response to multiple stimuli, such as mechanical stress, neurohumoral activation, growth factors and cytokines. Connective Tissue Growth Factor (CTGF), a potent fibrogenic cytokine, regulates a wide range of biological functions including ECM deposition, wound repair, angiogenesis, migration, differentiation, survival and proliferation. While CTGF overexpression in fibroblasts has been shown to be responsible for fibrosis in various organs, controversy exists about the source of CTGF. Since interstitial fibrosis contributes to ventricular wall stiffness and impairs diastolic function, understating how key factors such as CTGF are expressed and released for the genesis of fibrosis in the hypertrophying heart is important to develop new treatment options. To this end, we explored the signaling pathway(s) involved in the phenylephrine (PE), a hypertrophic agonist, induced expression of CTGF by cardiomyocytes (CMs). Since mammalian target of rapamycin (mTOR) is reported to regulate PE-induced hypertrophic signaling, we hypothesize that mTOR plays a role in PE induced CTGF expression in CMs.
To test if CMs produce CTGF, we treated adult feline CMs with phenylephrine. PE stimulated CTGF mRNA expression in a dose and time dependent manner. mTOR forms two distinct complexes, mTORC1 and mTORC2. Whereas both complexes are sensitive to a pharmacological inhibitor Torin1, only mTORC1 is sensitive to Rapamycin inhibition. Our results indicate that PE stimulated CTGF expression could be substantially enhanced by torin1 pretreatment of CMs. Moreover, shRNA mediated silencing of Rictor in CMs, one of the components of mTORC2, significantly augmented the PE induced CTGF mRNA expression. But mTORC1 inhibition using Rapamycin or activation of its downstream target S6K1 using Rapamycin resistant S6K1 adenovirus had no impact in PE -stimulated CTGF expression. The same trend was also observed in the level of secreted CTGF. In conclusion, these results strongly indicate that mTORC2 plays a repressive role in CTGF mRNA expression in adult CMs, and that the loss of such repression in PO myocardium might be a potential mechanism for the onset of cardiac fibrosis in hypertrophying myocardium.
Abstract 147: δ-opioid Receptor Activation Increases Nrf2 Nuclear Translocation And Stabilizes Mitochondrial Membrane Potential Of Hypoxic Cells
Authors: Cao Shan , Chen Tao , Chao Dongman , Wen Guoqiang , Balboni Gianfranco , Xia Ying 
Published: July 2021

Conditions that limit O2 supply for a prolonged period lead to cardiac injury. However, current strategies against hypoxic cardiac injury are limited in clinical settings. It is of utmost importance to find novel clues for protecting cells from hypoxic injury. Our work has recently shown that δ-opioid receptor (DOR) activation strongly regulates microRNA expression in the heart exposed to prolonged hypoxia, suggesting a role of DOR in cardiac adaptation to hypoxic stress. To further determine DOR's action on cell survival under hypoxia and the underlying mechanisms, we exposed HEK293t cells to hypoxia for a prolonged period and then investigated cellular viability and changes in mitochondrial membrane potential and the nuclear factor erythroid 2-related factor 2 (Nrf2), which are thought to be involved in the regulation of cell survival under hypoxia. Our data show that prolonged hypoxia (0.5% of O2 for 16-48 hours) caused serious cellular injury. DOR activation with UFP-512, a potent and specific DOR agonist, prevented the collapse of mitochondrial membrane potential and markedly attenuated cell injury in the hypoxic condition. The DOR-mediated protection was largely reversed by DOR antagonism with naltrindole. Furthermore, we observed that DOR activation increased Nrf2 translocation from cytoplasm to nucleus. The DOR-mediated cytoprotection was largely abolished by the "knock-down" of Nrf2. Our results suggest that DOR activation increases Nrf2 nuclear translocation and stabilizes mitochondrial membrane potential during the process of cellular protection against hypoxic stress.
SC and TC are equal contributors.
Supported by HD-034852, AT-004422, NSFC 81060096 and 81260204.
Abstract 186: Identification of Novel Protein Kinase G I Alpha Antiremodeling Substrates in the Myocardium
Authors: Blanton Robert M , Baumgartner Robert A , Thoonen Robrecht , Giovanni Shewit , Govindan Suresh , Aronovitz Mark , Sadayappan Sakthivel , Kass David A , Karas Richard H 
Published: July 2021

Protein kinase G I α (PKGIα) inhibits cardiac remodeling, and this effect requires the PKGIα leucine zipper (LZ) binding domain. However, PKGIα LZ-dependent cardiac substrates remain poorly understood. Clinical trials of PKGI activating drugs have been limited to date by hypotension arising from vascular PKGI activation. Therefore, we explored downstream PKGIα substrates in the heart which may inhibit remodeling, yet circumvent the hypotensive effects of systemic PKGI activation. A screen for PKGIα LZ-interacting proteins identified: 1)cardiac myosin binding protein-C (cMyBP-C) and 2) mixed lineage kinase 3 (MLK3).
cMyBP-C is a cardiac myocyte protein known to inhibit remodeling when phosphorylated. Co-precipitations with cGMP-conjugated beads confirmed the PKGIα-cMyBP-C interaction. Purified PKGIα phosphorylated cMyBP-C in vitro at Ser-273, Ser-282, and Ser-302. cGMP induced cMyBP-C phosphorylation at these sites in COS cells transfected with WT PKGIα, but not in cells transfected with either LZ mutant PKGIα or kinase-inactive PKGIα. In hearts of 9 month old PKGIα Leucine Zipper mutant mice, which have LV hypertrophy (LVH) and diastolic dysfunction, we observed decreased phosphorylated cMyBP-C as well as decreased total cMyBP-C, compared with WT littermate hearts.
We next tested the effect of MLK3, which interacts with PKGIα in the heart, on remodeling in vivo. We performed 7 day Transaortic Constriction (TAC) on MLK3 KO mice and WT littermates (n=5 shams, 8 TAC per genotype). MLK3 KO TAC mice had increased LVH (LV mass/tibia length 71.1 ± 2.7 g/cm KO TAC vs 62.1 ± 2.7 WT TAC; p<0.05). Further, MLK3 KO mice developed overt CHF compared with WT littermates (LV end diastolic pressure 14.8 ± 1.9 mmHg KO TAC vs 7.7 ± 2.1 WT TAC, p <0.05), as well as accelerated decrements in LV preload recruitable stroke work (36.6 ± 11.9 mmHg/ul KO TAC vs 94.6 ± 12.9 WT TAC, p<0.05) and min dP/dt (-6292 ± 519 mmHg/s KO TAC vs −8157 ± 554 WT TAC , p <0.05). We observed no differences in LV structure or function between sham genotypes.
These studies reveal 2 novel PKGIα anti-remodeling substrates, and they support that exploring PKGIα substrates in the heart may identify novel therapeutic targets to inhibit cardiac remodeling but avoid excessive PKGI induced vasodilation.
Abstract 289: Retinoblastoma Gene Deletion Promotes Cardiac Dysfunction, Fibrosis and Apoptosis in Response to Pressure Overload
Authors: Ammann Paul B , Yamamoto Takanobu , Zhai Peiyong , Sadoshima Junichi 
Published: July 2021

The retinoblastoma (Rb) protein is a universal cell cycle regulator in mammals. When the Rb protein is phosphorylated by Cyclins/Cdks, it dissociates from E2F, and Rb-dependent E2F repression is subsequently inactivated. Furthermore, the Rb protein has also been implicated in the regulation of cardiac hypertrophy and apoptosis in cardiomyocytes (CMs).
To elucidate the role of Rb in response to mechanical stress, we conducted transverse aortic constriction (TAC) in cardiac-specific Rb knockout mice (cRb-KO) in vivo (C57BL/6J). Cardiac-specific deletion of Rb was achieved by crossing Rb flox/flox mice with αMHC-Cre mice.
Under basal conditions, 3- to 5-month-old cRb-KO mice showed increased heart weight (HW) (left ventricular weight/ tibial length (TL): 5.93 ± 029 vs. 4.76 ± 0.14, p< 0.01), increased apoptosis as determined by TUNEL staining (0.12% vs. 0.02%, p< 0.05) and a trend towards cardiac dysfunction (-dP/dt: 4320 ± 388 vs. 5933 ± 489 mmHg/sec, p < 0.05) compared to control mice (Rb flox/flox)
Following 2 weeks of TAC, cRb-KO mice showed increased heart weight (HW/TL: 8.58 ± 0.35 vs. 7.50 ± 0.24, p < 0.05), cardiac dysfunction (ejection fraction (EF): 51.1% ± 4.0 vs. 74.3% ± 0.9, p < 0.01) , increased apoptosis as determined by TUNEL staining (0.48% vs. 0.05%, p < 0.01) and increased fibrosis as determined by Masson’s Trichrome staining (1.84% vs. 1.03%, p < 0.05) compared to Rb flox/flox mice after TAC.
In response to 4 weeks of TAC, cRb-KO mice showed increased heart weight (HW/TL: 12.93 ± 085 vs. 9.32 ± 0.34, p < 0.01), lung weight (LW) (LW/TL: 18.35 ± 2.66 vs. 10.21 ± 1.93, p < 0.01), cardiac dysfunction (EF: 34.5% ± 8.3 vs. 64.3% ± 8.9, p < 0.01), increased apoptosis as determined by TUNEL staining (0,42% vs. 0,18%, p < 0.05) and increased fibrosis as determined by Masson’s Trichrome staining (4.2 % vs. 1.1 %, p < 0.05) compared to Rb flox/flox mice after TAC.
Pressure gradients were similar between the cRb-KO mice submitted to 2 and 4 weeks of TAC and their respective controls.
In conclusion, our results suggest that endogenous Rb plays an important role in mediating cell survival in CMs and negatively regulates cardiac hypertrophy at baseline. Furthermore, we showed that the Rb protein is important for the maintenance of cardiac function in response to pressure overload.