bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 267: Preserved Cardiac Contractility and Venous Return in Beta-arrestin2 Transgenic Mice During Sepsis With Insufficient Resuscitation
Authors: Yan Hui , Denney James , Li Hui , Daniels Christopher , Singh Krishna , Chua Balvin , Caudle Yi , LeSage Gene , Yin Deling
Published: July 2021

β-arrestin 2 is a negative regulator of inflammation and a protective signaling transducer in acute heart injury. In this study, using echocardiography and Millar Pressure-Volume systems, we found that heart dysfunction accompanied with hemodynamic instability occurred rapidly after experimental sepsis with insufficient resuscitation in wild type and β-arrestin 2 knock out mice but not in β-arrestin 2 transgenic mice. β-arrestin 2 overexpression is associated with preserved preload, cardiac output, systolic contractility and diastolic elasticity after cecal ligation and puncture (CLP). Furthermore, β-arrestin 2 overexpression up-regulated IL-6/IL-6R/gp130/STAT3 anti-apoptotic signaling through suppressing p38 activation and subsequently inhibiting phosphorylation of membrane bound gp130, the signal transducer part of IL-6 receptor complex. In conclusion, β-arrestin 2 is a crucial cardiac function regulator in sepsis.
Abstract 269: Sirt-6 Deficiency Impairs Wound Healing in Diabetic (db/db) Mice Through Enhancement of Nf-kb Dependent Transcriptional Activity
Authors: Thandavarayan Rajarajan A , Joladarashi Darukeshwara , Suresh Babu Sahana , Jeyabal Prince , Krishnamurthy Shashirekha , Garikipati Venkata N , Verma Suresh K , Kishore Raj , Krishnamurthy Prasanna
Published: July 2021

Delayed wound healing is one of the major complications in diabetes and is characterized by chronic proinflammatory response, and abnormalities in angiogenesis and collagen deposition. Sirtuin family proteins regulate numerous physiological processes, including those involved in promotion of longevity, DNA repair, glycolysis and inflammation. However the role of sirtuin 6 (SIRT6), a NAD+-dependent nuclear deacetylase, in wound healing specifically under diabetic condition remains unclear. To analyze the role of SIRT6 in cutaneous wound healing, paired 6 mm stented wound were created in diabetic db/db mice and injected siRNA against SIRT6 in the wound margins (transfection agent alone and non-sensed siRNA served as controls). Wound time to closure was assessed by digital planimetry, and wounds were harvested for histology, immunohistochemistry and western blotting. SIRT6-siRNA treated diabetic wound showed impaired healing, which was associated with reduced capillary density when compared to control treatment. Interestingly, SIRT6 deficiency decreased VEGF expression in the wounds. Furthermore, SIRT6 ablation in diabetic wound promotes NF-kB activation resulting in increased expression of proinflammatory marker and oxidative stress. Collectively, our findings demonstrate that loss of SIRT6 in cutaneous wounds promotes proinflammatory response by increasing NF-kB activation, oxidative stress and decrease in angiogenesis in the diabetic mice. Based on these findings, we speculate that activation of SIRT6 signaling might be a potential approach for promoting wound healing in diabetics.
Abstract 272: Hyperhomocysteinemia Potentiated the Impairment of Hydrogen Sulfide-induced Endothelium-derived Hyperpolarization-mediated Vascular Relaxation in Diabetic Db/db Mice
Authors: Cheng Zhongjian , Jiang Xiaohua , Shen Xinggui , Fang Pu , Kishore Raj , Kevil Chris
Published: July 2021

Background:
Cumulative evidence indicates that plasma homocysteine (Hcy) level is positively correlated with cardiovascular mortality in Type 2 diabetic patients.

Aims:
To explore the effects and mechanisms of elevated plasma Hcy level[[Unable to Display Character: ―]] hyperhomocysteinemia (HHcy) on endothelial function in db/db mice.

Methods and Results:
HHcy was induced in diabetic db/db and non-diabetic db/+ mice fed with a high methionine diet (HM, 2% methionine) for 8 weeks (plasma tHcy=54.31±5.4 and 34.21±4.15 μM). Endothelial function was examined in small mesenteric arteries (SMA) using myographs. In non-diabetic mice, HHcy did not change vascular relaxation to acetylcholine (Ach); whereas, nitric oxide (NO)- and prostacyclin (PGI2)-mediated relaxation to Ach were impaired. Interestingly, endothelium-derived hyperpolarization factor (EDHF)-mediated relaxation to Ach was improved. In diabetic mice, HHcy potentiated the impairment of NO-, PGI2- and EDHF-mediated relaxation to Ach. Moreover, sodium hydrogen sulfide (NaHS), a donor of hydrogen sulfide (H2S), induced EDHF-mediated relaxation which was impaired in diabetic mice and potentiated by HHcy. NS309, a non-specific calcium-activated potassium channel (Kca) activator, significantly improved H2S- and Ach-induced EDHF-mediated relaxation in diabetic mice with HHcy. Tram-34, an intermediate conductance Kca (IK) blocker, but not small conductance Kca blocker apamin, diminished HHcy-induced impairment of EDHF-mediated relaxation in diabetic mice, suggesting that IK inactivation plays a major role. Free sulfide was decreased in plasma and SMA of diabetic mice which was potentiated with HHcy. Superoxide generation was increased and potentiated by HHcy in lung ECs from diabetic mice. Moreover, PEG-SOD improved vascular relaxation in diabetic mice with HHcy. Finally, tyrosine nitration of IK was increased in human cardiac microvascular endothelial cells (ECs) treated with either D-glucose (25 mM) or DL-Hcy (500 μM) for 48h, which was potentiated by a combination of D-glucose and DL-Hcy.

Conclusions:
H2S is a major EDHF in resistant arteries in mouse. H2S-contributed EDHF-mediated vascular relaxation was impaired in diabetes and was potentiated by HHcy via oxidative stress and IK inactivation.
Abstract 301: A Novel Tram Stent Method in Treatment of Coronary Bifurcation Lesions
Authors: Arokiaraj Mark C
Published: July 2021

Aims:
A novel coronary stent was designed for the treatment of coronary bifurcation lesion, and it was investigated for its performance by finite element analysis.

Methods and Results:
A coronary bifurcation model was created with the proximal vessel of 3.2 mm diameter, and the distal vessel after the side branch (2.3 mm) was 2.7 mm. A novel stent was designed with connections that had a profile of a tram. Laser cutting and shape setting of the stent was performed, and thereafter the stent was deployed over a balloon. The contact pressure, stresses on the artery wall, stresses on the stent, the maximal principal log strain of the main artery and the side-branch were studied. The finite element study was performed in Abaqus, Simulia.The stresses on the main branch and the distal branch were minimally increased after deployment of this novel stent. The side branch was preserved, and the stresses on the side branch were lesser. At the confluence of the bifurcation on either side of the side branch origin the Von Mises stresses were marginally increased. However, the stresses at the bifurcation were significantly lesser than the stresses of the currently existing techniques used in the treatment of bifurcation lesions. Further, the tram area was studied parametrically to reduce the stresses. A firm lesion model with a stenosis of 80% was then created with a discrete lesion in side-branch and the main vessel. The stent was deployed in the main branch and the side branch was stented at the ostium. The stresses at the bifurcation and the main vessel was further reduced and the stent deployed well.

Conclusions:
There is a potential for a novel Tram-stent method in the treatment of coronary bifurcation lesions.
Abstract 302: Four-and-a-half Lim Domain Protein-1 Upregulation via an Alternate Start Site Prepares the Left Atrium for Birth
Authors: Cubero Salazar Ilton M , Axelsson Anna , Wakimoto Hiroko , DeLaughter Daniel , Christodoulou Danos , Jiang Jianming , Burke Michael , Benson Craig , Gorham Joshua , Depalma Steve , Chen Ju , Mukundan Srinivasan , Jerosch-Herold Michael , Seidman Christine E , Seidman Jonathan G
Published: July 2021

Four-and-a-half-LIM-domain protein-1 (FHL1) participates in the heart’s response to biomechanical stress during pathological states. Normally, the basal isoform,
bFhl1
, predominates in non-stressed states. In pathology, a change in start site leads to expression of the induced isoform,
iFhl1
, which is 16 amino acid residues longer than bFHL1. We have studied the expression and role of
Fhl1
during normal cardiac development. The shift from fetal to neonatal circulation signifies new stress for the heart, and provides a unique opportunity to study the role FHL1 in the setting of physiological stress. We hypothesize that selective
iFhl1
upregulation during this transitional period prepares the heart for the stress involved.

Using 5’ RNA-seq, we demonstrate that
iFhl1
was selectively upregulated by 10-fold in the left atrium by embryonic gestation day 17.5 (E17.5; p=2 x 10
-5
) but remained unchanged in the other cardiac chambers (see B). The preferential increase in expression in the left atrium was confirmed with X-gal staining of Fhl1
Lacz
mice hearts (see D, blue stain), and the selective expression of the induced isoform at the protein level was confirmed by Western blot (see C). Assessment of left atrial volume by magnetic resonance imaging in mice at 2 weeks of age showed that Fhl1-null mice have significantly larger left atria than wild-type littermates (0.63±0.10 μl vs. 0.45±0.04 μl, p=0.004).

The demonstrated selective upregulation of
iFhl1
prior to birth and the increase in left atrial volume that follows genetic ablation of
Fhl1
suggests that
Fhl1
is central in the heart’s ability to respond to physiological stress as represented by normal birth.
Abstract 314: Allogeneic Cortical Bone Stem Cells Preserve Cardiac Structure and Function by Inhibition of Cell Death and Enhancing Angiogenesis in the Swine Heart After Myocardial Infarction
Authors: Sharp Thomas E , Berretta Remus M , Starosta Timothy , Mohsin Sadia , George Jon C , Duran Jason M , Kubo Hajime , Houser Steven R
Published: July 2021

Introduction:
Novel therapies are needed to improve cardiac function after MI; one strategy is to replace lost myocardium. Despite the success of bone marrow- and cardiac- stem cell clinical trials, we’re still searching for the optimal stem cell type most suitable for cardiac regeneration. Previously, we described a novel cell population derived from the cortical bone (CBSCs) which repaired the heart post MI via transdifferentiation and paracrine signaling mechanisms in a mouse model. In the present study, we evaluate the translational potential of allogeneic CBSCs in swine MI model.

Hypothesis:
Intramyocardial injection of CBSCs into the MI border zone immediately after reperfusion will preserve cardiac structure and pump function by enhancing endogenous repair through secretion of paracrine factors.

Methods & Results:
Female Göttingen minipigs received MI via occlusion of the left anterior descending coronary artery (LAD) for 90 minutes, followed by reperfusion. Animals received either 20 million CBSCs (via 10 intramyocardial injections) or saline injections. Cardiac structure and function was evaluated using echocardiography at baseline and 4 weeks post-MI. During the 4 weeks after MI there was depression if pump function in saline treated group (EF: 69.27% ± 1.92 [baseline] to 46.305% ± 3.53 [4 weeks post MI]
p<0.0001
) and dilation of the LV (EDV: 39.01 ml ± 3.47 [baseline] to 51.5 ml ± 5.67 [4 weeks post MI] and ESV was 13.71 ml ± 2.47 to 27.72 ml ± 3.86 (
p= 0.0136
). The MI + CBSC group had no significant change in ventricular pump function from baseline to 4 weeks post-MI; while demonstrating preservation of cardiac structure indicating a decrease in ventricular remodeling/scar formation. A decrease in TUNEL+ cells and an increase in angiogenesis was also observed in CBSC’s treated animals.

Conclusion:
CBSC’s appear to reduce infarct expansion by reducing post MI myocyte death and by increasing angiogenesis. These data show that administration of CBSCs immediately after reperfusion of an infarcted region of the heart can reduce adverse cardiac remodeling and improve cardiac function.
Abstract 315: Stromal Cell-derived Factor 1 Protects From Diabetic Cardiomyopathy
Authors: Yan Xiaoqing , Wang Shudong , Chen Jing , Chen Jun , Zeng Jun , Tan Yi
Published: July 2021

We have demonstrated that stromal cell-derived factor 1(SDF-1) protects against palmitate-induced cardiac apoptosis, which is mediated by NOX-activated nitrosative damage and endoplasmic reticulum stress, via CXCR7, to activate AMPK/p38 MAPK-mediated IL-6 generation (Diabetes 62:2545-2558, 2013). Whether SDF-1 prevents diabetic cardiomyopathy has not been addressed. Here we evaluated the preventive effects of SDF-1 from diabetic cardiomyopathy in a high fat diet plus streptozotocin (HFD/STZ)-induced type 2 diabetic model in C57BL/6J mice. After 1 month on HFD, cardiac function was assayed by echocardiography, and then HFD-fed mice were injected with one low dose STZ (100mg/kg body weight, ip). Five days after STZ injection, mice with blood glucose levels ≥250 mg/dl were defined as diabetic. In parallel, the age-matched normal diet-fed mice injected with a same volume of citrate buffer (pH4.5) were used as control. After onset of diabetes, the mice were maintained on HFD or normal diet for another 4 months with or without SDF-1 treatment. Then cardiac function was assayed again, and the mice were sacrificed and cardiac tissue collected for cardiomyopathic index assay. We found that 1 month HFD feeding induced a significant insulin resistance without effect on cardiac function, but continued HFD feeding after STZ injection significantly impaired cardiac function, which were accompanied by increased insulin resistance and blood glucose, as well as blood insulin, triglyceride and cholesterol levels. Treatment with SDF-1 dose-dependently prevented diabetes-induced cardiac dysfunction but without significant effects on the above mentioned other pathophysiological parameters. These results indicate that SDF-1 possibly prevents diabetic cardiomyopathy via a direct cardiomyocyte action, which needs to be further defined in future study.
Abstract 325: miR-223 Negatively Regulate Ischemia/Reperfusion-induced Cardiac Necroptosis
Authors: Fan Guo-Chang , Qin Dongze , Wang Xiaohong , Yang Liwang , Huang Wei , Wang Yigang
Published: July 2021

It is well known that myocardial ischemia/reperfusion (I/R) causes myocyte apoptosis and necrosis. For many years, apoptosis was considered to be the only form of gene-regulated cell death, whereas necrosis was thought as a passive accidental cell death. Recent studies, however, clearly indicate that necrosis can be controlled by multiple genes, and RIPK1/3-regulated necrosis, called necroptosis, has gained well attention. We and others previously showed that miR-223, an anti-inflammatory miRNA, was greatly up-regulated in the infarcted heart. To test whether miR-223 regulates I/R-induced cardiac necroptosis, transgenic (TG) mice with cardiac-specific overexpression of miR-223 and miR-223 knockout (KO) mice were used and underwent global no-flow I/R (30min/1h). We observed that TG hearts displayed the better recovery of contractile function (+dP/dt: 92±4%), compared with wild-type (WT) hearts (65±3%). This improvement was accompanied with a 2.4-fold decrease in lactate dehydrogenase (LDH), a marker of necrosis, released from TG hearts, comparable to WTs. By contrast, KO-hearts showed the worse recovery of contractile function (+dP/dt: 41± 3%) than WTs (+dP/dt: 70±4%), and increased LDH release (3-fold). Notably, both TUNEL-staining and DNA fragmentation analysis for cardiac apoptosis showed no difference between groups. Western-blotting assays showed that protein levels of RIPK1, RIPK3 and MLKL, three known mediators in the necroptotic pathway, were reduced in TG hearts, whereas they were increased in KOs, compared to respective WT controls upon I/R. Furthermore, pre-injection of NEC-1s (1.65mg/kg), a specific inhibitor of necroptosis, into miR-223-KO mice, significantly improved cardiac function recovery during I/R, compared to saline-injected KOs. To elucidate the mechanisms underlying the miR-223-mediated cardiac necroptosis, we performed a series of experiments (bioinformatics, luciferase report assay, and western-blotting). Our results showed that miR-223 negatively regulated the expression of TNFR1 and death receptor 6 (DR6), two activators of the necroptotic pathway. Put together, this study indicates that miR-223 could control I/R-induced cardiac necroptosis via targeting the DR6/TNFR1-RIP1/3-MLKL pathway.
Abstract 331: Mir-433 Controls Cardiac Fibrosis
Authors: Tao Lichan , Wu Xiaoting , Chen Ping , Li Shanshan , Zhang Xiaomin , Bei Yihua , Xu Tianzhao , Xiao Junjie , Li Xinli
Published: July 2021

Background:
Cardiac fibrosis, a result of multiple injurious insults in heart, is a final common manifestation of chronic heart diseases and can lead to end-stage cardiac failure. MicroRNAs (miRNAs, miRs) participate in many essential biological processes and their dysfunction has been implicated in a variety of cardiovascular diseases including fibrosis. miR-433 has recently been implicated in renal fibrosis, however, its role in cardiac fibrosis is unclear.

Methods and results:
miR-433 was increased in heart samples from dilated cardiomyopathy patients as determined by qRT-PCRs. In addition, miR-433 was also consistently upregulated in mice model of cardiac fibrosis after myocardial infarction or heart failure. Additionally, miR-433 was found to be enriched in fibroblasts compared to cardiomyocytes. In neonatal cardiac fibroblasts, forced expression of miR-433 promoted cell proliferation as indicated by EdU and Ki-67 staining. Moreover, miR-433 overexpression promoted the transdifferentiation of fibroblasts into myofibroblasts as determined by qRT-PCR and western blot for α-SMA and collagen whether in the presence of TGF-β or not, indicating that miR-433 is sufficient to induce fibrosis. In addition, knockdown of miR-433 inhibited proliferation and the transdifferentiation into myofibroblasts, indicating that miR-433 is required for cardiac fibrosis. Interestingly, miR-433 did not affect the migration of cardiac fibroblast. Importantly, miR-433 antagomir could partially attenuate cardiac fibrosis induced by myocardial infarction in mice.

Conclusion:
both in vitro and in vivo. Inhibition of miR-433 represents a novel therapeutic strategy for cardiac fibrosis.
Abstract 347: Identification and Characterization of a miRNA Cohort Initiated Transitional Program That Controls Cell Cycle Arrest of the Perinatal Heart
Authors: Burgon Patrick G , Weldrick Jonathan J
Published: July 2021

During fetal and early perinatal development the myocardium undergoes a period of hyperplastic growth, which results in an exponential increase in the number of cardiomyocytes (CM) that will constitute the adult heart. Soon after birth, CMs proceed through a final round of cell division in the absence cytokinesis that results in binucleation of >95% of adult CMs. Fetal heart genes are re-activated with the onset of pathological hypertrophic or dilated cardiomyopathies, yet there is no evidence of CM re-entry into the cell cycle. Despite the importance of this phenomenon, little is known about the molecular basis for the transition from hyperplastic to hypertrophic-based myocardial growth.

Hypothesis: A perinatal heart gene program is necessary for the normal transition from a fetal heart gene program to an adult heart gene program.

To identify the molecular mechanisms and pathways involved in CM differentiation during the perinatal transition, RNA was isolated from E18, and 1, 3, 5, 7, 10 and 35d old mouse hearts. CM gene expression and micro-RNA profiles (n=3 arrays/time point) were determined by oligonucleotide array analysis. The raw array data was normalized by Robust Multi-array analysis. Empirical Bayes estimation of gene-specific variances was performed between each of the time points in order to identify genes that are transiently and significantly changed at days 3 and 5 as compare to E18 and 10d post-birth. The analysis identified 2,799 genes (E18 v 5d) and 3,347 genes (5d v 10d) that were then clustered to determine significant pathway enrichment (p<0.05) with Ingenuity Pathway Analysis.

Our analysis confirmed previous observations of a down regulation of glucose oxidative metabolism (p=0.02) with an up-regulation of fatty acid metabolism (p=0.0001) between E18 and 5d post-birth. Also, 63 cell cycle genes are collectively down regulated (p=4.3x10-4) between 5d and 10d post-birth. We identified 131 genes that are transiently up regulated at 5d compared to E18 and 10d and this transition was proceeded by a specific cohort of miRNAs. The data generated from this study provide new insight into the molecular mechanisms by which CMs regulate and permanently exit from the cell cycle.
Abstract 348: p38γ and δ Promote Heart Hypertrophy by Targeting the Mtor-inhibitory Protein Deptor for Degradation
Authors: González-Terán Bárbara , López Juan A , Rodríguez Elena , Leiva Luis , Martínez-Martínez Sara , Jiménez-Borreguero Luis J , Redondo Juan M , Vazquez Jesús , Sabio Guadalupe
Published: July 2021

Disrupted organ growth underlies the development of several diseases. Whereas the fetal heart grows mainly through proliferation, the postnatal heart grows through hypertrophy. Hypertrophy is also activated in the adult heart as a compensatory response to stress, but chronic ventricular hypertrophy leads to heart failure. The molecular mechanisms underlying ventricular hypertrophy are unknown. We show that cardiac expression and activation of p38γ and p38δ increases during postnatal development and these kinases are activated by the hypertrophy-inducing stress stimuli angiotensin II and phenylephrine. p38γ and p38δ promote cardiac hypertrophy by phosphorylating the mTORC1 and mTORC2 inhibitor DEPTOR, promoting its degradation and thereby activating mTORC1 and mTORC2. Hearts from mice lacking one or both kinases were below-normal size, had high levels of DEPTOR and consequently low activity of the mTOR pathway, and reduced protein synthesis. The mTOR inhibitor, rapamycin, equalized heart weight in wild-type and p38γ/δ-/- mice. Moreover, p38γ/δ-/- mice were protected against pathological ventricular hypertrophy, establishing p38γ/δ as key regulators of this process.
Abstract 350: Atorvastatin Attenuates Pressure Overload-induced Cardiac Hypertrophy and Dysfunction Through Enhanced Autophagy
Authors: Zhao Zhuo , Wang Wei , Wang Hua-Ting , Geng Qing-Xin , Zhao Di , Su Guohai
Published: July 2021

Aims:
Cardiac hypertrophy is a maladaptive change in response to pressure overload and is also an important risk for developing heart failure. We previously demonstrated that atorvastatin inhibits cardiac hypertrophy and remodeling in a mouse model of transverse aorta constriction (TAC). This study was designed to determine the regulation of atorvastatin on cardiac autophagy and its association with the development of cardiac hypertrophy and dysfunction in the mice TAC model.

Methods and results:
TAC or sham operations were performed in male C57/L6 mice at 8 weeks of age. Atorvastatin (50 mg/kg/day) or vehicle (normal saline) were administered daily by oral gavage to TAC mice (n=10 per group). Echocardiography and real-time PCR data showed that chronic atorvastatin treatment for four weeks significantly attenuated pressure overload-induced cardiac hypertrophy and dysfunction, as well as cardiac mRNA level of atrial natriuretic factor (ANF), a biomarker of cardiac hypertrophy and heart failure. After 4 weeks of TAC, results from electron microscopy and Western blot showed that cardiac autophagy was activated, evidenced by the increased expression of microtubule-associated protein-1 light chain 3-II (LC3-II), Beclin-1, caspase-3, and the formation of autophagosomes. Interestingly, cardiac autophagy was further increased by the treatment of atorvastatin for 4 weeks. Western blot analysis showed phosphorylated Akt and mammalian target of rapamycin (p-mTor) decreased in the heart of TAC versus sham mice, which were further decreased by atorvastatin treatment.

Conclusions:
These findings suggest that atorvastatin attenuates cardiac hypertrophy and dysfunction in TAC mice probably through its regulation on cardiac autophagy via Akt/mTor pathways.
Abstract 351: Late-life Activation of GPR30 by G1 Reverses Diastolic Dysfunction in Senescent Fischer344 x Brown Norway Female Rats
Authors: Alencar Allan , Wang Hao , de Silva Jaqueline , Lin Marina , Sun Xuming , Groban Leanne
Published: July 2021

Introduction:
The aged heart is characterized by impaired lusitropy and increased stiffness, and no proven pharmacologic interventions exist that limit these manifestations of left ventricular diastolic dysfunction (LVDD). G1, a selective agonist to the estrogen receptor GPR30, attenuated the effects of estrogen (E2) loss on LVDD in a hypertensive model. To extend prior studies, we determined the cardioprotective potential of chronic GPR30 activation in the female Fischer344 x Brown Norway (F344BN) rat, a normotensive aging model.

Methods and Results:
Bilateral oophorectomy (OVX) or sham-operations were performed in middle- (Mid) (18 months) and Old-aged rats (27 months). At 28 months of age, Old rats were randomized to daily G1 (100 μg/kg/day, s.c.) or vehicle (VEH; soybean oil) injections (n=7 rats/group). Following 8 weeks of treatment, left ventricle (LV) mass was greater in Old vs. Mid-aged rats, independent of E2 or G1, while systolic function and LV wall thicknesses were similar among groups. Myocardial relaxation (e’) was reduced (P<0.001) and LV filling pressure (E/e’) was increased (P<0.01) in Old vs. Mid-aged rats, and this was exacerbated by OVX (P<0.01) and reversed by late-life G1 treatment. Systolic blood pressure (SBP) increased by 20% after mid-life OVX, whereas late-life E2 loss had no effect on SBP, irrespective of G1. Cardiac chymase expression was increased in E2 deficient hearts determined by Western blot and G1 modestly limited this E2/age effect.

Conclusion:
Our data indicate that late-life G1 treatment reverses the detrimental effects of advanced age and E2 deficiency on diastolic function, possibly via interactions with the noncanonical cardiac renin angiotensin system.
Abstract 355: Exercise Prevents Doxorubicin-induced Cardiotoxicity via Targeting Microrna-669a-5p in Mice
Authors: Bei Yihua , Xu Jiahong , Xu Tianzhao , Chen Ping , Che Lin , Xiao Junjie
Published: July 2021

Doxorubicin (Dox)-induced cardiotoxicity, usually associated with increased oxidative stress, myofibrillar deterioration, and impaired cardiac contractile function, is a serious complication of antitumor therapy which may not be detected for many years. Growing evidence indicates that the regulation of cardiac microRNA (miRNA, miR) in response to exercise is essentially involved in the protective effect of exercise in the treatment of cardiovascular diseases. However, it is largely unknown whether and how exercise could prevent Dox-induced cardiotoxicity via regulating miRNA biology. In the current study, C57BL/6 mice were either subjected to a 3-week swimming program or remained sedentary. Mice were then treated with Dox (ip. 4 mg/kg/week for 4 weeks) to induce cardiotoxicity. Our data demonstrated that Dox resulted in marked reduction of cardiac ejection fraction (EF, %) and fractional shortening (FS, %) as measured by echocardiography. Interestingly, exercise significantly improved cardiac EF (%) and FS (%) in Dox-treated mice, indicating the protective effect of exercise in Dox-induced cardiotoxicity. Then, we performed microarray analysis (Affymetrix 3.0) showing that miR-27a-5p, miR-34b-3p, miR-185-3p, miR-203-3p, miR-669a-5p, miR-872-3p, and let-7i-3p were significantly reduced, while miR-2137 was increased in the hearts of exercised Dox-treated mice versus sedentary Dox-treated mice (FC(abs)>1.5, p<0.05). Using qRT-PCR, we further verified that miR-669a-5p was reduced by exercise training in Dox-treated mice. These data reveal that miR-669a-5p might be a potential miRNA mimicking the benefit of exercise in Dox-induced cardiotoxicity. Further study is needed to clarify the functional effect of miR-669a-5p and to identify its downstream target gene that contributes to the prevention and treatment of Dox-induced cardiotoxicity.
Abstract 365: Domain-specific Roles for GRK2 in Cardiac Hypertrophy and Heart Failure
Authors: Schumacher Sarah M , Gao Erhe , Chuprun J. Kurt , Koch Walter J
Published: July 2021

During heart failure (HF), cardiac levels and activity of the G protein-coupled receptor (GPCR) kinase (GRK) GRK2 are elevated and contribute to adverse remodeling and contractile dysfunction, while inhibition via a carboxyl-terminal peptide, βARKct, enhances heart function and can prevent HF development. Mounting evidence supports the idea of a dynamic “interactome” in which GRK2 can uncouple GPCRs via novel protein-protein interactions. Several GRK2 interacting partners are important for adaptive and maladaptive myocyte growth; therefore, an understanding of domain-specific interactions with signaling and regulatory molecules could lead to novel targets for HF therapy. For instance, GRK2 contains a putative amino-terminal Regulator of G protein Signaling (RGS) domain (βARK-RGS) that directly interacts with Gq and appears to inhibit signaling without altering Gq enzymatic activity. Previously, our lab investigated cardiac-specific transgenic (Tg) expression of a fragment of this RGS domain (βARKnt). This fragment did not alter acute hypertrophy after pressure overload or demonstrate RGS activity in vivo against Gq-mediated signaling. In contrast, βARKnt induced hypertrophy and elevated β-adrenergic receptor (βAR) density without altering agonist-induced contractility or adenylyl cyclase activity, due to a compensatory increase in GRK2 activity. Importantly, though, βAR downregulation in response to chronic agonist administration was attenuated by βARKnt expression, indicating a novel regulation of βAR receptor density. Given these findings we have recently investigated the effect of βARKnt expression during chronic pressure overload post trans-aortic constriction (TAC). Echocardiographic analysis revealed increased posterior wall thickness and left-ventricular mass 4 weeks post-TAC compared to non-transgenic littermate controls (NLC). Importantly, despite enhanced hypertrophy, the progression to HF was inhibited in βARKnt mice 14 weeks post-TAC (%LV Ejection Fraction of 36.1 ± 0.2 in NLC versus 56.6 ± 0.9 in Tg mice). While mechanistic characterization is underway, these data indicate that βARKnt-mediated regulation of βAR density may provide a novel means of cardioprotection during pressure-overload induced HF.
Abstract 372: Regulation of Ski and Scleraxis in the Infarcted Rat Heart
Authors: Filomeno Krista L , Rattan Sunil G , Bage Sheri , Zeglinski Matthew , Czubryt Michael P , Dixon Ian M
Published: July 2021

Introduction:
Coronary heart disease is causal to myocardial infarction (MI) and cardiac fibrosis. Upon ischemic myocardial injury, resident cardiac fibroblasts phenoconvert to myofibroblasts and synthesize large amounts of fibrillar collagens to produce scar tissue. Although the myofibroblast numbers are reduced in the infarct scar following the completion of wound healing, a sub-population of cells persist in the wounded area, leading to maladaptive chronic remodeling of the scar area and eventually the non-infarcted myocardium. Ski has been identified as a repressor of the TGF-β1 signaling pathway, attenuating the myofibroblast phenotype and its functional properties. Scleraxis has been implicated in canonical TGF-β1 signaling to promote collagen1α2 expression. We investigated how Ski and Scleraxis contribute to physiological and pathological wound healing in vivo.

Methods:
The study was carried out using 64 male Sprague-Dawley rats. The left anterior descending (LAD) coronary artery was ligated to induce a myocardial infarction. Control (sham) operated animals underwent surgery without ligation of the LAD artery. Animals were sacrificed at 2, 4, and 8 weeks post-MI and tissue collected for Western blot and qPCR studies.

Results:
Scleraxis mRNA expression remained at baseline at 2 and 8 weeks post-MI, but was significantly increased 4 weeks post-MI. Scleraxis protein expression was down-regulated within the scar area of infarcted hearts when compared to control samples 2 and 4 weeks post-MI. Ski mRNA expression was up-regulated within the scar area of infarcted hearts 2, 4 and 8 weeks after infarction.

Conclusions:
Scleraxis protein is down-regulated in myofibroblasts of the infarct scar in the chronic stages of myocardial infarction, corresponding to the maturation of the scar. At these stages of wound healing, we have previously published that Ski is up-regulated in the cytosol of these same cells. We suggest reciprocal feedback in the expression of these two proteins exists in myofibroblasts in the infarct scar. We hope to learn more about the Ski/Scleraxis feedback loop in pathological wound healing to identify novel therapeutic targets.
Abstract 376: Amino Terminal C0-C1f Region of Cardiac Myosin Binding Protein-C is Essential for Normal Cardiac Function
Authors: Lynch Thomas L , Kuster Diederik W , Barefield David , Sivaguru Mayandi , Previs Michael J , Lee Kyounghwan , Govindan Suresh , Craig Roger , Warshaw David M , Sadayappan Sakthivel
Published: July 2021

Rationale:
Cardiac myosin binding protein-C (cMyBP-C) is a trans-filament protein that has been shown to regulate cardiac function via its amino terminal (N’) regions. However, it is unknown whether the first 271 residues (C0-C1f region) are necessary to regulate contractile function in vivo.

Hypothesis:
The N’-region of cMyBP-C is critical for proper cardiac function in vivo.

Methods and Results:
Transgenic mice with approximately 80% expression of mutant truncated cMyBP-C missing C0-C1f (cMyBP-C
110kDa
), compared to endogenous cMyBP-C, were generated and characterized at 3-months of age. cMyBP-C
110kDa
hearts had significantly elevated heart weight/body weight ratio, fibrosis, nuclear area and collagen content compared to hearts from non-transgenic (NTG) littermates. Electron microscopic analysis revealed normal sarcomere structure in cMyBP-C
110kDa
hearts but with apparently weaker cMyBP-C stripes. Furthermore, the ability of cMyBP-C to slow actin-filament sliding within the C-zone of native thick filaments isolated from NTG hearts was lost on thick filaments from cMyBP-C
110kDa
hearts. Short axis M-mode echocardiography revealed a significant increase in left ventricular (LV) internal diameter during diastole in cMyBP-C
110kDa
hearts. Importantly, cMyBP-C
110kDa
hearts displayed a significant reduction in fractional shortening compared to hearts from NTG littermates. We further observed a decrease in the thickness of the LV interventricular septum and free wall during systole in cMyBP-C
110kDa
hearts. Strain analysis using images acquired from ECG-Gated Kilohertz Visualization identified a significant deficit in global longitudinal strain in cMyBP-C
110kDa
hearts compared to NTG hearts.

Conclusion:
The N’-region of cMyBP-C is indispensable for maintaining normal cardiac morphology and function and loss of this region promotes contractile dysfunction both at the molecular and tissue levels.
Abstract 386: The Role of GAPDH in the Cardio-metabolic Response to Ischemia
Authors: Rhee James , Houstis Nicholas , Asara John , Liu Laura , Jang Cholsoon , Arany Zoltan , Rosenzweig Anthony
Published: July 2021

Fundamental changes in nutrient metabolism underlie many disease processes, including obesity, diabetes, and cancer. Metabolic derangements are also a hallmark of heart disease, both in the context of failure and ischemia, and likely contributors to its etiology. For example, while the healthy heart favors fats as a fuel, failing hearts will consume more glucose; but it is unclear if this is pathological or protective. It is very likely that manipulation of metabolic pathways can affect, and possibly augment and protect, heart function. Yet no drug therapy exists that targets cardiac metabolism. Staples of ischemic disease management largely focus on anti-platelet, cholesterol-lowering, and beta-adrenergic blocking regimens. Heart failure medicines focus on maladaptive neuro-hormonal responses, a strategy several decades old. Our goal here is to delineate exactly how critical aspects of metabolism are altered in cardiac ischemia, and to identify new targets of pharmacological intervention.

Metabolism largely remains unexplored because of its intricate network of regulation, compounded by the fact that variations in this network will often escape traditional methods of gene expression profiling. But by using high throughput metabolomic and proteomic platforms, we have striking evidence that the glycolytic enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is instrumental in the heart’s response to ischemia. Dynamic, real-time metabolomic flux using heavy carbon isotope labeling points toward a partial shift of glycolytic intermediates toward lipid synthesis during ischemic stress in cardiomyocytes, precisely at the step catalyzed by GAPDH. Expansive phospho-proteomic analyses from Langendorff ex vivo hanging heart experiments show that this shift in metabolism may be triggered by an inhibitory phosphorylation of GAPDH. Our hypothesis that glycolysis is in part rerouted toward triglyceride synthesis is a revolutionary departure from decades-old perceptions of energy management. Modulating GAPDH function, either directly or indirectly via partner proteins, may offer insight into untapped areas of therapy. Our early attempts with chemicals that inhibit GAPDH already show heart cells with improved survival under ischemia.
Abstract 403: Mitochondrial Complex II is a Source of the Reserve Respiratory Capacity that is Regulated by Metabolic Sensors via Sirtuin 3
Authors: Pfleger Jessica , He Minzhen , Abdellatif Maha
Published: July 2021

A cell’s survivability depends on its ability to meet its energy requirements. We hypothesized that the cells’ mitochondrial reserve respiratory capacity (RRC) is a critical component of its bioenergetics that can be utilized during an increase in energy demand, thereby, enhancing viability. Our goal was to identify the elements that regulate and contribute to the development of RRC and its involvement in cell survival. Our results show that development of RRC is dependent on metabolic substrate availability in a cell type-dependent manner. While the neonatal rat cardiac myocytes (NRCM) utilize glucose as the main substrate, developing a RRC [1.4-2.5 fold higher than basal oxygen consumption rate (OCR)] required fatty acids in addition to glucose. Accordingly, inhibition of either glucose or fatty acid oxidation separately, completely abrogated RRC, while having little impact on basal OCR, which is sustainable with either substrate or glutamate in the medium. Conversely, RRC was enhanced (1.4-1.8 fold) through increasing glucose oxidation via inhibiting pyruvate dehydrogenase kinase with dichloroacetate, or through increasing fatty acid oxidation via activation of AMP-activated kinase (AMPK). The latter was partly mediated through peroxisome proliferator-activated receptor alpha. These results suggested that RRC is an independently regulated entity of the cells’ bioenergetics. An electron flow activity assay revealed that the increase in RRC correlated with a specific increase in complex II (cII) activity. Inhibiting or disassembling holo cII completely abolished RRC, accompanied by a slight decrease in basal OCR (0.82-0.9 fold), thus confirming it as the source of RRC. Moreover, the development of RRC required Sirtuin (Sirt)3. Functionally, we show that enhancing RRC via fatty acid oxidation with 5-Aminoimidazole-4-carboxamide 1-β-Dribofuranoside in NRCM results in a burst of cII-dependent oxidative phosphorylation accompanied by reduced superoxide production and enhanced cell survival post-energy deprivation conditions. Thus, for the first time, we show that metabolic sensors increase the cells’ RRC via activating cII in a Sirt3-dependent manner, and that this mechanism can be exploited for increasing cell survival after hypoxia.
Abstract 419: Stim1 is Associated With Calcium Microdomains That are Required for Myofilament Remodeling and Signaling During Cardiac Hypertrophy
Authors: Parks Cory , Sullivan Ryan D , Mancarella Salvatore
Published: July 2021

Stromal Interaction Protein 1 (STIM1) is the intracellular component of the store operated calcium channels. It is a ubiquitous Ca2+ sensor, prevalently located in the sarcoplasmic reticulum. In non-excitable cells, STIM1 is a key element in the generation of Ca2+signals that lead to gene expression and cell proliferation. A growing body of literature now suggests that STIM1 is important for normal heart function and plays a key role in the development of pathological cardiac hypertrophy. However, the precise mechanisms involving STIM1 and the Ca2+ signaling in excitable cells are not clearly established. We show that in neonatal rat cardiomyocytes, the spatial properties of STIM1-dependent Ca2+ signals determine restricted Ca2+ microdomains that regulate myofilaments remodeling and spatially segregated activation of pro-hypertrophic factors. Indeed, in vivo data obtained from an inducible cardiac restricted STIM1 knockout mouse, exhibited left ventricular dilatation associated with reduced cardiac contractility, which was corroborated by impaired single cell contractility. Furthermore, mice lacking STIM1 showed less adverse structural remodeling in response to pathological pressure overload-induced cardiac hypertrophy (transverse aortic constriction, TAC). We further show that the Ca2+ pool associated with STIM1 is the ON switch for extracellular signal-regulated kinase (ERK1/2)-mediated cytoplasm to nucleus signaling. These results highlight how STIM1-dependent Ca2+ microdomains have a major impact on intracellular Ca2+ homeostasis, cytoskeletal remodeling, signaling and cardiac function, even when excitation-contraction coupling is present.
Abstract 42: Differentiation of Human Multipotent Vascular Stem Cells Contributes to Vascular Diseases
Authors: Huang Wen-Chin , Wang Aijun , Li Song
Published: July 2021

Vascular disease, such as neointimal hyperplasia and atherosclerosis, involves in migration and proliferation of vascular cells in blood vessel wall. It is generally accepted that the de-differentiation of vascular smooth muscle cells (SMCs) contributes to vascular diseases. However, previous studies suggest that resident multipotent vascular stem cells (MVSCs) are also involved in neointima formation. In this study, we isolated MVSCs from the medial layer of human carotid artery and thoracic aorta by explant cultures, characterized these cells, and identified the origin of these vascular cells populated in lesion areas. Human MVSCs could be isolated from healthy and diseased blood vessels, were cloneable, and were positive for stem cell markers SOX10 and SOX17 but not SMC markers α-actin and calponin-1. MVSCs were able to differentiate into neural cells, SMCs and other mesenchymal lineages in vitro. In addition, we examined the location of MVSCs in diseased vascular wall by immunohistochemistry. The majority of cells within tunica media were calponin-positive cells, whereas a small population of cells was proliferative and double positive for SOX10 and Ki67 in the border between tunica intima and media. The number of SOX10+ cells in atherosclerotic lesions was more than that in healthy blood vessels, and some of these cells were double positive for SOX10 and chondrogenic markers. Furthermore, we performed in situ PCR and proximity ligation assays to stain for the epigenetic markers of SMC lineage. The results suggested that SOX10+ cells in cell cultures and tissue sections were not derived from de-differentiated SMCs. In conclusion, these findings support that MVSCs contributes to human vascular diseases.
Abstract 61: miRNA-21 Targets Left Ventricular Peroxisome Proliferator-activated Receptor Alpha in a Rat Model of Type 4 Cardiorenal Syndrome
Authors: Kriegel Alison J , Liang Mingyu , Liu Yong , Liu Pengyuan , Cowley Allen W , Casati Marc C , Chuppa Sandra
Published: July 2021

Type 4 cardiorenal syndrome (CRS4) is a condition in which chronic kidney disease (CKD) contributes to cardiovascular pathology including cardiac dysfunction, left ventricular (LV) hypertrophy, atherosclerosis, and heart failure. We have used a rat model of CKD, the 5/6 nephrectomy (5/6 NX), to study molecular mechanisms that mediate the development of cardiac pathology in CRS4. We previously reported that the upregulation of microRNA miR-21-5p (miR-21) in the left ventricle (LV) was accompanied by pathological remodeling and a drop in fractional shortening in adult male Sprague Dawley rats 7 weeks after 5/6 NX. Systemic knockdown of miR-21 in 5/6 NX rats with LNA-modified anti-miR-21 improved cardiac function, however it did not reduce the modest fibrosis observed with our 5/6 NX model or upregulate miR-21 targets identified in other models of cardiac pathology, suggesting a novel cardiac target for miR-21 in this model. Through next-generation mRNA sequencing of LV tissues from anti-miR-21 treated rats, and subsequent Ingenuity Pathway Analysis, we have found cardioprotective alterations in genes related to cardiac hypertrophy, metabolism, immune and inflammatory signaling, and atherosclerosis. Suppression or reduction of miR-21 target peroxisome proliferator-activated receptor alpha (PPARa), a master regulator of fatty acid oxidation, has been reported to be involved in all of these processes. Translational suppression of PPARa through miR-21 has been confirmed in other tissues, but not in the myocardium. The average LV PPARa protein expression level was significantly reduced (-37.7 ± 5.4%) in the 5/6 NX model and restored by miR-21 knockdown (Western blot; n=5-6/group; mean ± SEM). Immunohistochemistry revealed that the pronounced alterations in PPARa expression occurred within cardiomyocytes (CMs) in these samples. Transfection of neonatal CMs with pre-miR-21, significantly reduced PPARa protein expression within 48 hours (-23.0 ± 0.9%; n=3/group). These data indicate that PPARa suppression by miR-21 occurs within LV in 5/6 NX model of CKD and that miR-21 can regulate PPARa in CMs. This regulation may be relevant in other models of chronic cardiac disease where increased miR-21 and suppression of PPARa have been independently reported.