bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deficiency of Prostaglandin E2 Receptor Subtype 4 Causes Dysregulation of Cholesterol Homeostasis in Mice
Authors: YING FAN , CAI Yin , TANG Eva HoiChing 
Published: November 2023

Mice lacking prostaglandin E2 receptor subtype 4 (EP4), one of the four receptors identified for prostaglandin E2 developed spontaneous hypercholesterolemia. The present study investigated the cause of the elevated plasma cholesterol in EP4 knockout mice. 12–15 weeks old normal diet fed EP4 knockout mice show a 48% increase in total cholesterol as compared to their wildtype littermates. The proportion of plasma cholesterol present in very low density lipoprotein (VLDL)/low density lipoprotein (LDL) increased by 84% and that in high density lipoprotein (HDL) increased by 15.6%. The increase in plasma cholesterol was independent of changes in intestinal cholesterol absorption, as there were no changes in fecal neutral sterol excretion and in intestinal ATP‐binding cassette (ABC) A1 and G5 protein expression between EP4 wildtype and knockout mice, while hepatic ABCA1 was significantly increased in the latter – suggesting that the deficiency of EP4 increases cholesterol efflux from the liver. The absence of EP4 reduced phosphorylation of 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase (HMG‐CoA reductase) and in so doing increased HMG‐CoA reductase activity, the rate‐limiting enzyme for cholesterol synthesis. Furthermore, deficiency of EP4 reduced hepatic mRNA (by 23%) and protein expression (by 36.7%) of low density lipoprotein receptor (LDLR), suggesting that there is impaired cholesterol clearance by the liver. Such conclusion was further reinforced by studies where EP4 knockdown in human hepatoma cell lines reduced cell surface LDLR protein, impaired LDL uptake and reduced intracellular cholesterol. Lastly, EP4 deficiency decreased the catabolism of cholesterol to bile acids. Cholesterol 7α‐hydroxylase (CYP7A1) is the rate‐limiting step in the classic pathway of bile acid biosynthesis, and its mRNA expression levels were decreased by 57.8% in livers of EP4 deficient mice as compared to those in wildtype mice. While, the expression of sterol 27‐hydroxylase (CYP27A1) which initiates the alternate or acidic pathway of bile acid biosynthesis was unchanged. Indeed, EP4 knockout mice exhibited higher plasma but lowered hepatic levels of total bile acids. In summary, the present study shows that the hypercholesterolemia in EP4 deficient mice is mediated by multiple mechanisms including increased hepatic cholesterol biosynthesis, increased cholesterol efflux from the liver, impaired cholesterol clearance by the liver, reduced conversion and/or elimination of cholesterol into bile acids. The lack of EP4 in mice leads to an incapacity to maintain normal plasma cholesterol levels, suggesting a loss of coordinate regulation for cholesterol homeostasis, identifying a new metabolic dimension in the physiological role played by endogenous EP4.Support or Funding InformationThis work is supported by The Research Grant Council Early Career Scheme (ECS) Project code: 27101314.
Activation of TGF‐β/Smad signaling pathway by high cholesterol diet: possible inhibition by rutin compound
Authors: Alrejaie Salim S. , AlSharari Shakir , Hafez M. 
Published: November 2023

BackgroundHigh‐cholesterol diet (HCD) increases the oxidative stress in liver resulting in generation of reactive oxygen species (ROS). ROS may activate transforming growth factor beta (TGF‐β) and Mothers Against decapentaplegic Homolog (Smad)signaling pathway leading to hepatotoxicity. Rutin is a natural flavonoid (vitamin p), which possesses an antioxidant activity with protective potential. The aim of the present study was to investigate the potential alleviating effects of rutin against hyper‐cholesterolemia‐induced TGF‐β/Smad signaling pathway activation and hepatotoxicity in rat.MethodsMale Wistar rats were divided into four groups: G‐I control (Rat chow), G‐II Rutin (0.2% in rat chow), G‐III HCD (1% cholesterol and 0.5% cholic acid in rat chow) and G‐IV rutin (0.2%) + HCD. Animals received freshly prepared experimental diets for 6 consecutive weeks. In hepatic tissue, gene expressions of TGF‐β, Smad‐2 and Smad‐4 were measured using real time PCR.ResultsIn HCD group, the gene expression levels of TGF‐β, Smad2 and Smad4 significantly increased by8‐, 8.5‐ and 5.3‐folds expressions, compared to the control group. On the other hand, administration of rutin in combination with HCD induced a significant repair of the HCD‐induced alteration in the gene expression of TGF‐β, Smad2 and Smad4 compared to the HCD group expression levels.ConclusionOur findings revealed that TGF‐β/Smad signaling pathway is involved in the hepatotoxicity induced by HCD and rutin inhibits hepatotoxicity via suppressing this pathway. Therefore, rutin might be considered as a protective agent for hepatotoxicity.Support or Funding InformationThe authors extend their appreciation to the Deanship of Scientific Research at King Saud University for funding this work through research project no NFG‐14‐02‐13
The Integration of Mechanobiology and Biomechanics at Primary Cilia
Authors: Jacobs Christopher Rae , Nguyen An 
Published: November 2023

Cellular mechanosensation is critical in diseases responsible for enormous human suffering including atherosclerosis, osteoarthritis, cancer, and osteoporosis. Nonetheless, very little is understood about the molecular mechanisms of mechanotransduction outside of a small number of specialized sensory cells. Primary cilia are solitary linear cellular extensions that extend from the surface of virtually all cells. For decades, the biologic function of these enigmatic structures was elusive, however, recent evidence suggests an emerging picture in which the primary cilium functions as a complex nexus where both physical and chemical extracellular signals are sensed and responses coordinated.In our laboratory we have shown that primary cilia act as mechanical sensors in bone and that conditional deletion of primary cilia lead to mechanosensing defects. Recently, we developed a novel combined experimental/modeling approach to determine the mechanical properties of primary cilia. We found a wide variety of previously unreported deformation modes including smooth bending and rigid‐body rotations. This suggests that the mechanics of both the cilium shaft and basal anchorage are important to understanding deflection patterns. Interestingly, both the cilium itself and its anchorage to the microtubule cytoskeleton alter their structure in response to physical loading, suggesting structural adaptation or “remodeling”. We have also developed novel molecular biology tools to elucidate the details of mechanically activated ciliary signaling pathways. For example, we have created a cilia‐directed biosensor that has allowed us to distinguish intraciliary from intracellular calcium signaling. We have also developed a method for distinguishing the roles of the cytoplasmic and ciliary pools of proteins that are found in both compartments. In summary, primary cilia are non‐linear, richly varied, mechanical structures (biomechanics) as well as structurally adaptive (mechanobiology). Simultaneously they are a biochemical microdomain where signaling events are catalyzed, enhanced, and integrated.Support or Funding InformationSupported by NIH AR45989 and AR54156 and New York State Stem Cell Grant N089‐210
Caspase‐1 P20 Fragment, a Marker for Inflammasome Activation, is Elevated in Serum of Patients during Myocardial Infarction
Authors: Morgan Andrew , Liang Bruce , Chen Kai , Na Doohwan , Gold Courtney , Azrin Michael , Lee JuYong , Schumacher Jayne , Yue Lixia , Aguila Hector Leonardo , Shapiro Linda , Tate Janet , Protas Matthew 
Published: November 2023

AimsIncreased inflammation contributes to the development of myocardial infarction (MI) and impacts adversely infarct healing. Caspase‐1 is an end effector of inflammasome activation and is an important mediator of systemic inflammation. Caspase‐1 is cleaved to produce a 20 kDa peptide upon activation. We tested the hypothesis that the 20kDA peptide is elevated in patients during and after acute myocardial infarction.Methods and ResultsBetween 12/10/2007 and 8/10/2015 complete data for caspase‐1, troponin, CK, and CKMB during the acute event and the post‐MI period were obtained in 75 consecutive subjects with type 1 acute myocardial infarction. The average age was 61.8±14 years. Using a solid phase enzyme‐linked immunosorbent assay, the 20 kDa peptide was detected in serum during ST elevation and non‐ST elevation MI and its peak level(166.2±11.2 pg/mL) was higher than the non‐peak level(96.3±6.2 pm/mL, p=<0.0001) during the acute phase. The peak level was higher than the level after the acute MI (termed post‐MI, 115.4±8.5 pg/mL, p=<0.0001), and both levels were higher than that of healthy subjects (79.19±5.3 pg/mL). The peak level was not correlated with peak cardiac cTnI or peak CK‐MB.ConclusionsActivated caspase‐1 20 kDa peptide rises and falls during acute MI. The post‐MI level remains elevated and may represent persistent inflammation. The data provided evidence for inflammasome activation during acute MI in humans. The elevated circulating 20 kDa peptide may have implications as biomarker for cardiac injury and healing.
mTORC1 Signaling Mediates Cytoprotective Effects of H2S in Cerebral Circulation
Authors: Liu Jianxiong Dianna , Basuroy Shyamali , Leffler Charles W , Parfenova Helena 
Published: November 2023

Cortical astrocytes are key functional components of the neurovascular unit. Our previous study in newborn pigs has demonstrated that astrocyte functions in cerebral blood flow regulation are extensively impaired following neonatal seizures. A cytoprotective gaseous mediator, H2S, enzymatically produced by cortical astrocytes or released by a donor compound, NaHS, prevents deleterious effects of seizures on astrocyte‐mediated cerebral vascular functions. However, the mechanism of H2S cerebroprotection remains elusive. Serine/threonine protein kinase mTOR is a critical component of the cell survival mechanism during stress conditions. Our novel finding suggests that rapamycin‐sensitive mTOR complex 1 (mTORC1) is highly expressed in cortical astrocytes from newborn pigs. We tested the hypothesis that mTORC1 is a key signaling component in H2S‐mediated astrocyte protection against cerebral vascular stress caused by neonatal seizures. The role of mTORC1 in the newborn pig cerebral circulation was tested using rapamycin (0.5 mg/kg ip). Rapamycin reduced mTOR phosphorylation at Ser2448 in cortical astrocytes, indicating effective inhibition of astrocytic mTOR activity. In control intact pigs, rapamycin had no effects on systemic (mean arterial blood pressure, heart rate, core body temperature) or cerebral vascular parameters (diameter of pial arterioles, the major resistance vessels in the brain). Epileptic seizures were induced by bicuculline (3 mg/kg ip) in control saline‐treated piglets or in piglets pretreated with NaHS (3 mg/kg ip), without or with co‐administered rapamycin. Astrocyte‐mediated cerebral vascular functions were tested during delayed postictal period (48 h after seizures) by responses of pial arterioles to astrocyte‐dependent vasodilators (ADP, glutamate, and ionotropic glutamate receptor agonist quisqualate) by live microscopy using the cranial window technique. In control postictal pigs, all astrocyte‐dependent pial arteriolar responses were greatly reduced, whereas the astrocyte‐independent vascular smooth muscle responses (isoproterenol, sodium nitroprusside) remained intact. Systemically administered NaHS had remarkably strong cerebroprotective effects and completely prevented the loss of astrocyte‐dependent vascular responses in postictal pigs. In contrast, in piglets with rapamycin‐inhibited mTORC1 activity, NaHS failed to rescue the neonatal brain from the seizure‐induced loss of astrocyte‐dependent cerebral vascular responses. We conclude that mTORC1 signaling mediates the protective effects of H2S in the cerebral circulation and is critical in preventing the loss of astrocyte functions in cerebral blood flow regulation caused by neonatal seizures.Support or Funding InformationThe study was supported by NIH/NHLBI/NINDS.
Doxorubicin‐Induced Chronic Upregulation of Transforming Growth Factor‐beta
Authors: Mancilla Trevi Ann , Andrews Thomas , Aune Gregory 
Published: November 2023

As a result of their treatment, childhood cancer survivors face an increased risk of acute and chronic heart failure. Epidemiological studies have shown the anticancer drug doxorubicin, while effective, to be cardiotoxic. Patients suffering from chronic doxorubicin cardiotoxicity exhibit interstitial fibrosis, one component of heart failure. This project aims to elucidate the mechanism of fibrosis in doxorubicin‐induced heart failure by examining changes in the transforming growth factor‐beta (TGF‐β) signaling pathway after exposure to doxorubicin.Our novel model involves treating 2 week old C57BL/6J mice with five weekly intraperitoneal injections of 3 mg/kg of doxorubicin. Cardiac tissue was collected one week after the final injection and at 80 weeks of age to assess early and long‐term recovery points. Data previously gathered by our lab show increased interstitial fibrosis in doxorubicin‐treated animals, even after exposure ceases. In vitro studies show a direct effect of doxorubicin on cardiac fibroblasts, inducing collagen production at the transcriptional level.Left ventricular TGF‐β levels increased in an age‐dependent and treatment‐dependent manner, as shown by immunohistochemistry. Cells positively‐stained for TGF‐β were more abundant in doxorubicin‐treated animals at the 7 week and 80 week time points compared to control mice (p=0.03 and p<0.001, respectively). Additionally, positively stained cells were located in the interstitium, indicating that the positive cells were cardiac fibroblasts. Preliminary data indicates an increase in matrix metalloproteinase‐2 (MMP‐2) in the 7 week doxorubicin‐treated mice. As a mediator of collagen degradation, MMP‐2 is an indicator of cardiac remodeling.Doxorubicin treatment causes sustained molecular changes evidenced by the short‐term and long‐term increases in the signaling cytokine TGF‐β in the murine left ventricle. Early changes in collagen and MMP‐2 indicate a cardiac remodeling phenotype in our model. This project shows that doxorubicin initiates changes to components of fibrosis, possibly driven by activation of the TGF‐β signaling pathway.
Lysyl Oxidase Inhibition Alleviates Fibrosis and Dysfunction in Rodents with Established Cardiac Disease
Authors: Ninh Van Kim , El Hajj Elia C , El Hajj Milad C , Mouton Alan J , Gardner Jason D 
Published: November 2023

Heart failure is the end result of many cardiovascular disorders, including myocardial infarction, hypertension, and diabetes. Regardless of etiology, a key mechanism of heart failure is adverse extracellular matrix (ECM) remodeling. Lysyl oxidase (LOX) is a collagen cross‐linking enzyme that is elevated in failing human hearts, and is associated with cardiac fibrosis. Our goal for this study was to determine if inhibition of LOX in rodents with established cardiac disease would provide protection against further adverse cardiac remodeling and dysfunction. The aortocaval fistula rat surgical model of volume overload (VO) was used. Eight weeks after surgery, both sham‐operated and VO rats were treated with a LOX inhibitor, beta‐aminopropionitrile (BAPN; 100 mg/kg/d). Treatment was administered for six weeks using an osmotic minipump inserted into the peritoneal cavity.Echocardiography was used to assess progressive alterations in cardiac remodeling and function. At 14 weeks, left ventricular (LV) catheterization was used to assess alterations in contractility, stiffness, and other indices of cardiac function. Using LV homogenates and fixed sections, interstitial myocardial collagen (immunohistochemistry), and protein expression of collagens I and III (Western Blot) were measured. Collagen cross‐linking was assessed using pyridinoline (Pyd) assay.VO induced significant LV hypertrophy (116% increase vs sham), diastolic LV wall stress (363% increase vs sham), fibrosis (172%, 77% and 22% increase in interstitial myocardial collagen, collagen I and collagen III, respectively, vs sham; p<0.05), and cardiac dysfunction (17% decrease in ejection fraction vs sham). LOX inhibition partially attenuated VO‐induced increases in LV hypertrophy (23% decrease vs VO; p<0.05). Inhibiting LOX also completely attenuated VO‐induced increases in interstitial myocardial collagen, and protein expression of collagens I and III (180%, 76% and 22% decrease, respectively, vs VO; p<0.05). LOX inhibition significantly attenuated increases in cardiac wall stress (33.5% decrease vs VO) and conferred cardioprotective effects as indicated by improved fractional shortening (19% increase vs untreated VO; p<0.05). LOX inhibition also significantly attenuated VO‐induced decreases in contractility, assessed using end systolic pressure‐volume catheterization and preload recruited stroke work (70% and 30% increase, respectively, vs VO; p<0.05). Overall, our data demonstrate the cardioprotective effects of LOX inhibition on the volume overload stressed heart, and its potential to slow or even prevent the transition to heart failure.Support or Funding InformationSupported by the NIH/NCRR #P20RR016456 and the American Heart Association Greater Southeast Affiliate #11GRNT7700002 (jdg).
Chloroquine Attenuates Klotho Gene Deficiency‐induced Arterial Stiffening and Hypertension by Suppression of Autophagy
Authors: Chen Kai , Sun Zhongjie 
Published: November 2023

Background & HypothesisHapodeficiency of the antiaging gene Klotho causes arterial stiffening and hypertension through unknown mechanisms. Our recent study showed that autophagy was upregulated in the aortas of Klotho mutant heterozygous (+/−) mice. We hypothesized that inhibition of autophagy by chloroquine (an anti‐malaria drug) attenuates Klotho deficiency‐induced arterial stiffening and hypertension.Methods & ResultsKlotho mutant heterozygous (+/−) mice and age‐ and sex‐matched wild‐type (WT) mice were used (20–23 months). Pulse wave velocity (PWV), a direct measure of arterial stiffness, and blood pressure (BP) were increased significantly in KL(+/−) mice. Interestingly, inhibition of autophagy by chloroquine reversed Klotho deficiency‐induced increases in PWV and BP within 2 weeks of treatment. The autophagy level, as measured by LC3I/LC3II and autophagy flux, was increased in aortas of KL(+/−) mice. Chloroquine abolished the upregulation of autophagy in Klotho (+/−) mice, indicating effective inhibition of autophagy. Klotho deficiency‐induced arterial stiffness was associated with accumulation of stiffer collagen and degeneration of compliant elastin fibers. In addition, the activity and expression of MMP2, MMP9, and the expression of TGF‐β1, TGF‐β3, RUNX2 and ALP were increased in aortas of KL(+/−) mice, which were attenuated by chloroquine. Scleraxis, a transcription factor in the regulation of collagen synthesis in arterial cells, was increased in aortas of KL(+/−) mice. The upregulation of scleraxis by Klotho deficiency was eliminated by inhibition of autophagy, which was further confirmed by inhibition of autophagy through siRNA knockdown of Beclin‐1 in mouse vascular aortic smooth muscle cells. Therefore, induction of autophagy is essential for Klotho deficiency–induced upregulation of scleraxis.ConclusionKlotho gene deficiency causes arterial stiffening and hypertension through upregulation of scleraxis in an autophagy‐dependent manner.Support or Funding InformationSupported by NIH R01 HL118558, DK093403, HL105302 and HL102074.
Circadian Rhythm of Pulse Pressure are decreased in Peroxisome Proliferator Activated Receptor‐α Knockout Mice during Angiotensin II Hypertension
Authors: Stukes Ian T , Reece Takisha , Lee Dexter L 
Published: November 2023

Circadian rhythm of pulse pressure is considered an index of cardiovascular disease. An elevated pulse pressure is commonly associated with increased stiffness of the aorta due to high blood pressure. Activation of PPAR‐a has been shown to decrease hypertension; however, the role of PPAR‐a on pulse pressure during Angiotensin II hypertension is not well understood. We tested the hypothesis that the absence of PPAR‐α would decrease changes in the circadian rhythm of pulse pressure during Angiotension II (Ang II) hypertension. Male (10 – 12 weeks old) PPAR‐alpha knockout (KO) mice and their wild‐type (WT) control were infused with Ang II (400 ng/kg/min) for 12 days. Day and night systolic, diastolic, pulse and mean arterial pressures, along with heart rate and locomotor activity was collected 19‐hrs/day. The average change in day to night pulse pressure was 1 ± .05 and 3 ± .1 mmHg in Ang II treated KO and WT mice, respectively. No differences in day to night heart rate were observed between KO (30 ± 3 bpm) and WT (30 ± 5 bpm). Day to night changes in locomotor activity, systolic, diastolic and mean arterial pressures were similar between both groups. TBARS were increased in KO + Ang II (15 ± 2 mM) vs WT + Ang II (11 ± 3 mM). Nitrite/Nitrate was decreased in KO + Ang II (1.0 ± 0.1 nM) vs WT + Ang II (1.5 ± 0.5 nM). Interleukin 17 was increased in KO + Ang II (1.5 ± 0.3 ng/mL) vs WT + Ang II (1.0 ± 0.2 ng/mL). Our results suggest that PPAR‐alpha activation increases the circadian rhythm of pulse pressure by decreasing oxidative stress, and IL‐17 concentrations while increasing nitrite/nitrate concentrations during Ang II hypertension.Support or Funding Information5K01HL092593‐05
Relationship between basilar artery vasomotion and blood pressure in normotensive and hypertensive rats
Authors: Tomiak‐Baquero Ana Maria , von Linstow Roloff Eva , Kasparov Sergey , Paton Julian F.R. 
Published: November 2023

Our group has previously hypothesised (Cates et al., 2012) that hypoperfusion of the brainstem is a contributing factor to the increased blood pressure (BP) in spontaneously hypertensive rats (SHR) in accordance with Cushing's mechanism. Artery vasomotion is a mechanism believed to increase tissue perfusion and oxygenation. In this study, we have assessed whether the basic characteristics of vasomotion in the basilar artery are present in the SHR in vivo and if there are differences between the SHR and normotensive Wistar rats. To our knowledge this is the first time vasomotion and vasoactivity of the basilar artery has been investigated in SHR and Wistar rat with the dura intact, thereby preserving physiological conditions. In addition it is the first time, to our knowledge, that SHR basilar vasomotion is studied in vivo. Under isofluorane anaesthesia, Wistar (n=3) and SHR (n=2) were kept at a constant temperature (37°C) and ventilated mechanically keeping end tidal CO2 around 4.5%. Arterial BP was monitored and a femoral vein cannulated for drug delivery. The ventral brainstem was exposed and the dura thinned to allow visualisation of the basilar artery from the vertebral bifurcation to the anterior inferior cerebellar arteries. Phenylephrine (20–50 μg/min) and sodium nitroprusside (0.6–4.2 μg/min) were injected i.v. to produce stepwise increases and decreases in blood pressure, respectively. In Wistar rats vasomotion occurred between 70 and 170 mmHg and confirms previous data (Fiji et al., 1990). In contrast, our pilot data suggests a higher pressure threshold (>90 mmHg) is needed before vasomotion is initiated in the SHR. We suggest that this may impede arterial perfusion and tissue oxygenation at lower blood pressures in the SHR compared to Wistar rats. These results support our notion of a hypoperfused brainstem in the hypertensive state.Support or Funding InformationThis project was funded by the BHF.