bluuebunny/crossref_metadata_2025_split huggingface dataset:
Leptin activates PKA via a novel mechanism to regulate KATP channel trafficking in pancreatic β‐cells
Authors: Cochrane Veronica , Shyng Show-Ling 
Published: April 2020

The adipocyte hormone leptin has a well‐established role in energy homeostasis via its actions in the central nervous system. In addition, leptin has been shown to have direct actions on peripheral tissues. In pancreatic β‐cells leptin inhibits insulin secretion by increasing conductance of ATP‐sensitive potassium (KATP) channels, which causes membrane hyperpolarization and reduces β‐cell electrical activity. There is evidence that disrupting leptin signaling at the β‐cell level may lead to excessive insulin secretion and contribute to insulin resistance and eventually type 2 diabetes. Recent studies have shown that leptin promotes KATP channel trafficking to increase KATP channel surface density and thereby KATP conductance in β‐cells. We found that leptin triggers a signaling pathway that involves potentiation of NMDA receptors, leading to an influx of calcium and activation of CaMKKβ, which then phosphorylates and activates AMPK; downstream of AMPK actin remodeling occurs in a PKA‐dependent manner that allows vesicles containing KATP channels to traffic to the β‐cell membrane. A knowledge gap in this pathway is whether PKA plays a permissive role or whether leptin signaling that results in AMPK activation leads to increased PKA activity for actin remodeling. Here we implement a FRET‐based PKA activity reporter to show that leptin signaling does indeed increase PKA activity and that this occurs via the NMDAR‐CaMKKβ‐AMPK signaling axis. Moreover, we provide evidence that the ability of leptin to regulate KATP channel trafficking requires that PKA is anchored to PKA anchoring proteins (AKAPs). AKAPs are scaffolding proteins known to organize signaling complexes for localized PKA signaling. Our results suggest that leptin signaling in β‐cells may be localized via a signaling complex involving AKAP to achieve spatiotemporal specificity. Additional studies into AKAP‐mediated organization of leptin signaling molecules in β‐cells will likely provide insight as to how leptin signaling may be disrupted in pathophysiological states such as type 2 diabetes.Support or Funding InformationNIH grant R01 DK57699 to SLS
PALMATINE ACTIVATES INSULIN RELEASE VIA PI3K – GLUT4 INSULIN DEPENDENT PATHWAY EX‐VIVO
Authors: Okechukwu Patrick Nwabueze , Ekeuku Sophia Ogechi , Sharma Mridula , Froemming Gabriele Ruth Anisah 
Published: April 2020

BackgroundPalmatine is a protoberberine alkaloid which identified to be the bioactive compound present in stem extract of Cosininum Fenestratum plant. Our previous research have reported the plasma glucose lowering activity of Palmatine and its effect on liver, kidney and antioxidant enzymes parameters in STZ induced diabetic rat model. We also reported that the molecular mechanism of action of palmatine insulin release is through activation insulin‐dependent pathway in vivo and in vitro.ObjectiveThe focus of this study was to determine the effect of Palmatine on insulin dependent signaling pathway in insulin resistance rat skeletal muscle ex‐vivo.MethodNormal Male SD rats (180–200g) were sacrificed and skeletal muscles were harvested. The smaller size skeletal muscles from rats were mounted in the Krebs‐Henseleit buffer (KHB) buffer to maintain the resting position. The tissues were then incubated at 37°C under 95% O2‐ 5%CO2 in Glucose free KHB containing 01% BSA and 1mM pyruvate for 1hr, and KHB in 500nmol/L insulin and 125nmol/L glucose for 24hrs. After incubation with insulin/glucose KHB, tissues were transferred to KHB buffer with 250mmol/L glucose for 5hrs, and then KHB with insulin for 30 mints. After induction tissue were replaced with fresh KHB drug was administered by pipetting drug into the organ bath and was allowed to incubate for 24hrs. RNA was extracted and converted to cDNA according manufacturer protocol and the expression of IRS‐1, PI3K, PKC, AKT2 and GLUT4 genes involved in insulin dependent signaling pathway were evaluated using qPCR.ResultPalmatine showed an increase in fold expression of PI3K, PKC, AKT2 and GLUT 4 compared to negative control. The result was similar to standard drug metformin. The increase in fold expression of the insulin dependent pathway genes shows they were revived as a result of Palmatine treatment.ConclusionPalmatine were able to rejuvenate PI3K, PKC, AKT2 and GLUT 4 in Palmatine treated group, which is usual impaired in insulin resistance skeletal muscle. The result is in consonance with the previous finding of in vitro and in vivo. Currently work is on‐going to investigate the effect of palmatine on the insulin‐independent pathway.Support or Funding InformationUCSI University
Activation of Nociceptive C‐fiber Subtypes in Mouse Skin by Bee Venoms
Authors: Jurcakova Danica , Undem Bradley J. 
Published: April 2020

Bee stings are extremely painful and in allergic subjects a cause of life‐threatening anaphylaxis. We have previously developed a dorsal thoracic skin‐nerve preparation to define sub‐groups of afferent C‐fibers innervating mouse skin. These comprise low mechanical threshold C‐fibers (C‐LTMs) which failed to directly respond to inflammatory mediators, and high mechanical threshold C‐fibers (C‐HTMs). The C‐HTMs could be further subdivided into two subgroups, one responding strongly to pruritogens such as histamine, chloroquine (CQ), BAM8‐22, and mast cells activation; the other failing to respond to these pruritogens, but respond strongly to 5‐HT and ATP (Mol Pharmacol. 2018, 94:1047–1056). Both types of C‐HTMs are activated by capsaicin. Here we evaluated the response of the two subgroups of C‐HTMs to venoms applied directly to the receptive fields in isolate skin. We evaluated the venom of honey bees, wasps and yellow jackets. Venom from each activated both types of C‐HTMs. Based on peak Hz of C‐fiber discharge, the relative strength of activation was: yellow jacket > honey bee ≈ wasp. CQ‐sensitive C‐fibers were activated by venoms to a greater extent than CQ‐insensitive C‐fibers. For example, bee venom evoked 6 ± 2 Hz (n=3) and 2 ± 0.4 Hz (n=7) in CQ‐sensitive vs CQ‐insensitive C‐fibers, respectively. Melittin, an active ingredient in bee venom mimicked the venoms in strongly activating C‐HTMs, with CQ‐sensitive being more strongly stimulated than CQ‐insensitive (9 ± 4 Hz (n=3) vs 1 ± 0.2 Hz (n=3), respectively). We hypothesize that CQsensitive C‐fibers are more strongly activated because unlike the CQ‐insensitive C‐HTMs, they can be stimulated as a consequence of mast cell activation (Neuroscience. 2019; 410:55–58). Indeed, melittin (10 μg/ml) caused mast cell activation (histamine release) in isolated skin fragments (76 ± 19 ng/g, above baseline, n=4); for comparison, compound 48/80 (30 μg/ml) evoked a net 203 ± 46 ng/g of histamine. The degree of melittin‐induced histamine release was not different between wildtype and MrgprB2 knockout mice, whereas compound 48/80 evoked histamine release only from the skin of wildtype mice. The data show that bee venom directly and strongly activates the terminals of virtually all high threshold nociceptive C‐fibers in mouse skin. The prurigentic subtype of C‐fibers are the most strongly activated, and this may be due to the additional indirect effect of mast cell activation, that occurs independently of MrgprB2 receptors.Support or Funding InformationThis work was supported by Department of Education, Slovakia (VEGA 1/0306/18).
Synergistic effect of sorafenib and resveratrol in human breast cancer MDA‐MB‐231 cells
Authors: lo bennett lunawati 
Published: April 2020

The incidence of breast cancer mortality is one of the major challenges in the scientific community. Despite advances in diagnosis and treatment options, death among women worldwide are still high.The desired outcome of the cancer therapies is to increase cellular apoptosis, to decrease the proliferative activity of the cancer cells, to minimize drug resistance, and to decrease the toxicity of the anticancer drugs. Sorafenib (SF), a component of ERK1/2 pathway, is a multi‐kinase inhibitor that target VEGFR‐1, VEGFR‐3, PDGFR‐h, and others. SF has been shown in the previous preclinical studies to slow cancer progression in human hepatocellular, renal, colon, pancreatic, thyroid, ovarian, lung, and breast cancer. The use of natural dietary antioxidants such as curcumin, resveratrol (RSV) in cancer treatment has gained popularity due to their minimal cytotoxic effects with no evidence of causing damage to normal cellular tissue. RSV is a natural polyphenol compound found in red grapes, berries, peanuts and other fruits with anti‐oxidant and chemo‐preventive properties. Several studies mentioned that RSV possesses potent anti‐cancer activity against human breast cancer by inhibiting cancer initiation, promotion, and progression.In the present study, RSV was studied as a chemo‐enhancing potential agent in combination with low dose of SF for the treatment of breast cancer using MDA‐MB‐231 cells. Cells viability measured by MTT assay (3‐[4, 5‐dimethylthiazol‐2‐yl] ‐2, 5‐diphenyl‐tetrazolium bromide), Hoechst33342, H2DCFDA, and Rhodamine123 staining using fluorescent microscope were conducted to determine cell viability, chromatin inducing apoptosis, intracellular generation of ROS, and mitochondrial membrane potential, respectively. Western Blot to detect different signaling protein expressions such as Casp‐3, Casp‐9, Casp‐8, P53, Bax, Bcl2, Apaf‐1, Smac/Diablo, MMP2, BRCA1, BRCA2, Bim, and Map kinases were conducted to test the hypothesis that RSV has efficacy with low dose of SF to decrease cancer cell proliferation and progression. The concentration of SF used was 3 μM and RSV was 50 μM. This finding suggests RSV can potentiate SF as anticancer drug in breast cancer treatment.Support or Funding InformationUnion University College of Pharmacy
Local Heating Mediated Vasodilation Increased 48 Hours After Remote Ischemic Preconditioning
Authors: Hinde Jurnie F. , Kim Jahyun , Barlow Sydney E. , Lang James A. 
Published: April 2020

IntroductionRemote ischemic preconditioning (RIPC), induced by brief periods of blood flow occlusion to a limb followed by reperfusion, protects distant tissues from ischemia‐reperfusion (IR) injury. A single bout of RIPC confers a delayed window of protection that begins 24 hrs after RIPC and last for 2–3 days; however, whether this timeline also applies to the microvasculature is unclear. We hypothesize that the hyperemic response to local heating will increase after a single bout of RIPC.MethodsSixteen healthy, young adults (7M, 9F) underwent a single session of RIPC, which consisted of four periods of inflating an arm cuff to 200mmHg for five min interspersed with five min of reperfusion. Laser speckle contrast imaging (LSCI) was used to measure the hyperemia response to local skin heating (Tsk = 42°C) at five time points; before treatment, and 24, 48, 72, and 168 hrs post‐RIPC. LSCI data are expressed as cutaneous vascular conductance (CVC = LSCI flux/mean arterial pressure).ResultsCompared to pre‐RIPC (1.58 ± 0.09 flux · mmHg−1), the vasodilation response to local heating was increased only at the 48‐hr post‐RIPC time point (24 hrs: 1.59 ± 0.10, 48 hrs: 1.69 ± 0.10, 72 hrs: 1.54 ± 0.13, 160 hrs: 1.53 ± 0.11 flux · mmHg−1).ConclusionThese results indicate that the modest increase in local‐mediation dilation exhibited a delayed response that peaked 48 hrs following a single RIPC bout. This suggests that a single bout of RIPC may have a protective effect on the microvasculature.Support or Funding InformationNASA – Iowa Space Consortium Grant
Particulate Matter Activates SIRT1‐SREBP1‐PIR Pathway to Promote Pulmonary Fibroblast Inflammation and Enhance Lung Fibrosis
Authors: Tien Chia-Ping , Chang Yu-Chan , Hung Shih-Chieh , Hsiao Michael 
Published: April 2020

Particulate matter (PM) is infamous for its strong connection with a variety of human disorders and diseases, including bronchitis, asthma, chronic obstructive pulmonary disease (COPD), cancer, allergy, stroke, Alzheimer’s disease, anxiety, cardiovascular disease, productive dysfunction, anemia, and diabetes. While mechanisms driving PM‐induced pathogenesis are poorly understood, it’s believed associated with PM’s unique character, small size with large surface area, allowing PM easily enters the body with a great amount of toxin attached. In an attempt to identify the microenvironment induced by PM, we treated human pulmonary fibroblasts (HPF) with different doses of PM, and our in vitro results showed that PM activated sterol regulatory element‐binding protein 1 (SREBP1) and its downstream PIRIN (PIR) and Nod‐like receptor protein 3 (NLRP3) inflammasome through downregulating Sirtuin1 (SIRT1). Our further in silico analysis revealed that overexpression of PIR was related to tobacco and consistent with early COPD, while our IHC analysis reported the correlation of PIR with PM from lung tissues of PM‐fed mouse models. Taken together, we concluded that PM caused lung fibrosis and COPD via SIRT1‐SREBP1‐PIR/ NLRP3 inflammasome axis, which may provide several plausible therapeutic targets for PM‐related adverse sequelae.Support or Funding InformationThis work was supported by grants from Academia Sinica and Ministry of Science and Technology [MOST 104‐0210‐01‐09‐02, MOST 105‐0210‐01‐13‐01, and MOST 106‐0210‐01‐15‐02] to Michael Hsiao.
Identification of a novel player in insulin‐mediated lipolysis inhibition
Authors: Zadoorian Armella , Stoeckli Jacqueline , James David Ernest 
Published: April 2020

Lipolysis is a tightly regulated catabolic process essential for maintaining whole‐body energy homeostasis. It exists in a dynamic balance between activation by β‐adrenergic stimulation during starvation or prolonged exercise, and inhibition by insulin following nutrient intake. Dysregulation of lipolysis can lead to ectopic fat accumulation in the blood and insulin‐sensitive tissues, encouraging the development of metabolic disorders such as type 2 diabetes and non‐alcoholic fatty liver disease. Despite this, the mechanism by which insulin regulates lipolysis remains controversial and incomplete. The prevailing model hinges on the enzymatic function of the Akt substrate, phosphodiesterase 3B (PDE3B) in explaining insulin’s antilipolytic action. However, several studies have challenged this and suggested that whilst PDE3B is essential, its function alone cannot explain this regulation. Instead, we implicate another protein, α/β‐hydrolase domain‐containing protein 15 (ABHD15) as a novel player in insulin‐mediated lipolysis inhibition. Through stable knockdown or knockout of ABHD15 in 3T3‐L1, brown or fat explant adipocytes, we demonstrate a significant defect in insulin’s inhibition of lipolysis that is rescued upon ABHD15 re‐expression. Moreover, through the characterisation of ABHD15 and PDE3B mutants lacking novel insulin‐regulated phosphorylation sites previously identified by our lab, we have explored a putative mechanism by which these proteins facilitate insulin’s inhibition of lipolysis. In summary, we have identified a novel regulator of lipolysis that will likely shed light on the mechanism of this important process.Support or Funding InformationAustralian Government Research Training Program Scholarship, The Chen Family Research Scholarship.
Investigating the mechanism by which Naproxen and Prometryn causes Cardiovascular dysfunction
Authors: Sule Rasheed , Gomes Aldrin 
Published: April 2020

Background and ObjectiveCardiovascular disease (CVD) is the leading cause of death and a major cause of disability worldwide. Previous studies have shown that the long‐term and chronic use of nonsteroidal anti‐inflammatory drugs (NSAIDs) increases the risk of developing stroke and cardiovascular diseases. Naproxen is an FDA‐approved NSAID that is currently used to treat several medical conditions such as pain, osteoarthritis, rheumatoid arthritis, polyarticular juvenile idiopathic arthritis, tendonitis, etc. Acetaminophen, the active ingredient in Tylenol, is not an NSAID but it has been associated with increased risk of liver toxicity. Similarly, the long‐term exposures to pesticides such as Prometryn amongst others have been established to be dangerous to human lives and capable to disrupt the physiology of different organs in the body, including the cardiovascular system. Prometryn, a diamino‐1,3,5‐triazine, is used as a selective pre‐ and post‐emergence herbicide. It is used to control annual grasses and broadleaf weeds in cotton and celery. This study aimed to investigate the effects of Naproxen, Acetaminophen, and Prometryn in cardiomyocytes and the underlying mechanisms by which it causes cardiovascular dysfunction.MethodsThe embryonic cardiomyocyte cell line H9c2 is commonly used in numerous in vitro studies because morphological parameters of their cells resemble immature embryonic cardiomyocytes. It has been previously shown that H9c2 cell line and primary neonatal cardiomyocyte cells show similar hypertrophic responses in vitro. H9c2 cardiomyocytes were plated in a 96 well plate at a concentration of 4000 cells/well. The cells were then treated with different concentrations of Naproxen, Acetaminophen, and Prometryn for 24h at 37°C and 5% CO2. The cell viability, reactive oxygen species (ROS) formation, and mitochondrial membrane potential (ΔΨm) were examined.ResultsH9c2 cells treated with 100μM Acetaminophen and 20μM Prometryn showed significant decreases (> 30%) in cell viability. Hydrogen peroxide (H2O2), which was used as a positive control, also resulted in significant decreases in cell viability at 100μM. ROS formation was significantly increased in the presence of 200–400μM Naproxen. Acetaminophen showed significant amount of ROS formation at a higher concentration of 200μM while Prometryn also showed a significant increase in ROS formation at a higher concentration of 30μM. The effect of varying concentrations of Naproxen showed that ΔΨm was decreased by ~30% at 100μM. Prometryn decreased ΔΨm by ~20% at 10–20μM while Acetaminophen also decreased ΔΨm by ~20% at 100–200μM.ConclusionThese results suggest that both concentration and exposure time are important for NSAID‐induced cardiotoxicity. Acetaminophen, which is not an NSAID, increased ROS generation and decreased ΔΨm at higher concentration. This experimental data suggests that Naproxen, Acetaminophen, and Prometryn causes cardiomyocyte dysfunction at varying concentrations.
Microglial Involvement in Stress‐induced Prolonged Sympathetic Nervous Excitation in Rats
Authors: Yoshizawa Masashi , Fukushi Isato , Takeda Kotaro , Kono Yousuke , Hasebe Yohei , Koizumi Keiichi , Toda Takako , Okada Yasumasa 
Published: April 2020

Hypertension is one of the most important risk factors causing cardiovascular diseases. It has been assumed that hypertension is caused by continuous over‐excitation of the sympathetic nervous system, which is often accompanied by psychological stress. We have previously reported that glial cells, especially astrocytes, are importantly involved in blood pressure elevation during stress and post‐stress recovery period in air jet stress loaded rats. However, it has not been well clarified whether another glial cell, microglia, is also involved in stress‐induced sympathetic nervous excitation. In the present study, we aimed to address this issue using adult rats (n=9, 23–26 weeks age, body weight 300–467g). A blood pressure telemeter was implanted intraperitoneally with a pressure transducer tip in the abdominal aorta under anesthesia. After at least one week recovery period, blood pressure and pulse rate responses to psychological stress were measured in an unanesthetized freely moving condition by blood pressure telemetry system (Kaha Sciences, Auckland, New Zealand). Measurement was first conducted without pretreatment with minocycline, which is an inhibitor of microglial activation. Then, in more than one week after this control measurement, the animal was pretreated with minocycline (25mg/kg/day) for three consecutive days, and blood pressure and pulse rate responses to stress were again measured under the suppression of microglial activation. Air jet stress was loaded to the rat by blowing compressed air to the face of the animal (10L/min, 15min). We recorded blood pressure and pulse rate before, during and after the stress loading, and compared these data between the conditions before and after minocycline pretreatment. Pretreatment with minocycline did not affect either blood pressure or pulse rate in a pre‐stress resting condition. However, after pretreatment with minocycline, stress‐induced augmentation of both blood pressure and pulse rate were attenuated during and after air jet stress loading with statistical significance (paired t‐test). These findings indicate that activated microglia is involved in the augmentation of sympathetic nervous activity during and after stress loading.Support or Funding InformationThis work was supported by JSPS KAKENHI Grant Numbers 17K08559, 17H05540, 18K17783, 19K17386 and 19K17620 and a Grant‐in‐aid of the Cardiovascular Research Fund, Tokyo, Japan.
Deletion of the Microtubule‐associated protein tau (Mapt−/−) results in diastolic heart failure and altered skeletal muscle function in vivo
Authors: Rajalingam Sahith , Kambrath Anuradha Valiya , Vidal Ruben , Willis Monte S. 
Published: April 2020

According to 2019 statistics, Alzheimer’s affects 5.8 million Americans. It is an undertreated disease with increased prevalence. The microtubule‐associated protein tau (Mapt) gene encodes the Tau protein, which plays a crucial role in the pathology and progression of Alzheimer’s disease in the brain. The Tau protein interacts with microtubules and plays a role in neuronal microtubule stability. Surprisingly, Tau is equally expressed in the heart, skeletal muscle, kidney, adipose, and soft tissue at the protein level, and its function is mostly unknown. Since microtubule stability plays an essential role in cardiac function, we hypothesized that Mapt−/− mice would develop cardiac dysfunction and skeletal muscle function in vivo. In the present study, we investigated both cardiac function and skeletal muscle phenotypes at 12 months of age. Conscious echocardiography (VisualSonics Vevo 2100) and ECG analysis (ECGenie) was performed in male and female Mapt−/−. Mice and compared to age‐ and strain‐matched wildtype controls. Echocardiographic analysis identified an “apparent” increase in Mapt−/− systolic dysfunction compared to wildtype mice (EF%: 83.4±1.9 vs. 79.1±1.5, FS%: 51.5±2.0 vs. 46.9±1.5%, N=6, 7, respectively) at 12 months of age, although both systolic and diastolic LV volumes were significantly decreased in the Mapt−/− mice. Parallel Doppler studies of the mitral valve E/A ratio (1.5±0.4 vs. 2.3±0.5) identified a significant diastolic (relaxation) dysfunction, which may be driving the “apparent” systolic dysfunction and consistent with the clinical parameters of heart failure with preserved ejection fraction (HFpEF). Electrophysiologic analysis of Mapt−/− mice at 12 months of age identified a significantly decreased heart rate (and corresponding increased RR interval), with evidence of an increased heart rate variability (e.g., CV%) indicative of autonomic changes in the heart. No other changes in ECG intervals (i.e., PQ, PR, QRS, QT, ST, QTC ) or ECG amplitudes (SR, R) were identified. These studies demonstrate the Tau protein’s role for the first time in cardiac and skeletal muscle function phenocopying clinically relevant heart failure (HFpEF), characteristic of patients with Alzheimer Disease in recent small studies. Furthermore, these studies indicate that anti‐Tau therapies for Alzheimer Disease currently in development for primary brain disease could potentially have unexpected off‐target effects that should be considered, particularly since heart failure and skeletal muscle weakness in the AD patients is associated common co‐morbidities and mortality.Support or Funding InformationLilly Foundation/Indiana Center for Musculoskeletal Health/ IU School of Medicine, Physician Scientist Initiative, Scientific Research Initiative