bluuebunny/crossref_metadata_2025 huggingface dataset:
Exercise Mitigates Angiotensin II-Mediated Sympathetic Nerve-Macrophage Interaction in Aortic Adventitia Leading to Vascular Remodeling
Authors: Cho Jae Min , Vu Khoa , Zhu Enbo , Roustaei Mehrdad , Nahoul Jonah , Park Seul-Ki , Chapleau Mark W.
Published: May 2024

Large artery stiffness is a significant risk factor for cardiovascular diseases. Our previous study suggested that angiotensin II (Ang II) stimulates sympathetic innervation in aortic adventitia (AA) leading to elevated mean arterial blood pressure and increased arterial fibrosis, while voluntary wheel-running (VWR) reduces them. The aim of this study is to explore mechanism under Ang II-induced the aortic remodeling through sympathetic nerves and immune cell interactions using transcriptomics. We isolated cells in AA from Ang II (1.5 mg/kg/day) vs. Vehicle (Saline) infused C57BL/6 male mice (n=3 of each group), and we performed single-cell RNA-sequencing (scRNAseq). We profiled 23,419 cells after quality control and filtering steps and annotated 9 cell types in the AA employing a uniform manifold approximation and projection (UMAP) to visualize the remaining cells and the Leiden cluster algorithm. Firstly, we identified the Adrb2 gene for β2-adrenergic receptor (β2-ADR) was predominantly expressed in macrophages/monocytes as compared to other cell types, and significantly more expressed in macrophages vs. monocytes (adjusted p-value, <0.05). We validated the transcriptomic results using immunostaining for β2-ADR and synapsin with CD68 in AA. In addition, Ang II increased AA macrophage proportion which displays M1 phenotype (pro-inflammatory) (adjusted p-value, <0.05). These findings suggest that Ang II promotes M1 like macrophages which interact with sympathetic nerves in AA. Next, we performed Gene Ontology (GO) enrichment test in macrophages and fibroblasts. Ang II Macrophages were enriched in GO terms with inflammation and cytokines, and Ang II fibroblasts were enriched in GO terms involved in extracellular matrix deposition. The GO results indicate that Ang II induced inflammatory macrophages activates fibroblasts to accumulate ECM deposition in AA. Congruent with the scRNAseq results, we found that number of macrophages, ECM accumulation, and vascular stiffness measured by pulse wave velocity were increased with Ang II vs. Vehicle (all, p <0.05), whereas interestingly VWR ameliorated the Ang II effects. This study provides the evidence that Ang II promotes aortic remodeling by interaction between sympathetic nerves and macrophage which results in ECM deposition in AA using transcriptomics approach, while VWR countermeasure to these detrimental effects.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Hepatokine ITIH3 Protects Against Hepatic Steatosis by Downregulating Mitochondrial Bioenergetics and De Novo Lipogenesis
Authors: Kumar Talari Noble , Mattam Ushodaya , Kaminska Dorota , Sotomayor-Rodriguez Irene , Rahman Afra , Péterfy Miklós , Pajukanta Päivi
Published: May 2024

Accumulating evidence suggest that mitochondrial functions are altered and contribute to the pathogenesis of non-alcoholic fatty liver disease (NAFLD). As a result, research is being conducted to discover targets that alter mitochondrial functions to ameliorate NAFLD, and its progression towards non-alcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC). Recent studies demonstrate that liver secretory proteins regulate normal development, obesity, simple steatosis to NASH progression. Inter-α-trypsin inhibitors (ITI) are one such proteins secreted by liver, altered in NAFLD, but their functional importance in mitochondrial metabolism is poorly understood. Here, we have identified that ITIH3 is a potential candidate gene that protects against NAFLD by targeting mitochondrial metabolism. We used an integrative multiomics approach using transcriptomic data from approximately 100 different mouse strains called hybrid mouse diversity panel (HMDP) and a cohort of bariatric surgery patients and identified Itih3/ITIH3 expression to be inversely associated with NAFLD/NASH progression and hepatic TG accumulation. Our network enrichment analyses revealed NAFLD-related pathways such as mitochondria, TCA cycle, fatty acid metabolism, cholesterol metabolism, coagulation and fibrinolysis. Next, disease enrichments by ToppGene revealed metabolic syndrome-related disease traits including dyslipidemia, steatosis, NASH and fibrosis. Our in vitro and in vivo studies using loss and gain of function mouse and cell culture models demonstrated that hepatic ITIH3 reduced liver triglyceride accumulation and de novo lipogenesis (DNL). Remarkably, hepatic ITIH3 also lowered mitochondrial respiration and lipid droplet accumulation. This was accompanied by increased STAT1 signaling and Stat3 expression, both of which are known to protect against NAFLD/NASH. Together, we conclude that ITIH3 plays a unique role in regulating the hepatic lipid profile, DNL, and mitochondrial metabolism, all of which have implications for NAFLD treatment. Our findings indicate hepatokine ITIH3 as a potential biomarker and/or treatment for NAFLD.

R00DK120875.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Mitochondrial Ca2+-coupled generation of reactive oxygen species causes endothelial dysfunction in Cantú syndrome
Authors: Metwally Elsayed , Yamasaki Evan , Solano Alfredo Sanchez , Thakore Pratish , McClenaghan Conor , Nichols Colin G. , Earley Scott
Published: May 2024

Cantú syndrome is a multisystem disorder caused by gain-of-function (GOF) mutations in KCNJ8 and ABCC9, the genes encoding the pore-forming inward rectifier Kir6.1 and regulatory sulfonylurea receptor SUR2B subunits of vascular ATP-sensitive K+ channels (KATP). In this study, we investigated the effects of Cantú syndrome on the vascular endothelium using mutant mice that model the disease. We found that endothelium-dependent dilation was impaired in small mesenteric arteries from Cantú mice. Loss of endothelium-dependent vasodilation led to increased vasoconstriction in response to intraluminal pressure and to the adrenergic receptor agonist phenylephrine. We also found that KATP GOF and acute activation of KATP channels with pinacidil increased the amplitude and frequency of wave-like Ca2+ events that were generated in the endothelium in response to the vasodilator agonist carbachol (CCh). Elevated cytosolic Ca2+ signaling activity in arterial endothelial cells from Cantú mice was associated with high mitochondrial [Ca2+], reactive oxygen species (ROS) generation, and peroxynitrite levels. Scavenging intracellular and mitochondrial ROS restored endothelium-dependent vasodilation in the arteries of mice with KATP GOF mutations. We conclude that mitochondrial Ca2+ overload and ROS generation cause endothelial dysfunction in mice with Cantú syndrome.

This study was supported by grants from NHLBI (R35HL155008) and NIGMS (P20GM130459) to S.E., and NIH (R35HL140024) to C.G.N., and NIH (R00HL150277) to C.M. The Transgenic Genotyping and Phenotyping Core and the High Spatial and Temporal Resolution Imaging Core at the COBRE Center for Molecular and Cellular Signaling in the Cardiovascular System, University of Nevada, Reno is maintained by grants from NIH/NIGMS (P20GM130459).

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Autotaxin-Lysophosphatidic Acid Axis: Key Regulator of Blood-Brain Barrier Integrity and Stroke Outcomes during Cerebral Ischemia-Reperfusion
Authors: Panchatcharam Manikandan , Bhattarai Susmita , Manikandan Shrivats , Manikandan Varsha , Miriyala Sumitra
Published: May 2024

Background: Endothelial hyperpermeability subsequent to ischemic stroke poses severe ramifications for patient outcomes, with the preservation of blood-brain barrier (BBB) integrity being paramount. The pathological role of the autotaxin-lysophosphatidic acid (ATX-LPA) axis in various disorders is established. While LPA's detrimental effects in stroke pathology have been documented, the mechanistic role of its enzymatic precursor, autotaxin (ATX), especially in the context of BBB disruption and mitochondrial dysfunction, necessitates deeper exploration.Objective: Our research aimed to dissect the intricate interplay of the ATX-LPA axis in modulating BBB integrity and mitochondrial bioenergetics during cerebral ischemia-reperfusion injury.Methods: Employing well-characterized murine models, ischemic strokes were meticulously induced, succeeded by reperfusion. A gamut of advanced assays—including the electrical cell-substrate impedance sensor, Seahorse XF24 analyzer, and AR-2 probe fluorescence—were systematically deployed. Moreover, to attain a nuanced understanding, we genetically engineered a mouse model exhibiting endothelial-specific ATX deletion, facilitating a direct interrogation of ATX's endothelial role.Results: Post-ischemic reperfusion culminated in a statistically significant upregulation of ATX mRNA (1.7-fold, p<0.05) and a quadrupled surge in its enzymatic activity (p<0.01). Disturbingly, the I/R cohort manifested augmented LPA concentrations, concomitant with a pronounced mitochondrial bioenergetic collapse, evidenced by metrics such as the oxygen consumption rate and ATP synthesis (both p<0.01). BBB integrity was critically compromised, a derangement that ATX inhibitors ameliorated (p<0.05). Intriguingly, mice with endothelial-specific ATX ablation exhibited remarkably attenuated permeability (p<0.05) and infarct volumetric reductions (p<0.01), while preserving cerebral perfusion (p<0.05).Conclusion: Our findings underscore the ATX-LPA axis as a linchpin in the pathophysiological cascade following ischemic stroke, specifically impinging on BBB and mitochondrial health. Deciphering and subsequently targeting this nexus could herald a paradigm shift in therapeutic strategies for ischemic stroke.

This research was supported by National Institutes of Health grants HL141998, HL141998-01S1, AA025744, AA026708, and AA025744-02S1.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Influence of home-based heat therapy on thermal and cardiovascular strain during passive heat exposure in older adults
Authors: Cope Heidi L. , Richey Rauchelle E. , Ruiz Ysabella I. , Moore Amy M. , Olivencia-Yurvati Albert H. , Garfield Tyson C. , Gagnon Daniel
Published: May 2024

Heat waves are occurring more frequently and with greater intensity. In fact, 2023 marked the hottest summer ever recorded in the Northern Hemisphere. Heat waves increase the risk for heat-related morbidity and mortality, particularly for older adults who have a reduced ability to dissipate heat. Heat acclimation induces physiological adaptations that attenuate thermal and cardiovascular strain during subsequent heat exposures. However, traditional heat acclimation protocols require expensive equipment (e.g., climate chamber) and may be challenging for older adults with limited functional capacity. Home-based heat therapy provides a potentially safe and pragmatic option to induce heat acclimation. The purpose of this pilot study was to test the hypothesis that home-based heat therapy reduces thermal and cardiovascular strain in older adults during acute passive heat exposure. Six older adults (5 women; 67 ± 4 years) performed 8 weeks of home-based heat therapy by immersing their lower legs ~33 cm into a heated (~ 42°C) and circulated water bath 4 days per week, for 45 min per session. Intestinal temperature (telemetric pill) and heart rate were assessed before (pre) and after (post) the intervention during acute heat exposure (45 min lower leg water immersion). In addition, rate pressure product, an estimate of myocardial demand, was calculated as heart rate x systolic blood pressure. Resting intestinal temperature, heart rate, and rate pressure product did not differ from pre to post heat therapy (all P ≥ 0.6). However, the change in intestinal temperature during acute heat exposure was reduced after heat therapy (15 min: pre, Δ0.47 ± 0.17 °C vs. post, Δ0.33 ± 0.14 °C; 30 min: pre, Δ0.84 ± 0.29 °C vs. post, Δ0.72 ± 0.23 °C; 45 min: pre, Δ1.10 ± 0.27 °C vs. post, Δ1.07 ± 0.24 °C; P = 0.03 for main effect of time). Likewise, the change in heart rate was attenuated following the intervention (15 min: pre, Δ14 ± 9 bpm vs. post, Δ10 ± 5 bpm; 30 min: pre, Δ22 ± 13 bpm vs. post, Δ17 ± 6 bpm; 45 min: pre, Δ25 ± 9 bpm vs. post, Δ21 ± 6 bpm; P = 0.02 for main effect of time). Rate pressure product was also reduced following heat therapy (15 min: pre, Δ1280 ± 1636 bpm·mmHg vs. post, Δ322 ± 698 bpm·mmHg; 30 min: pre, Δ1800 ± 1573 bpm·mmHg vs. post, Δ1170 ± 450 bpm·mmHg; 45 min: pre, Δ2145 ± 593 bpm·mmHg vs. post, Δ840 ± 602 bpm·mmHg; P < 0.01 for main effect of time). Our preliminary data suggest that 8 weeks of home-based heat therapy elicits some adaptations that may reflect heat acclimation. However, further work is needed to confirm these initial findings.

American Heart Association TPA958179.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Skeletal Muscle Extracellular Vesicles Enhance Mitochondrial Movement and have a Dose-dependent Effect on Increasing Mitochondrial Respiration
Authors: Goebel de Souza Tamiris de Fatima , Seif Samira , O Obi Patience , Ajenkar Anass , Chandrasena Hashini , Tuma Aya , Bydak Benjamin
Published: May 2024

Chronic exercise leads to systemic health benefits across tissues, including an increase in mitochondrial function in skeletal muscle. One potential mechanism is via the release of extracellular vesicles (EVs), which can transfer functional cargo to recipient cells. Previously, we have shown that using an in vitro model of exercise, chronic contractile activity (CCA)-derived EVs (CCA-EV) increased mitochondrial biogenesis in healthy myoblasts. Here, we hypothesize that CCA-EVs will have a concentration-dependent effect on mitochondrial respiration, and also regulate mitochondrial dynamics in myoblasts. C2C12 myoblasts were differentiated into myotubes, and electrically paced (3hrs/day, 4 days, 14V, C-PACE EM, IonOptix). EVs from control and CCA-stimulated myotubes were isolated from conditioned media using differential ultracentrifugation and biophysically characterized by size and concentration using TRPS (Izon). C2C12 myoblasts were treated daily for 4 days using three different concentrations: 1.0E4; 2.0E4 and 4.0E4 EVs/cell (N=4-5). Basal and maximal oxygen consumption rates (OCR) were measured using the Seahorse XFe24 (Agilent). We used live-cell fluorescence microscopy and Mitometer software to access mitochondrial movement: area/volume, displacement, distance, length, perimeter, speed and velocity. Average size was unchanged between control-EVs (123±10.8 nm) and CCA-EVs (123±11.9 nm) (p=0.9137, N=3), and 2.3-fold more CCA-EVs were released vs. control-EVs (p=0.2072, N=3). Lowest EV concentration (1.0E+4 EVs/cell, N=5) had no effect on basal (p=0.4226) and maximal (p=0.1835) OCR. Intermediate dosage of CCA-EVs (2.0E+4 EVs/cell, N=5) increased basal OCR by 20% (p=0.0037) and maximal OCR by 18% (p=0.0095), while the highest concentration (4.0E+4 EVs/cell, N=4) decreased basal OCR by 9% (p=0.0001) and maximal OCR by 29% (p=0.0009), compared to control-EVs. Mitochondrial motility (N=484-976) in myoblasts treated daily after each day of CCA showed enhanced mitochondrial dynamics with CCA-EVs: increased area/volume (p<0.0001), displacement (p<0.0001), distance (p<0.0001), mean intensity (p<0.0001), perimeter/surface area (p=0.0137) and speed (p<0.0001), compared to control-EVs. In summary, CCA-EVs induced concentration-dependent improvements in mitochondrial respiration in healthy myoblasts, concomitant with enhanced mitochondrial movement. These results open exciting avenues for the therapeutic potential of CCA-EVs in rescuing mitochondrial dysfunction.

TFGS is funded by a Research Manitoba Postdoctoral Fellowship. Grants from CHRIM, CHF, DREAM and NSERC to AS funded the research.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Augmented pressor responses to mental stress in females with spontaneous coronary artery dissection
Authors: Zaremba Solomiia , Dillon Gabrielle , Miller Alex , Harvey Ronée , Hayes Sharonne , Baker Sarah , Tweet Marysia
Published: May 2024

Background: Spontaneous coronary artery dissection (SCAD) causes acute coronary syndrome or sudden cardiac death due to a separation of arterial wall layers. The majority of patients with SCAD are females (>80%) with few to no traditional cardiovascular risk factors. Though the physiological mechanisms that predispose to SCAD are unknown, common triggers for SCAD events include sympathoexcitatory stimuli, such as mental and emotional stress. Additionally, studies report high prevalence of depression and anxiety among patients with SCAD. Our study aimed to investigate cardiovascular responses to mental stress in patients with SCAD. We hypothesized that patients with SCAD would have exaggerated cardiovascular responses to mental stress compared to healthy controls. Methods: Four female patients with SCAD were age-, and BMI-matched with 4 healthy females. Participants underwent 2 minutes of baseline quiet rest, a 5-minute Stroop Color Word Test to induce mental stress, followed by 2 minutes of recovery. Continuous beat-to-beat blood pressure (BP, finger photoplethysmography) and heart rate (HR, 3-lead ECG) were recorded. Venous occlusion plethysmography was used to measure forearm blood flow (FBF). Forearm vascular conductance (FVC) was calculated as FBF/mean BP×100. Data are presented as change from baseline (Δmean±SD). Group data were compared using independent samples t-tests. Results: Resting hemodynamic parameters (Systolic [SBP], Diastolic [DBP], and Mean BP [MBP], Pulse pressure [PP], and HR) and FVC were similar between groups. Patients with SCAD had greater increases in DBP (Δ12±5 vs. Δ1±5 mmHg, p=0.02) and PP (Δ5±3 vs. Δ-7±8 mmHg, p=0.04) during the last minute of mental stress test compared to controls. Although, there were no differences in the changes of SBP (Δ17±7 vs. Δ-1±13 mmHg, p=0.05), MBP (Δ13±6 vs. Δ3±8 mmHg, p=0.08), HR (Δ8±0 vs. Δ10±2 bpm, p=0.12), or FVC (Δ1.5±1.2 vs. Δ1.8±1.3 ml/min/100 mmHg, p=0.80) between groups. During the last minute of recovery, there were no differences in hemodynamic parameters (SBP: Δ6±9 vs. Δ-4±10 mmHg, p=0.23; DBP: Δ2±7 vs. Δ-3±2 mmHg, p=0.22; MBP: Δ3±7 vs. Δ-3±5 mmHg, p=0.22; PP: Δ4±5 vs. Δ-1±8 mmHg, p= 0.35; HR: Δ-1±3 vs. Δ0±3 bpm, p=0.64), or FVC (Δ1.3±1.7 vs. Δ0.5±0.3 ml/min/100 mmHg, p= 0.35) between groups. Conclusion: These preliminary data suggest that patients with SCAD have greater increases in DBP and PP in response to mental stress compared to healthy controls. These exaggerated pressor responses might have implications for the pathophysiology of SCAD.

NIH K23 HL155506, T32 DK07352, K01 HL148144, UL1 TR0022377, and AHA 898649.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Modulation of WNT signalling by inflammatory factor TWEAK, and its consequences on fibroblast-epithelial communication
Authors: Raphael Bella , Matellan Carlos , Manresa Mario
Published: May 2024

BACKGROUND AND AIMS: A single layer of epithelial cells that are supported by resident mucosal fibroblasts, provides an intestinal barrier against pathogens. In Inflammatory Bowel Disease (IBD), this barrier is disrupted by mechanisms which are poorly understood. Intestinal fibroblasts produce WNT, BMP and Notch mediators that contribute to epithelial homeostasis and an impairment on these signals results in the loss of barrier integrity which has been observed in IBD. In fact, fibroblasts producing these signals may be lost during inflammation. Yet the mediators and mechanism that drive this loss of homeostatic stromal-derived signals are unknown. TWEAK is a member of the tumour necrosis factor superfamily (TNFSF) that was found to be upregulated in IBD biopsies and dysregulated tissue repair and promote chronic inflammation in in vivo murine models. However, whether TWEAK exerts its effects on fibroblasts and how these may contribute to barrier breakdown remains unknown. My central hypothesis is that TWEAK dysregulates the crosstalk between fibroblasts and epithelial cells in the intestinal tract by impairing a homeostatic signalling network. METHODS: To assess the effect of TWEAK on WNT signalling and wound healing in fibroblasts and epithelial cells, the expression of WNT ligands and receptors were assessed. Primary human colonic fibroblasts and human colonic epithelial cells were stimulated with TWEAK at various time points and analysed by qPCR, Western blot and Flow cytometry and scratch wound assay. RESULTS: Both Fibroblasts and epithelial cells displayed abundant Fn14 surface receptor, although epithelial cells at a level lower than that found on colonic fibroblasts. Transcriptional signatures at gene RSPO2 (0.5-fold ± decrease, *p<0.05, n=4), WNT5A (1 fold ± decrease, **p<0.01, n=4) and BMP6 (1 fold ± decrease, ***p<0.001, n=4) and protein level RSPO2 (50% ± decrease respectively, n=5) showed a TWEAK-mediated suppression after prolonged exposure (24-48h), but not in epithelial cells. Moreover, TWEAK delayed fibroblast healing capacity after 24h (50% ± decrease in wound closure, n=4) in a wound-scratch assay. CONCLUSION: TWEAK represses the expression of homeostatic factors in colonic fibroblasts but not on epithelial cells, suggesting this mechanism could be specific to the intestinal stroma. The effect that this impairment of WNT signals in stromal cells may have on their differentiation and communication with the epithelium will be subject for further study.

UCD Ad Astra PhD Scholarship.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Life in the Slow Lane: The Rate of Protein Synthesis Is Slower in the Protoendothermic Tenrec than the Boreoeutherian Golden-Mantled Ground Squirrel
Authors: Carlson Zachary , Hindle Allyson G , van Breukelen Frank
Published: May 2024

In order to address mechanisms of how hibernating mammals depress protein synthesis during torpor, we developed primary cell cultures from golden-mantled ground squirrels (Spermophilus [Callospermophilus] lateralis) and tenrecs (Tenrec ecaudatus). During torpor in squirrels, there is an acute uncoupling of translational initiation and elongation at body temperature (Tb) = 18°C as animals enter torpor. As a result, there are robust changes to the polysome profile of squirrels depending on state. Protein synthesis is depressed to 0.23 to 0.5% of active rates during torpor. In the bizarre, Afrotherian Tenrec ecaudatus, metabolism and Tb are remarkably plastic. Tenrecs may be fully active with a Tb of 12 °C or hibernating at a Tb of 28 °C. Moreover, oxygen consumption rates may vary 25 fold in active tenrecs. With this high variability in Tb, one might expect that these tenrecs might not be able to use Tb to control protein synthesis. Liver polysome profiles were confusing- there were no real changes between states or temperature. Rather, all tenrecs had a rather modest polysome profile with little heavy material typical of very active protein synthesis. To address this, we developed liver (do not grow well) and kidney cell (grow very well) cultures from ground squirrels and tenrecs. Our results indicate that the translation rate in tenrec primary cells is ~30 % of the translation rate in golden-mantled ground squirrel (p < 0.05). We interpret these results as tenrecs living ‘Life in the Slow Lane.’ By experiencing these low rates of a process critical to homeostasis, we contend tenrecs are avoiding rapid changes as a consequence of their rapid changes in Tb or metabolism. In effect, ‘driving slowly’ allows a tenrec to avoid major accidents which would imperil the animal. Perhaps not surprisingly, tenrec litters are enormous with as many as 32 confirmed young in a single litter.

This research was supported by the Translational Research Institute for Space Health (TRISH).

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Sex-Dependent Increases of Hepatic Acylcarnitines by Myocardial Infarction
Authors: Wurm Daniel , Dai Wujing , Gu Haiwei , Chen Qin M.
Published: May 2024

Many different diseases and environmental stressors can lead to an increase in oxidative stress. Urban air pollution leads to inhalation of airborne particulate matter in high traffc environments. This has been linked to chronic oxidative stress and increased risk or severity of myocardial infarction (MI). MI is one cause of acute oxidative stress. A key player for cellular defense against oxidative stress is activation of Nrf2, a transcription factor that controls the expression of key antioxidant and cytoprotective genes. Although Nrf2 has been reported to regulate genes for anabolic or lipid metabolism, little is known about the impact of Nrf2 or MI on the biochemical metabolism in the liver. Because the liver is a center for metabolism, metabolomic landscapes were determined in a model of chronic oxidative stress by Nrf2 knockout or acute oxidative stress by induction of MI via left anterior descending coronary artery ligation. 1353 compounds were detected with a quality control coeffcient variation value <20% using LC-MS/MS based non-targeted metabolomics. Differences in the baseline metabolic profiles of male versus female lead to comparison of Nrf2 knockout or MI in a sex specific manner. In male wild type mice, the liver responded to MI by elevating several carnitine derivatives, including linoleoyl carnitine, palmitoyl carnitine, and (11Z, 14Z)-eicosadienoyl carnitine. However, none of these changes were observed in female wild type mice. Either male or female Nrf2 knockout mice failed to respond to MI by elevating carnitines. These acylcarnitine increases were confirmed with a non-targeted lipidomics analysis. The elevated acylcarnitine levels correlate with an increase in carnitine palmitoyl transferase 1, CPT1, the enzyme responsible for the conjugation of carnitine and long-chain fatty acids. After this conjugation, acylcarnitines are transported into the mitochondria via carnitine-acylcarnitine translocase. Once inside the mitochondria, the carnitine moiety is removed via CPT2 and the long-chain fatty acid can be used for beta-oxidation to produce ATP. This data suggest that male mice are responding to MI by altering energy metabolism and increasing carnitines to compensate for energy production. Nrf2 appears to play a role in such metabolic reprogramming.

The research programs under the direction of Dr. Qin M. Chen have been supported by NIH R01 GM125212, R01 GM126165, Holsclaw Endowment, the University of Arizona College of Pharmacy start-up fund, and NIEHS T32 ES007091.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
The effect of baroreflex-induced sympathetic suppression on renal arterial impedance in rats
Authors: Fukuda Yukiko , Kawada Toru , Kataoka Yasuyuki , Peterson Jon , Saku Keita , Alexander Joe , Sunagawa Kenji
Published: May 2024

Objective: We examined the effect of baroreflex on renal arterial impedance (ZRA) to gain insights into renal hemodynamics and local autoregulation. Methods: This study involved male Wistar-Kyoto rats (n = 6). We measured renal arterial pressure (PRA) and renal arterial flow (FRA). For high-resolution renal arterial impedance (ZRA) over the frequency range of 0.1-70 Hz, random pacing was employed. We isolated the bilateral carotid sinus baroreceptor regions and utilized a servo pump to control carotid sinus pressure (CSP) either at 60 mmHg or 140 mmHg. We controlled mean arterial pressure (AP) at 100 mmHg (AP-fix) or allowed to vary in response to changes in CSP (AP-variable). A three‐element Windkessel (3-WK) model was used to quantify ZRA (R1: proximal resistance, R2: distal resistance, and C: renal compliance). Results: With AP-fix, an increase of CSP from 60 mmHg to 140 mmHg did not change mean PRA (99.85 ± 0.16 vs. 98.00 ± 1.22 mmHg, P = ns) or mean FRA (8.73 ± 0.41 vs. 8.10 ± 0.38 min/mL, Δ = −7%, P = ns). This rise of CSP did not significantly affect R1 (0.74 ± 0.11 vs. 0.61 ± 0.12 mmHg·min/mL, P = ns) or R2 (8.13 ± 1.08 vs. 8.79 ± 0.85 mmHg·min/mL, P = ns), but it did increase C by 20% (4.05 ± 0.47 vs. 4.88 ± 0.35 (×10−5) mL/mmHg, P < 0.05). With AP-variable, elevating CSP from 60 mmHg to 140 mmHg significantly lowered mean PRA by 38% (105.42 ± 2.84 vs. 65.15 ± 4.87 mmHg, P < 0.01), but did not change mean FRA (9.00 ± 0.48 vs. 7.92 ± 0.66 min/mL, Δ = −12%, P = ns). Changes in CSP did not affect R1 (0.77 ± 0.12 vs. 1.23 ± 0.24 mmHg·min/mL, P = ns), but they did reduce R2 by 41% (8.01 ± 1.08 vs. 4.76 ± 0.79 mmHg·min/mL, P < 0.01) and increase C almost five-fold (3.79 ± 0.36 vs. 22.16 ± 6.91 (×10−5) mL/mmHg, P < 0.05). Conclusion: The minor change in FRA (−12%) despite a 38% drop in PRA suggests the presence of local autoregulation to buffer changes in renal blood flow. The primary effect of renal hemodynamic regulation on ZRA was found in R2. When AP was allowed to vary in response to changes in CSP, increasing CSP, the baroreflex-induced sympathetic suppression decreased R2. However, when AP was held constant at 100 mmHg, the reduction in R2 was not observed, even with baroreflex activation resulting from changes in CSP. Hence, the local renal autoregulation may counteract the baroreflex, maintaining renal blood flow unchanged. Such a mechanism serves to protect the glomeruli from exogenously induced high mean AP.

NTT Research, Inc.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Glycoprotein VI Platelet Receptor Blockade Attenuates Progression of Established Abdominal Aortic Aneurysms in Murine Models
Authors: Brunner Seth , Benson Tyler , Spuzzillo Anthony , Wadding-Lee Caris , Coughlin Taylor , Cameron Scott , Owens Phillip
Published: May 2024

Objective: Abdominal aortic aneurysms (AAA) frequently feature the formation of a nonocclusive intraluminal thrombus (ILT) along the site of aortic dilation. Platelets are known to maintain hemostasis and propagate thrombosis through several redundant activation mechanisms, yet the role of platelet activation in the pathogenesis of AAA associated ILT is still poorly understood. Thus, we sought to investigate how platelet activation via the glycoprotein VI receptor pathway impacts the pathogenesis of AAA. Methods and Results: RNA sequencing was performed on age-matched control human aortic tissue, AAA aortic tissue, and AAA ILT. Platelet transcripts comprised 25% of significantly enriched genes in the comparison of AAA thrombus to AAA tissue and control aortic wall, with GPVI increased by 9.1 Log2-FC (P = 3.21E−08). Circulating GPVI was significantly elevated in platelets isolated from AAA patients versus age-matched controls. Soluble GPVI (sGPVI—indicator of platelet activation), was significantly increased in the plasma of patients with fast-growing AAAs compared to slow-growing AAAs and healthy control subjects. To determine if GPVI blockade was protective from AAA progression, mice underwent either the angiotensin II (AngII) infusion or the topical elastase models of aneurysm formation. Following model initiation, aortic diameter was monitored by weekly ultrasounds. After two weeks, mice which developed an aneurysm (defined as an aortic diameter of >1.2mm) were randomized into control (IgG—50μg) or treatment (JAQ1—50μg, monoclonal GPVI antibody) groups. As expected, platelets isolated from JAQ1 treated mice did not activate in response to the GPVI specific agonist convulxin. Furthermore, JAQ1 treatment attenuated aneurysm progression, increased type I collagen deposition, attenuated macrophage accumulation, and increased survival in both murine AAA models versus IgG control treated mice. Conclusions: Platelets play a critical role in AAA pathophysiology and specific blockade of the GPVI-mediated activation pathway attenuates progression of established aneurysms in two independent murine models. Thus, our work demonstrates that specific targeting of GPVI to blunt platelet activation in AAA could be a potential therapeutic for a pathology with no current pharmacological treatments.

R01HL147171-04 and R01HL158801-02.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
The SNX17-Retriever endosomal recycling pathway is a key regulator of synaptic function and plasticity in hippocampal neurons
Authors: Chavis Garrett , Rivero-Rios Pilar , Tsukahara Takao , Uygun Tunahan , Iwase Shigeki , Weisman Lois , Sutton Michael
Published: May 2024

The insertion and removal of integral membrane proteins is a key mechanism for the regulation of synaptic function. Once surface proteins are internalized, they can either be routed to lysosomes for degradation or can be recycled back to the cell surface. Two recycling protein complexes - the SNX27-Retromer complex and the recently discovered SNX17-Retriever complex - are the main drivers in recycling internalized cargoes in non-neuronal cells. In neurons, the SNX27-Retromer pathway has been shown to regulate surface expression of AMPA-type glutamate receptors (AMPARs) during long-term potentiation (LTP), but almost nothing is known regarding the role of the SNX17-Retriever pathway at synapses. Here, using cultured hippocampal neurons, we demonstrate that the SNX17-Retriever pathway localizes to both synaptic and extra-synaptic sites and that RNAi-mediated disruption of this pathway leads to the functional and structural loss of excitatory synapses. Moreover, we find that synaptic stimulation leads to the recruitment of SNX17 to synaptic sites in a manner that depends on Ca2+ influx through NMDARs, activation of CaMKII, and Retriever complex binding. Knockdown of either SNX17 or the Retriever subunit DSCR3 prevents structural plasticity of dendritic spines during LTP. Finally, this loss of structural plasticity is associated with altered traffcking of the cell adhesion molecule β1 Integrin, which is a SNX17 cargo in non-neuronal cells and as we show, in neurons as well. Additionally, SNX17-Retriever is shown to not play a role in AMPAR recycling. Preliminary studies suggest that SNX27 and SNX17 sort distinct cargos in neurons, suggesting that these two recycling pathways each play important, but unique, roles at synaptic sites.

National Institute of Neurological Disorders and Stroke (NINDS) of the National Institutes of Health (NIH) under award numbers R01-NS129198 to L.S. Weisman and M.A. Sutton, R01-NS099340 and R01- NS064015 to L.S. Weisman, R01-NS097498 to M.A. Sutton, and R21-NS125449, and R01-NS116008 to S. Iwase, by the National Institute of Mental Health (NIMH) of the NIH under award number R21-MH127485 to S. Iwase.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Normal Skeletal Muscle Growth and Function Require Insulin Receptors Expressed by Cholinergic Motor Neurons
Authors: Hyun Uisu , Kim Youngjun , Sohn Jong-Woo
Published: May 2024

It is well known that insulin stimulates skeletal muscle growth. However, it is currently unknown how insulin does so since it was previously shown that insulin receptors expressed by skeletal muscles are dispensable in this regard. In this study, we focused on insulin receptors expressed by the cholinergic motor neurons and generated conditional knockout mice which lack insulin receptors specifically in the cholinergic neurons. We found that insulin activates cholinergic motor neurons and that insulin receptors expressed by the cholinergic neurons are required for normal growth of skeletal muscle. We also noted that the conditional knockout mice have underdeveloped neuromuscular junction and compromised skeletal muscle function. Together, our study suggests that insulin stimulates and activates cholinergic motor neurons to promote normal skeletal muscle growth and function.

This work was supported by the National Research Foundation of Korea (NRF-2022R1A2C3005613 to Jong-Woo Sohn) funded by the Korean Ministry of Science and ICT.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Cyclic strain promotes MCP-1 expression in Dahl Salt Sensitive (SS) rat vascular smooth muscle cells (VSMCs) through the TGF-β pathway
Authors: Feng Conrad , Xing Dongqi , Ying Wei-zhong , Guan Zhengrong , Sanders Paul
Published: May 2024

Prior studies have suggested a role for TGF-β in the generation of hypertension in SS rats. We have shown that production of MCP-1 (CCL-2) and TGF-β1 increase in the vasculature of hypertensive SS rats. This study aims to explore novel mechanisms of hypertension development. We hypothesize that TGF-β1 regulated the production of MCP-1 by VSMCs in the setting of cyclic strain. Primary cultures of SS aortic VSMCs in early (<6) passages were grown in standard fashion in Dulbecco’s Modified Eagle’s Medium supplemented with 10% fetal bovine serum. Cultured cells were identified as smooth muscle cells by their characteristic morphology and positive immunostaining for α-smooth muscle actin. In the first study, VSMCs were treated with recombinant active TGF-β1 (1 ng/mL and 10 ng/mL) for 6 h, then harvested for MCP-1 mRNA quantification by SYBR green qPCR. Medium was also collected to determine MCP-1 levels using ELISA. TGF-β1 increased MCP-1 mRNA expression by 2.0- and 3.1-fold in VSMC incubated in medium containing 1 ng/mL and 10 ng/mL of TGF-β1, respectively. In a second series of studies, VSMCs were seeded onto 6-well BioFlex plates. Some cells were pre-treated with 10 μmol/mL of an ALK4/5 inhibitor. Cyclic strain, an in vitro model of hypertension, was performed using the FlexCell 6000 and a standardized regimen (8 h, 15% elongation @ 1 Hz). Cells and medium were then harvested for mRNA analyses and determination of MCP-1 levels. When compared with expression by VSMCs maintained under static condition, cyclic strain increased (p<0.05) MCP-1 mRNA expression 4.2-fold and TGF-β1 mRNA 1.93-fold. Cyclic strain also increased (p<0.01) MCP-1 protein in the medium (static condition vs cyclic strain, 112.6 ± 7.1 pg/mL vs 222.5 ± 6.5 pg/mL, n=6). Pre-treatment of VSMC with the ALK4/5 inhibitor reduced mRNA expression of MCP-1 mediated by cyclic strain (Cyclic strain vs Cyclic strain + AKL4/5 inhibitor, 4.5 ± 1.06 vs 2.88 ± 0.47, n=6, P < 0.01). Thus, cyclic strain promotes MCP-1 production by VSMCs through the TGF-β pathway. The data support the need for further study of this interaction as well as a potential role in arterial hypertension in this rodent model.

Department of Veterans Affairs Basic Sciences R&D (BSRD) Service (1 I01 BX005640) National Institutes of Health (P30 DK079337).

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
RBX1-CRLs Promote Perinatal Heart Development by Regulating Hippo-YAP Signaling
Authors: Zambrano-Carrasco Josue , Wang Wenjuan , Ayala Juan , Sibley John , Carruth Jessica , Jiao Kai , Li Jie
Published: May 2024

Background: During development, the heart is the first organ to form, ensuring the pumping of blood through the body. Defects in cardiac morphogenesis can lead to congenital heart diseases (CHD) or predispose the heart to cardiomyopathies in adult life. The molecular mechanisms underlying this process remain incompletely understood. Cullin-RING E3 ubiquitin ligases (CRLs) are multi-subunit complexes critical to maintaining protein homeostasis by targeting diverse protein substrates for ubiquitination and subsequent degradation. In CRLs, RBX1 serves as the catalytic subunit that promotes the transfer of ubiquitin to the target protein. Germline ablation of RBX1 in worms, flies, and mice caused embryonic lethality. Deletion of RBX1 in zebrafish resulted in cardiac malformation and dysfunction, which was rescued by endothelial, but not myocardial, RBX1 overexpression. However, the cardiomyocyte-autonomous role of RBX1 in the heart in vertebrates is unknown. Therefore, we hypothesize that cardiomyocyte RBX1 is indispensable for cardiac development. Methods and Results: We generated a cardiomyocyte-specific RBX1 knockout (RBX1CKO) mouse model via αMHCCre. RBX1-deficient mouse embryos were initially morphologically indistinguishable from the littermate controls at E14.5, but began to show peripheral edema and hemorrhage at E16.5, and eventually died around E18.5. Histological analysis of RBX1CKO hearts revealed severe myocardial hypoplasia and bi-ventricular non-compaction by E14.5. Bulk RNA sequencing and proteomic analyses of RBX1CKO hearts identified perturbations in glycolytic to oxidative transition and dysregulation of sarcomeric proteins. EdU incorporation assay showed a significant reduction in cardiomyocyte proliferation in E14.5 RBX1-deficient hearts, accompanied by the impaired nuclear translocation of YAP, a co-transcriptional factor essential for cardiomyocyte proliferation and maturation. Mechanistically, RBX1 deficiency destabilized multiple CRLs and resulted in the accumulation of Hippo kinases and adaptor proteins such as SAV1, LATS1/2, and MOB1, leading to the elevated phosphorylation and inactivation of YAP. We further demonstrated that loss of RBX1 inhibited the degradation of the Hippo adaptor MOB1, likely due to suppressed ubiquitination. Conclusion: Our study identifies RBX1 as an essential regulator of ventricular maturation and found that RBX1-mediated proteolysis of Hippo kinases serves as a critical checkpoint to ensure YAP activation and, hence, cardiomyocyte proliferation and maturation during cardiac development.

AHA Predoctoral Fellowship, American Heart Association, 23PRE1012641.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Innovative Approach to Dam Deformation Analysis: Integration of VMD, Fractal Theory, and WOA‐DELM
Authors: Ou Bin , Zhang Caiyi , Xu Bo , Fu Shuyan , Liu Zhenyu , Wang Kui
Published: May 2024

This paper introduces a novel and comprehensive model for the analysis of dam deformation trends, integrating the variational mode decomposition (VMD) method, fractal theory, and the whale optimization algorithm (WOA) to refine the deep extreme learning machine (DELM) model. This integration allows for a meticulous denoising process through VMD, effectively isolating pertinent signal characteristics from noise and measurement interference. Following this, fractal theory is utilized to conduct an in‐depth qualitative analysis of the denoised data, capturing intricate patterns within the deformation trends. The model further evolves with the application of WOA to optimize the DELM model, thereby facilitating an integrated approach that merges qualitative insights with quantitative analysis. The efficacy of this advanced model is demonstrated through a case study, highlighting its capability to deliver accurate and reliable predictions that are in harmony with practical engineering scenarios. This research not only offers a robust framework for analyzing dam deformation trends but also sets a new standard in the field, providing a new solution for assessing structural integrity in hydrological engineering.