bluuebunny/crossref_metadata_2025 huggingface dataset:
Metformin Blunts Bed Rest-induced Skeletal Muscle Ceramide Accumulation in Older Adults
Authors: M. Yee Elena , M.M.P. de Hart Naomi , Mckenzie Alec , J. Petrocelli Jonathan , Kaput Katie , Wahl Matthew , Supiano Mark
Published: May 2024

Skeletal muscle insulin resistance is an undesirable outcome during periods of physical inactivity in older adults, which can lead to a variety of metabolic diseases. Insulin sensitive tissue (e.g., liver, and skeletal muscle) derived ceramides are well known to promote insulin resistance. Evidence suggests that metformin can regulate tissue ceramide accumulation. Therefore, we hypothesized that metformin treatment during a short-term period of bed rest in male and female older adults would reduce skeletal muscle ceramide accumulation and prevent insulin resistance. Our study design consisted of older adults (66 ± 4.5 y/o placebo, n=10; 71.7 ± 5.1 y/o metformin, n=10) who were subjected to 5 days of bed rest. Participants were randomly assigned to placebo or metformin treatment groups. Drug or placebo treatments started two weeks prior to bed rest and continued throughout the 5 days of bed rest. Prior to and after bed rest, participants underwent a euglycemic-hyperinsulinemic clamp. Muscle biopsies (from the vastus lateralis) were taken prior to and after each clamp both before and after bed rest. We found that insulin-stimulated muscle ceramides were increased after bed rest but were blunted in older adults who took metformin. In addition, muscle insulin resistance correlated with the increase in ceramides. We conclude that metformin was effective to reduce ceramide accumulation in muscle during a period of bed rest in older adults.

R21AG064576 awarded to M.J.D.

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.
Drp1 Controls Complex II Assembly and Skeletal Muscle Metabolism by Sdhaf2 Action on Mitochondria
Authors: Zhou Zhenqi , Ma Alice , Moore Timothy , Tran Peter , Shirihai Orian , Hevener Andrea L
Published: May 2024

The Dynamin-related GTPase, Drp1 (encoded by Dnm1l) plays a central role in mitochondrial fission and is requisite for numerous cellular processes however its role in muscle metabolism remains unclear. Herein, we show that among human tissues, the highest number of significant gene correlations with DNM1L are in skeletal muscle. Knockdown of Drp1 (Drp1-KD) promoted mitochondrial hyperfusion in the muscle of male mice. Reduced fatty acid oxidation and impaired insulin action along with increased muscle succinate was observed in Drp1-KD muscle. Muscle Drp1-KD reduced Complex II assembly and activity as a consequence of diminished mitochondrial translocation of succinate dehydrogenase assembly factor 2 (Sdhaf2). Restoration of Sdhaf2 normalized Complex II activity, lipid oxidation, and insulin action in Drp1-KD myocytes. Drp1 is critical in maintaining mitochondrial Complex II assembly, lipid oxidation, and glucose homeostasis, suggesting a mechanistic link between mitochondrial morphology and skeletal muscle metabolism, which is clinically relevant in combatting metabolic diseases.

P30DK063491, DK125354.

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.
Effect of N-Acetyl-Carnosine on Body Weight and Composition
Authors: Milam Norah , Miranda Edwin , Funai katsuhiko
Published: May 2024

With a globally aging population, the need for treatments that address age related comorbidities are more relevant than ever. Previous research done in our lab has shown that treatment of mice with the compound N-Acetyl-Carnosine (N-Ac-Carn) could partially prevent protein damage caused by lipid peroxidation, and subsequent muscle atrophy and weakness in a mouse-model of inactivity. N-Ac-Carn is endogenously produced, safe, and affordable making it a potentially promising strategy for age-related functional decline. Our current pre-clinical trial aims to comprehensively determine the effcacy of N-Ac-Carn treatment in preventing age-related functional decline. To this end, 18-month-old mice were treated with either normal water (CON) or water supplemented with 80mM N-Ac-Carn (N-Ac-Carn) for 6 months. Targeted metabolomics verified that this treatment enriched all tissues with N-Ac-Carn. Mice treated with N-Ac-Carn maintained higher body weights longer than CON (Interaction: p=0.022). This effect was driven specifically by higher fat mass over time (p=0.016) in female mice. These changes in the N Acetyl Carnosine mice were not explained by an increase in overall food consumption, which remained similar across both groups. Metabolic cage analysis revealed lower VO2 in N-Ac-Carn mice (Group: p=0.002) although this effect was observed in both male and female mice (Interaction: p=0.878). Despite higher fat mass, IPGTT revealed equivocal glucose tolerance in CON and N-Ac-Carn mice. Therefore, this preserved fat mass with aging is not detrimental to metabolic regulation and may be protective against developing other symptoms of frailty. Future analysis will pursue the mechanisms of preserved adipose tissue mass with N-Ac-Carn treatment and if this phenotype is associated with improved health span.

R01AG074535-03.

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.
Cystic fibrosis rescued using a reprogrammed porosome secretory machinery
Authors: Cho Won Jin
Published: May 2024

Cystic fibrosis (CF) is a genetic disorder resulting in the secretion of highly viscous mucus in the airways, leading to lung infection, respiratory failure, morbidity and mortality. CF is attributed to mutation in the CF Transmembrane Conductance Regulator (CFTR) gene that codes for a chloride transporting channel at the cell plasma membrane. More than 2,000 mutations in the CF gene have been identified; however, the ΔF508 CFTR is the most common, accounting for approximately 70% of all CFTR mutations. Our earlier studies demonstrate the CFTR protein to be among the nearly 30 proteins constituting the porosome secretory machinery at the plasma membrane in human airway epithelial mucous-secreting cells. Our recent studies show that stimulated human airway epithelial cells pre-exposed to CFTR inhibitors result in loss of mucus secretion, suggesting the involvement of CFTR in porosome-mediated mucus secretion. To further test the hypothesis that CFTR is involved in porosome-mediated mucus secretion in the human airways, and to develop a therapeutic approach to overcome this defect in ΔF508 CFTR human bronchial epithelial cells, the current study was undertaken. Mass spectrometry and Western Blot analysis of porosomes isolated from WT-CFTR Human Bronchial Epithelial (HBE) Cells and ΔF508-CFTR CF HBE cells, demonstrate a varying loss or gain of several porosome proteins, including undetectable levels of the Ras GTPase activating like-protein IQGAP1 in the ΔF508-CFTR CF cells. This suggested that mutation in porosome-associated CFTR protein additionally affects other proteins within the porosome secretory machinery, negatively impacting mucus secretion. Therefore, to ameliorate defects in mucus secretion in CF, the reconstitution of functional porosomes obtained from WT-CFTR HBE cells into the plasma membrane of ΔF508-CFTR mutant cells was performed. Results from the study demonstrate that porosome reconstitution rescues mucus secretion approximately two- to four-fold more effectively than the currently available CF drugs including TRIKAFTA.

Acknowledgements: Work presented in this article was supported by the Viron Molecular Medicine Institute and Porosome Therapeutics, Inc., Boston, MA. Competing Financial Interest: This work is patent protected by Porosome Therapeutics, Inc. The authors hold shares in the company.

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.
Enhancing Learning Opportunities in Laboratory Science Using Virtual Reality Lessons: A Use Case
Authors: Zubek John , Shine Sarah , Warznie Julia , Medina Jenna
Published: May 2024

Animal dissections are a common approach to teaching anatomy and physiology, but they are costly, pose safety risks, and raise ethical concerns. Alternatives like computer simulations and synthetic specimens have been explored, but they lack the realism of live dissections. Virtual reality (VR) technology provides a promising solution by immersing learners in a virtual environment that closely mimics real-life dissections and allows for skill development and feedback. VR also removes ethical and emotional concerns associated with dissections and enhances learning opportunities. To explore the effectiveness of VR in anatomy and physiology education, we conducted a detailed survey of 48 students in an undergraduate physiology laboratory course. The survey, administered before and after students performed both a VR frog dissection and an in-person frog dissection, was designed to gauge their perceptions, preferences, and learning experiences with both methods. Results indicate that while no participants considered VR a perfect substitute, a majority (80%) still viewed animal dissections as an essential part of science laboratory courses. Interestingly, 43% of participants expressed a stronger preference for live dissections post-experiment, citing greater excitement and perceived informativeness. In contrast, 25% favored VR or alternative methods, highlighting increased comfort and reduced discomfort. A recurring theme was VR's role as a preparatory or alternative tool for those hesitant towards live dissection. This study underscores VR's potential in addressing traditional dissection methods' limitations and emphasizes the need for further research into VR's effectiveness in anatomy and physiology education. We aim to foster dialogue on the use of alternative technologies in enhancing learning opportunities within laboratory and clinical sciences.

This project was funded by the Department of Physiology at Michigan State University.

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.
Specific deletion of FHA domain containing SLMAP isoform in mice impacts embryonic development without affecting Hippo signaling. AP Dias, T Rehmani, M Salih BS Tuana
Authors: Dias Ana , Rehmani Taha , Salih Maysoon , Tuana Balwant
Published: May 2024

The tail-anchored membrane protein SLMAP3 has been proposed to negatively regulate Hippo signaling and impact cell proliferation. Proteomics have defined SLMAP in complex with STRIPAK a multiprotein interactome consisting of Germinal center kinases and PP2A phosphatase. Data also suggests that the N-terminal FHA domain of SLMAP3 can bind Hippo kinase (MST 1/2) while it‘s coiled-coil regions can integrate PP2A phosphatase to modulate the downstream phosphorylation of YAP/TAZ for cytoplasmic retention. Nuclear YAP/TAZ serve as coactivators of TEAD mediated transcription of genes involved in cell proliferation and organogenesis. The physiological importance of SLMAP3 and it‘s in vivo function in regulating Hippo and organ development remains to be determined. We report that mice with specific deletion of SLMAP3 isoform were embryonic lethal where most organs including muscle, brain, spinal cord, kidney, lungs, intestines, cartilage and bone exhibited severe developmental deficits. The SLMAP3 deficient embryos were ~30% smaller (p<0.05) with small organs compared to wild types. The analysis of Hippo components MST1/2 and YAP/TAZ indicated no changes in their phosphorylation status in embryos or tissue such as muscle and the neural tube due to the loss of SLMAP3. RNA-Seq of whole embryos showed no significant changes to downstream targets of Hippo signaling in SLMAP3-KO. In addition, SLMAP3 loss had no obvious effect on cell proliferation assessed with Ki-67/pH3 staining in embryogenesis. Mouse primary embryonic fibroblasts (MEFs) isolated from embryos deficient in SLMAP3 had no changes in YAP and MST1/2 phosphorylation or proliferation while RNA-seq analysis indicated no changes in TEAD regulated gene activity. Further, phospho-proteomics of MEF lysates revealed no changes in Hippo signaling in SLMAP3 loss, nor in pathways associated with cell proliferation or death. Similarly, knockout of SLMAP3 in myoblast displayed no changes in Hippo signaling or proliferation capacity. These data indicate that SLMAP3 is critically important for embryonic development through unique mechanisms and do not implicate the involvement of Hippo signaling.

Supported by CIHR.

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.
DNA methylation by DNMT3a drives endothelial inflammation and death during acute lung injury
Authors: Akhter Md Zahid , BR Vijay Avin , Joshi Jagdish Chandra , Mehta Dolly
Published: May 2024

Vascular endothelium, the inner most lining of all blood vessels, controls the transport of nutrients, protein, water, and leukocytes across the vessel wall and thereby maintains lung tissue and fluid homeostasis. Damage to endothelial integrity caused by mediagenic, inflammatory, or toxic agents results in pulmonary edema, inflammation, organ failure, and high lethality. A key pathogenic characteristic of vascular injury involves an excessive loss of endothelial cells (EC) accompanied by the generation of inflammatory cytokines. Genome-wide analyses of DNA methylation, the most enduring epigenetic modification of DNA, and its impact on EC transcriptomes and cellular functions, still lack comprehensive understanding. We demonstrate that lipopolysaccharide (LPS) elevated DNA methylation in EC within the lungs, primarily through a mechanism dependent on DNA methyltransferase 3a (DNMT 3a). Mice with endothelial cell-specific deletion of DNMT3a ( EC-DNMT3a−/−) promptly recovered from lung injury, attributed to a reduction of EC death. Furthermore, we observed that the deletion of DNMT3a in EC led to an increase in the expression of the apoptosis inhibitor B-cell lymphoma 2 (BCL2). Collectively, the data implies that inhibiting DNMT3a activity plays a crucial role in reshaping the EC methylome and promoting BCL-2 activity. This, in turn, facilitates the generation of reparative EC and contributes to the resolution of acute lung injury (ALI). These findings offer insights into potential targets for preventing ALI.

American Heart Association (AHA) Postdoctoral Fellowship (19POST34450241).

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.
Interactions Between Carotid Arterial Stiffness, Amplitude of Cerebral Blood Flow Oscillations, and Cerebral Tissue Oxygenation During Simulated Hemorrhage in Humans
Authors: Hudson Lindsey , Davis K. Austin , Anderson Garen , Rosenberg Alexander , McKeefer Haley , Bird Jordan , Pentz Brandon
Published: May 2024

Introduction: Inducing 0.1 Hz (10-s cycle) oscillations in cerebral blood flow attenuates the reduction in cerebral tissue oxygenation during simulated hemorrhage in humans. It is unknown, however, how stiffness of the cerebral feed arteries influences the magnitude of cerebral blood flow oscillations, and/or the protection of cerebral tissue oxygenation. When 0.1 Hz oscillations are induced during simulated hemorrhage, we hypothesize that: 1) arterial stiffness of the internal carotid artery (ICA) will increase from rest; 2) the amplitude of 0.1 Hz oscillations in cerebral blood flow will be higher in individuals with stiffer arteries, and; 3) the reduction in cerebral tissue oxygenation will be smaller with higher amplitude of cerebral blood flow oscillations. Methods: 8 healthy human participants (age: 30.1±7.6 y) underwent a 10-min hypovolemic oscillatory lower body negative pressure (OLBNP) protocol, where chamber pressure oscillated every 5-s between -30 mmHg and -90 mmHg (i.e., 0.1 Hz). ICA beta stiffness index was calculated from measurements of ICA diameter (via ultrasound imaging), and arterial pressure (via finger photoplethysmography). Middle cerebral artery velocity (MCAv) was measured using transcranial doppler ultrasound, and cerebral tissue oxygenation (ScO2) was measured with near infrared spectroscopy. Fast Fourier transformation was used to quantify oscillations in mean MCAv at ~0.1 Hz. Results: While Mean MCAv 0.1 Hz oscillations increased from baseline to OLBNP (N=8, 34.0±33.9 (cm/s)2 vs. 104.7±58.1 (cm/s)2, p=0.01), ICA beta stiffness did not increase (N=5, 6.1±0.7 au vs. 8.2±2.7 au, p=0.21). There was no relationship between baseline ICA beta stiffness and the percent change in mean MCAv 0.1 Hz oscillations (N=5; r=0.44, p=0.46). ScO2 decreased from baseline to OLBNP (N=8, 66.5±2.9 % vs. 64.8±2.9 %, p=0.03), but there was also no relationship between the percent change in mean MCAv 0.1 Hz oscillations and the decrease in ScO2 (r=0.28, p=0.50). Conclusions: Based on these data, 0.1 Hz OLBNP does not affect ICA stiffness, and there is no relationship between ICA stiffness, amplitude of induced 0.1 Hz cerebral blood flow oscillations, and the reduction in cerebral tissue oxygenation during simulated hemorrhage. However, as this analysis was performed retrospectively, and arterial stiffness was not initially an outcome measure, there was limited data available for analysis. This limitation will be addressed in a project currently in progress in our laboratory.

American Heart Association Grant in Aid.

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.
Phosphatidylserine supplementation as a potential strategy to improve endothelial function in type 2 diabetes
Authors: Augenreich Marc , Ramirez-Perez Francisco I. , Imkaew Natnicha , Ferreira-Santos Larissa , Power Gavin , Martinez-Lemus Luis A. , Padilla Jaume
Published: May 2024

Endothelial dysfunction represents a causal factor in the pathogenesis of cardiovascular disease associated with type 2 diabetes (T2D), including hypertension. Previous work has revealed that endothelial mechanosensing structures are degraded in T2D, resulting in impaired shear stress mechanotransduction and decreased flow-mediated dilation (FMD). One well-known mechanosensor that is susceptible to cleavage is glypican-1, a prominent proteoglycan member of the endothelial glycocalyx. In this regard, recent evidence from a proteomic analysis suggests that glypican-1 is a substrate of the proinflammatory enzyme ADAM17 (a disintegrin and metalloproteinase-17), which is elevated in the vasculature of T2D. Recent work has revealed that exogenous phosphatidylserine (PS) inhibits in vitro ADAM17 sheddase activity, which may aid in retaining the membrane-bound glypican-1. Therefore, we hypothesized that oral administration of PS in diabetic mice (db/db) would enhance shear stress mechanotransduction, as assessed by FMD, and that this would be accompanied by greater presence of glypican-1 on the endothelial surface. We further hypothesized that PS would reduce blood pressure. We tested this hypothesis in ~10-week-old db/db male mice that were randomized to receive a daily peanut butter pellet as vehicle control or the pellet mixed with soy-derived PS (200 mg/kg/day) for 28 days. A third group of untreated age-matched wild-type C57BL/6J male mice served as healthy controls. Excised mesenteric arteries were used for assessment of FMD using pressure myography, while femoral arteries were used for determining presence of glypican-1 content on the endothelial surface using confocal microscopy. Blood pressure was assessed using the tail-cuff method. All reported differences are significant at p<0.05. Compared with wild-types, untreated db/db mice had impaired FMD, reduced presence of endothelial glypican-1, and increased blood pressure. Notably, these effects were not observed in db/db mice treated with PS. These findings suggest that oral PS may be effective at improving indices of endothelial dysfunction in T2D, an effect likely mediated by the retention of endothelial mechanosensor glypican-1 via reduced ADAM17 sheddase activity.

No support to disclose.

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.
HSP47 complements cholesterol synthesis-independent HMGCoA-reductase pathway-mediated fibroblast bioenergetics
Authors: Salem Salsabeel , Benjamin Ivor , Ross Gracious , Vodanovic-Jankovic Sanja
Published: May 2024

Fibrosis, characterized by excessive extracellular matrix (ECM) components deposition, is a common pathological process underlying numerous chronic diseases. Differentiating fibroblasts into myofibroblasts leads to the deposition of fibrous proteins like collagen in the ECM. Heat shock protein 47 (HSP47) is a molecular chaperone protein that assists in the folding of collagen. Recent studies show that inhibition of cholesterol synthesis-independent HMGCoA-reductase pathway enzyme geranylgeranyl pyrophosphate synthase 1 (GGPS1) decreases fibroblast differentiation and its bioenergetics. However, the role of HSP47 in this pathway is unknown, although recent observations show that HSP47 is decreased when GGPS1 is inhibited. Hence, we tested the hypothesis that HSP47 promotes cellular respiration in myofibroblasts. Seahorse assays were performed on different fibroblasts/myofibroblasts repeatedly and the oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) were measured in the presence and absence of HSP47 inhibitor (HY124817). Complex V of the electron transport chain was measured by immunoblotting ATP-5A. HY124817 tends to decrease the OCR, basal respiration rate, ATP-linked, and spare respiratory capacity. Co-incubation with HY124817 and digeranyl bisphosphonate (DGBP), an inhibitor of GGPS1, significantly (P = 0.043) inhibited further the ATP-linked OCR compared to the TGF group. Immunoblotting showed that Complex V did not change significantly across treatments. These results suggest that HSP47 is involved in fibroblast bioenergetics related to ATP-linked OCR in both differentiated myofibroblasts and normal fibroblasts. Inhibition of HSP47 complements the decrease in myofibroblast cellular respiration caused by the GGPS1 inhibition. This finding is novel in that HSP47 plays a role in fibroblast bioenergetics regulated by the cholesterol synthesis-independent HMGCoA-reductase pathway. Further research is necessary to identify what HSP47 targets and regulatory elements involved in this process. This would provide more insight into the mechanisms that underlie critical fibrosis conditions like myocardial fibrosis and potential therapeutics.

This experience was supported by the Medical College of Wisconsin's Advancing Student Potential for Inclusion with Research Experiences (ASPIRE) program. The program is funded by a federal grant from the National Heart, Lung, and Blood Institute.

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.
Normobaric Hyperoxia Treatment after Mid-cervical Contusion Injury in Rats
Authors: Deegan Kyle M. , Rana Sabhya , Martinez Robert , gonzalez Isabelle , Thakre Prajwal , Fuller David
Published: May 2024

Severe hypoxia at or near the site of spinal cord injury (SCI) contributes to necrosis and secondary tissue damage. Prior studies of O2 therapy after SCI have primarily used pressurized hyperoxic exposure ( i.e., hyperbaric oxygen). We tested the hypothesis that daily exposure to 100% O2, delivered at atmospheric pressure ( i.e., normobaric hyperoxia) could accelerate the recovery of inspiratory tidal volume after cervical SCI. Three groups of adult male Sprague Dawley rats received a 150 kdyn impact right lateral C4 cervical SCI. In group 1, normobaric hyperoxia (100% O2 at 1 atmosphere pressure, 2 hours) was initiated within 20 min of SCI and continued daily for 7 days. In group 2, the same normobaric hyperoxia paradigm was initiated on day 8 post-injury and continued until day 14. A third group received a sham treatment, consisting of exposure to normobaric normoxia (21% O2, 1 ATA) daily for 14 days. Whole-body plethysmography was used to examine breathing patterns before-, 1-, and 2-weeks post-SCI. All three groups lost and then gained body mass at similar rates over days 1-14 post-SCI. Mortality rates during the first week after SCI were 23% (5/22) in rats not exposed to hyperoxia, and 10% (1/10) in the daily hyperoxia group. Tidal volume (VT) and breathing rate were compared using 2-way repeated measures ANOVA. The breathing rate (br/min) was similar between groups at 1-week post-injury. We observed a trend (p=0.182) for reduced breathing rate at the 2-week time point in the week-1 hyperoxia group (69±18) compared to the week-2 hyperoxia group (89±21) and the normoxia group (83±17). Inspiratory VT (mL/breath) was elevated in the week-1 hyperoxia group (0.59±0.08) as compared to the week-2 hyperoxia (0.44±0.05) and normoxia groups (0.44±0.06) at 1-week post-SCI (p=0.002). When VT was normalized to body weight (mL/breath/kg) the same effect of O2 exposure was observed (p=0.001). The effect was transient, however, and at day 14 post-SCI VT was similar across the three experimental groups (p>0.50). We conclude that normobaric hyperoxia treatment during the first week after cervical SCI alters the pattern of breathing, and may have benefit to recovery.

R01HL153140-04.

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.
Divergent Effects of IL-18- and IL-18R-deficiency on Angiotensin II-induced Abdominal Aortic Aneurysm Formation
Authors: Sherriff Ashleigh-Georgia , Dinh Quynh Nhu , Thomas Jordyn , Figueiredo Galvao Hericka , Imyage Dona Malathi , Wickramasinghe Buddhila , Diep Henry
Published: May 2024

Currently, there are no pharmacological treatments for abdominal aortic aneurysms (AAA), and AAA rupture is fatal in ~90% of patients. Aortic inflammation is strongly correlated with the expansion of AAA and recently the NLRP3 inflammasome has been implicated in thedevelopment of AAA. Interleukin (IL)-18, an inflammasome-derived cytokine, exerts pro-inflammatory responses when bound to its cognate IL-18 receptor (IL-18Rα). The current project aimed to determine the effect of IL-18- and IL-18Rα-deficiency on the incidence of angiotensin (Ang) II-induced AAA. Ten-week-old male C57BL/6 (WT), IL-18-deficient ( Il18−/−) and IL-18Rα-deficient ( Il18r1−/−) mice were infused with Ang II (1.44 mg/kg/day, s.c.) for 28 days via osmotic minipump. Ang II-induced AAA incidence differed in all strains. While 52% of WT mice developed AAA (including premature deaths due to rupture), no AAAs were detected in Il18−/− mice (p<0.05, n=20-23). Strikingly, Il18r1−/− mice exhibited a higher incidence of AAA and associated mortality compared to WT mice(88%; p<0.05, n=23-25). Consistent with this finding, in vivo ultrasound imaging confirmed advanced dilation of the abdominal aorta at d7 after Ang II-treatment in Il18r1−/− mice cf. WT mice (1.49 ± 0.13 vs 1.15 ± 0.05 mm; p<0.05; n=23-25). Single cell RNA-sequencing of Ang II-infused mouse aorta revealed Il18r1 gene expression was limited to gamma-delta T cells, suggesting these cells may be driving IL-18 mediated AAA formation. In summary, IL-18-deficiency affords protection from AAA formation, while AAA incidence and severity were augmented in Il18r1−/− mice. Neutralisation of IL-18, but not IL-18Rα inhibition, may represent a novel therapeutic strategy to treat AAA.

NHMRC (GNT1143674).

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.
Coordinated Regulation of Myonuclear DNA Methylation, mRNA, and miRNA Levels Associates with Mitochondrial Function During an Acute Skeletal Muscle Growth Stimulus
Authors: Ismaeel Ahmed , Thomas Nicholas , Wen Yuan , von Walden Ferdinand , Murach Kevin
Published: May 2024

The central dogma of molecular biology dictates the general flow of molecular information from DNA that leads to a functional cellular outcome. In skeletal muscle fibers, the extent to which global myonuclear transcriptional alterations, accounting for epigenetic and post-transcriptional influences, contribute to an adaptive stress response is not clearly defined. In this investigation, we leveraged an integrated analysis of the myonucleus-specific DNA methylome and transcriptome, as well as myonuclear small RNA profiling to molecularly define the early phase of skeletal muscle fiber hypertrophy. The analysis of myonucleus-specific mature miRNA and other small RNA species provides new directions for exploring muscle adaptation and complemented the methylation and transcriptional information. Our multi-omics interrogation revealed a coordinated myonuclear molecular landscape during muscle loading that coincides with an acute and rapid reduction of oxidative metabolism. This response may favor a biosynthesis-oriented metabolic program that supports rapid hypertrophic growth.

Y.W. was supported by the National Institutes of Health (K99 AR081367) K.A.M. was supported by the National Institutes of Health (R00 AG063994 and R01 AG080047). F.v.W. was supported by the Swedish research council (2022-01392), AFM-Telethon (23137), SMDF, Åke Wiberg, Swedish Medical Association, and the Swedish Research Council for Sport Science (2022/10).

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.
Focal adhesion kinase (FAK) inhibition induces aquaporin 2 (AQP2) plasma membrane accumulation in renal epithelial cells by remodeling the actin cytoskeleton
Authors: Tchakal-Mesbahi Asma , He Jinzhao , Zhu Shuai , Yu Kevin , Huang Ming , Huang Huihui , Bouley Richard
Published: May 2024

The actin cytoskeleton is involved in the cellular traffcking of the AQP2 water channel in kidney collecting duct (CD) principal cells (PC): this plays an important role in water homeostasis. Focal adhesion kinase (FAK) is known to modulate the actin cytoskeleton through small GTPase-mediated pathways and we, therefore, investigated the potential role of FAK in AQP2 traffcking. We and others have previously shown that AQP2 constitutively traffcs and recycles independently of vasopressin (VP) and that this involves actin depolymerization/polymerization; therefore, FAK could regulate AQP2 traffcking through actin remodeling, bypassing the VP-V2R (cAMP/PKA) signaling pathway. To examine this, we used small molecule FAK inhibitors, VS-4718, GSK2256098 (GSK), or Defactinib-Hydrochloride (DH). We used immunofluorescence staining, a transferrin endocytosis assay ± cold block treatment, a fluorometric exocytosis assay using cells expressing secreted yellow fluorescent protein (ssYFP), a RhoA activity assay, and western blotting. Inhibiting FAK with 1mM VS-4718 for 30 min increased AQP2 membrane accumulation in LLCPK1 and IMCD kidney epithelial cells expressing AQP2. VS-4718 resulted in reduced clathrin-mediated endocytosis, as well as increased vesicle exocytosis, both mechanisms contributing to increased AQP2 membrane accumulation. This effect of FAK inhibition was independent of vasopressin/cAMP signaling and did not require phosphorylation of the Serine 256 residue of AQP2, since AQP2 membrane accumulation also occurred in cells expressing the constitutive dephosphorylation AQP2 S256A mutant. The FAK inhibitor VS-4718 promoted actin depolymerization (phalloidin staining assay) which would facilitate AQP2 vesicle exocytosis into the plasma membrane. We then examined the activity of the small GTPase, RhoA, whose activity increases actin polymerization and vesicle traffcking in the exocytic and endocytic pathways. We found that FAK inhibition by VS-4718 downregulated RhoA activity using GST-RBD, a substrate that binds to active RhoA, as seen by western blotting using phospho-specific antibodies. Similar results were obtained with GSK and DH. In summary, our study revealed that the interaction between FAK and cytoskeletal architecture plays a crucial role in regulating AQP2 recycling and its subsequent entry into the endocytic pathway. Thus, targeting FAK could be a potential therapeutic strategy for water balance disorders involving defective AQP2 reabsorption, such as nephrogenic diabetes insipidus.

This work was supported by NIDDK R01DK096015 (JHL) and DK096586 (DB).

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.
Targeting Cardiomyocytes with Adeno Associated Viruses to Protect Hearts from Trastuzumab-induced Cardiotoxicity
Authors: Reichelt Melissa , Ho Uda , Bunt Kelsey , Watson Sophie , Patel Kinjal , Bradford Julia , Thomas Walter G
Published: May 2024

Amplification of HER2 occurs in 20% of breast cancers. HER2 (known as ErbB2 in mouse) belongs to the Epidermal Growth Factor Receptor (EGFR) family that is responsible for cell growth and survival. While HER2 does not bind ligands, it forms heterodimers with HER1 (also known as EGFR) in the presence of its ligand EGF, and HER4 following stimulation with Neuregulin. In HER2-positive breast cancer where HER2 expression is high, HER2 homodimerizes leading to excessive activation of downstream signalling and cell proliferation. Current HER2-positive breast cancer treatment involves chemotherapy with drugs called anthracyclines, such as Doxorubicin, and an antibody targeting HER2 called Trastuzumab. This combination is effective in killing HER2-positive breast tumours, however, Trastuzumab alone or in combination with anthracyclines leads to severe cardiotoxicity and heart failure in 2.6-11% of cases, making it a dose-limiting side effect. We hypothesise that cardiac toxicity can be mitigated by targeting cardiomyocytes exclusively to express a mutated (but functional) version of HER2 that is not recognised by trastuzumab. We designed 3 HER2 variants wherein the trastuzumab binding domain was mutated to disrupt binding. These HER2 mutants were transfected into HEK293T cells, and we confirmed that all 3 successfully localised to the cell membrane, and did not bind trastuzumab. We have used bioluminescence resonance energy transfer to examine the capacity of all 3 mutants to activate recruitment of Grb2 to the HER2 as part of HER1/HER2 and HER4/HER2 heterodimers; Western blotting also confirming mutants were capable of stimulating ERK and Akt phosphorylation. Future studies will evaluate the effcacy of using AAVs to instruct cardiomyocytes to express these HER2 mutants in a murine model of breast cancer. We predict that this new therapy would not only mitigate cardiac toxicity, but would also permit higher doses of trastuzumab to be used to treat breast cancer.

This work is supported by Australia's National Health and Medical Research Council and the Australian Research Council.

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.
Exploring the Impact of Fibroblast Growth Factor 17 on Functional Recovery and Neuroinflammation in Spinal Cord Injury
Authors: Devine Caroline , Sunshine Michael , Alilain Warren
Published: May 2024

Spinal cord injury (SCI) affects more than 300,000 people in the United States, making it a significant and widespread problem. This includes injuries at the cervical level, which pose greater challenges due to respiratory in addition to mobility issues. Though there is a large societal impact there is still standard of care following spinal cord injury. While previous preclinical research has shown benefits from FGF1 and FGF2, there is weak data to suggest their clinical effcacy. A related compound, Fibroblast Growth Factor 17 (FGF17), has recently been described as a component within the CSF of young animals that when delivered to aged animals improved cognitive function. These improvements were associated with oligodendrogenesis. Spinal cord injury results in secondary demyelination, which may be mitigated by increasing oligodendrogenesis; this led us to examine how FGF17 may be used as a therapeutic agent following SCI. We used a rat C2 hemisection injury model to evaluate the effects of FGF17 at 4 hours, 2 and 6 weeks after injury. FGF17 was administered via intrathecal infusion at 25 μg/μl for 14 days at 0.5 μL/hour or a single application of 20 μL (4-hour timepoint). Following treatment, whole body plethysmography was performed weekly. Tissues were collected at endpoint to assess brainstem neuroinflammation via immunohistochemistry and molecular signaling pathways via western blotting. As anticipated, animals that were not treated with FGF17 had reduced tidal volume following spinal cord injury. Treatment with FGF17 partially preserved tidal volume as early as 3 days post injury. 6 weeks following spinal cord injury we observed a reduction in GFAP+ and IBA1+ staining in the brainstem near regions associated with respiratory control in animals treated with FGF17. Further, when we quantified the protein content in the spinal cord near the lesion epicenter we saw an increase in p-ERK 1/2 in all injured animals. However, in FGF17 treated animals we saw an increase in downstream transcription factors, STAT6 and Serum Response Factor. Serum Response Factor was implicated in oligodendrogenesis, ongoing studies will directly address this. These data suggest that FGF17 may be a viable alternative to the traditional fibroblast growth factor family members when treating spinal cord injury.

R21NS121966, R01NS116068.

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.
Inspiratory Muscle Strength Training to Improve Cardiometabolic Health in Patients with Type 2 Diabetes Mellitus
Authors: Reed Baylee L. , Gamez Gonzalez Esmeralda , Tavoian Dallin , Bailey E. Fiona , Funk Janet L. , Coletta Dawn K.
Published: May 2024

Type 2 diabetes mellitus (T2DM) is a complex, chronic metabolic disease that is associated with a high prevalence of comorbid conditions. Traditional lifestyle interventions (e.g., diet and exercise) can counter some adverse effects of T2DM; however, participation in these activities is low. High-resistance inspiratory muscle strength training (IMST) is a time-effcient and simple breathing exercise that significantly reduces blood pressure (BP) and improves vascular endothelial function in several nondiabetic populations. Herein, we performed a blinded, randomized, sham-controlled trial to investigate the effects of a 6-week IMST regimen (30 breaths/day, 6 days/week) on glycemic control and insulin sensitivity in adults with T2DM. Currently, we have eight participants (aged 35-71 years, 5 females and 3 males) who have completed either low-resistance sham training (15% maximal inspiratory mouth pressure, n=5) or high-resistance IMST (75% maximal inspiratory mouth pressure, n=3). Our data suggests that fasting plasma glucose and fasting serum insulin did not significantly change by IMST or sham training. Utilizing a homeostatic model assessment of insulin sensitivity to evaluate insulin action, our results indicate no change by either IMST or sham training. IMST revealed a trend towards a reduction in systolic BP (pre: 133.0 ± 4.8 vs. post: 128.8 ± 4.9) and diastolic BP (pre: 84.8 ± 2.7 vs. post: 81.7 ± 3.6). These findings align with prior research indicating improved resting BP, further corroborating previous studies. We performed an exploratory analysis to examine the potential impact of IMST on lipid levels. Interestingly, IMST resulted in a trend towards a reduction in cholesterol (pre: 259.3 ± 29.4 vs. post: 230.3 ± 3.7) and LDL (pre: 153.3 ± 19.7 vs. post: 127.7 ± 8.7). Analysis of the endothelial function data is forthcoming until we have enough individuals to complete those analyses. In conclusion, our results to date are preliminary; however, we expect to see continued improvements in resting BP and cholesterol/LDL with IMST. Moreover, with a higher number of individuals in the study (our goal is to have 12 in each group), we anticipate seeing changes in glycemia or insulin action. Lastly, IMST stands out as a distinctive and time-effective exercise method, addressing adherence challenges while demonstrating enhancements in cardiometabolic health. This could be particularly advantageous for T2DM patients with an increased cardiovascular disease risk.

University of Arizona College of Medicine SPARK Grant.

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.
Advanced Age Impairs the Neuromuscular Control of Peak Inspiratory Performance in Mice
Authors: Murphy Ben , Maxwell Michael , Marullo Anthony , O'Halloran Ken
Published: May 2024

Respiratory muscle wasting is known to occur in ageing adults resulting in a decreased capacity for force production and an associated reduction in high-threshold respiratory performance. Dysfunction of the respiratory musculature in this manner may contribute to an increased susceptibility to respiratory complications frequently observed in older populations. The objective of the current study was to characterise the respiratory phenotype during advanced age to assess the impact of sarcopenia on the neuromuscular control of respiratory performance. Male wild type (BL10) mice were studied at 6-months and 24-months, representing young and old age cohorts, respectively. In anaesthetised animals, inspiratory pressure and contemporaneous obligatory and accessory respiratory muscle electromyography (EMG) activities were measured during baseline and sustained tracheal occlusion (n = 9 young; n = 8 old). Diaphragm muscle contractile performance was assessed ex-vivo via tissue bath preparations (n = 8 young; n = 8 old). Furthermore, diaphragm and limb muscle tissues were harvested and snap frozen for subsequent structural and molecular analyses which will assess potential differences in cross-sectional area and relative fibre type composition. Peak inspiratory pressure was significantly reduced in 24-month-old compared to 6-month-old mice (P < 0.0001). Associated EMG activity was significantly lower (P < 0.05) in obligatory (external intercostal; parasternal) and accessory (cleidomastoid; scalene; trapezius; sternomastoid; sternohyoid) muscles of breathing in the old group compared to the young. Diaphragm EMG amplitude was not different between the groups. No differences were observed in the force-generating capacity of the diaphragm between young and old cohorts. Our preliminary results suggest an impairment in the neuromuscular control of the respiratory system during peak performance which apparently precedes the age-related decline in diaphragm muscle force generating capacity. Our further histological and molecular analyses will provide additional insight into the nature of this respiratory phenotype in advanced age.

This work was funded by the Department of Physiology, UCC. B.T. Murphy is funded by an Irish Research Council Doctoral 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.
Adaptations to maternal WSD-feeding and metformin use on fetal islets from non-human primate offspring
Authors: Thomas Carroll Darian , Fuhr Jennifer , Lindsley Rene , Kirigiti Melissa , Dean Tyler , McCurdy Carrie , Wesolowski Stephanie
Published: May 2024

Given the current increased prevalence of diabetes in pregnancy, the potential relative risks and benefits of oral glycemic agents on the developing offspring should be evaluated and considered. Metformin (Met) is a common oral glycemic agent prescribed in pregnancy that is not metabolized, but is renally excreted and actively transported across the placenta. Thus, the developing fetus is exposed to near equivalent maternal adult doses with subsequent risk of adverse consequences. Using a non-human primate model of maternal overnutrition, our group previously demonstrated that developmental exposure to a Western-style diet (WSD) results in an inappropriate increase in glucose-stimulated insulin secretion and changes in expression of several ion channels involved in insulin secretion in islets from juvenile offspring. Given that maternal overnutrition results in an excess energy supply to the developing fetus while Met inhibits mitochondrial respiration, we hypothesize that maternal WSD-feeding and Met will result in maladaptive beta-cell function in the fetus. Static insulin secretion assays on islets from chow (CD) and WSD +/- Met-exposed offspring show no differences in glucose-stimulated insulin secretion. Nevertheless, islets from a mWSD+Met-exposed fetus showed lower oxygen consumption and extracellular acidification rate relative to mWSD+placebo fetal islets, suggesting that maternal diet influences fetal programming and adaptation to Met in fetal islets. Therefore, we predict that the metabolic response to intrauterine Met exposure differs depending on the maternal diet. Elucidation of the mechanisms mediating adaptations to maternal diet and Met exposure during development may provide insight on interventions to avoid beta-cell failure in the offspring as they age.

All nonhuman primate studies were supported in part by the Oregon National Primate Research Center grant P51 OD011092 from the National Institutes of Health/Offce of the Director. D.T.C. was supported by the Vanderbilt University Training Program in Molecular Endocrinology (5T32 DK563-30) and a predoctoral fellowship from the NIH/NIDDK (1F31 DK135164).T.A.D., C.E.M., K.M.A., J.E.F., P.K., and M.G. were supported by NIH/NIDDK Grants R24 DK090964 and R01 DK128187.

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.