bluuebunny/crossref_metadata_2025_split huggingface dataset:
Muscle atrophy is coupled with ferroptosis in the skeletal muscle of Friedreich’s ataxia
Authors: Jee Eunbin , Medha Maisha , Kim Yuho , Kim Jonghan 
Published: May 2024

Friedreich’s ataxia (FRDA) is a rare genetic disorder caused by an expansion of GAA repeats in the frataxin gene (FXN), resulting in frataxin deficiency. As frataxin is crucial for mitochondrial function by recruiting key iron components such as iron-sulfur clusters and hemes, FRDA is characterized by mitochondrial dysfunction along with abnormal iron metabolism. Recently, ferroptosis, an iron-dependent cell death, has been suggested to play an important role in the development of FRDA, yet if and how ferroptosis impacts FRDA-related muscle weakness has not been studied. Therefore, the objective of this study was to identify the role of ferroptosis in the skeletal muscle of FRDA using whole-body frataxin deficient mice (Fxnnull::YG8s(GAA)>800, #030395, The Jackson Laboratory). FRDA mice (male, 3-months old) had a significantly smaller ratio of muscle mass to body mass, compared to strain-, age-, and sex-matched C57BL/6J control mice, suggesting that this animal model develops muscle atrophy as early as 3 months old upon frataxin deficiency. Furthermore, the FRDA muscles showed elevated non-heme iron levels, which were accompanied by altered iron regulatory protein expressions, including ferritin and ferroportin. In addition, mitochondrial function was decreased in the skeletal muscles of FRDA mice, as evidenced by significantly decreased protein levels of oxidative phosphorylation complexes (OXPHOS I, II, and III; decrease by 31%, 26%, and 15% compared to control, respectively), as well as other mitochondrial capacity markers such as nuclear factor erythroid 2-related factor 1 (Nrf1) and heme oxygenase-1 ( p=0.06). Notably, ferroptosis markers such as Nrf2 and glutathione peroxidase 4 were significantly downregulated in the skeletal muscles of FRDA mice, while apoptotic markers (p53 and caspase 3) were not altered. Collectively, ferroptosis could promote FRDA-related muscle atrophy, which is associated with abnormal mitochondrial iron status and function. Our results also suggest that ferroptosis may represent a novel target for correcting or ameliorating the development and progression of muscle atrophy in FRDA patients. Future studies are warranted to determine the molecular mechanism of ferroptosis in FRDA-related mitochondrial dysfunction and to develop therapeutic strategies for muscle weakness in FRDA or other types of ataxias. This study was supported in part by the NIH NS121394 and UMass Lowell Internal Seed 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.
Liraglutide protects against microvascular dysfunction and sepsis-mediated inflammation and organ injury
Authors: Aslaner David , Baer Brandon , Meegan Jamie , Bastarache Julie , Ware Lorraine 
Published: May 2024

Introduction: Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection characterized by increased systemic inflammation and microvascular injury. Recently, commonly used diabetes and obesity medications, glucagon-like peptide-1 (GLP-1) receptor agonists, have demonstrated unexpected anti-inflammatory effects. We tested GLP-1 receptor agonist liraglutide in a clinically relevant two-hit murine model of polymicrobial abdominal sepsis and hyperoxia and microvascular endothelial injury in vitro, hypothesizing that GLP-1 receptor agonists exert protective effects during sepsis, limiting microvascular permeability, inflammation, organ injury and death. Methods: Sepsis was induced in male and female mice by intraperitoneal (IP) injection of cecal contents (CS;1.8 mg/g body weight) collected from euthanized donor mice. Mice were also exposed to hyperoxia (FiO2 90-96%) for 24 hours. Six and 18 hours after CS injection, mice were administered saline or liraglutide (0.1 mg/kg). At 12 hours, mice were given fluids and antibiotics. At 24 hours, mice were euthanized for plasma and bronchoalveolar lavage (BAL; right lung) collection. Plasma cytokines, organ injury markers, and BAL immune cells and protein were measured. The left lung was tied off and excised to measure wet-to-dry lung weight ratios. Additionally, for in vitro studies, primary human lung microvascular endothelial cells (HLMVECs) were treated with saline or liraglutide for 24 hours prior to saline (control) or LPS (100 ng/mL). HLMVEC barrier dysfunction was quantified using express permeability testing (XPerT) assay or Electric Cell-Substrate Impedance Sensing (ECIS) to measure transendothelial electrical resistance (TER). Results: In murine sepsis, illness severity scores and lung injury were improved in mice pretreated with liraglutide (N=12). Plasma blood urea nitrogen (BUN; P=0.0581), alanine transaminase (ALT; P=0.0311) and aspartate aminotransferase (AST; P=0.0263), and cytokines IL-1β (P=0.0078), IL-6 (P=0.0038), and TNF-α (P=0.0183) in plasma were reduced in mice treated with liraglutide. In HLMVECs, liraglutide (1.5 nM) significantly reduced LPS-induced barrier dysfunction measured by XPerT assay (P=0.0030) and ECIS (P=0.0075). Conclusion: Liraglutide reduces illness severity, inflammation, and organ injury in a two-hit model of sepsis-induced ALI. Liraglutide has direct effects in the microvascular endothelium, limiting LPS-mediated barrier dysfunction. These findings support a protective role for GLP-1 receptor agonism in sepsis, mediated through the microvasculature. HL150783, AG075341, HL158906. 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 impact of repeat opioid use (ROU) on fentanyl-induced respiratory depression
Authors: Rai Karan G. , Nwakudu Chinwendu U. , Szujewski Caroline C. , Tryba Andrew K. , Garcia Alfredo J. 
Published: May 2024

Objective: Repeat opioid use (ROU) is a primary driver for the ongoing opioid epidemic, and while a substantial understanding exists for the impact of ROU on behavioral neurophysiology, the consequences of ROU on respiratory-related physiology including opioid-induced respiratory depression (OIRD) remain poorly understood. Hypothesis: ROU leads to respiratory tolerance to fentanyl that is characterized by the blunting of respiratory depression and improvement of O2 consumption (VO2). Methods: We utilized a pre-clinical rodent model. Breathing was measured via whole body-plethysmography in freely behaving adult mice (P>90) prior to and immediately following fentanyl administration. A single dose of fentanyl (0.7 mg/kg, i.p.) was given for up to 6 consecutive days. In a subset of experiments, O2 consumption was measured simultaneously using whole-body plethysmography. Results: We identified two distinct respiratory phenotypes in response to OIRD following ROU. Type 1 phenotype (n=18) adapted over time where breathing during OIRD is greater on day 5 versus day 1. In contrast, the Type 2 phenotype (n=5) showed no such adaptation, with unchanged or worsened breathing by day 5. In a subset of animals (n=12) the relationship between breathing (i.e. minute ventilation (Ve)) and oxygen consumption (VO2) was examined before and following ROU. Under baseline conditions the Ve to VO2 relationship positively correlated on day 1 and 5. During OIRD on day 1 this correlation became negative, but began to normalize by day 5, resembling the baseline relationship. These phenomena also coincided with an increase in the ventilatory drive observed at the whole-animal level and in the isolated preBötzinger complex following ROU. Conclusions: ROU leads to two distinct respiratory phenotypes in response to OIRD, where the majority of subjects show a blunted respiratory depression. Additionally, ROU improves the relationship between breathing and oxygen consumption and enhances inspiratory drive in the presence of fentanyl. These findings suggest that fentanyl-induced hypoxia experienced by repeat opioid users vastly differ from naïve users. Such differences may contribute to the unpredictable occurrence of overdose amongst repeat users. This work was supported by NIH: R01 HL163965 and DA057767. 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 and tissue-specific downregulation of miR410-3p in a mouse model of cardiometabolic diseases
Authors: Alnoud Mohammed , Elgazzaz Mona , Martinez Alexa , Miao Kevin , lazartigues Eric 
Published: May 2024

The brain Renin-Angiotensin System (RAS) plays a pivotal role in controlling cardiometabolic homeostasis, fluid balance, and other functions including inflammation. Previous studies have shown that more than a thousand microRNA (miRNA) families regulate RAS genes expression, and their dysregulation has been associated with HTN, cardiac ischemia, and aging. Recently, we observed that hypercaloric diet (HCD) programming resulted in differentially expressed miRNA in the hypothalamus of only the male progeny, including miR-410-3p which is thought to target angiotensin-II type 1 receptors (AT1R). Here, we aimed to investigate whether miR-410-3p regulate AT1R expression in a mouse model of cardiometabolic disease (CMD) exhibiting hypertension, diabetes and obesity. C57BI/6J mice (3-week-old, both sexes, n=10) were fed a HCD (D12492. 60 kcal% Fat, Research Diets, USA) while weight and fasting blood glucose levels were measured weekly to ensure the acquisition of metabolic syndrome. At 12 weeks of age, the mice were infused subcutaneously (osmotic pump model 1004, Alzet) with Ang-II (600 ng/kg/min/4 weeks). Gene expression of miR-410-3p (QRT-PCR) was reduced in the hypothalamus of CMD male mice (0.5 ±0.1 vs.1.0 ±0.1, p<0.05) but increased in females (1.6 ±0.4 vs.0.7 ±0.2, p<0.001), while both sexes showed a reduction in the heart (Males: 0.2 ±0.0 vs.1.7 ±0.3; Females: 0.23 ±0.0 vs. 3.2 ±0.3, p<0.01). AT1R protein expression (Capillary Western) was increased in the hypothalamus of CMD male (1.5 ±0.1 vs.1.0 ±0.2, p<0.05) mice but not in females (1.0 ±0.1 vs.1.2 ±0.1, P>0.05) while both sexes exhibited elevated levels in the heart (Males: 2.0 ±0.1 vs. 1.0 ±0.1; Females: 2.3 ±0.1 vs. 1.3 ±0.2, p<0.05). Binding specificity (luciferase assay) was further assessed between miR-410-3p and the 3’UTR of AT1R. Binding was decreased in presence of miR410-3p mimic (0.9 ±0.0 vs. 2.1 ±0.0; p<0.001) and enhanced by a miR410-3p inhibitor (2.5 ±0.1 vs. 2.1 ±0.0; p<0.01), confirming that AT1R is a direct target of miR410-3p. Together, our data suggest that in CMD downregulation of miR410-3p is associated with the upregulation of AT1R both in the hypothalamus and heart, notably in males. This positions miR410-3p as a possible new therapeutic strategy to control RAS overactivity in CMD. This work was supported in part by a research grant from the National Institutes of Health (HL163588). 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.
APOE Genotype Differentially Regulates Respiratory Motor Plasticity in the Active vs Rest phase
Authors: Marciante Alexandria , Mitchell Gordon 
Published: May 2024

Acute intermittent hypoxia (AIH) elicits respiratory motor plasticity and is emerging as a promising strategy to improve breathing and other (non-respiratory) movements in clinical disorders that end life due to respiratory insuffciency ( e.g., spinal cord injury & ALS). AIH-induced phrenic long-term facilitation (pLTF) is the most commonly studied form of respiratory motor plasticity and presents as a persistent increase in phrenic nerve activity after AIH. Specific factors ( e.g. aging, inflammation, time of day) undermine AIH-induced pLTF. However, little information is available concerning the role of specific genes that regulate AIH-induced phrenic motor plasticity. Apolipoproteins (ApoE) are highly expressed in the central nervous system and function as lipid carriers. The APOE gene is tri-allelic ( E2, E3 and E4); ApoE2 and E3 proteins are associated with neuroprotective and neuro-neutral phenotypes, respectively. ApoE4 impairs synaptic plasticity and is implicated in neurodegeneration, particularly Alzheimer’s Disease. Indeed, we recently discovered that specific APOE alleles predict human expression of mAIH-induced plasticity in cortico-spinal pathways to the phrenic/diaphragm motor system. Initial experiments using human APOE4 knock-in rats demonstrate a causal effect in limiting phrenic motor plasticity (vs APOE3) during the active phase. However, the impact of APOE genotype on respiratory plasticity across the daily rest/active cycle is unknown. We tested the hypothesis that APOE4 undermines AIH-induced pLTF vsAPOE3 in a time-of-day-dependent manner. Anesthetized, vagotomized, paralyzed and ventilated adult (3-4 months) male Sprague-Dawley rats with knock-in humanized (h) APOE3 and h APOE4 were presented with AIH (15,1 min hypoxic episodes; arterial PO2 = 40-50mmHg). During the active phase, AIH-induced pLTF was significantly greater in h APOE3 (33±11%) vs h APOE4 rats (-26±7%; p<0.001; both n=6). In contrast, rest phase AIH-induced pLTF was similar in both h APOE3 and h APOE4 rats (121±12% and 122±5%, respectively; both n=7). These experiments demonstrate a causal relationship whereby APOE genotype and time-of-day interact to undermine AIH-induced pLTF in a manner that is unique to the active phase in rats. Since AIH has emerged as a promising neurotherapeutic to preserve/restore breathing in clinical disorders such as spinal cord injury and neuromuscular disease, understanding how genetic factors and time-of-day of AIH delivery impact phrenic motor plasticity will help identify individuals most/least likely to respond to treatment and reveal new targets for precision interventions of AIH. NIH R01HL148030 (GSM), NIH R01HL149800 (GSM), NIH T32HL134621-5 (ABM). 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.
Does actin polymerization contribute to closure of the avian ductus arteriosus (Gallus gallus)?
Authors: Rippamonti Jessica , Dzialowski Edward 
Published: May 2024

The ductus arteriosus (DA) is a cardiovascular embryonic shunt present in all developing land vertebrates. This oxygen-sensitive blood vessel plays the important role of connecting the pulmonary artery to the aorta during development and directs blood flow toward the fetal respiratory organ (placenta in mammals or chorioallantois in birds and reptiles). Permanent vessel closure upon birth or hatch is necessary to establish proper circulation in the neonate. Increased arterial PO2 at birth or hatch stimulates DA closure via smooth muscle contraction. Smooth muscle contraction, such as in the DA, is governed by myosin light chain kinase (MLCK) stimulating increased cross-bridge cycling, and through increases in actin polymerization. The Ras homologous protein family (Rho) of GTPases are involved in calcium sensitization and contraction of vascular smooth muscle but have mostly been studied for their role in cell migration and signaling. Rho GTPases activate the Rho activated kinase (ROCK) pathway, which works in conjunction with MLCK to generate smooth muscle contraction as well as activating LIM kinase which inhibits the actin depolymerizer cofilin. Rac and Cdc42 GTPase pathways increase contractile strength in smooth muscle cells by activating the nucleator Arp2/3, leading to increased actin polymerization. The role of these GTPase pathways during closure of the DA is unknown. We examined the role of the Rho, Rac, and Cdc42 GTPase pathways leading to actin polymerization for their role in the closure of the avian DA in late-term chicken ( Gallus gallus) embryos. We hypothesized that inhibiting the pathways that lead to actin polymerization will inhibit tension development in the DA. Using a Danish Myo Technology wire myograph, DA physiology was examined when exposed to 25% oxygen followed by activators and inhibitors of the Rho, Rac, and Cdc42 GTPase pathways. Activation of Rho A pathways with CN01 (0.2 units/ml) produced contraction of the DA. Blocking ROCK pathways with Y-27632 (10 mM) removed the O2-sensitivity of the vessel, while the vessel was still able to respond to phenylephrine (100 mM). This suggests the Rho pathway is involved in maintaining baseline tension and contractile response to O2. Exposure to inhibitors of Rac (10 uM EHT 1864) and Cdc42 (via ML141) GTPases blocked the ability of vessels to contract in response to 25% oxygen, even after 3 hours of constant O2. Similarly, inhibition of the Arp2/3 complex (100 uM CK666) reduced the ability of the vessel to respond to oxygen. These findings suggest that Rho A, Rac, and Cdc42 pathways play a role in active tension of the chicken DA during development by potentially increasing actin polymerization. This research was funded by Grant R15HL14887 from NIH-NHLBI. 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.
Signaling of GPR17 in Hepatic and Renal Tissues
Authors: Spellman Michael , Samimi Safa , Kurtz Ryan , Shepard Blythe 
Published: May 2024

G protein-coupled receptors (GPCRs) are the largest class of proteins in the human body and are considered to be excellent targets for drug discovery. However, the vast majority of GPCRs are understudied. Using a large-scale TaqMan array screen on both male and female C57BL6 murine livers, we identified GPR17 as one of the most highly expressed orphan receptors within the liver (ΔCt = 19.9, normalized to GAPDH). GPR17 expression in the liver was confirmed using reverse transcriptase polymerase chain reaction (RT-PCR) and was also identified in murine whole kidney from both males and females indicating that GPR17 RNA expression is not sex-dependent. While GPR17 has known roles in oligodendrocyte maturation and myelination in the central nervous system, its functions within the liver and kidney are undetermined. To investigate its physiological functions, we started by uncovering its localization within the liver and kidney and identifying its ligand profile. A series of RNAScope in-situ hybridization assays were performed to localize GPR17 within hepatic tissue. Gpr17 mRNA was found within hepatocytes indicating that its highest expression is in the parenchymal cells of the liver. To identify possible activators for GPR17, we cloned the coding region into both flag-tagged PME18s and the Presto-Tango vectors. Live-cell surface labeling of HEK293T expressing the GPR17 constructs confirmed robust surface expression on the plasma membrane facilitating ligand screening. GPR17 downstream signaling has yet to be studied. Thus, we used the PRESTO-TANGO assay, an exogenous chemical ligand screening assay that relies on a luminescence readout to indicate -arrestin recruitment and receptor activation. A large, non-biased chemical screen of over 500 physiological compounds was tested for activation of GPR17. To date, we identified seven exogenous activators of GPR17: 3-[methyl(1,2,3,4- tetrahydronaphthalen-2-yl)amino]pyrazine-2-carbonitrile, 4-(4-fluorophenyl)-5-methyl-N-(2-methyl-1-oxo-1,2,3,4-tetrahydroisoquinolin-7-yl)thiophene-2-carboxamide,({1-[(2-chlorophenyl)methyl]-3,5-dimethyl-1H-pyrazol-4-yl}methyl)(methyl)[(1-methyl-1H-imidazol-2-yl)methyl]amine,N,N-dimethyl-6-[(5-phenyl-1,3-oxazol-2-yl)methyl]-5H,6H,7H,8H-pyrido[4,3-d]pyrimidin-4-amine,4-phenyl-1-[6-(pyrrolidin-1-yl)-9H-purin-9-yl]butan-2-ol, 2-(3-fluorophenyl)-3-methyl-1-{[1,2,4]triazolo[4,3-a]pyridine-6-carbonyl}pyrrolidine, and 2,6,6-trimethyl-N-({2-methyl-4H,5H,6H,7H-pyrazolo[1,5-a]pyrimidin-6-yl}methyl)-4,5,6,7-tetrahydro-1-benzofuran-4-amine. Ongoing studies are aimed at narrowing down the in vivo activators of GPR17 to ultimately shed light on the physiological functions that this receptor plays in the kidney and liver. NIH/NCATS. 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.
Proteomic and Transcriptomic Analysis of Human Colonoids Exposed to Bacterial Serine Protease, EspP
Authors: Thompson Myranda , Appell Lidia , Atanga Roger , In Julie 
Published: May 2024

Gut regeneration mechanisms remain an important, yet elusive, facet of intestinal injury research. The intestinal epithelium must be intact for critical gut functions to remain in place, yet injury via microbe interactions or environmental toxicants is common. EspP is a potent serine protease that functions as a cytotoxin and is secreted by enterohemorrhagic Escherichia coli. This bacterial toxin has been recently shown to cause significant colonic epithelial damage in human colonoids. Previous proteomics and single cell RNA-seq analysis of human colonoids exposed to EspP found that there is a marked expansion of enteroendocrine cells (EECs) at acute exposures. There is also an increase in vascular endothelial growth factor (VEGF)A and B, but the reasons for this remains unknown. Therefore, our goals are to understand the effects of altered secretory lineage differentiation upon EspP exposure during EHEC infection and characterize angiogenesis as a key factor in disease progression. We hypothesize that EspP induced EEC differentiation leads to increased enterohormone section, such as 5-HT, which ultimately influences the mucosal immune response and indirectly leads to increased VEGFA and VEGFB expression. Together, these factors promote systemic disease progression through epithelial-endothelial interactions. Human colonoids derived from healthy adult colonic biopsies (UNM IRB approved study 18-626 and 18-171) were established and shown to physiologically model the colonic epithelia. Colonoids were acutely exposed to EspP. Control and EspP-exposed colonoids (n=3 unique donors) were dissociated into single cells and processed for droplet-based single cell sequencing (scRNA-seq) or tandem mass spectrometry. The scRNA-seq data was analyzed using the Seurat pipeline and integrated with the proteomics dataset. scRNA-seq results identified a 4-fold expansion of EECs, with increases in EEC hormones 5-HT and PYY as well as a 2-fold expansion of VEGF expression. These transcriptomic changes seen were validated in colonoids (>5 biologically unique human donors) via RNA FISH and immunofluorescence. Our results demonstrate that acute EspP exposure directly induces transcriptomic and cellular changes in intestinal epithelia independent of microbiota, stroma, and immune cells. As EEC expansion is seen broadly in disease states from colorectal cancer to celiac disease, determining the role of enterohormones upon these changes, as well as the function of EECs during acute injury, will fill a gap in knowledge relevant to a wider problem of intestinal dysfunction. This work was supported by grants from the National Institutes of Health: K01DK106323, R56ES034400, P42ES025589; and AGA SURF. 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.