bluuebunny/crossref_metadata_2025_split huggingface dataset:
When undergraduate research becomes the curriculum
Authors: Dolan Erin 
Published: November 2023

National calls to improve undergraduate STEM education have emphasized the importance of undergraduate research experiences. Course‐based Undergraduate Research Experiences, or CUREs, involve groups of students in addressing research problems or questions in the context of a class, and have been proposed as scalable ways of involving undergraduates in research. This presentation will offer a definition of CUREs, describe what makes them distinctive from other learning experiences, and highlight results from the Freshman Research Initiative at the University of Texas Austin as a unique and highly impactful CURE model.Support or Funding InformationThis work was supported by a grant from the National Science Foundation (NSF DBI‐1061874) and two grants from the Howard Hughes Medical Institute (HHMI #52005907 and #52006958). The contents of the presentation are solely the responsibility of the author and do not necessarily represent the official views of the NSF or HHMI.
TREATMENT WITH PROLYL HYDROXYLASE INHIBITOR REVERSES PRE‐EXISTING DIASTOLIC DYSFUNCTION IN THE AGED SIRT3 KNOCKOUT MICE
Authors: He Xiaochen , Zeng Heng , Chen Jian‐xiong 
Published: November 2023

SIRT3 declines with aging and ablation of SIRT3 accelerates the development of cardiovascular diseases. Diastolic dysfunction is emerging as a leading cause of heart failure in aging population and diabetes. However, there is no effective treatment for diastolic dysfunction in the patients with heart failure. In the present study, we investigated the role of SIRT3 in the development of diastolic dysfunction and explored its potential mechanisms. We found that deletion of SIRT3 resulted in impairment of diastolic function, as evidenced by increased isovolumic relaxation time, myocardial performance index, and E/E′ ratio when compared to WT mice. We further investigated the molecular basis by which ablation of SIRT3 causes diastolic dysfunction in mice. Extracellular flux analysis indicated that SIRT3 deficient endothelial cells (ECs) exhibited higher mitochondrial oxygen consumption rate (OCR) than that of WT ECs. We also found that knockout of SIRT3 led to a significant increase in the expression of prolyl hydroxylase domain‐containing protein (PHD) 1 and 2, but a decrease in the expression of PHD3. We then investigated the involvement of PHD in the development of diastolic dysfunction by treatment of SIRT3 KO mice with PHD inhibitor, dimethyloxalylglycine (DMOG). Treatment with DMOG (25 mg/kg/day, i.p.) for 2 weeks increased the expression of hypoxia‐inducible factor (HIF)‐1α in the endothelium of coronary arteries. This was accompanied by a significant increase in coronary flow reserve, indicating improvement of coronary microvascular function. Intriguingly, treatment with DMOG reduced mitochondrial OCR in SIRT3 KO ECs and completely reversed the pre‐existing diastolic dysfunction in the SIRT3 KO mice. Our data demonstrates that disruption of the SIRT3/PHD/HIF signaling may contribute to the impairment of mitochondrial homeostasis and diastolic dysfunction in the SIRT3 KO mice. The present study provides a novel therapeutic approach for treatment of patients with diastolic dysfunction.Support or Funding InformationThis study was supported by National Institutes of Health RO1 HL102042 (Chen).
MitoQuinone Rescues Aortic Endothelial Function mediated through eNOS/NO pathway
Authors: Pung Yuh‐Fen , Kmetz John , Bratz Ian , Murphy Michael P , Smith Robin AJ , Chilian William M 
Published: November 2023

Although mitochondrial oxidative stress is known to occur in many models of cardiovascular disease, whether the mitochondrial stressor alone is sufficient to induce endothelial dysfunction, and the underlying mechanisms are unknown. Accordingly, Wistar Kyoto rats (WKY) were divided into 3 groups: Control; Rotenone (Rot): mitochondrial complex I inhibitor infused through Alzet pumps at 1.5 mg/kg, subcutaneously, to induce mitochondrial oxidative stress; MitoQ+Rot: mitochondrial targeted antioxidant, MitoQ, at 50 μM in drinking water to scavenge mitochondrial oxidative stress with Rot for 12 to 14 days. Aortae were collected from Control (n=7), Rot (n=6) and Rot+MitoQ (n=3) groups for functional and molecular analyses. Aortae from controls showed ~53.3% relaxation (isometric vascular ring preparation) in response to acetylcholine (ACh), Rot prevented ACh‐induced dilation suggesting endothelial dysfunction. MitoQ partially reversed the inhibitory effect of Rot (~35.8% vasodilation to ACh) suggesting that mitochondrial oxidative stress is central to this effect. Interestingly, relaxation to sodium nitroprusside (SNP) was greater in the Rot group (~55.1%), than in Control or MitoQ+Rot groups, suggesting that smooth muscle function is not compromised by mitochondrial oxidative stress. To delineate the underlying mechanism(s), enriched aortic ECs fractions were isolated from the groups. To our surprise, activation of eNOS (phosphorylation at s1177) was higher in ECs from Rot, than in Controls and Rot+MitoQ groups (ratio of p‐eNOS to total eNOS: 0.71±0.21 vs 0.44±0.08 and 0.45±0.17, respectively). Similarly, SOD‐2 expression (normalized to porin) was augmented in Rot group, suggesting a possible compensatory mechanism to scavenge excessive mitochondrial superoxide production (Rot: 4.25±0.78, Control: 2.98±0.62 and Rot+MitoQ: 1.38±0.03). Both functional and molecular data imply that mitochondrial oxidative stress uncouples eNOS (activation of eNOS with endothelial dysfunction) and scavenging mitochondrial oxidative stress rescues endothelial function. Collectively our study raises the possibility for mitochondrial therapies as a treatment for vascular disease.Support or Funding InformationThis work was supported by NIH Grants HL32788, R01 83366, RC1HL100828 (to WMC), American Heart Association Post‐doctoral Fellowship 09POST2290021 and Malaysia Ministry of Higher Education Grant FRGS/1/2015/SKK08/UNIM/03/2 (to YFP).
Gcn5l1 Promotes Enhanced Cardiac Fatty Acid Oxidation through Acetylation of Mitochondrial Proteins
Authors: Thapa Dharendra , Zhang Manling , Guimarães Danielle A , Stoner Michael W , O'Doherty Robert M , Shiva Sruti , Scott Iain 
Published: November 2023

Lysine acetylation is a reversible post‐translational modification, and is particularly important in the regulation of mitochondrial metabolic enzymes. Acetylation uses acetyl‐CoA derived from fuel substrate metabolism as a co‐factor, which links nutritional inputs to metabolic activity. The objective of this study was to investigate the role of mitochondrial acetylation in the heart. Specifically, we assessed how food intake controls cardiac mitochondrial acetylation and affects mitochondrial metabolism. Western blots, immunoprecipitations, qPCR and mitochondrial bioenergetic assessments were performed to achieve these objectives. We found that there was a significant increase in cardiac mitochondrial protein acetylation in mice fed with a long‐term high fat diet, and that this change correlated with an increase in the abundance of the mitochondrial acetyltransferase‐related protein Gcn5l1. Further, we show that the acetylation status of two mitochondrial fatty acid oxidation enzymes was significantly upregulated in high fat diet mice, and that this was linked to increase in their enzymatic activity. Finally, we demonstrate that the acetylation of mitochondrial fatty acid oxidation proteins is decreased following Gcn5l1 knockdown, and that reduced acetylation leads to diminished fatty acid oxidation in cultured H9C2 cells. Based on our findings, we conclude that lysine acetylation promotes fatty acid oxidation in the heart, and that this modification is regulated in part by the activity of Gcn5l1.Support or Funding InformationNHLBI K22HL116728
Myocardin regulates mitochondrial calcium homeostasis and prevents permeability transition in cardiac myocytes.
Authors: Gordon Joseph , Mughal Wajihah , Field Jared , Hai Yan , Chapman Donald , Keijzer Richard , Rattan Sunil , Dixon Ian , Huang Jianhe , Parmacek Michael 
Published: November 2023

Myocardin is a transcriptional co‐activator required for cardiovascular development and cardiomyocyte differentiation. Recent studies have shown that genetic inhibition of myocardin results in embryonic lethality with impaired cardiomyocyte proliferation and increased programmed cell death. Mitochondrial permeability transition, triggered by matrix calcium accumulation, has been implicated in regulated necrotic cell death, while permeability transition pore closure is involved with myocyte differentiation and mitochondrial maturation during development. We show that a genetic loss of myocardin function leads to endocardial necrosis, determined by HMGB1 staining, at embryonic day 9.5, concurrent with elevated expression of the death gene Nix. Mechanistically, we demonstrate that myocardin knockdown in primary ventricular myocytes reduces microRNA‐133a levels to allow Nix accumulation, leading to mitochondrial permeability transition, reduced mitochondrial respiration, and necrosis. Using organelle‐targeted calcium biosensors, we demonstrate that myocardin knockdown leads to sarcoplasmic reticulum (SR) calcium release and mitochondrial calcium accumulation, while mitochondrial permeability transition was prevented by pharmacological inhibition of the inositol triphosphate (IP3)‐activated calcium channel or the mitochondrial calcium uniporter. Gain of function studies confirm that myocardin can desensitize myocytes to permeability transition elicited by protein kinase‐A (PKA) activating agents by opposing SR calcium release. Furthermore, restoring microRNA‐133a function with mimicking oligonucleotides, or knockdown of Nix rescues mitochondrial calcium accumulation induced by myocardin knockdown. Molecular studies using Nix constructs targeted to the SR or mitochondria revealed that only SR‐targeted Nix leads to mitochondrial calcium accumulation, which could be attenuated by SR‐targeted Bcl‐2, but not mitochondrial‐targeted Bcl‐2. Finally, we observed reduced myocardin expression in vivo within the infarction border zone following coronary ligation in rodents, with corresponding reduced microRNA‐133a and elevated Nix expression. These findings identify a novel myocardin‐regulated genetic pathway that maintains cardiomyocyte calcium homeostasis and mitochondrial function during development, and is attenuated during ischemic heart disease.Support or Funding InformationSupported by NSERC Canada, the Thorlakson Foundation, Research Manitoba, and the Children's Hospital Foundation of Manitoba.
Elevated Pax3+ cell number potentially compensates for Pax7+ cell depletion in diaphragm muscle of running mice
Authors: Ghazala Lina S , Confides Amy L , Murach Kevin L , Ho Angel L , Jackson Janna L , McLoon Linda , Dupont‐Versteegden Esther E 
Published: November 2023

Satellite cell depletion in hind limb muscles has minimal effect on hypertrophy, sarcopenia, or the ability to adapt to aerobic exercise. However, whether the ability of the constantly active diaphragm muscle to adapt to a stressor such as exercise is decreased with a loss of satellite cells is unknown. We hypothesized that satellite cell depletion would negatively affect diaphragm muscle, particularly with running and in aged mice. We used the Pax7‐DTA mouse model to deplete over 90% of Pax7 positive cells in the diaphragm muscle upon treatment with tamoxifen which induces CreER‐mediated expression of DTA. Female mice were treated with vehicle or tamoxifen at 4 months of age and were either given running wheels at 6 (young) or 22 (aged) months of age or remained sedentary for 8 weeks after which they were euthanized. Satellite cell depletion was associated with 25–28% decreased running activity in young and aged mice. Satellite cell depletion had no effect on fiber type distribution or cross sectional area of fibers in both young and aged mice regardless of running activity. Also, minimal effect was observed on diaphragm function measured using ultrasound analysis. There was no significant difference in myonuclear abundance among treatment and activity groups suggesting that there may be another stem cell type present in diaphragm muscle of satellite cell depleted mice which could compensate for the loss of Pax7+ cells. We used fluorescent in situ hybridization to detect Pax3+ cells and found an increased abundance of these cells in young and aged diaphragm muscle in satellite depleted mice. Additionally, only very few Pitx2 positive cells were detected in young and aged diaphragm muscle and no difference was observed with satellite cell depletion. These results indicate that satellite cell depletion does not negatively affect diaphragm muscle in young and aged mice even under running conditions and we conclude that the increased presence of Pax3+ cells in satellite cell depleted diaphragm muscle potentially compensates for the loss of Pax7+ cells.Support or Funding InformationNIA AG043721 and APS Undergraduate Summer Research Fellowship.
Early Rehabilitation and Volumetric Muscle Loss Injury Adapts the Genetic Response of the Remaining Muscle Mass
Authors: Greising Sarah M , Corona Benjamin T , Warren Gordon L , Call Jarrod A 
Published: November 2023

Volumetric muscle loss (VML) injuries occur due to orthopaedic trauma or the surgical removal of skeletal muscle and result in debilitating long‐term functional deficits. Current treatment strategies do not promote significant restoration of function; it is possible that limitations to traditional rehabilitation may be related to the attenuated potential of the remaining muscle to adapt following injury. We examined early rehabilitation interventions involving range of motion, muscle stimulation, and pharmacologic targeting to augment mitochondrial capacity (via guanidionpropionic acid) in isolation or combination to understand the capability of the remaining muscle mass to adapt during the acute phase of healing after VML injury. Adult male mice underwent an ~20% multi‐muscle VML injury to the posterior compartment (gastrocnemius, soleus, and plantaris muscle) and were randomized to rehabilitation twice per week beginning 72 hours post‐injury or no treatment. During each 30 minute rehabilitation session, passive muscle torque, a measure of muscle stiffness, was recorded. At 3, 7, and 14 days post‐injury muscles from the injured and contralateral limb were harvested and used to quantify the fibrotic, myogenic, inflammatory, and mitochondrial gene expression. The response to VML injury and associated early rehabilitation appeared to be transient over days post‐injury. VML injury without rehabilitation was associated with a large initial increase in inflammatory gene expression at 3 days, which later decreased at 7 days and then increased again at 14 days post‐ injury. The myogenic gene response was initially increased at 3 days but then declined at both 7 and 14 days. Combined rehabilitation increased the acute myogenic response and suppressed the inflammatory response post‐injury. Under normal circumstances, mitochondrial biogenesis accompanies myogenic muscle recovery from injury and is likely to meet the energy demands of muscle repair. Mitochondrial genes were downregulated across all measured time points post‐ injury when left untreated; suggesting mitochondrial dysfunction following injury, with a combined rehabilitation approach this downregulation appears to be blunted. Collectively, early rehabilitation appears to mitigate the acute maladaptive response to VML injury. Additional work is needed to determine if long‐term functional gains can be accomplished by implementing early rehabilitation.Support or Funding InformationStudies funded by the Alliance for Regenerative Rehabilitation Research and Training Grant supported by the NICHD, NINDS, and NIBIB.
Exercise Mitigates Bone Loss in Type 2 Diabetes Mellitus Mice
Authors: Zhai Yuankun , Behera Jyotirmaya , Bala Jyoti , George Akash , Tyagi Suresh , Tyagi Neetu 
Published: November 2023

AIMThe aims of the present study were to investigate the effectiveness of exercise intervention on the bone loss in leptin receptor‐deficiency (db/db) type 2 diabetes mellitus mice, and examined the influence of homocysteine (Hcy) and hydrogen sulfide (H2S) level to clarify its molecular mechanisms.METHODSForty mice were used in our study, include twenty db/db control mice and twenty db/db mice. All these mice were divided into four groups, db/db control (CT), db/db control plus exercise (CT+EX), db/db mice (DB), db/db plus exercise (DB+EX), every group have 10 mice. CT+EX and DB+EX were present in the treadmill training for 8 weeks (7 m/min the first week, 10 m/min the second week, and 11 m/min third week until the end. Run for 330 m total with a 5 minute break every 110 m, 6 times/week). After sacrificed, alkaline phosphatase (ALP), tartrate‐resistant acid phosphatase 5b (TRACP‐5b), and gasotransmitter [hydrogen sulfide (H2S) and nitric oxide (NO)] in serum were assayed, bone quality, including bone mineral density (BMD), micro structure, biomechanical parameters were measured by DXA, micro CT and three bending test separately. Total mRNA and protein were isolated, and factors in Hcy/H2S cycle were detected by western‐blot and RT‐PCR.RESULTSPhysical exercise induced lose bodyweight, especial in DB+EX (P < 0.05), also decreased the blood glucose (P < 0.01), but showed no effects on db/db control mice. Exercise increases the bone quality index (BMD, trabecular microstructure, break force) both in db/db control mice and db/db mice, but there also shown a more obvious difference in db/db mice than db/db control mice. We also found exercise decrease the Hcy level, but increase H2S level in serum in db/db mice. Exercise regulate the factors involved in homocysteine metabolism to balance the level of Hcy and H2S, such increased MTHFR and CBS, but decreased SAHH.CONCLUSIONThe exercise intervention could decrease bodyweight and blood glucose in db/db mice, proved moderate exercise is helpful for diabetes treatment. Meanwhile, exercise also rebalance the Hcy and H2S level in db/db mice, and then prohibit bone loss. All these results represents that moderate exercise improve bone quality in type 2 diabetes patients who also with secondary osteoporosis.Support or Funding InformationFinancial support from National Institute of health grant AR‐067667 and HL‐107640 are greatly acknowledged.
Transcriptional regulator PGC1α regulates amino acid metabolism activated by exercise in skeletal muscles
Authors: Hatazawa Yukino , Miura Shinji , Kamei Yasutomi 
Published: November 2023

Skeletal muscles play important roles not only in exercise and nutrition metabolism, but also in human health. Peroxisome proliferator‐activated receptor (PPAR) γ coactivator 1α (PGC1α) is a coactivator of various nuclear receptors and other transcription factors, whose expression increases in the skeletal muscles during exercise. We have previously made transgenic mice overexpressing PGC1α in skeletal muscles (PGC1α‐Tg mice). PGC1α Tg mice showed increased red fiber and capacity for longer treadmill running. In this study, we analyzed metabolic changes of skeletal muscles in PGC1α‐Tg mice by global gene expression (microarray) and metabolomic analyses.Microarray data indicated that branched chain amino acid (BCAA) metabolism was activated in skeletal muscles of PGC1α‐Tg mice. Moreover, we observed that gene and protein expression of BCAA metabolism‐related enzymes were increased in PGC1α‐Tg mice (Hatazawa et al. PLOS ONE. 2014). Then, we examined low molecular weight compounds, especially water‐soluble metabolites, in skeletal muscles of PGC1α‐Tg mice by metabolomic analyses. Metabolic products of the TCA cycle increased in PGC1α‐Tg mice. Levels of β‐alanine and related metabolites, which may serve as a substrate for the TCA cycle, were markedly decreased in PGC1α‐Tg mice. Moreover, our metabolomics data showed the activation of the purine nucleotide pathway, malate–aspartate shuttle, and creatine metabolism, which are known to be active during exercise. Expression of these genes related with these pathways was increased in PGC1α‐Tg mice. Thus, the data suggests that PGC1α provide an energy source during exercise by using amino acids, including BCAA, as a substrate for the TCA cycle and activating the cycle. Meanwhile, PGC1α overexpression in skeletal muscles increased the muscle content of gamma‐aminobutyric acid (GABA), gamma‐aminoisobutyric acid (BAIBA) and serotonin, suggesting that these amino acid‐related molecules might act as secretory bioactive molecules (myokines) that have effects on other organs. Namely, this may be a new mechanism that explains the interaction of multiple organ networks in lifestyle diseases affected by exercise (Hatazawa et al. PLOS ONE. 2015).
Pyruvate Dehydrogenase Activity in Red and Superficial White Gastrocnemius Muscles of the Rat during Contraction
Authors: Kasper Jonathan D , Lewis Matthew T , Gudziak Gregory L , Meyer Ronald A , Wiseman Robert W 
Published: November 2023

The increase in glucose oxidation during exercise is dependent upon the mitochondrial enzyme pyruvate dehydrogenase (PDH) which is allosterically regulated by reversible phosphorylation through a family of PDH kinases and phosphatases. However, the relationship between PDH activation and muscle fiber type during exercise has not been well described because fiber specific muscles have not been reported, and, because voluntary exercise involves motor unit recruitment which further complicates interpretation. To determine whether PDH activation differs in red versus superficial white muscle in vivo, gastrocnemius muscle contractile activity was controlled by electrical pacing via surgically implanted electrodes on the sciatic nerve of anesthetized male Wistar rats. Muscle force production of the triceps surae muscle group was recorded from the Achilles tendon and the knee pinned in place with a tungsten rod through the head of the femur. Gastrocnemius muscle samples were collected from the superficial white (predominantly Type IIb fibers) and deep red (predominantly Type IIb fibers) portions and freeze clamped at rest and during 5 min of twitch stimulation at 0.5Hz and 1.0Hz intensities. PDH activity was assayed in vitro using a radioisotopic tracer assay with [2‐14C]‐pyruvate as the substrate. Total PDH activity in the deep red gastrocnemius was almost two‐fold greater than that of the superficial white (1.9±0.1 vs 1.1±0.1 U/gWW, n=15). Fractional PDH activity (% total activity) was significantly increased in muscle samples collected from superficial white relative to deep red gastrocnemius at rest (15.0±2.0 vs 9.5±0.7%), and during 0.5Hz (60.9±8.1 vs 37.4±3.9%), and 1.0Hz stimulation frequencies (68.3±2.8 vs 40.5±2.8%) (n=4–5 for all groups). However, the active fraction of PDH activity was not different when comparing superficial white to deep red gastrocnemius at rest (0.12±0.02 vs 0.15±0.02 U/gWW) or during stimulation at 0.5Hz (0.67±0.08 vs 0.71±0.04 U/gWW), or 1.0Hz intensities (3±0.08 vs 0.82±0.02 U/gWW). These data suggest that the active fraction of PDH is dependent on the contraction intensity and therefore muscle fiber type differences do not appear to play a role in the number of PDH active sites during contractile activity. Therefore future designs of therapeutic exercise to optimize glucose disposal should be chosen based on the maximal intensity that can be maintained without fatigue to maximize the working muscle mass and PDH activity.Support or Funding InformationSupported by NIH DK095210