bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lack of Sestrins Is Associated with Increased Glycolytic Flux
Authors: Roberson Paul , Johnson Ginger , Jackman Matthew , Libby Andrew , Solt Claudia , Reisz Julie , D' Alessandro Angelo 
Published: May 2024

Introduction: Sestrin1, 2, and 3 are a family of stress-response proteins implicated in many diseases. How Sestrins affect cell survival through AMP-activated kinase (AMPK) and protein synthesis through mechanistic target of rapamycin in complex 1 (mTORC1) is most studied; however, how Sestrins affect metabolism is poorly understood. Hypothesis: Independent of AMPK/mTORC1 activation, Sestrins negatively regulate glycolytic flux by inhibiting glycolytic enzyme activity through binding inhibition. Results: Wildtype (WT) HEK293T cells were transfected with plasmids expressing individual FLAG-tagged Sestrins and then deprived of glucose for 180 min or deprived of glucose for 150 min followed by glucose addback for 30 min. FLAG-tagged Sestrins were immunoprecipitated and found to directly interact with Hexokinase2 and Phosphofructokinase such that binding inversely correlates with glucose concentration. Additionally, WT and Sestrin-knockout (TKO) HEK293T cells were subjected to the glycolytic and mitochondrial stress tests and analyzed for metabolic flux via Seahorse analysis. TKO cells demonstrated higher glycolytic flux, but lower mitochondrial flux, compared to WT cells. Cells were then treated with inhibitors against AMPK and mTORC1 and subjected to the glycolytic stress test. Surprisingly, glycolytic flux in TKO cells was unaffected by the inhibitors while WT cells reduced glycolytic flux suggesting Sestrins can regulate glycolytic flux independent of AMPK/mTORC1 activation. Thereafter, WT and TKO cells were glucose-deprived for 120 min or glucose-deprived for 110 min followed by glucose addback for 10 min and then characterized by steady-state metabolomics. As expected, TKO cells possessed elevations in glycolytic metabolites with glucose addback compared to WT cells. Similarly, WT and TKO cells were deprived of glucose for 110 min followed by stable isotope tracing with [13C6]glucose for 10- and 30-minutes and metabolites were profiled by mass spectrometry. TKO cells possessed higher abundances of glycolytic metabolites as well as elevated labeled extracellular lactate. Conclusions: These data support a model wherein Sestrins directly act as negative regulators for glycolytic enzyme activity, thus regulating glycolytic flux. This work is funded by F32DK126312 (P.A.R.), P30DK048520 Pilot and Feasibility Award (P.A.R.), T32DK120521 (A.E.L.), P30CA046934 Cancer Center Support Grant, R01AR080051 (A.B.), R01DK015658 (S.R.K.), P30DK048520 (P.S.M.). 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 Sex on the β-Adrenergic Receptor Contribution to Hypoxic Vasodilation
Authors: Bond Braden , Jacob Dain , Shariff Brian , Boyes Natasha , Harper Jennifer , Bostick Brian , Limberg Jacqueline 
Published: May 2024

Introduction: Hypoxia elicits peripheral vasodilation to preserve oxygen delivery to tissues. Approximately 10% of hypoxic vasodilation has been attributed to β-adrenergic receptors on the vascular endothelium and smooth muscle. Based on data supporting greater vascular β-adrenergic receptor responsiveness in females compared to males, we examined the effect of sex on the relative contribution of the β-adrenergic receptors to hypoxic vasodilation. We hypothesized β-adrenergic receptor blockade (oral propranolol, 1 mg/kg) would attenuate hypoxic vasodilation and the effect would be greater in females compared to males. Methods: Five female (26±8 yrs, 22±2 kg/m2) and eight male (27±7 yrs, 26±2 kg/m2) participants completed two randomized, single-blinded, and placebo-controlled visits (NCT05256069). On each visit (placebo, propranolol), forearm blood flow (venous occlusion plethysmography) and blood pressure (BP, finger photoplethysmography) were measured during normoxia (SpO2 ~98%) and hypoxia (SpO2 ~80%). Blood flow was normalized for mean BP and expressed as forearm vascular conductance (FVC). The relative change in FVC with hypoxia (%FVC = Hypoxia − Normoxia / Normoxia x 100) was assessed as an index of hypoxic vasodilation. Differences in %FVC between study visits (propranolol − placebo) are reported. Results: %FVC was unaffected by β-adrenergic blockade in female (placebo 15±14%, propranolol -1±15%, p=0.066) and male (placebo 19±25%, propranolol 16±15%, p=0.755) participants. Any effect of β-adrenergic receptor blockade on hypoxic vasodilation did not differ by sex (females: -16±14%, males -3±29%; p=0.383). Conclusion: These preliminary data suggest any effect of β-adrenergic receptor blockade on hypoxic vasodilation does not differ between young healthy female and male participants, although studies are ongoing. Our results further understanding of the effect of sex on vascular control mechanisms during hypoxia. Funding: AHA 909014 (DWJ), APS-SURF (BJB), HL153523 (JKL). 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.
Effects of Electronic vs. Tobacco Cigarettes on Cardiovascular Health in Male and Female Mice
Authors: Lao Candice , Jordan Maria C. , Friedman Theodore C. , Tintut Yin , Shao Xuesi M. , Roos Kenneth 
Published: May 2024

Objective: Smoking electronic cigarettes (E-cig) has been promoted as a safer alternative to conventional tobacco cigarettes (CIG) and thus become popular, especially among younger generations. However, one mode of smoking nicotine containing products vs. another on the effects on health and gender are largely unknown. Hypothesis: Both E-cig and CIG have adverse effects on body weight as well as cardiovascular health. Methods: To closely mimic the Western population, we investigated the effects of two insults (diet and/or nicotine exposure) in mice. Nine-week old male and female Apoe−/− mice (C57BL/6 background) were placed on normal chow or high-fat diet (Western diet, WD) and/or exposed to air, E-cig, or CIG for 12 weeks. The E-cig and Cig exposures used a chronic-intermittent puff protocol for 10 hours a day, seven days a week during their active (dark) circadian cycle. Changes in body weight, cardiac structure, function, and atherosclerotic lesions were assessed and compared. Results: In males, body weight was significantly reduced by CIG exposure with both the normal diet or WD, while in females, only on WD. This suggests that CIG exposure had gender-dependent effects on the body weight. E-cig exposure, however, did not affect the body weight in both males and females on either diet compared with the controls. Echocardiographic analysis showed that left ventricular mass was increased while ejection fraction was reduced by both e-cigarette and CIG-exposure. These data suggest that both modes of nicotine delivery had gender-independent adverse effects on cardiac structure and function. En face analysis of the aorta in both genders showed that two insults (CIG and WD) are necessary to induce significantly greater lesions. There were no significant increases in lesions with E-Cigs. This suggests that CIG exposure had insult-dependent but gender-independent effects on atherosclerotic lesion development. Summary: These findings suggest that both electronic cigarettes and conventional tobacco cigarettes impose adverse effects on the body weight and cardiovascular health in modes of nicotine- and gender-dependent manners. Funding: Department of Defense CDMRP Grant PR 190942 (TCF) and DODCDMRP Grant PR190942-P1 (KPR). 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.
Podocytopathy and Nephrotic Syndrome in Smpdl3b Gene Knockout Mice
Authors: Li Guangbi , Huang Dandan , Ren Jenna , Zou Yao , Kidd Jason , Gehr Todd , Li Pin-Lan 
Published: May 2024

Recent clinical studies have shown that downregulation of sphingomyelin phosphodiesterase acid-like 3b (SMPDL3b) in podocytes is a hallmark of idiopathic nephrotic syndrome in children. Meanwhile, there is increasing evidence suggesting that changes of SMPDL3b level in podocytes determine the phenotypes of podocyte injury in glomerular diseases. However, it remains unknown whether SMPDL3b exclusively plays a crucial role in the pathogenesis of podocytopathy and nephrotic syndrome without any other pathogenic stimuli. In the present study, we tested whether Smpdl3b gene knockout induces podocyte injury and nephrotic syndrome in mice. By immunohistochemistry and confocal microscopy, we first confirmed that SMPDL3b was highly expressed in podocytes of wild type (WT) mice but undetectable in these cells of Smpdl3b knockout (KO) mice. Also, Western blot analysis showed that SMPDL3b was not detected in podocytes isolated from Smpdl3b KO mice compared to podocytes of WT mice. Although no significant morphologic changes in glomeruli were observed in Smpdl3b KO mice under light microscope, severe proteinuria and albuminuria were found in Smpdl3b KO mice compared to control littermates. Transmission electron microscopy showed that podocytes of Smpdl3b KO mice had distinctive foot process effacement and moderate microvillus formation and vacuolation. These functional and morphologic changes indicate the development of nephrotic syndrome in mice lacking Smpdl3b gene. In vitro, Smpdl3b gene silencing induced remarkable decrease in podocin levels in podocytes compared to control cells. Phalloidin staining of F-actin showed elevation of cortical actin and reduction of stress fiber in podocytes transfected with Smpdl3b shRNA. Such actin cytoskeleton rearrangement induced by Smpdl3b gene silencing was significantly attenuated by choline but exaggerated by CDP-choline, which are product and substrate of SMPDL3b, respectively. Furthermore, atom force microscopy was used to study mechanical properties of podocytes lacking Smpdl3b gene as the outcome of actin cytoskeleton reorganization. Smpdl3b gene deletion was found to increase podocyte height but decrease cortical elasticity in these cells. Moreover, these pathological changes were markedly inhibited by choline. Taken together, our findings suggest that SMPDL3b is essential for the maintenance of functional and structural integrity of podocytes and that Smpdl3b gene knockout may induce podocytopathy and nephrotic syndrome in mice. This study was supported by NIH grants DK054927 and DK120491. 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.
A Role for Septin GTPases in regulating cytoplasmic calcium handling in Drosophila cardiomyocytes
Authors: Tripoli Ben , Petersen Courtney , Smyth Jeremy 
Published: May 2024

Proper calcium handling in cardiomyocytes is paramount to maintaining cardiomyocyte contractility and heart function. Data from our lab and others have established that store operated calcium entry (SOCE) is an essential component of cardiomyocyte calcium regulation. SOCE refers to calcium influx that is activated by depletion of endo/sarcoplasmic reticulum (E/SR) calcium stores. The pathway is mediated by STIM proteins, which act as calcium sensors in the E/SR, and ORAI calcium selective influx channels in the plasma membrane. Both upregulation and suppression of SOCE in cardiomyocytes result in cardiomyopathy, demonstrating that proper regulation of cardiomyocyte SOCE is essential. However, the mechanisms responsible for SOCE regulation in cardiomyocytes are not well understood. To this end, septin GTPases have emerged as regulators of SOCE in non-cardiac tissues, with septin 1, 2, or 4 depletion resulting in SOCE suppression and septin 7 depletion resulting in SOCE upregulation. The role of septins in cardiomyocytes is nearly completely unknown. Through intravital imaging analysis of Drosophila heart contractility, we show that cardiomyocyte specific RNAi-based depletion of septins 1, 2, or 4 results in dilated cardiomyopathy nearly identical to that caused by SOCE suppression. Overexpression of SERCA, which pumps Ca2+ into SR stores, reversed the septin 2 phenotype, suggesting a mechanism whereby septin depletion reduces SR Ca2+ store refilling due to suppressed SOCE. In further support of SR Ca2+ store depletion, we found through jRGECO-based Ca2+ imaging of contracting hearts that contractile Ca2+ transients were significantly reduced in septin 2-depleted cardiomyocytes compared to controls. Interestingly, septin 7 suppression resulted in hypertrophic cardiomyopathy like that caused by SOCE upregulation, and micro-computerized tomography (microCT) analysis of heart size further confirmed the hypertrophic phenotype of septin 7 depleted hearts. This septin 7 phenotype was reversed by Orai depletion, supporting a role for SOCE dysregulation in the septin 7 phenotype. These results demonstrate for the first time an essential role for septins in cardiomyocyte physiology involving regulation of Ca2+ homeostasis and cycling. National institutes of Health. 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.
Diving into old age: exercise and aging affect cardiovascular control in a long-lived mammal, the Weddell seal
Authors: Rambo Ashley H , Mellish Jo-Ann E , Williams Cassondra , Horning Markus , Hindle Allyson G 
Published: May 2024

The central component of the mammalian dive response is bradycardia, which, in combination with other physiological mechanisms, conserves intrinsic oxygen stores and facilitates longer submersion. Several factors are hypothesized to affect diving heart rate ( fH) and its variability (HRV) through a shift in autonomic balance. This study aimed to elucidate how dive duration, aging, and exercise influence fH and HRV (calculated as root mean square of successive RR interval differences) of free-ranging Weddell seals ( Leptonychotes weddellii). We expected that mean dive fH and HRV would differ with dive duration, advancing age, and exercise intensity due to a shift in autonomic balance. We collected ECG data from free-ranging female Weddell seals in Erebus Bay, Antarctica (n=10 seals, n=120 dives, age range 9-25 years old). To increase the cost of transport, we affxed a “drag block” to three seals for a portion of their deployment period (n=30 dives). Linear mixed effects model selection identified the effects of dive behavior (duration and depth), seal age, and drag block presence on mean dive fH and HRV. As dive duration increased, mean dive fH decreased (F1,107=227.91, p<0.0001) while HRV increased (F1,103=84.47, p<0.0001), suggesting increased parasympathetic tone. HRV was reduced in older seals (F1,8=8.73, p=0.018), indicating attenuation of parasympathetic influence on bradycardia with advancing age. Consistent with this interpretation, HRV increased with dive duration more steeply in younger animals (age*duration: F1,103=10.31, p=0.002). When exercise effort was experimentally modified by attaching a drag block to free-ranging seals, both mean dive fH (F1,107=6.07, p=0.015) and HRV (F1,103=4.34, p=0.039) were affected; dive HRV was significantly higher when seals dove with a drag block. However, this result should be interpreted with caution until the effects of swimming effort on fH and HRV can be determined. There was a significant interaction between animal age and factors affecting cardiovascular control (age*drag: F1,107=5.16, p=0.028); mean dive fH increased with age when seals did not carry a drag block, but decreased with age when a drag block was present. Taken together, our results point to cardiovascular aging as a physiological element that could affect the foraging ability, fitness, and life history of a long-lived free-ranging mammal. Funding by the National Science Foundation (#0649609, #0440715, #2020706). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Mitochondrial Biogenesis and Remodeling Protein Response to Bouts of High-load vs High-volume Resistance Training
Authors: Mueller Breanna , Vann Chris , Roberts Michael , Kavazis Andreas 
Published: May 2024

Introduction: The effects of higher-load (HL; sets of 5 repetitions at 80% of 1-RM) versus higher-volume (HV; sets of 10 repetitions at 60% of 1-RM) resistance training (RT) on various molecular outcomes has proven to be similar between the two paradigms. However, the mitochondrial response to such training paradigms remains understudied. Therefore, the purpose of this study was to interrogate protein level responses of HL vs HV RT in proteins related to mitochondrial biogenesis and remodeling. We hypothesized that HV RT would have a greater effect on mitochondrial markers of biogenesis and remodeling than HL RT. Methods: Fifteen resistance trained males participated in 6 weeks of unilateral RT (single-leg leg press and single-leg leg extension) where each leg was randomly assigned to undergo either the HL or HV RT. Biopsies of the vastus lateralis were collected from both legs at PRE and POST and western blots analysis was used to assess mitochondrial proteins related to biogenesis and remodeling. The data collected were analyzed using two-way within-subject repeated measures ANOVAs. Results: Our results show no statistically significant effect of RT condition on markers of mitochondrial biogenesis and remodeling. However, there was a main effect of time in markers of both mitochondrial biogenesis and remodeling with MFN1 decreasing (p = 0.007, ƞ2 = 0.234) and PINK1 increasing (p = 0.009, ƞ2 = 0.222) from PRE to POST. Conclusion: HL and HV RT paradigms do not differentially affect the mitochondrial markers assessed, and our hypothesis that HV RT would elicit a greater response in markers of mitochondrial biogenesis and remodeling was not supported. However, our data supports the idea that mitochondrial adaptations can be stimulated regardless of the RT paradigm. This discovery could be advantageous for individuals selecting a mode of RT training that is most likely to result in the greatest exercise adherence as well as provide multiple health benefits. Furthermore, research into RT induced mitochondrial adaptations between sexes remains understudied, thus future investigations into these bioenergetic responses is warranted. Funding for assays and participant compensation was provided through discretionary laboratory funds from MR. Additionally, a portion of CG Vann’s effort was funded through the National Institutes of Health (R01AG054840). 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.
Liver-specific Bmal1 deletion in mice leads to increased aortic stiffness and altered vascular remodeling
Authors: Pati Paramita , Combs Robert , Srivastava Hemant , Colson Jackson , Millender-Swain Telisha , Bailey Shannon , Pollock Jennifer 
Published: May 2024

Circadian rhythms have an important role in cardiovascular physiology. Circadian clock genes are critical for vascular homeostasis. Global loss of the circadian clock gene Bmal1 increases aortic stiffness with impaired vascular function and blood pressure rhythm in mice. We previously found that hepatocyte-specific Bmal1 deletion (HBK) in the liver changes perivascular adipose tissue-mediated vascular function in young adult mice, indicating that liver circadian clock disruption distally affects function in another tissue and potential cross-talk between the liver and vasculature. We hypothesized that liver-specific Bmal1 deletion leads to aortic stiffness and pathological vascular remodeling. Studies were performed in 4- to 6- month old male HBK and flox control mice. Aortic stiffness, measured by pulse wave velocity, was significantly elevated in HBK mice compared to flox control mice (Flox: 1.84 ± 0.1 m/s; HBK: 2.9 ± 0.2 m/s; n = 5, p < 0.01). Systolic blood pressure (tail-cuff) in the light phase was similar in both flox control and HBK mice (Flox: 101 ± 1 mm Hg; HBK: 103 ± 2 mm Hg; n = 3-5, p = 0.35). Aortas and plasma were collected at ZT2 for histological analysis and metabolite measurements. MetaMorph software analysis of Masson’s Trichrome-stained aortic sections revealed significantly increased aortic wall fibrosis in HBK mice (% fibrosis per area, Flox 17.0% ± 3.3%, HBK 27.4% ± 2.1%, p=0.03). The medial cell number in H&E stained-aortic sections was increased in HBK mice compared to flox control mice (Flox: 534.6 ± 31.9; HBK: 1069 ± 90.1; p < 0.01). TUNEL stained apoptotic cells were also counted and more apoptotic cells were observed in young HBK mice aortas compared to flox controls (Flox: 224.4 ± 56.1; HBK: 408.4 ± 20.8; p = 0.02). Aortic wall thickness was not different in young adult HBK mice compared to flox control mice. Aortic levels of the lipid peroxidation marker vascular 4-hydroxynonenal (4-HNE), a measure of oxidative stress, were similar between flox control and HBK mice. In plasma, the oxidative stress marker, 8-hydroxy-2’-deoxyguanosine (8-OHdG), a DNA damage product, and plasminogen activator inhibitor-1 (PAI-1) were not different between genotypes. In conclusion, our findings indicate that liver circadian clock disruption increases aortic stiffness and fibrosis with higher cell numbers as well as aortic apoptosis. These data suggest that altered vascular remodeling in HBK mice may contribute to aortic stiffness resulting in cardiovascular disease. Funded by P01HL136267 to JSP, R21AA026906 to SMB, and AHA 856877 to PP. 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.